A candidate gene study of folate-associated one carbon metabolism genes and colorectal cancer risk

Circulating unmetabolized folic acid and 5-methyltetrahydrofolate and risk of breast cancer: a nested case-control study

BACKGROUND/OBJECTIVES

Folates found in natural foods are thought to protect against cancer. However, folic acid (FA), a synthetic form of folate used in supplements and fortified foods, may increase breast cancer risk if present in unmetabolized form (UMFA) in the circulation. This study examined the associations of serum UMFA and 5-methyltetrahydrofolate (5-mTHF), the predominant form of circulating folate, with breast cancer risk.

SUBJECTS/METHODS

We conducted a nested case-control study in a prospective cohort. In total, 553 cases of invasive breast cancer, diagnosed before mandatory FA fortification of grain in the US in 1998, were individually-matched to 1059 controls. Serum UMFA and 5-mTHF were measured using liquid chromatography-tandem mass spectrometry in stored serum samples, and 5-mTHF was corrected for storage degradation.

RESULTS

Serum UMFA was not associated with breast cancer risk: the percentage of women with detectable levels of UMFA was similar in cases and controls (18% and 20%, respectively; p = 0.46). Two tag-SNPs in the promoter region of the FA-metabolizing gene were also not associated with risk. There was a marginally significant inverse association of 5-mTHF_corrected with breast cancer risk (odds ratio for the highest vs. lowest quintile = 0.69, 95% CI = 0.49 to 0.97; p_trend = 0.08).

CONCLUSIONS

Circulating UMFA was not associated with breast cancer risk. These results apply to countries without mandatory FA food fortification. Studies are needed in countries with mandatory fortification, where levels of UMFA are much higher than in our study.

microRNA-29b inhibits cell growth and promotes sensitivity to oxaliplatin in colon cancer by targeting FOLR1

The present study was aimed to explore the functional role of microRNA (miR)-29b in colon cancer, as well as underlying mechanisms. Expressions of miR-29b and folate receptor 1 (FOLR1) were measured in both human colon tumor samples and cell lines. Colon cancer cell lines SW480 and SW620 were transfected with miR-29b mimic, antisense oligonucleotides (ASO)-miR-29b, small interfering (siRNA) against FOLR1 (si-FOLR1), or corresponding negative controls (NCs), and then were incubated with or without oxaliplatin (L-OHP). Thereafter, cell viability, cytotoxicity, cell apoptosis, and expression of FOLR1, ATP Binding Cassette Subfamily G Member 2 (ABCG2) and p-glycoprotein (p-gp) were analyzed. We found that miR-29b was significantly decreased, while FOLR1 was statistically elevated in colon cancer samples and cell lines compared to the nontumor samples and nontumourigenic immortalized human colon epithelial cell line FHC. Overexpression of miR-29b markedly inhibited cell viability, promoted sensitivity to L-OHP, stimulated cell apoptosis (all p < .05), and decreased the levels of ABCG2 and p-gp in cancer cells, whereas suppression of miR-29b showed contrary results. Moreover, we observed that FOLR1 was a direct target of miR-29b and was negatively regulated by miR-29b. In addition, the findings revealed that the effects of FOLR1 inhibition on cell viability, sensitivity to L-OHP, cell apoptosis, and the levels of ABCG2 and p-gp were similar to overexpression of miR-29b. Taken together, our study suggests that miR-29b inhibits cell growth and promotes sensitivity to L-OHP in colon cancer by targeting FOLR1.

Genome-wide association study of circulating folate one-carbon metabolites

Experimental, observational, and clinical trials support a critical role of folate one-carbon metabolism (FOCM) in colorectal cancer (CRC) development. In this report, we focus on understanding the relationship between common genetic variants and metabolites of FOCM. We conducted a genome-wide association study of FOCM biomarkers among 1,788 unaffected (without CRC) individuals of European ancestry from the Colon Cancer Family Registry. Twelve metabolites, including 5-methyltetrahydrofolate, vitamin B₂ (flavin mononucleotide and riboflavin), vitamin B₆ (4-pyridoxic acid, pyridoxal, and pyridoxamine), total homocysteine, methionine, S-adenosylmethionine, S-adenosylhomocysteine, cystathionine, and creatinine were measured from plasma using liquid chromatography-mass spectrometry (LC-MS) or LC-MS/MS. For each individual biomarker, we estimated genotype array-specific associations followed by a fixed-effect meta-analysis. We identified the variant rs35976024 (at 2p11.2 and intronic of ATOH8) associated with total homocysteine (p = 4.9 × 10^-8 ). We found a group of six highly correlated variants on chromosome 15q14 associated with cystathionine (all p < 5 × 10^-8 ), with the most significant variant rs28391580 (p = 2.8 × 10^-8 ). Two variants (rs139435405 and rs149119426) on chromosome 14q13 showed significant (p < 5 × 10^-8 ) associations with S-adenosylhomocysteine. These three biomarkers with significant associations are closely involved in homocysteine metabolism. Furthermore, when assessing the principal components (PCs) derived from seven individual biomarkers, we identified the variant rs12665366 (at 6p25.3 and intronic of EXOC2) associated with the first PC (p = 2.3 × 10^-8 ). Our data suggest that common genetic variants may play an important role in FOCM, particularly in homocysteine metabolism.

The Evolving Role of Multivitamin/Multimineral Supplement Use among Adults in the Age of Personalized Nutrition

Micronutrient deficiencies occur in segments of the adult population in the United States. Multivitamin/multimineral supplements (MVMS) are widely used by this population, which reduces inadequacies in micronutrient intake, but the potential for exceeding tolerable upper intake levels in others should be considered. There are concerns associated with the excessive intake of certain nutrients, particularly folic acid, and potential untoward consequences. The advent of nutrigenomics and the enhanced ability to directly study the interactions between nutrition and genetic variants and expression will allow for the conduct of more targeted studies with specific endpoints and may ultimately lead to progress in the field of personalized nutrition. The role of MVMS in health maintenance and chronic disease prevention remains controversial. Conducting studies in this area has been hampered by, among other factors, inconsistent definitions of MVMS, ranging from as few as three vitamins to broad-spectrum products containing more than two dozen vitamins and minerals. Results from some observational studies and large-scale, randomized, controlled trials suggest that MVMS may reduce the risk of some forms of cancer and, potentially, cardiovascular disease. The ongoing COcoa Supplement and Multivitamin Outcomes Study (COSMOS) is expected to build on this research and provide additional insights into these areas.

