Alcohol metabolism, alcohol intake, and breast cancer risk: a sister-set analysis using the Breast Cancer Family Registry

Systems biology comprehensive analysis on breast cancer for identification of key gene modules and genes associated with TNM-based clinical stages

Breast cancer (BC), as one of the leading causes of death among women, comprises several subtypes with controversial and poor prognosis. Considering the TNM (tumor, lymph node, metastasis) based classification for staging of breast cancer, it is essential to diagnose the disease at early stages. The present study aims to take advantage of the systems biology approach on genome wide gene expression profiling datasets to identify the potential biomarkers involved at stage I, stage II, stage III, and stage IV as well as in the integrated group. Three HER2-negative breast cancer microarray datasets were retrieved from the GEO database, including normal, stage I, stage II, stage III, and stage IV samples. Additionally, one dataset was also extracted to test the developed predictive models trained on the three datasets. The analysis of gene expression profiles to identify differentially expressed genes (DEGs) was performed after preprocessing and normalization of data. Then, statistically significant prioritized DEGs were used to construct protein-protein interaction networks for the stages for module analysis and biomarker identification. Furthermore, the prioritized DEGs were used to determine the involved GO enrichment and KEGG signaling pathways at various stages of the breast cancer. The recurrence survival rate analysis of the identified gene biomarkers was conducted based on Kaplan-Meier methodology. Furthermore, the identified genes were validated not only by using several classification models but also through screening the experimental literature reports on the target genes. Fourteen (21 genes), nine (17 genes), eight (10 genes), four (7 genes), and six (8 genes) gene modules (total of 53 unique genes out of 63 genes with involving those with the same connectivity degree) were identified for stage I, stage II, stage III, stage IV, and the integrated group. Moreover, SMC4, FN1, FOS, JUN, and KIF11 and RACGAP1 genes with the highest connectivity degrees were in module 1 for abovementioned stages, respectively. The biological processes, cellular components, and molecular functions were demonstrated for outcomes of GO analysis and KEGG pathway assessment. Additionally, the Kaplan-Meier analysis revealed that 33 genes were found to be significant while considering the recurrence-free survival rate as an alternative to overall survival rate. Furthermore, the machine learning calcification models show good performance on the determined biomarkers. Moreover, the literature reports have confirmed all of the identified gene biomarkers for breast cancer. According to the literature evidence, the identified hub genes are highly correlated with HER2-negative breast cancer. The 53-mRNA signature might be a potential gene set for TNM based stages as well as possible therapeutics with potentially good performance in predicting and managing recurrence-free survival rates at stages I, II, III, and IV as well as in the integrated group. Moreover, the identified genes for the TNM-based stages can also be used as mRNA profile signatures to determine the current stage of the breast cancer.

Alcohol drinking, ADH1B and ADH1C genotypes and the risk of postmenopausal breast cancer by hormone receptor status: the Netherlands Cohort Study on diet and cancer

Alcohol consumption has consistently been shown to increase breast cancer (BC) risk. This association may be modified by single nucleotide polymorphisms (SNPs) in alcohol dehydrogenase (ADH) isoenzymes ADH1B and ADH1C. The Netherlands Cohort Study comprises 62 573 women, aged 55-69 years at baseline (1986). Follow-up for postmenopausal BC for 20.3 years was available. Genotyping of six tag SNPs in ADH1B and ADH1C was performed on DNA from toenails. A case-cohort approach was used for analysis (complete data available for nsubcohort = 1301; ncases = 1630). Cox regression models for postmenopausal BC were applied to determine marginal effects of alcohol intake and SNPs using a dominant genetic model, as well as multiplicative interaction of the two. Results were also obtained for subtypes by estrogen receptor (ER) and progesterone receptor (PR) status. Multiple testing was adjusted for by applying the false discovery rate (FDR). Alcohol intake (categorical) increased the risk of postmenopausal BC (Ptrend = 0.031). Trends for ER and PR subgroups followed a similar pattern. Continuous modeling of alcohol resulted in a hazard rate ratio (HR) for overall postmenopausal BC of 1.09 (95% confidence interval: 1.01-1.19) per 10 g/day of alcohol. SNPs were not associated with BC risk. No effect modification of the alcohol-BC association by SNP genotype was seen after FDR correction in overall BC and ER/PR subgroups. In conclusion, alcohol consumption was shown to increase the risk of postmenopausal BC. This association was not significantly modified by common SNPs in ADH1B and ADH1C, neither in overall BC nor in hormone receptor-defined subtypes.

