Literature DB >> 27755556

Muscadine Grape Skin Extract Induces an Unfolded Protein Response-Mediated Autophagy in Prostate Cancer Cells: A TMT-Based Quantitative Proteomic Analysis.

Liza J Burton1, Mariela Rivera2, Ohuod Hawsawi1, Jin Zou1, Tamaro Hudson3, Guangdi Wang4, Qiang Zhang4, Luis Cubano2, Nawal Boukli2, Valerie Odero-Marah1.   

Abstract

Muscadine grape skin extract (MSKE) is derived from muscadine grape (Vitis rotundifolia), a common red grape used to produce red wine. Endoplasmic reticulum (ER) stress activates the unfolded protein response (UPR) that serves as a survival mechanism to relieve ER stress and restore ER homeostasis. However, when persistent, ER stress can alter the cytoprotective functions of the UPR to promote autophagy and cell death. Although MSKE has been documented to induce apoptosis, it has not been linked to ER stress/UPR/autophagy. We hypothesized that MSKE may induce a severe ER stress response-mediated autophagy leading to apoptosis. As a model, we treated C4-2 prostate cancer cells with MSKE and performed a quantitative Tandem Mass Tag Isobaric Labeling proteomic analysis. ER stress response, autophagy and apoptosis were analyzed by western blot, acridine orange and TUNEL/Annexin V staining, respectively. Quantitative proteomics analysis indicated that ER stress response proteins, such as GRP78 were greatly elevated following treatment with MSKE. The up-regulation of pro-apoptotic markers PARP, caspase-12, cleaved caspase-3, -7, BAX and down-regulation of anti-apoptotic marker BCL2 was confirmed by Western blot analysis and apoptosis was visualized by increased TUNEL/Annexin V staining upon MSKE treatment. Moreover, increased acridine orange, and LC3B staining was detected in MSKE-treated cells, suggesting an ER stress/autophagy response. Finally, MSKE-mediated autophagy and apoptosis was antagonized by co-treatment with chloroquine, an autophagy inhibitor. Our results indicate that MSKE can elicit an UPR that can eventually lead to apoptosis in prostate cancer cells.

Entities:  

Mesh:

Substances:

Year:  2016        PMID: 27755556      PMCID: PMC5068743          DOI: 10.1371/journal.pone.0164115

Source DB:  PubMed          Journal:  PLoS One        ISSN: 1932-6203            Impact factor:   3.240


Introduction

Natural products with anticancer activities have gained increased attention due to their favorable safety and efficacy profiles as possible therapeutic agents that are not toxic to the surrounding healthy tissue. Of special interest is to determine how these novel compounds affect the endoplasmic reticulum (ER), an essential organelle for proper protein folding. Different physiological and pathological conditions can perturb protein folding in the ER, leading to a condition known as ER stress. ER stress activates the unfolded protein response (UPR), a complex intracellular signal transduction pathway that reestablishes ER homeostasis through adaptive mechanisms involving the stimulation of autophagy. The goal of the UPR is to restore optimal ER function. However, when persistent, ER stress can switch from the cytoprotective functions of UPR and autophagy to promote cell death mechanisms [1]. Flavonoids from naturally rich fruits modulate cell cycles, induce apoptosis, and inhibit extracellular regulated kinase (ERK) phosphorylation; mechanism that are linked to their confirmed anti-carcinogenic, anti-proliferative, co-chemotherapeutic, and estrogenic effects [2]. Numerous reports support the fact that many natural products play a positive role in cancer prevention and treatment by adjusting the oxidative stress response, inhibiting cancer cell proliferation and modulating apoptosis and autophagy; mechanisms that control cellular fate by regulating the turnover of organelles and proteins [3,4]. In general, autophagy blocks the induction of apoptosis, while apoptosis-associated caspase activation shuts off the autophagic process. In spite of its role as a self-digestion mechanism, autophagy is mainly activated to protect against cell death [5]. However, just like in the case of the UPR, stimulation of autophagy can be required to activate the cell death machinery under certain circumstances [6]. Anthocyanin compounds, the main bioactive components found in muscadine grape skin extract (MSKE) from the muscadine grape (Vitis rotundifolia), inhibit prostate cancer cell growth and promote apoptosis in vitro without toxicity to normal prostate epithelial cells [7]. Unlike other grape varieties, the phytochemical constituents of muscadine grapes have a higher concentration of anthocyanin 3,5-diglucosides, ellagic acid, and ellagic acid precursors [8]. In the case of purple skinned muscadine grapes, the anthocyanins are primarily delphinidin-3,5-diglucoside; cyanidin-3,5-diglucoside; and petunidin-3,5-diglucoside [8]. Anthocyanin 3,5 diglucosides are known to inhibit invasion in human hepatoma cells [9], and induce apoptosis and inhibit invasion in colorectal cancer cells [10]. MSKE has been shown to decrease tumor incidence, promote growth inhibition and stimulate cell death in various human cancer cell lines [7]. It can also revert the epithelial mesenchymal transition process [11]. Furthermore, the in vivo therapeutic effects of MSKE against prostate adenocarcinoma (PCa) are currently being investigated in a clinical trial [12]. In this study, proteomics, Western blot, acridine orange, Annexin V and TUNEL staining were used to determine global effects of MSKE on prostate cancer cells using C4-2 cells as a model. Our results revealed that MSKE regulated the expression of proteins important for ER stress response (GRP78, PDIA4, PDIA6, EIF2, EIF4 and Ire-1 alpha) and autophagy (ACIN1, PI4KA, PGK2 and MTDH). Pro-apoptotic markers were up-regulated, while anti-apoptotic protein BCL2 was down-regulated in the presence of MSKE; these effects were antagonized by co-treatment with chloroquine, suggesting that MSKE may promote ER stress-driven autophagic response leading to apoptosis.

Materials and Methods

Cell Culture, Reagents and Antibodies

C4-2 human prostate cells were grown in RPMI (Lonza, Alpharetta, GA) supplemented with 10% fetal bovine serum (Atlanta Biologicals, Flowery Branch, GA) and 1 × penicillin-streptomycin solution (Mediatech, Manassas, VA) at 37°C in a humidified incubator with 5% CO2. MSKE, which is composed mainly of anthocyanins, was prepared as previously described [7]. The protease inhibitor cocktail was purchased from Roche Molecular Biochemicals (Indianapolis, IN) and used according to the manufacturer’s instructions. Chloroquine (autophagy inhibitor) was purchased from Sigma Aldridge.(St. Louis, MO). Annexin V/cell death apoptosis kit was purchased from Thermo Fisher Scientific (Waltham, MA).

Gel-free Isobaric Labeling Tandem Mass Tag Quantitative Proteomic Profiling of C4-2 Cells Treated with MSKE

Cell lysis and protein extraction

Cells were plated on 150 cm2 culture plates at a cell density of 5 × 106 and treated the following day with 20 μg/ml MSKE for 72 h. Cells treated with 0.1% ethanol were used as controls. Proteins were extracted with RIPA buffer (1.5 M Tris pH 8.8, 1.75 g NaCl, 2 mL sodium dodecyl sulfate 10%, 2 mL Triton X-100; all reagents from Thermo Fisher Scientific, Waltham, MA). The cells were incubated on ice for 30 min, followed by 5 min sonication and centrifugation at 20,000 rpm for 5 min in preparation for protein extraction. Protein concentration was calculated on microtiter plates by measuring the absorbance at 595 nm of samples containing a commercial protein assay (Bio-Rad Laboratories, Hercules, CA) supplemented with 10 μL of phosphatase inhibitor cocktail and 10 μL of protease inhibitor cocktail (Roche Molecular Biochemicals, Indianapolis, IN).

Reduction, alkylation, and trypsin digestion

Aliquots with 100 mg of proteins from each sample were added to 100 ml of 200 mM triethyl ammonium bicarbonate TEAB (Sigma-Aldrich, St. Louis, MO). Reduction was performed by adding 5 ml of 200 mM tris (2-carboxyethyl) phosphine TCEP (Sigma-Aldrich, St. Louis, MO) to each replicate and incubating for 1 h at 55°C. Alkylation was carried out by adding 5 ml of 375 mM iodoacetamide (Bio-Rad Laboratories, Hercules, CA) to each sample and incubating for 30 min at room temperature. After alkylation, 1 ml of pre-chilled acetone was added and precipitation was allowed to proceed for 3 h at 20°C. Acetone-precipitated protein pellets were suspended in 100 ml of 200 mM TEAB and digested overnight at 37°C with 2.5 μg of sequencing grade modified trypsin (Promega Corp., Madison, WI) as previously described [13,14].

Isobaric Labeling with Tandem Mass Tag

Tandem mass tag TMT with varying molecular weights (126 ~ 131) (Thermo Scientifc, Waltham, MA) were applied as isobaric labels for the comparison of differential protein expression between C4-2 cells treated with ethanol (0.1%) and C4-2 treated with 20 μg/ml MSKE. Six digested samples were individually labeled with TMT6 reagents according to the manufacturer’s protocols. Three control (ethanol-treated) samples: TMT-126 (batch 1), TMT-127 (batch 2), and TMT-128 (batch3); and three MSKE-treated samples: TMT-129 (batch 1), TMT-130 (batch 2), and TMT-131 (batch3) were used in the studies. The labeled peptide mixtures were combined at equal ratios.

Fractionation of labeled peptide mixture by using a strong cation exchange column

The TMT-labeled peptide mixture was fractionated with a strong cation exchange SCX column (Thermo Fisher Scientific, Waltham, MA) on a Shimadzu 2010 high performance liquid chromatography (HPLC) equipped with an ultraviolet detector (Shimadzu, Columbia, MD) and a mobile phase consisting of buffer A (5 mM KH2PO4, 25% acetonitrile, pH 2.8) and buffer B (buffer A plus 350 mM KCl). The column was equilibrated with buffer A for 30 min before sample injection. A mobile phase gradient at a flow rate of 1.0 ml/min was set as follows: 1) 0 ~ 10 min: 0% buffer B; 2) 10 ~ 40 min: 0 ~ 25% buffer B; 3) 40 ~ 45 min: 25 ~ 100% buffer B; 4) 45 ~ 50 min: 100% buffer B; 5) 50 ~ 60 min: 100 ~ 0% buffer B; and 6) 60 ~ 90 min: 0% buffer B. Sixty fractions were initially collected, lyophilized, and combined into 10 final fractions based on SCX chromatogram peaks.

Desalination of fractionated samples

A C18 solid phase extraction SPE column (Thermo Fisher Scientific, Waltham, MA) was used to desalt all collected fractions as previously described [15]. Briefly, the 10 combined fractions were each adjusted to a final volume of 1 ml in a 0.25% trifluoroacetic acid TFA aqueous solution. The C18 SPE column was preconditioned with 1 ml acetonitrile and eluted in approximately 3 min before it was rinsed with 3 × 1 ml 0.25% TFA. The fractions were loaded on to the top of the SPE cartridge column slowly, and were reloaded once again to decrease lost peptide during column binding. Columns were washed with 4 × 1 ml 0.25% TFA aliquots before the peptides were eluted with 3 × 400 μl 80% acetonitrile/0.1% formic acid (aqueous). The eluted samples were lyophilized prior to the liquid chromatography mass spectrometry LC-MS/MS analysis.

LC-MS/MS analysis

Peptides were analyzed on an LTQ-Orbitrap XL (Thermo Fisher Scientific, Waltham, MA) instrument interfaced with an Ultimate 3000 Dionex LC system (Dionex, Sunnyvale, CA). High mass resolution was utilized for peptide identification and high-energy collision dissociation (HCD) was used for reporter ion quantification as previously described [15]. Briefly, the reverse phase LC system contained a peptide Cap-Trap cartridge (0.5 × 2 mm) (Michrom BioResources, Auburn, CA) and a pre-packed BioBasic C18 PicoFrit analytical column (75 μm i.d. × 15 cm length, New Objective, Woburn, MA) fitted with a FortisTip emitter tip. Samples were loaded onto the trap cartridge and washed with mobile phase A (98% H2O, 2% acetonitrile, and 0.1% formic acid) for concentration and desalting. Peptides were eluted over 180 min from the analytical column via the trap cartridge by using a linear gradient of 6 to 100% mobile phase B (20% H2O, 80% acetonitrile, and 0.1% formic acid) at a flow rate of 0.3 μl/min. The Orbitrap mass spectrometer was operated in a data-dependent mode in which each full MS scan (60,000 resolving power) was followed by six MS/MS scans where the three most abundant molecular ions were dynamically selected and fragmented by collision-induced dissociation with a normalized collision energy of 35% and subsequently scanned by HCD-MS2 with a collision energy of 45% as previously described [15]. Only the 2+, 3+, and 4+ ions were selected for fragmentation by collision-induced dissociation and HCD.

