DIM induces cell cycle arrest at G1 or G2/M phases and inhibits [
H]thymidine incorporation in HT-29 cells. (A) Cells were plated in 6-well plates at 200,000 cells/well with DMEM/F12 supplemented with 10% FBS. 24 h after plating, the monolayers were serum-deprived for 24 h with DMEM/F-12 containing 1% FBS. After serum deprivation, cells were incubated for 12 h in serum deprivation medium containing 10, 20 or 30 μmol/L DIM. The nuclei were stained with propidium iodide and the cell cycle was analyzed via flow cytometry. (B) Cells were plated at a density of 6,000 cells/well in 96-well plates and serum-deprived, then incubated for 9 h in serum deprivation medium containing 0, 10, 20 or 30 μmol/L DIM. [3H]Thymidine was added, and the cells were incubated for an additional 3 h to measure the incorporation into DNA. Each bar represents the mean ± SEM (n = 6). Comparisons between groups that yielded significant differences (P < 0.05) are indicated by different letters above each bar.