Laura A. E. Hughes

The CpG island methylator phenotype in colorectal cancer: Progress and problems

In recent years, attention has focused on the biology and potential clinical importance of the CpG island methylator phenotype (CIMP) in colorectal cancer (CRC). While it is generally well accepted that etiologically and clinically distinct subgroups exist in this disease, a precise definition of CIMP remains to be established. Here, we summarize existing literature that documents the prevalence of CIMP in CRC, with particular attention to the various methods and definitions used to classify a tumor as CIMP positive. Through a systematic review on both case-series and population based studies, we examined only original research articles reporting on sporadic CRC and/or adenomas in unselected cases. Forty-eight papers published between January 1999 and August 2011 met the inclusion criteria. We describe the use of multiple gene panels, marker threshold values, and laboratory techniques which results in a wide range in the prevalence of CIMP. Because there is no universal standard or consensus on quantifying the phenotype, establishing its true prevalence is a challenge. This bottleneck is becoming increasingly evident as molecular pathological epidemiology continues to offer possibilities for clear answers regarding environmental risk factors and disease trends. For the first time, large, unselected series of cases are available for analysis, but comparing populations and pooling data will remain a challenge unless a universal definition of CIMP and a consensus on analysis can be reached, and the primary cause of CIMP identified.

Early life exposure to famine and colorectal cancer risk: A role for epigenetic mechanisms

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 fathers 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.

Body Size, Physical Activity and Risk of Colorectal Cancer with or without the CpG Island Methylator Phenotype (CIMP)

Background We investigated how body size and physical activity influence the risk of the CpG island methylator phenotype (CIMP) in colorectal cancer (CRC). Methods In the Netherlands Cohort Study (n = 120,852), risk factors were self-reported at baseline in 1986. After 7.3 years of follow-up, 603 cases and 4,631 sub-cohort members were available. CIMP status according to the Weisenberger markers was determined using methylation specific PCR on DNA from paraffin embedded tumor tissue. Hazard rate ratios (HR) and 95% confidence intervals for CIMP (27.7%) and non-CIMP (72.3%) tumors were calculated according to BMI, BMI at age 20, BMI change, trouser/skirt size, height, and physical activity. Results BMI modeled per 5 kg/m2 increase was associated with both CIMP and non-CIMP tumors, however, HRs were attenuated when additionally adjusted for trouser/skirt size. Trouser/skirt size, per 2 size increase, was associated with both tumor subtypes, even after adjustment for BMI (CIMP HR: 1.20, 95%CI: 1.01–1.43; non-CIMP HR: 1.14, 95%CI: 1.04–1.28). Height per 5 cm was associated with both tumor sub-types, but HRs were attenuated when adjusted for body weight. BMI at age 20 was positively associated with increased risk of CIMP tumors and the association was significantly less pronounced for non-CIMP tumors (P-heterogeneity = 0.01). Physical activity was inversely associated with both subtypes, but a dose-response association was observed only for non-CIMP tumors (P-trend = 0.02). Conclusions Body size, especially central adiposity, may increase the risk of both CIMP and non-CIMP tumors. Body fat at young age may differentially influence risk. Physical activity appears to decrease the risk of CRC regardless of these molecular subtypes.

A novel classification of colorectal tumors based on microsatellite instability, the CpG island methylator phenotype and chromosomal instability: implications for prognosis

BACKGROUND We studied the overlap between the major (epi)genomic events microsatellite instability (MSI), the CpG island methylator phenotype (CIMP) and chromosomal instability (CIN) in colorectal cancer (CRC), and whether specific (epi)genotypes were associated with CRC-related deaths. PATIENTS AND METHODS Molecular analyses using tumor DNA were successful in 509 CRC cases identified within the Netherlands Cohort Study in the period 1989-1993. Follow-up for the vital status until May 2005 was 100%. RESULTS MSI (12.6%), CIMP-only (5.3%), CIMP + CIN (13.4%), CIN-only (58.2%) and triple-negative tumors (10.6%) differed significantly regarding tumor localization, differentiation grade, initial adjuvant therapy (AT) use and genetic characteristics (P ≤ 0.03). CIMP-only, CIMP + CIN and triple-negative tumors, compared with CIN-only tumors, were significantly associated with a 3.67, 2.44 and 3.78-fold risk of CRC-related deaths after 2-year follow-up (95% confidence intervals, CIs, 1.70-7.91, 1.35-4.41 and 1.97-7.25, respectively), but not after late follow-up. MSI tumors were borderline significantly associated with a 0.40-fold risk of CRC-related deaths after late follow-up (95% CI 0.15-1.03). CONCLUSION(S) This is the first study to show that specific (epi)genotypes may hold a differential prognostic value that may vary over time. Although no specific treatment data were available, an explanation for the differential findings over time might be that (epi)genotypes modify therapy response.

