Age-related methylation in normal colon mucosa differs between the proximal and distal colon in patients who underwent colonoscopy

The human colon: Evidence for degenerative changes during aging and the physiological consequences

BACKGROUND

The incidence of constipation increases among the elderly (>65 years), while abdominal pain decreases. Causes include changes in lifestyle (e.g., diet and reduced exercise), disease and medications affecting gastrointestinal functions. Degenerative changes may also occur within the colo-rectum. However, most evidence is from rodents, animals with relatively high rates of metabolism and accelerated aging, with considerable variation in time course. In humans, cellular and non-cellular changes in the aging intestine are poorly investigated.

PURPOSE

To examine all available studies which reported the effects of aging on cellular and tissue functions of human isolated colon, noting the region studied, sex and age of tissue donors and study size. The focus on human colon reflects the ability to access full-thickness tissue over a wide age range, compared with other gastrointestinal regions. Details are important because of natural human variability. We found age-related changes within the muscle, in the enteric and nociceptor innervation, and in the submucosa. Some involve all regions of colon, but the ascending colon appears more vulnerable. Changes can be cell- and sublayer-dependent. Mechanisms are unclear but may include development of "senescent-like" and associated inflammaging, perhaps associated with increased mucosal permeability to harmful luminal contents. In summary, reduced nociceptor innervation can explain diminished abdominal pain among the elderly. Degenerative changes within the colon wall may have little impact on symptoms and colonic functions, because of high "functional reserve," but are likely to facilitate the development of constipation during age-related challenges (e.g., lifestyle, disease, and medications), now operating against a reduced functional reserve.

RNAM EXPRESSION AND DNA METHYLATION OF DKK2 GENE IN COLORECTAL CÂNCER

BACKGROUND

Colorectal cancer is the third most common neoplasm in the world. Methylation of tumor related genes in CpG islands can cause gene silencing and been involved in the development of cancer. The potential role of DKK2 as a biomarker for early diagnosis of colorectal cancer remains unclear.

OBJECTIVE

The aim of the study was to evaluate the profile of methylation and RNAm expression of DKK2 as potential predictors of colorectal cancer diagnosis and prognosis.

METHODS

Expression of mRNAs encoding DKK2 in 35 colorectal cancer tissues was quantified using real-time polymerase chain reaction analysis. The DNA methylation was studied by high resolution melting analysis. The general characteristics of the patients were collected. DKK2 methylation and expression were compared to clinical, pathological aspects and overall survival.

RESULTS

Among the 35 patients studied, 18 were male, 10 were on right colon and 25 on left colon. Among the 20 patients with high hypermethylation, 15 of them had mRNA low expression of DKK2. There was no significant association between DKK2 promoter methylation and mRNA DKK2 expression and clinical or pathological features. DKK2 promoter methylation (P=0.154) and DKK2 RNA expression (P=0.345) did not show significant correlation with overall survival.

CONCLUSION

DKK2 promoter methylation and DKK2 RNA status appear to be biomarkers of cancer diagnosis but not predictors of prognosis.

Dietary B vitamin and methionine intakes and risk for colorectal cancer: a case-control study in China

B vitamins (including folate, vitamin B2, vitamin B6 and vitamin B12) and methionine are essential for methylation reactions, nucleotide synthesis, DNA stability and DNA repair. However, epidemiological evidence among Chinese populations is limited. The objective of this study was to evaluate B vitamins and methionine in relation to colorectal cancer risk in a Chinese population. A case-control study was conducted from July 2010 to April 2019. A total of 2502 patients with colorectal cancer were recruited along with 2538 age- (5-year interval) and sex-matched controls. Dietary data were collected using a validated FFQ. Multivariable logistic regression was used to assess OR and 95 % CI. The intake of folate, vitamin B2, vitamin B6 and vitamin B12 was inversely associated with colorectal cancer risk. The multivariable OR for the highest quartile v. the lowest quartile were 0·62 (95 % CI 0·51, 0·74; Ptrend < 0·001) for folate, 0·46 (95 % CI 0·38, 0·55; Ptrend < 0·001) for vitamin B2, 0·55 (95 % CI 0·46, 0·76; Ptrend < 0·001) for vitamin B6 and 0·72 (95 % CI 0·60, 0·86; Ptrend < 0·001) for vitamin B12. No statistically significant association was found between methionine intake and colorectal cancer risk. Stratified analysis by sex showed that the inverse associations between vitamin B12 and methionine intake and colorectal cancer risk were found only among women. This study indicated that higher intake of folate, vitamin B2, vitamin B6 and vitamin B12 was associated with decreased risk of colorectal cancer in a Chinese population.