Alcohol intake and breast cancer in the European prospective investigation into cancer and nutrition

Alcohol intake has been associated to breast cancer in pre and postmenopausal women; however results are inconclusive regarding tumor hormonal receptor status, and potential modifying factors like age at start drinking. Therefore, we investigated the relation between alcohol intake and the risk of breast cancer using prospective observational data from the European Prospective Investigation into Cancer and Nutrition (EPIC). Up to 334,850 women, aged 35-70 years at baseline, were recruited in ten European countries and followed up an average of 11 years. Alcohol intake at baseline and average lifetime alcohol intake were calculated from country-specific dietary and lifestyle questionnaires. The study outcomes were the Hazard ratios (HR) of developing breast cancer according to hormonal receptor status. During 3,670,439 person-years, 11,576 incident breast cancer cases were diagnosed. Alcohol intake was significantly related to breast cancer risk, for each 10 g/day increase in alcohol intake the HR increased by 4.2% (95% CI: 2.7-5.8%). Taking 0 to 5 g/day as reference, alcohol intake of >5 to 15 g/day was related to a 5.9% increase in breast cancer risk (95% CI: 1-11%). Significant increasing trends were observed between alcohol intake and ER+/PR+, ER-/PR-, HER2- and ER-/PR-HER2- tumors. Breast cancer risk was stronger among women who started drinking prior to first full-time pregnancy. Overall, our results confirm the association between alcohol intake and both hormone receptor positive and hormone receptor negative breast tumors, suggesting that timing of exposure to alcohol drinking may affect the risk. Therefore, women should be advised to control their alcohol consumption.

Female breast cancer and alcohol consumption: a review of the literature

CONTEXT

Consumption of alcoholic beverages is one of the single most important known and modifiable risk factor for human cancer. Among women, breast cancer is the most common cancer worldwide and the leading cause of cancer-related mortality. Consumption of alcoholic beverages is causally associated with female breast cancer and the association shows a linear dose-response relationship. The role of heavy drinking has been long recognized and even a moderate intake is associated with an increased risk for breast cancer. The present review is an update of the current evidence on the association between alcohol consumption and breast cancer risk. The aim is to gain further insight into this association and to improve our current understanding of the effects of the major modifying factors.

EVIDENCE ACQUISITION

Epidemiologic and experimental studies published since the most recent International Agency for Research on Cancer (IARC) Monograph on alcoholic beverages were identified in PubMed using a combination of keywords such as alcohol, breast cancer, polymorphisms, menopausal status.

EVIDENCE SYNTHESIS

Cumulative lifetime consumption, drinking frequency, drinking patterns and timing of exposure each modulate the association between alcohol consumption and breast cancer. Hormonal status, genetic polymorphisms, and nutritional factors may interact with ethanol metabolism and further influence breast cancer risk.

CONCLUSIONS

Better standardization among experimental and epidemiologic designs in assessing alcohol intake and timing of exposure may improve our understanding of the heterogeneity observed across studies, possibly allowing the quantification of the effects of occasional heavy drinking and the identification of a window of higher susceptibility to breast cancer development.

Oral contraceptive and reproductive risk factors for ovarian cancer within sisters in the breast cancer family registry

BACKGROUND

Oral contraceptive use has been consistently associated with a reduced risk of ovarian cancer in unrelated, average risk women; however little data exist on whether this benefit extends to higher risk women from cancer families. To examine this, we conducted family-based analyses using the Breast Cancer Family Registry.

