title: Glycogen synthase kinase-3beta suppression eliminates tumor necrosis factor-related apoptosis-inducing ligand resistance in prostate cancer.
abstract: Prostate cancer is a major health threat for American men. Therefore, the development of effective therapeutic options is an urgent issue for prostate cancer treatment. In this study, we evaluated the effect of glycogen synthase kinase-3beta (GSK-3beta) suppression on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in human prostate cancer cell lines. In the presence of lithium chloride (LiCl) or SB216763, the GSK-3beta inhibitors, TRAIL-induced cell death was dramatically enhanced, and the enhanced cell death was an augmented apoptotic response evidenced by increased Annexin V labeling and caspase-3 activation. GSK-3beta gene silencing mediated by a small interference RNA (siRNA) duplex also sensitized the cells to TRAIL, confirming the specificity of GSK-3beta suppression. Importantly, TRAIL stimulation increased GSK-3beta tyrosine phosphorylation at Y216, suggesting that GSK-3beta is activated by TRAIL. Furthermore, TRAIL sensitization was associated with increased proteolytic procession of caspase-8 and its downstream target BID, and z-IETD-FMK, the inhibitor specific to active caspase-8 totally blocked LiCl-induced TRAIL sensitization. Finally, Trichodion, a potent nuclear factor-kappaB (NF-kappaB) inhibitor, could not affect LiCl-induced TRAIL sensitization, although GSK-3beta inhibitors significantly blocked TRAIL-reduced NF-kappaB activity in prostate cancer cells. These results indicate that GSK-3beta suppression sensitizes prostate cancer cells to TRAIL-induced apoptosis that is dependent on caspase-8 activities but independent of NF-kappaB activation, and suggest that a mechanism involving GSK-3beta activation may be responsible for TRAIL resistance in prostate cancer cells.
authors: Department of Urology and Kansas Cancer Institute, The University of Kansas Medical Center, Kansas City, KS, USA.
authors: Xinbo
authors: X
authors: Liao
authors: Liping
authors: L
authors: Zhang
authors: J Brantley
authors: JB
authors: Thrasher
authors: Jie
authors: J
authors: Du
authors: Benyi
authors: B
authors: Li
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D020868:Gene Silencing; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D018021:Lithium Chloride / Q000494:pharmacology; D008297:Male; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D011753:Pyrones / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D011753:Pyrones; D034741:RNA, Small Interfering; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; C412103:trichodion; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases; D018021:Lithium Chloride