One-carbon genetic variants and the role of MTHFD1 1958G>A in liver and colon cancer risk according to global DNA methylation

Several polymorphic gene variants within one-carbon metabolism, an essential pathway for nucleotide synthesis and methylation reactions, are related to cancer risk. An aberrant DNA methylation is a common feature in cancer but whether the link between one-carbon metabolism variants and cancer occurs through an altered DNA methylation is yet unclear. Aims of the study were to evaluate the frequency of one-carbon metabolism gene variants in hepatocellular-carcinoma, cholangiocarcinoma and colon cancer, and their relationship to cancer risk together with global DNA methylation status. Genotyping for BHMT 716A>G, DHFR 19bp ins/del, MTHFD1 1958G>A, MTHFR 677C>T, MTR 2756A>G, MTRR 66A>G, RFC1 80G>A, SHMT1 1420C>T, TCII 776C>G and TS 2rpt-3rpt was performed in 102 cancer patients and 363 cancer-free subjects. Methylcytosine (mCyt) content was measured by LC/MS/MS in peripheral blood mononuclear cells (PBMCs) DNA. The MTHFD1 1958AA genotype was significantly less frequent among cancer patients as compared to controls (p = 0.007) and related to 63% reduction of overall cancer risk (p = 0.003) and 75% of colon cancer risk (p = 0.006). When considering PBMCs mCyt content, carriers of the MTHFD1 1958GG genotype showed a lower DNA methylation as compared to carriers of the A allele (p = 0.048). No differences were highlighted by evaluating a possible relationship between the other polymorphisms analyzed with cancer risk and DNA methylation.

The MTHFD1 1958AA genotype is linked to a significantly reduced cancer risk. The 1958GG genotype is associated to PBMCs DNA hypomethylation as compared to the A allele carriership that may exert a protective effect for cancer risk by preserving from DNA hypomethylation.

The RFC1 80G>A, among Common One-Carbon Polymorphisms, Relates to Survival Rate According to DNA Global Methylation in Primary Liver Cancers

Polymorphisms within one-carbon metabolism genes have been largely studied in relation to cancer risk for the function of this pathway in nucleotide synthesis and DNA methylation. Aims of this study were to explore the possible link among several common functional gene polymorphisms within one-carbon metabolism and survival rate in primary liver cancers, i.e., hepatocellular carcinoma and cholangiocarcinoma, and to assess the additional effect of global DNA methylation on survival rate and mortality risk. Forty-seven primary liver cancer patients were genotyped for ten polymorphisms: DHFR 19bp ins/del, TS 2rpt-3rpt, MTHFD1 1958G>A, MTHFR 677C>T, MTR 2756A>G, MTRR 66A>G, RFC1 80G>A, SHMT1 1420C>T, BHMT 716 A>G, TC II 776C>G. Methylation was determined in peripheral blood mononuclear cells (PBMCs) DNA as methylcytosine (mCyt) content using LC/MS/MS. Among the polymorphisms analysed, the RFC1 80G>A (rs1051266) influenced the survival rate in primary liver cancers. The RFC1 80AA was associated to a significantly reduced survival rate (22.2%) as compared to both GG and GA genotypes (61.5% and 76% respectively, p = 0.005). When the cancer patients were stratified according to the mCyt median value as high (>5.34%) or low (≤5.34%), the concomitant presence of AA genotype and low mCyt level led to a significantly worse survival rate as compared to the G allele carriership (p<0.0001) with a higher Hazard Ratio (HR = 6.62, p = 0.001). The subjects carrying the AA genotype in association with high mCyt did not show a significant difference in survival rate as compared with the G allele carriers (p = 0.919). The RFC1 80G>A polymorphism influenced the survival rate, and the presence of RFC1 80AA genotype with low global methylation in PBMCs DNA was associated with poorer prognosis and higher mortality risk, therefore highlighting novel molecular signatures potentially helpful to define prognostic markers for primary liver cancers.

The Influence of Screening for Precancerous Lesions on Family-Based Genetic Association Tests: An Example of Colorectal Polyps and Cancer

Unintended consequences of secondary prevention include potential introduction of bias into epidemiologic studies estimating genotype-disease associations. To better understand such bias, we simulated a family-based study of colorectal cancer (CRC), which can be prevented by resecting screen-detected polyps. We simulated genes related to CRC development through risk of polyps (G1), risk of CRC but not polyps (G2), and progression from polyp to CRC (G3). Then, we examined 4 analytical strategies for studying diseases subject to secondary prevention, comparing the following: 1) CRC cases with all controls, without adjusting for polyp history; 2) CRC cases with controls, adjusting for polyp history; 3) CRC cases with only polyp-free controls; and 4) cases with either CRC or polyps with controls having neither. Strategy 1 yielded estimates of association between CRC and each G that were not substantially biased. Strategies 2-4 yielded biased estimates varying in direction according to analysis strategy and gene type. Type I errors were correct, but strategy 1 provided greater power for estimating associations with G2 and G3. We also applied each strategy to case-control data from the Colon Cancer Family Registry (1997-2007). Generally, the best analytical option balancing bias and power is to compare all CRC cases with all controls, ignoring polyps.

The Dihydrofolate Reductase 19 bp Polymorphism Is Not Associated with Biomarkers of Folate Status in Healthy Young Adults, Irrespective of Folic Acid Intake

BACKGROUND

Dihydrofolate reductase (DHFR) is essential for the conversion of folic acid to active folate needed for one-carbon metabolism. Common genetic variation within DHFR is restricted to the noncoding regions, and previous studies have focused on a 19 bp deletion/insertion polymorphism (rs70991108) within intron 1. Reports of an association between this polymorphism and blood folate biomarker concentrations are conflicting.

OBJECTIVE

In this study, we evaluated whether the DHFR 19 bp deletion/insertion polymorphism affects circulating folate biomarkers in, to our knowledge, the largest cohort to address this question to date.

METHODS

Healthy young Irish individuals (n = 2507) between 19 and 36 y of age were recruited between February 2003 and February 2004. Folic acid intake from supplements and fortified foods was assessed with the use of a customized food intake questionnaire. Concentrations of serum folate and vitamin B-12, red blood cell (RBC) folate, and plasma total homocysteine (tHcy) were measured. Data were analyzed with the use of linear regression models.

