title: Expression of the inhibitors of apoptosis proteins in cisplatin-resistant prostate cancer cells.
abstract: Acquired multi-drug resistance remains a major obstacle in the management of prostate cancer. The objective of this study was to examine whether chemoresistance could be due in part to the expression of the inhibitors of apoptosis proteins (IAPs). We established cisplatin-resistant LNCaP sublines. We examined the effects of cisplatin on cell growth and apoptosis in LNCaP cells and LNCaP sublines by 2-(4-lodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt (WST-1) assay and Hoechst 33258 staining, and analyzed cross-resistance to adriamycin, 5-fluorouracil, taxol, taxotere, and etoposide. In addition, the expression of IAP-1, IAP-2, X-linked IAP (XIAP), neuronal apoptosis inhibitory protein, and survivin was investigated by immunoblot analysis in LNCaP sublines. Although the growth rates were reduced in a dose-dependent manner by cisplatin in LNCaP sublines, the anti-proliferative effects of cisplatin were significantly decreased in LNCaP sublines compared to LNCaP cells. Cisplatin-resistant sublines, LNCaP/C1, LNCaP/ C2, and LNCaP/C3 cells, were 6.3-, 9.1-, and 22.3-fold more resistant to cisplatin than LNCaP cells, respectively, and this resistance was paralleled with reduced induction of apoptosis. LNCaP/C3 cells showed cross-resistance to adriamycin, 5-fluorouracil, and etoposide whereas those cells exhibited no or only weak cross-resistance against taxol and taxotere. With the exception of survivin, all the IAPs were identified in LNCaP cells by immunoblot analysis. Interestingly, the expression of IAP-2, XIAP, and survivin gradually increased with the extent of cisplatin-resistance. Altered expression of IAP-2, XIAP, and survivin was involved in these phenotypes of cisplatin-resistant LNCaP sublines. IAPs may make an important contribution to the resistance to the apoptotic effect of cisplatin in prostate cancer.
authors.affiliation: Department of Oncological Science (Urology), Oita University Faculty of Medicine, Oita, Japan. tnomur2@emory.edu
authors.forename: Takeo
authors.initials: T
authors.lastname: Nomura
authors.forename: Mutsushi
authors.initials: M
authors.lastname: Yamasaki
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Nomura
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Mimata
mesh_terms: D017209:Apoptosis; D000075747:Baculoviral IAP Repeat-Containing 3 Protein; D006690:Bisbenzimidazole / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002945:Cisplatin / Q000378:metabolism / Q000494:pharmacology*; D000077143:Docetaxel; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D004351:Drug Resistance; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005047:Etoposide / Q000494:pharmacology; D005472:Fluorouracil / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D051034:Inhibitor of Apoptosis Proteins / Q000096:biosynthesis*; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D051616:Neuronal Apoptosis-Inhibitory Protein / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology; D010641:Phenotype; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D000077022:Survivin; D043823:Taxoids / Q000494:pharmacology; D013778:Tetrazolium Salts / Q000494:pharmacology; D013997:Time Factors; D044767:Ubiquitin-Protein Ligases; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000096:biosynthesis
chemical_list: C110656:2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D051616:Neuronal Apoptosis-Inhibitory Protein; D000077022:Survivin; D043823:Taxoids; D013778:Tetrazolium Salts; D051636:X-Linked Inhibitor of Apoptosis Protein; D000077143:Docetaxel; D005047:Etoposide; D004317:Doxorubicin; C494833:BIRC2 protein, human; C494832:BIRC3 protein, human; D000075747:Baculoviral IAP Repeat-Containing 3 Protein; D044767:Ubiquitin-Protein Ligases; D006690:Bisbenzimidazole; D017239:Paclitaxel; D002945:Cisplatin; D005472:Fluorouracil