Fig. 4

Co-treatment with vincristine and SAHA induced mitochondrial membrane potential loss, caspase activation, and HDAC activity. a The mitochondrial membrane potential was measured by the flow cytometry analysis of rhodamine 123. The MOLT-4 cells were stained with 10 μM rhodamine 123 and incubated at 37 °C for 30 min in the presence of SAHA alone (500 nM), vincristine alone (3 nM), or coexistence of both at different time intervals (12, 24, 36, and 48 h). The horizontal axis shows the relative fluorescence intensity and the vertical axis presents the cell number. b MOLT-4 cells were treated with different concentrations of vincristine (0.3, 1, and 3 nM) alone, a single concentration of SAHA (500 nM) alone, and a combination with both drugs for 24 and 48 h. Then, the cell lysates were collected for western blot analysis to detect the Bcl-2 family protein levels. c Cells were incubated with vincristine and SAHA for 48 h, and caspase 3, 6, 7, 8, and 9 activations and PARP cleavage were detected. d Similarly, the total cell lysates were analyzed to measure HDAC1, HDAC2, HDAC3, and HDAC6 expression and HDAC activity (H3 acetylation). Data are expressed as mean values ± SD of at least three separate determinations. S SAHA, V vincristine