Database Search and TMT Quantification

The protein search algorithm SEQUEST was used to identify unique protein peptides using the Proteome Discoverer data processing software (version 1.2, Thermo Fisher Scientific, Waltham, MA). The ratios of TMT reporter ion abundances in MS/MS spectra generated by HCD from raw data sets were used For TMT quantification. Fold changes in proteins between control and treatment were calculated as previously described [15].

Western Blot

20–30 μg of proteins extracted with RIPA buffer were analyzed by SDS PAGE and transferred to a nitrocellulose membrane. Membranes were blocked with 5% non-fat dry milk in 1 × TBST buffer (BioRad, Hercules, CA) and incubated with primary antibodies overnight at 4°C. The following primary antibodies were used at a 1:1000 dilution LC3B, cleaved caspase-3, cleaved caspase-7, BAX, and BCL2 (Cell Signaling Technologies Danvers, MA.), anti-caspase-12, Ire-1α, GRP78, DFF45, and PARP (Abcam, Cambridge, MA). Anti-β-actin (1:500, Sigma-Aldrich, St. Louis, MO) were used as a loading control. Horseradish peroxidase (HRP)-conjugated secondary antibodies (Sigma Aldrich, St Louis, MO) were used and protein bands were visualized by a chemiluminescence method using the SuperSignal West Femto Maximum Sensitivity Substrate kit (Thermo Fisher Scientific, Waltham, MA). Images were analyzed with the ImageJ image processing program version 1.50b (National Institutes of Health, Bethesda, MD) to access the differential expression of key ER stress and apoptotic markers.

Analysis of Autophagy

Acridine Orange (AO) was used to analyze autophagy. Briefly, 5 × 103 cells were plated into Nunc 8-well chamber slides (Bio-Tek Instruments, Winooski, VT). Cells were serum-starved for 4 h and treated with increasing concentrations (0 μg/mL, 5 μg/mL, 10 μg/mL or 20 μg/mL) of MSKE for 72 h. Fixation was performed with methanol/ethanol (1:1 volume) for 5 min, followed by washes with 1 × PBS. Cells were exposed to 5 μg/ml AO for 15 min at 37°C, washed with 1 × PBS, and counterstained with 1 μg/ml DAPI (Santa Cruz Biotechnology, Santa Cruz, CA) before they were fixed with Fluorogel mounting medium (Electron Microscopy Sciences, Hatfield, PA). Co-treatments with the autophagy inhibitor (20 μM chloroquine) for 72 h was also performed. Fluorescence microscopy was performed at 40 × oil magnification on a Zeiss fluorescence microscope equipped with the AxioVision (release 4.8) imaging software and the ApoTome.2 optical sections system (Carl Zeiss Microscopy GmbH, Jenna, Germany).

Immunofluoresence for LC3B

5 × 103 cells were plated into Nunc 8-well chamber slides (Bio-Tek Instruments, Winooski, VT). Cells were serum-starved for 4 h and treated with 0 μg/mL or 20 μg/mL of MSKE with or without 20 μM chloroquine co-treatment for 72 h. Fixation was performed with methanol/ethanol (1:1 volume) for 5 min, followed by washes with 1 × PBS. Subsequently, slides were incubated with primary antibody (LC3B) at 1:50dilution in Dako antibody diluent solution for 1 h at room temp. Slides were washed with 1× TBS-T (Dako, Camarillo, CA), then incubated with secondary antibody in the dark for 1 h at room temp. Anti-rabbit Oregon green 488 was utilized as a secondary, and slides were then counterstained with 1 μg/ml DAPI (Santa Cruz Biotechnology, Santa Cruz, CA) before they were fixed with Fluorogel mounting medium (Electron Microscopy Sciences, Hatfield, PA). Fluorescence microscopy was performed at 40 × oil magnification on a Zeiss fluorescence microscope equipped with the AxioVision (release 4.8) imaging software and the ApoTome.2 optical sections system (Carl Zeiss Microscopy GmbH, Jenna, Germany).

TUNEL Assay

The terminal deoxynucleotidyl transferase (TdT) dUTP nick-end tabeling (TUNEL) assay was used to detect apoptosis. Briefly, 5 × 103 cells were plated into 16-well Nunc chamber slides (Bio-Tek, Winooski, VT). Cells were serum starved for 4 h and treated with increasing concentrations of MSKE (0 μg/mL, 5 μg/mL, 10 μg/mL or 20 μg/mL) for 72 h. The cells were fixed with 4% paraformaldehyde and permeabilized with 0.1% sodium citrate and 0.1% Triton X-100. DNA fragmentation was determined by TUNEL according to the manufacturer’s instructions (Roche Applied Science, Penzberg, Germany) prior to counterstaining with 1 μg/ml DAPI (Santa Cruz Biotechnology, Santa Cruz, CA). Slides were mounted with Fluorogel mounting medium (Electron Microscopy Sciences, Hatfield, PA) and visualized under 40 × oil magnification on a Zeiss fluorescence microscope equipped with the AxioVision (release 4.8) imaging software and the ApoTome.2 optical sections system (Carl Zeiss Microscopy GmbH, Jenna, Germany).

Annexin V/Cell Death Apoptosis Kit

Annexin V was also used to detect apoptosis. Briefly C4-2 Cells were serum starved for 4 h and treated with different concentrations of MSKE (0 μg/mL, 5 μg/mL) for 72 h, with or without 20 μM chloroquine. Apoptosis was assessed by Alexa Fluor 488 Annexin V and propidium iodide double staining and flow cytometry was performed using Accuri C6 Flow Cytometer (Accuri Cytometers Inc., Ann Arbor, MI.) according to the manufacterer instructions. Cells that stained positive for Annexin V- Alexa Fluor 488 and negative for PI (Alexa Fluor 488+/PI-) were considered to be undergoing early apoptosis; Alexa Fluor 488+/PI+ were considered as late apoptosis; Alexa Fluor 488-/PI- considered non-apoptotic (viable). Experiments were performed in triplicate in two independent experiments, and a representative result displayed in the form of early/late apoptosis graphs.

Statistical Analysis

Cytotoxicity assays and proteomics analyses were performed in triplicate, and similar results were obtained on at least three separate studies. Statistical analysis was performed using paired or unpaired t-tests, as appropriate, using the GraphPad PRISM v6.03 statistical software (GraphPad Software, La Jolla, CA). A p value of ≤ 0.05 was considered statistically significant and all data are presented as means ± standard error and range.

Results

Proteomic Profiling of C4-2 Cells Treated with MSKE with a Gel-Free Isobaric Labeling TMT Quantitative Proteomic Approach

The differential expression of proteins between untreated (0.1% ethanol) and treated (20 μg/ml MSKE) C4-2 cells was determined based on a gel-free isobaric labeling TMT quantitative proteomic approach for further validation and identification of novel proteins. Over 1,855 proteins were identified from control and treated C4-2 cell lysates. Among them, 465 significantly differentially expressed proteins contained TMT signals that were used to determine protein expression ratios between treated and control C4-2 cells. Proteins up-regulated or down-regulated at least 1.2 fold were organized according to biological processes (Fig 1). The detailed information including protein ID, gene name, number of amino acids, molecular weight, calculated pI, description, coverage samples, protein expression, change folds, and p-values are shown in S1 Table. Proteins that had a fold change of at least 1.2 and p-values ≤ 0.05 were closely examined and are listed in Table 1. MSKE-treated C4-2 cells expressed 254 up-regulated and 211 down-regulated proteins when compared to C4-2 control cells.
Fig 1

TMT labeled proteins identified by MS and organized according to biological processes.

Fig 1 shows proteins up-regulated or down-regulated at least 1.2 fold in C4-2 cells treated with 20 μg/ml MSKE as identified by the MASCOT database.

Table 1

Differentially expressed proteins in MSKE-treated and control cultures.

