Background: A small percent of patients with colorectal cancer (CRC) respond to 5-Fluorouracil (5-FU), as a first line of chemotherapy. In this study in, in order to design a new chemotherapy protocol, the effect of 5-FU and acriflavine (ACF) cotreatment on mortality rate of CRC cell lines was investigated.

Materials and Methods: Cytotoxicity of 5-FU and ACF against CRC cell lines (LS174T, SW480 and HCT116) was detected using MTT assay. Cells were treated with different concentrations of 5-FU (0.5-64 µM) or ACF (0.07-5 µM) for 72 hours and then cell viability and drugs IC50 was calculated. To assess the effect of ACF on anticancer activity of 5-FU, cells were cotreated with different concentrations of 5-FU and IC30 concentration of ACF.

Results: ACF and 5-FU suppress the viability of CRC cell lines in dose-dependent manner. 5-FU and ACF have most cytotoxic effect on LS174T and the lowest cytotoxic effect on SW480 cells. Cotreatment of ACF with 5-FU could not significantly change the sensitivity of cells against 5-FU (p>0.05).

Conclusion: In this study, the fatal and cytotoxic effect of ACF on three CRC cell lines was shown. However, cotreatment of ACF with 5-FU could not improve the anticancer activity of 5-FU.