Recent evidence shows that raddeanin A (RA), an oleanane-type triterpenoid saponin extracted from Anemone raddeana Regel, exerts remarkable cytotoxicity against cancer cells in vitro and in vivo. In addition, RA has also been found to activate autophagy in human gastric cancer cells. In this study, we investigated the molecular mechanisms underlying RA-induced autophagy as well as the relationship between RA-induced autophagy and its cytotoxicity in human breast cancer cells in vitro. Treatment with RA (2-8 μmol/L) dose-dependently enhanced autophagy, as evidenced by increased LC3 levels in breast cancer cell lines T47D, MCF-7 and MDA-MB-231. Furthermore, the Akt-mTOR-eEF-2K signaling pathway was demonstrated to be involved in RA-induced activation of autophagy in the 3 breast cancer cell lines. Treatment with RA (2-10 μmol/L) dose-dependently induced apoptosis in the 3 breast cancer cell lines. Pretreatment with the autophagy inhibitor chloroquine (CQ, 20 μmol/L) significantly enhanced RA-caused cytotoxicity via promoting apoptosis. In conclusion, our results suggest that modulating autophagy can reinforce the cytotoxicity of RA against human breast cancer cells.

中文翻译：

---

抑制eEF-2K介导的自噬增强了raddeanin A在体外对人乳腺癌细胞的细胞毒性。

最近的证据表明，从海葵raddeana Regel提取的齐墩果烷型三萜皂苷raddeanin A（RA）在体内和体外对癌细胞均具有显着的细胞毒性。另外，还发现RA可激活人胃癌细胞中的自噬。在这项研究中，我们调查了RA诱导的自噬的分子机制，以及RA诱导的自噬与其在人乳腺癌细胞中的细胞毒性之间的关系。RA（2-8μmol/ L）剂量依赖性增强自噬作用，乳腺癌T47D，MCF-7和MDA-MB-231细胞株中LC3水平升高证明了这一点。此外，Akt-mTOR-eEF-2K信号通路被证明与3种乳腺癌细胞系中RA诱导的自噬激活有关。RA（2-10μmol/ L）处理可剂量依赖性地诱导3种乳腺癌细胞株的凋亡。自噬抑制剂氯喹（CQ，20μmol/ L）预处理通过促进细胞凋亡显着增强了RA引起的细胞毒性。总之，我们的结果表明，调节自噬可以增强RA对人乳腺癌细胞的细胞毒性。