Abstract: Objective To explore the effect of olaparib on the survival, epithelial-mesenchymal transition ( EMT ) and tumor stem cell-like characteristics of ovarian cancer ES2cells. Methods Ovarian cancer ES2 cells were culturedin vitro, and they were divided into 5groups: control group, low-dose olaparib group, middle-dose olaparib group, high-dose olaparib group and doxorubicin 0. 5 μmol / L group. Cells proliferation, apoptosis, invasion and migration were detected by 5-ethynyl-2′-deoxyuridine ( EDU) staining, flow cytometry, Transwell assay, and wound healing assay, respectively. The epithelial-mesenchymal transition ( EMT) of cells was observed under light microscope, tumor stem cell-like characteristics were observed by tumor spheroid formation assay, and protein expression level was detected by Western blotting. Results Compared with those in the control group, the apoptosis rate of ES2 cells and the expression level of Ecadherin were significantly increased in the low-, middle-, high-dose olaparib group and doxorubicin 0. 5 μmol / L group ( P < 0. 05), the ratio of EDU staining positive cells, number of invasioncells per unit area, cell wound-healing rate, number of tumor spheroid, spheroid diameter, and the expression levels of nuclear antigen Ki67, Survivin, vascular endothelial growth factor(VEGF), N-cadherin, cluster of differentiation 44 (CD44) and aldehyde dehydrogenase 1 (ALDH1) were significantly decreased in the middle-and high-dose olaparib group and doxorubicin 0. 5μmol / L group (P< 0. 05). Conclusion Olaparib of over 30 mg / L can significantly inhibit proliferation, invasion, and migration of ovarian cancer ES2 cells, and promote their apoptosis, which may be through inhibition of Ki67 and regulation of EMT.

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