Fig. 8

Methylbenzoprim is a potent dihydrofolate reductase inhibitor. Flow cytometric and cell cycle analyses on Mel501 treated with Pyr (8 μg/ml), MBP (0.8 μg/ml) and LV (10 ug/ml) for 24, 48 and 72 h. Flow cytometric data showed: i) LV was only partly able to counteract apoptotic effects induced by Pyr, whereas apoptosis was significantly abrogated at all time points of MBP treatment (a); ii) the increased expression of caspase-8 (b), caspase-9 (c) and caspase-3 (d) in both treatments (MBP and Pyr) was significantly reduced in the presence of LV (b-d) Columns, mean values of three independent experiments; bars, SD. *, P < 0.05; **, P < 0.01, *** P < 0.001 significance compared with Pyr and MBP treated cells. Pie charts (e) show the distribution of cells in each phase of the cell cycle: S-phase (dark grey), G2/M (white) and G0/G1 (grey), obtained from three independent experiments. In particular, LV administration hindered the S-phase cell cycle arrest induced by both Pyr and MBP (e)