METHODS

We used generalised estimating equations to obtain the population average effect across all families (n=389 cases, n=5643 controls) and conditional logistic regression to examine within-family differences in a subset with at least two sisters discordant on ovarian cancer status (n=109 cases, n=149 unaffected sister controls).

RESULTS

In the multivariable generalised estimating equation model there was a reduced risk of ovarian cancer for ever use of oral contraceptives compared with never use (OR=0.58, 95% CI: 0.37, 0.91), and in the conditional logistic model there was a similar inverse association; however, it was not statistically significant (OR=0.52, 95% CI: 0.23, 1.17). We examined this association by BRCA1/2 status and observed a statistically significant reduced risk in the non-carriers only.

CONCLUSION

We observed a decreased risk of ovarian cancer with oral contraceptive use supporting that this association observed in unrelated women extends to related women at higher risk.

Alcohol Intake and Breast Cancer Risk: Weighing the Overall Evidence

Moderate alcohol consumption has been linked to an approximate 30-50% increased risk in breast cancer. Case-control and cohort studies have consistently observed this modest increase. We highlight recent evidence from molecular epidemiologic studies and studies of intermediate markers like mammographic density that provide additional evidence that this association is real and not solely explained by factors/correlates of the exposure and outcome present in non-randomized studies. We also review evidence from studies of higher risk women including BRCA1 and BRCA2 mutation carriers. Given the incidence of heart disease is higher than breast cancer and modest alcohol consumption is associated with reduced risk of heart disease, we examine the latest evidence to evaluate if alcohol reduction should be targeted to women at high risk for breast cancer. We also review the most recent evidence on the effect of alcohol use on tumor recurrence and survival for those diagnosed with breast cancer.

Total energy intake and breast cancer risk in sisters: the Breast Cancer Family Registry

Energy restriction inhibits mammary tumor development in animal models. Epidemiologic studies in humans generally do not support an association between dietary energy intake and breast cancer risk, although some studies suggest a more complex interplay between measures of energy intake, physical activity, and body size. We examined the association between total energy intake jointly with physical activity and body mass index (BMI) and the risk of breast cancer among 1,775 women diagnosed with breast cancer between 1995 and 2006 and 2,529 of their unaffected sisters, enrolled in the Breast Cancer Family Registry. We collected dietary data using the Hawaii-Los Angeles Multiethnic Cohort food frequency questionnaire. Using conditional logistic regression to estimate the odds ratios (OR) and 95 % confidence intervals (CI) associated with total energy intake, we observed an overall 60-70 % increased risk of breast cancer among women in the highest quartile of total energy intake compared to those in the lowest quartile (Q4 vs. Q1: OR = 1.6, 95 % CI: 1.3-2.0; P (trend) < 0.0001); these associations were limited to pre-menopausal women or women with hormone receptor-positive cancers. Although the associations were slightly stronger among women with a higher BMI or lower level of average lifetime physical activity, we observed a positive association between total energy intake and breast cancer risk across different strata of physical activity and BMI. Our results suggest that within sisters, high energy intake may increase the risk of breast cancer independent of physical activity and body size. If replicated in prospective studies, then these findings suggest that reductions in total energy intake may help in modifying breast cancer risk.

