Figure 3

BCL2 family protein expression and functional analysis. BCL2A1 and ABCB1 limit response to ABT-737 but not obatoclax. (A) DAOY, UW228-3 and MED1 cells were analysed by Western blotting for expression of anti-apoptotic BCL2 protein family member, BCL2 is expressed in DAOY and MED-1 whereas no expression was observed in UW228-3 cells. MCL1 is expressed in DAOY and UW228-3 whereas MED-1 displayed no expression. BCL2A1 was expressed at a low level in all three cell lines. β-tubulin served as a loading control. (B, C) Clonogenic survival of MB cells in the presence of ABT-737 (B) or obatoclax (C) alone (dotted line) or in combination with 10 μM VPL (solid lines). Although IC₅₀ values were not reached, significant potentiation of ABT 737 function was observed at 50 μM concentration in combination with VPL in DAOY and MED1 cell lines (unpaired student’s t-test, ٭٭P = 0.03; ٭P = 0.02 respectively). Conversely, obatoclax IC₅₀ values were in the nanomolar range for all 3 cell lines and there was no potentiation when combined with VPL. Results from B and C represent mean ± SEM of n ≥ 3 experiments, all performed in duplicate.