LOCALIZATION OF MINERALOCORTICOID RECEPTOR AND 11-BETA-HYDROXYSTEROIDDEHYDROGENASE TYPE-II IN HUMAN BREAST AND ITS DISORDERS

Mineralocorticoid receptors have been detected in the normal human bre ast and breast cancers. The expression of mineralocorticoid receptor ( MR) and 11beta-hydroxysteroid dehydrogenase type II (11sHSD2), which c onfers specificity on MR for aldosterone, was examined by immunohistoc hemistry in 224 samples from normal human breast and benign and malign ant breast lesions in order to study its possible biological significa nce. MR and 1lsHSD2 were immunolocalized in the ductal epithelium in 3 9/40 (98 %) and 36/40 cases (90 %) of normal breast, 21/22 (95%) and 1 5/22 cases (68%) of fibrocystic changes, and 11/11 (100% %) and 8/11 ( 73 %) cases of fibroadenoma, respectively. Cases positive for II sHSD2 also expressed MR but the patterns of expression varied greatly among examples of normal breast and benign breast diseases. There was a sig nificant correlation between labeling indices of MR and 11sHSD2 in nor mal breast (p<0.01) and in benign breast disease (fibrocystic change ( p<0.05) and fibrondenoma (p<0.05)). In invasive carcinomas, immunoreac tivity for MR and I1sHSD2 was detected in malignant cells in 32/41(78% ) and 16/41(39%) cases. Both MR and 11sHSD2 labeling indices were sign ificantly higher in invasive ductal carcinoma (22 cases) than invasive lobular carcinoma(19 cases) (p<0.01). There was a significant correla tion between labeling indices of MR and 11sHSD2 when analyzing all inf iltrating carcinomas (p<0.01), but not when assessing invasive lobular or invasive ductal carcinomas separately. These results indicate that the 11 sHSD2 enzyme generally colocalizes with the MR in the ductal e pithelial cells of human breast, which may allow aldosterone to occupy its physiological receptor, and the expression of MR and 11sHSD2 appe ars to be related to ductal differentiation of breast carcinomas.