Alcohol, one-carbon metabolism, and colorectal cancer: recent insights from molecular studies

The global, regional, and national alcohol-related colorectal cancer burden and forecasted trends: results from the global burden of disease study 2021

Background

The mortality of colorectal cancer (CRC) is increasing year by year and poses a significant global health burden. Many studies have demonstrated that alcohol consumption is an important risk factor for CRC and is closely associated with malignant metastasis in CRC patients, which in turn leads to a poor prognosis.

Methods

This study aimed to quantify the global, regional, and national burden of alcohol-related CRC between 1990 and 2021. First, numbers and age-standardized rates of deaths and disability-adjusted life years (DALYs) for alcohol-related CRC in 2021 were analyzed at different levels. Temporal trends in the burden of disease from 1990 to 2021 were analyzed through linear regression models. Finally, both Age-Period-Cohort (APC) models and Bayesian Age-Period-Cohort (BAPC) models were utilized to project the future burden of the disease for 2022-2046.

Results

The global burden of disease for alcohol-related CRC is higher in 2021 compared to 1990. Male and older age groups are at high risk. Disease burden varies very much between Sociodemographic Index (SDI) regions, Global Burden of Disease (GBD) regions and countries. From 1990 to 2021, the number of cases increased, but the Age-Standardized Rate (ASR) decreased. The trends in disease burden predicted by the two models for 2022-2046 were not consistent.

Conclusion

This study describes the burden of disease in alcohol-related CRC and emphasizes that alcohol is a non-negligible risk factor for CRC. In order to mitigate harm, we need to strengthen disease surveillance, early prevention, timely detection, and improved treatment measures, with different approaches and responses for different regions.

Genetics, diet, microbiota, and metabolome: partners in crime for colon carcinogenesis

Colorectal cancer (CRC) ranks among the most prevalent malignant tumors worldwide, with a multifactorial etiology encompassing genetic, environmental, and life-style factors, as well as the intestinal microbiota and its metabolome. These risk factors often work together in specific groups of patients, influencing how CRC develops and progresses. Importantly, alterations in the gut microbiota act as a critical nexus in this interplay, significantly affecting susceptibility to CRC. This review highlights recent insights into unmodifiable and modifiable risk factors for CRC and how they might interact with the gut microbiota and its metabolome. Understanding the mechanisms of these interactions will help us develop targeted, precision-medicine strategies that can adjust the composition of the gut microbiota to meet individual health needs, preventing or treating CRC more effectively.

Microbiota and other detrimental metabolites in colorectal cancer

Increasing scientific evidence demonstrates that gut microbiota plays an essential role in the onset and development of Colorectal cancer (CRC). However, the mechanisms by which these microorganisms contribute to cancer development are complex and far from completely clarified. Specifically, the impact of gut microbiota-derived metabolites on CRC is undeniable, exerting both protective and detrimental effects. This paper examines the effects and mechanisms by which important bacterial metabolites exert detrimental effects associated with increased risk of CRC. Metabolites considered include heterocyclic amines and polycyclic aromatic hydrocarbons, heme iron, secondary bile acids, ethanol, and aromatic amines. It is necessary to delve deeper into the mechanisms of action of these metabolites in CRC and identify the microbiota members involved in their production. Furthermore, since diet is the main factor capable of modifying the intestinal microbiota, conducting studies that include detailed descriptions of dietary interventions is crucial. All this knowledge is essential for developing precision nutrition strategies to optimise a protective intestinal microbiota against CRC.

Effects of moderate ethanol exposure on risk factors for cardiovascular disease and colorectal cancer in adult Wistar rats

While past studies have provided evidence linking excessive alcohol consumption to increased risk for cardiovascular diseases (CVDs) and colorectal cancer (CRC), existing data on the effects of moderate alcohol use on these conditions have produced mixed results. The purpose of this study was to investigate the effects of moderate alcohol consumption on risk factors associated with the development of CVDs and CRC in adult rats. Twenty-four, 14-month-old, non-deprived male Wistar rats were randomly assigned to either an ethanol group, which consisted of voluntary access to a 20% (v/v) ethanol solution on alternate days, or a water control group (n = 12/group) for 13 weeks. Blood samples were collected to analyze levels of albumin, glucose, adiponectin, lipids, oxidized low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), apolipoprotein A1 (apoA1), C-reactive protein (CRP), high-mobility group box 1 protein (HMGB-1), tumor necrosis factor-alpha (TNF-α), thyroxine, thyroid-stimulating hormone, 8-oxo-2'-deoxyguanosine (8-oxo-dG), liver function enzymes, and antioxidant capacity. Colonic gene expression related to colon carcinogenesis was also assessed. Ethanol-treated rats were found to have significantly higher HDL-C and apoA1 levels compared to controls. Moderate alcohol consumption led to significantly lower CRP levels and a trend for decrease in HMGB-1, TNF-α, and 8-oxo-dG levels. In the ethanol-exposed group, colonic gene expression of superoxide dismutase was upregulated while aldehyde dehydrogenase 2 showed a trend for increase compared to the control group. These results indicate that adopting a moderate approach to alcohol consumption could potentially improve health biomarkers related to CVD and CRC by increasing HDL-C levels and antioxidant activity and reducing DNA damage and inflammatory activity.

The Importance of Nutrigenetics and Microbiota in Personalized Medicine: From Phenotype to Genotype

Background After the completion of the Human Genome Project in 2003, the impact of genetic variations among people on human health was better understood. Precision medicine, also called 4P (Predictive, Preventive, Personalized, Participatory) medicine, is used to determine personal health risks, prevent, diagnose, and treat chronic diseases, and aims to identify the phenotypic, genotypic, and environmental factors that affect individual health risks instead of applying the same approach to everyone. Methods The study was conducted with 24 patients aged between 7 and 57. The patient group was selected from individuals who had undergone genetic and microbiota testing at Epigenetic Coaching Company. The patients' age, gender, and health status were documented. Genomic analysis of buccal samples was subsequently conducted using a custom Infinium HTS iSelect microarray on an Illumina iScan instrument, and microbiota metagenome analysis was performed using an Illumina NextSeq 500 platform. This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of Biruni University Molecular Biology and Genetics Ethics Committee, with the decision number 2023/78-03. Results The genotypes of 19 cases carrying genetic variants involved in the metabolism of Vitamin D, Folate, B12, and Choline were analyzed. Eight of the cases were included in our study as autism patients, eight as allergy patients, and three as autoimmune thyroiditis patients. The Vitamin D receptor (VDR) genetic variants and microbiota diversity (using the Firmicutes/Bacteroides ratio, an indicator of dysbiosis) of 11 cases (9 allergy and two autism patients) participating in the study were evaluated together. Conclusions Translating nutrigenetic and nutrigenomic research into multidisciplinary clinical practice is the most challenging aspect. It is now evident that integrating data regarding phenotype and genotype, and using nutrition, lifestyle, and supplements tailored to an individual's genetics can increase clinical success. Importantly, if we wish to adopt an epigenomic approach, we must incorporate analyses of nutrigenetics, microbiota, and personalized risk based on test results.

Environment factors, DNA methylation, and cancer

Today, the rapid development of science and technology and the rapid change in economy and society are changing the way of life of human beings and affecting the natural, living, working, and internal environment on which human beings depend. At the same time, the global incidence of cancer has increased significantly yearly, and cancer has become the number one killer that threatens human health. Studies have shown that diet, living habits, residential environment, mental and psychological factors, intestinal flora, genetics, social factors, and viral and non-viral infections are closely related to human cancer. However, the molecular mechanisms of the environment and cancer development remain to be further explored. In recent years, DNA methylation has become a key hub and bridge for environmental and cancer research. Some environmental factors can alter the hyper/hypomethylation of human cancer suppressor gene promoters, proto-oncogene promoters, and the whole genome, causing low/high expression or gene mutation of related genes, thereby exerting oncogenic or anticancer effects. It is expected to develop early warning markers of cancer environment based on DNA methylation, thereby providing new methods for early detection of cancers, diagnosis, and targeted therapy. This review systematically expounds on the internal mechanism of environmental factors affecting cancer by changing DNA methylation, aiming to help establish the concept of cancer prevention and improve people's health.

