title: Nitric oxide regulates cell sensitivity to cisplatin-induced apoptosis through S-nitrosylation and inhibition of Bcl-2 ubiquitination.
abstract: Cisplatin is a potent cytotoxic agent commonly used for the treatment of solid tumors. However, tumor cell-acquired resistance to cisplatin-induced apoptosis is a major limitation for efficient therapy, as frequently observed in human lung cancer. Nitric oxide (NO) is a key regulator of apoptosis, but its role in cisplatin-induced cell death and the underlying mechanism are largely unknown. Previous studies indicate increased NO synthase activity and elevated NO production in lung carcinomas, which correlate with the incidence of chemotherapeutic resistance. Here, we show that NO impairs the apoptotic function of cells and increases their resistance to cisplatin-induced cell death in human lung carcinoma H-460 cells. The NO donors sodium nitroprusside and dipropylenetriamine NONOate were able to inhibit cisplatin-induced cell death, whereas the NO inhibitors aminoguanidine and 2-(4-carboxyphenyl)-4,4,5,5-tetra-methylimidazoline-1-oxyl-3-oxide had opposite effect. Cisplatin resistance in H-460 cells is mediated by Bcl-2, and NO up-regulates its expression by preventing the degradation of Bcl-2 via ubiquitin-proteasome pathway. Cisplatin-induced generation of reactive oxygen species causes dephosphorylation and degradation of Bcl-2. In contrast, generation of NO has no effect on Bcl-2 phosphorylation but induces S-nitrosylation of the protein, which inhibits its ubiquitination and subsequent proteasomal degradation. These findings indicate a novel pathway for NO regulation of Bcl-2, which provides a key mechanism for cisplatin resistance and its potential modulation for improved cancer chemotherapy.
authors.affiliation: Department of Pharmaceutical Sciences and Mary Babb Randolph Cancer Center, West Virginia University, WV 26506, USA.
authors.forename: Pithi
authors.initials: P
authors.lastname: Chanvorachote
authors.forename: Ubonthip
authors.initials: U
authors.lastname: Nimmannit
authors.forename: Christian
authors.initials: C
authors.lastname: Stehlik
authors.forename: Liying
authors.initials: L
authors.lastname: Wang
authors.forename: Bing-Hua
authors.initials: BH
authors.lastname: Jiang
authors.forename: Boonsri
authors.initials: B
authors.lastname: Ongpipatanakul
authors.forename: Yon
authors.initials: Y
authors.lastname: Rojanasakul
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D006801:Humans; D009569:Nitric Oxide / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D010766:Phosphorylation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014452:Ubiquitins / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D014452:Ubiquitins; D009569:Nitric Oxide; D009584:Nitrogen; D002945:Cisplatin