Case-control study of candidate gene methylation and adenomatous polyp formation

PURPOSE

Colorectal cancer (CRC) is one of the most common and preventable forms of cancer but remains the second leading cause of cancer-related death. Colorectal adenomas are precursor lesions that develop in 70-90 % of CRC cases. Identification of peripheral biomarkers for adenomas would help to enhance screening efforts. This exploratory study examined the methylation status of 20 candidate markers in peripheral blood leukocytes and their association with adenoma formation.

METHODS

Patients recruited from a local endoscopy clinic provided informed consent and completed an interview to ascertain demographic, lifestyle, and adenoma risk factors. Cases were individuals with a histopathologically confirmed adenoma, and controls included patients with a normal colonoscopy or those with histopathological findings not requiring heightened surveillance (normal biopsy, hyperplastic polyp). Methylation-specific polymerase chain reaction was used to characterize candidate gene promoter methylation. Odds ratios (ORs) and 95 % confidence intervals (95% CIs) were calculated using unconditional multivariable logistic regression to test the hypothesis that candidate gene methylation differed between cases and controls, after adjustment for confounders.

RESULTS

Complete data were available for 107 participants; 36 % had adenomas (men 40 %, women 31 %). Hypomethylation of the MINT1 locus (OR 5.3, 95% CI 1.0-28.2) and the PER1 (OR 2.9, 95% CI 1.1-7.7) and PER3 (OR 11.6, 95% CI 1.6-78.5) clock gene promoters was more common among adenoma cases. While specificity was moderate to high for the three markers (71-97 %), sensitivity was relatively low (18-45 %).

CONCLUSION

Follow-up of these epigenetic markers is suggested to further evaluate their utility for adenoma screening or surveillance.

Dietary Inflammatory Index and Risk of Colorectal Adenoma Recurrence: A Pooled Analysis

No studies have evaluated the association between the dietary inflammatory index (DII) and colorectal adenoma recurrence. DII scores were calculated from a baseline food frequency questionnaire. Participants (n = 1727) were 40-80 years of age, enrolled in two Phase III clinical trials, who had ≥1 colorectal adenoma(s) removed within 6 months of study registration, and a follow-up colonoscopy during the trial. Multiple logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs). No statistically significant associations were found between DII and odds of colorectal adenoma recurrence [ORs (95% CIs) = 0.93 (0.73, 1.18) and 0.95 (0.73, 1.22)] for subjects in the second and third DII tertiles, respectively, compared to those in the lowest tertile (P_trend = 0.72). No associations were found for recurrent colorectal adenoma characteristics, including advanced recurrent adenomas, large size, villous histology, or anatomic location. While our study did not support an association between a proinflammatory diet and colorectal adenoma recurrence, future studies are warranted to elucidate the role of a proinflammatory diet on the early stages of colorectal carcinogenesis.

Pancreatic Cancer: Associations of Inflammatory Potential of Diet, Cigarette Smoking, and Long-Standing Diabetes

Background: Pancreatic cancer (PanC) is a rapidly lethal malignancy with poorly understood etiology. Epidemiologic studies show strong associations between PanC and inflammatory conditions or stimuli such as cigarette smoking and diabetes, suggesting that inflammation may play a key role in PanC. Studies of dietary patterns and cancer outcomes also suggest that diet might influence an individual's risk of PanC through modulation of inflammation. We, therefore, examined independent and joint associations between inflammatory potential of diet, cigarette smoking and long-standing type II diabetes (greater than 5 years) in relation to risk of PanC. Methods: Data were from a clinic-based, case-control study of rapidly ascertained patients with incident adenocarcinoma of the exocrine pancreas (n = 819) evaluated at Mayo Clinic and non-cancer control patients (n = 1,769) recruited from Mayo Clinic primary care facilities. Controls were frequency-matched to cases on age, race, and sex. Inflammatory potential of diet was measured using the dietary inflammatory index (DII), calculated from dietary intake assessed via a 144-item food frequency questionnaire and adjusted for energy intake. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for age, sex, race, body mass index, diabetes, smoking, and education. Results: Higher DII scores, reflecting a more pro-inflammatory diet, were associated with increased odds of PanC (OR Quintile5vs1 = 2.80, 95% CI, 2.06–3.79, Ptrend < 0.0001). Increased odds of PanC also were observed among current (OR = 2.55, 95% CI, 1.75–3.72) and former (OR = 1.26, 95% CI, 1.05–1.51) smokers as compared to non- smokers, and among participants with long-standing type II diabetes (OR = 2.96, 95% CI, 1.95–4.51) compared to non-diabetics. Joint associations were observed for the combined effect of having greater than the control median DII score and a) being a current smoker (OR = 4.20, 95% CI, 2.67–6.61),or b) having long-standing type II diabetes (OR = 6.13, 95% CI, 3.47–10.80) as compared to having less than or equal to the control median DII score and being a non-smoker or non-diabetic, respectively. Conclusion: These findings suggest that a pro-inflammatory diet may act synergistically with cigarette smoking and diabetes to increase the risk of PanC beyond the risk of any of these factors alone.