Food Intake and Colorectal Cancer

Colorectal cancer (CRC) accounts for considerable mortalities worldwide. Several modifiable risk factors, including a high intake of certain foods and beverages can cause CRC. This review summarized the latest findings on the intake of various foods, nutrients, ingredients, and beverages on CRC development, with the objective of classifying them as a risk or protective factor. High-risk food items include red meat, processed meat, eggs, high alcohol consumption, sugar-sweetened beverages, and chocolate candy. Food items that are protective include milk, cheese and other dairy products, fruits, vegetables (particularly cruciferous), whole grains, legumes (particularly soy beans), fish, tea (particularly green tea), coffee (particularly among Asians), chocolate, and moderate alcohol consumption (particularly wine). High-risk nutrients/ingredients include dietary fat from animal sources and industrial trans-fatty acids (semisolid/solid hydrogenated oils), synthetic food coloring, monosodium glutamate, titanium dioxide, and high-fructose corn sirup. Nutrients/ingredients that are protective include dietary fiber (particularly from cereals), fatty acids (medium-chain and odd-chain saturated fatty acids and highly unsaturated fatty acids, including omega-3 polyunsaturated fatty acids), calcium, polyphenols, curcumin, selenium, zinc, magnesium, and vitamins A, C, D, E, and B (particularly B6, B9, and B2). A combination of micronutrients and multi-vitamins also appears to be beneficial in reducing recurrent adenoma incidence.

Influence of methyl donor nutrients as epigenetic regulators in colorectal cancer: A systematic review of observational studies

BACKGROUND

Dietary methyl donors might influence DNA methylation during carcinogenesis of colorectal cancer (CRC). However, whether the influence of methyl donor intake is modified by polymorphisms in such epigenetic regulators is still unclear.

AIM

To improve the current understanding of the molecular basis of CRC.

METHODS

A literature search in the Medline database, Reference Citation Analysis (https://www.referencecitationanalysis.com/), and manual reference screening were performed to identify observational studies published from inception to May 2022.

RESULTS

A total of fourteen case-control studies and five cohort studies were identified. These studies included information on dietary methyl donors, dietary components that potentially modulate the bioavailability of methyl groups, genetic variants of methyl metabolizing enzymes, and/or markers of CpG island methylator phenotype and/or microsatellite instability, and their possible interactions on CRC risk.

CONCLUSION

Several studies have suggested interactions between methylenetetrahydrofolate reductase polymorphisms, methyl donor nutrients (such as folate) and alcohol on CRC risk. Moreover, vitamin B₆, niacin, and alcohol may affect CRC risk through not only genetic but also epigenetic regulation. Identification of specific mechanisms in these interactions associated with CRC may assist in developing targeted prevention strategies for individuals at the highest risk of developing CRC.

Gut microbiota-derived metabolites in CRC progression and causation

BACKGROUND

Based on recent research reports, dysbiosis and improper concentrations of microbial metabolites in the gut may result into the carcinogenesis of colorectal cancer. Recent advancement also highlights the involvement of bacteria and their secreted metabolites in the cancer causation. Gut microbial metabolites are functional output of the host-microbiota interactions and produced by anaerobic fermentation of food components in the diet. They contribute to influence variety of biological mechanisms including inflammation, cell signaling, cell-cycle disruption which are majorly disrupted in carcinogenic activities.

PURPOSE

In this review, we intend to discuss recent updates and possible molecular mechanisms to provide the role of bacterial metabolites, gut bacteria and diet in the colorectal carcinogenesis. Recent evidences have proposed the role of bacteria, such as Fusobacterium nucleaturm, Streptococcus bovis, Helicobacter pylori, Bacteroides fragilis and Clostridium septicum, in the carcinogenesis of CRC. Metagenomic study confirmed that these bacteria are in increased abundance in CRC patient as compared to healthy individuals and can cause inflammation and DNA damage which can lead to development of cancer. These bacteria produce metabolites, such as secondary bile salts from primary bile salts, hydrogen sulfide, trimethylamine-N-oxide (TMAO), which are likely to promote inflammation and subsequently cancer development.

CONCLUSION

Recent studies suggest that gut microbiota-derived metabolites have a role in CRC progression and causation and hence, could be implicated in CRC diagnosis, prognosis and therapy.

Alcohol intake in early adulthood and risk of colorectal cancer: three large prospective cohort studies of men and women in the United States

Heavy alcohol consumption in mid-adulthood is an established risk factor of colorectal cancer (CRC). Alcohol use in early adulthood is common, but its association with subsequent CRC risk remains largely unknown. We prospectively investigated the association of average alcohol intake in early adulthood (age 18-22) with CRC risk later in life among 191,543 participants of the Nurses' Health Study ([NHS], 1988-2014), NHSII (1989-2015) and Health Professionals Follow-Up Study (1988-2014). Cox proportional hazards models were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs), which were pooled using random effects models. We documented 2,624 CRC cases. High alcohol consumption in early adulthood (≥ 15 g/day) was associated with a higher CRC risk (multivariable HR 1.28, 95% CI 0.99-1.66, Ptrend = 0.02; Pheterogeneity = 0.44), after adjusting for potential confounding factors in early adulthood. Among never/light smokers in early adulthood, the risk associated with high alcohol consumption in early adulthood was elevated (HR 1.53, 95% CI 1.04-2.24), compared with those who had < 1 g/day of alcohol intake. The suggestive higher CRC risk associated with high alcohol consumption in early adulthood was similar in those who had < 15 g/day (HR 1.35, 95% CI 0.98-1.86) versus ≥ 15 g/day of midlife alcohol intake (HR 1.35, 95% CI 0.89-2.05), compared with nondrinkers in both life stages. The findings from these large prospective cohort studies suggest that higher alcohol intake in early adulthood may be associated with a higher risk of developing CRC later in life.

Alcohol consumption is associated with widespread changes in blood DNA methylation: Analysis of cross-sectional and longitudinal data

DNA methylation may be one of the mechanisms by which alcohol consumption is associated with the risk of disease. We conducted a large-scale, cross-sectional, genome-wide DNA methylation association study of alcohol consumption and a longitudinal analysis of repeated measurements taken several years apart. Using the Illumina HumanMethylation450 BeadChip, DNA methylation was measured in blood samples from 5606 Melbourne Collaborative Cohort Study (MCCS) participants. For 1088 of them, these measures were repeated using blood samples collected a median of 11 years later. Associations between alcohol intake and blood DNA methylation were assessed using linear mixed-effects regression models. Independent data from the London Life Sciences Prospective Population (LOLIPOP) (N = 4042) and Cooperative Health Research in the Augsburg Region (KORA) (N = 1662) cohorts were used to replicate associations discovered in the MCCS. Cross-sectional analyses identified 1414 CpGs associated with alcohol intake at P < 10-7 , 1243 of which had not been reported previously. Of these novel associations, 1078 were replicated (P < .05) using LOLIPOP and KORA data. Using the MCCS data, we also replicated 403 of 518 previously reported associations. Interaction analyses suggested that associations were stronger for women, non-smokers, and participants genetically predisposed to consume less alcohol. Of the 1414 CpGs, 530 were differentially methylated (P < .05) in former compared with current drinkers. Longitudinal associations between the change in alcohol intake and the change in methylation were observed for 513 of the 1414 cross-sectional associations. Our study indicates that alcohol intake is associated with widespread changes in DNA methylation across the genome. Longitudinal analyses showed that the methylation status of alcohol-associated CpGs may change with alcohol consumption changes in adulthood.

Western influenced lifestyle and Kv2.1 association as predicted biomarkers for Tunisian colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the third most diagnosed malignancy worldwide. The global burden is expected to increase along with ongoing westernized behaviors and lifestyle. The etiology of CRC remains elusive and most likely combines environmental and genetic factors. The Kv2.1 potassium channel encoded by KCNB1 plays a collection of roles in malignancy of cancer and may be a key factor of CRC susceptibility. Our study provides baseline association between Tunisian CRC and interactions between KCNB1 variants and lifestyle factors.