DNA methylation patterns in ulcerative colitis-associated cancer: a systematic review

BACKGROUND

Evidence points to the role of DNA methylation in ulcerative colitis (UC)-associated cancer (UCC), the most serious complication of ulcerative colitis. A better understanding of the etiology of UCC may facilitate the development of new therapeutic targets and help to identify biomarkers of the disease risk.

METHODS

A search was performed in three databases following PRISMA protocol. DNA methylation in UCC was compared with sporadic colorectal cancer (SCRC), and individual genes differently methylated in UCC identified.

RESULTS

While there were some similarities in the methylation patterns of UCC compared with SCRC, generally lower levels of hypermethylation in promoter regions of individual genes was evident in UCC. Certain individual genes are, however, highly methylated in colitis-associated cancer: RUNX3, MINT1, MYOD and p16 exon1 and the promoter regions of EYA4 and ESR.

CONCLUSION

Patterns of DNA methylation differ between UCC and SCRC. Seven genes appear to be promising putative biomarkers.

Myeloperoxidase expression in human colonic mucosa is related to systemic oxidative balance in healthy subjects

OBJECTIVES

To improve understanding of the preclinical stage of colonic inflammation by exploring the existence of a link between early inflammatory changes in the colonic mucosa and the systemic redox balance.

METHODS

Clinical characteristics, a fasting blood draw, and mucosal biopsies from the right, left, and sigmoid-rectum colonic tracts collected from 28 healthy individuals (14/14 males/females) who underwent colonoscopy. Myeloperoxidase (MPO) positive cells infiltrating colonic mucosa specimens were assessed by immunohistochemistry, and patients divided into high or low MPO expressing cells/optical field groups (MPO^high or MPO^low, respectively).The systemic oxidative balance has been studied through derived-Reactive Oxygen Metabolites (d-ROMs), Biological Antioxidant Potential (BAP), and Lipoperoxide-cholesterol Oxidizing (LP-CHOLOX) tests on serum.

RESULTS

MPO^high patients demonstrated an increased systemic oxidative stress compared to MPO^low individuals (P = 0.035), especially when MPO is referred to the left-sided colonic mucosa (P = 0.007). MPO^low subjects in the sigmoid-rectum showed a significant higher antioxidant capacity in the serum (P < 0.02). Sex-specific differences in MPO expression (male and female: 4.6 ± 3.2 and 2.6 ± 1.5 MPO-positive cells/optical field, respectively, P = 0.044), and a decreasing gradient in MPO expression moving from the cecum to the rectum (ascendant, descendant, and sigmoid-rectum: 3.7 ± 2.8, 3.1 ± 1.7, and 1.4 ± 0.5, respectively, P = 0.012) were also found and discussed.

DISCUSSION

The study is the first demonstrating a connection between systemic redox balance and MPO expression in the colonic mucosa, according to the colonic tract and patient gender. Further research evaluating the MPO expression in the human colon and its relationship with pathological conditions could benefit from these results.

Aging related methylation influences the gene expression of key control genes in colorectal cancer and adenoma

AIM

To analyze colorectal carcinogenesis and age-related DNA methylation alterations of gene sequences associated with epigenetic clock CpG sites.

METHODS

In silico DNA methylation analysis of 353 epigenetic clock CpG sites published by Steve Horvath was performed using methylation array data for a set of 123 colonic tissue samples [64 colorectal cancer (CRC), 42 adenoma, 17 normal; GEO accession number: GSE48684]. Among the differentially methylated age-related genes, secreted frizzled related protein 1 (SFRP1) promoter methylation was further investigated in colonic tissue from 8 healthy adults, 19 normal children, 20 adenoma and 8 CRC patients using bisulfite-specific PCR followed by methylation-specific high resolution melting (MS-HRM) analysis. mRNA expression of age-related “epigenetic clock” genes was studied using Affymetrix HGU133 Plus2.0 whole transcriptome data of 153 colonic biopsy samples (49 healthy adult, 49 adenoma, 49 CRC, 6 healthy children) (GEO accession numbers: GSE37364, GSE10714, GSE4183, GSE37267). Whole promoter methylation analysis of genes showing inverse DNA methylation-gene expression data was performed on 30 colonic samples using methyl capture sequencing.