RESULTS

Folic acid intake was positively associated with serum (P < 0.0001) and RBC (P = 0.0005) folate concentration and was inversely associated with plasma tHcy (P = 0.001) as expected. The DHFR 19 bp polymorphism was not significantly associated with either serum (P = 0.82) or RBC (P = 0.21) folate, or plasma tHcy (P = 0.20), even in those within the highest quintile of folic acid intake (>326 μg folic acid/d; P = 0.96). A nonsignificant trend toward lower RBC folate by genotype (P = 0.09) was observed in the lowest folic acid intake quintile (0-51 μg/d).

CONCLUSION

In this cohort of healthy young individuals, the DHFR 19 bp deletion allele did not significantly affect circulating folate status, irrespective of folic acid intake. Our data rule out a strong functional effect from this polymorphism on blood folate concentrations.

Folate-mediated one-carbon metabolism genes and interactions with nutritional factors on colorectal cancer risk: Women's Health Initiative Observational Study

BACKGROUND

Investigations of folate-mediated one-carbon metabolism (FOCM) genes and gene-nutrient interactions with respect to colorectal cancer (CRC) risk are limited to candidate polymorphisms and dietary folate. This study comprehensively investigated associations between genetic variants in FOCM and CRC risk and whether the FOCM nutrient status modified these associations.

METHODS

Two hundred eighty-eight candidate and tagging single-nucleotide polymorphisms (SNPs) in 30 FOCM genes were genotyped for 821 incident CRC case-control matched pairs in the Women's Health Initiative Observational Study cohort. FOCM biomarkers (red blood cell [RBC] folate, plasma folate, pyridoxal-5'-phosphate [PLP], vitamin B12, and homocysteine) and self-reported alcohol consumption were measured at the baseline. Conditional logistic regression was implemented; effect modification was examined on the basis of known enzyme-nutrient relations.

RESULTS

Statistically significant associations were observed between CRC risk and functionally defined candidate SNPs of methylenetetrahydrofolate dehydrogenase 1 (MTHFD1; K134R), 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR; P450R), and PR domain containing 2 with ZNF domain (PRDM2; S450N) and a literature candidate SNP of thymidylate synthase (TYMS; g.676789A>T; nominal P < .05). In addition, suggestive associations were noted for tagging SNPs in cystathionine-β-synthase (CBS), dihydrofolate reductase (DHFR), DNA (cytosine-5-)-methyltransferase 3β (DNMT3B), methionine adenosyltransferase I α (MAT1A), MTHFD1, and MTRR (nominal P < .05; adjusted P, not significant). Significant interactions between nutrient biomarkers and candidate polymorphisms were observed for 1) plasma/RBC folate and folate hydrolase 1 (FOLH1), paraoxonase 1 (PON1), transcobalamin II (TCN2), DNMT1, and DNMT3B; 2) plasma PLP and TYMS TS3; 3) plasma B12 and betaine-homocysteine S-methyltransferase 2 (BHMT2); and 4) homocysteine and methylenetetrahydrofolate reductase (MTHFR) and alanyl-transfer RNA synthetase (AARS).

CONCLUSIONS

Genetic variants in FOCM genes are associated with CRC risk among postmenopausal women. FOCM nutrients continue to emerge as effect modifiers of genetic influences on CRC risk.

Simultaneous quantitation of folic acid and 5-methyltetrahydrofolic acid in human plasma by HPLC-MS/MS and its application to a pharmacokinetic study

A sensitive method based on high-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS) has been developed for the simultaneous determination of folic acid (FA) and its active metabolite, 5-methyltetrahydrofolic acid (5-M-THF), in human plasma. The analytes were extracted from plasma with methanol solution containing 10 mg/mL of 2-mercaptoethanol and 0.025% (v/v) ammonium hydroxide. FA and 5-M-THF were more stable after the addition of 2-mercaptoethanol and ammonium hydroxide in the sample preparation procedures of this study than they were in the previously published methods. Chromatographic separation was performed on a Hedera ODS-2 column using a gradient elution system of acetonitrile and 1 mM ammonium acetate buffer solution containing 0.6% formic acid as mobile phase. LC–MS/MS was carried out with an ESI ion-source and operated in the multiple reaction monitoring (MRM) mode. The assay was linear over the concentration ranges of 0.249–19.9 ng/mL for FA, and 5.05–50.5 ng/mL for 5-M-THF. The developed LC–MS/MS method offers increased sensitivity for quantification of FA and 5-M-THF in human plasma and was applicable to a pharmacokinetic study of FA and 5-M-THF.

Folate Augmentation of Treatment--Evaluation for Depression (FolATED): randomised trial and economic evaluation

BACKGROUND

Folate deficiency is associated with depression. Despite the biological plausibility of a causal link, the evidence that adding folate enhances antidepressant treatment is weak.

OBJECTIVES

(1) Estimate the clinical effectiveness and cost-effectiveness of folic acid as adjunct to antidepressant medication (ADM). (2) Explore whether baseline folate and homocysteine predict response to treatment. (3) Investigate whether response to treatment depends on genetic polymorphisms related to folate metabolism.

DESIGN

FolATED (Folate Augmentation of Treatment - Evaluation for Depression) was a double-blind and placebo-controlled, but otherwise pragmatic, randomised trial including cost-utility analysis. To yield 80% power of detecting standardised difference on the Beck Depression Inventory version 2 (BDI-II) of 0.3 between groups (a 'small' effect), FolATED trialists sought to analyse 358 participants. To allow for an estimated loss of 21% of participants over three time points, we planned to randomise 453.

SETTINGS

Clinical - Three centres in Wales - North East Wales, North West Wales and Swansea. Trial management - North Wales Organisation for Randomised Trials in Health in Bangor University. Biochemical analysis - University Hospital of Wales, Cardiff. Genetic analysis - University of Liverpool.

PARTICIPANTS

Four hundred and seventy-five adult patients presenting to primary or secondary care with confirmed moderate to severe depression for which they were taking or about to start ADM, and able to consent and complete assessments, but not (1) folate deficient, vitamin B12 deficient, or taking folic acid or anticonvulsants; (2) misusing drugs or alcohol, or suffering from psychosis, bipolar disorder, malignancy or other unstable or terminal illness; (3) (planning to become) pregnant; or (4) participating in other clinical research.

INTERVENTIONS

Once a day for 12 weeks experimental participants added 5 mg of folic acid to their ADM, and control participants added an indistinguishable placebo. All participants followed pragmatic management plans initiated by a trial psychiatrist and maintained by their general medical practitioners.