METHODS

A case-control study involving 300 CRC patients, and 300 controls was conducted Patients were carefully phenotyped and followed till the end of study. KCNB1 genotyping was confirmed by Sanger sequencing. Bivariate and multivariable logistic regression analyses were used to assess the clinical status, lifestyle and study polymorphisms association with CRC.

RESULTS

We noted significant gender association with CRC occurrence. Moreover, CRC risk increases with high meat and fat consumption, alcohol use and physical activity (PA). Carriage of rs1051296 A/G and both rs11468831 ins/del and del/del genotypes (p < 0.001) were significantly associated with CRC risk. Analysis according to gender reveals correlation of rs1051295 A/G, rs11468831 non ins/ins (p = 0.01) with CRC susceptibility regardless of patients' gender while rs3331 T/C (p = 0.012) was associated with females. Stratification study according to malignancy site; Rectal Cancer (RC) and Colon Cancer (CC), reveals increasing RC risk by gender and high meat and fat consumption, alcohol use and PA. However, additional association with high brine consumption was noted for CC. The rs1051295 A/G (p = 0.01) was associated with RC risk. Increased CC risk was associated with carriage of rs1051295 A/G, rs11168831 (del/del) and (ins/del) genotypes.

CONCLUSION

The risk of CRC increases with modifiable factors by Western influences on Tunisian lifestyle such as alcohol use, high fat consumption and possibly inadequate intake of vegetables. In addition, KCNB1 polymorphisms also markedly influence CRC susceptibility. Our study establishes key elements of a baseline characterization of clinical state, Western influenced lifestyle and KCNB1 variants associated with Tunisian CRC.

The relationship between colorectal cancer risk factors and LINE-1 DNA methylation in healthy colon tissue

Aim: LINE-1 DNA methylation is a modifiable epigenetic process linked to colorectal cancer (CRC). However, studies of methylation in the tissue of interest are limited. This research examines associations between CRC risk factors and LINE-1 DNA methylation in healthy colon tissue. Materials & methods: LINE-1 methylation was measured in colon tissue samples from 317 patients undergoing a screening colonoscopy. Associations were examined with established CRC risk factors including alcohol consumption, smoking, BMI, NSAIDs, physical activity and fruit and vegetable consumption. Results: All studied risk factors were not related to LINE-1 DNA methylation in this population. Conclusion: The observed results may reflect that the effect of this set of established risk factors is not mediated through LINE-1 DNA methylation in the healthy colon.

Global burden of colorectal cancer: emerging trends, risk factors and prevention strategies

Globally, colorectal cancer (CRC) is the third most commonly diagnosed malignancy and the second leading cause of cancer death. Arising through three major pathways, including adenoma-carcinoma sequence, serrated pathway and inflammatory pathway, CRC represents an aetiologically heterogeneous disease according to subtyping by tumour anatomical location or global molecular alterations. Genetic factors such as germline MLH1 and APC mutations have an aetiologic role, predisposing individuals to CRC. Yet, the majority of CRC is sporadic and largely attributable to the constellation of modifiable environmental risk factors characterizing westernization (for example, obesity, physical inactivity, poor diets, alcohol drinking and smoking). As such, the burden of CRC is shifting towards low-income and middle-income countries as they become westernized. Furthermore, the rising incidence of CRC at younger ages (before age 50 years) is an emerging trend. This Review provides a comprehensive summary of CRC epidemiology, with emphasis on modifiable lifestyle and nutritional factors, chemoprevention and screening. Overall, the optimal reduction of CRC incidence and mortality will require concerted efforts to reduce modifiable risk factors, to leverage chemoprevention research and to promote population-wide and targeted screening.

Contribution of Genetic Polymorphisms of Inflammation Response Genes on Sporadic Colorectal Cancer Predisposition Risk in Malaysian Patients - A Case Control Study

AIM: To investigate the frequencies and association of polymorphic genotypes of IL-8 -251 T>A, TNF-α -308 G>A, ICAM-1 K469E, ICAM-1 R241G, IL-6 -174 G>C, and PPAR-γ 34 C>G in modulating susceptibility risk in Malaysian colorectal cancer (CRC) patients. Methods: In this case-control study, peripheral blood samples of 560 study subjects (280 CRC patients and 280 controls) were collected, DNA extracted and genotyped using PCR-RFLP and Allele Specific PCR. The association between polymorphic genotype and CRC susceptibility risk was determined using Logistic Regression analysis deriving Odds ratio (OR) and 95% CI. Results: On comparing the frequencies of genotypes of all single nucleotide polymorphisms ( SNPs ) in patients and controls, the homozygous variant genotypes IL-8 -251 AA and TNF-α -308 AA and variant A alleles were significantly higher in CRC patients. Investigation on the association of the variant alleles and genotypes singly, with susceptibility risk showed the homozygous variant A alleles and genotypes IL-8 -251 AA and TNF-α -308 AA to be at higher risk for CRC predisposition. Analysis based on age, gender and smoking habits showed that the polymorphisms IL8 -251 T>A and TNF – α 308 G>A contribute to a significantly higher risk among male and female who are more than 50 years and for smokers in this population. Conclusion: We observed an association between variant allele and genotypes of IL-8-251 T>A and TNF-α-308 G>A polymorphisms and CRC susceptibility risk in Malaysian patients. These two SNPs in inflammatory response genes which undoubtedly contribute to individual risks to CRC susceptibility may be considered as potential genetic predisposition factors for CRC in Malaysian population.

[Epidemiological, nutritional and anatomopathological features of patients with colorectal cancer in the greater Casablanca region]

Introduction

le cancer colorectal constitue un problème majeur de santé publique. L’objectif de notre étude est d’analyser le profil épidémiologique, nutritionnel, clinique et anatomo-pathologique des cancers colorectaux recrutés au CHU de Casablanca.

Méthodes

notre étude cas-témoins a porté sur les patients pris en charge pour un cancer colorectal durant l’année 2015, comparés à des témoins non suivi pour un cancer.

Résultats

l’âge moyen des patients était de 56,65 ans avec un écart type de 14,64. Le type histologique le plus fréquent chez nos patients était représenté par l’adénocarcinome Lieberkühnien avec une proportion de 82 %. L’analyse de l’indice de masse corporelle a permis de retrouver une obésité chez 50% des patients contre 20% des témoins et un diabète chez 19% des patients versus 8% des témoins (p < 0,019). Par ailleurs, l’étude du régime alimentaire des patients comparé à celui des témoins semble montrer que la moyenne de la fréquence de consommation hebdomadaire de viandes rouges est plus élevée chez les patients que chez les témoins (4,24 vs 3,26; p = 0,009) et inversement pour la consommation du poisson (0,97 contre 1,76; p = 0,0001). En revanche, la moyenne de consommation des légumes et des fruits est plus faible chez les patients que chez les témoins (5,00 vs 9,50; p = 0,0001). Concernant les habitudes toxiques de nos patients, 32% des patients étaient fumeurs vs 13 % des témoins.

Conclusion

nos résultats montrent que la prise de conscience à propos du régime alimentaire et des changements dans nos habitudes de vie pourrait réduire l’incidence du cancer colorectal et par conséquent la mortalité et la morbidité.

Targeting DNA Hypomethylation in Malignancy by Epigenetic Therapies

DNA methylation is a chemically reversible epigenetic modification that regulates the chromatin structure and gene expression, and thereby takes part in various cellular processes like embryogenesis, genomic imprinting, X-chromosome inactivation, and genome stability. Alterations in the normal methylation levels of DNA may contribute to the development of pathological conditions like cancer. Even though both hypo- and hypermethylation-mediated abnormalities are prevalent in the cancer genome, the field of cancer epigenetics has been more focused on targeting hypermethylation. As a result, DNA hypomethylation-mediated abnormalities remained relatively less explored, and currently, there are no approved drugs that can be clinically used to target hypomethylation. Understanding the precise role of DNA hypomethylation is not only crucial from a mechanistic point of view but also for the development of pharmacological agents that can reverse the hypomethylated state of the DNA. This chapter focuses on the causes and impact of DNA hypomethylation in the development of cancer and describes the possible ways to pharmacologically target it, especially by using a naturally occurring physiologic agent S-adenosylmethionine (SAM).

