BCL-2 EXPRESSION IN NORMAL ENDOMETRIUM DURING THE MENSTRUAL-CYCLE

Bcl-2 is a proto-oncogene initially described in the (14;18) transloca tion in follicular lymphoma. It has been shown to prolong cell surviva l by preventing apoptosis. Endometrium undergoes rapid proliferation a nd differentiation under hormone control and is thus an excellent mode l to study the hormone dependency of Bcl-2 expression. We studied Bcl- 2 expression by an immunohistochemical method in 53 samples of normal endometrium randomly distributed throughout the menstrual cycle, as we ll as five samples of hyperplastic endometrium. Bcl-2 staining predomi nated in glandular cells and peaked at the end of the follicular phase Bcl-2 expression disappenred at the onset of secretory activity. The stroma, surface lining epithelium and arterial vessels also displayed cyclic variations in Bcl-2 expression. These results strongly suggest hormone-dependent regulation of Bcl-2 expression, which could play an important role in tumorigenesis.