Association Between Post-Cancer Diagnosis Dietary Inflammatory Potential and Survival in WHI Observational Study and Dietary Modification Trial

Background: Inflammation regulates key biologic processes in chronic disease and can be modulated by diet. Our objective was to use the dietary inflammatory index (DII), a novel tool to characterize the inflammatory potential of diet, to examine how post-cancer diagnosis dietary quality is associated with overall survival in the Women's Health Initiative (WHI) Observational Study (OS) and Dietary Modification Trial (DM). Methods: After excluding baseline cancers and energy outliers, the analytical cohort had 4,241 postmenopausal women (19% of total cancer cases), aged 50 to 79 years at baseline, in the WHI OS (n = 1,852) and DM (n = 2,389), who developed invasive cancer during follow-up and completed a food frequency questionnaire after diagnosis. These women were followed from dietary assessment until death from any cause. Energy-adjusted DII scores from food only and from food plus supplement (any reported dietary supplement related to DII parameters) after cancer diagnosis for each subject were calculated by multiplying the inflammatory effect scores determined based on extensive literature review and intake values for each food parameter, and then summing across all the food parameters. Death was ascertained by clinical center follow-up or by searching the National Death Index with central or local adjudication. Cox proportional hazards models were fit to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CI) for all-cause mortality comparing women in higher DII quartiles with those in the first quartile. Results: After a median 11.2 years of follow-up, 1,470 deaths occurred. After adjustment for key covariates, women who consumed a more pro-inflammatory diet (in higher quartiles of DII score from food only) after a cancer diagnosis had a significantly higher risk of death from any cause compared to women consuming a more anti- inflammatory diet (HR Q4:Q1 = 1.18; 95% CI, 1.01–1.38; P trend = 0.015). In analyses using DII score from both diet and supplements, a pro-inflammatory DII score was associated with even higher risk of all-cause mortality (HRQ4:Q1 = 1.63; 95% CI, 1.40–1.91; P trend < 0.0001). Conclusions: Consuming a more pro-inflammatory diet after cancer diagnosis was associated with increased risk of death from any cause.

Abstract P6-09-08: Exposure to multiple sources of polycyclic aromatic hydrocarbon and breast cancer incidence

Background. Previous epidemiologic studies, including our own, have consistently linked long-term exposure to single-source polycyclic aromatic hydrocarbons (PAHs) to increased breast cancer incidence. It is unclear whether single sources, specific groups, or all PAH sources should be targeted for breast cancer risk reduction. This study considers the impact on breast cancer incidence from multiple PAH exposure sources in a single model, which better reflects exposure to these complex mixtures.

Methods. In a population-based case-control study conducted on Long Island, New York (N=1,508 breast cancer cases/1,556 controls), a Bayesian hierarchical regression approach was used to estimate adjusted posterior means and credible intervals (CrI) for the adjusted odds ratios (ORs) for PAH exposure sources, considered singly and as groups: active smoking; residential environmental tobacco smoke (ETS); indoor and outdoor air pollution; and grilled/smoked meat intake.

