Metformin Exhibits Anticancer Effects Through AMPK-dependent Phosphorylation Of ABAT

Background:Breast cancer is the most common epitheliogenic malignant tumor in females,and one of the leading causes of morbidity and mortality for women.AMP-activated protein kinase(AMPK)is a cellular energy sensor.There are numerous epidemiological studies that have put forth evidence suggesting utility of metformin,a known pharmacological activators of AMPK,as an anti-cancer agent.But the mechanism remains unclear.Object:Our laboratory found nuclear translocation of ABAT can inhibit the proliferation and growth of breast cancer cell.And in previous experiments we confirmed that AMPK directly interacts with and phosphorylates ABAT.So we suspect that the antitumorigenic effects of metformin on breast cancer is related to nuclear translocation of ABAT.Methods:AMPK phosphorylation was analyzed by Western Blot.The effect of metformin on the proliferation of breast cancer cells was studied by cell counting and soft agar cloning assay.Immunofluorescence and nuclear-cytoplasmic separation experiments were used to detect ABAT nuclear entry.Effect of phosphorylation of ABAT on the proliferation of breast cancer cells inhibited by metformin was detected by soft agar assayResults:Metformin activated AMPK and inhibited growth and proliferation of breast cancer cells.We observed that metformin resulted in the nuclear translocation of ABAT in breast cancer cell using confocal microscopy and subcellular fractionation analysis.Compared with the control group,ABAT-T286A cells had weak inhibitory effects on the colony formation.Conclusions:Our results indicate that AMPK and ABAT play important roles in the impact of metformin on breast cancer.Phosphorylated at Thr286 by AMPK mediates ABAT nuclear entry.This study expands the mechanism of metformin as an anti-tumor drug,and has implications for fully understanding the antitumorigenic effect and mechanism of metformin in breast cancer.