Summary: | 碩士 === 中國醫藥大學 === 藥學系碩士班 === 100 === 4β-Hydroxywithanolide E, an active component from Physalis peruviana, was found to have anti-breast cancer cytotoxicity, but the mechanism still need to be further discovered. In this study, we found that 4β-hydroxywithanolide E-induced human breast cancer MCF-7 cell apoptosis is irreversible and the caspase-9 pathway is involved in the 4β-hydroxywithanolide E-induced cell death. We also investigated the role of oxidative stress in 4β-hydroxywithanolide E-induced MCF-7 cell apoptosis. Exposure of MCF-7 cells to 4β-hydroxywithanolide E caused production of reactive oxygen species and a significant increase in antioxidative enzymes activity, such as superoxide dismutase (SOD) and catalase. Glutathione or N-acetylcysteine significantly inhibited the 4β-hydroxywithanolide E-triggered activity of the radical-scavenging enzymes and cell death. The 4β-hydroxywithanolide E-induced cell cycle arrest at G0/G1- and S-phase, changes in cell cycle regulators expression and microtubule distribution were reversed by pretreatment with glutathione or N-acetylcysteine in MCF-7 cells. In addition, glutathione or N-acetylcysteine selectively inhibited the 4β-hydroxywithanolide E-induced DNA damage and changes in the protein expression of DNA damage sensors and repair enzymes such as ATM (S1981), ??-H2AX, 53BP1, BRCA1, chk2 and XRCC4 in MCF-7 cells. We also found that MAP kinase, ubiquitin-conjugated protein degradation and cAMP pathways were not important determinants of apoptotic death induced by 4β-hydroxywithanolide E in MCF-7 cells.
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