RESULTS

Fifty-seven age-related CpG sites including hypermethylated PPP1R16B, SFRP1, SYNE1 and hypomethylated MGP, PIPOX were differentially methylated between CRC and normal tissues (P < 0.05, Δβ≥ 10%). In the adenoma vs normal comparison, 70 CpG sites differed significantly, including hypermethylated DKK3, SDC2, SFRP1, SYNE1 and hypomethylated CEMIP, SPATA18 (P < 0.05, Δβ≥ 10%). In MS-HRM analysis, the SFRP1 promoter region was significantly hypermethylated in CRC (55.0% ± 8.4 %) and adenoma tissue samples (49.9% ± 18.1%) compared to normal adult (5.2% ± 2.7%) and young (2.2% ± 0.7%) colonic tissue (P < 0.0001). DNA methylation of SFRP1 promoter was slightly, but significantly increased in healthy adults compared to normal young samples (P < 0.02). This correlated with significantly increased SFRP1 mRNA levels in children compared to normal adult samples (P < 0.05). In CRC tissue the mRNA expression of 117 age-related genes were changed, while in adenoma samples 102 genes showed differential expression compared with normal colonic tissue (P < 0.05, logFC > 0.5). The change of expression for several genes including SYNE1, CLEC3B, LTBP3 and SFRP1, followed the same pattern in aging and carcinogenesis, though not for all genes (e.g., MGP).

CONCLUSION

Several age-related DNA methylation alterations can be observed during CRC development and progression affecting the mRNA expression of certain CRC- and adenoma-related key control genes.

LINE-1 Methylation Status Correlates Significantly to Post-Therapeutic Recurrence in Stage III Colon Cancer Patients Receiving FOLFOX-4 Adjuvant Chemotherapy

Background

Methylation levels of long interspersed nucleotide elements (LINE-1) are representative of genome-wide methylation status and crucial in maintaining genomic stability and expression. Their prognostic impact on colon cancer patients receiving adjuvant chemotherapy has not been well established. We evaluated the association between LINE-1 methylation status and clinicopathologic features and postoperative oncological outcomes in stage III colon cancer patients.

Materials and Methods

129 UICC stage III colon cancer patients who had received radical resection and FOLFOX adjuvant chemotherapy were enrolled. Global methylation was estimated by analyzing tumor LINE-1 methylation status using bisulfite-polymerase chain reaction (PCR) and pyrosequencing assay. Demographics, clinicopathological data, and postoperative outcomes were recorded by trained abstractors. Outcome measurements included postoperative recurrence and disease-free survival. Univariate, multivariate, and survival analyses were conducted to identify prognostic factors of oncological outcomes.

Results

The LINE-1 methylation of all 129 patients was measured on a 0–100 scale (mean 63.3; median 63.7, standard deviation 7.1), LINE-1 hypomethylation was more common in patients aged 65 years and above (61.7%±7.6% vs. 64.6±6.4, p=0.019) and those with post-therapeutic recurrence (61.7±7.4 vs 64.3±6.7, p=0.041). Considering risk adjustment, LINE-1 hypomethylation was found to be an independent risk factor of post-therapeutic recurrence (Adjusted OR=14.1, p=0.012). Kaplan-Meier analysis indicated that patients in the low methylation group had shorter period of disease free survival (p=0.01). In a stratified analysis that included 48 patients with post-therapeutic recurrence, it was found that those who experienced shorter period of disease free survival (≦6 months) appeared to have lower LINE-1 methylation levels than patients who reported of recurrence after 6 months (56.68±15.75 vs. 63.55±7.57, p=0.041)

Conclusion

There was a significantly greater risk of early postoperative recurrence and a shorter period of disease-free survival in Stage III colon cancer patients exhibiting LINE-1 hypomethylation status after being treated with radical resection and FOLFOX chemotherapy.

