减肥药奥利司他(XenicalTM)在乳腺癌细胞中的抗肿瘤作用:阻断细胞周期进程，促进凋亡细胞死亡和pea3介导的Her2/neu (erbB-2)癌基因转录抑制
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梅内德斯，李伟龙，卢普
减肥药奥利司他(XenicalTM)在乳腺癌细胞中的抗肿瘤作用:阻断细胞周期进程，促进凋亡细胞死亡和pea3介导的Her2/neu (erbB-2)癌基因转录抑制
安·昂科尔。2005年8月;16(8):1253-67。Epub 2005 5月3日。
- PubMed ID
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15870086 (PubMed视图］
- 摘要
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背景:美国食品和药物管理局(FDA)批准的减肥药奥利司他(xenicalmark)最近被证明具有抗前列腺癌细胞的抗肿瘤特性，因为它能够阻断脂肪酸合成酶(FAS)的成脂活性。FAS(致癌抗原-519)在约50%的乳腺癌中上调，是预后不良的一个指标，最近已与Her2/neu (erbB-2)癌基因功能相关。材料和方法:我们评估了奥利司他对人乳腺癌细胞系SK-Br3的抗肿瘤作用，这是乳腺癌中FAS和Her2/neu过表达的体外范例。结果:细胞周期分析显示，微摩尔浓度的奥利司他以时间和剂量依赖的方式诱导细胞群分布的显著变化，包括G2-M期的完全丧失，s期的积累和伴随出现的亚g1(凋亡)细胞的增加。Poly (adp -核糖)聚合酶(PARP)裂解是细胞凋亡所需的早期事件，在奥利司他处理的G1期细胞中更为明显。当我们在奥利司他诱导的FAS活性抑制和乳腺癌细胞增殖抑制之后表征参与细胞事件的信号分子时，在奥利司他处理的SK-Br3细胞中发现了Her2/neu编码的p185(Her2/neu)癌蛋白的显著下调(>减少90%)。有趣的是，在奥利司他处理的SK-Br3细胞中观察到dna结合蛋白PEA3的显著积累，PEA3是Ets转录因子家族的成员，专门针对Her2/neu基因启动子上的PEA3结合motif，并下调其活性。当在SK-Br3细胞中瞬时转染由Her2/neu启动子驱动的荧光素酶报告基因时，发现奥利司他暴露显著抑制了Her2/neu基因启动子的活性，而带有突变结合DNA序列的Her2/neu启动子不受奥利司他的负调控，这表明奥利司他诱导的Her2/neu启动子上完整的PEA3结合位点是转录抑制Her2/neu过表达所必需的。RNA干扰(RNAi)介导的FAS基因表达沉默同样以pea3依赖的方式抑制了Her2/neu基因的表达，因此排除了非FAS奥利司他介导的作用。当奥利司他与抗her2 /neu抗体曲妥珠单抗(赫赛汀标记)同时使用(奥利司他+曲妥珠单抗)或连续使用(奥利司他—>曲妥珠单抗; trastuzumab --> orlistat) schedules was tested for synergism, addition or antagonism using the combination index (CI) method of Chou-Talalay, co-exposure of orlistat and trastuzumab demonstrated strong synergistic effects (CI10-90 = 0.110-0.847), whereas sequential exposure to orlistat followed by trastuzumab (CI10-90 = 0.380-1.210) and trastuzumab followed by orlistat (CI10-90 = 0.605-1.278) mainly showed additive or antagonistic interactions. Indeed, orlistat-induced FAS inhibition synergistically promoted apoptotic cell death when concurrently combined with trastuzumab as determined by an ELISA for histone-associated DNA fragments. Importantly, the degree of FAS expression in a panel of human breast cancer cell lines was predictive of sensitivity to orlistat-induced anti-proliferative effects as determined by a MTT-based characterization of metabolically viable breast cancer cells. Moreover, hypersensitivity to orlistat-induced cytotoxicity was observed in MCF-7 breast cancer cells engineered to overexpress Her2/neu (MCF-7/Her2-18 cells), which exhibit a significant up-regulation of FAS expression and activity. CONCLUSIONS: These findings reveal that the development of more potent and/or bioavailable orlistat's variants targeting the lipogenic activity of FAS may open a novel therapeutic avenue for treating Her2/neu-overexpressing breast carcinomas.