Apoptosis and the expression of Bcl-2 and Bax in patients with endometrioid, clear cell, and serous carcinomas of the uterine endometrium

Objectives. Clear cell and serous carcinoma of the uterus are rare types of endometrial carcinomas. This study was designed to investigate the differe ntial occurrence of apoptosis, Bcl-2, and Bar in endometrioid, clear cell, and serous carcinomas. Methods. In a total of 28 endometrial carcinomas as well as 4 samples of no rmal postmenopausal endometria, apoptotic changes were examined using molec ular biochemical techniques. The expression of Bcl-2 and Bar proteins was a lso investigated by immunohistochemical staining with appropriate antibodie s. Results. Labeling of DNA in situ indicated that apoptotic cells were sporad ically seen in postmenopausal endometrium (5.2 +/- 2.1, n = 4). In contrast , cells undergoing apoptosis apparently were detected in endometrioid carci noma (29.3 +/- 3.7, n = 20), and their numbers increased intensely in clear cell (49.5 +/- 5.6, n = 5) and serous carcinomas (50.8 +/- 6.0, n = 3). Au toradiographic analysis revealed that high-molecular-weight DNA was predomi nant in postmenopausal endometrium. However, a DNA ladder was identified in 7 of 10 carcinomas. Although Bcl-2 was immunonegative or faintly immunopos itive in ail cases, many cases of endometrioid carcinoma (43.6 +/- 4.1%, n = 20) were immunopositive for Bar, unlike postmenopausal endometrium (17.6 +/- 6.7%, n = 4). Moreover, the number of cells expressing Bar increased in clear cell (60.4 +/- 6.5%, n = 5) and serous carcinomas (66.8 +/- 7,6%, n = 3) compared with that in endometrioid carcinoma. Conclusions. These results indicate that apoptosis occurs in a specific pop ulation of cells in different histologic components of endometrial carcinom as. The expression of Bar, but not of Bcl-2, might suggest histologic diffe rentiation in endometrial carcinomas. (C) 2001 Academic Press.