THE EXPRESSION OF INSULIN-LIKE GROWTH-FACTOR AND ITS BINDING-PROTEIN MESSENGER-RNA IN THE ENDOMETRIUM OF POSTMENOPAUSAL PATIENTS WITH BREAST-CANCER RECEIVING TAMOXIFEN

Background. Insulin-like growth factor I (IGF-I) is known to mediate e strogen effect in the uterus, whereas IGF binding proteins (IGFBPs) mo dulate the biologic effects of IGF-I, Tamoxifen may act via the IGF-IG FBP system in the postmenopausal endometrium. Methods, Endometrial sam ples were collected from 16 postmenopausal women with breast cancer of whom 9 received tamoxifen and the remaining 7 received no hormonal tr eatment, The expression of messenger RNA for IGF-I, IGF-II, and the IG FBPs 1-6 was studied using dot blot and Northern blot techniques. Resu lts, Expression of mRNA for IGF-I, IGFBP-2, -3, -4, and -6 was present in endometrial specimens. The expression of IGF-I mRNA was similar in the tamoxifen-treated and control patients, whereas mRNA expression f or IGF-II was not detected, The expression of IGFBP-2 and -4 mRNA pred ominated in the endometrium of patients who received tamoxifen, Conclu sions, These findings demonstrate that the IGF-IGFBP system is present in the postmenopausal endometrium and may be modulated by tamoxifen.