The alcohol dehydrogenase 1C(rs698) genotype and breast cancer: a meta-analysis

Published data regarding the association between alcohol dehydrogenase (ADH) 1C genotypes and breast cancer risk show conflicting results. The authors performed this meta-analysis on 1969 patients and 2244 controls from 4 (including 7 study populations) related case-control studies to estimate the association between ADH1C(rs698) genotyping information and breast cancer risk. According to the 6 eligible populations, the odds ratios (ORs) and 95% confidence intervals (CIs) for breast cancer risk for ADH1C (1-2) versus ADH1C (2-2) , ADH1C (1-1) versus ADH1C (2-2) genotype, and ADH1C (1) versus ADH1C (2) were 1.16 (0.95-1.42), 1.17 (0.95-1.44), and 1.05 (0.96-1.16), respectively. The OR (95% CI) for ADH1C (1-1) + ADH1C (1-2) versus ADH1C (2-2) from the 7 study populations was 1.14 (0.96-1.36). Meanwhile, genotypes of ADH1C (1-1) + ADH1C (1-2) increased the risk of breast cancer in drinkers (OR = 1.35; 95% CI = 1.03-1.76). This meta-analysis suggested that the ADH1C (1) allele might modestly influence the effect of alcohol on breast cancer but is not an independent risk factor for breast cancer. However, more restricted prospective studies are needed.

[Risk and protective factors for breast cancer: a systematic review]

This review aimed to investigate risk and protective factors for breast cancer and to analyze whether scientific evidence from the World Cancer Research Fund and American Institute for Cancer Research, published in 2007, was confirmed by new research. In May 2010 we reviewed cohort and case-control analytical studies from 2007 to 2010 in the PubMed, LILACS, and SciELO databases. We selected 27 articles (14 case-control and 13 cohort studies). Breastfeeding and physical activity were protective factors against breast cancer, and alcohol consumption was a risk factor. A direct proportional relationship was observed between larger waist circumference, weight throughout adulthood, and height and risk of breast cancer in postmenopausal women. The association between body fat and breast cancer is contradictory in both premenopausal and postmenopausal women. According to the accumulated evidence, breastfeeding and healthy lifestyle are the factors most strongly associated with breast cancer prevention.

Ethanol exposure induces the cancer-associated fibroblast phenotype and lethal tumor metabolism: implications for breast cancer prevention

Little is known about how alcohol consumption promotes the onset of human breast cancer(s). One hypothesis is that ethanol induces metabolic changes in the tumor microenvironment, which then enhances epithelial tumor growth. To experimentally test this hypothesis, we used a co-culture system consisting of human breast cancer cells (MCF7) and hTERT-immortalized fibroblasts. Here, we show that ethanol treatment (100 mM) promotes ROS production and oxidative stress in cancer-associated fibroblasts, which is sufficient to induce myofibroblastic differentiation. Oxidative stress in stromal fibroblasts also results in the onset of autophagy/mitophagy, driving the induction of ketone body production in the tumor microenvironment. Interestingly, ethanol has just the opposite effect in epithelial cancer cells, where it confers autophagy resistance, elevates mitochondrial biogenesis and induces key enzymes associated with ketone re-utilization (ACAT1/OXCT1). During co-culture, ethanol treatment also converts MCF7 cells from an ER(+) to an ER(-) status, which is thought to be associated with "stemness," more aggressive behavior and a worse prognosis. Thus, ethanol treatment induces ketone production in cancer-associated fibroblasts and ketone re-utilization in epithelial cancer cells, fueling tumor cell growth via oxidative mitochondrial metabolism (OXPHOS). This "two-compartment" metabolic model is consistent with previous historical observations that ethanol is first converted to acetaldehyde (which induces oxidative stress) and then ultimately to acetyl-CoA (a high-energy mitochondrial fuel), or can be used to synthesize ketone bodies. As such, our results provide a novel mechanism by which alcohol consumption could metabolically convert "low-risk" breast cancer patients to "high-risk" status, explaining tumor recurrence or disease progression. Hence, our findings have clear implications for both breast cancer prevention and therapy. Remarkably, our results also show that antioxidants [such as N-acetyl cysteine (NAC)] can effectively reverse or prevent ethanol-induced oxidative stress in cancer-associated fibroblasts, suggesting a novel strategy for cancer prevention. We also show that caveolin-1 and MCT4 protein expression can be effectively used as new biomarkers to monitor oxidative stress induced by ethanol.

