Breast cancer risk and environmental exposures

Association of hormone receptors and human epidermal growth factor receptor-2/neu expressions with clinicopathologic factors of breast carcinoma: a cross-sectional study in a tertiary care hospital, Kabul, Afghanistan

BACKGROUND

Breast cancer (BC) is one of the major causes of death worldwide. It is the most common cause of death before the age of 70 years. The incidence and mortality of BC are rapidly increasing, posing great challenges to the health system and economy of every nation.

METHODOLOGY

A cross-sectional analytical study was conducted at the Department of Pathology and Clinical Laboratory of the French Medical Institute for Mothers and Children (FMIC) to demonstrate the association of human epidermal growth factor receptor 2 (Her2/Neu) and estrogen receptor (ER)/ progesterone receptor (PR) with clinical as well as pathological parameters among women with BC. A consecutive nonprobability sampling method was used for this study over a span of one and a half years.

RESULTS

One hundred twenty participants diagnosed with breast cancer were included in the study. The mean age at diagnosis was 44.58 ± 11.16 years. Out of the total patients, 68 (56.7%) were above 40 years old, 108 (90%) were married, 94 (78.3%) were multiparous, and 88 (73.3%) had a history of breastfeeding. 33.3% of cases were within the age range of menopause (40-50 years). The positive expression rates of ER, PR, and Her2/neu were found to be 48.8%, 44.6%, and 44.6%, respectively, and Her2/neu overexpression was found to be higher among ER/PR-negative cases.

CONCLUSION

In our study, we demonstrated that among Afghan women, grade II invasive ductal carcinoma, not otherwise specified, was the most common type of BC and frequently affected women above the age of 40. We also revealed that the percentage of negative ER (50.4%), negative PR (54.4%), and concordant ER/PR-negative cases were high compared to other possibilities. Additionally, the study revealed that expression of Her2/neu was in contrast with the expression of ER and PR receptors. The findings of our study still support the importance of performing immunohistochemical stains for hormonal receptor classification in terms of better clinical outcomes and prognosis.

The prevalence of ADSL (rs3788579) and CYP1A2 (rs17861162) polymorphisms in female breast cancer patients in North-West Iran

INTRODUCTION

Breast cancer is a prevalent and significant contributor to cancer-related mortality among women worldwide. Its increasing incidence, especially in regions like North-West Iran, necessitates a deeper understanding of genetic factors contributing to its development. Genetic alterations, particularly single nucleotide polymorphisms (SNPs), are implicated in breast cancer susceptibility, making investigation in this context crucial. This study explores the role of CYP1A2-rs17861162 and ADSL-rs3788579 SNPs in breast cancer risk among Iranian women.

METHODS

This study involved 200 female breast cancer patients and 200 healthy controls in North-West Iran. DNA was extracted from blood samples, and PCR-RFLP was used for genotyping the CYP1A2 and ADSL genes.

RESULTS

The CYP1A2-rs17861162 SNP exhibited a shift from the C allele to the G allele in breast cancer patients, resulting in a 21.7% decrease in CC genotype frequency and a 21.6% and 77.8% increase in CG and GG genotypes, respectively, compared to controls. In ADSL-rs3788579 SNP, breast cancer patients had a significantly higher prevalence of the T allele, with a 28.5% increase compared to controls. In healthy participants, CC was most common, while in the breast cancer group, TT was most common.

CONCLUSION

This study highlights significant genetic alterations in CYP1A2-rs17861162 and ADSL-rs3788579 SNPs among breast cancer patients in North-West Iran, suggesting their potential as diagnostic and prognostic biomarkers. Further research is warranted to elucidate the precise mechanisms underlying their contributions to breast cancer susceptibility in this population.

A Content Analysis of Social Support Messages about Environmental Breast Cancer Risk within Blogs for Mothers

Bloggers can help stimulate online conversations among their readers about a variety of health topics, including breast cancer. However, in previous studies, researchers have not specifically examined supportive messages within an online blogger community that stem from an intervention where bloggers were provided with evidence-based information about breast cancer risk that they could tailor and disseminate to their readers. In the current study, we content analyzed 282 supportive messages within online conversations from participants in blogger communities over a 2-month period immediately following an intervention where the authors provided 74 bloggers who write about motherhood issues with an infographic based on evidence-based information from the Breast Cancer and the Environment Research Program (BCERP) about environmental breast cancer risk/prevention. Bloggers who shared information about their personal breast cancer risk generated a significantly higher number of blog reader comments than bloggers who did not share information about their personal breast cancer risk. Bloggers who cited breast cancer statistics in posts were more likely to draw esteem and emotional support from their readers. Bloggers' repetition of information from blog intervention messages was more likely to elicit esteem, informational, and emotional support from readers. Disclosure of a personal breast cancer diagnosis was associated with mixed types of social support messages. The theoretical and practical implications are discussed along with key limitations of the study and future directions for research in this area.

Genomics of Particulate Matter Exposure Associated Cardiopulmonary Disease: A Narrative Review

Particulate matter (PM) exposure is associated with the development of cardiopulmonary disease. Our group has studied the adverse health effects of World Trade Center particulate matter (WTC-PM) exposure on firefighters. To fully understand the complex interplay between exposure, organism, and resultant disease phenotype, it is vital to analyze the underlying role of genomics in mediating this relationship. A PubMed search was performed focused on environmental exposure, genomics, and cardiopulmonary disease. We included original research published within 10 years, on epigenetic modifications and specific genetic or allelic variants. The initial search resulted in 95 studies. We excluded manuscripts that focused on work-related chemicals, heavy metals and tobacco smoke as primary sources of exposure, as well as reviews, prenatal research, and secondary research studies. Seven full-text articles met pre-determined inclusion criteria, and were reviewed. The effects of air pollution were evaluated in terms of methylation (n = 3), oxidative stress (n = 2), and genetic variants (n = 2). There is evidence to suggest that genomics plays a meditating role in the formation of adverse cardiopulmonary symptoms and diseases that surface after exposure events. Genomic modifications and variations affect the association between environmental exposure and cardiopulmonary disease, but additional research is needed to further define this relationship.

Polymorphisms in Phase I (CYP450) Genes CYP1A1 (rs4646421), CYP1B1 (rs1056836), CYP19A1 (rs749292) and CYP2C8 (rs1058930) and Their Relation to Risk of Breast Cancer: A Case-Control Study in Mazandaran Province in North of Iran

BACKGROUND:

The second leading cause of cancer-related death in women is breast cancer. Xenobiotic Metabolizing Enzymes (XMEs) contribute to the detoxification of numerous cancer therapy-induced products. In the metabolism of xenobiotic, cytochrome P450s or monooxygenases perform an important function by catalysing the hydroxylation reaction. In this study, the susceptibility and genetic polymorphisms of CYP450 isoenzymes was investigated that may have an etiological role in breast cancer.