Alcohol-Induced Epigenetic Changes in Cancer

Chronic, heavy alcohol consumption is associated with serious negative health effects, including the development of several cancer types. One of the pathways affected by alcohol toxicity is the one-carbon metabolism. The alcohol-induced impairment of this metabolic pathway results in epigenetic changes associated with cancer development. These epigenetic changes are induced by folate deficiency and by products of the ethanol metabolism. The changes induced by long-term heavy ethanol consumption result in elevations of homocysteine and S-adenosyl-homocysteine (SAH) and reductions in S-adenosylmethionine (SAM) and antioxidant glutathione (GSH) levels, leading to abnormal promoter gene hypermethylation, global hypomethylation, and metabolic insufficiency of antioxidant defense mechanisms. In addition, reactive oxygen species (ROS) generated during the ethanol metabolism induce alterations in DNA methylation patterns that play a critical role in cancer development. Specific epigenetic changes in esophageal, hepatic, and colorectal cancers have been detected in blood samples and proposed to be used clinically as epigenetic biomarkers for diagnosis and prognosis of these cancers. Also, genetic variants of genes involved in one-carbon metabolism and ethanol metabolism were found to modulate the relationship between alcohol-induced epigenetic changes and cancer risk. Furthermore, alcohol metabolism products have been associated with an increase in NADH levels, which lead to histone modifications and changes in gene expression that in turn influence cancer susceptibility. Chronic excessive use of alcohol also affects selected members of the family of microRNAs, and as miRNAs could act as epigenetic regulators, this may play an important role in carcinogenesis. In conclusion, targeting alcohol-induced epigenetic changes in several cancer types could make available clinical tools for the diagnosis, prognosis, and treatment of these cancers, with an important role in precision medicine.

The relationship between drinking alcohol and esophageal, gastric or colorectal cancer: A nationwide population-based cohort study of South Korea

BACKGROUND

Epidemiologic findings of low-volume alcohol consumption in relation to gastrointestinal cancers including gastric cancer are inconsistent.

METHODS

The association between alcohol intake and esophageal, gastric and colorectal cancer risk was examined in a population-based prospective cohort of 23,323,730 adults in Korea who had undergone a biennial evaluation provided by the National Health Insurance Corporation between the years 2009 and 2012. After median 5.4 years of follow-up, 9,171 esophageal, 135,382 gastric and 154,970 colorectal cancer cases were identified. Cox regression models were used to estimate hazard ratios (HR) and corresponding 95% confidence intervals (95% CI).

RESULTS

Light drinking as well as moderate to heavy alcohol consumption significantly increased the risks of the three gastrointestinal cancers (HR 1.51; 95% CI, 1.43-1.60; HR 1.08; 95% CI, 1.06-1.09; HR 1.12; 95% CI, 1.11-1.14) compared with non-drinkers after adjusting for age, sex, smoking, exercise, income, body mass index, and diabetes. The synergistically increased cancer risk between excessive amount of alcohol consumption and currently smoking or underweight individuals was observed only in the esophageal cancers.

CONCLUSIONS

Light drinking including even one alcoholic drink a day is associated with increased risks of esophageal, gastric and colorectal cancer.

Nature, Nurture, and Cancer Risks: Genetic and Nutritional Contributions to Cancer

It is speculated that genetic variants are associated with differential responses to nutrients (known as gene-diet interactions) and that these variations may be linked to different cancer risks. In this review, we critically evaluate the evidence across 314 meta-analyses of observational studies and randomized controlled trials of dietary risk factors and the five most common cancers (breast, lung, prostate, colorectal, and stomach). We also critically evaluate the evidence across 13 meta-analyses of observational studies of gene-diet interactions for the same cancers. Convincing evidence for association was found only for the intake of alcohol and whole grains in relation to colorectal cancer risk. Three nutrient associations had highly suggestive evidence and another 15 associations had suggestive evidence. Among the examined gene-diet interactions, only one had moderately strong evidence.

Molecular Basis of Alcohol-Related Gastric and Colon Cancer

Many meta-analysis, large cohort studies, and experimental studies suggest that chronic alcohol consumption increases the risk of gastric and colon cancer. Ethanol is metabolized by alcohol dehydrogenases (ADH), catalase or cytochrome P450 2E1 (CYP2E1) to acetaldehyde, which is then further oxidized to acetate by aldehyde dehydrogenase (ALDH). Acetaldehyde has been classified by the International Agency for Research on Cancer (IARC) as a Group 1 carcinogen to humans. The acetaldehyde level in the stomach and colon is locally influenced by gastric colonization by Helicobacter pylori or colonic microbes, as well as polymorphisms in the genes encoding tissue alcohol metabolizing enzymes, especially ALDH2. Alcohol stimulates the uptake of carcinogens and their metabolism and also changes the composition of enteric microbes in a way to enhance the aldehyde level. Alcohol also undergoes chemical coupling to membrane phospholipids and disrupts organization of tight junctions, leading to nuclear translocation of β-catenin and ZONAB, which may contributes to regulation of genes involved in proliferation, invasion and metastasis. Alcohol also generates reactive oxygen species (ROS) by suppressing the expression of antioxidant and cytoprotective enzymes and inducing expression of CYP2E1 which contribute to the metabolic activation of chemical carcinogens. Besides exerting genotoxic effects by directly damaging DNA, ROS can activates signaling molecules involved in inflammation, metastasis and angiogenesis. In addition, alcohol consumption induces folate deficiency, which may result in aberrant DNA methylation profiles, thereby influencing cancer-related gene expression.

Alcohol consumption, genetic variants in the alcohol- and folate metabolic pathways and colorectal cancer risk: the JPHC Study

The association between alcohol intake and colorectal cancer (CRC) may vary secondary to single nucleotide polymorphisms (SNPs) in two pathways related to alcohol intake. 375 cases of CRC were identified among 38 373 Japan Public Health Center-based prospective Study (JPHC Study) participants who had returned a baseline questionnaire, reported no diagnosis of any cancer and provided blood samples. For each case, two controls were selected on matching variables. Logistic regression models were used to determine matched Odds Ratios (OR) and 95% Confidence Intervals (CI) for the association between alcohol consumption, genetic polymorphisms of enzymes in the alcohol- and folate metabolic pathways (e.g. methylenetetrahydrofolate reductase (MTHFR) rs1801133) and CRC risk. Compared to never/occasional alcohol intake, moderate to heavy alcohol intake was associated with CRC (OR = 2.12, 95% CI, 1.34–3.36). When compared to the CC genotype, the MTHFR rs1801133 CT/TT genotype was inversely associated with CRC (OR = 0.72, 95% CI, 0.54–0.97). Never/occasional consumers of alcohol with the MTHFR rs1801133 CT/TT genotype were also at a reduced risk of CRC compared to never/occasional drinkers with the CC genotype (OR = 0.68, 95% CI, 0.47–0.98) (P for interaction = 0.27). The results indicate that the folate pathway is likely to be involved in alcohol-related CRC development.

