Cucurbitacin B induces DNA damage and autophagy mediated by reactive oxygen species (ROS) in MCF-7 breast cancer cells

• DOI: 10.1007/s11418-015-0918-4
• Publication Date: 2015-05-27T14:47:05Z
• Authors: Guowen Ren; Tongye Sha; Jiajie Guo; Wenxue Li; Jinjian Lu; Xiuping Chen
• Keywords: Biological Products; 0303 health sciences; Breast Neoplasms; Triterpenes; 3. Good health; 03 medical and health sciences; Autophagy; MCF-7 Cells; Humans; Female; Phosphorylation; Reactive Oxygen Species; DNA Damage

Cucurbitacin B (Cuc B), a natural compound extracted from cucurbitaceous plants, demonstrated potent anticancer activities, while the underlying mechanisms remain unclear. We investigated the anticancer effect of Cuc B on MCF-7 breast cancer cells. Cuc B drastically decreased cell viability in a concentration-dependent manner. Cuc B treatment caused DNA damage, as shown by long tails in the comet assay and increased γH2AX protein expression. Immunofluorescence staining showed that Cuc B treatment induced nuclear γH2AX foci. Cuc B activated DNA damage pathways by phosphorylation of ATM/ATR [two large phosphatidylinositol-3-kinase-like kinase family (PIKKs) members]. Furthermore, it also induced autophagy, as evidenced by monodansylcadaverine (MDC) staining and autophagic protein expression. In addition, Cuc B treatment led to increased reactive oxygen species (ROS) formation, which was inhibited by N-acetyl-L-cysteine (NAC) pretreatment. NAC pretreatment inhibited Cuc-B-induced DNA damage and autophagy. Taken together, these results suggest that ROS-mediated Cuc-B-induced DNA damage and autophagy in MCF-7 cells, which provides new insights into the anticancer molecular mechanism of Cuc B.