Figure 3

Sodium butyrate enhances the cytotoxic effects of etoposide, and the effect is more dramatic in MCF-7 cells than in HEK293 cells. (A) MCF-7 and HEK293 cells were pre-treated with DMSO vehicle or 2 mM sodium butyrate for 4 h, and then were treated with vehicle control or 0.5 μM etoposide for 20 h. After the treatment period, cells were re-seeded for colony forming assay and grown for 15 days. The colonies were stained with 0.5% methylene blue for visualization. Results are representative of 3 independent experiments. (B) HEK293 and MCF-7 cells were treated for 4 h with 0, 0.5, 2.0, or 8.0 mM sodium butyrate and then were exposed to DMSO vehicle or 0.5 μM etoposide for 20 h. After the treatment period, cells were re-seeded for colony forming assay. The fraction of surviving colonies was determined for the 0.5, 2.0, and 8.0 mM sodium butyrate groups relative to the corresponding 0 mM sodium butyrate group.*P< 0.05 and **P< 0.01 for MCF-7 versus HEK293 cells, ##P< 0.01 versus the corresponding co-treatment of 0.5 mM sodium butyrate plus etoposide in MCF-7 cells. Results represent the means + SD of quadruplicate experiments.