Research Of FTZ And Active Ingredient On The Functionand Mechanism In Insulin-resistant HepG2 Cells Via NF-κB Pathway

Background:Diabetes, hypertension and coronary heart disease, all result from a common origin, insulin resistance(IR), called the “Common Soil” Hypothesis. The Fu Fang Zhen Zhu Tiao Zhi formula(FTZ), a Chinese medicinal decoction, has been used to relieve hyperlipidemia, atherosclerosis and other symptoms associated with metabolic disorders. Our previous study has also found that FTZ plays a role in preventing insulin resistance in Hep G2 cells.The key herb in FTZ that has been used to relieve hyperlipidemia and atherosclerosis is GPF. OA is the main effective active ingredient of GPF and has been used to relieve liver injury and treat hepatitis and diabete.Objective:To research the effect of Fufang Zhenzhu Tiaozhi formula(FTZ) and Oleanolic acid(OA) in insulin-resistance Hep G2 cells induced by free fatty acid(FFA) via NF-κB-IRS1-GLUT4 pathway. In order to illustrate the mechanism of FTZ attenuated insulin resistance.Methods:To compare and evaluate the effect of FTZ, GPF and OA on insulin resistance, Hep G2 cells were induced with FFA to model insulin resistance and were treated with FTZ, GPF and OA. The glucose content was also measured. To study the mechanism of FTZ and OA on insulin resistance, Hep G2 cells were then induced with FFA, and the glucose content, the levels of tumor necrosis factor-α(TNF-α), interleukin-6(IL-6), protein expression of nuclear factor kappa B(NF-κB), insulin receptor substrate 1(IRS1) and glucose transporter 4(GLUT4) in cells treated with OA were measured by ELISA and western blot analysis. After using pyrrolidine dithiocarbamate(PDTC), IRS1 protein expression was measured after treatment with FTZ and OA.Results:Our results revealed that FTZ, GPF and OA decreased the glucose content in Hep G2 cells in vitro. FTZ and OA reduced the levels of TNF-α and IL-6 and up-regulated IRS1 and GLUT4 protein expression. Moreover, FTZ and OA also reduced NF-κB protein expression in insulin-resistant Hep G2 cells. After blocking NF-κB, the expression of IRS1 protein had no obvious changes when treated with FTZ and OA. Conclusions:FTZ and OA attenuated insulin resistance and decreased the levels of TNF-α and IL-6. Meanwhile, FTZ and OA decreased NF-κB protein expression and up-regulated IRS1 and GLUT4 protein expression. Therefore, regulating the IRS1-GLUT4 pathway via NF-κB was the underlying mechanism of the effects of FTZ and OA on insulin resistance.