DescriptionScoreP-valueGene SymbolΣcoverageChange FoldMW [kDa]calc. pI
APOPTOSIS
Peptidyl-prolyl cis-trans isomerase F, mitochondrial85.792.63417E-09PPIF21.261.2322.039.38
Aldo-keto reductase family 1 member C120.020.009954054AKR1C15.451.8824.947.49
PAX3- and PAX7-binding protein 131.820.000657658PAXBP13.13-1.4357.405.25
*annexin A4220.768.39334E-23ANXA420.87-1.2036.066.13
Rho guanine nucleotide exchange factor (GEF) 1697.391.82266E-10ARHGEF1612.33-1.2917.106.13
BCL2-associated transcription factor 130.770.000837529BCLAF13.64-1.2352.8911.22
Cyclin-dependent kinase 531.840.000654636CDK55.48-1.2033.287.66
ARL-6-interacting protein 1647.581.7459E-65CG1032618.541.3217.157.96
*Cytochrome c oxidase subunit 4 isoform 1, mitochondrial57.861.63682E-06COX4I113.021.2819.569.51
*Cytochrome c oxidase subunit 7A2, mitochondrial107.111.94405E-11COX7A215.661.239.399.76
casein kinase 2, alpha 1 polypeptide103.294.68943E-11CSNK2A111.95-1.2045.287.94
*Catenin delta-1818.431.43523E-82CTNND119.21-1.2990.347.03
Drebrin-like protein45.332.93089E-05DBNL3.4-1.2043.015.03
Diablo homolog, mitochondrial29.520.001116863DIABLO37.661.468.845.01
Dynein light chain 2, cytoplasmic163.124.87128E-17DYNLL232.58-1.2310.347.37
elongation factor 1-delta isoform 4734.763.34299E-74EEF1D36.191.2928.544.92
Glutamate-cysteine ligase, modifier subunit, isoform CRA_a140.938.07457E-15GCLM18.51.3228.606.02
Growth/differentiation factor 15188.911.28552E-19GDF1514.291.3234.129.66
*Lactoylglutathione lyase795.532.79874E-80GLO155.62-1.2019.036.05
Golgi phosphoprotein 361.956.37832E-07GOLPH312.85-1.2432.916.71
High mobility group protein B1757.121.9406E-76HMGB139.53-1.2724.885.74
lamin-B1 isoform 255.312.94217E-06LMNB12.661.2443.005.12
mitogen-activated protein kinase 3106.762.10863E-11MAPK39.68-1.2217.928.70
Macrophage migration inhibitory factor316.042.48889E-32MIF55.65-1.2612.477.88
Cytochrome c oxidase subunit 240.848.24138E-05MT-CO24.411.4425.554.82
NEDD8-activating enzyme E1 regulatory subunit isoform c86.982.00638E-09NAE15.171.2750.595.27
occludin78.581.38788E-08OCLN10.5-1.6423.316.06
*Programmed cell death protein 6428.901.28687E-43PDCD69.631.3115.578.19
Prohibitin1313.074.9365E-132PHB64.341.2329.795.76
Peptidyl-prolyl cis-trans isomerase NIMA-interacting 128.560.001393157PIN19.2-1.6018.238.82
Protein kinase C delta type88.671.35752E-09PRKCD6.51-1.3577.457.75
Phosphoserine aminotransferase1228.551.397E-123PSAT148.671.2645.339.03
Tyrosine-protein phosphatase non-receptor type673.964.01791E-08PTPN63.43-1.2066.197.23
*Ras-related protein Rab-21116.332.32652E-12RAB214.891.2024.337.94
*Ras-related protein Rab-5A157.521.76979E-16RAB5A12.441.2722.168.82
*Ras-related protein Rab-5B220.129.73258E-23RAB5B17.211.2723.698.13
*Ras-related C3 botulinum toxin substrate 166.402.29241E-07RAC111.981.2221.448.50
Sigma non-opioid intracellular receptor 132.660.000542001SIGMAR16.42-1.2121.005.45
Guanine nucleotide exchange factor VAV225.090.00309803VAV21.91-1.2796.976.90
glycogen synthase kinase 3 beta37.060.000196789GSK3B20.19-1.2511.568.02
AUTOPHAGY
*apoptotic chromatin condensation inducer in the nucleus isoform 3124.923.21851E-13ACIN13.23-1.60147.306.73
*Protein LYRIC25.490.00282488MTDH3.041.9157.499.54
*Phosphoglycerate kinase 2651.027.91169E-66PGK220.14-1.2244.778.54
*Phosphatidylinositol 4-kinase alpha27.370.001832314PI4KA0.931.19231.176.87
Ubiquilin-429.370.001156112UBQLN45.491.4463.815.22
CELL PROLIFERATION
ADP-ribosylation factor-like protein 8A72.865.17257E-08ARL8A9.14-1.3721.407.77
BolA-like protein 2150.269.41588E-16BOLA223.03-1.2816.928.19
Calcium-binding protein 3962.815.24105E-07CAB396.16-2.4339.846.89
DEAD (Asp-Glu-Ala-Asp) box helicase 5197.541.76228E-20DDX518.82-1.2451.709.03
Deoxyribonucleoside 5'-monophosphate N-glycosidase160.149.68456E-17DNPH129.311.3019.105.05
Eukaryotic peptide chain release factor GTP-binding subunit ERF3A118.281.48531E-12GSPT16.011.2055.725.62
Nucleolar GTP-binding protein 133.060.000494311GTPBP42.12-1.2360.019.39
*HEAT SHOCK FACTOR PROTEIN 181.237.53356E-09HSF15.25-1.4631.925.38
Ragulator complex protein LAMTOR228.860.00130017LAMTOR214.41.6013.505.40
*minichromosome maintenance complex component 2146.212.39378E-15MCM26.81-1.5691.226.43
DNA replication licensing factor MCM3317.451.79731E-32MCM313.78-1.2585.596.15
DNA replication licensing factor MCM482.295.90347E-09MCM44.86-1.5592.666.98
minichromosome maintenance complex component 5184.103.8897E-19MCM58.68-1.5177.548.60
DNA replication licensing factor MCM695.872.58985E-10MCM636.14-1.639.534.41
MCM7 isoform 265.312.94243E-07MCM74.24-1.2860.606.25
N-myc downstream regulated 1559.731.06484E-56NDRG120.37-1.3735.276.34
Nucleolar and coiled-body phosphoprotein 1262.615.48094E-27NOLC111.441.2473.569.47
protein phosphatase, Mg2+/Mn2+ dependent, 1G333.884.09025E-34PPM1G7.75-1.2357.314.34
protein phosphatase 1 regulatory subunit 12A isoform b148.471.42272E-15PPP1R12A3.51.61105.585.38
protein phosphatase 1, regulatory subunit 885.592.76058E-09PPP1R810.24-1.4922.275.92
Serine/threonine-protein phosphatase 2A 55 kDa regulatory subunit B alpha isoform372.955.06492E-38PPP2R2A13.42-1.2451.666.20
Delta-3 of Serine/threonine-protein phosphatase 2A 56 kDa regulatory subunit delta41.007.94328E-05PPP2R5D2.421.5258.426.77
protein phosphatase 3, regulatory subunit B, alpha50.179.61612E-06PPP3R111.25-1.3518.204.92
protein kinase, AMP-activated, gamma 1 non-catalytic subunit61.427.2062E-07PRKAG17.69-1.2828.277.02
spindle pole body component 24 homolog (SPBC24), mRNA40.858.22243E-05SPC2411.26-1.2417.304.93
Testin32.010.000629506TES5.591.5920.646.48
*E3 ubiquitin-protein ligase UBR5120.379.17712E-13UBR51.51.21308.385.85
ZW10 protein55.912.56448E-06ZW102.981.3676.766.32
CYTOSKELETAL
Neuroblast differentiation-associated protein AHNAK254.323.7017E-26AHNAK10.05-1.24628.706.15
actin-related protein 2/3 complex subunit 4 isoform b27.120.001940886ARPC410.26-1.219.557.52
Actin-related protein 2/3 complex subunit 542.985.03501E-05ARPC59.631.3714.805.06
CCDC88A protein61.956.37733E-07CCDC88A0.331.21207.675.97
Calicin27.870.001633052CCIN2.38-3.1566.548.18
Cytoskeleton-associated protein 540.219.52796E-05CKAP54.931.3222.748.05
CLIP-associating protein 2105.223.00771E-11CLASP21.811.31138.788.34
claudin domain-containing protein 1 isoform b28.750.001333521CLDND15.071.4331.036.11
Protein cordon-bleu22.690.005382698COBL0.551.61136.608.07
*cortactin28.610.001377209CTTN9.811.6929.604.91
DmX-like protein 224.410.003622DMXL20.2-1.36339.436.38
DnaJ homolog subfamily B member 635.270.000297167DNAJB619.71.257.887.40
Niban-like protein 1147.681.7054E-15FAM129B5.73-1.2282.636.15
Filamin-B2200.568.788E-221FLNB20.64-1.22275.505.78
Huntingtin-interacting protein K59.271.18304E-06HYPK11.63-1.5714.664.93
Intraflagellar transport protein 27 homolog36.740.000211836IFT276.22.3114.024.64
Junction plakoglobin400.468.9848E-41JUP14.63-1.2481.696.14
Kinesin-like protein26.050.002483133KIF3C0.891.9175.757.15
Kinesin light chain 223.070.004931738KLC21.151.2557.148.21
Keratin, type II cytoskeletal 83479.340KRT862.32-1.2753.675.59
LIM domain and actin-binding protein 144.213.79315E-05LIMA13.091.4843.168.51
macrophage erythroblast attacher49.941.01391E-05MAEA19.63-1.2811.838.00
Microtubule-associated proteins 1A/1B light chain 3 beta 232.170.000606736MAP1LC3B211.21.6814.628.68
palmitoylated 5 (MAGUK p55 subfamily member 5)72.665.42001E-08MPP58.05-1.2617.186.70
Protein PRRC1161.427.21439E-17PRRC16.971.2246.675.83
Radixin176.112.44856E-18RDX7.891.3068.526.37
Ras-related protein R-Ras117.961.59848E-12RRAS12.84-1.2523.476.93
Na+/H+ exchange regulatory co-factor (NHERF) mRNA98.761.32928E-10SLC9A3R114.65-1.4229.426.80
spectrin, beta, non-erythrocytic 235.290.000295801SPTBN21.61-1.48105.607.75
tubulin, beta 6 class V1231.716.7485E-124TUBB655.67-1.2244.574.93
*Alpha-taxilin32.110.000615177TXLNA2.561.3761.856.52
ER STRESS
Cystathionine gamma-lyase306.482.24785E-31CTH13.31.4739.486.90
*Translation initiation factor eIF-2B subunit alpha33.770.000419759EIF2B14.611.5116.926.90
Protein Niban67.071.96515E-07FAM129A3.021.44103.074.78
Mesencephalic astrocyte-derived neurotrophic factor139.841.03761E-14MANF25.271.2920.698.69
B-cell receptor-associated protein 31389.581.10175E-39BCAP3122.361.2127.978.44
*Eukaryotic translation initiation factor 4E-binding protein 1124.813.30025E-13EIF4EBP115.251.2812.575.48
Endoplasmic reticulum resident protein 29364.953.20115E-37ERP2926.051.3028.987.31
Endoplasmin6243.820HSP90B152.931.3092.414.84
*78 kDa glucose-regulated protein7582.640HSPA560.241.6772.295.16
*60 kDa heat shock protein, mitochondrial19539.310HSPD182.021.2361.025.87
Protein disulfide-isomerase1239.551.1085E-124P4HB49.461.3832.138.51
Protein disulfide-isomerase3026.262.3635E-303P4HB58.071.3757.084.87
*Protein disulfide-isomerase A43139.650PDIA453.181.2172.895.07
*Protein disulfide-isomerase A61106.042.4891E-111PDIA631.351.2647.815.08
*Thioredoxin-related transmembrane protein 230.710.00084918TMX210.471.2229.628.65
E3 UFM1-protein ligase 142.965.05825E-05UFL13.931.2057.556.30
endoplasmic reticulum-resident ubiquitin-like domain member 1 protein (Fragment)59.251.1885E-06HERPUD18.191.3726.205.77
GENE EXPRESSION
acidic leucine-rich nuclear phosphoprotein 32 family member E isoform 3313.174.81956E-32ANP32E22.27-1.4325.113.74
Ataxin-2-like protein434.723.37392E-44ATXN2L1.141.54102.838.63
Barrier-to-autointegration factor382.785.27164E-39BANF140.45-1.3610.056.09
C5orf38 protein34.050.000393587C5orf388.151.3314.6811.27
chromobox homolog 1157.351.8397E-16CBX124.4-1.2219.315.02
CD81 molecule122.315.88048E-13CD8121.51-1.2410.094.59
Coiled-coil-helix-coiled-coil-helix domain-containing protein 2, mitochondrial45.542.79254E-05CHCHD211.261.5215.509.22
UMP-CMP kinase isoform a632.765.29998E-64CMPK125-1.2225.847.97
Cleavage and polyadenylation specificity factor subunit 748.601.37945E-05CPSF710.551.3226.139.51
Probable ATP-dependent RNA helicase DDX689.471.13097E-09DDX68.281.2454.388.66
Enhancer of mRNA-decapping protein 4349.201.20135E-35EDC411.86-1.25109.665.99
Elongation factor 1-beta352.915.11228E-36EEF1B244.891.2024.754.67
Zinc phosphodiesterase ELAC protein 237.700.000169824ELAC23.79-1.2056.067.43
EWS RNA-binding protein 1149.951.01187E-15EWSR19.42-1.3632.169.82
G-rich sequence factor 1 isoform 268.691.35317E-07GRSF16.92-1.3436.595.69
general transcription factor IIA, 1, 19/37kDa76.722.12814E-08GTF2A118.64-1.606.744.72
General transcription factor IIF subunit 259.041.24847E-06GTF2F25.22-1.2828.369.23
histone H2A.V isoform 2969.321.16911E-97H2AFV16.671.4412.1410.46
Heterogeneous nuclear ribonucleoprotein A/B289.201.20359E-29HNRNPAB17.861.2530.287.91
heterogeneous nuclear ribonucleoprotein D (AU-rich element RNA binding protein 1, 37kDa)555.962.53589E-56HNRNPD50.89-2.1812.638.57
insulin-like growth factor 2 mRNA binding protein 328.170.001524053IGF2BP312.35-1.208.895.78
La ribonucleoprotein domain family, member 758.031.57398E-06LARP77.19-1.4338.189.32
39S ribosomal protein L12, mitochondrial188.091.5512E-19MRPL1229.291.4721.338.87
myb-related protein A isoform 228.340.001465548MYBL11.451.3078.906.68
Myosin Ic575.173.03883E-58MYO1C15.53-1.2592.278.87
nuclear cap binding protein subunit 1, 80kDa34.350.000367282NCBP129.27-1.309.186.77
NELF-D of Negative elongation factor C/D34.110.00038815NELFCD1.72-1.8865.445.10
Cleavage and polyadenylation specificity factor subunit 563.274.70977E-07NUDT2127.31-1.3326.218.82
