Expression of IGF-IEc Isoform in Renal Cell Carcinoma Tissues.

BACKGROUND/AIM Insulin-like growth factor-I (IGF-I) regulates various aspects of cancer biology. There is a growing body of evidence regarding the potential distinct role of IGF-I isoforms, particularly of IGF-IEc, in the pathophysiology of various human cancer types, however, there are no studies which examined the expression of the different IGF-I isoforms in renal cell carcinoma (RCC). This study aimed to characterize the expression of IGF-IEc in human RCC tissues and investigated whether its expression is associated with the histopathological type of RCC as well as with the overall survival of patients. MATERIALS AND METHODS Formalin-fixed paraffin-embedded renal tissue samples from 94 patients (58 males and 36 females) were assessed for IGF-IEc expression by immunohistochemistry. RESULTS RCC tissues showed mainly cytoplasmic IGF-IEc staining but immunoreactivity of IGF-IEc was also localized in the cell membrane. Significantly lower IGF-IEc expression was found in clear cell RCC vs. all other histological types (p=0.010), and this remained significant after adjusting for tumor size, grade, stage, and mitotic index (p<0.05). No association was found between IGF-IEc expression level and overall survival of patients with RCC. CONCLUSION The differential expression of IGF-IEc isoform among the RCC histopathological types may indicate its histological type-specific regulation and possibly suggests a discrete biological role of this isoform in the pathophysiology of RCC.