Artemisinin induces selective and potent anticancer effects in drug resistant breast cancer cells by inducing cellular apoptosis and autophagy and G2/M cell cycle arrest.

PURPOSE: To investigate the anticancer properties of a well-known naturally occurring sesquiterpene lactone - artemisinin - against cisplatin resistant human breast carcinoma cells along with examining its effects on apoptosis, autophagy as well as cell cycle phase distribution.
METHODS: MTT assay was used to study cytotoxic effects of artemisinin while clonogenic assay analysed its effects on cancer cell colony formation. Fluorescence microscopy using DAPI staining was employed to study apoptotic effects of artemisinin which was followed by annexin V/propidium iodide (PI) assay which quantified the apoptotic effects of artemisinin in cancer cells. Apoptotic effects of artemisinin were finally confirmed by western blot assay by analysing its effects on Bcl-2 and Bax protein expressions. Effects of artemisinin on autophagy were determined by transmission electron microscopy (TEM). Effects on cell cycle were analysed by flow cytometry and western blot.
RESULTS: The results indicated that artemisinin led to considerable and dose-dependent antiproliferative effects on MDA-MB-231 cisplatin-resistant breast cancer cells with less toxicity in normal cell line, thus exhibiting selectivity. The colony formation decreased significantly as artemisinin dose increased. DAPI and comet assays revealed that artemisinin induced powerful apoptotic effects, triggering significant dose-dependent DNA damage. TEM indicated that artemisinin induced autophagy in MDA-MB-231 cisplatin-resistant human breast cancer cells by creating autophagosomes and autophagic vacuoles. The molecule also targeted G2/M phase cell cycle along with targeting some key cell cycle related proteins including cyclin-B1, cyclin D1 and cyclin E.
CONCLUSION: The results show that artemisinin showed strong anticancer effects in MDA-MB-231 cisplatin-resistant cancer cells by triggering apoptosis and autophagy and G2/M phase arrest.