In vitro culture with prednisolone increases BCL-2 protein expression in adult acute lymphoblastic leukemia cells

The presence of BCL-2 gene rearrangement has been detected also in cellular populations lacking the t(14;18) chromosomal translocation, such as B-lineage acute lymphoblastic leukemia (ALL) cells. It has been reported that overexpression of BCL-2 is related to resistance to glucocorticoid-induced apoptosis. In this study, we aimed to evaluate whether in vitro culture with prednisolone (PDN) could modify the expression of BCL-2 protein. ALL cells from 21 patients were incubated for 72 hr with or without a minimally lethal (IC12) dose of PDN. In vitro culture with PDN did not affect the percentage of positive cells, even though the mean fluorescence index was significantly increased (P = 0.0001), thus indicating a higher level of protein production. These data could suggest a possible mechanism of drug resistance after treatment with PDN.