It is well known that cellular proliferation of endometrial epithelial and stromal cells are increased in patients with endometriosis in vitro. Apoptosis plays a critical role in maintaining tissue homeostasis and represents a normal function to eliminate excess or dysfunctional cells. The BCL-2 family and Fas/FasL system have been extensively studied in human endometrium. Eutopic endometrium with endometriosis has some fundamental differences compared with normal endometrium without endometriosis, for examples apoptosis. The Ki-67 protein is a nuclear and nucleolar protein, which is tightly associated with somatic cell proliferation. We investigated the expression of Ki-67 and BCL-2, and measured cell proliferation in endometrium with or without endometriosis. Informed consent was obtained for endometrial biopsy from 2 groups of woman. The subjects were 20 samples. The study groups were 10 samples, which consisted of endometrial tissue with endometriosis. The remaining 10 samples were control group, which consisted of endometrial tissue without endometriosis. Expression of Ki-67 and BCL-2 was immunohistochemically investigated by polyclonal antibody. Tissue samples were subjectively scored on a five-point scale by two independent observers. Evaluation of staining was performed by evaluation nomogram (Ota and Igarashi, 1993). Statistical analysis was performed using the independent t-test. P < 0.05 was considered to be statistically significant. Endometrial cells were cultured in 37°C incubator and the MTT colorimetric assay was used to detect cell proliferation after 72 h of incubation. In study group, expression of Ki-67 was significantly higher than that in the control group. But expression of BCL-2 was significantly lower than that in the control group. Cell proliferation was significantly increased in endometriosis group (P < 0.05). Our data may suggest that decreased BCL-2 expression may enhance proliferation of eutopic endometrial cells with endometriosis. Therefore, it was believed to correlated with pathological abnormalities in endometriosis.
