Katdare M, Osborne M P, Telang N T
Division of Carcinogenesis and Prevention, Strang Cancer Research Laboratory, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Oncol Rep. 1998 Mar-Apr;5(2):311-5. doi: 10.3892/or.5.2.311.
Aberrant proliferation and modulated apoptosis leading to impaired cellular homeostasis represent crucial early events in the multi-step carcinogenic process. Regulation of these perturbed biomarkers may predict efficacious prevention of cancer development. Present experiments on non-cancerous human mammary epithelial 184-B5 cells were designed to examine whether i) exposure to suspect environmental human carcinogen Benzo (a) pyrene (BP) alters the status of cell proliferation and apoptosis and ii) BP-induced alterations are modulated in response to select natural phytochemicals that inhibit rodent mammary tumorigenesis. Flow cytometric analysis, cellular immunoreactivity to proliferation specific and apoptosis specific gene products and anchorage-dependent colony formation represented quantitative endpoints. Cruciferous glucosinolate indole-3-carbinol (I3C), tea polyphenol (-) epigallo catechin gallate (EGCC) and soy isoflavone genistein (GEN) represented the chemopreventive test compounds. A single 24 h exposure to 39 lM BP resulted in a 50% decrease (P=0.02) in the ratio of quiescent (Q=G0) to proliferative (P=S + M) population in part due to increase in aberrantly proliferative cells. The BP-initiated cells also exhibited an 87.8% inhibition (P=0. 0001) in confluency-associated apoptosis and a concomitant decrease in cellular immunoreactivity to wild-type p53. Simultaneous treatment of cultures with BP + I3C, BP + EGCG and BP + GEN resulted in a 1.8- to 3.4-fold increase (P<0.01) in Q/P ratio and 1.8- to 6. 9-fold increase (P=0.001) in sub G0 (apoptotic) population. The induction of apoptosis was accompanied by enhanced p53 immunoreactivity (P<0.01). In long-term (21 day) experiments, BP treatment induced a 145.3% increase (P=0.001) in anchorage-dependent colony formation. This aberrant proliferation was inhibited by 44.2% to 65.3% (P=0.01) in the presence of the three phytochemicals. Thus, BP-induced aberrant proliferation is inhibited by the natural phytochemicals in part due to regulation of cell cycle progression and induction of p53 dependent apoptosis.
异常增殖和凋亡调控导致细胞内稳态受损，是多步骤致癌过程中的关键早期事件。对这些受干扰生物标志物的调控可能预示着对癌症发展的有效预防。目前针对非癌性人乳腺上皮184 - B5细胞进行的实验旨在检验：i）暴露于可疑环境人类致癌物苯并（a）芘（BP）是否会改变细胞增殖和凋亡状态；ii）BP诱导的改变是否会因选择抑制啮齿动物乳腺肿瘤发生的天然植物化学物质而受到调节。流式细胞术分析、细胞对增殖特异性和凋亡特异性基因产物的免疫反应性以及锚定依赖性集落形成代表了定量终点。十字花科硫代葡萄糖苷吲哚 - 3 - 甲醇（I3C）、茶多酚（-）表没食子儿茶素没食子酸酯（EGCG）和大豆异黄酮染料木黄酮（GEN）代表化学预防测试化合物。单次24小时暴露于39μM BP导致静止（Q = G0）与增殖（P = S + M）群体比例下降50%（P = 0.02），部分原因是异常增殖细胞增加。BP起始的细胞在汇合相关凋亡方面也表现出87.8%的抑制（P = 0.0001），同时对野生型p53的细胞免疫反应性降低。用BP + I3C、BP + EGCG和BP + GEN同时处理培养物导致Q/P比值增加1.8至3.4倍（P < 0.01），亚G0（凋亡）群体增加1.8至6.9倍（P = 0.001）。凋亡的诱导伴随着p53免疫反应性增强（P < 0.01）。在长期（21天）实验中，BP处理导致锚定依赖性集落形成增加145.3%（P = 0.001）。在三种植物化学物质存在的情况下，这种异常增殖受到44.2%至65.3%的抑制（P = 0.01）。因此，天然植物化学物质部分通过调节细胞周期进程和诱导p53依赖性凋亡来抑制BP诱导的异常增殖。