Phosphorylated adapter RNA export protein29.120.001224616PHAX2.79-1.2544.385.40
phosphatidylinositol-binding clathrin assembly protein isoform 4133.724.24178E-14PICALM8.53-1.2659.888.76
Pentatricopeptide repeat-containing protein 3, mitochondrial86.222.3862E-09PTCD37.691.2878.506.42
Putative peptidyl-tRNA hydrolase PTRHD133.650.000431519PTRHD117.86-1.2615.809.10
retinoblastoma binding protein 733.520.000444631RBBP77.69-1.3346.915.07
RNA-binding protein 10 isoform 553.584.38531E-06RBM103.921.51110.306.28
Splicing factor 4536.910.00020387RBM174.991.2044.935.97
ATP-dependent DNA helicase Q147.071.9619E-05RECQL2.47-1.4673.417.88
ribonuclease H2 subunit B isoform 230.810.000829851RNASEH2B8.17-1.3928.998.82
Ribonuclease P protein subunit p1468.051.56675E-07RPP1416.13-1.2913.687.75
Ribonuclease P protein subunit p3874.833.28852E-08RPP386.36-1.3231.819.92
splicing factor 3A subunit 1 isoform 2117.451.79925E-12SF3A17.011.2181.635.34
Nuclear receptor coactivator NC0A-6231.320.000737904SNW12.671.2043.319.70
Splicing regulatory glutamine/lysine-rich protein 156.272.36048E-06SREK11.971.2159.3510.39
Serine/arginine repetitive matrix protein 178.241.49833E-08SRRM18.19-1.24102.2711.84
Splicing factor arginine/serine-rich 1125.870.002588213SRSF116.251.3413.136.28
Splicing factor, arginine/serine-rich 5120.948.056E-13SRSF525.81-1.3714.4310.08
Transcription elongation factor A protein 191.047.86502E-10TCEA117.281.2933.958.38
EKC/KEOPS complex subunit TPRKB78.141.53358E-08TPRKB12.68-1.3116.086.30
tRNA (guanine-N(1)-)-methyltransferase46.822.0797E-05TRMT52.951.3358.218.62
Exportin-528.180.001521507XPO512.21-1.20136.225.80
zinc finger, CCHC domain containing 872.695.3827E-08ZCCHC812.28-1.5218.104.65
zinc finger protein 2 (Fragment)27.620.001729816ZNF20.831.43118.556.43
Zinc finger protein 51159.641.08643E-06ZNF5115.56-1.5128.257.66
*Zinc finger SWIM domain-containing protein 515.310.029444216ZSWIM50.59-2.63130.557.18
dolichyl-diphosphooligosaccharide—protein glycosyltransferase subunit 2 isoform 2 precursor35.790.000263633RPN215.771.2267.686.06
IMMUNE RESPONSE
Beta-defensin 11925.850.002601985DEFB1197.14-1.929.818.57
F-box/LRR-repeat protein 827.080.001958845FBXL86.21.5314.206.99
Guanine nucleotide-binding protein-like 174.733.36284E-08GNL14.21.8028.694.69
HLA class II histocompatibility antigen, DQB1*0602 beta chain25.920.002558586HLA-DQB15.881.3115.768.85
Interferon regulatory factor 7203.304.67539E-21IRF74.531.4842.255.34
Dual specificity mitogen-activated protein kinase kinase 338.590.000138357MAP2K35.661.3336.156.25
Macrophage-expressed gene 1 protein49.941.01391E-05MPEG10.841.4978.547.65
*G antigen family B member 1116.722.13016E-12PAGE119.86-1.5316.144.22
*Phosphoinositide 3-kinase regulatory subunit 424.480.003564511PIK3R40.441.46153.017.17
Pirin158.711.3466E-16PIR7.241.3132.096.92
Parathymosin230.828.27378E-24PTMS22.551.4411.524.16
SAM domain and HD domain-containing protein 160.219.52153E-07SAMHD16.15-1.4969.407.20
single immunoglobulin and toll-interleukin 1 receptor (TIR) domain81.027.90679E-09SIGIRR11.97-1.3315.504.86
Serine/threonine-protein kinase TBK160.838.26038E-07TBK12.74-1.3983.596.79
Zinc finger CCCH-type antiviral protein 186.042.48886E-09ZC3HAV13.58-1.2077.858.38
METABOLISM
Kynurenine/alpha-aminoadipate aminotransferase, mitochondrial112.096.18431E-12AADAT12.121.2447.797.21
Abhydrolase domain-containing protein 10, mitochondrial35.490.000282488ABHD1013.731.2333.918.57
acyl-CoA thioesterase 949.121.22462E-05ACOT99.56-1.3115.458.59
Adenylate kinase isoenzyme 1250.339.27582E-26AK127.84-1.2021.628.63
GTP:AMP phosphotransferase, mitochondrial isoform c91.187.61682E-10AK322.931.2918.188.78
Argininosuccinate synthase548.151.52978E-55ASS126.22-1.3550.798.40
ATP synthase subunit beta, mitochondrial6847.360ATP5B72.781.2056.525.40
ATP synthase gamma chain89.041.24654E-09ATP5C18.81.3227.507.42
ATP synthase subunit epsilon-like protein, mitochondrial32.850.0005188ATP5EP213.731.315.8010.14
ATP synthase subunit b, mitochondrial198.921.28165E-20ATP5F111.721.3628.899.36
ATP synthase, H+ transporting, mitochondrial F0 complex, subunit C1 (Subunit 9)247.941.60823E-25ATP5G17.072.3510.1910.40
ATP synthase-coupling factor 6, mitochondrial78.671.35831E-08ATP5J17.591.2412.589.52
ATP synthase subunit f, mitochondrial isoform 2d42.395.76766E-05ATP5J259.181.595.749.70
ATP synthase subunit g, mitochondrial88.081.55639E-09ATP5L28.951.208.4510.29
ATP synthase subunit O, mitochondrial607.691.70258E-61ATP5O38.971.2223.269.96
ATP synthase mitochondrial F1 complexassembly factor 2, mitochondrial42.395.76766E-05ATPAF221.19-1.2413.059.51
ADP-ribosyl cyclase 249.301.17453E-05BST11.891.2135.707.80
citrate lyase beta like (CLYBL), transcript variant 2, mRNA25.670.002710192CLYBL1.991.4332.838.29
Coatomer subunit gamma-2296.912.03587E-30COPG27.23-1.2197.565.81
Cubilin26.560.002208005CUBN0.281.26398.485.35
Lanosterol 14-alpha demethylase31.320.000737904CYP51A16.311.2025.639.22
Elongation factor 1-alpha 12876.542.2169E-288EEF1A117.321.4250.128.95
Elongation factor 1-gamma847.831.6494E-85EEF1G39.131.2450.096.67
Eukaryotic translation initiation factor 3 subunit H219.981.0051E-22EIF3H12.781.2939.916.54
Eukaryotic translation initiation factor 3 subunit K146.262.36701E-15EIF3K20.181.3025.044.93
eukaryotic translation initiation factor 4A2236.482.24941E-24EIF4A240.61-1.7041.265.64
Eukaryotic translation initiation factor 5355.382.89998E-36EIF520.881.2749.195.58
Mitochondrial enolase superfamily member 131.060.00078343ENOSF14.29-1.2149.756.48
Squalene synthase308.021.57875E-31FDFT119.271.2847.256.54
Fibronectin84.303.71838E-09FN11.38-1.75222.845.68
fibronectin 1 (FN1), transcript variant 5, mRNA84.303.71838E-09FN12.96-1.32111.236.21
Galactokinase65.272.97119E-07GALK110.711.6142.256.46
N-acetylgalactosamine kinase33.040.000496592GALK24.151.3947.606.19
FAD-linked sulfhydryl oxidase ALR73.983.99945E-08GFER12.21.2723.437.62
Glutathione S-transferase109.041.24616E-11GSTA312.21-1.2219.739.16
Glutathione S-transferase Mu 31530.928.0923E-154GSTM356.44-1.2426.545.54
Hydroxyacylglutathione hydrolase, mitochondrial32.510.000561048HAGH8.08-1.2628.847.33
Histone acetyltransferase type B catalytic subunit134.873.25617E-14HAT15.39-1.4039.765.92
Isopentenyl-diphosphate Delta-isomerase 175.332.93089E-08IDI115.861.2426.306.34
inositol-tetrakisphosphate 1-kinase28.460.001425608ITPK112.5-1.5819.456.39
L-lactate dehydrogenase A-like 6A362.006.31588E-37LDHAL6A7.23-1.2836.486.99
Phospholysine phosphohistidine inorganic pyrophosphate phosphatase113.454.51551E-12LHPP7.78-1.2329.156.15
lanosterol synthase isoform 354.263.7465E-06LSS3.071.4974.176.46
Leukotriene A-4 hydrolase45.872.58821E-05LTA4H2.361.4657.266.06
LYR motif-containing protein 756.052.48146E-06LYRM715.381.6811.959.66
NADP-dependent malic enzyme1228.391.4492E-123ME120.981.4064.116.13
NAD-dependent malic enzyme, mitochondrial isoform 2 precursor53.874.10204E-06ME25.011.5253.558.54
Cob(I)yrinic acid a,c-diamide adenosyltransferase, mitochondrial155.892.57529E-16MMAB28.41.3127.378.60
Mannose-6-phosphate isomerase289.431.1405E-29MPI18.68-1.2846.635.95
39S ribosomal protein L53, mitochondrial45.672.70836E-05MRPL5313.391.6512.108.76
Arylamine N-acetyltransferase 168.561.39222E-07NAT15.86-1.2833.886.54
NADH-ubiquinone oxidoreductase 75 kDa subunit, mitochondrial35.890.000257632NDUFS13.271.6166.885.38
NADH dehydrogenase [ubiquinone] iron-sulfur protein 3, mitochondrial34.690.000339625NDUFS319.231.778.608.03
nitric oxide synthase interacting protein (NOSIP), mRNA26.130.002437811NOSIP6.63-1.8117.938.00
nucleoporin 133kDa169.201.2026E-17NUP1337.19-1.26120.305.15
Nuclear pore complex protein Nup20541.856.53131E-05NUP2052.83-1.40227.786.19
Nuclear pore complex protein Nup9325.650.002722701NUP931.15-1.2579.836.18
nucleoporin 98kDa447.741.68228E-45NUP986.9-1.5326.867.39
propionyl-CoA carboxylase alpha chain, mitochondrial isoform c precursor24.300.003715352PCCA1.031.4674.957.36
phosphoacetylglucosamine mutase isoform 3113.804.17131E-12PGM38.031.3351.055.88
Arfaptin-231.820.000657658POR16.991.2047.377.81
Lipid phosphate phosphohydrolase 129.390.0011508PPAP2A7.041.2232.147.97
Palmitoyl-protein thioesterase 1126.472.25388E-13PPT19.48-1.3434.176.52
glucosidase 2 subunit beta isoform 2450.798.33915E-46PRKCSH20.191.2859.144.42
Prosaposin1508.141.5356E-151PSAP21.76-1.3358.075.17
Ran GTPase activating protein 1115.422.87351E-12RANGAP19.02-1.3557.744.53
rap1 GTPase-GDP dissociation stimulator 1 isoform 690.069.85348E-10RAP1GDS111.82-1.2056.505.44
60S acidic ribosomal protein P21310.748.4427E-132RPLP270.43-1.2911.664.54
SUMO-activating enzyme subunit 1481.736.71984E-49SAE118.79-1.2538.435.30
Sec1 family domain-containing protein 172.625.47514E-08SCFD16.131.2451.516.96
Succinate dehydrogenase [ubiquinone] flavoprotein subunit, mitochondrial344.953.19778E-35SDHA9.611.2663.537.24
Protein transport protein Sec24B38.990.000126098SEC24B0.89-1.48133.547.39
serine hydroxymethyltransferase, mitochondrial isoform 31864.723.3762E-187SHMT249.281.2453.428.15
Monocarboxylate transporter 1106.482.24967E-11SLC16A110.42-1.2951.808.50
Tricarboxylate transport protein, mitochondrial73.344.63657E-08SLC25A17.41.2033.999.89
Calcium-binding mitochondrial carrier protein Aralar264.843.27874E-07SLC25A138.111.2162.219.01
solute carrier organic anion transporter family member 1C1 isoform 330.950.000803526SLCO1C10.91.5273.228.85
Translocon-associated protein subunit alpha271.197.59987E-28SSR18.881.2529.364.61
Translocon-associated protein subunit delta141.517.06092E-15SSR417.51.4013.067.50
UDP-N-acetylhexosamine pyrophosphorylase80.698.52774E-09UAP12.971.2356.996.38
UTP—glucose-1-phosphate uridylyltransferase25.070.003111716UGP24.021.2355.647.88
Cytochrome b-c1 complex subunit 957.971.5948E-06UQCR1038.11.317.309.47
Cytochrome b-c1 complex subunit 794.763.34256E-10UQCRB21.621.2213.528.78
OXIDATIVE STRESS
Cytoplasmic aconitate hydratase179.531.11364E-18ACO16.97-1.3698.346.68
*Retinal dehydrogenase 1385.173.03767E-39ALDH1A117.951.3242.575.80
*Fatty aldehyde dehydrogenase262.186.06001E-27ALDH3A212.991.2354.817.88
Alkylated repair protein alkB78.291.48152E-08ALKBH55.48-1.4143.029.16
aspartyl/asparaginyl beta-hydroxylase isoform f131.037.88327E-14ASPH4.392.2383.224.92
Cytochrome b56186.522.22693E-09CYB5614.381.4527.548.56
Cytochrome b5126.092.45962E-13CYB5A42.86-1.2211.265.14
*Dehydrogenase/reductase SDR family member 167.711.69434E-07DHRS16.071.3133.897.83
Glycine N-methyltransferase39.200.000120226GNMT2.71-1.2532.727.02
MOSC domain-containing protein 1, mitochondrial40.119.7499E-05MARC113.89-1.2328.427.31
3-mercaptopyruvate sulfurtransferase72.725.34203E-08MPST14.481.2333.166.60
Bifunctional methylenetetrahydrofolate dehydrogenase/cyclohydrolase, mitochondrial33.260.000472063MTHFD25.412.0023.859.76
Myb-binding protein 1A64.543.5156E-07MYBBP1A0.83-1.29148.769.28
NADH dehydrogenase [ubiquinone] iron-sulfur protein 8, mitochondrial40.439.05733E-05NDUFS88.181.8612.409.98
*NAD(P)H dehydrogenase, quinone 1 (NQO1), transcript variant 3, mRNA513.204.78822E-52NQO152.481.2822.788.50
Prolyl 4-hydroxylase subunit alpha-236.080.000246604P4HA22.251.4160.595.71
Protoporphyrinogen oxidase87.401.8197E-09PPOX6.981.2646.817.31
Pyrroline-5-carboxylate reductase 293.934.04761E-10PYCR29.381.2333.627.77
Retinol dehydrogenase 1464.683.40408E-07RDH147.141.4436.848.79