Results. Most women were exposed to PAHs from multiple sources. In a hierarchical model, breast cancer incidence was positively associated with ETS from a spouse (OR=1.20, 95%CrI=1.03, 1.42) and residential synthetic firelog burning (OR=1.30, 95%CrI=1.06, 1.60). Additionally, PAH exposure groups, including ingestion (OR=1.45, 95%CrI=1.16, 1.79), indoor stove/fireplace use (OR=1.30, 95%CrI=1.02, 1.62), and total indoor sources (active smoking, ETS from spouse, grilled/smoked meat intake, stove/fireplace use, OR=1.46, 95%CrI=1.03, 2.05), were associated with increased breast cancer incidence.

Conclusions. Groups of PAH sources, especially those for ingestion and indoor sources, were associated with a 30-50% increase in breast cancer incidence. PAH exposure is ubiquitous and a potentially modifiable breast cancer risk factor.

Citation Format: White AJ, Bradshaw PT, Herring AH, Teitelbaum SL, Beyea J, Stellman SD, Steck SE, Mordukhovich I, Eng SM, Engel LS, Conway K, Hatch M, Neugut AI, Santella RM, Gammon MD. Exposure to multiple sources of polycyclic aromatic hydrocarbon and breast cancer incidence. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-09-08.

Abstract P1-08-04: Sources of polycyclic aromatic hydrocarbons associated with gene-specific promoter methylation in women with breast cancer

Tobacco smoke, diet, and indoor and outdoor air pollution, all major sources of polycyclic aromatic hydrocarbons (PAHs), have been associated with breast cancer incidence. Aberrant methylation may be an early event in carcinogenesis, but whether PAHs influence the epigenome is unclear. Few studies have evaluated whether PAHs are associated with methylation, particularly in breast tumors where methylation changes are particularly relevant. In a population-based case-control study, we measured promoter methylation of 13 breast cancer-related genes in breast tumor tissue (n=765-851 cases) and global methylation in peripheral blood (1,055 cases/1,101 controls). PAH sources (current active smoking, residential environmental tobacco smoke (ETS), vehicular traffic, synthetic log burning, and grilled/smoked meat intake) were evaluated separately. Logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). When comparing methylated versus unmethylated genes, synthetic log use was associated with increased ORs for CDH1 (OR=2.28, 95%CI=1.07-4.83), HIN1 (OR=2.11, 95%CI=1.32-3.38) and RARβ methylation (OR=1.82, 95%CI=1.18-2.83) and decreased ORs for BRCA1 methylation (OR=0.44, 95%CI=0.30-0.65). Residential ETS was associated with decreased ORs for ESR1 (OR=0.74, 95%CI=0.56-0.99) and CCND2 methylation (OR=0.65, 95%CI=0.44-0.96). Current smoking and vehicular traffic were associated with decreased ORs for DAPK (OR=0.53, 95%CI=0.28-0.99) and increased ORs for TWIST1 methylation (OR=2.79, 95%CI=1.24-6.30), respectively. In controls, synthetic log use was inversely associated with LINE-1 methylation (OR=0.60, 95%CI=0.42-0.87). PAH sources were associated with hypo- and hypermethylation at multiple promoter regions in breast tumors and LINE-1 hypomethylation in blood of controls. Methylation may be a potential biologic mechanism for the association between PAHs and breast cancer incidence.

Citation Format: White AJ, Chen J, McCullough LE, Xu X, Cho YH, Conway K, Beyea J, Stellman SD, Steck SE, Mordukhovich I, Eng SM, Terry MB, Engel LS, Hatch M, Neugut AI, Hibshoosh H, Santella RM, Gammon MD. Sources of polycyclic aromatic hydrocarbons associated with gene-specific promoter methylation in women with breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-08-04.

Allergic sensitization and filaggrin variants predispose to the comorbidity of eczema, asthma, and rhinitis: results from the Isle of Wight birth cohort

BACKGROUND

Allergic sensitization and filaggrin gene (FLG) variants are important risk factors for allergic disorders; however, knowledge on their individual and interactive effects on the coexistence of eczema, asthma, and rhinitis is lacking.