Effects of the lifestyle habits in breast cancer transcriptional regulation

Through research carried out in the last 25 years about the breast cancer etiology, it has been possible to estimate that less than 10 % of patients who are diagnosed with the condition are carriers of some germline or somatic mutation. The clinical reports of breast cancer patients with healthy twins and the development of disease in women without high penetrance mutations detected, warn the participation more factors in the transformation process. The high incidence of mammary adenocarcinoma in the modern woman and the urgent need for new methods of prevention and early detection have demanded more information about the role that environment and lifestyle have on the transformation of mammary gland epithelial cells. Obesity, alcoholism and smoking are factors that have shown a close correlation with the risk of developing breast cancer. And although these conditions affect different cell regulation levels, the study of its effects in the mechanisms of transcriptional and epigenetic regulation is considered critical for a better understanding of the loss of identity of epithelial cells during carcinogenesis of this tissue. The main objective of this review was to establish the importance of changes occurring to transcriptional level in the mammary gland as a consequence of acute or chronic exposure to harmful products such as obesity-causing foods, ethanol and cigarette smoke components. At analyze the main studies related to topic, it has concluded that the understanding of effects caused by the lifestyle factors in performance of the transcriptional mechanisms that determine gene expression of the mammary gland epithelial cells, may help explain the development of this disease in women without genetic propensity and different phenotypic manifestations of this cancer type.

Intake of vitamins A, C, and E and folate and the risk of ovarian cancer in a pooled analysis of 10 cohort studies

PURPOSE

Vitamins A, C, and E and folate have anticarcinogenic properties and thus might protect against cancer. Few known modifiable risk factors for ovarian cancer exist. We examined the associations between dietary and total (food and supplemental) vitamin intake and the risk of invasive epithelial ovarian cancer.

METHODS

The primary data from 10 prospective cohort studies in North America and Europe were analyzed. Vitamin intakes were estimated from validated food frequency questionnaires in each study. Study-specific relative risks (RRs) were estimated using the Cox proportional hazards model and then combined using a random-effects model.

RESULTS

Among 501,857 women, 1,973 cases of ovarian cancer occurred over a median follow-up period of 7-16 years across studies. Dietary and total intakes of each vitamin were not significantly associated with ovarian cancer risk. The pooled multivariate RRs [95% confidence intervals (CIs)] for incremental increases in total intake of each vitamin were 1.02 (0.97-1.07) for vitamin A (increment: 1,300 mcg/day), 1.01 (0.99-1.04) for vitamin C (400 mg/day), 1.02 (0.97-1.06) for vitamin E (130 mg/day), and 1.01 (0.96-1.07) for folate (250 mcg/day). Multivitamin use (vs. nonuse) was not associated with ovarian cancer risk (pooled multivariate RR = 1.00, 95% CI 0.89-1.12). Associations did not vary substantially by study, or by subgroups of the population. Greater vitamin intakes were associated with modestly higher risks of endometrioid tumors (n = 156 cases), but not with other histological types.

CONCLUSION

These results suggest that consumption of vitamins A, C, and E and folate during adulthood does not play a major role in ovarian cancer risk.

Moderate Alcohol Consumption and Colorectal Cancer Risk

BACKGROUND

Heavy alcohol drinking is a risk factor for colorectal cancer (CRC); previous studies have shown a linear dose-dependent association between alcohol intake and CRC. However, some studies suggest that moderate alcohol consumption may have a protective effect, similar to that seen in cardiovascular disease. Other factors may interact with alcohol and contribute additional risk for CRC. We aimed to determine the association between moderate alcohol consumption, limited to 30 g of alcohol per day, by beverage type on CRC risk and to assess the effects of other factors that interact with alcohol to influence CRC risk.

METHODS

The PubMed database was used to find articles published between 2008 and 2014 related to alcohol and CRC. Twenty-one relevant articles were evaluated and summarized, including 11 articles reporting on CRC risk associated with moderate intake and 10 articles focusing on genetic interactions associated with alcohol and CRC risk.

RESULTS

The association between alcohol and increased risk for CRC was found when intakes exceeded 30 g/d alcohol. Nonsignificant results were consistently reported for intakes <30 g/d. Additional risks for CRC were found to be related to obesity and folate status for regular alcohol consumers. Some significant results suggest that the development of CRC is dependent on the interaction of gene and environment.

CONCLUSIONS

The association between the amount of alcohol consumed and the incidence of CRC was not significant at moderate intake levels. Moderate alcohol consumption was associated with a reduced CRC risk in study populations with greater adherence to a Mediterranean diet, where wine contributed substantially to the alcoholic beverage consumed. Other factors such as obesity, folate deficiency, and genetic susceptibility may contribute additional CRC risk for those consuming alcohol. To minimize CRC risk, appropriate recommendations should encourage intakes below 30 g of alcohol each day.

Alcohol intake, smoking, and colorectal adenoma

Background:

Colorectal cancer is the third most common cancer in Korea. Because colorectal adenoma is a precursor lesion of colorectal cancer, primary prevention of colorectal adenomas may be important for reducing morbidity and mortality from the disease. The aim of this study is to examine the association of alcohol consumption and cigarette smoking in relation with colorectal adenoma in a cross-sectional study of Korean adults.

Methods:

A total of 366 participants who underwent colonoscopy were included (113 cases and 255 controls) in this study. Information on alcohol intake and cigarette smoking was collected from structured questionnaires. The odds ratio (ORs) and 95% confidence intervals (CIs) were calculated using the multivariate logistic regression models.

Results:

Alcohol intake was associated with a higher prevalence of colorectal adenoma in men; compared to non-drinkers, ORs (95% CIs) were 11.49 (2.55–51.89) for 10–20 g/day of alcohol intake and 14.15 (3.31–60.59) for â 20 g/day of alcohol intake (P for trend = 0.003). There was a weaker association of alcohol intake for women than men; however, there was a suggestive increase in the prevalence of colorectal cancer in women. Cigarette smoking was not associated with colorectal adenoma, but we cannot rule out the possibility that this was due to low statistical power.

Conclusion:

Our study provides evidence to suggest that alcohol intake may contribute to colorectal adenoma in the Korean population. Our study results demonstrate that a larger epidemiologic study is needed.

Systematic review with meta-analysis: alcohol consumption and the risk of colorectal adenoma

BACKGROUND

Studies on the relation between alcohol consumption and risk of colorectal adenoma (CRA), a precursor of colorectal cancer, have been inconsistent.

AIM

A systematic review with meta-analysis was conducted to investigate the association and the dose-response of alcohol with CRA.

METHODS

A literature search was performed on PubMed to identify relevant studies published up to January 2014. A fixed or random effects model was used to estimate summarised relative risks (RRs) and 95% confidence intervals (CIs) for the association between alcohol intake and CRA risk. Statistical heterogeneity between studies was assessed with the χ(2) statistic and quantified by I².

RESULTS

Twenty-three case-control studies and two cohort studies were included in the meta-analysis. All drinkers were associated with 17% increased risk for CRA, compared with nondrinkers or occasional alcohol drinkers. The dose-response analysis demonstrated that for drinkers of 10, 25, 50 and 100 g/day alcohol consumption, the estimated RRs of CRA were 1.02 (95% CI 0.89-1.16), 1.06 (95% CI 0.92-1.20), 1.16 (95% CI 1.02-1.33) and 1.61 (95% CI 1.42-1.84) respectively, in comparison with non-/occasional drinkers. The risks were consistent in the subgroup analyses of gender and site of adenoma, while it was stronger in European studies than the studies in the US and Asia.

CONCLUSIONS

This study suggests that alcohol intake is related to a significant increase of risk for colrectal adenoma.

Dietary one-carbon nutrient intake and risk of lymphoid and myeloid neoplasms: results of the Netherlands cohort study

BACKGROUND

Previous epidemiologic research suggests a protective role of one-carbon nutrients in carcinogenesis. Folate, however, may play a dual role in neoplasms development: protect early in carcinogenesis and promote carcinogenesis at a later stage. We prospectively examined associations between intake of total folate, methionine, riboflavin, vitamin B6, and risk of lymphoid and myeloid neoplasms (including subtypes) and investigated whether alcohol modified the effects of folate.

METHODS

The Netherlands Cohort Study consists of 120,852 individuals who completed a baseline questionnaire in 1986, including a 150-item food-frequency questionnaire. After 17.3 years of follow-up, 1,280 cases of lymphoid and 222 cases of myeloid neoplasms were available for analysis.

