Enhanced sensitivity of breast cancer MDA-MB-231 cells to chemotherapy by silencing forkhead box C2 gene with RNA interference technology

Abstract

Objective To observe the effects of forkhead box C2 gene (FOXC2) short hairpin RNA on docetaxel chemotherapy sensitivity of human breast cancer MDA-MB-231 cells.Methods MDA-MB-231 cells were transfected with recombinant expression plasmid FOXC2-small interfering RNA (siRNA) by lipofectamine 2000,and the expression of FOXC2 mRNA and protein was detected at 48 h after transfection.The morphological changes of apoptotic cells were observed under fluorescent microscope at 72 h after transfection.Methyl thiazol tetrazolium (MTT) assay was used to examine the inhibitory rate and the 50％ inhibitory concentration (IC50).Flow cytometry was applied to examine apoptosis and cell cycle at 72nd h after transfection.Results As compared with negative control plasmid and FOXC2-siRNA non-transfection group,the typical apoptotic morphology of MDA-MB-231 cells was observed,and the mRNA and protein expression levels of FOXC2 were obviously reduced in FOXC2-siRNA transfection group (P ＜ 0.05).Silencing FOXC2 increased sensitivity of MDA-MB-231 cells to docetaxel (P ＜ 0.05),and IC50 was decreased from (6.08 ±1.23) mg/L to (0.65 ±0.01) mg/L.Meanwhile,the apoptosis rate of MDA-MB-231 cells transfected with pFOXC2-shRNA was (20.01 ± 0.19)％,which was significantly higher than other three groups,and the proportion of cells in S phase and G0/G1 phase was decreased and that in G2/M phase was increased (P ＜0.05).Conclusion Down-regulation of FOXC2 expression by siRNA in breast cancer MDA-MB-231 cells could effectively induce apoptosis of MDA-MB-231 cells and increase their sensitivity to docetaxel. Key words: Breast cancer; Docetaxel; Apoptosis; Sensitizing effect