Sareen Dhruv, Darjatmoko Soesiawati R, Albert Daniel M, Polans Arthur S
Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
Mol Pharmacol. 2007 Dec;72(6):1466-75. doi: 10.1124/mol.107.039040. Epub 2007 Sep 11.
Resveratrol (RES), a natural plant polyphenol, has gained interest as a nontoxic chemopreventive agent capable of inducing tumor cell death in a variety of cancer types. However, the early molecular mechanisms of RES-induced apoptosis are not well defined. Using the human breast cancer cell lines MDA-MB-231 and MCF-7, we demonstrate that RES is antiproliferative and induces apoptosis in a concentration- and time-dependent manner. Preceding apoptosis, RES instigates a rapid dissipation of mitochondrial membrane potential by directly targeting mitochondria. This is followed by release of cytochrome c and second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (Smac/DIABLO) into the cytoplasm and substantial increase in the activities of caspases-9 and -3 in MDA-MB-231 cells. In addition, live cell microscopy demonstrates that RES causes an early biphasic increase in the concentration of free intracellular calcium ([Ca2+]i), probably resulting from depletion of the endoplasmic reticulum stores in breast cancer cells. In caspase-3-deficient MCF-7 cells, apoptosis is mediated by the Ca2+-activated protease, calpain, leading to the degradation of plasma membrane Ca2+-ATPase isoform 1 and fodrin; the degradation is attenuated by buffering [Ca2+]i and blocked by calpain inhibitors. Mitochondrial permeability transition pore antagonists also blocked calpain activation. In vivo mouse xenograft studies demonstrate that RES treatment inhibits breast cancer growth with no systemic toxicities. Together, these results suggest a critical role for mitochondria not only in the intrinsic apoptotic pathway but also in the Ca2+ and calpain-dependent cell death initiated by RES. Thus, RES may prove useful as a nontoxic alternative for breast cancer treatment.
白藜芦醇（RES）是一种天然植物多酚，作为一种无毒的化学预防剂，能够诱导多种癌症类型的肿瘤细胞死亡，因而受到关注。然而，RES诱导细胞凋亡的早期分子机制尚未明确。我们使用人乳腺癌细胞系MDA-MB-231和MCF-7，证明RES具有抗增殖作用，并以浓度和时间依赖性方式诱导细胞凋亡。在细胞凋亡之前，RES通过直接靶向线粒体，促使线粒体膜电位迅速消散。随后，细胞色素c和第二线粒体衍生的半胱天冬酶激活剂/低pI凋亡直接抑制因子结合蛋白（Smac/DIABLO）释放到细胞质中，MDA-MB-231细胞中的半胱天冬酶-9和-3的活性大幅增加。此外，活细胞显微镜检查表明，RES导致细胞内游离钙（[Ca2+]i）浓度早期呈双相增加，这可能是由于乳腺癌细胞内质网储存耗竭所致。在缺乏半胱天冬酶-3的MCF-7细胞中，细胞凋亡由Ca2+激活的蛋白酶钙蛋白酶介导，导致质膜Ca2+-ATPase同工型1和血影蛋白降解；通过缓冲[Ca2+]i可减弱这种降解，钙蛋白酶抑制剂可阻断这种降解。线粒体通透性转换孔拮抗剂也可阻断钙蛋白酶激活。体内小鼠异种移植研究表明，RES治疗可抑制乳腺癌生长，且无全身毒性。总之，这些结果表明线粒体不仅在内在凋亡途径中起关键作用，而且在RES引发的Ca2+和钙蛋白酶依赖性细胞死亡中也起关键作用。因此，RES可能被证明是一种无毒的乳腺癌治疗替代药物。
