The fermented non-digestible fraction of common bean (Phaseolus vulgaris L.) triggers cell cycle arrest and apoptosis in human colon adenocarcinoma cells.

Cancer is a leading cause of death worldwide with colorectal cancer (CRC) ranking as the third contributing to overall cancer mortality. Non-digestible compounds such as dietary fiber have been inversely associated with CRC in epidemiological in vivo and in vitro studies. In order to investigate the effect of fermentation products from a whole non-digestible fraction of common bean versus the short-chain fatty acid (SCFAs) on colon cancer cells, we evaluated the human gut microbiota fermented non-digestible fraction (hgm-FNDF) of cooked common bean (Phaseolus vulgaris L.) cultivar Negro 8025 and a synthetic mixture SCFAs, mimicking their concentration in the lethal concentration 50 (SCFA-LC50) of FNDF (hgm-FNDF-LC50), on the molecular changes in human colon adenocarcinoma cells (HT-29). Total mRNA from hgm-FNDF-LC50 and SCFA-LC50 treated HT-29 cells were used to perform qPCR arrays to determine the effect of the treatments on the transcriptional expression of 84 genes related to the p53-pathway. This study showed that both treatments inhibited cell proliferation in accordance with modulating RB1, CDC2, CDC25A, NFKB and E2F genes. Furthermore, we found an association between the induction of apoptosis and the modulation of APAF1, BID, CASP9, FASLG, TNFR10B and BCL2A genes. The results suggest a mechanism of action by which the fermentation of non-digestible compounds of common bean exert a beneficial effect better than the SCFA mixture by modulating the expression of antiproliferative and pro-apoptotic genes in HT-29 cells to a greater extent, supporting previous results on cell behavior, probably due to the participation of other compounds, such as phenolic fatty acids derivatives and biopetides.

Fermented nondigestible fraction from common bean (Phaseolus vulgaris L.) cultivar Negro 8025 modulates HT-29 cell behavior.

The aim of the study was to evaluate the effect of a fermented nondigestible fraction (FNDF) of cooked bean (Phaseolus vulgaris L.) cultivar Negro 8025 on human colon adenocarcinoma HT-29 cell survival. Negro 8025 was chosen for in vitro fermentation based on comparison of chemical composition with 2 other cultivars: Azufrado Higuera and Pinto Durango. Negro 8025 had 58% total dietary fiber, 27% resistant starch, and 20 mg of (+)-catechin equivalents per gram of sample. Short-chain fatty acids (SCFAs) production and pH of the medium were measured after fermentation as indicators of colon protection through induced arrest on cell culture and apoptosis. Butyrate and pH of FNDF of Negro 8025 were higher than the control fermented raffinose extract. The FNDF inhibited HT-29 cell survival in a time- and concentration-dependent manner. The lethal concentration 50 (LC(50)) was 13.63% FNDF (equivalent to 7.36, 0.33, and 3.31 mmol of acetic, propionic, and butyric acids, respectively). DNA fragmentation, an apoptosis indicator, was detected by the TdT-mediated dUTP nick end labeling method in cells treated with the LC(50)-FNDF and a synthetic mixture of SCFAs mimicking LC(50)-FNDF. Our results suggest that common bean is a reliable source of fermentable substrates in colon, producing compounds with potential chemoprotective effect on HT-29 colon adenocarcinoma cells, so it may present an effective alternative to mitigate colon cancer development.