Abstract: Abstract:Objective To analyse the effects of high insulin on the expression and function of P-glycoprotein (P-gp), and preliminarily investigate the influence of insulin on chemotherapeutic sensitivity in MCF- 7/ADR cells. Methods MCF-7/ADR cells were cultured with different concentrations of insulin（0.001, 0.005, 0.01, 0.05 and 0.1 μmol/L). Real time PCR was used to detect the expression of P-gp mRNA. Western blot assay was used to detect the expression level of P gp. Rhodamine 123 was used to detect the efflux function level of P-gp. Cell viability and chemotherapeutic sensitivity were detected by MTT assay. Results High concentration of insulin (0.1 μmol/L) promoted the proliferation of MCF- 7/ADR cells. The concentration of insulin (0.05 and 0.1 μmol/L) accelerated P- gp mRNA and protein expression, which also augmented the efflux function of P-glycoprotein and reduced the chemotherapeutic sensitivity to epirubicin. Conclusion High concentration of insulin may influence the drug resistance of breast cancer cells by promoting the expression and function of P-glycoprotein of MCF-7/ADR cells.

Key words: insulin, P-glycoprotein;, drug resistance, neoplasm, Epirubicin, MCF-7/ADR cell