Expression of progesterone receptor form A and B mRNAs in uterine leiomyoma

This study was designed to determine the expression pattern of progesterone receptor form A (PR-A) and B (PR-B) mRNAs in uterine leiomyoma. Approximately equal expression of PR-A and PR-B mRNAs was designated as type AB and dominant expression of PR-B mRNA as type B. In all cases of normal uterine myometrium, PR mRNA expression was type AB. Alteration to type B in the superficial part of uterine leiomyoma was observed in approximately 40% of cases. Therefore, the relative overexpression of PR-B mRNA in the surface of uterine leiomyoma might reveal an activated phenotype of progestational proliferation, plausibly related to the growth of uterine leiomyoma.