Cyclin D1 expression in high-grade endometrial carcinomas - Association with histologic subtype

Endometrial endometrioid adenocarcinoma (EC) and serous carcinoma (ESC) are associated with different epidemiologic risk factors, precursor lesions, m orphology, and survival outcomes. They also possess distinct molecular prof iles. We investigated the expression of cyclin D1, a member of the G1 cycli n family that regulates the G1/S transition in the cell cycle, and estrogen and progesterone receptors (ERs and PRs, respectively) in a group of ECs a nd ESCs matched for histological grade. We also sought to correlate the exp ression of cyclin D1 with ER and PR because cyclin D1 has been reported to stimulate transcription of ER- and PR-regulated genes (1,2). We hypothesize that cyclin D1 expression covaries with histologic subtype and is related to the expression of ER and PR. Twenty ESCs and 21 ECs were examined histol ogically and evaluated immunohistochemically for cyclin D1: ER, and PR usin g commercially available monoclonal antibodies in archival, formalin-fixed, and paraffin-embedded tissue. Three ESCs (15%) and 10 ECs (48%) expressed cyclin D1 (p = 0.02). Twelve ESCs (60%) and 16 ECs (76%) expressed ER, whic h is not significantly different. ER-positive ECs were significantly more l ikely to express cyclin D1 compared with ER-positive ESCs (p = 0.03), but a relationship between cyclin D1 and ER expression in EC was not found. We a lso did not find a significant relationship between cyclin D1 and PR expres sion. Therefore, cyclin D1 expression in poorly differentiated endometrial carcinomas is associated with endometrioid histology. This is consistent wi th pathobiologic divergence in poorly differentiated endometrial carcinomas .