Physical Activity, Occupational Sitting Time, and Colorectal Cancer Risk in the Netherlands Cohort Study

We investigated occupational energy expenditure and sitting time in the longest held job (in men only), nonoccupational physical activity, and former sports participation in relation to colorectal cancer endpoints. The Netherlands Cohort Study includes 120,852 participants who completed a self-administered questionnaire in 1986 when they were aged 55-69 years. By 2002, 1,819 male and 1,366 female colorectal cancer cases were available for case-cohort analyses. In men, higher occupational energy expenditure levels and fewer occupational sitting hours were associated with decreased hazard ratios for colon cancer, particularly distal colon cancer (occupational energy expenditure of ≥12 vs. <8 kJ/minute, hazard ratio (HR) = 0.71, 95% confidence interval (CI): 0.52, 0.97; P for trend = 0.01; occupational sitting hours of <2 vs. 6-8 hours/day, HR = 0.63, 95% CI: 0.48, 0.83; P for trend = 0.001). The median duration of the longest held job for male subcohort members was 29 years. Nonoccupational physical activity was inconsistently associated with colorectal cancer endpoints in men, and it was inversely associated with colon cancer in women, particularly distal colon cancer (>90 vs. ≤30 minutes/day, HR = 0.69, 95% CI: 0.50, 0.96; P for trend = 0.06), and rectal cancer (>90 vs. ≤30 minutes/day, HR = 0.59, 95% CI: 0.39, 0.90; P for trend = 0.02). In conclusion, regular long-term physical activity and fewer sitting hours may protect against colon cancer, particularly distal colon cancer; results for rectal cancer were mixed.

Dietary flavonol, flavone and catechin intake and risk of colorectal cancer in the Netherlands Cohort Study

Dietary flavonoids are hypothesized to be protective against colorectal cancer, yet findings have been inconsistent. We examined the association of dietary flavonol, flavone and catechin intake with colorectal cancer endpoints within the Netherlands Cohort Study (NLCS). In addition, we explored whether body mass index (BMI) may be an effect modifier of this association. The NLCS includes 120,852 men and women who were 55–69 years and completed a self‐administered questionnaire at baseline in 1986. A case‐cohort approach was used for data processing and analysis. After 13.3 years, 1,444 male and 1,041 female colorectal cancer cases were available for estimation of hazard ratios and 95% confidence intervals for quintiles of flavonoid intake. After adjustment for potential confounders, no association of total flavonol and flavone intake and total catechin intake with colorectal cancer endpoints was observed. Analyses stratified for BMI showed significant inverse trends in the association of total catechin intake, (+)‐catechin intake and (–)‐epicatechin intake with rectal cancer in men with a BMI ≥ 25 kg/m2 and in the association of total catechin intake and intake of kaempferol, myricetin and all individual catechins with colorectal cancer, in particular colon cancer, in women with a BMI < 25 kg/m2. In conclusion, our findings generally do not support an association of dietary flavonol, flavone and catechin intake with colorectal cancer endpoints. Dietary catechin intake may be associated with a decreased rectal cancer risk in overweight men. Dietary flavonol and catechin intake may be associated with a decreased colorectal cancer risk in normal weight women.

