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KMID : 1140120060110030151
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Cancer Prevention Research
2006 Volume.11 No. 3 p.151 ~ p.161
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Experimental Approaches to Assess Dietary Fibre-mediated Mechanisms of Chemoprotection:In vitro Studies with Human Colon Cells in Culture
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Beatrice L. Pool-Zobel
Michael Glei
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Abstract
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Dietary fibres have been shown to reduce colorectal cancer (CRC) risks, although the epidemiological data is controversial. Obviously, studies are needed to analyse more in depth the role of these important food ingredients in cancer prevention. Dietary fibres reach the colon unaltered, where they are fermented by the gut flora to yield products such as short chain fatty acids. Of these, butyrate inhibits growth of colon cancer cells, a mechanism related to tumour suppression. This review describes an experimental approach on how to characterise different plant foods for their capacity to yield butyrate and how to study the fermentation products for biological activities in human colon cells. Batch culture fermentations with human faces and fibres were performed under anaerobe incubation conditions. The supernatants were added to human colon cells in culture and parameters of chemoprotection (antigenotoxicity, cell
growth kinetics, gene expression patterns, activities of enzymes, cells death and content of short chain fatty acids (SCFA)) were measured. A marked increase of SCFA was detected in fermentations from inulin-type fructans and whole wheat. The samples inhibited growth of tumour cells in vitro, partly due to their content of butyrate and propionate. Other growth inhibitory components are unknown and still need to be identified. Samples from fermented isolated wheat arabinoxylans did not inhibit growth of tumour cells, compared to the faeces control, but enhanced the activity of glutathione S-transferases, a cellular detoxifying system. These fermentation samples also reduced the genotoxicity of 4-hydroxynonenal, pointing to antigenotoxic effects. Using this approach, dietary fibres may be investigated for
potential chemoprotective properties in human colon cells. This will reveal mechanisms of actions that can be assessed in later studies in vivo. These types of studies are needed to elucidate the roles of non-soluble dietary ingredients in cancer initiation, progression and prevention. (Cancer Prev Res 11, 151-161, 2006)
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KEYWORD
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Dietary fibre, Probiotics, Prebiotics, Gut flora, Fermentation products, Tumour cell growth
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