Alcohol and PAH-induced carcinogenesis

描述(申请人提供)：流行病学研究表明，乙醇在一定条件下可能会起到致癌或促癌作用。有相当多的证据表明，与吸烟有关的酒精滥用增加了烟草烟雾的致癌潜力。酒精增强烟草烟雾致癌作用的机制尚不清楚。我们观察到，用(/-)-反苯并[a]芘-7，8-二醇-9，10-环氧化物[抗BPDE]处理促进敏感的JB6 Cl41细胞，[抗BPDE]是苯并[a]芘(烟草烟雾中存在的一种致癌多环芳烃)的最终致癌代谢产物，可诱导DNA合成抑制；细胞用生理浓度的乙醇预处理可解除BPDE诱导的DNA合成抑制。乙醇处理对BPDE-DNA加合物的形成没有任何影响，BPDE-DNA加合物可以引起细胞对BPDE的反应。此前，我们观察了BPDE处理JB6细胞后P53抑癌蛋白的积聚和G1-&GT；S细胞周期的停滞以及细胞转化。我们推测，乙醇增强多环芳烃致癌作用的机制之一包括通过p53依赖或非p53途径逆转DNA损伤诱导的细胞周期停滞和/或通过抑制细胞凋亡而增强细胞存活。我们的研究包括乙醇对BPDE诱导的(1)锚定非依赖性细胞生长(体外测量BPDE诱导的细胞转化的增强)和细胞周期的影响，(2)导致细胞周期停滞的P53反式激活功能(包括稳定/磷酸化和激活)，以及P53非依赖性(PI3-K/ERK/c-Jun/AP-1信号)细胞周期停滞和(3)细胞凋亡反应。我们的研究将包括使用促进剂敏感的小鼠表皮JB6细胞(广泛用于肿瘤促癌研究)和人类小气道上皮(SAE)细胞(用于烟草致癌研究的相关细胞系)的体外研究。该提案的总体目标是了解乙醇引起其与BPDE的共同遗传毒性效应，从而增强多环芳烃诱导致癌性的潜在机制。从这些研究中获得的数据将有助于评估在存在烟草烟雾成分的情况下酒精带来的相关健康风险，并将有助于制定预防癌症的治疗战略。

DESCRIPTION (provided by applicant): Epidemiological studies indicate that ethanol under certain conditions may function as co-carcinogen or tumor promoter. There is considerable evidence that alcohol abuse associated with smoking increases carcinogenic potential of tobacco smoke. The mechanism of potentiation of tobacco smoke-induced carcinogenicity by alcohol is not known. We observed that treatment of promotion sensitive JB6 Cl41 cells with (+/-)-anti- benzo[a]pyrene-7,8-diol-9,10-epoxide [anti-BPDE also called BPDE], an ultimate carcinogenic metabolite of benzopyrene (a carcinogenic PAH present in tobacco smoke) elicites DNA synthesis inhibition; and pre-treatment of cells with physiological concentration of ethanol relieves BPDE-induced DNA synthesis inhibition. Ethanol treatment does not have any effect on BPDE-DNA adduct formation which elicits cellular responses to BPDE. Previously we observed accumulation of p53 tumor suppressor protein and G1->S cell cycle arrest as well as cell transformation in response to BPDE treatment of JB6 cells. We hypothesize that one of the mechanisms of the potentiation of PAH-induced carcinogenicity by ethanol includes its ability to override DNA damage- induced cell cycle arrest via p53-dependent or p53-independent pathway and/or potentiation of cell survival through inhibition of apoptosis. Our studies in this proposal include examination of the effect of ethanol on BPDE-induced (1) anchorage- independent cell growth (in vitro measurement of potentiation of BPDE-induced cell transformation) and cell cycle profile, (2) p53 transactivating function (including stability/phosphorylation and activation) which leads to cell cycle arrest, as well as p53- independent (PI3-K/ ERK/c-Jun/AP-1 signaling) cell cycle arrest and (3) apoptosis response. Our studies will include in vitro study using promotion-sensitive mouse epidermal JB6 cells (widely used for tumor promotion studies) and human small airway epithelial (SAE) cells (relevant cell line for the study of tobacco smoke carcinogenesis). The overall objective of the proposal is to understand the underlying mechanism by which ethanol elicits its co-genotoxic effect with BPDE and thereby enhances PAH- induced carcinogenicity. Data obtained from these studies will help assessing the associated health risk presented by alcohol in presence of tobacco smoke constituents and will be useful to develop therapeutic strategies in the prevention of cancer.