Fig. 3.

Antiproliferative effects of Methylbenzoprim and Pyrimethamine on Mel501 and MeWo cell lines. Viability of drug-treated Mel501 (left) and MeWo (right) cell lines was evaluated at 24, 48 and 72 h by MTS assay. Each value is normalized to untreated cells. Data are the means ± S.D. of three independent experiments bars, SD. *, P < 0.05; **, P < 0.01, *** P < 0.001 significance compared with untreated cells. We observed a time- and dose-dependent decrease of cell proliferation in Pyr and MBP treated cells, but at different doses (from 0.8 to 64 μg/ml). In particular, after 72 h of exposure Mel501 showed an IC₅₀ of 0.8 μg/ml for MBP, indicating a much higher activity of this agent with respect to Pyr, characterized by an IC₅₀ ranging between 16 and 32 μg/ml. Similarly, MeWo cells resulted in much more susceptibility to the antiproliferative effects of MBP, since the IC₅₀ of this agent ranged between 4 and 8 μg/ml as compared with that of Pyr (32–64 μg/ml)