Tsai Sun-Lung, Suk Fat-Moon, Wang Chun-I, Liu Der-Zen, Hou Wen-Chi, Lin Pei-Jung, Hung Ling-Fang, Liang Yu-Chih
Liver Research Unit, Department of Medical Research, Chi-Mei Medical Center, Yung-Kang City, Tainan, Taiwan.
Biochem Pharmacol. 2007 Dec 3;74(11):1575-86. doi: 10.1016/j.bcp.2007.08.009. Epub 2007 Aug 11.
Chemotherapeutic drugs are usually designed to induce cancer cell death via cell cycle arrest and/or apoptosis pathways. In this study, we used the chemical drug 15,16-dihydrotanshinone I (DHTS) to inhibit breast cancer cell proliferation and tumor growth, and investigate the underlying molecular mechanisms. Human breast cancer cell lines MCF-7 and MDA-MB-231 were both used in this study, and DHTS was found to significantly decrease cell proliferation by a dose-dependent manner in both cells. Flow cytometry indicated that DHTS induced G1 phase arrest in synchronous MCF-7 and MDA-MB-231 cells. When analyzing the expression of cell cycle-related proteins, we found that DHTS reduced cyclin D1, cyclin D3, cyclin E, and CDK4 expression, and increased CDK inhibitor p27 expression in a dose-dependent manner. In addition, DHTS inhibited the kinase activities of CDK2 and CDK4 by an immunocomplex kinase assay. In addition, DHTS also induced apoptosis in both cells through mainly mitochondrial apoptosis pathways. We found that DHTS decreased the anti-apoptotic protein Bcl-xL level and increased the loss of mitochondria membrane potential and the amount of cytochrome c released. Moreover, DHTS activated caspase-9, caspase-3, and caspase-7 and caused cell apoptosis. The fact that DHTS-induced apoptosis could be blocked by pretreating cells with pan-caspase inhibitor confirmed that it is mediated through activation of the caspase-3-dependent pathway. In a nude mice xenograft experiment, DHTS significantly inhibited the tumor growth of MDA-MB-231 cells. Taken together, these results suggest that DHTS can inhibit human breast cancer cell proliferation and tumor growth, and might have potential chemotherapeutic applications.
化疗药物通常旨在通过细胞周期阻滞和/或凋亡途径诱导癌细胞死亡。在本研究中，我们使用化学药物15,16-二氢丹参酮I（DHTS）来抑制乳腺癌细胞增殖和肿瘤生长，并研究其潜在的分子机制。本研究使用了人乳腺癌细胞系MCF-7和MDA-MB-231，发现DHTS在这两种细胞中均以剂量依赖性方式显著降低细胞增殖。流式细胞术表明，DHTS诱导同步化的MCF-7和MDA-MB-231细胞发生G1期阻滞。在分析细胞周期相关蛋白的表达时，我们发现DHTS以剂量依赖性方式降低细胞周期蛋白D1、细胞周期蛋白D3、细胞周期蛋白E和CDK4的表达，并增加CDK抑制剂p27的表达。此外，通过免疫复合物激酶测定，DHTS抑制了CDK2和CDK4的激酶活性。此外，DHTS还主要通过线粒体凋亡途径诱导这两种细胞凋亡。我们发现DHTS降低了抗凋亡蛋白Bcl-xL的水平，增加了线粒体膜电位的丧失和细胞色素c的释放量。此外，DHTS激活了caspase-9、caspase-3和caspase-7并导致细胞凋亡。用泛caspase抑制剂预处理细胞可阻断DHTS诱导的凋亡，这一事实证实其是通过激活caspase-3依赖性途径介导的。在裸鼠异种移植实验中，DHTS显著抑制了MDA-MB-231细胞的肿瘤生长。综上所述，这些结果表明DHTS可以抑制人乳腺癌细胞增殖和肿瘤生长，可能具有潜在的化疗应用价值。
