Dual Modes of Death Induced by Etoposide in Human Epithelial Tumor Cells Allow Bcl-2 to Inhibit Apoptosis without Affecting Clonogenic Survival

摘要: Abstract The Bcl-2 oncoprotein, which is expressed in a variety of human malignancies, blocks apoptosis induced by chemotherapeutic drugs, including the topoisomerase II inhibitor, etoposide. To determine significance etoposide-induced death epithelial tumor cells, HeLa S3 cells were transfected with bcl-2 cDNA pSFFV expression vector, and stable Bcl-2-expressing clones established. In agreement previous studies, inhibited loss cell viability (by trypan blue exclusion), appearance morphologically apoptotic amount low molecular weight DNA extracted after etoposide exposure (25 µm, 4 h). degree inhibition, compared to wild-type vector control-transfected clones, differed according level protein two studied. However, when survival was assessed colony-forming assays, no significant differences detected at any concentrations used. Although apoptosis, it had effect on formation giant, multinucleated characteristic mitotic catastrophe. Consequently, ability prevent caused drugs may not necessarily translate into increased that express Bcl-2.