The inhibitory effects of andrographolide on malignant

• Main Authors: Po-Xuan Lee, 李柏萱
• Other Authors: Shu-Ling Fu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/92104572950940240795

碩士 === 國立陽明大學 === 傳統醫藥研究所 === 102 === Andrographolide is the main ingredient in the leaves of Andrographis paniculata. Currently, andrographolide is known to exhibit anti-cancer activity on various types of human cancers, including breast cancer and colon cancer. Breast cancer is most common type of cancer in women. Among different types of breast cancer, triple negative (ER-, HER2-, PR-) breast cancer is highly malignant and less responsive to conventional chemotherapy. Therefore, developing more effective treatment strategy is in great demand. On the other hand, Thoc1 is a component of the transcription/export complex (TREX), whose functions include assisting RNA pol II for transcription, RNA processing and nuclear export. The expression level of Thoc1 correlates with the proliferation and metastasis potential of human breast cancer cells, indicating that Thoc1 is a potential drug target. Currently, the effet of andrographolide on triple negative breast cancer cells and on Thoc1 expression level has never been explored. In this study, we investigate the cytotoxic effects of andrographolide and its derivatives on a triple negative breast cancer cell line MDA-MB-231 which has elevated Thoc1 expression. Furthermore, the molecular mechanisms underlying andrographolide-mediated cell death of MDA-MB-231 was also determined. The cytotoxicity of andrographolide on MDA-MB-231 was measured with MTT assays. We found that andrographolide effectively reduced the viability of MDA-MB-231 but had less toxic effect on human immortalized BJ-1 cells. In addition, andrographolide-mediated cell death occurred through both autophagy and apoptosis. Andrographolide promoted autophagy via increasing the formation of autophagosome marker, LC3-II. In addition, andrographolide also increased the activity of apoptotic enzyme Caspase-3. Suppression of andrographolide-induced autophagy in MDA-MB-231 cells with an autophagy inhibitor 3-MA attenuates the Caspase-3 activation. However, Treatment with an apoptosis inhibitor Z-VAD-FMK did not affect the andrographolide-induced LC3-II production. Notably, andrographolide could suppress Thoc1 expression in MDA-MB-231, and the expression level of Thoc1 reversely correlated with the production of autophagosome marker LC3-II. Moreover, compared with the control groups, both autophagic and apoptotic markers were affected in thoc1-knockdowned or thoc1-overexpressing cells. Nevertheless, the role of Thoc1 in andrographolide　-induced apoptosis remains to be further evaluated. The cytotoxic activity of several andrographolide analogs on MDA-MB-231 was also evaluated. Among them, NCTU-322 and Andro-NBD could reduce Thoc1 expression, induce autophagy and promote cell death at lower concentrations than andrographolide. Notably, both compounds at the effective concentrations did not cause significant cell death of human immortalized BJ-1 cells. In conclusion, andrographolide could decrease the viability of MDA-MB-231 through induction of autophagy and apoptosis. Andrographolide also decreases the expression of Thoc1, a known tumor-promoting protein in breast cancer. Together, this study demonstrates that andrographolide is a potential compound for the treatment of triple-negative human breast cancer.