Folate and fiber in the prevention of colorectal cancer: Between shadows and the light

Du, Wei; Li, Wen Ying; Lü, Rong; Fang, Jing

doi:10.3748/wjg.v16.i8.921

Cited by 22 publications

(19 citation statements)

References 51 publications

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“…It is possible that the reduced enzymatic activity of the MTHFR 677TT genotype may be advantageous in terms of DNA synthesis and DNA repair due to the increased availability of 5,10-methylenetetrahydrofolate in the presence of high folate levels, whereas reduced enzymatic activity may be disadvantageous in terms of the methylation reaction because lower levels of 5-methylenetetrahydrofolate may result in DNA hypomethylation due to reduced methionine synthesis in the presence of low folate levels (31). However, it still remains to be determined whether or not these genetic-nutrient intake interactions play as a causative or a preventive factor for the development of colorectal cancer (32,33).…”

Section: Discussionmentioning

confidence: 99%

Polymorphisms in genes involved in folate metabolism and plasma DNA methylation in colorectal cancer patients

Kim

Park²,

Choi³

et al. 2010

Oncol Rep

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Abstract. Aberrant methylation of promoter regions associated with gene silencing is one of the major mechanisms underlying the inactivation of tumor suppressor genes in carcinogenesis. Previous studies have proposed that methylated DNA from tumor cells is released into the circulation and might be widely used as a marker for non-invasive tumor detection. Catalytic activities of folate metabolismrelated enzymes and adequate synthesis of methyl donors are important elements for the cellular methylation reaction. In the present study, we sought to determine the following: i) genotype frequencies of MTHFR and MTR involved in folate metabolism in cases and cancer-free controls; and ii) the methylation status of three candidate genes (p16 INK4A , p73 and hMLH1) in plasma related to the folate and homocysteine levels. From genotype frequency analysis, individuals homozygous for the MTHFR 677TT genotype had a significantly reduced risk of developing colorectal cancer compared with those harboring the MTHFR 677CC genotype (OR, 0.206; 95% CI, 0.070-0.604; P=0.005), and had a lower plasma folate concentration than those with the MTHFR 677CC+CT genotype (P<0.05). Using methylation-specific PCR, p73 was shown to be more frequently methylated in the high folate group [50% (8 of 16)] than in the medium [16.7% (3 of 18)] or low folate subgroups [11.1% (2 of 18)].In conclusion, subjects with the variant MTHFR 677TT genotype appeared to have a significantly lower risk for colorectal cancer than those with the MTHFR 677CC genotype, and the methylation status of circulating p73 genomic DNA was substantially altered by the plasma folate level.

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Section: Discussionmentioning

confidence: 99%

Polymorphisms in genes involved in folate metabolism and plasma DNA methylation in colorectal cancer patients

Kim

Park²,

Choi³

et al. 2010

Oncol Rep

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“…Thirdly, most of the case -control studies reviewed in the present paper selected controls from among patients or participants of health checkups or screening, which might have resulted in various extents of selection bias among studies. Fourthly, few case -control studies have controlled for factors including intakes of dietary fiber, folate and vegetables, which have been favorably associated with colorectal cancer risk (22,23). Failure to account for these factors may result in a spurious association between physical activity and the risk of colorectal cancer.…”

Section: Main Features and Commentsmentioning

confidence: 99%

Physical Activity and Colorectal Cancer Risk: An Evaluation Based on a Systematic Review of Epidemiologic Evidence Among the Japanese Population

Pham

Mizoue

Tanaka

et al. 2011

Japanese Journal of Clinical Oncology

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Objective: Higher levels of physical activity have been consistently associated with a decreased risk of colon cancer, but not rectal cancer, in Western populations. The present study systematically evaluated epidemiologic evidence on the association between physical activity and colorectal cancer risk among the Japanese population. Methods: Original data were obtained from MEDLINE searched using PubMed or from searches of the Ichushi database, complemented by manual searches. The associations were evaluated based on the strength of evidence, the magnitude of association and biologic plausibility. Results: Two cohort studies and six case -control studies were identified. A weak to strong protective association between physical activity and colon cancer risk was observed in both cohort studies, showing a graded relationship, and among the majority of case -control studies, with some showing a dose -response relationship. The association observed in cohort studies was more consistent and stronger in men than in women and for proximal colon cancer than for distal colon cancer. A protective association with rectal cancer was found only in case -control studies, but the evidence was less consistent and weaker than that observed for colon cancer. Conclusions: Physical activity probably decreases the risk of colorectal cancer among the Japanese population. More specifically, the evidence for the colon is probable, whereas that for the rectum is insufficient.

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“…Sodium butyrate (NaBu) is a short-chain fatty acid (SCFA), which can influence a variety of physiological functions. The antineoplastic activity of SCFAs such as butyrates in colorectal carcinogenesis is produced as a consequence of a high fiber diet (5). Butyrate, as one main end-product of intestinal microbial fermentation, demonstrates the protective role of dietary fiber in the maintenance of colonic homeostasis (6).…”

Section: Introductionmentioning

confidence: 99%

Sodium butyrate restores ASC expression and induces apoptosis in LS174T cells

Zhang

Bai

Ren

et al. 2012

International Journal of Molecular Medicine

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Abstract. Sodium butyrate (NaBu) is a short-chain fatty acid (SCFA), which has been proposed as a potential anticancer agent. Apoptosis-associated speck-like protein (ASC) is a pro-apoptotic signaling factor that is subjected to epigenetic silencing in human cancers. Modulation by the aberrant methylation of CpG islands of ASC is a well-characterized epigenetic mechanism, and the methylation-induced silencing of ASC has been observed in several types of tumors. NaBu induces cell cycle arrest, markers of cell differentiation and apoptosis in colon cancer. NaBu promotes transcriptional activation by relaxing the DNA conformation and displays anti-proliferative and differentiating activity in a wide variety of cancers. Thus, we used NaBu to investigate the relationship between the status of cell proliferation and the re-expression of ASC in colon carcinoma LS174T cells. Our experiments determined ASC re-expression at the protein level using western blotting. In addition, we used reverse transcriptionpolymerase chain reaction to detect the expression levels of ASC mRNA and an MTT assay to detect the inhibitory rate of cell growth. The apoptosis rate was also detected for further validation of the re-expression of ASC. The results showed that ASC re-expression was significantly increased in the LS174 cells following NaBu treatment in a time-and dose-dependent manner. The expression of ASC also induced the apoptosis of LS174T cells. These results suggest that NaBu plays a role in the reactivation of ASC expression and that the latter promotes the apoptosis of LS174T cells.

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Folate and fiber in the prevention of colorectal cancer: Between shadows and the light

Cited by 22 publications

References 51 publications

Polymorphisms in genes involved in folate metabolism and plasma DNA methylation in colorectal cancer patients

Polymorphisms in genes involved in folate metabolism and plasma DNA methylation in colorectal cancer patients

Physical Activity and Colorectal Cancer Risk: An Evaluation Based on a Systematic Review of Epidemiologic Evidence Among the Japanese Population

Sodium butyrate restores ASC expression and induces apoptosis in LS174T cells

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