Apoptosis and Cell Cycle Arrest in Acute Myeloid Leukemia (AML) Induced by Metformin through Inhibition of the PI3K/AKT/mTOR Pathway

Background: In order to find cost-effective drugs for synergistic therapy to improve the survival rate of acute myeloid leukemia (AML) patients. The aim of this study was to explore the action and mechanism of action of metformin in acute myeloid leukemia (AML), on the hope of finding cost-effective drugs for synergistic therapy to improve the survival of acute myeloid leukemia (AML) patients.Methods: Human AML cell lines (HL-60 (Human Promyelocytic Leukemia Cells), Kasumi-1, and KG-1 (Acute myeloid leukemia)) were treated with different concentrations of metformin from 0 to 40 mM. Cell viability was determined using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide) assay, and cell cycle was assessed using flow cytometry. Hoechst 33258 and Annexin V-FITC/PI (Annexin V Fluorescein Isothiocyanate/Propidium iodide) double labeling were used to evaluate apoptosis, and western blotting was used to determine the expression levels of proteins related to cell cycle arrest, apoptosis, and signaling pathways. The MTT assay was used to determine cell viability.Results: Metformin at different concentrations could inhibit the proliferation of AML cells and primary cells. AML cells in G1 phase were significantly upregulated after metformin treatment. Hochest33258 staining and Annexin V-FITC/PI staining showed that metformin significantly induced apoptosis in AML cells. Western blot showed that metformin could activate caspase-3, caspase-9, poly ADP (Adenosine 5-diphosphoribose)-ribose polymerase 1 (PARP-1) and Bak, down-regulate the expression of myeloid cell leukemia-1 (Mcl-1), inhibite the expression of insulin-like growth factors 1R (IGF-1R) and phosphoinositide 3-kinase (PI3K), and ultimately inhibite the phosphorylation of protein kinase B (AKT) and mammalian target of rapamycin (mTOR).Conclusions: This study verified that metformin inhibits AML cell proliferation, induces apoptosis and G0/G1 cell cycle arrest by inhibiting the PI3K/AKT/mTOR pathway.