AIM:

The main purpose of this study was to evaluate the association of CYP1A1 (rs4646421), CYP1B1 (rs1056836), CYP2C8 (rs1058930), and CYP19A1 (rs749292) polymorphisms with the risk of breast cancer in Mazandaran province.

MATERIAL AND METHODS:

This cross-sectional case-control study were recruited 72 patients and 51 healthy individuals and was performed between March 2018 to May 2018 in the Oncology Department at Imam Hospital in Sari city, Iran. Peripheral blood samples were collected in EDTA tube, and DNA extraction was performed using the salting-out method and WizPrep extraction kits. Breast cancer patients with known clinicopathological characters and healthy women as control group were genotyped for genes polymorphisms by PCR-RFLP technique, using restriction enzymes. Chi-square, Fisher exact test and Logistic regression model, were applied for statistical analysis.

RESULTS:

The results of the experiments showed that there was a significant relationship between two groups and the age of the patients is significantly higher than the control group (p = 0.044). According to the chi-square and Fisher exact test, education, pregnancy, menopause status and oppose were significant between the two groups. Based on using a logistic regression model in two normalized and age-adjusted models to finding relationship between the genotypes of each gene and breast cancer risk, it was determined that in the CYP2C8 genotype, those who have the CG allele have a 7.74 degree increased risk of breast cancer (CI = 95% 0.95-62.5) and in the CYP19A1 gene, individuals with GA genotype, increased risk of breast cancer (CI = %95 1.52-27.21), about the CYP1B1 gene, people with two genotypes of CG + GG had higher risk of breast cancer (CI = %95 1.19-5.71) and allele G has decreased risk of breast cancer in this gene (P = 0.0271), also allele G in CYP2C8 gene had the protective effect (P = 0.02). In the age-adjusted model, for the CYP2C8 gene, GG genotype increased risk of breast cancer (CI = %95 1.11-75.84) as well as, the CG + GG genotype in CYP1B1 gene (CI = %95 1.31-6.57).

CONCLUSION:

Our results confirm the association between CYP2C8 (rs1058930), CYP19A1 (rs749292) and CYP1B1 (rs1056836) gene polymorphisms and increased risk of breast cancer in women in Mazandaran province.

The LSP1 rs3817198 T > C polymorphism contributes to increased breast cancer risk: a meta-analysis of twelve studies

The association between the LSP1 rs3817198 T > C polymorphism and breast cancer risk has been widely investigated, but remains controversial. We therefore undertook a comprehensive meta-analysis to provide a high-quality evaluation of this association. A literature search was performed among Pubmed, EMBASE and Chinese National Knowledge Infrastructure (CNKI) databases prior to July 31, 2016, and the strength of the association between the LSP1 rs3817198 T > C polymorphism and breast cancer risk was assessed based on odds ratio (OR) and 95% confidence interval (95% CI). In total, 12 studies with 50,525 cases and 54,302 controls were included. Pooled risk estimates indicated a significant association between the LSP1 rs3817198 T > C polymorphism and breast cancer risk. Analysis of cases stratified based on ethnicity suggested that the association was significant in both Caucasian and Asian populations. Stratification based on source of controls revealed an association only in population-based studies. These findings indicate the LSP1 rs3817198 T > C polymorphism is associated with increased risk of breast cancer, especially in Caucasian and Asian populations. Large, well-designed studies with different ethnicities are still needed to verify our findings.

Significant Association of the MDM2 T309G Polymorphism with Breast Cancer Risk in a Turkish Population

Background:

Breast cancer is a leading cause of death in women worldwide. Genetic polymorphisms have been reported to be important etiological factors. Murine double minute 2 (MDM2) T309G interacts with p53 and mutations in p53 are present in approximately 50% of all cancers. However, it has been reported that effect of the polymorphism on breast cancer risk may vary in different populations. Here, we therefore investigated whether there is an association between MDM2 T309G (rs2279744) polymorphism and breast cancer in a Turkish population.

Materials and Methods:

We analysed 110 patients with breast cancer and 138 matched? controls. For genotyping, polymerase chain reaction and restriction length fragment polymorphism methods were used.

Results:

A significant difference was observed between case and control groups with regard to the distribution of the MDM2 T309G polymorphism (p<0.05). There was a significantly higher frequency of the TT genotype in the control group (p=0.028; OR, 2.42; 95% CI, 1.09-5.37). However, we did not find any relationships among tumor grade and metastasis status and this polymorphism.

Conclusion:

This study indicates that the MDM2 T309G polymorphism GG genotype and the TG+GG combination may be risk factors for breast cancer in our Turkish population.

FEN1 gene variants confer reduced risk of breast cancer in chinese women: A case-control study

This study aimed to assess the associations of two common Flap endonuclease 1 (FEN1) polymorphisms (rs4246215 and rs174538) with breast cancer risk in northwest Chinese women. We conducted a case-control study with 560 breast cancer patients and 583 age-matched healthy controls from Northwest China. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to estimate the associations. We found a significantly reduced risk of breast cancer associated with T allele of rs4246215 (allele model: OR 0.81, 95% CI 0.68–0.96; homozygote model: OR = 0.59, 95% CI = 0.40–0.87; recessive model: OR = 0.61, 95% CI = 0.42–0.89), especially in postmenopausal women (OR = 0.58, 95% CI = 0.35–0.97). Furthermore, the polymorphism showed a decreased association with larger tumor size (heterozygote model: OR = 0.63, 95% CI = 0.44–0.92; dominant model: OR = 0.63, 95% CI = 0.44–0.90). For rs174538, we did not find any difference in all genetic models. However, rs174538 was associated with lymph node metastasis (heterozygote model: OR = 0.57, 95% CI = 0.39–0.81; dominant model: OR = 0.61, 95% CI = 0.43–0.86) and estrogen receptor status (heterozygote model: OR = 1.50, 95% CI = 1.05–2.15; dominant model: OR = 1.42, 95% CI = 1.01–1.98). Haplotype analysis showed that T_rs4246215G_rs174538 haplotype was a protective factor of breast cancer (OR = 0.34, 95% CI = 0.14–0.81). Our results suggest that FEN1 polymorphisms may reduce the risk of breast cancer in Chinese women.

Investigation of Trace Elements in the Hair and Nail of Patients with Stomach Cancer

Trace metals are beneficial nutrient materials that act as essential cofactors in physiological processes. Recent evidence suggests that increase or decrease in certain trace metals may be related with risk and development of chronic diseases such as cancer. This study analyzed some trace elements level in hair and nail of patients with stomach cancer, and compared with their level in healthy controls. Trace elements (Cu, Fe, K, Li, Mg, Mn, Na, P, Se, Sr and Zn) are estimated in hair and nail of the 73 cancer patients and 83 controls by atomic absorption spectrophotometric method. The levels of Cu, K, Li, P and Se in hair and nail samples, were significantly higher in cases than controls. Levels of Mg and Sr were significantly lower in cases than controls. Fe level in hair samples was significantly higher in cases than controls. The mean concentrations of Fe, Se and P significantly increased with increasing cancer stage in the hair of patients. The average concentration of k also significantly increased with increasing cancer stage in the nail of patients. The results of our study show that there is an association between the increase in Cu, K, Li, P, Se and Fe, and stomach cancer development. Our results reveal that the increase in the trace elements could be a potential diagnostic marker to predict cancer progression and its etiology.