MAIN OUTCOME MEASURES

Assessed at baseline, and 4, 12 and 25 weeks thereafter, and analysed by 'area under curve' (main); by analysis of covariance at each time point (secondary); and by multi-level repeated measures (sensitivity analysis): Mental health - BDI-II (primary), Clinical Global Impression (CGI), Montgomery-Åsberg Depression Rating Scale (MADRS), UKU side effects scale, and Mini International Neuropsychiatric Interview (MINI) suicidality subscale; General health - UK 12-item Short Form Health Survey (SF-12), European Quality of Life scale - 5 Dimensions (EQ-5D); Biochemistry - serum folate, B12, homocysteine; Adherence - Morisky Questionnaire; Economics - resource use.

RESULTS

Folic acid did not significantly improve any of these measures. For example it gained a mean of just 2.9 quality-adjusted life-days [95% confidence interval (CI) from -12.7 to 7.0 days] and saved a mean of just £48 (95% CI from -£292 to £389). In contrast it significantly reduced mental health scores on the SF-12 by 3.0% (95% CI from -5.2% to -0.8%).

CONCLUSIONS

The FolATED trial generated no evidence that folic acid was clinically effective or cost-effective in augmenting ADM. This negative finding is consistent with improving understanding of the one-carbon folate pathway suggesting that methylfolate is a better candidate for augmenting ADM. Hence the findings of FolATED undermine treatment guidelines that advocate folic acid for treating depression, and suggest future trials of methylfolate to augment ADM.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN37558856.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 18, No. 48. See the HTA programme website for further project information.

Concept mapping One-Carbon Metabolism to model future ontologies for nutrient-gene-phenotype interactions

Advances in the development of bioinformatic tools continue to improve investigators' ability to interrogate, organize, and derive knowledge from large amounts of heterogeneous information. These tools often require advanced technical skills not possessed by life scientists. User-friendly, low-barrier-to-entry methods of visualizing nutrigenomics information are yet to be developed. We utilized concept mapping software from the Institute for Human and Machine Cognition to create a conceptual model of diet and health-related data that provides a foundation for future nutrigenomics ontologies describing published nutrient-gene/polymorphism-phenotype data. In this model, maps containing phenotype, nutrient, gene product, and genetic polymorphism interactions are visualized as triples of two concepts linked together by a linking phrase. These triples, or "knowledge propositions," contextualize aggregated data and information into easy-to-read knowledge maps. Maps of these triples enable visualization of genes spanning the One-Carbon Metabolism (OCM) pathway, their sequence variants, and multiple literature-mined associations including concepts relevant to nutrition, phenotypes, and health. The concept map development process documents the incongruity of information derived from pathway databases versus literature resources. This conceptual model highlights the importance of incorporating information about genes in upstream pathways that provide substrates, as well as downstream pathways that utilize products of the pathway under investigation, in this case OCM. Other genes and their polymorphisms, such as TCN2 and FUT2, although not directly involved in OCM, potentially alter OCM pathway functionality. These upstream gene products regulate substrates such as B12. Constellations of polymorphisms affecting the functionality of genes along OCM, together with substrate and cofactor availability, may impact resultant phenotypes. These conceptual maps provide a foundational framework for development of nutrient-gene/polymorphism-phenotype ontologies and systems visualization.

Genetic variation in prostaglandin synthesis and related pathways, NSAID use and colorectal cancer risk in the Colon Cancer Family Registry

Although use of non-steroidal anti-inflammatory drugs (NSAIDs) generally decreases colorectal cancer (CRC) risk, inherited genetic variation in inflammatory pathways may alter their potential as preventive agents. We investigated whether variation in prostaglandin synthesis and related pathways influences CRC risk in the Colon Cancer Family Registry by examining associations between 192 single nucleotide polymorphisms (SNPs) and two variable nucleotide tandem repeats (VNTRs) within 17 candidate genes and CRC risk. We further assessed interactions between these polymorphisms and NSAID use on CRC risk. Using a case-unaffected-sibling-control design, this study included 1621 primary invasive CRC cases and 2592 sibling controls among Caucasian men and women aged 18-90. After adjustment for multiple comparisons, two intronic SNPs were associated with rectal cancer risk: rs11571364 in ALOX12 [OR(het/hzv) = 1.87, 95% confidence interval (CI) = 1.19-2.95, P = 0.03] and rs45525634 in PTGER2 (OR(het/hzv) = 0.49, 95% CI = 0.29-0.82, P = 0.03). Additionally, there was an interaction between NSAID use and the intronic SNP rs2920421 in ALOX12 on risk of CRC (P = 0.03); among those with heterozygous genotypes, risk was reduced for current NSAID users compared with never or former users (OR(het) = 0.60, 95% CI = 0.45-0.80), though not among those with homozygous wild-type or variant genotypes. The results of this study suggest that genetic variation in ALOX12 and PTGER2 may affect the risk of rectal cancer. In addition, this study suggests plausible interactions between NSAID use and variants in ALOX12 on CRC risk. These results may aid in the development of genetically targeted cancer prevention strategies with NSAIDs.

Association of dietary and supplemental folate intake and polymorphisms in three FOCM pathway genes with colorectal cancer in a population-based case-control study

Previous research has shown that greater intakes of dietary folate are associated with reduced risk for colorectal cancer (CRC) and that single nucleotide polymorphisms (SNPs) in genes involved in folate-mediated one-carbon metabolism (FOCM) also may be involved in altering CRC risk. The objective of this study was to evaluate the role of folate intake (and intakes of related dietary components such as methionine), 35 SNPs in three FOCM pathway genes (MTHFD1, MTHFR, and TYMS), and their interactions on CRC risk in a population-based case-control study in Pennsylvania (686 cases, 740 controls). Diet and supplement use was assessed for the year before diagnosis or interview for cases and controls, respectively, with a modified Diet History Questionnaire from the National Cancer Institute. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using unconditional logistic regression. Using a dominant model for the variant allele, several SNPs were significantly associated with CRC including MTHFD1 rs8003379 (OR = 1.65; 95% CI = 1.00-2.73) and rs17824591 (OR = 1.98; 95% CI = 1.14-3.41) and the TYMS rs2853533 SNP (OR = 1.38; 95% CI = 1.05-1.80). Using a nondominant model, the AA genotype for MTHFR rs1476413 exhibited a marginally significant (OR = 1.56; 95% CI = 1.00-2.44) association with CRC. Two TYMS SNPs (rs16948305 and rs495139) exhibited significant (P = 0.024 and P = 0.040, respectively) gene-diet interactions with folate intake. One MTHFD1 (P = 0.019) and one MTHFR (P = 0.042) SNP exhibited gene-diet interactions with methionine intake. These findings suggest that allelic variants in genes involved in FOCM interact with dietary factors including folate and methionine to modify risk for CRC.