RESULTS

Intakes of folate, methionine, and riboflavin were not associated with lymphoid or myeloid neoplasms. For vitamin B6, a statistically significantly increased myeloid neoplasms risk was observed (highest vs. lowest quintile: HR = 1.87; 95% confidence intervals, 1.08-3.25). When analyzing by lymphoid and myeloid neoplasms subtypes, no clear associations were observed for most subtypes, with just a few increased risks for some subtypes and nutrients. Some risks became nonsignificant after excluding early cases. No interaction between alcohol and folate was observed.

CONCLUSIONS

We observed a few significant positive associations; however, some of these would be expected to arise due to chance alone. Furthermore, some risks became nonsignificant after excluding early cases. Therefore, we conclude that there is no association between one-carbon nutrient intake and risk of lymphoid and myeloid neoplasms.

IMPACT

This study contributes substantially to the limited and inconclusive evidence on the association with one-carbon nutrients.

Genetic polymorphisms in the microRNA binding-sites of the thymidylate synthase gene predict risk and survival in gastric cancer

Thymidylate synthase (TYMS) plays a crucial role in folate metabolism as well as DNA synthesis and repair. We hypothesized that functional polymorphisms in the 3' UTR of TYMS are associated with gastric cancer risk and survival. In the present study, we tested our hypothesis by genotyping three potentially functional (at miRNA binding sites) TYMS SNPs (rs16430 6bp del/ins, rs2790 A>G and rs1059394 C>T) in 379 gastric cancer patients and 431 cancer-free controls. Compared with the rs16430 6bp/6bp + 6bp/0bp genotypes, the 0bp/0bp genotype was associated with significantly increased gastric cancer risk (adjusted OR = 1.72, 95% CI = 1.15-2.58). Similarly, rs2790 GG and rs1059394 TT genotypes were also associated with significantly increased risk (adjusted OR = 2.52, 95% CI = 1.25-5.10 and adjusted OR = 1.57, 95% CI = 1.04-2.35, respectively), compared with AA + AG and CC + CT genotypes, respectively. In the haplotype analysis, the T-G-0bp haplotype was associated with significantly increased gastric cancer risk, compared with the C-A-6bp haplotype (adjusted OR = 1.34, 95% CI = 1.05-1.72). Survival analysis revealed that rs16430 0bp/0bp and rs1059394 TT genotypes were also associated with poor survival in gastric cancer patients who received chemotherapy treatment (adjusted HR = 1.61, 95% CI = 1.05-2.48 and adjusted HR = 1.59, 95% CI = 1.02-2.48, respectively). These results suggest that these three variants in the miRNA binding sites of TYMS may be associated with cancer risk and survival of gastric cancer patients. Larger population studies are warranted to verify these findings.

Impaired one carbon metabolism and DNA methylation in alcohol toxicity

Excessive alcohol consumption is a prominent problem and one of the major causes of mortality and morbidity around the world. Long-term, heavy alcohol consumption is associated with a number of deleterious health consequences, such as cancer, heart and liver disease, a variety of neurological, cognitive, and behavioral deficits. Alcohol consumption is also associated with developmental defects. The causes of alcohol-induced toxicity are presently unclear. One of the mechanisms underlying alcohol toxicity has to do with its interaction with folic acid/homocysteine or one-carbon metabolism (OCM). OCM is a major donor of methyl groups for methylation, particularly DNA methylation critical for epigenetic regulation of gene expression, and its disturbance may compromise DNA methylation, thereby affecting gene expression. OCM disturbance mediated by nutrient deficits is a well-known risk factor for various disorders and developmental defects (e.g., neural tube defects). In this review, we summarize the role of OCM disturbance and associated epigenetic aberrations in chronic alcohol-induced toxicity. In this review, we summarize the role of one-carbon metabolism (OCM) aberrations in chronic alcohol-induced toxicity. OCM is a major donor of methyl groups for methylation reactions, particularly DNA methylation critical for epigenetic regulation of gene expression. Alcohol interference with OCM and consequent reduced availability of methyl groups, improper DNA methylation, and aberrant gene expression can play a causative role in alcohol toxicity.

Integrating early life experience, gene expression, brain development, and emergent phenotypes: unraveling the thread of nature via nurture

Adaptation to environmental changes is based on the perpetual generation of new phenotypes. Modern biology has focused on the role of epigenetic mechanisms in facilitating the adaptation of organisms to changing environments through alterations in gene expression. Inherited and/or acquired epigenetic factors are relatively stable and have regulatory roles in numerous genomic activities that translate into phenotypic outcomes. Evidence that dietary and pharmacological interventions have the potential to reverse environment-induced modification of epigenetic states (e.g., early life experience, nutrition, medication, infection) has provided an additional stimulus for understanding the biological basis of individual differences in cognitive abilities and disorders of the brain. It has been suggested that accurate quantification of the relative contribution of heritable genetic and epigenetic variation is essential for understanding phenotypic divergence and adaptation in changing environments, a process requiring stable modulation of gene expression. The main challenge for epigenetics in psychology and psychiatry is to determine how experiences and environmental cues, including the nature of our nurture, influence the expression of neuronal genes to produce long-term individual differences in behavior, cognition, personality, and mental health. To this end, focusing on DNA and histone modifications and their initiators, mediators and readers may provide new inroads for understanding the molecular basis of phenotypic plasticity and disorders of the brain. In this chapter, we review recent discoveries highlighting epigenetic aspects of normal brain development and mental illness, as well as discuss some future directions in the field of behavioral epigenetics.

Socio-economic differences in food group and nutrient intakes among young women in Ireland

The present study aimed to investigate socio-economic disparities in food and nutrient intakes among young Irish women. A total of 221 disadvantaged and seventy-four non-disadvantaged women aged 18-35 years were recruited. Diet was assessed using a diet history protocol. Of the total population, 153 disadvantaged and sixty-three non-disadvantaged women were classified as plausible dietary reporters. Food group intakes, nutrient intakes and dietary vitamin and mineral concentrations per MJ of energy consumed were compared between the disadvantaged and non-disadvantaged populations, as was compliance with dietary fibre, macronutrient and micronutrient intake guidelines. The disadvantaged women had lower intakes than the non-disadvantaged women of fruit, vegetables, fish, breakfast cereals, low-fat milk and wholemeal bread (all P< 0·001), yogurt (P= 0·001), low-fat spread (P= 0·002) and fresh meat (P= 0·003). They also had higher intakes of butter, processed red meats, white bread, sugar-sweetened beverages, fried potatoes and potato-based snacks (all P< 0·001) and full-fat milk (P= 0·014). Nutritionally, the disadvantaged women had higher fat, saturated fat and refined sugar intakes; lower dietary fibre, vitamin and mineral intakes; and lower dietary vitamin and mineral densities per MJ than their more advantaged peers. Non-achievement of carbohydrate (P= 0·017), fat (P< 0·001), saturated fat (P< 0·001), refined sugar (P< 0·001), folate (P= 0·050), vitamin C (P< 0·001), vitamin D (P= 0·047) and Ca (P= 0·019) recommendations was more prevalent among the disadvantaged women. Both groups showed poor compliance with Fe and Na guidelines. We conclude that the nutritional deficits present among these socially disadvantaged women are significant, but may be potentially ameliorated by targeted food-based interventions.

Prospective study of alcohol consumption and the risk of colorectal cancer before and after folic acid fortification in the United States

PURPOSE

To evaluate the influence of alcohol consumption on the risk of colorectal cancer according to folic acid fortification period in the United States.

METHODS

We evaluated the association between alcohol consumption and colorectal cancer by fortification period (before 1998 vs. after 1998) in 2 prospective cohort studies, the Nurses' Health Study (NHS) of women and the Health Professionals Follow-up Study (HPFS) of men, in which 2793 cases of invasive colorectal cancer were documented.