A prospective study of cancer risk among Agricultural Health Study farm spouses associated with personal use of organochlorine insecticides

BACKGROUND

Organochlorine insecticides (OCs) have historically been used worldwide to control insects, although most have now been banned in developed countries. Evidence for an association between OC exposures and cancer predominantly comes from occupational and population based-studies among men. We evaluated the association between the use of specific OCs and cancer among the female spouses of pesticide applicators in the Agricultural Health Study.

METHODS

At enrollment (1993-1997), spouses of private applicators in the cohort provided information about their own use of pesticides, including seven OCs (aldrin, chlordane, dieldrin, DDT, heptachlor, lindane, and toxaphene), and information on potential confounders. We used Poisson regression to estimate relative risks (RRs) and 95% confidence intervals (CIs) for cancers (n ≥ 3 exposed cases) reported to state cancer registries from enrollment through 2012 (North Carolina) and 2013 (Iowa), and use of the individual OCs, as well as use of any of the specific OCs.

RESULTS

Among 28,909 female spouses, 2191 (7.58%) reported ever use of at least one OC, of whom 287 were diagnosed with cancer. Most cancers were not associated with OC use. Risk of glioma was increased among users of at least one OC (Nexposed = 11, RR = 3.52, 95% CI 1.72-7.21) and specifically among lindane users (Nexposed = 3, RR = 4.45, 95% CI 1.36-14.55). Multiple myeloma was associated with chlordane (Nexposed = 6, RR = 2.71, 95% CI 1.12-6.55). Based on 3 exposed cases each, there were also positive associations between pancreatic cancer and lindane, and ER-PR- breast cancer and dieldrin. No other associations with breast cancer were found.

CONCLUSIONS

Overall, there were some associations with OC use and cancer incidence, however we were limited by the small number of exposed cancer cases. Future research should attempt to expand on these findings by assessing environmental sources of OC exposures, to fully evaluate the role of OC exposures on cancer risk in women.

The Evaluation of p53 Polymorphism at Codon 72 and Association With Breast Cancer in Iran: A Systematic Review and Meta-analysis

Background

Breast cancer is the most common cancer among women in Iran and the world. Multiple environmental factors and genetic variations such as genetic polymorphisms are of its main causes. p53 gene plays an important role in conserving and sustaining the genome as a tumor suppressing gene. Change and polymorphism at codon 72 of p53 gene are correlated with increased risk of lung, mouth, endometrial, prostate, and colorectal cancers, and could be considered an indicator of susceptibility to breast cancer.

Methods

Twelve studies (1,190 cases and 1,145 control studies with evaluation of three types of Arg/Arg, Arg/Pro, and Pro/Pro genotypes) have been conducted using keywords, such as polymorphism at codon 72, gene p53 polymorphisms, and the relation between polymorphisms and breast cancer, from databases in Iran, including Magiran, Medlibe, Sid, and Iranmedex, as well as Latin databases such as PubMed, Google Scholar, Science Direct, and Scopus.

Results

The OR for Arg/Arg is 1.58 (95% CI: 2.45 to 1.01), the OR for Arg/Pro is 0.75 (95% CI: 1.10 to 0.51), and the OR for Pro/Pro is 0.62 (95% CI: 0.93 to 0.42). p53 gene polymorphism at codon 72 is statistically significant in Arg/Arg and Pro/Pro genotypes.

Conclusions

Arg/Arg genotype can be considered as a risk factor for breast cancer, and Pro/Pro genotype can be accounted for as a protective factor against breast cancer.

Genetic polymorphisms of phase I metabolizing enzyme genes, their interaction with lifetime grilled and smoked meat intake, and breast cancer incidence

PURPOSE

To examine associations between 22 CYP single nucleotide polymorphisms (SNPs) and breast cancer incidence and their interactions with grilled-smoked meat intake, a source of polycyclic aromatic hydrocarbons.

METHODS

White women with first primary in situ or invasive breast cancer (n = 988) and frequency-matched controls (n = 1021) from a population-based study were interviewed to assess lifetime grilled-smoked meat intake. SNPs with minor allele frequencies of greater than 0.05 were selected because of their links to carcinogenesis. We used multivariable unconditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Breast cancer was inversely associated with CYP1A1 rs104C8943 AG + GG genotype (OR = 0.71, 95% CI = 0.50-0.99; vs. AA genotype) and positively associated with CYP1B1 rs10175338 TT genotype (OR = 1.59, 95% CI = 1.12-2.26; vs. GG genotype) and the CYP3A4 rs2242480 CT + TT genotype (OR = 1.25, 95% CI = 1.00-1.56; vs. CC genotype). The sum of the number of "at-risk" alleles for the CYP SNPs was positively associated with breast cancer incidence (4-6 "at-risk" alleles OR = 2.33, 95% CI = 1.37-3.99 vs. 0-1 alleles; P_Trend < .01). We observed multiplicative and additive interactions (P < .05) between grilled-smoked meat intake (low vs. high) with CYP1A1 rs1048943 and CYP1B1 rs10175338 SNPs.

CONCLUSIONS

Phase I metabolizing enzyme gene SNPs may play a role in breast cancer development and may modify the grilled-smoked meat intake-breast cancer association.

Breast cancer and persistent organic pollutants (excluding DDT): a systematic literature review

Persistent organic pollutants (POPs) are a group of heterogeneous compounds of both natural and anthropogenic origin with highly persistent and bioaccumulative properties. They cause a range of adverse effects to human health and the environment around the world. There is growing concern that POPs may increase breast cancer risk due to their xenoestrogenic properties. The aim of this systematic literature review is to summarize and integrate the risks of breast cancer following environmental exposure to POPs (other than DDT) from primary epidemiological studies published between 2006 and 2015. After searching various databases, 14 case-control studies and one cohort study were included. Evidence of an association between increased breast cancer risk and environmental exposure to these chemicals is inconsistent and inadequate to conclude with certainty. However, most of the studies have examined exposure to the pollutants after diagnosis of breast cancer, overlooking exposure during critical windows of vulnerability. They have also largely focused on individual chemicals but ignored the combined effects of different chemicals. Therefore, major data gaps remain in examining exposure during critical windows of vulnerability and assessing combined effects of multiple chemicals. Development of better exposure assessment methods addressing these gaps is required for future research.

