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OBJECTIVE-Imatinib has been reported to induce regression of type 2 diabetes in chronic leukemia patients. However, the mechanism of diabetes amelioration by imatinib is unknown, and it is uncertain whether imatinib has effects on type 2 diabetes itself without other confounding diseases like leukemia. We studied the effect of imatinib on diabetes in db/db mice and investigated possible mechanism's underlying improved glycemic control by imatinib.
RESEARCH DESIGN AND METHODS-Glucose tolerance and insulin tolerance tests were done after daily intraperitoneal injection of 25 mg/kg imatinib into db/db and C57BL/6 mice for 4 weeks. Insulin signaling and endoplasmic reticulum stress responses were studied by Western blotting. β-cell mass and apoptotic β-cell number were determined by combined terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining and insulin immunohistochemistry. The in vitro effect of imatinib was studied using HepG2 cells.
RESULTS-Imatinib induced remission of diabetes in db/db mice and amelioration of insulin resistance. Expression of endoplasmic reticulum stress markers in the liver and adipose tissues of db/db mice, such as phospho-PERK, phospho-eIF2α, TRB3, CHOP, and phospho-c-Jun NH^sub 2^-terminal kinase, was reduced by imatinib. Insulin receptor substrate-1 tyrosine phosphorylation and Akt phosphorylation after insulin administration were improved by imatinib. Serum aminotransferase levels and hepatic triglyceride contents were decreased by imatinib. Pancreatic β-cell mass was increased by imatinib, accompanied by decreased TUNEL^sup +^ β-cell and increased BrdU^sup +^ β-cell numbers. Imatinib attenuated endoplasmic reticulum stress in hepatoma cells in vitro.
CONCLUSIONS-Imatinib ameliorated endoplasmic reticulum stress and induced remission of diabetes in db/db mice. Imatinib or related compounds could be used as therapeutic agents against type 2 diabetes and metabolic syndrome. Diabetes 58:329-336, 2009
Type 2 diabetes is a metabolic disease that affects 2.8% of all age-groups worldwide, and this proportion is expected to increase to 4.4% by 2030 (1). The two major components of the pathogenesis of type 2 diabetes are insulin resistance and ß-cell failure. However, the biochemical mechanisms underlying these two phenomena are incompletely understood.
Regarding the mechanism of insulin resistance, several hypotheses have been proposed, for example, increased circulating free fatty acid level, mitochondrial dysfunction, elevated reactive oxygen species production, and increased levels of proinflammatory mediators (2-4). Downstream of these molecules or events, disturbance in intracellular signaling, such as c-Jun NH^sub 2^-terminal kinase (JNK) phosphorylation, IKKβ activation,...