Modulation of age- and cancer-associated DNA methylation change in the healthy colon by aspirin and lifestyle

BACKGROUND

Aberrant DNA methylation in gene promoters is associated with aging and cancer, but the circumstances determining methylation change are unknown. We investigated the impact of lifestyle modulators of colorectal cancer (CRC) risk on the stability of gene promoter methylation in the colonic mucosa.

METHODS

We measured genome-wide promoter CpG methylation in normal colon biopsies (n = 1092) from a female screening cohort, investigated the interaction of lifestyle factors with age-dependent increase in methylation with log-linear multivariable regression, and related their modifying effect to hypermethylation in CRC. All statistical tests were two-sided.

RESULTS

Of 20025 promoter-associated CpGs analyzed, 1713 showed statistically significant age-dependent methylation gains. Fewer CpGs acquired methylation in users of aspirin (≥ 2 years) and hormonal replacement therapy (HRT age ≥ 50 years) compared with nonusers (43 vs 1355; 1 vs1377, respectively), whereas more CpGs were affected in smokers (≥ 20 years) and individuals with a body mass index (BMI) of 25 kg/m(2) and greater compared with control groups (180 vs 39; 554 vs 144, respectively). Fifty percent of the CpGs showing age-dependent methylation were found hypermethylated in CRC (odds ratio [OR] = 20; 95% confidence interval [CI] = 18 to 23; P < 2 × 10(-16)). These loci gained methylation with a higher median rate compared with age-only methylated sites (P = 2 × 10(-76)) and were enriched for polycomb regions (OR = 3.67). Importantly, aspirin (P < .001) and HRT use (P < .001) reduced the methylation rate at these cancer-related genes, whereas smoking (P < .001) and high BMI (P = .004) increased it.

CONCLUSIONS

Lifestyle, including aspirin use, modulates age-associated DNA methylation change in the colonic epithelium and thereby impacts the evolution of cancer methylomes.

DNA methylation-associated colonic mucosal immune and defense responses in treatment-naïve pediatric ulcerative colitis

Inflammatory bowel diseases (IBD) are emerging globally, indicating that environmental factors may be important in their pathogenesis. Colonic mucosal epigenetic changes, such as DNA methylation, can occur in response to the environment and have been implicated in IBD pathology. However, mucosal DNA methylation has not been examined in treatment-naïve patients. We studied DNA methylation in untreated, left sided colonic biopsy specimens using the Infinium HumanMethylation450 BeadChip array. We analyzed 22 control (C) patients, 15 untreated Crohn’s disease (CD) patients, and 9 untreated ulcerative colitis (UC) patients from two cohorts. Samples obtained at the time of clinical remission from two of the treatment-naïve UC patients were also included into the analysis. UC-specific gene expression was interrogated in a subset of adjacent samples (5 C and 5 UC) using the Affymetrix GeneChip PrimeView Human Gene Expression Arrays. Only treatment-naïve UC separated from control. One-hundred-and-twenty genes with significant expression change in UC (> 2-fold, P &lt; 0.05) were associated with differentially methylated regions (DMRs). Epigenetically associated gene expression changes (including gene expression changes in the IFITM1, ITGB2, S100A9, SLPI, SAA1, and STAT3 genes) were linked to colonic mucosal immune and defense responses. These findings underscore the relationship between epigenetic changes and inflammation in pediatric treatment-naïve UC and may have potential etiologic, diagnostic, and therapeutic relevance for IBD.

Epigenetic susceptibility factors for prostate cancer with aging

BACKGROUND

Increasing age is a significant risk factor for prostate cancer. The prostate is exposed to environmental and endogenous stress that may underlie this remarkable incidence. DNA methylation, genomic imprinting, and histone modifications are examples of epigenetic factors known to undergo change in the aging and cancerous prostate. In this review we examine the data linking epigenetic alterations in the prostate with aging to cancer development.

METHODS

An online search of current and past peer reviewed literature on epigenetic changes with cancer and aging was performed. Relevant articles were analyzed.

