Imatinib mesilate-induced phosphatidylinositol 3-kinase signalling and improved survival in insulin-producing cells: role of Src homology 2-containing inositol 5′-phosphatase interaction with c-Abl

摘要: It is not clear how small tyrosine kinase inhibitors, such as imatinib mesilate, protect against diabetes and beta cell death. The aim of this study was to determine whether imatinib, compared with the non-cAbl-inhibitor sunitinib, affects pro-survival signalling events in phosphatidylinositol 3-kinase (PI3K) pathway. Human EndoC-βH1 cells, murine TC-6 cells human pancreatic islets were used for immunoblot analysis insulin receptor substrate (IRS)-1, Akt extracellular signal-regulated (ERK) phosphorylation. Phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] plasma membrane concentrations assessed MIN6 using evanescent wave microscopy. Src homology 2-containing inositol 5′-phosphatase 2 (SHIP2) phosphorylation phosphatase tensin homologue deleted on chromosome 10 (PTEN) serine phosphorylation, well c-Abl co-localisation SHIP2, studied HEK293 by immunoprecipitation analysis. Gene expression RT-PCR. Cell viability measured vital staining. Imatinib stimulated ERK(thr202/tyr204) a c-Abl-dependent manner. Imatinib, but also IRS-1(tyr612), Akt(ser473) Akt(thr308) This effect paralleled oscillatory bursts PI(3,4,5)P3 levels. Wortmannin induced decrease levels, which slower imatinib-treated than control indicating an PI(3,4,5)P3-degrading enzymes. In line this, decreased SHIP2 PTEN. co-immunoprecipitated its binding largely reduced sunitinib. increased total β-catenin levels viability, whereas sunitinib exerted negative effects viability. inhibition decreases activity, results enhanced downstream PI3 kinase.