Improved endometrial assessment using cyclin E and p27

To evaluate endometrial expression of cyclin E and p27 in fertile and infertile women. Retrospective clinical study. University medical center and private practice. Thirty-three fertile volunteers, 83 women seeking infertility treatment, and 23 women undergoing mock cycles. Endometrial biopsy. Cyclin E and p27 immunohistochemistry. Glandular cyclin E and p27 expression dramatically changed in intensity and subcellular localization throughout the menstrual cycle. In normal control biopsies, glandular cyclin E progressed from the basal to the lateral cytoplasm (midproliferative phase) to the nucleus (days 18 to 19) and was absent in biopsies after day 20. First appearing on days 17 to 19, p27 was found only in the nuclei. Cyclin E was more frequently seen after day 20 in infertility patients. In the hyperstimulated cycles, staining for cycle E in proliferative samples was more intense than in the natural cycles, but p27 staining was unchanged. Cyclin E and p27 may be clinically useful markers of development in the endometrium. As cell cycle regulators, cyclins reveal underlying biochemical processes driving endometrial progression and may partly represent the means by which estrogen and progesterone regulate this dynamic tissue.