Risks of developing breast and colorectal cancer in association with incomes and geographic locations in Texas: a retrospective cohort study

BACKGROUND

No study has been conducted to investigate the spatial pattern and association of socioeconomic status (such as income) with breast and colorectal cancer incidence in Texas, United States. This study aimed to determine whether median household income was associated with the risk of developing breast and colorectal cancer in Texas and to identify higher cancer risks by race/ethnicity and geographic areas.

METHODS

This was a retrospective cohort study with an ecological component in using aggregated measures at the county level. We identified 243,677 women with breast cancer and 155,534 men and women with colorectal cancer residing in 254 counties in Texas in 1995-2011 from the public-use dataset of Texas Cancer Registry. The denominator population and median household income at the county level was obtained from the U.S. Bureau of the Census. Cancer incidence rates were calculated as number of cases per 100,000 persons and age-adjusted using the 2000 US population data. We used the ArcGIS v10.1 (geographic information system software) to identify multiple clustered counties with high and low cancer incidences in Texas.

RESULTS

Age-adjusted breast cancer incidence rate in the highest median income quintile group was 151.51 cases per 100,000 in 2008-2011 as compared to 98.95 cases per 100,000 in the lowest median income quintile group. The risk of colorectal cancer appeared to decrease with increasing median income in racial/ethnic population. Spatial analysis revealed the significant low breast cancer incidence cluster regions located in southwest US-Mexico border counties in Texas.

CONCLUSIONS

This study demonstrated that higher income was associated with an increased risk of breast cancer and a decreased risk of colorectal cancer in Texas. There were geographic variations with cancer incidence clustered in high risk areas in Texas. Future studies may need to explore more factors that might explain income and cancer risk associations and their geographic variations.

Association between TCF7L2 polymorphisms and breast cancer susceptibility: a meta-analysis

AIM

Our aim was to investigate the relationship between transcription factor 7-like 2 (TCF7L2) polymorphisms and breast cancer susceptibility.

METHODS

PubMed, Embase and CNKI databases were used to search the related studies investigating the correlation between TCF7L2 polymorphisms and breast cancer susceptibility. Pooled ORs and 95% CIs, based on five genetic models, were applied to estimate the association betweenTCF7L2 polymorphisms and breast cancer. A fixed-effect model or a random-effect model was applied according to the between-study heterogeneity.

RESULTS

We analyzed six single nucleotide polymorphisms (SNPs) in TCF7L2 gene, namely rs12255372, rs7903146, rs7900150, rs3750805, rs1225404 and rs7003146. The increased risk of breast cancer was associated with TCF7L2 polymorphisms (22 vs. 11: OR=1.16, 95% CI=1.02-1.32; 22+12 vs. 11: OR=1.06, 95% CI=1.02-1.10; 22 vs. 11+12: OR=1.15, 95% CI=1.04-1.27; 2 vs. 1: OR=1.07, 95% CI=1.02-1.13; 12 vs. 11: OR=1.05, 95% CI=1.01-1.09). Among the locus, rs7903146 polymorphism was significantly associated with the risk for breast cancer under five genetic models (TT vs. CC: OR=1.29, 95% CI=1.08-1.53; TT+CT vs. CC: OR=1.09, 95% CI=1.01-1.18; TT vs. CC+CT: OR=1.24, 95% CI=1.05-1.48; T vs. C: OR=1.11, 95% CI=1.04-1.19; CT vs. CC: OR=1.08, 95% CI=1.00-1.17). Additionally, rs7900150 also showed effects on the susceptibility of breast cancer (TT vs. AA: OR=1.22, 95% CI=1.07-1.39; TT+AT vs. AA: OR=1.06, 95% CI=1.00-1.14; TT vs. AA+AT: OR=1.21, 95% CI=1.07-1.37; T vs. A: OR=1.09, 95% CI=1.02-1.15; AT vs. AA: OR=1.04, 95% CI=1.01-1.33). Meanwhile, we found that rs3750805 polymorphism could increased the risk for breast cancer (TT+AT vs. AA: OR=1.12, 95% CI=1.01-1.24).

CONCLUSION

Our meta-analysis demonstrates that TCF7L2 polymorphisms may increase the risk for breast cancer.

The association between deficient manganese levels and breast cancer: a meta-analysis

There are conflicting reports on the correlation between manganese (Mn) levels and breast cancer. The purpose of the present study is to clarify the association between Mn levels and breast cancer using a meta-analysis approach. We searched articles indexed in Pubmed and the Chinese Journal Full-text Database (CJFD) published as of August 2014 that met our predefined criteria. Eleven eligible studies involving 1302 subjects were identified. Overall, pooled analysis indicated that subjects with breast cancer had lower Mn levels than the healthy controls (SMD = -1.51, 95% CI = [-2.47, -0.56]). Further subgroup analysis found a similar pattern in China (SMD = -1.32, 95% CI = [-2.33, -0.32]) and Korea (SMD = -4.08, 95% CI = [-4.63, -3.54]), but not in Turkey (SMD = -0.96, 95% CI = [-3.19, 1.27]). Further subgroup analysis also found a similar pattern in different sample specimens (serum: SMD = -1.24, 95% CI = [-2.31, -0.16]; hair: SMD = -1.99, 95% CI = [-3.91, -0.06]) and different types of Mn measurement (inductively coupled plasma-atomic absorption spectrometry (ICP-AAS): SMD = -1.14, 95% CI = [-2.24, -0.04]; graphite furnace atomic absorption spectroscopy (GFAAS): SMD = -1.94, 95% CI = [-2.38, -1.49]; inductively coupled plasma-atomic emission spectrometry (ICP-AES): SMD = -3.77, 95% CI = [-4.70, -2.85]). No evidence of publication bias was observed. In conclusion, this meta-analysis supports a significant association between deficient Mn levels and breast cancer. However, the subgroup analysis found that there was contradiction regarding races and geography, like China and Turkey. Thus this finding needs further confirmation by trans-regional multicenter, long-term observation in a cohort design to obtain better understanding of causal relationships between Mn levels and breast cancer, through measuring Mn at baseline to investigate whether the highest Mn category versus lowest was associated with breast cancer risk.

F344/NTac Rats Chronically Exposed to Bromodichloroacetic Acid Develop Mammary Adenocarcinomas With Mixed Luminal/Basal Phenotype and Tgfβ Dysregulation

Breast cancer is the most common cancer and the second-leading cause of cancer mortality in women in the United States. A recent 2-year National Toxicology Program carcinogenicity study showed an increased incidence of proliferative mammary lesions (hyperplasia, fibroadenoma, adenocarcinoma) in F344/NTac rats exposed to bromodichloroacetic acid (BDCA), a disinfection by-product in finished drinking water with widespread human exposure. We hypothesized that the increase in mammary tumors observed in BDCA-exposed F344/NTac rats may be due to underlying molecular changes relevant for human breast cancer. The objective of the study was to compare (1) gene and protein expression and (2) mutation spectra of relevant human breast cancer genes between normal untreated mammary gland and mammary tumors from control and BDCA-exposed animals to identify molecular changes relevant for human cancer. Histologically, adenocarcinomas from control and BDCA-exposed animals were morphologically very similar, were estrogen/progesterone receptor positive, and displayed a mixed luminal/basal phenotype. Gene expression analysis showed a positive trend in the number of genes associated with human breast cancer, with proportionally more genes represented in the BDCA-treated tumor group. Additionally, a 5-gene signature representing possible Tgfβ pathway activation in BDCA-treated adenocarcinomas was observed, suggesting that this pathway may be involved in the increased incidence of mammary tumors in BDCA-exposed animals.

