Expression of IGF-1 receptor in KIT/PDGF receptor-α wild-type gastrointestinal stromal tumors with succinate dehydrogenase complex dysfunction.

KIT/PDGF receptor-alpha (PDGFRA) wild-type (WT) gastrointestinal stromal tumors (GIST) are characterized by an overexpression of IGF-1 receptor (IGF1R) at the mRNA and protein level. More recently, germline and somatic mutations in succinate dehydrogenase (SDH) subunits A, B and C have been identified in KIT/PDGFRA WT sporadic GIST. Until now, the molecular basis of IGF1R overexpression in KIT/PDGFRA WT GIST has not been explained. In this brief report we investigate the status of the SDH complex at the genomic and protein level in relation to IGF1R expression at the mRNA and protein level in seven KIT/PDGFRA WT sporadic GIST patients. We found that IGF1R was upregulated in all patients harboring SDH mutations or displaying a SDH dysfunction, with respect to KIT/PDGFRA WT GIST without SDH mutations. Western blot analysis confirmed that all patients with an upregulation of IGF1R mRNA had detectable IGF1R protein expression. This report would suggest that IGF1R overexpression in KIT/PDGFRA WT GIST could be driven by the loss-of-function of the SDH mitochondrial complex.