RESULTS

Alcohol consumption was associated with an increased risk of colorectal cancer. Among nonusers of multivitamins and/or folic acid supplements, the pooled multivariate relative risk for ≥30 g/d drinkers versus nondrinkers was 1.36 (95% confidence interval [95% CI], 1.09-1.70; P for trend, 0.02). The effect of alcohol consumption was slightly stronger in the prefolic acid fortification period (1980 NHS/1986 HPFS-1998) than in the postfortification period (1998-2008); the pooled multivariate relative risks for ≥30 g/d drinkers versus nondrinkers were 1.31 (95% CI, 1.00-1.71; P for trend, 0.10) in the prefortification period and 1.07 (95% CI, 0.69-1.65; P for trend, 0.67) in the postfortification period.

CONCLUSIONS

Folic acid fortification may attenuate the adverse effect of high alcohol consumption on the risk of colorectal cancer.

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.

Pre-diagnostic leukocyte genomic DNA methylation and the risk of colorectal cancer in women

BACKGROUND

Abnormal one-carbon metabolism may lead to general genomic (global) hypomethylation, which may predispose an individual to the development of colorectal neoplasia.

METHODS

We evaluated the association between pre-diagnostic leukocyte genomic DNA methylation level and the risk of colorectal cancer in a nested case-control study of 358 colorectal cancer cases and 661 matched controls within the all-female cohort of the Nurses' Health Study (NHS). Among control subjects, we further examined major plasma components in the one-carbon metabolism pathway in relation to genomic DNA methylation level. Liquid chromatography/tandem mass spectrometry was used to examine leukocyte genomic DNA methylation level. We calculated odds ratios (ORs) and 95% confidence intervals (95% CIs) using logistic regression.

RESULTS

Overall genomic DNA methylation level was not associated with the risk of colorectal cancer (p for trend, 0.45). Compared with women in the lowest quintile of methylation, the multivariate OR of colorectal cancer risk was 1.32 (95% CI, 0.82-2.13) for those in the highest quintile. We did not find significant associations between major plasma components of one-carbon metabolism or risk factors for colorectal cancer and genomic DNA methylation level (all p for trend >0.05). Also, neither one-carbon metabolism-related plasma components nor well-known risk factors for colorectal cancer modified the association between genomic DNA methylation level and the risk of colorectal cancer (all p for interaction >0.05).

CONCLUSIONS

We found no evidence that hypomethylation of leukocyte genomic DNA increases risk of colorectal cancer among women. Additional studies are needed to investigate the association between pre-diagnostic genomic DNA methylation level and colorectal cancer risk among diverse populations.

Light alcohol drinking and cancer: a meta-analysis

BACKGROUND

There is convincing evidence that alcohol consumption increases the risk of cancer of the colorectum, breast, larynx, liver, esophagus, oral cavity and pharynx. Most of the data derive from studies that focused on the effect of moderate/high alcohol intakes, while little is known about light alcohol drinking (up to 1 drink/day).

PATIENTS AND METHODS

We evaluated the association between light drinking and cancer of the colorectum, breast, larynx, liver, esophagus, oral cavity and pharynx, through a meta-analytic approach. We searched epidemiological studies using PubMed, ISI Web of Science and EMBASE, published before December 2010.

RESULTS

We included 222 articles comprising ∼92 000 light drinkers and 60 000 non-drinkers with cancer. Light drinking was associated with the risk of oropharyngeal cancer [relative risk, RR = 1.17; 95% confidence interval (CI) 1.06-1.29], esophageal squamous cell carcinoma (SCC) (RR = 1.30; 95% CI 1.09-1.56) and female breast cancer (RR = 1.05; 95% CI 1.02-1.08). We estimated that ∼5000 deaths from oropharyngeal cancer, 24 000 from esophageal SCC and 5000 from breast cancer were attributable to light drinking in 2004 worldwide. No association was found for colorectum, liver and larynx tumors.

CONCLUSIONS

Light drinking increases the risk of cancer of oral cavity and pharynx, esophagus and female breast.

Systemic folate status, rectal mucosal folate concentration and dietary intake in patients at differential risk of bowel cancer (The FAB2 Study)

BACKGROUND/OBJECTIVES

Folate has been strongly implicated in the aetiology of colorectal cancer. However, the relationship between dietary folate intake, rectal mucosal folate status and colorectal cancer risk is uncertain. The study aimed to estimate nutrient intakes and measure systemic folate status and rectal mucosal folate concentration in people at differential risk of developing colorectal cancer.

METHODS

Two hundred and twenty-eight individuals were recruited from gastroenterology clinics and subdivided into three patient groups: untreated colorectal cancer (n = 43), adenomatous polyps (n = 90) or normal bowel (n = 95). Biopsies from macroscopically normal rectal mucosa and blood were collected and used for the measurement of rectal mucosal 5-methyltetrahydrofolate (5-MeTHF) and systemic markers of folate status, respectively. Nutrient intake was estimated using a validated food frequency questionnaire.

RESULTS

Dietary intake variables, plasma 5-MeTHF and red cell folate and plasma homocysteine concentrations were similar in all three subject groups and 95% CI fell within normal range for each variable. Rectal mucosal 5-MeTHF concentration was higher in the normal mucosa of adenomatous polyp patients than in normal subjects (P = 0.055). Rectal mucosal 5-MeTHF was associated significantly with plasma folate (P < 0.001, r = 0.294), red cell folate (P = 0.014, r = 0.305), plasma homocysteine (P = 0.017, r = -0.163) and dietary folate intake (P = 0.036, r = 0.152).

CONCLUSIONS

This study demonstrates adequate folate status of patients attending gastroenterology clinics for the investigation of bowel symptoms, with no significant difference in dietary intakes or systemic folate status indices according to diagnosis. Rectal mucosal 5-MeTHF concentrations were elevated in adenomatous polyp patients, but failed to reach significance. Further studies are required to determine the biological significance of this observation.

North–south gradients in plasma concentrations of B-vitamins and other components of one-carbon metabolism in Western Europe: results from the European Prospective Investigation into Cancer and Nutrition (EPIC) Study

Different lifestyle patterns across Europe may influence plasma concentrations of B-vitamins and one-carbon metabolites and their relation to chronic disease. Comparison of published data on one-carbon metabolites in Western European regions is difficult due to differences in sampling procedures and analytical methods between studies. The present study aimed, to compare plasma concentrations of one-carbon metabolites in Western European regions with one laboratory performing all biochemical analyses. We performed the present study in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort among 5446 presumptively healthy individuals. Quantile regression was used to compare sex-specific median concentrations between Northern (Denmark and Sweden), Central (France, Germany, The Netherlands and United Kingdom) and Southern (Greece, Spain and Italy) European regions. The lowest folate concentrations were observed in Northern Europe (men, 10·4 nmol/l; women, 10·7 nmol/l) and highest concentrations in Central Europe. Cobalamin concentrations were slightly higher in Northern Europe (men, 330 pmol/l; women, 352 pmol/l) compared with Central and Southern Europe, but did not show a clear north–south gradient. Vitamin B2 concentrations were highest in Northern Europe (men, 22·2 nmol/l; women, 26·0 nmol/l) and decreased towards Southern Europe (Ptrend< 0·001). Vitamin B6 concentrations were highest in Central Europe in men (77·3 nmol/l) and highest in the North among women (70·4 nmol/l), with decreasing concentrations towards Southern Europe in women (Ptrend< 0·001). In men, concentrations of serine, glycine and sarcosine increased from the north to south. In women, sarcosine increased from Northern to Southern Europe. These findings may provide relevant information for the study of regional differences of chronic disease incidence in association with lifestyle.

Alcohol dehydrogenase and aldehyde dehydrogenase gene polymorphisms, alcohol intake and the risk of colorectal cancer in the European Prospective Investigation into Cancer and Nutrition study

BACKGROUND/OBJECTIVES

Heavy alcohol drinking is a risk factor of colorectal cancer (CRC), but little is known on the effect of polymorphisms in the alcohol-metabolizing enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) on the alcohol-related risk of CRC in Caucasian populations.