OBJECTIVE

This study aimed at investigating the single and combined effects of allergic sensitization and FLG variants on the development of single and multiple allergic disorders.

METHODS

The Isle of Wight birth cohort (n = 1456) has been examined at 1, 2, 4, 10, and 18 years of age. Repeated measurements of eczema, asthma, rhinitis, and skin prick tests were available for all follow-ups. FLG variants were genotyped in 1150 participants. Associations of allergic sensitization and FLG variants with single and multiple allergic disorders were tested in log-binomial regression analysis.

RESULTS

The prevalence of eczema-, asthma-, and rhinitis-only ranged from 5.6% to 8.5%, 4.9% to 10.2%, and 2.5% to 20.4%, respectively, during the first 18 years of life. The coexistence of allergic disorders is common, with approximately 2% of the population reporting the comorbidity of 'eczema, asthma, and rhinitis' during the study period. In repeated measurement analyses, allergic sensitization and FLG variants, when analysed separately, were associated with having single and multiple allergic disorders. Of particular significance, their combined effect increased the risk of 'eczema and asthma' (RR = 13.67, 95% CI: 7.35-25.42), 'asthma and rhinitis' (RR = 7.46, 95% CI: 5.07-10.98), and 'eczema, asthma, and rhinitis' (RR = 23.44, 95% CI: 12.27-44.78).

CONCLUSIONS AND CLINICAL RELEVANCE

The coexistence of allergic disorders is frequent, and allergic sensitization and FLG variants jointly increased risk of allergic comorbidities, which may represent more severe and complex clinical phenotypes. The interactive effect and the elevated proportion of allergic comorbidities associated with allergic sensitization and FLG variants emphasize their joint importance in the pathogenesis of allergic disorders.

Dietary intake of flavonoids and oesophageal and gastric cancer: incidence and survival in the United States of America (USA)

BACKGROUND

Flavonoids, polyphenolic compounds concentrated in fruits and vegetables, have experimentally demonstrated chemopreventive effects against oesophageal and gastric cancer. Few epidemiologic studies have examined flavonoid intake and incidence of these cancers, and none have considered survival.

METHODS

In this USA multicentre population-based study, case participants (diagnosed during 1993-1995 with oesophageal adenocarcinoma (OEA, n=274), gastric cardia adenocarcinoma (GCA, n=248), oesophageal squamous cell carcinoma (OES, n=191), and other gastric adenocarcinoma (OGA, n=341)) and frequency-matched controls (n=662) were interviewed. Food frequency questionnaire responses were linked with USDA Flavonoid Databases and available literature for six flavonoid classes and lignans. Case participants were followed until 2000 for vital status. Multivariable-adjusted odds ratios (ORs) and hazard ratios (HRs) (95% confidence intervals (CIs)) were estimated, comparing highest with lowest intake quartiles, using polytomous logistic and proportional hazards regressions, respectively.

RESULTS

Little or no consistent association was found for total flavonoid intake (main population sources: black tea, orange/grapefruit juice, and wine) and incidence or survival for any tumour type. Intake of anthocyanidins, common in wine and fruit juice, was associated with a 57% reduction in the risk of incident OEA (OR=0.43, 95% CI=0.29-0.66) and OES (OR=0.43, 95% CI=0.26-0.70). The ORs for isoflavones, for which coffee was the main source, were increased for all tumours, except OES. Anthocyanidins were associated with decreased risk of mortality for GCA (HR=0.63, 95% CI=0.42-0.95) and modestly for OEA (HR=0.87, 95% CI=0.60-1.26), but CIs were wide.

CONCLUSIONS

Our findings, if confirmed, suggest that increased dietary anthocyanidin intake may reduce incidence and improve survival for these cancers.

Components of variation in serum carotenoid concentrations: the Polyp Prevention Trial

OBJECTIVES

The intra- and interindividual variations and season and center effects were estimated from a series of serum carotenoid concentrations in the Polyp Prevention Trial (PPT) participants.

