Abstract: Objective: To study the expression levels of forkhead transcription factor(FoxO1) mRNA and protein in the insulin resistance (IR) HepG2 cells model (HepG2/IR) and IR reversal HepG2 cells model (HepG2/IR-PH), and to explore its mechanism in IR.Methods: The HepG2/IR was induced with different doses of insulin (1×10^-10, 1×10^-9, 1×10^-8, 1×10^-7, 1×10^-6 and 1×10^-5 mol·L^-1) for different time(24, 36 and 48 h)in the HepG2 cells.The cells in control group were not treated with insulin. The glucose levels in supernant were determined by glucose oxidase method, and the glucose consumption in HepG2 in various groups were calculated to confirm the optimum induction conditions of HepG2/IR. The HepG2/IR-PH was induced with different doses of pioglitazone hydrochloride (PH) (0.156, 0.313, 0.625, 1.250, 2.500, 5.000, 10.000 and 20.000 mmol·L^-1) in the HepG2 cells, and control group was set up at the same time. The proliferation activities of cells were observed by MTT assay to confirm the optimum reversal concentration of PH. The FoxO1 mRNA and protein expression levels were detected by Real-time PCR and Western blotting methods.Results: The glucose consumption decreased by 45.84% in HepG2/IR after treated with 1×10^-7 mol·L^-1 insulin for 36 h, and there was significant difference compared with control group(P<0.05), the proliferation activity of cells had no change in the HepG2/IR-PH after treated with 1.25 mmol·L^-1 PH for 24 h(P>0.05).Compared with control group, the expression levels of FoxO1 mRNA and protein in HepG2/IR were significantly increased(P<0.01); compared with control group, the expression levels of FoxO1 mRNA and protein in HepG2/IR-PH had no significant differences(P>0.05).Conclusion: The IR of HepG2/IR is associated with the FoxO1 mRNA expression. The detection of FoxO1 mRNA seems to be an indicator to evaluate the efficacy of insulin sensitizer, and inhibiting the expression of FoxO1 mRNA may be developed as a potential therapy for type 2 diabetes.

Key words: insulin resistance, HepG2 cells, insulin resistance reversal, forkhead transcription factor