Body Size and Colorectal Cancer Risk After 16.3 Years of Follow-up: An Analysis From the Netherlands Cohort Study

A large body size may differentially influence risk of colorectal cancer (CRC) by anatomic location. The Netherlands Cohort Study includes 120,852 men and women aged 55-69 years who self-reported weight, height, and trouser/skirt size at baseline (1986), as well as weight at age 20 years. Derived variables included body mass index (BMI; weight (kg)/height (m)(2)), BMI at age 20 years, and BMI change. After 16.3 years of follow-up (1986-2002), 2,316 CRC cases were available for case-cohort analysis. In men, the highest risk estimates were observed for body fat (per 5-unit increase in BMI, hazard ratio (HR) = 1.25, 95% confidence interval (CI): 1.05, 1.46; for highest quintile of trouser size vs. lowest, HR = 1.63, 95% CI: 1.17, 2.29 (P-trend = 0.02)) and appeared more closely associated with distal colon tumors (for BMI (5-unit increase), HR = 1.42, 95% CI: 1.13, 1.79; for highest quintile of trouser size, HR = 2.56, 95% CI: 1.55, 4.24 (P-trend < 0.01)) than with proximal colon or rectal tumors. In women, body fat was not associated with CRC risk unless it was considered simultaneously with physical activity; a large trouser/skirt size and a low level of physical activity increased risk for all subtypes. Height was associated with risk of CRC, especially distal colon tumors (highest quintile vs. lowest: HR = 1.53, 95% CI: 1.03, 2.27; P-trend = 0.05), in women only.

Self-reported clothing size as a proxy measure for body size.

Background: Few studies have considered the potential utility of clothing size as a predictor of diseases associated with body weight. Methods: We used data on weight-stable men and women from a subcohort of the Netherlands Cohort Study to assess the correlation of clothing size with other anthropometric variables. Cox regression using the case-cohort approach was performed to establish whether clothing size can predict cancer risk after 13.3 years of follow-up, and if additionally considering body mass index (BMI) in the model improves the prediction. Results: Trouser and skirt size correlated well with circumference measurements. Skirt size predicted endometrial cancer risk, and this effect was slightly attenuated when BMI was added to the model. Trouser size predicted risk of renal cell carcinoma, regardless of whether BMI was in the model. Conclusions: Clothing size appears to predict cancer risk independently of BMI, suggesting that clothing size is a useful measure to consider in epidemiologic studies when waist circumference is not available.

Pharmacoepigenomics in colorectal cancer: a step forward in predicting prognosis and treatment response

Despite therapeutic innovations and increasing education on lifestyle to prevent colorectal cancer, it is still one of the most common cancer types, and for men the second cause of cancer-related death. Lately, much attention has been given to identify molecular markers involved in colorectal cancer prognosis and treatment with the aim to develop a more accurate classification system based on (epi)genetic alterations and, in addition, find markers that could potentially enhance management of colorectal cancer by predicting treatment response in advance. Although many genetic markers have been claimed to have prognostic or predictive influence, results are often inconclusive and, with some exception, they are not used in standard practice. Epigenetic alterations have received less attention although they are probably even more interesting as they can potentially be reversed through drug treatment. This review describes the current knowledge on the prognostic and predictive value of epigenetic markers in colorectal cancer.

The mTOR Pathway and the Role of Energy Balance Throughout Life in Colorectal Cancer Etiology and Prognosis: Unravelling Mechanisms Through a Multidimensional Molecular Epidemiologic Approach

Timing of exposure to lifestyle factors that influence energy balance may differentially affect colorectal cancer (CRC) risk and prognosis. Caloric restriction in youth and short stature, as markers of early-life exposures, have shown to decrease CRC risk, whereas large body size and low physical activity levels in adulthood are established risk factors for CRC. Regarding prognosis, overweight, sarcopenia, and their co-occurrence (sarcopenic obesity) may negatively influence the health and quality of life of CRC survivors. There is mechanistic support for disruption of the mammalian target of rapamycin (mTOR) pathway as an underlying mechanism possibly driving these associations, because mTOR integrates signals from growth factors, nutrients, mutagens, and hormones to induce cell proliferation, resistance to apoptosis, and autophagy. However, epidemiologic evidence connecting mTOR to energy-balance-related CRC throughout the lifespan is scarce. This perspective proposes how multidimensional molecular epidemiologic studies can shed light on the etiology and prognosis of energy-balance-related CRC.