Involvement of BCL-2 in glucocorticoid-induced apoptosis of human pre-B-leukemias

Abstract

To determine the role of BCL-2 in the glucocorticoid-induced apoptosis of lymphocytes, we analyzed the effect of glucocorticoid on two human pre-B-cell lines which express different levels of BCL-2. Glucocorticoid treatment of the 380 cell line which expresses high levels of BCL-2 resulted in inhibition of cellular proliferation without induction of apoptosis. On the other hand, glucocorticoid treatment of the 697 cell line which expresses lower levels of the BCL-2 resulted in both inhibition of cellular proliferation and apoptosis with characteristic internucleosomal DNA cleavage. The glucocorticoid-induced inhibition of cellular proliferation in both cell lines was also associated with repression of the c-myc mRNA expression. Taken together, our data suggest that BCL-2 blocks the glucocorticoid-induced apoptosis of the 380 pre-B-lymphocytes by extending their survival when the level of c-myc expression is repressed. Also by repressing the expression of c-myc, glucocorticoid causes apoptosis of the 697 pre-B-lymphocytes in the absence of high level of BCL-2 expression.