SUBJECTS/METHODS

A nested case-control study (1269 cases matched to 2107 controls by sex, age, study centre and date of blood collection) was conducted within the European Prospective Investigation into Cancer and Nutrition (EPIC) to evaluate the impact of rs1229984 (ADH1B), rs1573496 (ADH7) and rs441 (ALDH2) polymorphisms on CRC risk. Using the wild-type variant of each polymorphism as reference category, CRC risk estimates were calculated using conditional logistic regression, with adjustment for matching factors.

RESULTS

Individuals carrying one copy of the rs1229984(A) (ADH1B) allele (fast metabolizers) showed an average daily alcohol intake of 4.3 g per day lower than subjects with two copies of the rs1229984(G) allele (slow metabolizers) (P(diff)<0.01). None of the polymorphisms was associated with risk of CRC or cancers of the colon or rectum. Heavy alcohol intake was more strongly associated with CRC risk among carriers of the rs1573496(C) allele, with odds ratio equal to 2.13 (95% confidence interval: 1.26-3.59) compared with wild-type subjects with low alcohol consumption (P(interaction)=0.07).

CONCLUSIONS

The rs1229984(A) (ADH1B) allele was associated with a reduction in alcohol consumption. The rs1229984 (ADH1B), rs1573496 (ADH7) and rs441 (ALDH2) polymorphisms were not associated with CRC risk overall in Western-European populations. However, the relationship between alcohol and CRC risk might be modulated by the rs1573496 (ADH7) polymorphism.

DNA damage and neurotoxicity of chronic alcohol abuse

Chronic alcohol abuse results in a variety of pathological effects including damage to the brain. The causes of alcohol-induced brain pathology are presently unclear. Several mechanisms of pathogenicity of chronic alcoholism have been proposed, including accumulation of DNA damage in the absence of repair, resulting in genomic instability and death of neurons. Genomic instability is a unified genetic mechanism leading to a variety of neurodegenerative disorders. Ethanol also likely interacts with various metabolic pathways, including one-carbon metabolism (OCM). OCM is critical for the synthesis of DNA precursors, essential for DNA repair, and as a methyl donor for various methylation events, including DNA methylation. Both DNA repair and DNA methylation are critical for maintaining genomic stability. In this review, we outline the role of DNA damage and DNA repair dysfunction in chronic alcohol-induced neurodegeneration.

Epigenetic changes in response to tai chi practice: a pilot investigation of DNA methylation marks

Tai chi exercise has been shown to improve physiological and psychosocial functions, well-being, quality of life, and disease conditions. The biological mechanisms by which tai chi exerts its holistic effects remain unknown. We investigated whether tai chi practice results in positive epigenetic changes at the molecular level. Design. The DNA methylation profiles of sixty CpG-dinucleotide marks in female tai chi practitioners (N = 237; 45–88 years old) who have been practising tai chi for three or more years were compared with those of age-matched control females (N = 263) who have never practised tai chi. Results. Six CpG marks originating from three different chromosomes reveal a significant difference (P < 0.05) between the two cohorts. Four marks show losses while two marks show gains in DNA methylation with age in the controls. In the tai chi cohort all six marks demonstrate significant slowing (by 5–70%) of the age-related methylation losses or gains observed in the controls, suggesting that tai chi practice may be associated with measurable beneficial epigenetic changes. Conclusions. The results implicate the potential use of DNA methylation as an epigenetic biomarker to better understand the biological mechanisms and the health and therapeutic efficacies of tai chi.

Hypomethylation of repeated DNA sequences in cancer

An important feature of cancer development and progression is the change in DNA methylation patterns, characterized by the hypermethylation of specific genes concurrently with an overall decrease in the level of 5-methylcytosine. Hypomethylation of the genome can affect both single-copy genes, repeat DNA sequences and transposable elements, and is highly variable among and within cancer types. Here, we review our current understanding of genome hypomethylation in cancer, with a particular focus on hypomethylation of the different classes and families of repeat sequences. The emerging data provide insights into the importance of methylation of different repeat families in the maintenance of chromosome structural integrity and the fidelity of normal transcriptional regulation. We also consider the events underlying cancer-associated hypomethylation and the potential for the clinical use of characteristic DNA methylation changes in diagnosis, prognosis or classification of tumors.

Dietary intake of folate and alcohol, MTHFR C677T polymorphism, and colorectal cancer risk in Korea

BACKGROUND

The incidence of colorectal cancer (CRC) is increasing sharply in Korea, and evidence has suggested the role of dietary methyl supply and related polymorphisms on colorectal carcinogenesis.

OBJECTIVE

We investigated the association between folate and alcohol intake, methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism, and CRC risk in Koreans.

DESIGN

A total of 787 cases and 656 controls were recruited from 2 university hospitals. Multiple logistic regression models were used to estimate ORs and corresponding 95% CIs.

RESULTS

MTHFR 677T homozygotes were at a lower risk of CRC (OR: 0.60; 95% CI: 0.46, 0.78 for TT compared with CC/CT). High folate intake was associated with reduced CRC risk (OR: 0.64; 95% CI: 0.49, 0.84 for high compared with low intake), and high alcohol consumption was associated with increased risk of CRC (OR: 1.76; 95% CI: 1.26, 2.46 for high compared with low intake). When data were stratified by the amount of dietary methyl (combined intake of folate and alcohol), those with low-methyl diets had higher risk of CRC (OR: 2.32; 95% CI: 1.18, 4.56) than did those with high-methyl diets among CC/CT carriers, whereas the amount of dietary methyl did not affect the CRC risk among carriers with the TT homozygous variant. This association was stronger in patients with colon cancer than in patients with rectal cancer.

CONCLUSION

We found that the effect of dietary methyl supply on colorectal carcinogenesis may differ according to MTHFR C677T genotype and the subsite of origin in a Korean population.

Alcohol intake and colorectal cancer risk by molecularly defined subtypes in a prospective study of older women

Increased alcohol consumption is a putative colorectal cancer (CRC) risk factor. However, existing data are less conclusive for women than men. Also, to date, relatively few studies have reported alcohol-related CRC risks based on molecularly defined tumor subtypes. We evaluated associations between alcohol intake and incident CRC, overall and by microsatellite instability [MSI high (MSI-H) or MSI low/microsatellite stable (MSI-L/MSS)], CpG island methylator phenotype (CIMP positive or CIMP negative), and BRAF mutation (mutated or wild-type) status in the prospective, population-based Iowa Women's Health Study (IWHS; n = 41,836). Subjects were 55 to 69 years at baseline (1986), and exposure data were obtained by self-report. Incident CRCs were prospectively identified and archived, paraffin-embedded tissue specimens were collected from 732 representative cases, diagnosed through December 31, 2002. Multivariate Cox regression models were fit to estimate relative risks (RR) and 95% confidence intervals (CI). Among alcohol consumers, the median intake (range) was 3.4 (0.9-292.8) g/d. Compared with nonconsumers, alcohol intake levels of 3.4 g/d or less (RR = 1.00; 95% CI, 0.86-1.15) and more than 3.4 g/d (RR = 1.06; 95% CI, 0.91-1.24) were not significantly associated with overall CRC risk. Analyses based on alcohol intake levels of 30 g/d or less and more than 30 g/d or quartile distributions yielded similar risk estimates. Null associations were also observed between each alcohol intake level and the MSI-, CIMP- or, BRAF-defined CRC subtypes (P > 0.05 for each comparison). These data do not support an adverse effect from alcohol intake on CRC risk, overall or by specific molecularly defined subtypes, among older women.

Colorectal cancer screening and prevention in women

Colorectal cancer (CRC) is the third most common cause of cancer in women. Screening for CRC increases early detection of cancer and premalignant polyps and decreases morbidity from this disease. However, adherence to the screening guidelines continues to remain inadequate both at the physician and patient levels. Several factors are of special importance to women. Presence of prior gynecological malignancies may increase the risk of CRC in women. Furthermore, new studies have shown other factors such as obesity and smoking to increase the risk of CRC in women. This article highlights issues unique to women with regards to CRC and outlines special considerations for determining screening intervals in women, identifies factors that make screening more difficult in women, and reviews studies that identify preventative strategies which, together with screening, may reduce the burden of CRC.