Arsenic Trioxide Inhibits Cell Growth And Invasion Through Down-regulation Of MiR-27a Expression In Breast Cancer Cells

Background and Objective: Breast cancer is a common malignancy which is dangerous to women’s health,and shows an increasing incidence and younger trend. In recent years, the researchers found that arsenic trioxide has significant anti-tumor effect on a variety of tumors, Although arsenic trioxide has received extensive attention as a new cancer treatment agent, the specific molecular mechanism of arsenic trioxide-mediated anti-tumor activity remains elusive. Therefore, in-depth investigation of the molecular insight and discovery of experimental evidence for clinical use of arsenic trioxide are necessary. The purposes of this research: 1. To determine the effects of arsenic trioxide on human breast cancer cells(MDA-MB-231, SK-BR-3, MCF-7)growth, migration, invasion and apoptosis. 2. To explore whether arsenic trioxide could down-regulate mi R-27 a expression, leading to inhibition of cell growth, migration,invasion and induction of apoptosis in breast cancer cells, and thus exerting its anti-tumor functions.Methods: 1. We investigated the effect of arsenic trioxide on cell growth, migration,invasion and apoptosis by MTT assay, wound-healing assay, matrigel invasion assay and Flow Cytometry(FCM), respectively, in MDA-MB-231, SK-BR-3, MCF-7 cell lines. 2. mi R-27 a expression was examined by RT-PCR assay. 3. Using the transient transfection of mi R-27 a inhibitor to down-regulate mi R-27 a in breast cancer cells and combine with arsenic trioxide treated cells, we observe the changes of cell growth,migration and apoptosis. Western blot analysis was used to determine the expression of FBW7 and FOXO1 proteins.Results: 1. Arsenic trioxide inhibited breast cancer cell growth. With increasing concentrations of arsenic trioxide its inhibition of breast cancer cells(MDA-MB-231,SK-BR-3, MCF-7) growth gradually increased and showed a dose-dependent manner.IC50 values for arsenic trioxide treatment in MDA-MB-231 and MCF-7 were about 10 μM and in SK-BR-3 was about 8 μM by MTT assay. We used 10 μM to explore the role of arsenic trioxide in these three breast cancer cells.2. Arsenic trioxide inhibited the cell migration and invasion and promoted apoptosis in breast cancer cells. Compared with the control group, breast cancer cells treated with 8 μM and 10 μM Arsenic trioxide for 48 hours, showed a markedly reduced migration and invasion, but apoptosis was significantly increased in a dose-dependent manner(P<0.05).3. Arsenic trioxide down-regulated the expression of mi R-27 a in breast cancer cells.Arsenic trioxide significantly decreased the expression of mi R-27 a in breast cancer cells after 10 μM Arsenic trioxide treatment for 48 hours(P<0.05).4. Arsenic trioxide inhibited breast cancer cell proliferation, migration, invasion capacity, and promoted apoptosis by down-regulating the expression of mi R-27 a. We used arsenic trioxide and lipo2000-mediated transient transfection of mi R-27 a inhibitor inhibited the expression of mi R-27 a in breast cancer cells. The results showed that both arsenic trioxide treatment and the transient transfection of mi R-27 a inhibitor inhibited breast cancer cell growth, migration, invasion capacity, and promoted apoptosis, and the combination treatments showed more significant effects(P<0.05).5. Arsenic trioxide and mi R-27 a inhibitor up-regulated the expression of FOXO1 and Fbw7 protein in breast cancer cells and down-regulated the expression of Cyclin E protein, and when the combination treatments showed more significant effects.Conclusions: 1. Arsenic trioxide down-regulated mi R-27 a expression in breast cancer and then inhibited cell growth, migration and invasion, and induced apoptosis.2. Arsenic trioxide up-regulated Fbw7 and FOXO1 protein expressions,down-regulated Cyclin E protein expression in MDA-MB-231,SK-BR-3, and MCF-7cells.