Lack of association between methionine synthase A2756G polymorphism and digestive system cancer risk: evidence from 3,9327 subjects

Background

Polymorphisms in genes involved in the metabolism of folate and methyl groups have been implicated with risk of digestive system cancer. Methionine synthase (MTR) plays a central role in folate metabolism, thereby affecting DNA methylation. The association between A2756G polymorphism (rs1805087) in MTR and digestive system cancer susceptibility was inconsistent in previous studies. To investigate this inconsistency, we performed this meta-analysis.

Methods

Databases including Pubmed, EMBASE, ISI Web of Science and China National Knowledge Infrastructure (CNKI) were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. Potential sources of heterogeneity were also assessed by subgroup analysis and meta-regression.

Results

A total of 29 articles with 15,368 patients and 23,959 controls were included. We found no association between MTR A2756G polymorphism and digestive system cancer in overall population (G allele: OR = 1.03, 95% CI = 0.98–1.09, P = 0.25; dominant model: OR = 1.03, 95% CI = 0.97–1.10, P = 0.33; recessive model: OR = 1.02, 95% CI = 0.89–1.17, P = 0.79). In the stratified analyses according to cancer type, sample size and genotyping method, no evidence of any gene-disease association was obtained in almost all genetic models. However, marginal significant associations were found for East Asians and hospital-based studies.

Conclusions

This meta-analysis suggests that there is no significant association between the MTR A2756G polymorphism and digestive system cancer risk.

Methionine synthase A2756G polymorphism and risk of colorectal adenoma and cancer: evidence based on 27 studies

Methionine synthase (MTR), which plays a central role in maintaining adequate intracellular folate, methionine and normal homocysteine concentrations, was thought to be involved in the development of colorectal cancer (CRC) and colorectal adenoma (CRA) by affecting DNA methylation. However, studies on the association between MTR A2756G polymorphism and CRC/CRA remain conflicting. We conducted a meta-analysis of 27 studies, including 13465 cases and 20430 controls for CRC, and 4844 cases and 11743 controls for CRA. Potential sources of heterogeneity and publication bias were also systematically explored. Overall, the summary odds ratio of G variant for CRC was 1.03 (95% CI: 0.96-1.09) and 1.05 (95% CI: 0.99-1.12) for CRA. No significant results were observed in heterozygous and homozygous when compared with wild genotype for these polymorphisms. In the stratified analyses according to ethnicity, source of controls, sample size, sex, and tumor site, no evidence of any gene-disease association was obtained. Results from the meta-analysis of four studies on MTR stratified according to smoking and alcohol drinking status showed an increased CRC risk in heavy smokers (OR = 2.06, 95% CI: 1.32-3.20) and heavy drinkers (OR = 2.00, 95% CI: 1.28-3.09) for G allele carriers. This meta-analysis suggests that the MTR A2756G polymorphism is not associated with CRC/CRA susceptibility and that gene-environment interaction may exist.

Association between CASR polymorphisms, calcium intake, and colorectal cancer risk

Aim

The current study aimed to assess the effect of dietary calcium intake and possible interactions with calcium-sensing receptor (CASR) gene polymorphisms on colorectal cancer risk.

Methods

A total of 420 colorectal cancer cases and 815 controls were included in the analysis. Calcium intake was investigated using a 103 item semi-quantitative food frequency questionnaire, and four single nucleotide polymorphisms (SNPs) within the CASR, rs10934578, rs12485716, rs2270916, and rs4678174, were evaluated.

Results

No SNPs were associated with colorectal cancer risk after adjusting for covariates. Overall, no significant effect modification by CASR polymorphisms on the association between calcium intake and colorectal cancer risk were detected. However, all 4 of the polymorphisms within the CASR showed significantly higher odds ratios for association with colorectal cancer risk in the low-calcium-intake group compared to the high-calcium-intake group. In the case of rs2270916, individuals with the CC genotype and low calcium intake showed an increased colorectal cancer risk compared to their counterparts with the TT genotype and high calcium intake (OR = 2.11, 95% CI = 1.27–3.51).

Conclusions

Subjects with lower calcium intake exhibited a higher colorectal cancer risk compared with subjects with the same genotype who had higher calcium intake. Our results suggest that individuals who have low dietary calcium intake should be aware of their increased colorectal cancer risk and prevention strategies.

Folate-genetics and colorectal neoplasia: what we know and need to know next

SCOPE

The metabolism of folate involves a complex network of polymorphic enzymes that may explain a proportion of the risk associated with colorectal neoplasia. Over 60 observational studies primarily in non-Hispanic White populations have been conducted on selected genetic variants in specific genes, MTHFR, MTR, MTRR, CBS, TCNII, RFC, GCPII, SHMT, TYMS, and MTHFD1, including five meta-analyses on MTHFR 677C>T (rs1801133) and MTHFR 1298C>T (rs1801131); two meta-analyses on MTR-2756A>C (rs1805087); and one for MTRR 66A>G (rs1801394).

METHODS AND RESULTS

This systematic review synthesizes these data, highlighting the consistent inverse association between MTHFR 677TT genotype and risk of colorectal cancer (CRC) and its null association with adenoma risk. Results for other variants varied across individual studies; in our meta-analyses we observed some evidence for SHMT 1420C>T (rs1979277) ((odds ratio) OR = 0.85; 95% confidence interval (CI) = 0.73-1.00 for TT v. CC) and TYMS 5' 28 bp repeat (rs34743033) and CRC risk (OR = 0.84; 95% CI = 0.75-0.94 for 2R/3R v. 3R/3R and OR = 0.82; 95% CI = 0.69-0.98 for 2R/2R v. 3R/3R).

CONCLUSION

To gain further insight into the role of folate variants in colorectal neoplasia will require incorporating measures of the metabolites, including B-vitamin cofactors, homocysteine and S-adenosylmethionine, and innovative statistical methods to better approximate the folate one-carbon metabolism pathway.