Effects of environmental organochlorine pesticides on human breast cancer: putative involvement on invasive cell ability

Human exposure to persistent organic pollutants (POPs) is a certainty, even to long banned pesticides like o,p'-dichlorodiphenyltrichloroethane (o,p'-DDT), and its metabolites p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), and p,p'-dichlorodiphenyldichloroethane (p,p'-DDD). POPs are known to be particularly toxic and have been associated with endocrine-disrupting effects in several mammals, including humans even at very low doses. As environmental estrogens, they could play a critical role in carcinogenesis, such as in breast cancer. With the purpose of evaluating their effect on breast cancer biology, o,p'-DDT, p,p'-DDE, and p,p'-DDD (50-1000 nM) were tested on two human breast adenocarcinoma cell lines: MCF-7 expressing estrogen receptor (ER) α and MDA-MB-231 negative for ERα, regarding cell proliferation and viability in addition to their invasive potential. Cell proliferation and viability were not equally affected by these compounds. In MCF-7 cells, the compounds were able to decrease cell proliferation and viability. On the other hand, no evident response was observed in treated MDA-MB-231 cells. Concerning the invasive potential, the less invasive cell line, MCF-7, had its invasion potential significantly induced, while the more invasive cell line MDA-MB-231, had its invasion potential dramatically reduced in the presence of the tested compounds. Altogether, the results showed that these compounds were able to modulate several cancer-related processes, namely in breast cancer cell lines, and underline the relevance of POP exposure to the risk of cancer development and progression, unraveling distinct pathways of action of these compounds on tumor cell biology.

Hazardous air pollutants and breast cancer risk in California teachers: a cohort study

BACKGROUND

Studies suggest that higher breast cancer rates in urban areas persist after accounting for the prevalence of known risk factors, leading to speculation that urban environmental exposures, such as air pollution, may play a role in the etiology of breast cancer. Combining modeled ambient air concentrations with data from a large prospective cohort of California women with over 15 years of follow-up, we examined the relationship between breast cancer incidence and modeled concentrations of air pollutants shown to be mammary gland carcinogens (MGCs).

METHODS

The study population of 112,378 California Teachers Study participants included 5,676 women diagnosed with invasive breast cancer. Modeled annual average ambient air concentrations of 24 MGCs from the U.S. Environmental Protection Agency were linked to participants' addresses. Cox proportional hazards models were used to estimate hazard rate ratios and 95% confidence intervals associated with residential MGC levels. MGCs were examined individually and as a combined summary variable for all participants, in selected subsets, and by tumor hormone responsiveness.

RESULTS

Initial models yielded some evidence for increased risk for several compounds, including acrylamide, carbon tetrachloride, chloroprene, 4,4'-methylene bis(2-chloroaniline), propylene oxide, and vinyl chloride, but after adjustment for multiple comparisons, only results for propylene oxide and vinyl chloride remained statistically significant. In subset analyses, estrogen-receptor positive or progesterone-receptor positive (ER+/PR+) tumors were associated with higher ambient levels of acrylamide, benzidine, carbon tetrachloride, ethylidene dichloride, and vinyl chloride, while ER-/PR- tumors were associated with higher ambient levels of benzene. Interesting results for different compounds were observed within certain subsets of the population.

CONCLUSION

While our initial models yielded several elevated risk estimates, after adjusting for multiple comparisons and breast cancer risk factors, most hazard ratios were no longer statistically significant. Our subset analyses, however, suggest that elevated risk may be associated with some compounds for certain subgroups of interest. A summary variable for all 24 MGCs did not offer any advantage over the models for individual compounds. Results must be interpreted cautiously, as estimated exposure was limited to modeled annual average ambient air concentrations, and could not account for other sources or routes other than inhalation.

Association of the three common SNPs of cyclooxygenase-2 gene (rs20417, rs689466, and rs5275) with the susceptibility of breast cancer: an updated meta-analysis involving 34,590 subjects

Several single nucleotide polymorphisms have been identified in cyclooxygenase-2 (COX-2) genes (e.g., −765 G>C (rs20417), −1195G>A (rs689466), and 8473 C>T (rs5275)). The association of these SNPs with the risk of different cancer types is still controversial. This study aims to evaluate the correlation between these SNPs and breast cancer risk in different ethnic groups. We have searched PubMed, Web of Knowledge, and Embase for relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the strength of the associations. A total of 13 studies (15,330 cases and 19,260 controls) were eligible for meta-analysis. This meta-analysis showed that COX-2 rs20417 polymorphism was correlated with an increased risk of breast cancer in Caucasians, while rs689466 was associated with a decreased risk of breast cancer in Caucasians. The rs5275 polymorphism had no association with breast cancer risk.

Association between MDM2 rs 2279744 polymorphism and breast cancer susceptibility: a meta-analysis based on 9,788 cases and 11,195 controls

Purpose

Previous studies have suggested associations between MDM2 (mouse double minute 2 homolog) polymorphisms and cancer risk. The aim of this study was to evaluate the relationship between the MDM2 rs 2279744 polymorphism and the susceptibility of breast cancer.

Methods

We searched PubMed, Web of Knowledge, Embase, and the Chinese National Knowledge Infrastructure (CNKI) database for case–control studies published up to October 2013 that investigated MDM2 rs 2279744 polymorphism and breast cancer risk. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of these associations.

Results

A total of 19 studies were identified for the meta-analysis, including 9,788 cases and 11,195 controls. The variant heterozygote (TG) was associated with breast cancer risk in the overall population (TG vs TT: OR =1.10, 95% CI =1.04–1.17, P=0.001, P=0.23 for heterogeneity test). In the subgroup analyses by ethnicity, a significantly increased risk was observed among Asians (G vs T: OR =1.12, 95% CI =1.02–1.23, P=0.02, P_het=0.04; GG vs TT: OR =1.29, 95% CI =1.06–1.56, P=0.01, P_het=0.04; TG vs TT: OR =1.36, 95% CI =1.15–1.60, P=0.0004, P_het=0.45; dominant model TG+GG vs TT: OR =1.21, 95% CI =1.03–1.41, P=0.02, P_het=0.07). However, among Caucasians, rs 2279744 was associated with breast cancer risk in only one genotype (TG vs TT: OR =1.09, 95% CI =1.00–1.18, P=0.04, P_het=0.37). No publication bias was found in the present study.

