Effect of Candesartan Cilexetil as a Sensitive and Effective Inhibitor of SHP-1 on Insulin Signaling Pathway

The protein tyrosine phosphatases(PTPs) comprise a family of enzymes that specifically dephosphorylate tyrosyl residues. Among them, SHP-1 has been regarded as one of the best validated intracellular tyrosine phosphatases. Downregulation of SHP-1 has shown remarkable efficacy in improving insulin sensitivity in vivo in insulin signaling pathway. In this study, we found the role of Candesartan cilexetil targeting at SHP-1. The results indicate that Candesartan cilexetil was a competitive inhibitor to SHP-1(IC₅₀=85.6 μmol/L and K_i=24 μmol/L). We also found that Candesartan cilexetil was more sensitive towards SHP-1 compared with other PTPs. Through the consequence of Western blotting, it showed that Candesartan cilexetil can strengthen the level of tyrosine phosphorylation of several key cellular proteinssuch as insulin receptor(IR), insulin receptor substrate(IRS) and ERK] in insulin signaling pathway in HepG₂ cells and improve the insulin sensitivity through inhibiting the protein phosphorylation of SHP-1. These findings showed that Candesartan cilexetil might be an important inhibitor of SHP-1 and had a great application potential in the treatment of diabetes through inhibiting the level of SHP-1 in insulin signaling pathway.