Zheng Nan, Liu Lu, Liu Weiwei, Zhang Ping, Huang Huai, Zang Linghe, Hayashi Toshihiko, Tashiro Shin-ichi, Onodera Satoshi, Xia Mingyu, Ikejima Takashi
China-Japan Research Institute of Medical and Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang 110016, China.
Institute for Clinical and Biomedical Sciences, Kyoto 603-8072, Japan.
Arch Biochem Biophys. 2016 Feb 1;591:141-9. doi: 10.1016/j.abb.2016.01.002. Epub 2016 Jan 6.
We previously reported that silibinin induced a loss of cell viability in breast cancer (MCF-7) cells by ERα down-regulation. But whether this cytotoxicity depends on another estrogen receptor, ERβ, has yet to be elucidated. Therefore, we sought to explore the effects of ERβ modulation on cell viability by using an ERβ-selective agonist (Diarylprepionitrile, DPN) and an antagonist (PHTPP). Our data demonstrated that ERβ served as a growth suppressor in MCF-7 cells, and the incubation of silibinin, elevated ERβ expression, resulting in the tumor growth inhibition. The cytotoxic effect of silibinin was diminished by PHTPP and enhanced by DPN. Silencing of ERβ by siRNA confirmed these results. Apoptotic cascades, including the sequential activation of caspase-9 and -6, and finally the cleavage of caspase substrates, PARP and ICAD, caused by treatment with silibinin, were all repressed by PHTPP pre-treatment but exacerbated by DPN. Unlike ERα, ERβ did not involve autophagic process in the regulation, since neither autophagic inhibitor (3-MA) nor the inducer (rapamycin) affected the cell survival rates regardless ERβ activity. Taken together, silibinin induced apoptosis through mitochondrial pathway by up-regulating ERβ pathways in MCF-7 cells without the involvement of autophagy.
我们之前报道过，水飞蓟宾通过下调雌激素受体α（ERα）诱导乳腺癌（MCF-7）细胞丧失细胞活力。但这种细胞毒性是否依赖于另一种雌激素受体——雌激素受体β（ERβ），仍有待阐明。因此，我们试图通过使用ERβ选择性激动剂（二芳基丙腈，DPN）和拮抗剂（PHTPP）来探究ERβ调节对细胞活力的影响。我们的数据表明，ERβ在MCF-7细胞中起到生长抑制作用，水飞蓟宾孵育后，ERβ表达升高，导致肿瘤生长受到抑制。PHTPP可减弱水飞蓟宾的细胞毒性，而DPN则增强其细胞毒性。通过小干扰RNA（siRNA）沉默ERβ证实了这些结果。水飞蓟宾处理引发的凋亡级联反应，包括半胱天冬酶-9和-6的顺序激活，以及最终半胱天冬酶底物聚（ADP-核糖）聚合酶（PARP）和抑制凋亡CAD核酸酶（ICAD）的裂解，均被PHTPP预处理抑制，但被DPN加剧。与ERα不同，ERβ在调节过程中不涉及自噬过程，因为无论ERβ活性如何，自噬抑制剂（3-甲基腺嘌呤，3-MA）和诱导剂（雷帕霉素）均不影响细胞存活率。综上所述，水飞蓟宾通过上调MCF-7细胞中的ERβ途径，通过线粒体途径诱导凋亡，而不涉及自噬。
