Expression of the cyclin-dependent kinase inhibitor p27Kip1 in eutopic endometrium and peritoneal endometriosis

OBJECTIVE: This study was undertaken to evaluate the immunohistochemical expression of the cell cycle inhibitor p27Kip1 and proliferation marker Ki67 in peritoneal endometriosis and eutopic endometrium. DESIGN: Prospective study. SETTING: University hospital. PATIENT(S): Thirty-one patients with peritoneal endometriosis. INTERVENTION(S): During laparoscopy, 25 samples of predominantly red peritoneal lesions and 27 samples of predominantly black peritoneal lesions were collected from 31 patients with endometriosis. Eutopic endometrium from 25 patients with endometriosis was collected by curettage during laparoscopy or just after surgery. MAIN OUTCOME MEASURE(S): The percentage of glandular and stromal cells exhibiting positive staining for p27Kip1 and Ki67 (labeling index, LI) was determined. RESULT(S): The LI of stromal cells in red peritoneal lesions for both p27Kip1 and Ki67 was similar to that of proliferative eutopic endometrium. Although the LI of glandular epithelial cells for Ki67 in red lesions was comparable to that of proliferative eutopic endometrium, the LI for p27Kip1 was significantly higher. Furthermore, we detected a significantly higher LI of glandular epithelial and stromal cells for p27Kip1 in black lesions compared with red lesions. CONCLUSION(S): Our results suggest that expression of the cyclin kinase inhibitor p27Kip1 is involved in the natural history and progression of peritoneal endometriosis.