This study examined the role of dopaminergic genes in prospective smoking cessation and response to bupropion treatment in a placebo-controlled clinical trial. Smokers of European ancestry (N=418) provided blood samples for genetic analysis and received either bupropion or placebo (10 weeks) plus counseling. Assessments included the dopamine D2 receptor (DRD2) genotype, dopamine transporter (SLC6A3) genotype, demographic factors, and nicotine dependence. Smoking status was verified at the end of treatment (EOT) and at 6-month follow-up. The results provided evidence for a significant DRD2 * SLC6A3 interaction effect on prolonged smoking abstinence and time to relapse at EOT, independent of treatment condition. Such effects were no longer significant at 6-month follow-up, however. These results provide the first evidence from a prospective clinical trial that genes that alter dopamine function may influence smoking cessation and relapse during the treatment phase.

Despite the efficacy of bupropion for smoking cessation, smokers exhibit variability in treatment outcome. The CYP2B6 gene has been implicated in bupropion kinetics and nicotine metabolism, and is a plausible candidate for pharmacogenetic studies of treatment response. We investigated whether a functional genetic polymorphism in the CYP2B6 gene predicts smoking outcomes in a placebo-controlled randomized trial. Four hundred and twenty-six smokers of European Caucasian ancestry provided blood samples and received bupropion (300 mg/day for 10 weeks) or placebo, plus counseling. Smoking status, abstinence symptoms and side-effects were recorded weekly, and smoking status was verified at the end of treatment and at 6-month follow-up. Smokers with a decreased activity variant of CYP2B6 reported greater increases in cravings for cigarettes following the target quit date and had higher relapse rates. These effects were modified by a significant gender x genotype x treatment interaction, suggesting that bupropion attenuated the effects of genotype among female smokers. We conclude that smokers with the CYP2B6 variant may be more vulnerable to abstinence symptoms and relapse. Bupropion may attenuate these effects, especially among females. Additional trials are warranted to confirm these results, as are studies to explore the neurobiological mechanisms. Such research could ultimately enable practitioners to select the optimal type and dose of medication for individual smokers.

Aberrant DNA hypermethylation of gene promoter regions has been increasingly recognized as a common molecular alteration in carcinogenesis. We evaluated the association between major clinicopathological features and hypermethylation of genes in tumors among 803 incidence breast cancer cases from a large population-based case-control study conducted in Western New York State. DNA samples were isolated from archive paraffin embedded tumor tissue and were analyzed for hypermethylation status of the E-cadherin, p16, and RAR-β 2 genes using real time methylation-specific polymerase chain reaction. The frequencies of hypermethylation were 20.0% for E-cadherin, 25.9% for p16, and 27.5% for RAR-β 2 genes. For postmenopausal women, hypermethylation of E-cadherin tended to be more likely in progesterone receptor (PR) negative than in PR-positive tumors (odds ratio (OR), 1.41; 95% confidence interval (CI), 0.91-2.18). Hypermethylation of p16 tended to be more frequent among estrogen receptor (ER) negative cases than ER-positive cases (OR, 1.51; 95% CI, 1.01-2.32). Hypermethylation of RAR-β 2 gene was inversely associated with histological and nuclear grade of breast cancer.

Base excision repair (BER) and nucleotide excision repair (NER) pathways repair damaged DNA, and polymorphisms in these genes might affect breast cancer susceptibility. We evaluated associations between seven single-nucleotide polymorphisms in four DNA repair genes (ERCC4 rs1799801, XPC rs2227998, rs2228001, rs2228000, OGG1 rs1052133 and XRCC1 rs25487 and rs25486) and breast cancer risk, examining modification by smoking and alcohol consumption, using data from the Western New York Exposures and Breast Cancer Study. Women aged 35-79 years with incident breast cancer (n = 1170) and age- and race-matched controls (n = 2115) were enrolled. Genotyping was performed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Unconditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CIs). No significant associations were observed in premenopausal women. Among postmenopausal women, rs25487 and rs25486 (OR = 1.24; 95% CI 1.01-1.51 and OR = 1.23; 95% CI 1.01-1.49, respectively, for combined heterozygous and homozygous variant compared with reference) were associated with increased risk of breast cancer. Postmenopausal women carrying the variant allele of the synonymous XPC polymorphism (rs2227998) were also at borderline significantly increased risk (OR = 1.24; 95% CI 1.01-1.52, heterozygous variant compared with reference; OR = 1.22; 95% CI 1.01-1.48, for combined heterozygous and homozygous variant compared with reference). There was no evidence of genotype-smoking and genotype-alcohol consumption interactions for pre- and postmenopausal women. These results indicate that some of the variants in BER and NER genes may influence risk of postmenopausal breast cancer.