*Sideroflexin-1318.981.26412E-32SFXN132.611.2135.609.07
*STEAP family member 2, metalloreductase90.069.86169E-10STEAP26.7-1.4745.958.91
PROTEOLYTIC
ADAM metallopeptidase domain 926.770.002103778ADAM93.82-1.3469.286.65
asparagine synthetase [glutamine-hydrolyzing] isoform b2335.193.0244E-234ASNS38.891.3162.137.06
Cyclin-dependent kinase 129.040.001247384CDK18.33-1.5727.497.06
*Collagen type IV alpha-3-binding protein48.531.40281E-05COL4A3BP1.67-1.4067.965.47
Cystatin-B190.508.90894E-20CSTB24.49-1.8211.137.56
Farnesyl pyrophosphate synthetase like-4 protein (Fragment)70.778.36775E-08FDPS8.62-3.1039.634.98
PSMA' of Glutamate carboxypeptidase 2414.933.21326E-42FOLH19.24-1.4677.956.67
Glucosamine—fructose-6-phosphate aminotransferase [isomerizing] 2148.171.52319E-15GFPT26.6-1.8776.887.37
Minor histocompatibility antigen H1360.588.74071E-07HM136.571.2136.796.68
*Hypoxia up-regulated protein 12096.902.0428E-210HYOU128.531.21111.275.22
Leucyl-cystinyl aminopeptidase91.926.43211E-10LNPEP2.78-1.26114.995.78
Mucosa-associated lymphoid tissue lymphoma translocation protein 129.410.001145513MALT11.97-1.4791.025.91
E3 ubiquitin-protein ligase MARCH527.450.001798871MARCH53.61.6931.218.70
Neprilysin670.638.64906E-68MME20-1.3385.465.73
neural precursor cell expressed, developmentally down-regulated 8101.646.8544E-11NEDD840-1.345.866.70
aminopeptidase NPEPL1 isoform 3158.361.45823E-16NPEPL14.84-1.2250.506.52
Ubiquitin thioesterase OTUB2229.611.09388E-23OTUB27.022.1112.939.29
*OTU domain-containing protein 6B102.585.52077E-11OTUD6B14.58-1.3721.795.10
Proteasome subunit beta type-6117.001.9941E-12PSMB625.11.2025.344.92
E3 ubiquitin/ISG15 ligase TRIM25166.222.38646E-17TRIM257.14-1.2270.938.09
Transcription intermediary factor 1-beta62.595.50752E-07TRIM2833.05-1.2388.495.77
*Ubiquitin-conjugating enzyme E2 variant 2369.351.16185E-37UBE2V260.611.5611.275.52
E3 ubiquitin-protein ligase UBR239.230.000119399UBR24-1.2766.017.42
Deubiquitinating protein VCIP13530.730.000845279VCPIP10.57-1.73134.247.20
X-prolyl aminopeptidase (Aminopeptidase P) 1, soluble38.350.000146218XPNPEP13.261.4162.105.73
OTHER
Armadillo repeat containing 236.310.000233884ARMC29.412.129.416.92
UPF0556 protein C19orf1033.480.000448745C19orf1013.871.2718.786.68
CDGSH iron-sulfur domain-containing protein 3, mitochondrial34.930.000321366CISD310.241.2414.2110.55
Protein FAM136A28.080.001555966FAM136A6.521.3015.637.61
hematological and neurological expressed 160.688.55067E-07HN19.35-1.3411.628.47
kelch-like protein 3527.780.001667247KLHL351.2-1.3562.857.83
Leucine-rich repeat-containing protein 4755.502.81838E-06LRRC472.571.4363.438.28
Nucleoside diphosphate-linked moiety X motif 221000.359.2264E-101NUDT222.121.5130.5711.56
Regulator of G-protein signaling 1036.150.000242661RGS1010.18-1.3119.605.87
Selenoprotein M28.070.001559553SELM9.66-1.3416.175.54
Serine/threonine-protein phosphatase 4 regulatory subunit 3A76.442.27171E-08SMEK13.15-1.2161.984.81
Protein kish-A37.020.000198609TMEM167A12.51.288.058.95
Transmembrane protein 20534.490.000355631TMEM2058.99-1.3721.188.62
Transmembrane protein 23842.685.39511E-05TMEM23810.231.4018.0311.53
Transmembrane protein 87A55.862.59243E-06TMEM87A9.11-1.3356.745.69
182 kDa tankyrase-1-binding protein106.182.40763E-11TNKS1BP12.6-1.46181.694.86
UDP-N-acetylhexosamine pyrophosphorylase-like protein 131.600.000691831UAP1L11.38-1.2456.996.32
zinc finger CCCH-type containing 1865.782.64005E-07ZC3H185.42-1.8739.044.89
Leucine-rich repeat-containing protein 59503.474.49936E-51LRRC5920.521.2234.919.57
rRNA 2'-O-methyltransferase fibrillarin180.129.71673E-19FBL11.53-1.3333.7610.18
Clustered mitochondria protein homolog54.603.46545E-06CLUH2.141.20146.586.13
ATP-dependent RNA helicase DDX31282.985.03956E-29DDX310.971.2480.899.83
Neurobeachin-like protein 223.890.004083194NBEAL20.431.66282.686.54
NHP2 ribonucleoprotein351.047.86182E-36NHP233.33-1.2215.019.25
WD repeat protein 5559.961.00925E-06WDR5521.74-1.4312.546.74
Nucleobindin-2526.892.04772E-53NUCB227.861.2450.165.12
1-phosphatidylinositol-4,5-bisphosphate phosphodiesterase eta-149.481.12644E-05PLCH10.81.38114.437.64
Ankyrin repeat domain-containing protein 584.773.3358E-09ANKEF11.421.3386.618.28
Calmodulin383.674.29621E-39CALM38.26-1.4016.834.22
Calcyclin-binding protein64.993.17122E-07CACYBP13.161.3026.198.25
calcium/calmodulin-dependent protein kinase kinase 2, beta41.307.42096E-05CAMKK26.41-1.4838.596.30
Calmodulin-regulated spectrin-associated protein 325.230.002999163CAMSAP30.481.56134.678.35
Calnexin1219.691.0747E-122CANX23.141.2167.534.60
Calcium-regulated heat stable protein 1181.646.85365E-19CARHSP110.88-1.4615.888.21
S-adenosylmethionine synthase isoform type-222.480.00564937MAT2A3.981.6219.469.10
40S ribosomal protein S28416.482.24773E-42RPS2830.431.657.8410.70
*Tetraspanin48.281.48594E-05TSPAN136.29-2.1117.756.29
Desmoglein-2112.815.23745E-12DSG27.61.23122.225.24
Integrin alpha-1026.550.002213095ITGA100.781.26112.476.68
Liprin-alpha-136.200.000239776PPFIA11.6-1.26133.896.25
WD repeat-containing protein 6146.622.17624E-05WDR616.56-1.2033.565.47
Syntaxin-1284.273.74231E-09STX126.881.6331.625.59
*Dihydropyrimidinase-related protein 531.720.00067262DPYSL53.681.6720.856.42
PDZ domain-containing protein GIPC1 isoform 233.420.000454988GIPC17.2-1.3026.065.57
Crk-II of Adapter molecule crk168.481.41897E-17CRK7.571.2633.815.55
Transducin-like enhancer protein 330.900.000812831TLE32.11-1.4582.177.20
Platelet-activating factor acetylhydrolase IB subunit gamma113.694.27563E-12PAFAH1B321.651.3425.726.84
Histone H3.3828.781.32475E-83H3F3A44.851.2915.3211.27
Histone H1.5536.772.10286E-54HIST1H1B21.242.4922.5710.92
Histone H1.21007.801.6588E-101HIST1H1C30.992.2921.3510.93
Histone H1.41069.831.0408E-107HIST1H1E30.592.8921.8511.03
Histone H2B type 1-C/E/F/G/I1342.186.0583E-135HIST1H2BC62.71.8413.9010.32
Histone H3.11117.981.5924E-112HIST1H3A44.851.5415.3911.12
Histone H41317.991.5896E-132HIST1H4A52.431.8511.3611.36
Histone H2A type 2-C969.321.16911E-97HIST2H2AC55.041.9713.9810.90
Histone H2B type 2-E1489.581.1021E-149HIST2H2BE62.71.8613.9110.32
Histone H3.21363.474.4975E-137HIST2H3A44.851.8215.3811.27
Histone H2A.x516.442.27136E-52H2AFX59.441.2215.1410.74
replication factor C subunit 5 isoform 434.070.000391742RFC52.672.2438.147.80
small ubiquitin-related modifier 2 isoform b precursor154.563.50042E-16SUMO216.9-1.398.115.41
deoxyuridine 5'-triphosphate nucleotidohydrolase, mitochondrial isoform 3160.149.68456E-17DUT21.991.2015.396.57
Single-stranded DNA-binding protein, mitochondrial882.965.06197E-89SSBP153.381.2217.259.60
WD repeat-containing protein 7221.020.007906786WDR720.541.73123.356.67
Alpha-2-HS-glycoprotein51.237.53356E-06AHSG4.92.1927.346.52
Stonin-237.610.00017338STON20.991.21101.105.39
protein arginine methyltransferase 1278.121.54264E-28PRMT134.46-1.3737.686.15
Proline-, glutamic acid- and leucine-rich protein 129.980.001004616PELP12.022.20110.024.30
TBC1 domain family member 10B32.110.000615177TBC1D10B0.87-2.1087.149.19
Nuclear ubiquitous casein and cyclin-dependent kinases substrate204.853.27022E-21NUCKS111.52-1.2327.285.08
SLD5 homolog (SLD5), mRNA72.765.29663E-08GINS412.842.1312.055.74
Microsomal triglyceride transfer protein large subunit39.580.000110154MTTP1.231.9899.298.41
Protein FAM87A23.600.004365158FAM87A4.9-1.4331.7210.01
39S ribosomal protein L2, mitochondrial47.971.5948E-05MRPL22.621.2233.2811.30
39S ribosomal protein L21, mitochondrial isoform a51.247.51623E-06MRPL2115.83-1.2013.7410.07
Serpin B6108.581.38613E-11SERPINB611.49-1.2146.345.76
Vomeronasal type-1 receptor 523.950.00402717VN1R51.96-1.5940.759.20
cilia and flagella associated protein 5844.443.59536E-05CFAP586.521.9911.039.23
Membrane-associated progesterone receptor component 1156.792.09251E-16PGRMC122.051.2921.664.70
FK506 binding protein12205.153.05816E-21FKBP1A35.14-1.373.965.78
Peptidyl-prolyl cis-trans isomerase B548.341.4649E-55PPIB46.31.2423.739.41
selenide, water dikinase 1 isoform 3221.267.4799E-23SEPHS116.21.2435.465.21
Probable Xaa-Pro aminopeptidase 391.646.86257E-10XPNPEP310.981.4548.085.62
mitochondrial ribosomal protein L38 (MRPL38)34.000.000398107MRPL383.571.2222.966.14
39S ribosomal protein L4, mitochondrial52.086.19534E-06MRPL415.21-1.2029.4810.13
MRPL43 protein (Fragment)88.641.36673E-09MRPL438.971.2315.958.66
60S ribosomal protein L3268.101.54882E-07RPL3212.781.2315.6111.44
proteasome assembly chaperone 4 isoform c50.678.57038E-06PSMG424.04-1.2311.216.51
N-terminal Xaa-Pro-Lys N-methyltransferase 1149.451.13471E-15NTMT111.61-1.9925.465.52
STE20/SPS1-related proline-alanine-rich protein kinase800.518.88891E-81STK3913.35-1.2459.606.29
toll interacting protein62.645.44503E-07TOLLIP17.5-1.278.658.35
SUMO-conjugating enzyme UBC9186.062.47947E-19UBE2I34.18-1.2718.008.66
Putative NOL1/NOP2/Sun domain family member 5B53.314.66317E-06NSUN5P17.14-1.7016.479.26
THO complex subunit 240.488.95365E-05THOC21.061.2397.216.51
ATP-dependent RNA helicase DHX2965.432.86418E-07DHX290.731.28155.148.09
Neuron-specific calcium-binding protein hippocalcin79.071.23796E-08HPCA6.221.6322.414.97
Olfactory receptor 5AC237.520.000177011OR5AC22.27-1.3935.288.94
A-kinase anchor protein 861.796.61769E-07AKAP82.891.6076.065.15
Myeloid-associated differentiation marker61.527.04693E-07MYADM15.651.7415.928.65
*NF-kappa-B-activating protein26.490.002243882NKAP1.451.6547.1110.11
*ATP-binding cassette sub-family A member 530.050.000988553ABCA50.86-5.84104.307.12
AP-1 complex subunit mu-247.211.90108E-05AP1M24.02-1.5348.088.22
AP-2 complex subunit mu-144.573.49424E-05AP2M18.27-1.2042.679.39
ADP-ribosylation factor 5967.371.83259E-97ARF556.111.2320.526.79
ADP-ribosylation factor guanine nucleotide-exchange factor 1 (brefeldin A-inhibited)440.409.12033E-45ARFGEF13.27-1.23142.446.13
ARFAPTIN 1175.922.55929E-18ARFIP117.141.2528.407.72
Cellular nucleic acid-binding protein117.581.74464E-12CNBP8.82-1.6218.737.71
Metal transporter CNNM322.850.005188CNNM30.911.2270.597.12
Protein CWC15 homolog66.102.45471E-07CWC154.8-1.3026.615.71
Acyl-CoA-binding protein504.053.93581E-51DBI50.57-1.3210.046.57
Golgin subfamily A member 527.960.001599558GOLGA59.41.3212.846.04
Hook homolog 135.650.00027227HOOK12.33-1.2879.975.19
UPF0459 protein C19orf5024.350.003672823KXD15.11-1.6419.664.89
LPS-responsive vesicle trafficking, beach and anchor containing123.344.63532E-13LRBA1.75-1.37286.795.52
28S ribosomal protein S16, mitochondrial56.672.15278E-06MRPS169.491.3815.349.50
28S ribosomal protein S17, mitochondrial80.199.5737E-09MRPS1715.381.3014.499.85
28S ribosomal protein S18b, mitochondrial93.794.17548E-10MRPS18B7.911.5024.348.56
myosin, light chain 6, alkali, smooth muscle and non-muscle497.531.76602E-50MYL646.67-1.2515.015.00
Myosin-Id149.001.25876E-15MYO1D2.49-1.30116.139.39
Ran-binding protein 646.972.00815E-05RANBP62.44-1.25124.635.01
Ammonium transporter Rh type B28.580.001386756RHBG11.341.2810.578.76
Secretory carrier-associated membrane protein 2135.772.64671E-14SCAMP23.951.6836.636.10
Mitochondrial glutamate carrier 184.113.8815E-09SLC25A224.641.2134.459.29
ADP/ATP translocase 21271.347.3482E-128SLC25A547.651.2432.839.69
spermatogenesis associated 729.050.001244515SPATA716.67-1.464.7610.26
Sarcalumenin23.750.004221453SRL2.32-1.7149.786.95
Serine/threonine-protein kinase WNK131.000.000794328WNK10.712.19206.527.15

