Sodium butyrate stimulates polyamine biosynthesis in colon cancer cells

Ornithine decarboxylase activity in tumor cell lines correlates with sensitivity to cell death induced by histone deacetylase inhibitors

Inhibitors of histone deacetylases (HDAC) show significant promise as targeted anticancer agents against a variety of hematologic and solid tumors. HDAC inhibitors arrest the growth of primary cells, but they induce apoptosis or differentiation of tumor cells. Although the precise mechanism is unknown, differences in cell cycle checkpoints and chromatin structure may be responsible. Cellular polyamines regulate both cell cycle progression and chromatin structure. In tumors, polyamines are abundantly produced because of increased activity of the rate-limiting enzyme in polyamine synthesis, ornithine decarboxylase (ODC). To determine if polyamines contribute to the cellular response to HDAC inhibitors, we inhibited ODC activity with alpha-difluoromethylornithine. Polyamine depletion increased resistance to apoptosis induced by HDAC inhibitors. In addition, we found that ODC activity levels correlated with sensitivity to HDAC inhibitors in a panel of tumor cell lines. We conclude that polyamines participate in the cellular response to HDAC inhibitors and that ODC activity correlates with sensitivity to HDAC inhibitor-induced apoptosis. Thus, elevated polyamine levels might be a biomarker for tumor sensitivity to HDAC inhibitor-induced apoptosis. These findings warrant clinical evaluation of tumor samples to determine if high ODC activity levels predict sensitivity to HDAC inhibitors.

Acetate and propionate potentiate the antiproliferative effect of butyrate on RBL-2H3 growth

1. The effect of acetate, propionate, and butyrate separately and combined on RBL-2H3 (a rat basophilic leukemic cell type) proliferation during 24, 48, and 72 hr was examined. Also, the effect of a mixture of the three volatile fatty acids on proliferation of HeLa-155 (a human adenocarcinoma), C57 B1/6J (a mouse melanoma), and MCF-7 (human breast tumor) during 8 days was investigated. 2. Acetate and propionate per se did not present any effect on RBL-2H3 growth during 72 hr, however, when acetate and propionate were added together a significant inhibition of this cell growth was found; 18% for 48 and 37% for 72 hr. The addition of butyrate to the culture medium caused a 75% decrease in the rate of this cell growth either after 48 and 72 hr. This effect of butyrate was pronounced by acetate (86% and 90% for 48 and 72 hr, respectively), propionate (87% for 48 and 93% for 72 hr), and acetate and propionate together (76% for 48 and 92% for 72 hr). 3. Daily addition of a mixture of the short-chain fatty acids (10 mM acetate, 2 mM propionate and 1.5 mM butyrate) markedly decreased the number of cells after 8 days: 58% for RBL-2H3, 42% for HeLa-155, 91% for C57 B1/6J and 55% for MCF-7. 4. These results support the proposition that a fiber-rich diet that leads to great production of butyrate but also of propionate and acetate would be more effective to prevent the occurrence of colorectal cancer than the administration of this short-chain fatty acid given alone.

Wheat bran- but not oat bran-enriched diets increase the mucosal height of the cecum and colon of newly weaned and aged rats

The effect of diets enriched with oat or wheat bran (prepared by the addition of 300 g of each fiber to 1000 g of the regular diet), given for 8 weeks, on the mucosal height of the colon and cecum was investigated. Newly weaned (21 days old) and aged (12 months old) male Wistar rats were used in this study. As compared to controls, diets enriched with wheat bran provoked a significant increase in the mucosal height, whereas oat bran did not cause any effect. In newly weaned rats (21 days old), wheat bran increased the mucosal height (microns) in the cecum by 20% (mean +/- SEM for 8 rats; 169.1 +/- 5.2 and 202.9 +/- 8.0 for control and wheat bran, respectively) and in the colon (218.8 +/- 7.2 and 264.5 +/- 18.8 for control and wheat bran, respectively). A similar effect was observed in aged rats (12 months old), with an increase of 15% in the mucosal height (microns) of the cecum (mean +/- SEM of 8 rats; 193.2 +/- 8.6 and 223.7 +/- 8.3 for control and wheat bran, respectively) and of 17% in the colon (300.4 +/- 9.2 and 352.2 +/- 15.9 for control and wheat bran, respectively).