Faculty Publications

Tarn C, Rink L, Merkel E, Flieder D, Patak H, Koumbi D, Testa JR, Eisenberg B, von Mehren M, Godwin AK

Insulin-like growth factor 1 receptor is a potential therapeutic target for gastrointestinal stromal tumors

Proc Natl Acad Sci U S A, Early Ed. 2008;(June 11 2008):1-6, 6 pp.

Abstract A subset of gastrointestinal stromal tumors (GISTs) lack gain-of-function mutations in c-KIT and PDGFRa. These so-called wild-type (WT) GISTs tend to be less responsive to imatinib-based therapies and have a poor prognosis. We identified amplification of IGF1R in a SNP anal. of GIST and thus studied its potential as a therapeutic target in WT and mutant GIST. Expression of IGF1R and downstream effectors in clin. GIST samples was examd. by using immunoblots and immunohistochem. The roles of IGF1R signaling in GIST and viability were analyzed by using NVP-AEW541, an inhibitor of IGF1R, alone and in combination with imatinib, or via siRNA silencing of IGF1R. IGF1R was strongly overexpressed, and IGF1R amplification was detected at a significantly higher frequency in WT GISTs, including a pediatric WT GIST, compared with mutant GISTs (P = 0.0173 and P = 0.0163, resp.). Inhibition of IGF1R activity in vitro with NVP-AEW541 or down-regulation of expression with siIGF1R led to cytotoxicity and induced apoptosis in GIST cell lines via AKT and MAPK signaling. Combination of NVP-AEW541 and imatinib in GIST cell lines induced a strong cytotoxicity response. Our results reveal that IGF1R is amplified and the protein is overexpressed in WT and pediatric GISTs. We also demonstrate that the aberrant expression of IGF1R may be assocd. with oncogenesis in WT GISTs and suggest an alternative and/or complementary therapeutic regimen in the clin. management of all GISTs, esp. in a subset of tumors that respond less favorably to imatinib-based therapy. [on SciFinder (R)]