PI3K Inhibitor LY294002 Combined With MTOR Specificity Inhibitor RAD001 Significantly Reduced Proliferation And Induced Apoptosis Of Different Breast Cancer Molecular Subtypes Through PI3K/Akt/mTOR Pathway In Vitro

Objective:In this study, by using LY294002 and RAD001, the specific inhibitors of PI3K and mTOR, to observe whether the anti-tumor effects on the proliferation, cycle distribution and apoptosis of combined inhibitors were a synergistic effect, and were differences between different molecular characteristics of human breast cancer cells alone and in combination in vitro.Methods:Routinely cultured MCF-7, SK-BR-3 and MDA-MB-231 cells in vitro. Logarithmic phase cells among each cells were selected and divided into the blank control group, LY294002 group, RAD001 group and the combination group. MTT assay and flow cytometry were used to detect the cell proliferation, cell cycle distribution and cell apoptosis of different groups. Results:(1) LY294002 and RAD001 could significantly inhibit the proliferations of MCF-7, SK-BR-3 and MDA-MB-231 cells with a dose-dependent manner respectively (P<0.05), and compared with other cells, MDA-MB-231 cells were more sensitive to both drugs (P<0.05). The anti-tumor effects were significantly increased in combination groups of different cells, and showed an additive effects. (2) MCF-7, SK-BR-3 and MDA-MB-231 cells could be arrest in G1 phase by IC50 of LY294002 and RAD001 respectively(P＜0.05), and the effects of combination groups were more significantly compared with monotherapy groups(P<0.05). However, no significant differences among different cells. (3) LY294002 and RAD001 could significantly increase the apoptosis rates of human MCF-7, SK-BR-3 and MDA-MB-231 cells alone (P<0.05), but there were no differences between different cells. When two inhibitors were combined, the apoptosis rates of the different cells were significantly increased compared with single drug, especially in MDA-MB-231 cell. The apoptosis rates of MCF-7, SK-BR-3 and MDA-MB-231 cells were 17.58%,44.28% and 52.67% respectively, and there were significantly different between different cell lines (P<0.05).Conclusion:Targeted therapy on P13K/Akt/mTOR pathway could significantly inhibit the proliferation of human breast cancer cell lines by inducing apoptosis and arresting cell cycle distribution. By using a combination of different inhibitors which were targeted on different related genes of this pathway such as PI3K and mTOR, the anti-tumor effects were more significant increasd compared with monotherapy, especially in MDA-MB-231 cell line which were negative with ER, PR and HER-2. It was important to provide new research ideas for individualized treatment and translational medicine of breast cancer.