Curcumin Enhances the Efficacy of 5-FU in Colo205 Cell Lines ^†

5-FU is the main antimetabolite drug used in treating colon cancer. However, treatment success is only 10–15% due to drug resistance. To avoid resistance and improve treatment efficacy without increasing general toxicity, activity of combining curcumin with 5-FU in Colo205 cells was investigated for the first time with a real-time cell analyzer system. The cytotoxicity of 5-FU on Colo205 cells alone and in combination with curcumin were evaluated using the xCELLigence system. API-1 was used as positive control. Colo205 cells (25,000 cells/well) treated with 5-FU (1; 4; 8; 16; 32; 64 μM), API-1 (12.5; 25; 50 μM) and curcumin (25; 50 μM) 24 h after cell seeding. Cell viability was monitored for 48 h post-treatment and IC50 values were calculated using xCELLigence software. Concentrations used in the combination were determined as, 64 μM 5-FU, 50 μM curcumin and 25 μM API-1. Due to cytotoxic effect profile similarity between curcumin and protein kinase inhibitor API-1; when used in combination with 5-FU, curcumin was observed to increase the efficacy of 5-FU and accelerate the cytotoxic effect by removing the cytostatic period seen in the first 6 h. The study results show that the combination of 5-FU and curcumin in Colo205 can reduce the dose by increasing the cytotoxic activity of 5-FU and reducing the resistance to the anticancer drug.