Endometrial levels of insulin-like growth factor-1 receptors and insulin-like growth factor binding protein-1 in perimenopausal simple endometrial hyperplasia

Abstract

The objective of this study was to evaluate the endometrial levels of insulinlike growth factor-1 (IGF-1) receptors and insulin-like growth factor binding protein-1 (IGFBP-1) in perimenopausal simple endometrial hyperplasia and in proliferative endometrium. Because unopposed estrogen stimulation is a risk factor for hyperplasia and cancer of the endometrium, it is possible that estrogen-mediated effects on IGF-1 receptors and IGFBP-1 may play an important role in the development of endometrial hyperplasia. Tissue samples were taken from 179 women >35 years of age seeking treatment for menometrorrhagia. Twenty-six of the endometrial samples revealed simple hyperplasia and 18 specimens that showed proliferative endometrium were included as a control group. All patients in both of the groups had normal body mass indexes and fasting serum insulin levels. Endometrial levels of IGF-1 receptors were measured by the labelled ligand receptor complex technique, and levels of IGFBP-1 were assessed by delayed tracer addition radioimmunoassay. Endometrial IGF-1 receptor levels in proliferative endometrium and simple hyperplasia were 16.94 +/- 5.02 and 17.18 +/- 4.12 nmol/mg, respectively, whereas IGFBP-1 levels were 1,760.19 +/- 461.33 and 2,092.77 +/- 334.47 mU/ml, respectively. Although IGF-1 receptor levels in proliferative endometrium showed no statistical difference from hyperplastic endometrium, IGFBP-1 levels in the hyperplasia group were significantly higher when compared with those levels in proliferative endometrium (p < 0.05). Our data illustrate possible estrogen effects on endometrial IGFBP-1 levels and suggest that IGFBP-1 may play an important role in regulating endometrial growth in both normal and hyperplastic endometrium.