Hypermethylation in promoter region of retinoic acid receptor-beta gene and immunohistochemical findings on retinoic acid receptors in carcinogenesis of endometrium

In the present study, we analyzed the immunohistochemical findings for the RA receptor (RAR), retinoic X receptor (RXR) and hypermethylation of promoter-region CpG island methylation of RAR-β2. Immunohistochemistry indicated that though RXR-α and -γ were present in endometrial hyperplasia and cancer, other retinoid receptors were only weakly detected. The hypermethylation of RAR-β2 was found in 75.0% of endometrial hyperplasia samples and 92.2% of carcinomas. No normal endometria had methylation. This evidence may point to one of the reasons why endometrial hyperplasia acquires high proliferative capacity without differentiation, and the hypermethylation of RAR-β2 may occur in the early stage of endometrial carcinogenesis.