PKM2 aggravates palmitate-induced insulin resistance in HepG2 cells via STAT3 pathway

Studies have identified that PKM2 is related to the development of glucose intolerance and insulin resistance in rodents and humans. However, the underlying mechanism remains largely unknown. In the present study, we found that PKM2 expression was significantly elevated in insulin-resistant hepatic tissues and hepatocytes, implicating an association between PKM2 expression and hepatic insulin resistance (IR). In vitro study revealed that overexpression of PKM2 impaired the insulin signaling pathway by decreasing the phosphorylation of protein kinase B (Akt) and glycogen synthase kinase-3β (GSK3β). Furthermore, PKM2 overexpression enhanced the effects of PA on the lipid accumulation, the expression of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) and hepatic glucose uptake. Intriguingly, PA-induced insulin resistance was suppressed following by the ablation of PKM2 in HepG2 cells. We also found that STAT3 was significantly activated by PKM2 overexpression. Moreover, we identified that PKM2 could interact directly with STAT3. Taken together, these studies demonstrate that PKM2 may promote hepatic IR via STAT3 pathway and would provide a new insight into dissecting the molecular pathogenesis of hepatic insulin resistance.