Conclusion

This meta-analysis provides evidence for the association between the MDM2 rs 2279744 polymorphism and breast cancer susceptibility. The results suggest that the MDM2 rs 2279744 polymorphism plays an important role in breast cancer, especially in Asians.

Histone lysine trimethylation or acetylation can be modulated by phytoestrogen, estrogen or anti-HDAC in breast cancer cell lines

AIM

The isoflavones genistein, daidzein and equol (daidzein metabolite) have been reported to interact with epigenetic modifications, specifically hypermethylation of tumor suppressor genes. The objective of this study was to analyze and understand the mechanisms by which phytoestrogens act on chromatin in breast cancer cell lines.

MATERIALS & METHODS

Two breast cancer cell lines, MCF-7 and MDA-MB 231, were treated with genistein (18.5 µM), daidzein (78.5 µM), equol (12.8 µM), 17β-estradiol (10 nM) and suberoylanilide hydroxamic acid (1 µM) for 48 h. A control with untreated cells was performed. 17β-estradiol and an anti-HDAC were used to compare their actions with phytoestrogens. The chromatin immunoprecipitation coupled with quantitative PCR was used to follow soy phytoestrogen effects on H3 and H4 histones on H3K27me3, H3K9me3, H3K4me3, H4K8ac and H3K4ac marks, and we selected six genes (EZH2, BRCA1, ERα, ERβ, SRC3 and P300) for analysis.

RESULTS

Soy phytoestrogens induced a decrease in trimethylated marks and an increase in acetylating marks studied at six selected genes.

CONCLUSION

We demonstrated that soy phytoestrogens tend to modify transcription through the demethylation and acetylation of histones in breast cancer cell lines.

Estimating lifetime risk from spot biomarker data and intraclass correlation coefficients (ICC)

Human biomarker measurements in tissues including blood, breath, and urine can serve as efficient surrogates for environmental monitoring because a single biological sample integrates personal exposure across all environmental media and uptake pathways. However, biomarkers represent a "snapshot" in time, and risk assessment is generally based on long-term averages. In this study, a statistical approach is proposed for estimating long-term average exposures from distributions of spot biomarker measurements using intraclass correlations based upon measurement variance components from the literature. This methodology was developed and demonstrated using a log-normally distributed data set of urinary OH-pyrene taken from our own studies. The calculations are generalized for any biomarker data set of spot measures such as those from the National Health and Nutrition Evaluation Studies (NHANES) requiring only spreadsheet calculations. A three-tiered approach depending on the availability of metadata was developed for converting any collection of spot biomarkers into an estimated distribution of individual means that can then be compared to a biologically relevant risk level. Examples from a Microsoft Excel-based spreadsheet for calculating estimates of the proportion of the population exceeding a given biomonitoring equivalent level are provided as an appendix.

Trace elements and heavy metals in hair of stage III breast cancer patients

This prospective study was designed to compare the hair levels of 36 elements in 52 patients with stage III breast cancer to those of an equal number of healthy individuals. Principal component and cluster analysis were used for source of identification and apportionment of heavy metals and trace elements in these two groups. A higher average level of iron was found in samples from patients while controls had higher levels of calcium. Both patients and controls had elevated levels of tin, magnesium, zinc, and sodium. Almost all element values in cancer patients showed higher dispersion and asymmetry than in healthy controls. Between the two groups, there were statistically significant differences in the concentrations of silver, arsenic, gold, boron, barium, beryllium, calcium, cadmium, cerium, cobalt, cesium, gadolinium, manganese, nickel, lead, antimony, scandium, selenium, and zinc (p < 0.05). Strong positive correlations were found between lead and gold (r = 0.785) in the cancer group and between palladium and cobalt (r = 0.945) in the healthy individuals. Our results show that there are distinct patterns of heavy metals and trace elements in the hair of breast cancer patients in comparison to healthy controls. These results could be of significance in the diagnosis of breast cancer.

Uterine leiomyomata in a cohort of Great Lakes sport fish consumers

Diet and endocrine disrupting persistent organic pollutants (POPs) have been associated with gynecologic conditions including uterine leiomyomata (UL), endometriosis, and ovarian cysts. Great Lakes sport fish consumption is a source of exposure to POPs such as p,p'-diphenyldichloroethene (DDE) and polychlorinated biphenyls (PCBs). This study was designed to examine retrospectively the effects Great Lakes sport fish consumption on the incidence of UL and to examine the effects of DDE and PCB serum levels on prevalent UL in women participating in the Great Lakes Fish Consumption Study. We hypothesized that associations of exposures with UL would be modified by breastfeeding status. Years of sport fish consumption, demographic, health, and reproductive data were assessed by survey. In a subgroup, serum was collected and tested for DDE and PCB levels. Effects of years of Great Lakes sport fish and sport fish consumption were modeled using time-dependent Cox proportional hazards regression and effects of POP exposures on UL were modeled using multiple logistic regression. Years of sport fish consumption were associated with UL, with an incidence rate ratio of 1.2 (95% CI 1.0-1.3) for each 10-year increment of fish consumption. Summary measures of POP exposures in the overall group were not associated with UL. In the subgroup of women who never breastfed and in whom PCB measurements were available, however, UL was significantly associated with PCBs and groupings of estrogenic, antiestrogenic, and dioxin-like PCBs. These findings support the possibility that PCB exposures from fish consumption may increase the risk of UL and highlight the importance of additional studies exploring biologic pathways by which they could be acting.

The xenoestrogen bisphenol A inhibits postembryonic vertebrate development by antagonizing gene regulation by thyroid hormone

Bisphenol A (BPA), a chemical widely used to manufacture plastics, is estrogenic and capable of disrupting sex differentiation. However, recent in vitro studies have shown that BPA can also antagonize T(3) activation of the T(3) receptor. The difficulty in studying uterus-enclosed mammalian embryos has hampered the analysis on the direct effects of BPA during vertebrate development. This study proposed to identify critical T(3) pathways that may be disrupted by BPA based on molecular analysis in vivo. Because amphibian metamorphosis requires T(3) and encompasses the postembryonic period in mammals when T(3) action is most critical, we used this unique model for studying the effect of BPA on T(3)-dependent vertebrate development at both the morphological and molecular levels. After 4 d of exposure, BPA inhibited T(3)-induced intestinal remodeling in premetamorphic Xenopus laevis tadpoles. Importantly, microarray analysis revealed that BPA antagonized the regulation of most T(3)-response genes, thereby explaining the inhibitory effect of BPA on metamorphosis. Surprisingly, most of the genes affected by BPA in the presence of T(3) were T(3)-response genes, suggesting that BPA predominantly affected T(3)-signaling pathways during metamorphosis. Our finding that this endocrine disruptor, well known for its estrogenic activity in vitro, functions to inhibit T(3) pathways to affect vertebrate development in vivo and thus not only provides a mechanism for the likely deleterious effects of BPA on human development but also demonstrates the importance of studying endocrine disruption in a developmental context in vivo.

