Figure 1. Cell viability is reduced by 5-FU, curcumin and the combination treatment in HCT116, HCT116+ch3 and the corresponding 5-FU resistant cell lines.

HCT116, HCT116+ch3, HCT116R and HCT116+ch3R cell lines were treated with different concentrations of 5-FU (0, 1, 5, 10 and 20 µM) alone (A) for 24 hours, different concentrations of curcumin (0, 1, 5, 10 and 20 µM) alone (B) for 24 hours, or were pre-treated with curcumin 5 µM for 4 h, and then exposed to different concentrations of 5-FU (0, 0.1, 1, 2, 4) for 24 hours (C). Cell viability was measured with the MTT method and IC₅₀ determined at 50% growth inhibition. The results are provided as mean values with standard deviations from at least three independent experiments. Values were compared to the control and statistically significant values with p<0.05. Significant values are marked with (*).