Inhibition of Hec1 expression enhances the sensitivity of human ovarian cancer cells to paclitaxel

Abstract

Hec1, a member of the Ndc80 kinetochore complex, is highly expressed in cancers. The aim of this study was to explore the role and mechanism of action of Hec1 with respect to the cytotoxicity of paclitaxel in ovarian cancer. Thirty ovarian cancer samples and 6 normal ovarian samples were collected. Hec1 expression in these samples was determined with immunohistochemistry. Ovarian cancer cell lines A2780, OV2008, C13K, SKOV3, and CAOV3 and A2780/Taxol were examined. Cell apoptosis and cell cycle analysis were detected with flow cytometric technique. siRNA was used to delete Hec1 in the cells. The expression of related mRNAs and proteins was measured using RT-PCR and Western blot analysis, respectively. Hec1 expression was significantly higher in ovarian cancer samples than in normal ovarian samples, and was associated with paclitaxel-resistance and poor prognosis. Among the 6 ovarian cancer cell lines examined, Hec1 expression was highest in paclitaxel-resistant A2780/Taxol cells, and lowest in A2780 cells. Depleting Hec1 in A2780/Taxol cells with siRNA decreased the IC50 value of paclitaxel by more than 10-fold (from 590±26.7 to 45.6±19.4 nmol/L). Depleting Hec1 in A2780 cells had no significant effect on the paclitaxel sensitivity. In paclitaxel-treated A2780/Taxol cells, depleting Hec1 significantly increased the cleaved PARP and Bax protein levels, and decreased the Bcl-xL protein level. Hec1 overexpression is associated with the progression and poor prognosis of ovarian cancer. Inhibition of Hec1 expression can sensitize ovarian cancer cells to paclitaxel.