Figure 4.

The V1-transfected cells are resistant to chemical-induced apoptosis. (A) Cells stably transfected with V1, V2, or the control vector were treated with the apoptosis-inducing agent HA14-1 (25 μM) for 2 h, followed by cell harvesting, annexin V staining, and FACS analysis. HA14-1 induced greater rates of apoptosis in V2- (8.8%) and vector- (7.8%) transfected cells than in the V1-transfected cells (1.9%). (B) The vector-transfected cells were treated with HA14-1 (7.5 and 10 μM), C2-ceramide (100 μM), or combinations of HA14-1 and C2-ceramide (7.5 and 100 μM, or 10 and 100 μM, respectively) for 2 h, followed by apoptosis analysis. Few apoptotic cells were detected when treated with HA14-1 or C2-ceramide alone. However, much greater apoptosis was observed when the cells were treated with combinations of HA14-1 and C2-ceramide. (C) The V2-transfected cells were treated with combinations of HA14-1 and C2-ceramide (7.5 and 100 μM, or 10 and 100 μM, respectively) for 2 h, followed by apoptosis analysis. The combinations induced high levels of cell apoptosis (9.2 and 10.6%, respectively). (D) The V1-transfected cells were treated with combinations of HA14-1 and C2-ceramide (7.5 and 100 μM, or 10 and 100 μM, respectively) for 2 h, followed by apoptosis analysis. Few apoptotic cells were detected.