SUBJECTS/METHODS

Fasting blood was collected annually for 4 years in all 1905 participants, and a subcohort of 901 participants were selected within each (of eight) center(s), by gender and dietary arm of the study, for measurement of five major carotenoid peaks. Using variance of component methods, the variation in serum carotenoid concentrations about the underlying mean was partitioned into explanatory components attributed to various sources.

RESULTS

The contributions of the inter- and intraindividual variances to the overall variation in carotenoid concentrations were in the range of 61-70 and 20-35%, respectively, whereas center and center-by-season effects provided 2.6-9.5 and 0.2-1.4%, respectively. The highest percent (35%) of intraindividual variation was exhibited by lycopene, and the highest percent (70% apiece) of interindividual variation was exhibited by lutein/zeaxanthin and beta-carotene. Serum lycopene had the highest ratio of intra- to interindividual variation of 0.57, whereas lutein had the lowest ratio of 0.29. We estimate that the ratio of intra- to interindividual variance around the mean carotenoid concentration can be reduced greatly by collecting 3-4 compared to 1 blood measurement in large-scale trials like the PPT.

CONCLUSION

In the largest study of components of variation in individuals at high risk for colorectal cancer, the largest contributors to variation in serum carotenoid concentrations were intra- and interindividual effects followed by center and center-by-season effects.

Interactions among GSTM1, GSTT1 and GSTP1 polymorphisms, cruciferous vegetable intake and breast cancer risk

Isothiocyanates are anticarcinogenic phytochemicals found in cruciferous vegetables that both induce and are substrates for the gluthatione S-transferases (GSTs). The GSTs are phase II metabolizing enzymes involved in metabolism of various bioactive compounds. Functional polymorphisms in GST genes have been identified and may interact with cruciferous vegetable intake to affect cancer risk. We examined this hypothesis using data from the Long Island Breast Cancer Study Project, a population-based case-control study conducted in Long Island, NY, from 1996 to 1997. Cruciferous vegetable intake in the previous year was assessed via modified Block food frequency questionnaire. DNA was extracted from blood samples (n = 1052 cases and n = 1098 controls) and genotyped for GSTM1 deletion, GSTT1 deletion and GSTP1 Ile105Val using multiplex polymerase chain reaction and Taqman assays. Unconditional logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CI). We found an 86% increase in the OR for breast cancer among carriers of the GSTM1 null, GSTT1 null and GSTP 105Ile/Ile genotypes (OR = 1.86, 95% CI = 1.12, 3.08) and a 36% decrease in the OR among carriers of GSTM1 present, GSTT1 null and GSTP1 105Ile/Val + Val/Val genotypes (OR = 0.64, 95% CI = 0.42, 0.97) compared with GSTM1 present, GSTT1 present and GSTP1 105Ile/Ile carriers. We found no joint effects among GST polymorphisms and cruciferous vegetable intake and breast cancer risk. In conclusion, we found associations between specific combinations of three GST gene polymorphisms and breast cancer risk but these did not modify the association between cruciferous vegetable intake and breast cancer. Additional studies are needed to confirm the associations observed.

Multiple effects of codon usage optimization on expression and immunogenicity of DNA candidate vaccines encoding the human immunodeficiency virus type 1 Gag protein