IκBKβ and NFκB1, NSAID use and risk of colorectal cancer in the Colon Cancer Family Registry

The NFκB-signaling pathway regulates cell proliferation and inflammation. Activation of the pathway is implicated in the etiology of colorectal cancer (CRC). NSAIDs may reduce CRC risk partially through a nuclear factor-kappa B (NFκB)-dependent pathway. In this study, we investigated associations between 34 NFκB1 and 8 IκBKβ tagSNPs and CRC risk and examined interactions with non-steroidal anti-inflammatory drug (NSAID) use. Using conditional logistic regression, we investigated these associations among 1584 incident CRC cases and 2516 sibling controls from the Colon Cancer Family Registry. Three IκBKβ SNPs were associated with a statistically significant lower colorectal or colon cancer risk: rs9694958 (A>G intron 5) (colorectal: OR(hzv) = 0.26(0.07-0.99), P(trend) = 0.048, P(adj) = 0.25), rs10958713 (A>C intron 19) (colon: OR(hzv) = 0.62(0.42-0.92), P(trend) = 0.005, P(adj) = 0.03) and rs5029748 (C>A intron 2) (colon: OR(het) = 0.72(0.56-0.91), P(trend) = 0.01, P(adj) = 0.08). We replicated trends associated with NFκB1 and IκBKβ variants identified in a previous study (rs4648110 (T>A intron 22), rs13117745 (G>A intron 5) and rs3747811 (T>A intron 1)). IκBKβ's rs6474387 (C>T intron 20) and rs11986055 (A>C intron 2) showed substantially lower colon cancer risk among current NSAID users (P(interaction) = 0.01 and P(interaction) = 0.045, respectively), whereas NFκB1's rs230490 (G>A 5' (outside UTR)) and rs997476 (C>A 3' (outside UTR)) showed higher CRC risk among current NSAID users (P(interaction) = 0.01 and P(interaction) = 0.03, respectively). These findings suggest that variants in NFκB1 and IκBKβ are associated with CRC risk and NSAIDs may function partially through an NFκB-dependent pathway. The SNPs identified here should be considered for future functional studies and may be useful in designing a pharmacogenetic approach to preventive NSAID use.

A candidate gene study of one-carbon metabolism pathway genes and colorectal cancer risk

The risk of colorectal cancer (CRC) may be influenced by aberrant DNA methylation and altered nucleotide synthesis and repair, possibly caused by impaired dietary folate intake as well as by polymorphic variants in one-carbon metabolism genes. A case-control study using seventy-one CRC patients and eighty unrelated healthy controls was carried out to assess the genetic association of fifteen SNP and one insertion in nine genes belonging to the folate pathway. Polymorphism selection was based on literature data, and included those which have a known or suspected functional impact on cancer and missense polymorphisms that are most likely to alter protein function. Genotyping was performed by real-time PCR and PCR followed by restriction analysis. The likelihood ratio statistic indicated that most of the polymorphisms were not associated with the risk of CRC. However, an increased risk of CRC was observed for two variant alleles of SNP mapping on the transcobalamin 2 gene (TCN2): C776G (rs1801198) and c.1026-394T>G (rs7286680). Considering the crucial biological function played by one-carbon metabolism genes, further investigations with larger cohorts of CRC patients are needed in order to confirm our preliminary results. These preliminary results indicate that TCN2 polymorphisms can be a susceptibility factor for CRC.

Regular Multivitamin Supplement Use, Single Nucleotide Polymorphisms in ATIC, SHMT2, and SLC46A1, and Risk of Ovarian Carcinoma

ATIC, SHMT2, and SLC46A1 have essential roles in one-carbon (1-C) transfer. The authors examined whether associations between ovarian carcinoma and 15 variants in these genes are modified by regular multivitamin use, a source of 1-C donors, among Caucasian participants from two US case–control studies. Using a phased study design, variant-by-multivitamin interactions were tested, and associations between variants and ovarian carcinoma were reported stratified by multivitamin supplement use. Per-allele risk associations were modified by multivitamin use at six variants among 655 cases and 920 controls (Phase 1). In a larger sample of 968 cases and 1,265 controls (Phases 1 and 2), interactions were significant (P ≤ 0.03) for two variants, particularly among regular multivitamin users: ATIC rs7586969 [odds ratio (OR) = 0.7, 95% confidence interval (CI) = 0.6–0.9] and ATIC rs16853834 (OR = 1.5, 95% CI = 1.1–2.0). The two ATIC single nucleotide polymorphisms (SNPs) did not share the same haplotype; however, the haplotypes they comprised mirrored their SNP risk associations among regular multivitamin supplement users. A multi-variant analysis was also performed by comparing the observed likelihood ratio test statistic from adjusted models with and without the two ATIC variant-by-multivitamin interaction terms with a null distribution of test statistics generated by permuting case status 10,000 times. The corresponding observed P value of 0.001 was more extreme than the permutation-derived P value of 0.009, suggesting rejection of the null hypothesis of no association. In summary, there is little statistical evidence that the 15 variants are independently associated with risk of ovarian carcinoma. However, the statistical interaction of ATIC variants with regular multivitamin intake, when evaluated at both the SNP and gene level, may support these findings as relevant to ovarian health and disease processes.

Epigenetics of colorectal cancer

Colorectal cancer (CRC) develops through a multistep process that results from the progressive accumulation of mutations and epigenetic alterations in tumor suppressor genes and oncogenes. Epigenetic modifications, that have a fundamental role in the regulation of gene expression, involve DNA methylation, specific histone modifications and non-coding RNAs (ncRNAs) interventions. Many genes have been until now studied to detect their methylation status during CRC carcinogenesis; and the functions of many of these genes in cancer initiation and progression are being clarified. Less is known about the patterns of histone modification alterations in CRC. Epigenetic deregulation of the ncRNAs or the genes involved in their biogenesis have been described in tumor progression and some examples of dysregulated microRNA were found also in CRC cells. Diet has an important role in the etiology of colon cancer. Folate is involved via 5-methyltetrahydrofolate in the conversion of homocysteine to methionine, which is then used to form the main DNA methylating agent S-adenosylmethionine. However, the role of folate in protecting from or in promoting CRC, depending on conditions, is still debated. The study of epigenetic marks to better characterize CRC and to identify new tools for diagnosis and prognosis as well as for therapeutic interventions is extremely promising.

