title: Tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone promotes functional cooperation of Bcl2 and c-Myc through phosphorylation in regulating cell survival and proliferation.
abstract: Nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is formed by nitrosation of nicotine and has been identified as the most potent carcinogen contained in cigarette smoke. NNK significantly contributes to smoking-related lung cancer, but the molecular mechanism remains enigmatic. Bcl2 and c-Myc are two major oncogenic proteins that cooperatively promote tumor development. We report here that NNK simultaneously stimulates Bcl2 phosphorylation exclusively at Ser(70) and c-Myc at Thr(58) and Ser(62) through activation of both ERK1/2 and PKCalpha, which is required for NNK-induced survival and proliferation of human lung cancer cells. Treatment of cells with staurosporine or PD98059 blocks both Bcl2 and c-Myc phosphorylation and results in suppression of NNK-induced proliferation. Specific depletion of c-Myc expression by RNA interference retards G(1)/S cell cycle transition and blocks NNK-induced cell proliferation. Phosphorylation of Bcl2 at Ser(70) promotes a direct interaction between Bcl2 and c-Myc in the nucleus and on the outer mitochondrial membrane that significantly enhances the half-life of the c-Myc protein. Thus, NNK-induced functional cooperation of Bcl2 and c-Myc in promoting cell survival and proliferation may occur in a novel mechanism involving their phosphorylation, which may lead to development of human lung cancer and/or chemoresistance.
authors.affiliation: University of Florida Shands Cancer Center, Department of Medicine, University of Florida, Gainesville, Florida 32610-0232, USA.
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Jin
authors.forename: Fengqin
authors.initials: F
authors.lastname: Gao
authors.forename: Tammy
authors.initials: T
authors.lastname: Flagg
authors.forename: Xingming
authors.initials: X
authors.lastname: Deng
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002038:Bungarotoxins / Q000494:pharmacology; D002273:Carcinogens / Q000494:pharmacology*; D018288:Carcinoma, Small Cell; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D008175:Lung Neoplasms; D008928:Mitochondria / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009602:Nitrosamines / Q000494:pharmacology*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D051571:Protein Kinase C-alpha; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering; D011978:Receptors, Nicotinic; D015398:Signal Transduction / Q000187:drug effects; D019311:Staurosporine / Q000494:pharmacology; D064569:alpha7 Nicotinic Acetylcholine Receptor
chemical_list: D000970:Antineoplastic Agents; D002038:Bungarotoxins; D002273:Carcinogens; C579167:Chrna7 protein, human; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009602:Nitrosamines; D019253:Proto-Oncogene Proteins c-bcl-2; D016271:Proto-Oncogene Proteins c-myc; D034741:RNA, Small Interfering; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; C016583:4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone; C496628:PRKCA protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019311:Staurosporine; D002945:Cisplatin; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one