Safiyeh Aghazadeh1, Razieh Yazdanparast2. 1. Institute of Biochemistry and Biophysics, University of Tehran, P. O. Box 13145-1384, Tehran, Iran. 2. Institute of Biochemistry and Biophysics, University of Tehran, P. O. Box 13145-1384, Tehran, Iran. Electronic address: ryazdan@ut.ac.ir.
Abstract
BACKGROUND: Resistance to the HER2-targeted antibody trastuzumab remains to be a major clinical challenge in the treatment of HER2-positive breast cancer. Hyper-activation of STAT3 is proposed to be a predictive biomarker of trastuzumab resistance. However, the precise mechanism(s) remains poorly defined. Evidence is emerging that HIF-1α, a central downstream element of STAT3 pathway, serves a pivotal role in the complex signaling network with subsequent diverse cellular events. MATERIAL AND METHODS: We have established trastuzumab resistant SKBR3 cells (SKBR3-TR). The cell viability, apoptosis as well as western blot, siRNA transfection and co-immunoprecipitation assays were performed to evaluate the involvement of STAT3/HIF-1α in modulation of trastuzumab resistance. RESULTS: We found that in SKBR3-TR cells and conditioned medium-treated parental cells, constitutive phosphorylated STAT3 coincided with prominent up-regulation of HIF-1α which was accompanied with PTEN attenuation. Moreover, the inhibition of STAT3 activation by Stattic and/or genetically STAT3 knocking down decreased HIF-1α level in SKBR3-TR cells. Additionally, treatment with Stattic and/or STAT3 siRNA engendered the up-regulation of PTEN protein in STAT3-inhibited resistant cells. Restoration of PTEN was also observed following siRNA-mediated silencing of HIF-1α expression. Moreover, down-regulation of HIF-1α caused a reduction in the HES-1 content. Further study with HES-1 specific siRNA revealed the elevation of PTEN expression in HES-1 knock-down trastuzumab resistant cells. CONCLUSION: The impairment of STAT3-HIF-1α-HES-1 pathway restored trastuzumab sensitivity through up-regulation of PTEN protein. GENERAL SIGNIFICANCE: These findings highlighted the signal integrator role of HIF-1α in STAT3-mediated trastuzumab resistance induction which would be valuable in designing more efficient chemosensitization strategies.
BACKGROUND: Resistance to the HER2-targeted antibody trastuzumab remains to be a major clinical challenge in the treatment of HER2-positive breast cancer. Hyper-activation of STAT3 is proposed to be a predictive biomarker of trastuzumab resistance. However, the precise mechanism(s) remains poorly defined. Evidence is emerging that HIF-1α, a central downstream element of STAT3 pathway, serves a pivotal role in the complex signaling network with subsequent diverse cellular events. MATERIAL AND METHODS: We have established trastuzumab resistant SKBR3 cells (SKBR3-TR). The cell viability, apoptosis as well as western blot, siRNA transfection and co-immunoprecipitation assays were performed to evaluate the involvement of STAT3/HIF-1α in modulation of trastuzumab resistance. RESULTS: We found that in SKBR3-TR cells and conditioned medium-treated parental cells, constitutive phosphorylated STAT3 coincided with prominent up-regulation of HIF-1α which was accompanied with PTEN attenuation. Moreover, the inhibition of STAT3 activation by Stattic and/or genetically STAT3 knocking down decreased HIF-1α level in SKBR3-TR cells. Additionally, treatment with Stattic and/or STAT3 siRNA engendered the up-regulation of PTEN protein in STAT3-inhibited resistant cells. Restoration of PTEN was also observed following siRNA-mediated silencing of HIF-1α expression. Moreover, down-regulation of HIF-1α caused a reduction in the HES-1 content. Further study with HES-1 specific siRNA revealed the elevation of PTEN expression in HES-1 knock-down trastuzumab resistant cells. CONCLUSION: The impairment of STAT3-HIF-1α-HES-1 pathway restored trastuzumab sensitivity through up-regulation of PTEN protein. GENERAL SIGNIFICANCE: These findings highlighted the signal integrator role of HIF-1α in STAT3-mediated trastuzumab resistance induction which would be valuable in designing more efficient chemosensitization strategies.
Authors: Xiaokai Ding; Amanda C Sharko; Martina S J McDermott; Gary P Schools; Alexander Chumanevich; Hao Ji; Jing Li; Li Zhang; Zachary T Mack; Vitali Sikirzhytski; Michael Shtutman; Laura Ivers; Norma O'Donovan; John Crown; Balázs Győrffy; Mengqian Chen; Igor B Roninson; Eugenia V Broude Journal: Proc Natl Acad Sci U S A Date: 2022-08-01 Impact factor: 12.779
Authors: Anna Barkovskaya; Kotryna Seip; Bylgja Hilmarsdottir; Gunhild M Maelandsmo; Siver A Moestue; Harri M Itkonen Journal: Sci Rep Date: 2019-04-05 Impact factor: 4.379