Activated mTOR/P70S6K Signaling Pathway Is Involved in Insulinoma Tumorigenesis

Abstract

Background Insulinoma was a rare tumor and its pathogenesis was poorly understood. There had no study that focused on the role of mTOR signaling pathway in insulinoma tumorigenesis. Materials and methods Expression of p-mTOR and its downstream p-P70S6K in insulinoma and normal pancreatic tissue was evaluated by immunohistochemical staining and Western blotting. In vitro study, an insulinoma cell line (INS-1) was treated with inhibitors of mTOR (rapamycin) or dual PI3K/mTOR inhibitor (NVP-BEZ235), RT-PCR, and Western blotting were applied to evaluate their influence on the expression of mTOR and P70S6K. Cell proliferation was evaluated by MTT test, cell cycle and apoptosis were analyzed by flow cytometry, insulin secretion level was evaluated by GSIS method. Results Positive expression of p-mTOR and p-P70S6K was much higher in insulinoma tumor specimens than the normal pancreatic islet (P Conclusion mTOR/P70S6K signaling pathway is involved in tumorigenesis of insulinoma, NVP-BEZ235 and rapamycin offer a promising role as novel drugs in treatment of insulinoma.