The Influence Of Downregulating The Expression Of Med19 Gene On Drug Sensitivity To Paclitaxel In Breast Cancer Cells With Different P53 Genetic Background

Objective: To investigate the influence of downregulating the expression of Med19 gene on drug sensitivity to paclitaxel in breast cancer cells with different P53 genetic background.Methods: The two breast cancer cells of MCF-7(P53 wild-type) and MDA-MB- 231(P53 mutation type) cells were employed as the research object. Med19 RNAi lentiviral infected the breast cancer cells of different P53 genetic background(Knock-down group, KD group), and set non-infected(CON) group, empty sensor-infected(NC) group. The efficiency of infection was observed by inverted fluorescence microscope. The expression levels of Med19, P53, p P53 and P21 protein were detected by Western Blot. To observe the influence of downregulating the expression of Med19 gene on drug sensitivity to paclitaxel in breast cancer cells, the cell proliferation assays were performed to detect the cancer cell proliferation inhibition rate by different doses of paclitaxel before and after knocking-down Med19 gene,and Flow Cytometry was employed to observe the cell cycle and cell apoptosis.Results: The protein expression levels of Med19 in MCF-7 and MDA-MB-231 cells in KD group were significantly lower than that in CON group and NC group(p<0.05).The P53, p P53,P21 protein appeared significantly upregulated in the KD group of MCF-7 cells(p<0.05). But the MDA-MB-231 cells had no significant difference between each groups(p>0.05). The results of the MTT showed that paclitaxel caused a concentration-dependent inhibition on the MCF-7 and MDA-MB-231 cellular proliferation inhibition in(0.01~50)μg/ml range, there were significant difference between each concentration groups(p<0.05). The inhibition rate of MCF-7 cells in paclitaxel + KD group significantly up regulated than those in CON group and paclitaxel+NC group(p<0.05), but not in the MDA-MB-231cells(p>0.05). The apoptosis rate of KD group in MCF-7 cells(59.77±2.31)% was significantly higher than that in NC group(36.42±4.27)%,which shows the fact that knock-down Med19 gene increase the apoptosis rate of MCF-7 cells by paclitaxel. But there were no statistically significant difference between group in MDA-MB-231cells(p>0.05), even if the apoptosis rate in paclitaxel+KD group(40.07±2.21)%was slightly higher than that in paclitaxel+NC group(35.42±4.16)%(p>0.05). The consequence of cell cycle indicated that MCF-7 cells and MDA-MB-231 cells appeared G2/M block phenomenon by paclitaxel. Interestingly, knock-down of Med19 augments the proportion of G0/G1 phase in MCF-7 cells paclitaxel+KD group [(10.12±0.95)%](p<0.05) but not in MDA-MB-231 cells paclitaxel+KD group.Conclusion: MCF-7cells are enhanced the paclitaxel chemotherapy sensitivity by knock-down Med19 gene, and the mechanism may be enhance P53 and P21 gene excitation and promote cell apoptosis.