We have analyzed the influence of codon usage modifications on the expression levels and immunogenicity of DNA vaccines, encoding the human immunodeficiency virus type 1 (HIV-1) group-specific antigen (Gag). In the presence of Rev, an expression vector containing the wild-type (wt) gag gene flanked by essential cis-acting sites such as the 5'-untranslated region and 3'-Rev response element supported substantial Gag protein expression and secretion in human H1299 and monkey COS-7 cells. However, only weak Gag production was observed from the murine muscle cell line C2C12. In contrast, optimization of the Gag coding sequence to that of highly expressed mammalian genes (syngag) resulted in an obvious increase in the G+C content and a Rev-independent expression and secretion of Gag in all tested mammalian cell lines, including murine C2C12 muscle cells. Mice immunized intramuscularly with the syngag plasmid showed Th1-driven humoral and cellular responses that were substantially higher than those obtained after injection of the Rev-dependent wild-type (wt) gag vector system. In contrast, intradermal immunization of both wt gag and syngag vector systems with the particle gun induced a Th2-biased antibody response and no cytotoxic T lymphocytes. Deletion analysis demonstrated that the CpG motifs generated within syngag by codon optimization do not contribute significantly to the high immunogenicity of the syngag plasmid. Moreover, low doses of coadministered stimulatory phosphorothioate oligodeoxynucleotides (ODNs) had only a weak effect on antibody production, whereas at higher doses immunostimulatory and nonstimulatory ODNs showed a dose-dependent suppression of humoral responses. These results suggest that increased Gag expression, rather than modulation of CpG-driven vector immunity, is responsible for the enhanced immunogenicity of the syngag DNA vaccine.

Lycopene and cardiovascular disease

Considerable evidence suggests that lycopene, a carotenoid without provitamin A activity found in high concentrations in a small set of plant foods, has significant antioxidant potential in vitro and may play a role in preventing prostate cancer and cardiovascular disease in humans. Tomato products, including ketchup, tomato juice, and pizza sauce, are the richest sources of lycopene in the US diet, accounting for >80% of the total lycopene intake of Americans. Unlike other carotenoids, lycopene is not consistently lower among smokers than among nonsmokers, suggesting that any possible preventive activity is not as an antioxidant. Instead, lycopene may have a cholesterol synthesis-inhibiting effect and may enhance LDL degradation. Available evidence suggests that intimal wall thickness and risk of myocardial infarction are reduced in persons with higher adipose tissue concentrations of lycopene. The question of whether lycopene helps to prevent cardiovascular disease can only be answered by a trial specifically evaluating its effectiveness in this area.

Lycopene and myocardial infarction risk in the EURAMIC Study

A multicenter case-control study was conducted to evaluate the relations between antioxidant status assessed by biomarkers and acute myocardial infarction. Incidence cases and frequency matched controls were recruited from 10 European countries to maximize the variance in exposure within the study. Adipose tissue needle aspiration biopsies were taken shortly after the infarction and analyzed for levels of carotenoids and tocopherols. An examination of colinearity including all covariates and the three carotenoids, alpha-carotene, beta-carotene, and lycopene, showed that the variables were sufficiently independent to model simultaneously. When examined singularly, each of the carotenoids appeared to be protective. Upon simultaneous analyses of the carotenoids, however, using conditional logistic regression models that controlled for age, body mass index, socioeconomic status, smoking, hypertension, and maternal and paternal history of disease, lycopene remained independently protective, with an odds ratio of 0.52 for the contrast of the 10th and 90th percentiles (95% confidence interval 0.33-0.82, p = 0.005). The associations for alpha- and beta-carotene were largely eliminated. We conclude that lycopene, or some substance highly correlated which is in a common food source, may contribute to the protective effect of vegetable consumption on myocardial infarction risk.

Tea and cancer prevention: an evaluation of the epidemiologic literature

Animal and in vitro studies provide evidence of an anticarcinogenic potential of active ingredients in teas. This review encompasses epidemiologic studies of stomach, colon, and lung cancer as well as the evidence of a relationship between tea drinking and cancer at large in humans. Cohort studies do not suggest a protective role for tea drinking in the total risk of cancer. Site-specific studies reveal a more complex picture. The epidemiologic studies on tea drinking and stomach cancer do not justify claims of a cancer-protective effect. A protective effect of green tea on the development of colon cancer is suggested. The evidence regarding black tea is less clear, with some indication of a risk of colon or rectal cancer associated with regular use of black tea. The studies on tea and lung cancer also suggest an increased risk with increased tea consumption. The range and crude categorization of tea consumption, choice of control groups, and inadequate control for confounding might have obscured possible relationships. From the limited studies that suggest a favorable effect from tea, it is likely that benefits are restricted to high intakes in high-risk populations.