title: Down-regulation of glucose-regulated protein (GRP) 78 potentiates cytotoxic effect of celecoxib in human urothelial carcinoma cells.
abstract: Celecoxib is a selective cyclooxygenase-2 (COX-2) inhibitor that has been reported to elicit anti-proliferative response in various tumors. In this study, we aim to investigate the antitumor effect of celecoxib on urothelial carcinoma (UC) cells and the role endoplasmic reticulum (ER) stress plays in celecoxib-induced cytotoxicity. The cytotoxic effects were measured by MTT assay and flow cytometry. The cell cycle progression and ER stress-associated molecules were examined by Western blot and flow cytometry. Moreover, the cytotoxic effects of celecoxib combined with glucose-regulated protein (GRP) 78 knockdown (siRNA), (-)-epigallocatechin gallate (EGCG) or MG132 were assessed. We demonstrated that celecoxib markedly reduces the cell viability and causes apoptosis in human UC cells through cell cycle G1 arrest. Celecoxib possessed the ability to activate ER stress-related chaperones (IRE-1α and GRP78), caspase-4, and CCAAT/enhancer binding protein homologous protein (CHOP), which were involved in UC cell apoptosis. Down-regulation of GRP78 by siRNA, co-treatment with EGCG (a GRP78 inhibitor) or with MG132 (a proteasome inhibitor) could enhance celecoxib-induced apoptosis. We concluded that celecoxib induces cell cycle G1 arrest, ER stress, and eventually apoptosis in human UC cells. The down-regulation of ER chaperone GRP78 by siRNA, EGCG, or proteosome inhibitor potentiated the cytotoxicity of celecoxib in UC cells. These findings provide a new treatment strategy against UC.
authors.affiliation: Graduate Institute of Toxicology, College of Medicine, National Taiwan University, and National Taiwan University Hospital, Taipei, Taiwan. kuohowhuang@gmail.com
authors.forename: Kuo-How
authors.initials: KH
authors.lastname: Huang
authors.forename: Kuan-Lin
authors.initials: KL
authors.lastname: Kuo
authors.forename: Shyh-Chyan
authors.initials: SC
authors.lastname: Chen
authors.forename: Te-I
authors.initials: TI
authors.lastname: Weng
authors.forename: Yuan-Ting
authors.initials: YT
authors.lastname: Chuang
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Tsai
authors.forename: Yeong-Shiau
authors.initials: YS
authors.lastname: Pu
authors.forename: Chih-Kang
authors.initials: CK
authors.lastname: Chiang
authors.forename: Shing-Hwa
authors.initials: SH
authors.lastname: Liu
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology; D000068579:Celecoxib; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology*; D015536:Down-Regulation; D004357:Drug Synergism; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007976:Leupeptins / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000235:genetics; D013312:Stress, Physiological / Q000187:drug effects; D013449:Sulfonamides / Q000494:pharmacology*; D056811:Unfolded Protein Response; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D007211:Indoles; C501175:LM-1685; D007976:Leupeptins; D011720:Pyrazoles; D034741:RNA, Small Interfering; D013449:Sulfonamides; D002392:Catechin; C045651:epigallocatechin gallate; D000068579:Celecoxib; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde