Early life exposure to famine and colorectal cancer risk: a role for epigenetic mechanisms.
ABSTRACT: BACKGROUND: Exposure to energy restriction during childhood and adolescence is associated with a lower risk of developing colorectal cancer (CRC). Epigenetic dysregulation during this critical period of growth and development may be a mechanism to explain such observations. Within the Netherlands Cohort Study on diet and cancer, we investigated the association between early life energy restriction and risk of subsequent CRC characterized by the (promoter) CpG island methylation phenotype (CIMP). METHODOLOGY/PRINCIPAL FINDINGS: Information on diet and risk factors was collected by baseline questionnaire (n = 120,856). Three indicators of exposure were assessed: place of residence during the Hunger Winter (1944-45) and World War II years (1940-44), and father's employment status during the Economic Depression (1932-40). Methylation specific PCR (MSP) on DNA from paraffin embedded tumor tissue was performed to determine CIMP status according to the Weisenberger markers. After 7.3 years of follow-up, 603 cases and 4631 sub-cohort members were available for analysis. Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals for CIMP+ (27.7%) and CIMP- (72.3%) tumors according to the three time periods of energy restriction, adjusted for age and gender. Individuals exposed to severe famine during the Hunger Winter had a decreased risk of developing a tumor characterized by CIMP compared to those not exposed (HR 0.65, 95%CI: 0.45-0.92). Further categorizing individuals by an index of '0-1' '2-3' or '4-7' genes methylated in the promoter region suggested that exposure to the Hunger Winter was associated with the degree of promoter hypermethylation ('0-1 genes methylated' HR = 1.01, 95%CI:0.74-1.37; '2-3 genes methylated' HR = 0.83, 95% CI:0.61-1.15; '4-7 genes methylated' HR = 0.72, 95% CI:0.49-1.04). No associations were observed with respect to the Economic Depression and WWII years. CONCLUSIONS: This is the first study indicating that exposure to a severe, transient environmental condition during adolescence and young adulthood may result in persistent epigenetic changes that later influence CRC development.
Project description:Colorectal cancer (CRC) is a heterogeneous disease in terms of molecular carcinogenic pathways. Based on recent findings regarding the multiple serrated neoplasia pathway, we revised an eight-marker panel for a new CIMP classification system.1370 patients who received surgical resection for CRCs were classified into three CIMP subtypes (CIMP-N: 0-4 methylated markers, CIMP-P1: 5-6 methylated markers and CIMP-P2: 7-8 methylated markers). Our findings were validated in a separate set of high-risk stage II or stage III CRCs receiving adjuvant fluoropyrimidine plus oxaliplatin (n=950).A total of 1287/62/21 CRCs cases were classified as CIMP-N/CIMP-P1/CIMP-P2, respectively. CIMP-N showed male predominance, distal location, lower T, N category and devoid of BRAF mutation, microsatellite instability (MSI) and MLH1 methylation. CIMP-P1 showed female predominance, proximal location, advanced TNM stage, mild decrease of CK20 and CDX2 expression, mild increase of CK7 expression, BRAF mutation, MSI and MLH1 methylation. CIMP-P2 showed older age, female predominance, proximal location, advanced T category, markedly reduced CK20 and CDX2 expression, rare KRAS mutation, high frequency of CK7 expression, BRAF mutation, MSI and MLH1 methylation. CIMP-N showed better 5-year cancer-specific survival (CSS; HR=0.47; 95% CI: 0.28-0.78) in discovery set and better 5-year relapse-free survival (RFS; HR=0.50; 95% CI: 0.29-0.88) in validation set compared with CIMP-P1. CIMP-P2 showed marginally better 5-year CSS (HR=0.28, 95% CI: 0.07-1.22) in discovery set and marginally better 5-year RFS (HR=0.21, 95% CI: 0.05-0.92) in validation set compared with CIMP-P1.CIMP subtypes classified using our revised system showed different clinical outcomes, demonstrating the heterogeneity of multiple serrated precursors of CIMP-positive CRCs.
Project description:Previous studies have shown adverse effects of CpG island methylator phenotype (CIMP) on colorectal cancer (CRC) prognosis. However, sample sizes were often limited and only few studies were able to adjust for relevant molecular features associated with CIMP. The aim of this study was to investigate the impact of CIMP on CRC survival in a large population-based study with comprehensive adjustment.The CIMP status and other molecular tumour features were analysed in 1385 CRC patients diagnosed between 2003 and 2010. Detailed information were obtained from standardised personal interviews and medical records. During follow-up (median: 4.9 years), we assessed vital status, cause of death and therapy details. Cox proportional hazard regression models were used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of survival after CRC.The CIMP-H occurred more frequently in patients with older age, female gender, cancer in the proximal colon, BRAF mutation and microsatellite instability-high (MSI-H). However, CIMP status was not associated with CRC prognosis in CRC patients (HR=1.00; 95% CI=0.72-1.40 for overall survival; HR=0.96; 95% CI=0.65-1.41 for disease-specific survival) or in any of the subgroups. Although CIMP status was associated with the presence of MSI-H and BRAF mutation, the prognostic effects of MSI-H (HR=0.49; 95% CI=0.27-0.90) and BRAF mutation (HR=1.78; 95% CI=1.10-2.84) were independent of CIMP status. Similar benefit of chemotherapy was found for CRC outcomes in both the CIMP-low/negative group and the CIMP-high group.CpG island methylator phenotype was not associated with CRC prognosis after adjusting for other important clinical factors and associated mutations.
Project description:BACKGROUND:Results of previous studies on the association of the CpG island methylator phenotype (CIMP) with colorectal cancer (CRC) prognosis were inconsistent and mostly based on different CIMP definitions. The current study aimed to comprehensively investigate the associations between DNA methylation on genes previously used to define CIMP status with CRC survival. RESULTS:Patients with CRC followed up for a median of 5.2?years were divided into a study cohort (n?=?568) and a validation cohort (n =?308). DNA methylation was measured in tumor tissue using the Illumina Infinium HumanMethylation450 BeadChip and restricted to 43 genes used to define CIMP status in previous studies. Cox proportional hazard regression models were used to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI) of survival after CRC, including adjustment for tumor stage, microsatellite instability, and BRAF mutation status. In the study cohort, ten CpG sites were identified to be associated with CRC survival. Seven of these ten CpG sites were also associated with CRC survival in the validation cohort and were used to construct a prognostic score. CRC patients with a prognostic score of the lowest methylation level showed poorer disease-specific survival compared with patients with the highest methylation level in both the study cohort and the validation cohort (HR?=?3.11 and 95% CI?=?1.97-4.91, and HR?=?3.06 and 95% CI?=?1.71-5.45, respectively). CONCLUSIONS:A CpG panel consisting of seven CpG sites was found to be strongly associated with CRC survival, independent from important clinical factors and mutations associated with CIMP. Further studies are required to confirm these findings.
Project description:Abstract <h4>Background</h4> Colorectal cancer (CRC) is a heterogeneous disease that can develop via 3 major pathways: conventional, serrated, and alternate. We aimed to examine whether the risk factor profiles differ according to pathway-related molecular subtypes. <h4>Methods</h4> We examined the association of 24 risk factors with 4 CRC molecular subtypes based on a combinatorial status of microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and BRAF and KRAS mutations by collecting data from 2 large US cohorts. We used inverse probability weighted duplication-method Cox proportional hazards regression to evaluate differential associations across subtypes. <h4>Results</h4> We documented 1175 CRC patients with molecular subtype data: subtype 1 (n?=?498; conventional pathway; non-MSI-high, CIMP-low or negative, BRAF-wild-type, KRAS-wild-type), subtype 2 (n?=?138; serrated pathway; any MSI status, CIMP-high, BRAF-mutated, KRAS-wild-type), subtype 3 (n?=?367; alternate pathway; non-MSI-high, CIMP-low or negative, BRAF-wild-type, KRAS-mutated), and subtype 4 (n?=?172; other marker combinations). Statistically significant heterogeneity in associations with CRC subtypes was found for age, sex, and smoking, with a higher hazard ratio (HR) observed for the subtype 2 (HR per 10?years of age = 2.64, 95% CI = 2.13 to 3.26; HR for female = 2.65, 95% CI = 1.60 to 4.39; HR per 20-pack-year of smoking = 1.29, 95% CI = 1.14 to 1.45) than other CRC subtypes (all Pheterogeneity < .005). A stronger association was found for adiposity measures with subtype 1 CRC in men and subtype 3 CRC in women and for several dietary factors with subtype 1 CRC, although these differences did not achieve statistical significance at ?? level of .005. <h4>Conclusions</h4> Risk factor profiles may differ for CRC arising from different molecular pathways.
Project description:Colorectal cancer (CRC) is a heterogeneous disease that can develop via several pathways. Different CRC subtypes, identified based on tumor markers, have been proposed to reflect these pathways. We evaluated the significance of these previously proposed classifications to survival.Participants in the population-based Seattle Colon Cancer Family Registry were diagnosed with invasive CRC from 1998 through 2007 in western Washington State (N = 2706), and followed for survival through 2012. Tumor samples were collected from 2050 participants and classified into 5 subtypes based on combinations of tumor markers: type 1 (microsatellite instability [MSI]-high, CpG island methylator phenotype [CIMP] -positive, positive for BRAF mutation, negative for KRAS mutation); type 2 (microsatellite stable [MSS] or MSI-low, CIMP-positive, positive for BRAF mutation, negative for KRAS mutation); type 3 (MSS or MSI low, non-CIMP, negative for BRAF mutation, positive for KRAS mutation); type 4 (MSS or MSI-low, non-CIMP, negative for mutations in BRAF and KRAS); and type 5 (MSI-high, non-CIMP, negative for mutations in BRAF and KRAS). Multiple imputation was used to impute tumor markers for those missing data on 1-3 markers. We used Cox regression to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations of subtypes with disease-specific and overall mortality, adjusting for age, sex, body mass, diagnosis year, and smoking history.Compared with participants with type 4 tumors (the most predominant), participants with type 2 tumors had the highest disease-specific mortality (HR = 2.20, 95% CI: 1.47-3.31); subjects with type 3 tumors also had higher disease-specific mortality (HR = 1.32, 95% CI: 1.07-1.63). Subjects with type 5 tumors had the lowest disease-specific mortality (HR = 0.30, 95% CI: 0.14-0.66). Associations with overall mortality were similar to those with disease-specific mortality.Based on a large, population-based study, CRC subtypes, defined by proposed etiologic pathways, are associated with marked differences in survival. These findings indicate the clinical importance of studies into the molecular heterogeneity of CRC.
Project description:The presence or absence of MLH1 methylation may critically affect the heterogeneity of colorectal carcinoma (CRC) with the CpG island methylator phenotype (CIMP). Here, we investigated the differential characteristics of CIMP-high (CIMP-H) CRCs according to MLH1 methylation status. To further confirm the MLH1-dependent features in CIMP-H CRC, an independent analysis was performed using data from The Cancer Genome Atlas (TCGA). In our CIMP-H CRC samples, MLH1-methylated tumors were characterized by older patient age, proximal colonic location, mucinous histology, intense lymphoid reactions, RUNX3/SOCS1 promoter methylation, BRAF mutations, and microsatellite instability-high (MSI-H) status. By contrast, MLH1-unmethylated tumors were associated with earlier age of onset, increased distal colorectal localization, adverse pathologic features, and KRAS mutations. In the TCGA dataset, the MLH1-silenced CIMP-H CRC demonstrated proximal location, MSI-H status, hypermutated phenotype, and frequent BRAF mutations, but the MLH1-non-silenced CIMP-H CRC was significantly associated with high frequencies of KRAS and APC mutations. In conclusion, the differential nature of CIMP-H CRCs depends primarily on the MLH1 methylation status. Based on the current knowledge, the sessile serrated adenoma/polyp may be the major precursor of MLH1-methylated CIMP-H CRCs, whereas MLH1-unmethylated CIMP-H CRCs may develop predominantly from KRAS-mutated traditional serrated adenomas and less commonly from BRAF-mutated traditional serrated adenomas and/or sessile serrated adenomas/polyps.
Project description:OBJECTIVES:Cigarette smoking has been linked to somatic genetic and epigenetic aberrations, including CpG island methylator phenotype (CIMP)-high, microsatellite instability (MSI)-high and BRAF mutation. These molecular features have been associated with synchronous primary colorectal cancers (CRCs). Thus, we examined the hypothesis that smoking might be associated with the risk of synchronous CRCs. METHODS:Within the Health Professionals Follow-up Study and Nurses' Health Study, we examined the relationship of smoking and incidence of CRC according to tumor synchronicity, using duplication-method Cox proportional hazards regression analysis. RESULTS:We confirmed 1,981 solitary CRC and 45 synchronous CRC cases during follow-up of 134,305 individuals. CRC risk associated with smoking differed significantly by tumor synchronicity status (Pheterogeneity<0.001). When comparing current smokers with never smokers, multivariable hazard ratios (HR) were 5.27 (95% confidence interval (CI), 2.08-13.40) for synchronous CRCs and 0.97 (95% CI, 0.83-1.14) for solitary CRC. Similarly, differential associations were observed when examining cumulative pack-years smoked (Pheterogeneity=0.006). Smoking cessation for ?10 years relative to current smoking might reduce the risk of synchronous CRCs (multivariable HR=0.42; 95% CI, 0.19-0.95), but not solitary CRC (multivariable HR=1.10; 95% CI, 0.94-1.29; Pheterogeneity=0.001). Comparing current and former smokers with never smokers, multivariable HRs for synchronous CRCs were significantly higher than those of solitary CRC positive for either CIMP-high, MSI-high, or BRAF mutation (Pheterogeneity=0.002). CONCLUSIONS:Smoking is associated with an elevated risk of synchronous CRCs. Our data support a model where smoking contributes to an etiologic field effect that favors these somatic molecular alterations and the development of multiple primary tumors.
Project description:Most previous studies of the CpG island methylator phenotype (CIMP) in colorectal cancer (CRC) have been conducted on a relatively small numbers of CpG sites. In the present study we performed comprehensive DNA methylation profiling of CRC with the aim of characterizing CIMP subgroups.DNA methylation at 1,505 CpG sites in 807 cancer-related genes was evaluated using the Illumina GoldenGate methylation array in 28 normal colonic mucosa and 91 consecutive CRC samples. Methylation data was analyzed using unsupervised hierarchical clustering. CIMP subgroups were compared for various clinicopathological and molecular features including patient age, tumor site, microsatellite instability (MSI), methylation at a consensus panel of CpG islands and mutations in BRAF and KRAS.A total of 202 CpG sites were differentially methylated between tumor and normal tissue. Unsupervised hierarchical clustering of methylation data from these sites revealed the existence of three CRC subgroups referred to as CIMP-low (CIMP-L, 21% of cases), CIMP-mid (CIMP-M, 14%) and CIMP-high (CIMP-H, 65%). In comparison to CIMP-L tumors, CIMP-H tumors were more often located in the proximal colon and showed more frequent mutation of KRAS and BRAF (P<0.001).Comprehensive DNA methylation profiling identified three CRC subgroups with distinctive clinicopathological and molecular features. This study suggests that both KRAS and BRAF mutations are involved with the CIMP-H pathway of CRC rather than with distinct CIMP subgroups.
Project description:Colorectal cancer (CRC) is usually categorised as proximal or distal CRC. Recently, many researchers have tried to determine the molecular heterogeneity of CRCs along bowel subsites. However, the differential effects of the CpG island methylator phenotype (CIMP) and microsatellite instability (MSI) on the clinical outcome according to tumour location are not well-known.We analysed clinicopathologic and molecular characteristics, including CIMP, MSI, KRAS and BRAF mutations, in 734 CRCs according to bowel subsites. And the prognostic value of CIMP and MSI was analysed according to tumour location.We found a linear increase of female predominance, T, N category, stage, differentiation, absence of luminal necrosis, tumour -infiltrating lymphocytes, Crohn's-like lymphoid reaction, serration and mucin production from the rectum to caecum. CpG island methylator phenotype -high and MSI-high gradually increased from the rectum to caecum. CpG island methylator phenotype is a poor prognostic factor of overall survival (hazard ratio (HR): 4.13, 95% confidence interval (CI): 1.27-13.46) and disease-free survival (HR: 2.90, 95% CI: 1.04-8.08) in rectal cancers.Clinicopathologic and molecular profiles of CRCs gradually change along bowel subsites, and the prognostic implication of CIMP is different according to tumour location.
Project description:The CpG island methylator phenotype (CIMP) is a major molecular pathway in colorectal cancer. Approximately 25% to 60% of CIMP tumors are microsatellite unstable (MSI-H) due to DNA hypermethylation of the MLH1 gene promoter. Our aim was to determine if the distributions of clinicopathologic factors in CIMP-positive tumors with MLH1 DNA methylation differed from those in CIMP-positive tumors without DNA methylation of MLH1.We assessed the associations between age, sex, tumor-site, MSI status BRAF and KRAS mutations, and family colorectal cancer history with MLH1 methylation status in a large population-based sample of CIMP-positive colorectal cancers defined by a 5-marker panel using unconditional logistic regression to assess the odds of MLH1 methylation by study variables.Subjects with CIMP-positive tumors without MLH1 methylation were significantly younger, more likely to be male, and more likely to have distal colon or rectal primaries and the MSI-L phenotype. CIMP-positive MLH1-unmethylated tumors were significantly less likely than CIMP-positive MLH1-methylated tumors to harbor a BRAF V600E mutation and significantly more likely to harbor a KRAS mutation. MLH1 methylation was associated with significantly better overall survival (HR, 0.50; 95% confidence interval, 0.31-0.82).These data suggest that MLH1 methylation in CIMP-positive tumors is not a completely random event and implies that there are environmental or genetic determinants that modify the probability that MLH1 will become methylated during CIMP pathogenesis.MLH1 DNA methylation status should be taken into account in etiologic studies.