Expression of IGF-IEc Isoform in Renal Cell Carcinoma Tissues

Abstract

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.

Keywords: IGF-I; IGF-IEc; Insulin-like growth factor-I; clear cell RCC; renal cancer.