SubpathwayMiner: a software package for flexible identification of pathways

With the development of high-throughput experimental techniques such as microarray, mass spectrometry and large-scale mutagenesis, there is an increasing need to automatically annotate gene sets and identify the involved pathways. Although many pathway analysis tools are developed, new tools are still needed to meet the requirements for flexible or advanced analysis purpose. Here, we developed an R-based software package (SubpathwayMiner) for flexible pathway identification. SubpathwayMiner facilitates sub-pathway identification of metabolic pathways by using pathway structure information. Additionally, SubpathwayMiner also provides more flexibility in annotating gene sets and identifying the involved pathways (entire pathways and sub-pathways): (i) SubpathwayMiner is able to provide the most up-to-date pathway analysis results for users; (ii) SubpathwayMiner supports multiple species (∼100 eukaryotes, 714 bacteria and 52 Archaea) and different gene identifiers (Entrez Gene IDs, NCBI-gi IDs, UniProt IDs, PDB IDs, etc.) in the KEGG GENE database; (iii) the system is quite efficient in cooperating with other R-based tools in biology. SubpathwayMiner is freely available at http://cran.r-project.org/web/packages/SubpathwayMiner/.

Alcohol and genetic polymorphisms: effect on risk of alcohol-related cancer

Public health guidelines aim to limit the consumption of alcoholic beverages worldwide and the subsequent health burden. In particular, alcohol consumption is an avoidable risk factor for cancer. In human beings, ethanol in alcoholic drinks is mainly oxidised in the liver by alcohol dehydrogenases to acetaldehyde, and is further detoxified to acetate by aldehyde dehydrogenases. Functional variants in genes involved in alcohol metabolism result in differences between individuals in exposure to carcinogenic acetaldehyde, suggesting a possible interaction of genetic susceptibility and alcohol exposure in cancer. We reviewed available studies of the combined effects of alcohol drinking and genetic polymorphisms on alcohol-related cancer risk. Most available data were for polymorphisms in alcohol and folate metabolism. We give an overview of published studies on the combined effects of alcohol drinking and polymorphisms in genes for alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), cytochrome P450 2E1, and methylene-tetrahydrofolate reductase on the risk of alcohol-related cancer. Current data lend support to a role of polymorphisms ADH1B and ALDH2 combined with alcohol consumption in cancer. Other available data are insufficient or inconclusive, highlighting the need for additional studies.

Double-strand breaks repair in lymphoblastoid cell lines from sisters discordant for breast cancer from the New York site of the BCFR

Unrepaired DNA double-strand breaks (DSBs) may have serious consequences for cells by inducing chromosomal aberrations, thereby increasing genetic instability and cancer risk. One's capacity to repair DSB is therefore an important factor to consider when estimating cancer risk. We assessed DNA end-joining (EJ) capacity in cell lines derived from sisters discordant for breast cancer to determine if individual differences in DSB repair are a significant risk factor. We used an in vitro phenotypic assay on nuclear extracts from lymphoblasts of 179 subjects including 86 cases and 93 controls. EJ activity was functionally estimated as the ability of extracts to join together monomers of the plasmid pUC18 linearized either with sticky (EcoRI) or blunt ends (HincII). Mean percentage of EJ capacity was slightly lower in cases than controls, both for EcoRI (cases 27.9 +/- 11.1; controls 29.6 +/- 10.7, P = 0.28) and HincII substrates (cases 28.8 +/- 12.2; controls 30.6 +/- 13.0, P = 0.36); however, no significant differences were observed. Categorizing EJ capacity into tertiles and using the highest activity as the referent, we observed elevated associations for each tertile of decreased repair [Odds ratio (OR) = 2.20, 95% confidence interval (CI) = 0.77-6.22 and OR = 4.22, 95% CI thinsp;= 1.22-14.0, P = 0.02], respectively, for EcoRI. Results were not statistically significant for HincII (OR = 1.37, 95% CI = 0.51-3.70 and OR = 2.32, 95% CI = 0.57-9.38, P = 0.24). These data suggest that individual differences in EJ capacity may represent a risk factor predisposing women to breast cancer.