Butyrate stimulates cyclin D and p21 and inhibits cyclin-dependent kinase 2 expression in HT-29 colonic epithelial cells.

Sodium butyrate, a product of colonic fermentation of dietary fiber, has been shown to inhibit cell proliferation by blocking the cells in the G1 phase of the cell cycle. However, its mechanism of action is still unknown. We found that butyrate strongly stimulated cyclin D and p21/WAF1/CIP1 expression in HT-29 human colonic adenocarcinoma cells, in a dose dependent manner. These stimulations were associated with a decrease in cyclin-dependent kinase (cdk) 2 level, whereas cdk4 and cdk6 remained unchanged. Our results suggest that the inhibition of cell cycle progression by sodium butyrate may be explained by a modulation of cell cycle regulatory proteins such as cyclin D and p21.