Note: The asterisk (*) indicates the proteins discussed in the manuscript.

TMT labeled proteins identified by MS and organized according to biological processes.

Fig 1 shows proteins up-regulated or down-regulated at least 1.2 fold in C4-2 cells treated with 20 μg/ml MSKE as identified by the MASCOT database. Note: The asterisk (*) indicates the proteins discussed in the manuscript. Among the proteins that were differentially expressed, ER stress markers, such as 78 kDa glucose-regulated protein (GRP78) and protein disulfide isomerase A4 and A6 (PDIA4, PDIA6), as well as oxidative stress markers sulfiredoxin (SRXN1) and ubiquinone (NDUFS1 and NDUFS3) were up-regulated. Additional ER stress-related proteins identified among the up-regulations are eukaryotic translation initiation factor 2B (eIF2B) and eukaryotic translation initiation factor 4 binding protein (eIF4EBP1) with a respective significant fold change of 1.5 and 1.3 and the protein disulfide isomerase (PDI) A4 and A6 with a differential expression of 1.21 and 1.26, respectively. Key differentially expressed proteins induced by MSKE in C4-2 cells included those associated with apoptosis (e.g., STEAP2, PDCD6, MTDH, RAB5B, cytochrome c oxidase), autophagy (e.g., ACIN1, PI4KA, PGK2, MTDH), cytoskeleton and protein transport (e.g., cortactin, taxilin, radixin, filamin B), among others (Table 1). Furthermore, C4-2 control cells had a higher percent of anti-apoptotic proteins compared to the MSKE-treated cells, suggesting that MSKE induces an ER stress/autophagy/apoptosis signature.

MSKE Induces Expression of ER Stress Mediated Pro-Apoptotic Response Proteins

Western blot was used to measure the expression of proteins associated with ER stress response. Key ER stress response markers IRE-1 alpha and GRP78 (Fig 2) were up-regulated when compared to control cells. Apoptotic markers PARP, caspase-12 and DFF45 (Fig 2) were up-regulated in cells exposed to MSKE. These data suggest that MSKE may induce ER stress and UPR-mediated apoptosis.
Fig 2

Quantitative Western blot of key ER stress markers.

Western blot analysis in C4-2 cells treated with 20 μg/ml MSKE as compared to ethanol-treated controls. As a loading control total protein from Ponceau S staining was assessed. Expression of ER stress markers IRE1-alpha and GRP78 and pro-apoptotic markers DFF45, PARP and caspase-12 was analyzed and quantification of western blot analysis performed using Image J, NIH. The standard deviation was used to assess data dispersion.

Quantitative Western blot of key ER stress markers.

Western blot analysis in C4-2 cells treated with 20 μg/ml MSKE as compared to ethanol-treated controls. As a loading control total protein from Ponceau S staining was assessed. Expression of ER stress markers IRE1-alpha and GRP78 and pro-apoptotic markers DFF45, PARP and caspase-12 was analyzed and quantification of western blot analysis performed using Image J, NIH. The standard deviation was used to assess data dispersion.

MSKE Treatment Induces Autophagy

Since MSKE induced expression of ER stress response proteins, we sought to determine if treatment with MSKE induces autophagy. We treated C4-2 cells with 5, 10 or 20 μg/ml MSKE for 72 h and stained with acridine orange. Treatment with higher concentrations of MSKE (10 and 20 μg/mL) showed extensive acridine orange leakage into the cytosol (orange staining), indicating that MSKE induces autophagy (Fig 3A). Since the 20 μg/mL MSKE treatment showed extensive acridine orange staining we decided to see if co-treatment with chloroquine, a known autophagy inhibitor would reverse the effects of MSKE on C4-2 cells. Co-treatment with 20 μg/mL MSKE and 20 μM chloroquine lead to a decrease in acridine orange staining compared to 20 μg/mL MSKE alone, indicating that MSKE may promote autophagy (Fig 3B). To further validate a role for MSKE in autophagy, we also performed immunofluorescence and western blot with the autophagic marker, LC3B. There was increased punctate staining for LC3B in MSKE plus chloroquine co-treatments, which indicates that chloroquine prevents fusion of autophagosomes to lysosomes, and thus causes an accumulation of autophagosomes (Fig 3C). Similarly, western blot analysis showed increased LC3BII expression in MSKE plus chloroquine treatments indicating that chloroquine had inhbitied MSKE-mediated autophagy and caused accumulation of LC3BII lipidation products (Fig 3D). Of note, we did not observe increased LC3BII with MSKE treatment alone (Fig 3D), possibly due to high autophagic flux that can sometimes not be detected unless one includes an autophagy inhibitor as previously reported [16].
Fig 3

MSKE treatment induces autophagy.

(A) C4-2 prostate cancer cells were treated with MSKE (0 μg/mL, 5 μg/mL, 10 μg/mL, and 20 μg/mL) for 72 h. Fixation was performed with methanol/ethanol 1:1 volume followed by washes with 1× PBS. The cells were then exposed to acridine orange (5 μg/ml) for 15 min at 37°C, followed by washes with 1× PBS, prior to counterstaining with DAPI. We observed that treatment with higher concentrations of MSKE (10 and 20μg/ml) showed extensive acridine orange leakage into the cytosol, producing a diffuse yellow color and an increase in lysosomes indicating that MSKE induces cell death via autophagy compared to control. (B) C4-2 cells were treated with MSKE, with and without 20 μM chloroquine, for 72 h. The cells were then exposed to acridine orange (5 μg/ml) for 15 min at at 37°C, followed by washes with 1× PBS, prior to counterstaining with DAPI. Chloroquine treatment reversed the effects of MSKE. (C) Immunofluorescence staining for LC3B was performed on C4-2 cells treated with MSKE plus or minus chloroquine for 72 h. (D) Western blot analysis for LC3B was performed on C4-2 cells treated with MSKE plus/minus chloroquine. Image J analysis was performed to plot the ratios of LC3BI and LC3BII relative to actin loading control. The results are representative of experiments that have been performed in triplicate at least two times independently. Graphical data represents three independent experiments; * means 0.05 > p value > 0.01, ** means 0.01 > p value > 0.001.

MSKE treatment induces autophagy.

(A) C4-2 prostate cancer cells were treated with MSKE (0 μg/mL, 5 μg/mL, 10 μg/mL, and 20 μg/mL) for 72 h. Fixation was performed with methanol/ethanol 1:1 volume followed by washes with 1× PBS. The cells were then exposed to acridine orange (5 μg/ml) for 15 min at 37°C, followed by washes with 1× PBS, prior to counterstaining with DAPI. We observed that treatment with higher concentrations of MSKE (10 and 20μg/ml) showed extensive acridine orange leakage into the cytosol, producing a diffuse yellow color and an increase in lysosomes indicating that MSKE induces cell death via autophagy compared to control. (B) C4-2 cells were treated with MSKE, with and without 20 μM chloroquine, for 72 h. The cells were then exposed to acridine orange (5 μg/ml) for 15 min at at 37°C, followed by washes with 1× PBS, prior to counterstaining with DAPI. Chloroquine treatment reversed the effects of MSKE. (C) Immunofluorescence staining for LC3B was performed on C4-2 cells treated with MSKE plus or minus chloroquine for 72 h. (D) Western blot analysis for LC3B was performed on C4-2 cells treated with MSKE plus/minus chloroquine. Image J analysis was performed to plot the ratios of LC3BI and LC3BII relative to actin loading control. The results are representative of experiments that have been performed in triplicate at least two times independently. Graphical data represents three independent experiments; * means 0.05 > p value > 0.01, ** means 0.01 > p value > 0.001.

