Fig. 3
Synergistic antiproliferative effect induced by VPA/5′-DFUR combination plus 2 Gy RT in CRC cell lines. HT29 and SW620 cells were treated or untreated with VPA 1 mM and 5′-DFUR at the indicated concentrations, corresponding to IC30 at 96 h for 24 h and then with or without 2 Gy RT; a Clonogenic assay shows the long-term effects of combination treatment VPA/5′-DFUR plus 2 Gy RT on CRC cell lines HT29 and SW620 collected 12–14 days after RT. A photograph of one well in a representative experiment is shown for each treatment; bar graphs show the area of colony with diameter > 250 μm (mean ± SD of 2 or more separate experiments each one with technical triplicate). * = p < 0.05; ** = p < 0.006; *** = p < 0.0005. b DNA damage was analyzed in HT29 and SW620 by visualizing DSB marker γH2AX foci. Cells treated for 24 h with or without VPA and/or 5′-DFUR at the indicated concentrations, corresponding to IC30 at 96 h and then with or without 2 Gy RT, were collected 24 h after RT. Cells were fixed, stained for γH2AX (green) and DAPI for nuclei (blue) and observed by microscope. Representative images show γH2AX-positive nuclear foci cells with 63× magnification