Breast cancer, dermatofibromas and arsenic

BACKGROUND

Dermatofibromas are common benign tumors in women, and breast cancer is the most common malignancy in women. The aim of this study is to determine if there is any relationship between the two conditions.

MATERIALS AND METHODS

Five patients with dermatofibromas and 10 control patients (two groups) had their skin biopsies measured for arsenic by inductively coupled mass spectrometry. Fifty randomly selected patients with breast cancer and 50 control patients were examined for the presence of dermatofibromas.

RESULTS

The dermatofibromas were found to have an arsenic concentration of 0.171 micrograms/gram, compared with 0.06 and 0.07 micrograms/gram of the two control groups. Forty-three out of 50 patients with breast cancer had dermatofibromas and 32/50 patients with breast cancer had multiple dermatofibromas, compared to 10/50 control patients with dermatofibromas and only 1/50 with multiple dermatofibromas.

CONCLUSIONS

Arsenic is important in the development of dermatofibromas and dermatofibromas represent a reservoir and important sign of chronic arsenic exposure. Dermatofibromas represent an important sign for women at risk for breast cancer, and arsenic may represent the cause of the majority of cases of breast cancer.

Dieldrin promotes resistance to anoikis in breast cancer cells in vitro

Epidemiological evidence suggests that exposure to the pesticide dieldrin, is associated with increased risk of breast cancer and mortality. We hypothesize that dieldrin promotes breast cancer by increasing survival of breast cancer cells. The aims of this study were to measure the effect of dieldrin on survival of breast cancer cells and the expression of tyrosine kinase B (TrkB), a suppressor of anoikis (apoptosis triggered by inappropriate anchorage). The human breast cancer cell line MDA-MB-231 was treated with dieldrin and proliferation, viability and resistance to anoikis were measured. TrkB expression was measured by Western blot in lysates and by immunohistochemistry in human tissue specimens. Dieldrin increased resistance to anoikis and TrkB expression. TrkB was expressed in a subset of high-grade breast carcinoma specimens. Our results demonstrate that dieldrin increases resistance to anoikis and expression of TrkB and show for the first time TrkB protein expression in human breast cancer.

Mixture effects of estrogenic compounds on proliferation and pS2 expression of MCF-7 human breast cancer cells

Humans are exposed to a variety of food-borne phytochemicals (PC) as well as synthetic chemicals (SC). Some of these compounds have been reported to have estrogenic or anti-estrogenic properties and are therefore suspected endocrine disruptors. Until now it remains unclear if non-additive effects occur in combinations with endogenous estrogens, such as 17beta-estradiol (E(2)). To investigate such interactions, several PC and SC were tested individually, in mixtures and as combinations of mixtures with E(2) for effects on ERalpha receptor mediated cell proliferation and estrogen regulated pS2 expression level in MCF-7(bus) cells. PCs (coumestrol, genistein, naringenin, catechin, epicatechin, quercetin) or SCs (4-nonylphenol, octylphenol, beta-hexachlorocyclohexane, bisphenol A, methoxychlor, dibutyl phthalate) were mixed (PCmix and SCmix) either in concentrations reflecting human serum concentrations or at equipotent concentrations for estrogenicity. EC(50) values were applied in two approaches of the concentration-addition model (the method of isoboles and the cumulative estrogen equivalency method) to assess mixture effects. In both models PCmix and SCmix or combinations of the mixtures with E(2) showed no departure from additivity. In conclusion, the tested PCs and SCs appeared to act as (full) agonists for the estrogen receptor and interacted in mixtures and with estradiol in an additive way. In addition, it is concluded that the possible contribution of food-borne PCs to the estrogenic effect of xenobiotics is likely to be more significant than that caused by food-borne SCs.

Selenium in serum and neoplastic tissue in breast cancer: correlation with CEA

Trace element selenium (Se) is regarded to be a breast cancer preventive factor involved in multiple protective pathways. In all, 80 women with breast cancer who underwent a radical mastectomy were enrolled in the study. Serum Se and carcinoembryonic antigen levels were measured using a fluorometric and IRMA assay, respectively. Se tissue concentration was determined by a tissue extracting fluorometric assay. For statistical analysis purposes t-test was used and P-values <0.001 were regarded as statistically significant. Serum Se was 42.5±7.5 μg l⁻¹ in breast cancer patients and 67.6±5.36 μg l⁻¹ in the age-matched control group of healthy individuals. Serum carcinoembryonic antigen in patients was 10±1.7 U ml⁻¹ (normal <2.5 U ml⁻¹ in nonsmokers/<3.5 U ml⁻¹ in smokers). A statistically significant difference was found for both serum Se and CEA between two groups studied (P<0.001). Neoplastic tissue Se concentration was 2660±210 mg g⁻¹ tissue; its concentration in the adjacent non-neoplastic tissue was 680±110 mg g⁻¹ tissue (P<0.001). An inverse relationship between Se and CEA serum levels was found in the two groups studied (r=−0.794). There was no correlation between serum/tissue Se concentration and stage of the disease. The decrease in serum Se concentration as well as its increased concentration in the neoplastic breast tissue is of great significance. These alterations may reflect part of the defence mechanisms against the carcinogenetic process.

Polymorphisms in the MDM2 promoter and risk of breast cancer: a case-control analysis in a Chinese population

MDM2 is a phosphoprotein that interacts with P53 and inhibits its activity. Recently, a T/G substitution (SNP309) in the promoter of MDM2 was identified and has been demonstrated to be associated with an increased MDM2 expression and a significantly earlier age of onset of several tumors, including breast cancer. To test the hypothesis that this functional variant in the MDM2 promoter is associated with risk of breast cancer, we conducted a molecular epidemiological study of 366 breast cancer cases (BC), 263 patients with benign breast diseases (BBD) and 605 cancer-free controls in China, in which we genotyped this T/G variant and another common insertion/deletion polymorphism (Del1518) in the MDM2 promoter and evaluated the associations between these two polymorphisms and breast cancer risk. We found that the variant allele frequencies of these two polymorphisms were not statistically different between the cases and controls (SNP309G: 0.500, 0.542, and 0.506 in BC, BBD, and controls, respectively, and Del1518-: 0.296, 0.308, and 0.297 in BC, BBD, and controls, respectively). Logistic regression analyses revealed that the variant genotypes of both MDM2 SNP309 and Del1518 polymorphisms were not significantly associated with risk of breast cancer (adjusted OR, 1.03; 95% CI, 0.74-1.42 for SNP309 TG and GG; and adjusted OR, 1.09; 95% CI, 0.83-1.43 for Del1518 +/- and -/-). These findings suggest that these two MDM2 promoter variants may not play a major role in the etiology of breast cancer.

