Article

The effects of probiotics on colon cancer development.

Department of Medical Nutrition, Karolinska Institutet, NOVUM, S-141 86 Huddinge, Sweden.
Nutrition Research Reviews (impact factor: 4.84). 01/2005; 17(2):277-84. DOI:10.1079/NRR200484 pp.277-84
Source: PubMed

ABSTRACT While several effects beneficial to health have been attributed to the probiotic lactic acid bacteria, perhaps the most interesting and controversial remains that of anti-cancer activity. The vast majority of studies in this area deal with protective effects against colon cancer. There is no direct experimental evidence for cancer suppression in human subjects as a result of the consumption of probiotic cultures in fermented or unfermented dairy products. However, there is a wealth of indirect evidence, based largely on laboratory studies. Reports in the literature, regarding the anti-cancer effects of lactic acid bacteria, fall into the following categories: in vitro studies, animal studies, epidemiological studies and human dietary intervention studies. Examples of these reports will be given in the present review. The mechanisms by which probiotic bacteria may inhibit colon cancer are still poorly understood. However, several potential mechanisms are being discussed in the literature and these will also be addressed in the present review.

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    Article: TLR2 controls intestinal carcinogen detoxication by CYP1A1.
    Khoa Nguyen Do, Lisbeth Nielsen Fink, Thomas Elbenhardt Jensen, Laurent Gautier, Alexandr Parlesak
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    ABSTRACT: Intestinal cytochrome P450 subclass 1A1 (CYP1A1) contributes to a metabolic "shield" protecting the host from ingested carcinogens such as polycyclic aromatic hydrocarbons (PAH). The expression of CYP1 (including CYP1A2 and CYP1B1) is considered to depend solely on a heterodimeric transcription factor consisting of the arylhydrocarbon receptor (AHR) and the AHR nuclear translocator (ARNT). So far, no interference has been noted between the regulation of CYP1 and the activation of Toll-like receptor 2 (TLR2), which modulates the inflammatory response to bacterial cell wall components in immune cells and enterocytes. Here we report that intestinal CYP1A1 is silenced in TLR2-deficient mice, even when under exposure to the carcinogenic PAH benzo[a]pyrene (BaP). In contrast, hepatic CYP1A1 was moderately induced in TLR2-deficient mice without restoring their ability to clear BaP from systemic circulation, as present in wild-type animals. After feeding of BaP for 21 days, only TLR2(-/-) mice, but not their wild type littermates developed polyps in the colon. Gene expressions and protein concentrations of AHR and ARNT in the intestine did not differ between the genotypes. In conclusion, the presence of ligands for TLR2 of bacterial origin seems to be crucial for detoxication of luminal carcinogens by CYP1A1 in the intestine. This unprecedented finding indicates a complex interplay between the immune system of the host and intestinal bacteria with detoxication mechanisms. This highlights the relevance of intestinal microbiota when trying to unravel pathways present in mammals and opens new perspectives for research in human health.
    PLoS ONE 01/2012; 7(3):e32309. · 4.09 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

animal studies
 
anti-cancer activity
 
anti-cancer effects
 
cancer suppression
 
direct experimental evidence
 
effects beneficial
 
epidemiological studies
 
following categories
 
human dietary intervention studies
 
human subjects
 
indirect evidence
 
laboratory studies
 
lactic acid bacteria
 
potential mechanisms
 
present review
 
probiotic lactic acid bacteria
 
protective effects
 
unfermented dairy products
 
vast majority
 
vitro studies
 

Joseph Rafter