Epigenetic epidemiology in psychiatry: A translational neuroscience perspective

Accumulating evidence from the field of neuroscience indicates a crucial role for epigenetic regulation of gene expression in development and aging of nervous system and suggests that aberrations in the epigenetic machinery are involved in the etiology of psychiatric disorders. Epidemiologic evidence on epigenetics in psychiatry, however, is currently very sparsely available, but is consistent with a mediating role for epigenetic mechanisms in bringing together inherited and acquired risk factors into a neurodevelopmental etiological model of psychiatric disorders. Here, we review evidence from the epidemiological and neuroscience literature, and aim to converge the evidence into an etiological model of psychiatric disorders that encompasses environmental, genetic and epigenetic contributions. Given the dynamic nature of the epigenetic machinery and the potential reversibility of epigenetic modifications, future well-designed interdisciplinary and translational studies will be of key importance in order to identify new targets for prevention and therapeutic strategies.

Genetic variation in inflammatory pathways is related to colorectal cancer survival

PURPOSE

Prognosis of patients with colorectal cancer (CRC) is associated with systemic inflammation, and anti-inflammatory drugs can reduce both CRC incidence and mortality. Genetic variation in proinflammatory pathways can affect an individual's CRC risk. However, few studies have investigated the prognostic importance of this genetic variation in CRC patients.

EXPERIMENTAL DESIGN

We investigated the association between CRC survival and genetic variation in proinflammatory pathways among patients from the Puget Sound Surveillance Epidemiology and End Results registry. Single-nucleotide polymorphisms were genotyped in five genes (PTGS-1, PTGS-2, MRP4, NFκB, and IκBKβ). Vital status was ascertained through linkage to the National Death Index. Cox proportional hazards regression was used to calculate HRs and 95% confidence intervals (CI). The false discovery rate method of Benjamini and Hochberg was applied to address multiple testing.

RESULTS

Four PTGS-1 variants were associated with CRC survival. One, G>A intron 9 (rs1213266), was associated with approximately 50% lower CRC mortality (HR(AA/AG vs. GG) = 0.48; 95% CI, 0.25-0.93). Three variants, including L237M, resulted in significantly elevated CRC mortality risk, with HRs ranging from approximately 1.5 to 2.0. Two variants in IκBKβ, including R526Q, were significantly associated with CRC survival. Correction for multiple testing indicated that variants in both PTGS-1 and IκBKβ are reproducibly associated with CRC survival.

CONCLUSION

Our findings suggest that genetic variation in proinflammatory pathways may be important for CRC prognosis. This investigation represents one of the first descriptions of the relationship between inherited polymorphisms and mortality in CRC patients and provides a starting point for further research.

Meta-analysis of MTHFR gene variants in schizophrenia, bipolar disorder and unipolar depressive disorder: evidence for a common genetic vulnerability?

Past analyses examining the relationship between genetic variation in the 5, 10-methylenetetrahydrofolate reductase (MTHFR) gene and psychiatric disorders have provided mixed and largely inconclusive findings. MTHFR is involved in the one-carbon metabolic pathway which is essential for DNA biosynthesis and the epigenetic process of DNA methylation. We conducted a meta-analysis of all published case-control studies investigating associations between two common MTHFR single nucleotide polymorphisms (SNPs), MTHFR C677T (sample size 29,502) and A1298C (sample size 7934), and the major psychiatric disorders (i) schizophrenia (SZ), (ii) bipolar disorder (BPD), and (iii) unipolar depressive disorder (UDD). In order to examine possible shared genetic vulnerability, we also tested for associations between MTHFR and all of these major psychiatric disorders (SZ, BPD and UDD) combined. MTHFR C677T was significantly associated with all of the combined psychiatric disorders (SZ, BPD and UDD); random effects odds ratio (OR)=1.26 for TT versus CC genotype carriers; confidence interval (CI) 1.09-1.46); meta-regression did not suggest moderating effects of psychiatric diagnosis, sex, ethnic group or year of publication. Although MTHFR A1298C was not significantly associated with the combination of major psychiatric disorders, nor with SZ, there was evidence for diagnostic moderation indicating a significant association with BPD (random effects OR=2.03 for AA versus CC genotype carriers, CI: 1.07-3.86). Meta-analysis on UDD was not possible due to the small number of studies available. This study provides evidence for shared genetic vulnerability for SZ, BPD and UDD mediated by MTHFR 677TT genotype, which is in line with epigenetic involvement in the pathophysiology of these psychiatric disorders.

Dihydrofolate reductase gene variations in susceptibility to disease and treatment outcomes

Dihydrofolate reductase (DHFR) catalyzes the reduction of dihydrofolate to tetrahydrofolate (THF). THF is needed for the action of folate-dependent enzymes and is thus essential for DNA synthesis and methylation. The importance of this reaction is demonstrated by the effectiveness of antifolate medications used to treat cancer by inhibiting DHFR, thereby depleting THF and slowing DNA synthesis and cell proliferation. Due to the pivotal role that DHFR plays in folate metabolism and cancer treatment, changes in the level of DHFR expression can affect susceptibility to a variety of diseases dependent on folate status such as spina bifida and cancer. Likewise, variability in DHFR expression can affect sensitivity to anti-cancer drugs such as the folate antagonist methotrexate. Alterations in DHFR expression can be due to polymorphisms in the DHFR gene. Several variations have recently been described in DHFR, including promoter polymorphisms, the 19-bp deletion allele and variations in 3’UTR. These polymorphisms seem to be functional, affecting mRNA levels through various interesting mechanisms, including regulation through RNA interference. Several groups have assessed the association of these polymorphisms with folate levels, risk of cancer and spina bifida as well as the outcome of diseases treated with MTX. The latter may lead to different treatment schedules, improving treatment efficacy and/or allowing for a reduction in drug side effects. This review will summarize present knowledge regarding the predictive potential of DHFR polymorphisms in disease and treatment.

Influence of polymorphisms in MTHFR 677 C→T, TYMS 3R→2R and MTR 2756 A→G on NSCLC risk and response to platinum-based chemotherapy in advanced NSCLC

AIMS

Genetic factors may contribute to individual differences in cancer susceptibility, drug efficacy and toxicity. This study was designed to investigate the effects of the polymorphisms of methylenetetrahydrofolate reductase 677 C→T (MTHFR 677 C→T), thymidylate synthase (TYMS 3R→2R),and methionine synthase 2756 A→G (MTR 2756 A→G) on the risk of lung cancer and response to platinum-based chemotherapy in advanced non-small-cell lung cancer (NSCLC).

MATERIALS & METHODS

We conducted a case-control study involving 438 NSCLC cases (including 101 follow-up cases) and 641 healthy controls in North China.

