Immunocytochemical study of progesterone receptors in hyperplastic and neoplastic endometrial tissues

Endometrial carcinoma is the most common genital malignancy in North America. However its pathogenesis, in particular its relationship with hyperplasia is not clear. To understand steroid hormonal interactions in the genesis and growth of human endometrial hyperplasia and carcinoma, we have assayed progesterone receptors in hyperplasia and neoplastic human endometrium by immunocytochemistry. The presence of progesterone receptors in target tissues is known to be a marker of both estrogen and progesterone action. The receptors were identified in fresh-frozen sections using a mouse monoclonal antiprogesterone receptor antibody (alpha PR6). The progesterone receptor content was high in the epithelium of hyperplasia without cytological atypia and low in the epithelium of endometrial intraepithelial neoplasia (hyperplasia with cytological atypia). In carcinomas there was a heterogenous distribution of progesterone receptors in the epithelium but low as compared to hyperplastic endometria without cytological atypia. The stroma contained relatively high progesterone receptor levels irrespective of whether the epithelium was hyperplastic or neoplastic.