title: Proteasome inhibitor-I enhances tunicamycin-induced chemosensitization of prostate cancer cells through regulation of NF-κB and CHOP expression.
abstract: Although endoplasmic reticulum (ER) stress induction by some anticancer drugs can lead to apoptotic death of cancer cells, combination therapy with other chemicals would be much more efficient. It has been reported that proteasome inhibitors could induce cancer cell death through ER-stress. Our study, however, showed a differential mechanism of proteasome inhibitor-I (Pro-I)-induced cell death. Pro-I significantly enhanced apoptotic death of PC3 prostate cancer cells pretreated with tunicamycin (TM) while other signaling inhibitors against p38, mitogen activated kinase (MEK) and phosphatidyl-inositol 3-kinase (PI3K) did not, as evidenced by cell proliferation and cell cycle analyses. NF-κB inhibition by Pro-I, without direct effect on ER-stress, was found to be responsible for the TM-induced chemosensitization of PC3 cells. Moreover, TM-induced/enhancer-binding protein (C/EBP) homologous protein (CHOP) expression was enhanced by Pro-I without change in GRP78 expression. CHOP knockdown by siRNA also showed a significant decrease in Pro-I chemosensitization. All these data suggest that although TM could induce both NF-κB activation and CHOP expression through ER-stress, both NF-κB inhibition and increased CHOP level by Pro-I are required for enhanced chemosensitization of PC3 prostate cancer cells. Thus, our study might contribute to the identification of anticancer targets against prostate cancer cells.
authors.affiliation: Chemical Biology Research Center, Korea Research Institute of Bioscience and Biotechnology, 685-1 Yangcheonri, Ochangeup, Cheongwongun, 363-883, Republic of Korea.
authors.forename: Pham Thi Thu
authors.initials: PT
authors.lastname: Huong
authors.forename: Dong-Oh
authors.initials: DO
authors.lastname: Moon
authors.forename: Sun Ok
authors.initials: SO
authors.lastname: Kim
authors.forename: Kyoon Eon
authors.initials: KE
authors.lastname: Kim
authors.forename: Sook Jung
authors.initials: SJ
authors.lastname: Jeong
authors.forename: Ki Won
authors.initials: KW
authors.lastname: Lee
authors.forename: Kyung Sang
authors.initials: KS
authors.lastname: Lee
authors.forename: Jae Hyuk
authors.initials: JH
authors.lastname: Jang
authors.forename: Raymond Leo
authors.initials: RL
authors.lastname: Erikson
authors.forename: Jong Seog
authors.initials: JS
authors.lastname: Ahn
authors.forename: Bo Yeon
authors.initials: BY
authors.lastname: Kim
mesh_terms: D017209:Apoptosis; D049109:Cell Proliferation; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D006801:Humans; D008297:Male; D016328:NF-kappa B / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D051742:Transcription Factor CHOP / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014415:Tunicamycin / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; D016328:NF-kappa B; D009842:Oligopeptides; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D034741:RNA, Small Interfering; D051742:Transcription Factor CHOP; D014415:Tunicamycin; D048051:p38 Mitogen-Activated Protein Kinases; C000717247:HSPA5 protein, human; C090535:benzyloxycarbonyl-isoleucyl-glutamyl(O-tert-butyl)-alanyl-leucinal