RESULTS & CONCLUSION

Using a genetic model analysis, the polymorphism MTHFR 677 C→T showed a significantly increased risk for NSCLC in women but not in men, which was observed in the codominant model (CT vs CC adjusted odds ratio [OR] = 2.46; 95% confidence interval [CI]: 1.37-4.42; p = 0.003; TT vs CC adjusted OR: 2.04; 95% CI: 1.09-3.81; p = 0.03) and the dominant model (CT + TT vs CC adjusted OR: 2.30; 95% CI: 1.31-4.05; p = 0.004). In addition, we found that patients with the MTHFR 677 TT genotype showed a better response to platinum-based chemotherapy in the recessive model (TT vs CT + CC adjusted OR: 0.24; 95% CI: 0.09-0.68; p = 0.007), the generalized OR was 0.44 (0.22-0.88; p = 0.04). There were no significant associations of the polymorphisms of TYMS 3R→2R or MTR 2756 A→G with the risk of NSCLC or response to platinum-based chemotherapy in advanced NSCLC in any genetic model. Our results suggest that genetic polymorphisms of MTHFR 677 C→T may contribute to NSCLC development in Chinese women and could also influence treatment response for advanced NSCLC patients with platinum-based chemotherapy. Further studies with larger sample sizes are required to validate this association.

Nutrigenomic analysis of C677T mutation of MTHFR gene in Slovak population

Total of 124 individuals originated from Slovak Republic has been nutrignomically analysed. Analysis was focused to mutation C677T of MTHFR gene detection and analysis of mutant genotypes frequency. Observed frequency of allele 677C was 0.6998 and allelic frequency of mutant variant 677T was 0.3992. Genotype frequency of mutant heterozygotes with 71% activity of MTHFR enzyme was 0,391 and mutant homozygotes with 33% MTHFR enzyme activity was 0.153. Result shows 64% of Slovak has decreased activity of enzyme MTHFR, and 14.3% of Slovak has predisposition to cancer, cardio vascular diseases, loss of fertility and many others complications according to improper nutrition, low folic acid and B12 vitamin intake. 

Molecular pathological epidemiology of colorectal neoplasia: an emerging transdisciplinary and interdisciplinary field

Colorectal cancer is a complex disease resulting from somatic genetic and epigenetic alterations, including locus-specific CpG island methylation and global DNA or LINE-1 hypomethylation. Global molecular characteristics such as microsatellite instability (MSI), CpG island methylator phenotype (CIMP), global DNA hypomethylation, and chromosomal instability cause alterations of gene function on a genome-wide scale. Activation of oncogenes including KRAS, BRAF and PIK3CA affects intracellular signalling pathways and has been associated with CIMP and MSI. Traditional epidemiology research has investigated various factors in relation to an overall risk of colon and/or rectal cancer. However, colorectal cancers comprise a heterogeneous group of diseases with different sets of genetic and epigenetic alterations. To better understand how a particular exposure influences the carcinogenic and pathologic process, somatic molecular changes and tumour biomarkers have been studied in relation to the exposure of interest. Moreover, an investigation of interactive effects of tumour molecular changes and the exposures of interest on tumour behaviour (prognosis or clinical outcome) can lead to a better understanding of tumour molecular changes, which may be prognostic or predictive tissue biomarkers. These new research efforts represent 'molecular pathologic epidemiology', which is a multidisciplinary field of investigations of the inter-relationship between exogenous and endogenous (eg, genetic) factors, tumoural molecular signatures and tumour progression. Furthermore, integrating genome-wide association studies (GWAS) with molecular pathological investigation is a promising area (GWAS-MPE approach). Examining the relationship between susceptibility alleles identified by GWAS and specific molecular alterations can help elucidate the function of these alleles and provide insights into whether susceptibility alleles are truly causal. Although there are challenges, molecular pathological epidemiology has unique strengths, and can provide insights into the pathogenic process and help optimise personalised prevention and therapy. In this review, we overview this relatively new field of research and discuss measures to overcome challenges and move this field forward.

Candidate pathway polymorphisms in one-carbon metabolism and risk of rectal tumor mutations

We examined candidate polymorphisms in genes involved in the folate-mediated, one-carbon metabolism pathway, DNMT1 1311V, MTHFD1 R134K and R653Q, MTHFR R594Q, MTR D919G, MTRR H595Y and I22M, SHMT1 L474F, SLC19A1 H27R, and TDG G199S, and associations with rectal tumor characteristics. We hypothesized that these candidate genes would influence CpG Island Methylator Phenotype and potentially KRAS2 or TP53 tumors. Data from a population-based study of 747 rectal cases (593 with tumor markers) and 956 controls were evaluated using generalized estimating equations. We observed an increased risk of TP53 tumor mutations in homozygous carriers of the MTHFD1 134K allele (0R=2.0, 95%CI 1.2-3.1, P- trend=0.02). In the presence of low folate intake, the R134K variant was associated with increased risk of CIMP+ tumors (OR=2.8, 95%CI 1.04-7.7). The MTRR I22M variant genotype was associated with a modest increased risk of TP53 mutations (OR=1.7, 95%CI 1.2-2.5, P-trend=0.001). Our findings offer limited support that polymorphisms in one-carbon metabolism genes influence rectal tumor phenotype, and that folate may interact with MTHFD1 to alter CIMP+ risk.

Prevention of mutation, cancer, and other age-associated diseases by optimizing micronutrient intake

I review three of our research efforts which suggest that optimizing micronutrient intake will in turn optimize metabolism, resulting in decreased DNA damage and less cancer as well as other degenerative diseases of aging. (1) Research on delay of the mitochondrial decay of aging, including release of mutagenic oxidants, by supplementing rats with lipoic acid and acetyl carnitine. (2) The triage theory, which posits that modest micronutrient deficiencies (common in much of the population) accelerate molecular aging, including DNA damage, mitochondrial decay, and supportive evidence for the theory, including an in-depth analysis of vitamin K that suggests the importance of achieving optimal micronutrient intake for longevity. (3) The finding that decreased enzyme binding constants (increased Km) for coenzymes (or substrates) can result from protein deformation and loss of function due to an age-related decline in membrane fluidity, or to polymorphisms or mutation. The loss of enzyme function can be compensated by a high dietary intake of any of the B vitamins, which increases the level of the vitamin-derived coenzyme. This dietary remediation illustrates the importance of understanding the effects of age and polymorphisms on optimal micronutrient requirements. Optimizing micronutrient intake could have a major effect on the prevention of cancer and other degenerative diseases of aging.