MSKE Promotes Autophagy-Mediated Apoptosis

To confirm that MSKE causes apoptosis, we treated the C4-2 cells with 5, 10, or 20 μg/ml MSKE and performed a TUNEL assay. Increased TUNEL staining (green) was observed with higher doses of MSKE (Fig 4A). These findings correlate with the Western blot analysis where up-regulation of pro-apoptotic markers PARP and caspase-12 was observed (Fig 2). These results support the hypothesis that MSKE induces apoptosis in C4-2 prostate cancer cells. To support the findings in the TUNEL assay and show that there was a correlation between autophagy and apoptosis, we performed quantitative apoptosis assay using flow cytometry via the Alexa Fluor 488 Annexin V in the presence or absence of chloroquine (autophagy inhibitor). Graphical representation of the apoptosis assay showed that treatment with MSKE led to an increase of apoptosis which was abrogated by treatment with chloroquine (Fig 4B). Western blot analysis confirmed these findings by showing that MSKE-mediated increase in pro-apoptotic proteins BAX, cleaved caspase-3 and -7, and decrease in anti-apoptotic protein BCL2 was abrogated by co-treatment with chloroquine (Fig 4C and 4D). Therefore, MSKE-mediated autophagy leads to apoptosis.
Fig 4

MSKE induces autophagy-mediated apoptosis.

(A) C4-2 prostate cancer cells were treated with increasing concentrations of 0μ g/mL, 5 μg/mL, 10 μg/mL, and 20 μg/mL for 72 h. The cells were fixed with 4% paraformaldehyde and permeabilized with 0.1% sodium citrate and 0.1% Triton X. DNA fragmentation was determined by TdT-mediated dUTP nick end labeling (TUNEL). TUNEL assay (green channel). DAPI (blue channel) is used to locate the nuclei of the cells. (B) Cells were stained with Annexin V- Alexa Fluor 488 and PI and analyzed by flow cytometry following treatment with 5 μg/mL MSKE with or without 20 μM chloroquine. Percent of cells in the lower right quadrant that represent Annexin V +/PI- or early apoptotis and cells in the upper right quadrant that represent Annexin V +/PI+ or late apoptotis was graphed. (C) Western blot analysis was performed to examine pro-apoptotic markers (Bax, cleaved caspase-3 and -7) and anti-apoptotic marker (BCL2) following treatment with MSKE in the presence or absence of 20 μM chloroquine. Actin was utilized as a loading control. (D) Results of western blot were analyzed using Image J and graphed. The experiments were performed in triplicate at least two times independently. Graphical data represents three independent experiments; * means 0.05 > p value > 0.01, ** means 0.01 > p value > 0.001, and *** means p value < 0.001.

MSKE induces autophagy-mediated apoptosis.

(A) C4-2 prostate cancer cells were treated with increasing concentrations of 0μ g/mL, 5 μg/mL, 10 μg/mL, and 20 μg/mL for 72 h. The cells were fixed with 4% paraformaldehyde and permeabilized with 0.1% sodium citrate and 0.1% Triton X. DNA fragmentation was determined by TdT-mediated dUTP nick end labeling (TUNEL). TUNEL assay (green channel). DAPI (blue channel) is used to locate the nuclei of the cells. (B) Cells were stained with Annexin V- Alexa Fluor 488 and PI and analyzed by flow cytometry following treatment with 5 μg/mL MSKE with or without 20 μM chloroquine. Percent of cells in the lower right quadrant that represent Annexin V +/PI- or early apoptotis and cells in the upper right quadrant that represent Annexin V +/PI+ or late apoptotis was graphed. (C) Western blot analysis was performed to examine pro-apoptotic markers (Bax, cleaved caspase-3 and -7) and anti-apoptotic marker (BCL2) following treatment with MSKE in the presence or absence of 20 μM chloroquine. Actin was utilized as a loading control. (D) Results of western blot were analyzed using Image J and graphed. The experiments were performed in triplicate at least two times independently. Graphical data represents three independent experiments; * means 0.05 > p value > 0.01, ** means 0.01 > p value > 0.001, and *** means p value < 0.001.

Discussion

We investigated the impact of MSKE on the C4-2 proteome using a quantitative TMT isobaric labeling approach with subsequent protein identification by mass spectrometry. Changes in C4-2 cells were also examined by Western blot. Autophagy and apoptosis were determined by acridine orange, TUNEL/Annexin V analyses, respectively. The results indicated that MSKE significantly regulated components of the UPR stress inducing pathways that include chaperones, ER stress antioxidant enzymes, proteolytic enzymes, cytoskeletal proteins, as well as enzymes involved in autophagy or apoptosis. Autophagy is a dynamic process, whereby cytoplasmic proteins and cellular organelles are enveloped in autophagosomes and degraded by fusion with lysosomes for amino acid and energy recycling [17]. There is evidence that autophagy can play a critical role in cellular survival [18] but, it is frequently activated in tumor cells following anticancer therapies such as drug treatment and gamma-irradiation [19]. Apoptosis is defined as an active, fixed-pathway process of cell death characterized by cell shrinking, cytoplasmic condensation, ladder DNA degradation, and nuclear fragmentation resulting in the formation of apoptotic bodies. Initial studies on the mechanism of action of MSKE, suggest the ability to induce apoptosis via activation of the caspase cascade. The increase of apoptosis after MSKE treatment was confirmed with the TUNEL and Annexin V assays, in agreement with previous studies that have shown that MSKE promotes apoptosis in prostate cancer cells [7]. Our current study identified several proteins associated with apoptosis triggered by MSKE treatment such as STEAP2, PDCD6, MTDH, RAB5B, and cytochrome C oxidase (Table 1). STEAP2, also known as 6-transmembrane protein of the prostate 1 (STAMP1) is overexpressed in several types of human cancers, namely prostate, bladder, colon, pancreas, ovary, testis, breast, and cervix, but its clinical significance and role in cancer cells is still unclear [20]. STEAP2 participates in a wide range of biological processes, including molecular trafficking in the endocytic and exocytic pathways. It also controls cell proliferation and apoptosis. STEAP2 was down-regulated in C4-2 cells. It has been shown that STEAP2 blockage has a pro-apoptotic role that causes mitochondrial damage, and decreases cell proliferation and glucose uptake [20]. MTDH was up-regulated by 1.91 fold upon MSKE treatment in C4-2 cells. MTDH has been proposed to promote tumor progression through the integration of multiple signaling pathways including ras, myc, Wnt, PI3K/AKT, and NF-κB in various types of cancer [21-24]. The nuclear protein Apoptotic Chromatin Condensation Inducer 1 (ACIN1) is known to function in DNA fragmentation and is activated during apoptosis by caspase-3. It also plays an active role in spliceosome assembly because it is a critical subunit of an apoptosis and splicing-associated protein (ASAP) complex [25,26]. ACIN1 was down-regulated in our study by -1.60 fold and we speculate that MSKE induced an anti-apoptotic/survival response in C4-2 cells by down-regulating ACIN1. Taxilin protein (TXLNA), a binding partner of the syntaxin family that functions as a central player in the intracellular vesicle traffic, and is a marker of testicular injury [27] was also upregulated upon MSKE treatment. Several results support the induction of apoptosis by MSKE via autophagy. The acridine orange staining showed that induced autophagy increased with MSKE treatment in a dose-dependent manner. Additionally, ER stress was significantly induced upon MSKE treatment in C4-2 cells as seen in the up-regulation of several stress-related proteins (e.g., GRP78, PDIA4, PDIA6, eIF2B, eIF4EBP1). We also identified COL4A3BP whose down-regulation sensitizes cancer cells to multiple cytotoxic agents, potentiating ER stress [28]. Lysosomal inhibitors such as chloroquine that inhibit acidification inside the lysosome or inhibit autophagosome-lysosome fusion and can block the degradation of LC3BII, leading to the accumulation of LC3BII, are good indicators for autophagy [29]. Co-treatment with MSKE plus chloroquine in C4-2 cells increased LC3B punctate staining as shown by immunofluorescence, and increased LC3-BII expression as shown by western blot analysis, proving that MSKE promotes autophagy which is blocked by chloroquine leading to accumulation of LC3BII. We speculated, however, that at 72 h we failed to see increased LC3BII with MSKE treatment alone due to high autophagic flux. This problem that sometimes arises when LC3BII expression does not increase when assayed at a certain time point as expected due to high autophagic flux is discussed in great detail with the conclusion that it is better to gauge autophagy by examining autophagosome accumulation in the presence of chloroquine [16]. We also demonstrated that chloroquine was able to reverse the extensive acridine orange leakage into the cytosol. Degradation of cytosolic proteins in lysosomes is a hallmark of autophagy [30]. The absence of chromatin condensation is another characteristic of autophagy and indicative of apoptosis [31]. Recent studies have shown that a variety of anticancer therapies (including those that stimulate ER stress) activate autophagy in tumor cells, which has been proposed to either enhance cancer cell death or act as a mechanism of resistance to chemotherapy [32]. Autophagy works as a tumor suppression mechanism by removing damaged organelles/proteins, limiting cell growth and minimizing genomic instability [33]. Phosphatidylinositol 4-Kinase (PI4KA), a protein involved in both nonselective and selective types of autophagy [34], was up-regulated in MSKE-treated C4-2 cells. The expression of metadherin (MTDH), also known as astrocyte-elevated gene-1, a protein that may protect normal cells from serum starvation-induced death through protective autophagy [35], increased 1.91 fold in the presence of MSKE. In addition, phosphoglycerate kinase (PGK2), a cytosolic and glycolytic marker, was down-regulated by MSKE in C4-2 cells, suggesting that it may have been taken up into autophagic bodies [36]. ER stress was evident by the up-regulation of key ER stress markers like GRP78 and PDIA4, A6. Proper protein folding, maturation, and stabilization of the nascent protein in the ER requires a highly oxidizing ER environment, which is essential for the diverse post-translational and co-translational modifications (e.g., glycosylation, disulfide bridge formation) to which proteins are subjected after entering the ER. These processes are assisted and monitored by several resident chaperones and binding proteins, including glucose-regulated proteins like GRP78, which was up-regulated in the presence of MSKE. Folding enzymes, such as the thioredoxin-like protein (PDI), oxidize cysteine residues in nascent proteins (i.e., oxidative folding) resulting in the formation of intra- and intermolecular disulfide bonds. MSKE resulted in ER stress pathway activation and subsequent translation initiation component activation (i.e., eIF4EPB, eIF2). Moreover, the upregulation of pro-apoptotic markers MTDH, caspase 12, Cytochrome C oxidase, PDCD6 and NQO1, along with the increased apoptosis visualized by TUNEL and Annexin V staining, suggest that the ER stress response might eventually trigger apoptosis. Overexpression of MTDH, also known as LYRIC, is observed in a variety of cancers and is involved in cancer initiation, proliferation, invasion, metastasis and chemoresistance [37]. MTDH also activates the PI3K/Akt pro-apoptotic pathway in cancer [38] and its inhibition induces apoptosis in prostate cancer cells [39]. Hudson et al. have also shown that treatment with MSKE activates the PI3K/Akt pro-apoptotic pathway in prostate cancer cells [7]. The upregulation of cytoplasmic C oxidase and Glyoxalase I (GLO1) suggests that MSKE also interferes with glycolysis and mitochondrial metabolism in C4-2 cells. GLO1 is a ubiquitous cellular defense enzyme involved in detoxification. GLO1 expression may protect cells against methylglyoxal-dependent protein adduction and cellular damage associated with diabetes, cancer, and chronological aging. GLO1 upregulation has been shown to play a pivotal role in glycolytic adaptations of cancer cells [40]. Phosphoglycerate kinase, a protein encoded by the PGK1 and PGK2 genes, is a glycolytic protein activated by MSKE. Phosphoglycerate kinase converts 1,3-diphosphoglycerate into 3-phosphoglycerate in the glycolysis pathway. PGK1 is located on the X chromosome and is ubiquitously expressed whereas PGK2, whose differential expression was induced by MSKE in C4-2 cells, is a retrotransposed copy of PGK1 located on chromosome 6 that shows a testis specific expression pattern [41,42]. Our analyses demonstrated overexpression of HYOU1, CTTN and DPYSL5, and down-regulation of ABCA5 proteins in C4-2 cells. These proteins have been implicated in other cancer cells and tumor types and are involved in relevant cell mechanisms for apoptosis evasion, increased tumor invasiveness, tumor hypoxia, cellular respiration, and mitochondrial fragmentation. ABCA5 is a member of the ATP-binding cassette transporter 1 subfamily of genes whose mutations are linked to several human genetic disorders including cystic fibrosis, neurological disease, retinal degeneration, cholesterol and bile transport defects, anemia, and drug response phenotypes [43]. MSKE also activates oxidative stress and ROS pathways through aldehyde dehydrogenases (ALD), sideroflexin, sulfiredoxin and DHRS1. ALDH belongs to a group of NAD(P)+-dependent enzymes involved in oxidation of a large number of aldehydes into their weak carboxylic acids [44]. ALDH is important for drug resistance, cell proliferation, differentiation, and response to oxidative stress in prostate cancer and its activity is used to distinguish between normal cells and their malignant counterparts. In a previous study, high ALDH activity was used to isolate human prostate cancer cells with significantly enhanced clonogenic and migratory properties both in vitro and in vivo. As seen in other cancer tissues, the percentage of ALDH cells in prostate cancer cell lines are also related to tumorigenicity and metastatic behavior [45]. MSKE induced apoptosis via the up-regulation of ER stress-driven caspase-3,-7 and -12. Treatment with chloroquine blocked the effects of MSKE on apoptosis by up-regulating BCL-2, decreasing BAX, preventing the cleavage of caspase-3 and -7 and antagonizing MSKE-mediated increase in early and late apoptosis. This further supports the findings that MSKE-mediated autophagy leads to apoptosis. MSKE also prompted the down-regulation of anti-apoptotic and survival proteins like Annexin A4 (ANXA4), a member of the Ca2+-regulated and phospholipid-binding annexin superfamily. ANXA4 expression is increased in many cancer types, including cancers of renal, gastric, colonic, ovarian, and cervical origins [46-50]. Its expression has been linked to loss of cell-to-cell adhesion, increased metastasis, and chemo-resistance, and it is considered a potential cancer diagnostic and therapeutic target [51,52]. In vitro studies suggest that ANXA4 exhibits an anti-apoptotic effect by activating NF-κB transcriptional activity [53,54]. Our data suggests that MSKE may induce apoptosis by decreasing ANXA4, and increasing MTDH. Recently, the cross-talk between autophagy and apoptosis has been considered as a key factor in the development and treatment of cancer [55]. The two pathways share molecular regulators and, in some cases, are activated by the same stimulus. Taken together, the results of this study suggest that MSKE induces apoptosis through signaling pathways that modulate ER stress, autophagy, cytoskeletal changes, cell-matrix, and cell-cell adhesion, as well as glycolysis and mitochondrial metabolism (Fig 5); opening the door to novel therapeutic and clinical exploitations.
Fig 5