RESULTS

Epigenetic changes are responsible for modifying expression of oncogenes and tumor suppressors. Several of these changes may represent a field defect that predisposes to cancer development. Focal hypermethylation occurs at CpG islands in the promoters of certain genes including GSTP1, RARβ2, and RASSF1A with both age and cancer, while global hypomethylation is seen in prostate cancer and known to occur in the colon and other organs. A loss of genomic imprinting is responsible for biallelic expression of the well-known Insulin-like Growth Factor 2 (IGF2) gene. Loss of imprinting (LOI) at IGF2 has been documented in cancer and is also known to occur in benign aging prostate tissue marking the presence of cancer. Histone modifications have the ability to dictate chromatin structure and direct gene expression.

CONCLUSIONS

Epigenetic changes with aging represent molecular mechanisms to explain the increased susceptibly of the prostate to develop cancer in older men. These changes may provide an opportunity for diagnostic and chemopreventive strategies given the epigenome can be modified.

The topography of DNA methylation in the non-neoplastic colonic mucosa surrounding colorectal cancers

The degree of gene hypermethylation in non-neoplastic colonic mucosa (NNCM) is a potentially important event in the development of colorectal cancer (CRC), particularly for the subgroup with a CpG island methylator phenotype (CIMP). In this study, we aimed to use an unbiased and high-throughput approach to evaluate the topography of DNA methylation in the non-neoplastic colonic mucosa (NNCM) surrounding colorectal cancer (CRC). A total of 61 tissue samples comprising 53 NNCM and 8 tumor samples were obtained from hemicolectomy specimens of two CRC patients (Cases 1 and 2). NNCM was stripped from the underlying colonic wall and samples taken at varying distances from the tumor. The level of DNA methylation in NNCM and tumor tissues was assessed at 1,505 CpG sites in 807 cancer-related genes using Illumina GoldenGate® methylation arrays. Case 1 tumor showed significantly higher levels of methylation compared to surrounding NNCM samples (P < 0.001). The average level of methylation in NNCM decreased with increasing distance from the tumor (r = -0.418; P = 0.017), however this was not continuous and "patches" with higher levels of methylation were observed. Case 2 tumor was less methylated than Case 1 tumor (average β-value 0.181 vs. 0.415) and no significant difference in the level of methylation was observed in comparison to the surrounding NNCM. No evidence was found for a diminishing gradient of methylation in the NNCM surrounding CRC with a high level of methylation. Further work is required to determine whether CIMP+ CRC develop from within "patches" of NCCM that display high levels of methylation.

DNA demethylation in normal colon tissue predicts predisposition to multiple cancers

Some colon cancer (CC) patients present synchronous cancers at diagnosis and others develop metachronous neoplasms, but the risk factors are unclear for non-hereditary CC. We showed previously that global DNA demethylation increased with aging and correlated with genomic damage in CC, and we show now that preferentially associates to CCs with wild-type p53. This study aimed to elucidate the extent of DNA hypomethylation in patients with single and multiple CC, its relationship with aging, and its potential as predictive tool. We compared by real-time methylation-specific PCR the relative demethylation level (RDL) of long interspersed nucleotide element-1 (LINE-1) sequences in matched cancer tissues and non-cancerous colonic mucosa (NCM) from patients with single and multiple right-sided CCs. Although no RDL difference was found in NCM from single CC patients and healthy volunteers (P=0.5), there was more demethylation (higher RDL) in NCM from synchronous cancer patients (P=1.1 × 10(-5)) multiple CCs also were more demethylated than single CCs (P=0.0014). High NCM demethylation was predictive for metachronous neoplasms (P=0.003). In multivariate logistic regression analyses RDL was the only independent predictor for metachronous (P=0.02) and multiple (P=4.9 × 10(-5)) tumors. The higher LINE-1 demethylation in NCM from patients with multiple (synchronous and metachronous) tumors (P=9.6 × 10(-7)) was also very significant in patients with tumors without (P=3.8 × 10(-6)), but not with (P=0.16) microsatellite instability. NCM demethylation increased with aging in patients with single tumors, but decreased in those with multiple tumors. Moreover, the demethylation difference between patients with single vs multiple tumors appeared higher in younger (P=3.6 × 10(-4)) than in older (P=0.0016) patients. These results predict that LINE-1 hypomethylation in NCM can be used as an epigenetic predictive biomarker for multiple CC risk. The stronger association of demethylation in NCM with multiple CC risk from younger patients also suggests an inherited predisposition for the apparent field cancerization effect of somatic demethylation.

