Insulin-like growth factor-I expression in normal and diseased endometrium

While the role of steroid hormones in the regulation of endometrial prolife ration and differentiation is well established, the effects of growth facto rs and their receptors in normal and neoplastic endometrium remain a matter of debate. Previous studies have documented the positive effects of insuli n-like growth factor-I (IGF-I) on epithelial cell proliferation and the act ive production of this growth factor in endometrial tissues. In view of dec reased expression of transforming growth factor-beta I (TGF-beta I), an ant agonist of IGF-I, in endometrial carcinoma, we investigated the expression of ICF-I, at both the mRNA and protein levels, and the immunoreactivity for type I IGF-I receptor in 30 formalin-fixed, paraffin-embedded tissue sampl es of normal and neoplastic endometrium, in order to possibly clarify the r ole of IGF-I in endometrial proliferation and differentiation. Our results demonstrate a reduced expression of IGF-I mRNA in endometrial carcinomas co mpared with non-neoplastic tissues, despite equivalent immunohistochemical expression of IGF-I and IGF-I receptor. Our data suggest that IGF-I and its corresponding receptor may not be directly involved in endometrial cancer cell proliferation and differentiation in vivo, though other components of the IGF-I system (e.g., IGF binding proteins) may affect endometrial malign ant transformation and tumor progression. (C) 1999 Wiley-Liss, Inc.