Autophagy is Involved in Anticancer Effects of Cucurbitacin E on Human Breast Cancer Cell Bcap-37

Objective To explore the effect of Cucurbitacin E (CuE) or CuE combined with autophagy inhibitor, Chloroquine (CQ) on the proliferation of human breast cancer cells Bcap-37 and its possible mechanism.

Methods MTT assay was used to measure the effect of CuE or CuE combined with CQ on Bcap-37 proliferation. The apoptosis was measured by flow cytometry. Western blot was used to detect LC3-Ⅰ/Ⅱand P62 protein expression. The autolysosome was observed by electronic microscopy.

Results CuE significantly inhibited the in vitro growth of human breast cancer cells by inducing the apoptosis. After treated with CuE, the expression of autophagy-related protein LC3-Ⅱ was increased, while LC3-Ⅰ, P62 expression were decreased. In addition, CuE also induced the formation of autolysosomes, indicating the activation of autophagy.

Conclusion CuE could induc the apoptosis of human breast cancer cells and cytoprotective autophagy. The inhibition of autophagy could significantly enhance the cytotoxicity of CuE to Bcap-37.