Worapong Khaodee1, Nichanan Inboot1, Suruk Udomsom2,3, Warunee Kumsaiyai1, Ratchada Cressey4,5. 1. Division of Clinical Chemistry, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand. 2. Biomedical Engineering Program, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand. 3. Biomedical Engineering Center, Chiang Mai University, Chiang Mai, Thailand. 4. Division of Clinical Chemistry, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand. Ratchada.cr@cmu.ac.th. 5. MT Cancer Research Unit, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand. Ratchada.cr@cmu.ac.th.
Abstract
PURPOSE: Glucosidase II plays a major role in regulating the post-translational modification of N-linked glycoproteins. Previously, we found that the beta subunit of glucosidase II (GluIIβ) levels are significantly increased in lung carcinoma tissues, indicating a potential role in lung tumorigenesis. Here, we investigated the role of GluIIβ in the regulation of autophagy and apoptosis in lung carcinoma- and immortalized human bronchial epithelial-derived cells. METHODS: A selective glucosidase II inhibitor, bromoconduritol, was used to inhibit GluII enzyme activity and a siRNA-based technology was used to suppress the expression of the GluIIβ encoding gene PRKCSH in lung carcinoma cells differing in p53 status. Cell viability was assessed using a MTT assay, cell cycle progression was assessed using flow cytometry, autophagy was assessed using Western blotting and apoptosis was assessed using an annexin V-FITC/PI double labeling method. RESULTS: We found that GluIIβ inhibition resulted in the induction of autophagy in all cell lines tested, but apoptosis in only wild-type p53 cells. We also found that GluIIβ inhibition dose-dependently decreased activation of the EGFR/RTK and PI3K/AKT signaling pathways. Although the apoptosis inducing effect of GluIIβ inhibition appeared to be p53-dependent, we found that a combined treatment with lysosomal inhibitors to block autophagy enhanced the apoptotic effect of GluIIβ inhibition in both wild-type p53 and p53-null cells. CONCLUSIONS: Our data indicate that GluIIβ inhibition results in autophagy and apoptosis in lung carcinoma-derived cells, supporting the hypothesis that this enzyme may play a role in blocking these two tumor suppressive processes. Since blocking autophagy by lysosomal inhibitors enhanced the apoptosis-inducing effect of bromoconduritol, independent of p53 status, their combined use may hold promise for the treatment of cancer, particularly lung cancer.
PURPOSE: Glucosidase II plays a major role in regulating the post-translational modification of N-linked glycoproteins. Previously, we found that the beta subunit of glucosidase II (GluIIβ) levels are significantly increased in lung carcinoma tissues, indicating a potential role in lung tumorigenesis. Here, we investigated the role of GluIIβ in the regulation of autophagy and apoptosis in lung carcinoma- and immortalized human bronchial epithelial-derived cells. METHODS: A selective glucosidase II inhibitor, bromoconduritol, was used to inhibit GluII enzyme activity and a siRNA-based technology was used to suppress the expression of the GluIIβ encoding gene PRKCSH in lung carcinoma cells differing in p53 status. Cell viability was assessed using a MTT assay, cell cycle progression was assessed using flow cytometry, autophagy was assessed using Western blotting and apoptosis was assessed using an annexin V-FITC/PI double labeling method. RESULTS: We found that GluIIβ inhibition resulted in the induction of autophagy in all cell lines tested, but apoptosis in only wild-type p53 cells. We also found that GluIIβ inhibition dose-dependently decreased activation of the EGFR/RTK and PI3K/AKT signaling pathways. Although the apoptosis inducing effect of GluIIβ inhibition appeared to be p53-dependent, we found that a combined treatment with lysosomal inhibitors to block autophagy enhanced the apoptotic effect of GluIIβ inhibition in both wild-type p53 and p53-null cells. CONCLUSIONS: Our data indicate that GluIIβ inhibition results in autophagy and apoptosis in lung carcinoma-derived cells, supporting the hypothesis that this enzyme may play a role in blocking these two tumor suppressive processes. Since blocking autophagy by lysosomal inhibitors enhanced the apoptosis-inducing effect of bromoconduritol, independent of p53 status, their combined use may hold promise for the treatment of cancer, particularly lung cancer.
Authors: Joseph N Contessa; Mahaveer S Bhojani; Hudson H Freeze; Alnawaz Rehemtulla; Theodore S Lawrence Journal: Cancer Res Date: 2008-05-15 Impact factor: 12.701
Authors: Yingwei Hu; Jianbo Pan; Punit Shah; Minghui Ao; Stefani N Thomas; Yang Liu; Lijun Chen; Michael Schnaubelt; David J Clark; Henry Rodriguez; Emily S Boja; Tara Hiltke; Christopher R Kinsinger; Karin D Rodland; Qing Kay Li; Jiang Qian; Zhen Zhang; Daniel W Chan; Hui Zhang Journal: Cell Rep Date: 2020-10-20 Impact factor: 9.423