Effect of ageing on colonic mucosal regeneration

The physiologic and pathologic cellular and molecular changes occurring with age in the human colon affect both the inflammatory process leading to mucosal injury and the regenerative capacity of the epithelium. On the one hand, age-related telomere shortening and inflamm-ageing may lead to the development of colonic inflammation, which results in epithelial damage. On the other hand, the altered migration and function of regenerative stem cells, the age-related methylation of mucosal healing-associated genes, together with the alterations of growth factor signaling with age, may be involved in delayed mucosal regeneration. The connections of these alterations to the process of ageing are not fully known. The understanding and custom-tailored modification of these mechanisms are of great clinical importance with regard to disease prevention and modern therapeutic strategies. Here, we aim to summarize the age-related microscopic and molecular changes of the human colon, as well as their role in altered mucosal healing.

Clinical implications of DNA methylation in hepatocellular carcinoma

BACKGROUND

Epigenetics is a rapidly evolving field of genetic study applicable to nearly every aspect of genome-related research. The importance of epigenetics has been recognised in human hepatocellular carcinoma (HCC). Changes in DNA methylation patterns, including global hypomethylation and promoter hypermethylation, are thought to be early events in hepatocarcinogenesis.

OBJECTIVES

This review aimed to summarise the role of epigenetics in HCC, to describe the mechanisms of epigenetic changes in HCC and to examine the clinical relevance of epigenetics in HCC.

METHODS

This review examines the role of CpG-rich regions and DNA methylation, and describes an epigenetic model of cancer, tumour type-specific methylation, the relationships among methylation, cirrhosis and hepatocarcinogenesis, and the role of DNA methylation in HCC. The clinical implications of epigenetics in HCC are discussed.

RESULTS

A multivariate predictor model based on traditional clinical factors and DNA methylation profile may have important applications in the early detection of neoplastic transformation in populations at high risk for HCC. CpG methylation may be valuable in HCC prognostics. DNA methylation profiles may enable clinical prediction in pre-therapy patient biopsies, paraffin-embedded samples or plasma DNA.

CONCLUSIONS

Epigenetic changes and profiles may correlate to the biological behaviour of tumours and clinical outcome of HCC patients. The use of DNA methylation profiles as a surrogate biomarker remains an active area of clinical cancer research.

Association between folate levels and CpG Island hypermethylation in normal colorectal mucosa

Gene-specific promoter methylation of several genes occurs in aging normal tissues and may predispose to tumorigenesis. In the present study, we investigate the association of blood folate levels and dietary and lifestyle factors with CpG island (CGI) methylation in normal colorectal mucosa. Subjects were enrolled in a multicenter chemoprevention trial of aspirin or folic acid for the prevention of large bowel adenomas. We collected 1,000 biopsy specimens from 389 patients, 501 samples from the right colon and 499 from the rectum at the follow-up colonoscopy. We measured DNA methylation of estrogen receptor alpha (ERα) and secreted frizzled related protein-1 (SFRP1), using bisulfite pyrosequencing. We used generalized estimating equations regression analysis to examine the association between methylation and selected variables. For both ERα and SFRP1, percentage methylation was significantly higher in the rectum than in the right colon (P = 0.001). For each 10 years of age, we observed a 1.7% increase in methylation level for ERα and a 2.9% increase for SFRP1 (P < 0.0001). African Americans had a significantly lower level of ERα and SFRP1 methylation than Caucasians and Hispanics. Higher RBC folate levels were associated with higher levels of both ERα (P = 0.03) and SFRP1 methylation (P = 0.01). Our results suggest that CGI methylation in normal colorectal mucosa is related to advancing age, race, rectal location, and RBC folate levels. These data have important implications regarding the safety of supplementary folate administration in healthy adults, given the hypothesis that methylation in normal mucosa may predispose to colorectal neoplasia.

DNA methylation in the rectal mucosa is associated with crypt proliferation and fecal short-chain fatty acids

BACKGROUND

DNA methylation varies throughout the normal colorectal mucosa and DNA methylation in normal appearing mucosa is associated with serrated and adenomatous neoplasia elsewhere within the colorectum.