Purpose To determine the hypermethylation status of the promoter regions of tumor suppressor genes in normal breast tissues and identify the determinants of these epigenetic changes. Experimental design Questionnaires and breast tissues were collected from healthy women without a history of cancer and undergoing reduction mammoplasty (N=141). Methylation for p16INK4, BRCA1, ERα and RAR-β promoter regions from normal breast tissues were determined by methylation specific PCR. Associations were examined with chi-square and Fisher’s exact test as well as logistic regression. All statistical tests were two-sided. Results p16INK4, BRCA1, ERα and RAR-β hypermethylation were identified in 31%, 17% 9% and 0% of the women, respectively. Women with BRCA1 hypermethylation had an eight-fold increase in the risk of ERα hypermethylation (p=0.007). p16INK4 hypermethylation was present in 28% of African-Americans, but 65% in European-Americans (p=0.02). There was an increased likelihood of p16INK4 or BRCA1 hypermethylation for women with family history of cancer (OR 2.3; 95%CI: 1.05–4.85 and OR 5.0; 95%CI: 1.55–15.81, respectively). ERα hypermethylation was associated with family history of breast cancer (OR 6.6; 95%CI: 1.58–27.71). After stratification by race, p16INK4 in European-Americans and BRCA1 hypermethylation in African-Americans were associated with family history of cancer (OR 3.8; 95%CI: 1.21–12.03 and OR 6.5; 95%CI: 1.33–31.32, respectively). Conclusions Gene promoter hypermethylation was commonly found in healthy breast tissues from women without cancer, indicating that these events are frequent and early lesions. Race and family history of cancer increase the likelihood of these early events.

Aberrant promoter methylation is recognized as an important feature of breast carcinogenesis. We hypothesized that genetic variation of genes for methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MTR), two critical enzymes in one-carbon metabolism, may alter DNA methylation levels, and thus influence DNA methylation in breast cancer. We evaluated case-control association of MTHFR C677T, A1298C, and MTR A2756G polymorphisms for cases strata defined by promoter methylation status for each of three genes, E- cadherin, p16, and RAR-β2 in breast cancer; in addition, we evaluated case-case comparisons of likelihood of promoter methylation in relation to genotypes using a population-based case-control study conducted in Western New York State. Methylation was evaluated with real time methylation-specific PCRs for 803 paraffin embedded breast tumor tissues from women with primary, incident breast cancer. We applied unordered polytomous regression and unconditional logistic regression to derive adjusted odds ratios (OR) and 95% confidence intervals (CI). We did not find any association of MTHFR and MTR polymorphisms with breast cancer risk stratified by methylation status nor between polymorphisms and likelihood of promoter methylation of any of the genes. There was no evidence of difference within strata defined by menopausal status, ER status, folate intake and lifetime alcohol consumption. Overall, we found no evidence that these common polymorphisms of the MTHFR and MTR genes are associated with promoter methylation of E- cadherin, p16, and RAR-β2 genes in breast cancer.

Background: The mechanism of the observed association between body mass, particularly centralized body fat, and postmenopausal breast cancer risk is not well understood. Objective: We hypothesized that body mass may affect DNA methylation through increased estrogen and chronic inflammation. The association between body mass and promoter methylation in breast tumors was investigated in a population-based, case-control study. Design: The promoter methylation of E-cadherin, p16, and RAR-b 2 genes was assessed in breast tumor blocks from 803 pre-and postmenopausal cases by using real-time methylation-specific polymerase chain reaction. Unconditional logistic regression was used to derive the adjusted OR and 95% CI for case-case comparisons of tumors with and without promoter methylation of the genes. Results: The frequency of promoter methylation was 20% for E-cadherin, 25.9% for p16, and 27.5% for RAR-b 2 . There was no difference in the prevalence of the DNA methylation of individual genes by BMI, waist-to-hip ratio (WHR), or lifetime weight change between the age of 20 y and the present. However, in a case-case comparison of postmenopausal breast cancer, a greater WHR was associated with an increased likelihood of 1 of the 3 genes being methylated (OR: 1.85; 95% CI: 1.10, 3.11; P-trend , 0.02). Conclusions: We showed that WHR was associated with DNA promoter methylation of 1 of 3 genes in postmenopausal breast tumors. It may be that the association of body fat composition and postmenopausal breast cancer is related to altered DNA methylation. However, future studies in other populations and with an examination of the methylation of more genes are needed.Am J Clin Nutr 2011;94:831-8.

The mechanism for the observed association of alcohol consumption breast cancer risk is not known; understanding that mechanism could improve understanding of breast carcinogenesis and optimize prevention strategies. Alcohol may impact breast malignancies or tumor progression by altering DNA methylation. We examined promoter methylation of three genes, the E- cadherin, p16, and RAR-β2 genes in archived breast tumor tissues from participants in a population-based case-control study. Real time methylation-specific PCR was performed on 803 paraffin-embedded samples; and lifetime alcohol consumption was queried. Unordered polytomous and unconditional logistic regression were used to derive adjusted odds ratios (OR) and 95% confidence intervals (CI). RAR-β2 methylation was not associated with drinking. Among premenopausal women, alcohol consumption was also not associated with promoter methylation for E- cadherin and p16 genes. In case-case comparisons of postmenopausal breast cancer, compared to lifetime never drinkers, promoter methylation likelihood was increased for higher alcohol intake for E - cadherin (OR = 2.39, 95% CI, 1.15–4.96), in particular for those with ER-negative tumors (OR = 4.13, 95% CI, 1.16–14.72), and decreased for p16 (OR = 0.52, 95% CI, 0.29-0.92). There were indications that the association with p16 was stronger for drinking at younger ages. Methylation was also associated with drinking intensity independent of total consumption for both genes. We found alcohol consumption was associated with DNA methylation in postmenopausal breast tumors, suggesting that the association of alcohol and breast cancer may be related, at least in part, to altered methylation, and may differ by drinking pattern.