Leptin Promotes The Proliferation,Invation And Migration Of Breast Cancer Cells By Up-Regulation Of ACAT2 Expression

Objective:To investigate the effect of leptin on the fatty acid metabolism enzymes and proliferation, invasion and migration of breast cancer cells. From the view of fatty acid metabolism, the pathogenesis of breast cancer was enriched, which could provide experimental evidences for the novel therapeutic target of breast cancer.Methods :1. WB and IF assay were applied to identify the expression of leptin receptors OB-Rb and OB-Rt in human breast cancer cells MCF-7, T47D. Leptin-induced proliferation of MCF-7 and T47D cells were determined by CCK8 assay; scratch assay and transwell assay were determined to investigate cells invasion and migration.2. Gene expression profile of fatty acid metabolism in MCF-7 cells treated with leptin was detected by QRT-PCR array, and ACAT2 gene was one of the candidates and was selected for the subsequent experiment. The ACAT2 mRNA or protein expression in MCF-7 and T47D cells was determined by QRT-PCR and western blot, respectively.3. Treated with specific inhibitor of ACAT2(Pyripyropene A, PPPA) in MCF-7 and T47D cells, the effects of leptin on proliferation, migration and invasion of MCF-7, T47D cells were detected. Western blot was employed to assess the effects of leptin on the expression of C-myc and Cylind1.4. With addition of Inhibitor of JAK/STAT3, MAPK/ERK and PI3K/Akt signaling pathways, we determined the protein expression of ACAT2 and SREBP2 induced by leptin in MCF-7 and T47D cells to investigate the potential mechanism of signaling pathways activated by leptin.Results:1. OB-Rb and OB-Rt were all presented in MCF-7 and T47D cells by Western blot and Immunofluorescence assay. Compared with control group, the proliferation of leptin-treated MCF-7 and T47D cells was increased significantly. Compared with the control group, the wound recovery rates and the number of cells were increased in scratch assay(p<0.05) and transwell assay(p<0.05) respectively, which indicated that leptin could promoted the invasion and metastasis of human breast cells MCF-7, T47D.2. QRT-PCR array results showed that leptin up-regulated the expression of ACAT2 significantly(p<0.05), and the results of QRT-PCR and WB showed that leptin also up-regulated ACAT2 mRNA and protein expression of MCF-7 and T47D cells in a dose and time-dependent manner.3. Inhibited by PPPA, ACAT2-specific inhibitor, the proliferation, migration and invasion induced by leptin were attenuated in MCF-7 and T47D cells. The protein expressions of C-myc and Cylind1 in PPPA-treated group were significant lower than that of control.4. The results showed that leptin-induced protein expression of ACAT2 and SREBP2 were abolished when PI3K/AKT signaling pathway was suppressed by inhibitor, whereas blockage of JAK/STAT3 and MAPK/ERK signaling pathways could not restore the protein of ACAT2 and SREBP2.Conclusion:1. Leptin could promote the proliferation,invasion and metastasis of human breast cells MCF-7, T47D,which might associated with the high expression of ACAT2 induecd by leptin.2. Activation of PI3K/Akt signaling pathway might result to up-regulation the expression of ACAT2 induced by leptin in MCF-7, T47D cells.