AIMS

The purpose of this study was to measure luminal chemistry, rectal proliferation and mucosal DNA methylation and thus determine whether regional and pathological patterns of DNA methylation could be explained by luminal and epithelial factors.

METHODS

Twenty healthy subjects had normal rectal mucosal biopsies and a 24-h fecal collection. Rectal biopsies were analyzed for epithelial proliferation (Ki67 immunohistochemistry) and DNA methylation at 17 different markers, including "type A" markers (ESR1, GATA5, HIC1, HPP1, SFRP1), "type C" markers (MGMT, MLH1, CDKN2A, MINT1, MINT2, MINT31, IGF2, CACNA1G, NEUROG1, SOCS1, RUNX3), and LINE-1. Fecal analysis included short-chain fatty acids (SCFA), pH and ammonia. Mean "type A" and CIMP panel methylation Z-scores were calculated.

RESULTS

Rectal proliferation was significantly correlated with methylation at ESR1 (ρ = 0.81, P = 0.003) and GATA5 (ρ = 0.78, P = 0.012). LINE-1 methylation was 71.7 vs. 74.1%, in patients with "low" and "high" fecal total SCFA concentration (defined by the median value), respectively (P = 0.0019). On multivariate linear regression "type A" methylation was independently associated with rectal proliferation (P = 0.001). LINE-1 methylation was directly associated with rectal proliferation (P = 0.038) and total fecal SCFA concentration (P = 0.002), and inversely associated with fecal NH(3) concentrations (P = 0.003).

CONCLUSIONS

DNA methylation in normal rectal mucosa is associated with crypt proliferation and fecal SCFA concentration. These associations may help to explain regional differences in DNA methylation as well as providing a possible link between the colorectal lumen and carcinogenesis.

Antioxidant and DNA methylation-related nutrients and risk of distal colorectal cancer

OBJECTIVE

To investigate the relationship between antioxidant nutrients (vitamins C and E, beta-carotene, selenium) and DNA methylation-related nutrients (folate, vitamins B6 and B12) and distal colorectal cancer risk in whites and African Americans and to examine intakes from food only versus total (food plus dietary supplements) intakes.

METHODS

Data are from the North Carolina Colon Cancer Study-Phase II, a case-control study of 945 distal colorectal cancer (including sigmoid, rectosigmoid, and rectum) cases and 959 controls. In-person interviews captured usual dietary intake and various covariates. Multivariate logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI).

RESULTS

High intakes of each antioxidant and DNA methylation-related nutrient were significantly associated with lower risk in whites. In African Americans, the highest category of selenium from food only had a marginally significant inverse association with distal colorectal cancer risk (Q4 vs. Q1 OR: 0.55, 95% CI 0.29-1.02). Supplements did not provide additional risk reduction beyond intakes from food.

CONCLUSIONS

Our findings provide evidence that antioxidant and DNA methylation-related nutrients may lower the risk of distal colorectal cancer in whites, and selenium may lower risk in African Americans. Optimal micronutrient intakes from food alone may be more beneficial than supplementation.

Regulation of the colonic vitamin D system for prevention of tumor progression: an update

A compromised vitamin D status and nutritional calcium deficit are linked with sporadic colorectal cancer incidence. 25(OH)D3 serum concentration is a major determinant of 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) synthesis in colonic mucosa, which expresses the vitamin D receptor and both the synthesizing (CYP27B1) and catabolic (CYP24A1) hydroxylases. Receptor-bound, 1,25(OH)2D3 regulates proliferation, differentiation and apoptosis in an autocrine/paracrine manner. During early malignancy 1,25(OH)2D3 synthesis is often enhanced to counteract hyperproliferation. In many advanced tumors, vitamin D catabolism surpasses synthesis. In vivo, expression and activity of CYP27B1 and vitamin D receptor are stimulated by (phyto)estrogens. Conversely, low nutritional calcium and folate enhance vitamin D catabolism. These insights could explain the lower colorectal cancer incidence in females, the chemopreventive potency of vitamin D and calcium against colorectal cancer, and the benefit of nutritional folate as a methyl donor for epigenetic regulation of the vitamin D system.