Proposed model highlighting unfolded protein response pathway with pro-apoptotic protein signatures triggered by ER stress in MSKE treated C4-2 prostate cancer cells.

MSKE treatment of C4-2 cells promoted an unfolded protein response (UPR) pathway in a mitochondria-specific stress response (UPRmt) with pro- and anti-apoptotic protein signature triggered by ER stress. Strong ER stress and activation of the UPR initiate apoptosis. In contrast, mild UPR activation induces a beneficial ER homeotic response by reducing the load of misfolded proteins and by activating cellular protective mechanisms like autophagy. PERK mediates phosphorylation of eIF2α and ATF4-dependent transcriptional activation of autophagy proteins. The model highlights insufficient folding or degradation capacity in the mitochondria, contributing to apoptosis.

Proposed model highlighting unfolded protein response pathway with pro-apoptotic protein signatures triggered by ER stress in MSKE treated C4-2 prostate cancer cells.

MSKE treatment of C4-2 cells promoted an unfolded protein response (UPR) pathway in a mitochondria-specific stress response (UPRmt) with pro- and anti-apoptotic protein signature triggered by ER stress. Strong ER stress and activation of the UPR initiate apoptosis. In contrast, mild UPR activation induces a beneficial ER homeotic response by reducing the load of misfolded proteins and by activating cellular protective mechanisms like autophagy. PERK mediates phosphorylation of eIF2α and ATF4-dependent transcriptional activation of autophagy proteins. The model highlights insufficient folding or degradation capacity in the mitochondria, contributing to apoptosis.

Differentially expressed proteins in MSKE-treated and control cultures.

Detailed information including protein ID, gene name, number of amino acids, molecular weight, calculated pI, description, coverage samples, protein expression, change folds, and p-values. (XLSX) Click here for additional data file.
  54 in total

1.  A novel response of cancer cells to radiation involves autophagy and formation of acidic vesicles.

Authors:  S Paglin; T Hollister; T Delohery; N Hackett; M McMahill; E Sphicas; D Domingo; J Yahalom
Journal:  Cancer Res       Date:  2001-01-15       Impact factor: 12.701

Review 2.  The human ATP-binding cassette (ABC) transporter superfamily.

Authors:  M Dean; Y Hamon; G Chimini
Journal:  J Lipid Res       Date:  2001-07       Impact factor: 5.922

3.  Methods in mammalian autophagy research.

Authors:  Noboru Mizushima; Tamotsu Yoshimori; Beth Levine
Journal:  Cell       Date:  2010-02-05       Impact factor: 41.582

4.  Antioxidant Activity of Berry and Fruit Wines and Liquors.

Authors: 
Journal:  J Agric Food Chem       Date:  1998-01-19       Impact factor: 5.279

5.  Proteomic characterization of ovarian cancers identifying annexin-A4, phosphoserine aminotransferase, cellular retinoic acid-binding protein 2, and serpin B5 as histology-specific biomarkers.

Authors:  Atsuhiko Toyama; Atsushi Suzuki; Takashi Shimada; Chikage Aoki; Yutaka Aoki; Yukari Umino; Yusuke Nakamura; Daisuke Aoki; Taka-Aki Sato
Journal:  Cancer Sci       Date:  2012-02-20       Impact factor: 6.716

6.  Increased expression and altered location of annexin IV in renal clear cell carcinoma: a possible role in tumour dissemination.

Authors:  Uwe Zimmermann; Stefan Balabanov; Jürgen Giebel; Steffen Teller; Heike Junker; Dieter Schmoll; Chris Protzel; Christian Scharf; Britta Kleist; Reinhard Walther
Journal:  Cancer Lett       Date:  2004-06-08       Impact factor: 8.679

7.  Astrocyte elevated gene-1 activates cell survival pathways through PI3K-Akt signaling.

Authors:  S-G Lee; Z-Z Su; L Emdad; D Sarkar; T F Franke; P B Fisher
Journal:  Oncogene       Date:  2007-08-20       Impact factor: 9.867

8.  AEG-1 expression characteristics in human non-small cell lung cancer and its relationship with apoptosis.

Authors:  Zun-Fu Ke; Xiaopeng Mao; Cao Zeng; Shanyang He; Shuhua Li; Lian-Tang Wang
Journal:  Med Oncol       Date:  2013-01-10       Impact factor: 3.064

9.  Proteomic analysis of acquired tamoxifen resistance in MCF-7 cells reveals expression signatures associated with enhanced migration.

Authors:  Changhua Zhou; Qiu Zhong; Lyndsay V Rhodes; Ian Townley; Melyssa R Bratton; Qiang Zhang; Elizabeth C Martin; Steven Elliott; Bridgette M Collins-Burow; Matthew E Burow; Guangdi Wang
Journal:  Breast Cancer Res       Date:  2012-03-14       Impact factor: 6.466

10.  Unique and differential protein signatures within the mononuclear cells of HIV-1 and HCV mono-infected and co-infected patients.

Authors:  Nawal M Boukli; Vivekananda Shetty; Luis Cubano; Martha Ricaurte; Jordana Coelho-Dos-Reis; Zacharie Nickens; Punit Shah; Andrew H Talal; Ramila Philip; Pooja Jain
Journal:  Clin Proteomics       Date:  2012-09-07       Impact factor: 3.988

View more
  18 in total

1.  Essential role of JunD in cell proliferation is mediated via MYC signaling in prostate cancer cells.

Authors:  Bethtrice Elliott; Ana Cecilia Millena; Lilya Matyunina; Mengnan Zhang; Jin Zou; Guangdi Wang; Qiang Zhang; Nathan Bowen; Vanessa Eaton; Gabrielle Webb; Shadyra Thompson; John McDonald; Shafiq Khan
Journal:  Cancer Lett       Date:  2019-02-11       Impact factor: 8.679

2.  The ER-localized Ca2+-binding protein calreticulin couples ER stress to autophagy by associating with microtubule-associated protein 1A/1B light chain 3.

Authors:  Yunzhi Yang; Fengguang Ma; Zhengshuai Liu; Qian Su; Yuxiao Liu; Zhixue Liu; Yu Li
Journal:  J Biol Chem       Date:  2018-11-14       Impact factor: 5.157

3.  PPARδ is a regulator of autophagy by its phosphorylation.

Authors:  Qian Gou; Yidan Jiang; Runyun Zhang; Ying Xu; Huihui Xu; Wenbo Zhang; Juanjuan Shi; Yongzhong Hou
Journal:  Oncogene       Date:  2020-05-21       Impact factor: 9.867

4.  Grape Powder Supplementation Attenuates Prostate Neoplasia Associated with Pten Haploinsufficiency in Mice Fed High-Fat Diet.

Authors:  Tanvi Joshi; Ishani Patel; Avinash Kumar; Virginia Donovan; Anait S Levenson
Journal:  Mol Nutr Food Res       Date:  2020-07-12       Impact factor: 5.914

Review 5.  The endoplasmic reticulum stress response in prostate cancer.

Authors:  Claire M de la Calle; Kevin Shee; Heiko Yang; Peter E Lonergan; Hao G Nguyen
Journal:  Nat Rev Urol       Date:  2022-09-27       Impact factor: 16.430

6.  Muscadine Grape Skin Extract (MPX) in Men with Biochemically Recurrent Prostate Cancer: A Randomized, Multicenter, Placebo-Controlled Clinical Trial.

Authors:  Channing J Paller; Xian C Zhou; Elisabeth I Heath; Mary-Ellen Taplin; Tina Mayer; Mark N Stein; Glenn J Bubley; Roberto Pili; Tamaro Hudson; Radhika Kakarla; Muneer M Abbas; Nicole M Anders; Donna Dowling; Serina King; Ashley B Bruns; William D Wagner; Charles G Drake; Emmanuel S Antonarakis; Mario A Eisenberger; Samuel R Denmeade; Michelle A Rudek; Gary L Rosner; Michael A Carducci
Journal:  Clin Cancer Res       Date:  2017-11-07       Impact factor: 12.531

7.  Targeting multiple pro-apoptotic signaling pathways with curcumin in prostate cancer cells.

Authors:  Mariela Rivera; Yanilda Ramos; Madeline Rodríguez-Valentín; Sheila López-Acevedo; Luis A Cubano; Jin Zou; Qiang Zhang; Guangdi Wang; Nawal M Boukli
Journal:  PLoS One       Date:  2017-06-19       Impact factor: 3.240

8.  Effect of Ball Mill Treatment on the Physicochemical Properties and Digestibility of Protein Extracts Generated from Scallops (Chlamys farreri).

Authors:  Di Wu; Chao Wu; Hui Chen; Zhenyu Wang; Cuiping Yu; Ming Du
Journal:  Int J Mol Sci       Date:  2018-02-09       Impact factor: 5.923

Review 9.  The impact of moderate wine consumption on the risk of developing prostate cancer.

Authors:  Mihai Dorin Vartolomei; Shoji Kimura; Matteo Ferro; Beat Foerster; Mohammad Abufaraj; Alberto Briganti; Pierre I Karakiewicz; Shahrokh F Shariat
Journal:  Clin Epidemiol       Date:  2018-04-17       Impact factor: 4.790

10.  HIV-1 Gp120 clade B/C induces a GRP78 driven cytoprotective mechanism in astrocytoma.

Authors:  Sheila N López; Madeline Rodríguez-Valentín; Mariela Rivera; Maridaliz Rodríguez; Mohan Babu; Luis A Cubano; Huangui Xiong; Guangdi Wang; Lilia Kucheryavykh; Nawal M Boukli
Journal:  Oncotarget       Date:  2017-07-22
View more

北京卡尤迪生物科技股份有限公司 © 2022-2023.