Residential proximity to agricultural pesticide use and incidence of breast cancer in California, 1988-1997

California is the largest agricultural state in the United States and home to some of the world's highest breast cancer rates. The objective of our study was to evaluate whether California breast cancer rates were elevated in areas with recent high agricultural pesticide use. We identified population-based invasive breast cancer cases from the California Cancer Registry for 1988-1997. We used California's pesticide use reporting data to select pesticides for analysis based on use volume, carcinogenic potential, and exposure potential. Using 1990 and 2000 U.S. Census data, we derived age- and race-specific population counts for the time period of interest. We used a geographic information system to aggregate cases, population counts, and pesticide use data for all block groups in the state. To evaluate whether breast cancer rates were related to recent agricultural pesticide use, we computed rate ratios and 95% confidence intervals using Poisson regression models, adjusting for age, race/ethnicity, and neighborhood socioeconomic status and urbanization. This ecologic (aggregative) analysis included 176,302 invasive breast cancer cases and 70,968,598 person-years of observation. The rate ratios did not significantly differ from 1 for any of the selected pesticide categories or individual agents. The results from this study provide no evidence that California women living in areas of recent, high agricultural pesticide use experience higher rates of breast cancer.

Transcriptional signatures of environmentally relevant exposures in normal human mammary epithelial cells: benzo[a]pyrene

Changes in gene expression in a panel of primary normal human mammary epithelial cell strains, developed from healthy breast tissue obtained at reduction mammoplasty from different donors, in response to benzo[a]pyrene exposure have been investigated. It was expected that both gene expression changes common to cell strains derived from different donors as well as inter-individual variation would be observed. Therefore, the strategy that has been adopted is to identify potentially important changes, or useful changes from a biomonitoring perspective, using gene-array technology and a small number of donors; then investigate selected transcription responses using a large number of tissue donors and a cheaper method of transcript detection (real-time polymerase chain reaction). Here we report results from four primary normal human mammary epithelial cell strains that were treated with benzo[a]pyrene in vitro for either 6 or 24 h. Transcription was monitored using high-density oligonucleotide arrays (Affymetrix HuGeneFL). Total RNA was used for the preparation of labeled targets that were hybridized to microarrays containing probes representing more than 6800 human genes and expressed sequence tags. Gene expression data were analyzed using the GeneChip software (MAS 5.0). Altered gene expression patterns were observed in response to benzo[a]pyrene in human mammary epithelial cell strains from different donors. Specifically, the dioxin inducible cytochrome P450 CYP1B1 was consistently induced in response to 6 and 24 h exposure to benzo[a]pyrene in cell strains from all four donors. Two other genes that were relatively consistently induced were IL1beta and MMP1. Less consistent changes in other metabolism genes (CYP1A1, CYP11B2, and NQO1) and certain cell cycle control genes GOS2 and AF1Q were also induced, while EGR1 was suppressed. Although no change in p53 transcription was observed, an accumulation of p53 protein was detected using antibodies. A similar accumulation of Waf1 (p21) was also observed using immunohistochemistry, this was expected since p53 is p21's transcription factor. Significant inter-individual variations in both the levels and patterns of gene expression were observed, in response to benzo[a]pyrene exposure. These studies provide a complementary approach to molecular epidemiology for the investigation of differential susceptibility to chemical carcinogens, and specifically polycyclic aromatic hydrocarbons.

Pesticide exposure and risk of breast cancer: a nested case-control study of residentially stable women living on Long Island

We conducted a nested case-control study of women in the New York State cohort who lived on Long Island. We estimated the historical environmental exposure to pesticides in 105 women diagnosed with breast cancer between 1980 and 1992 and 210 age and race-matched controls in this cohort of long-term residentially stable women who completed a short mailed questionnaire in 1980. Prior agricultural land use was assessed from aerial photographs taken in 1947 and 1950. Pesticides detected in drinking water were estimated from measures taken between 1977 and 1992. Geographic information system software was used to calculate the distance between residences and hazardous waste sites (HWS) containing pesticides. We found an increased breast cancer risk for women residing within 1 mile of HWS containing organochlorine pesticides (odds ratio [OR]=2.8; 95% confidence interval [CI], 1.1-7.1), after adjusting for other risk factors. A significant interaction was shown for women residing on land that was previously used for agriculture and women who were either nulliparous or had an older age at first birth (> or =26 yr old), compared to women who did not live on previously agricultural land and with a younger age (<26 yr old) at first birth (OR=6.4; 95%CI, 2.2-18.2). Study power was limited and confidence intervals were wide. Our findings suggest that exposure to pesticides in the environment needs to be more comprehensively investigated in relation to breast cancer risk.

Rat breast microsomal biotransformation of ethanol to acetaldehyde but not to free radicals: its potential role in the association between alcohol drinking and breast tumor promotion

We recently showed that mammary cytosolic xanthineoxidoreductase had the ability to bioactivate ethanol (EtOH) to acetaldehyde (AC) and free radicals. In the present study, we report that the microsomal fraction also biotransforms EtOH to AC. One pathway requires NADPH and the others do not. Both need oxygen. The NADPH-dependent pathway is not inhibited by CO:O(2) (80:20) or SKF 525A and that excludes the participation of cytochrome P450. It is inhibited by diethyldithiocarbamate (DDTC), sodium azide, and diphenyleneiodonium (DPI) but not by desferrioxamine, which suggests a possible role of a non-iron copper-requiring flavoenzyme. The process was partially inhibited by thiobenzamide (TBA), methylmercaptoimidazole (MMI), and nordihydroguaiaretic acid (NDG) but not by dapsone, aminotriazole, or indomethacin. These results suggest the potential participation of flavine monooxygenase and of lipooxygenase or of peroxidases/oxidases having similar characteristics but not of lactoperoxidase or cyclooxygenase. The pathway not requiring NADPH could also be partially inhibited by DDTC, NDG, azide, DPI, and TBA or MMI but not by the other chemicals. Little activity proceeds under nitrogen. Oxidases or peroxidases might be involved. No formation of 1-hydroxyethyl radicals was detected either in the presence or absence of NADPH. The nature of the EtOH bioactivating enzymes involved remains to be established. However, the fact remains that an activation of EtOH to AC was found in mammary tissue and could have a significant effect in some stages of the process of breast tumor promotion by EtOH.

Interaction of benzoquinone- and hydroquinone-derivatives of lower chlorinated biphenyls with DNA and nucleotides in vitro

Commercial polychlorinated biphenyls (PCBs) are complete carcinogens in rodents, however, their initiating (DNA damaging) activity has not been conclusively demonstrated. In the present study, we reacted synthetic 2-phenyl-1,4-benzoquinones (BQ) and 2-phenyl-1,4-hydroquinones (HQ) of 2-chloro-, 3-chloro-, 4-chloro-, 3,4-dichloro-, and 3,4,5-trichlorobiphenyls with calf thymus DNA and individual deoxynucleoside-3'-monophosphates for 4 h at 37 degrees C. Analysis of DNA adducts resulting from BQ and HQ derivatives of the test congeners by 32P-postlabeling showed essentially similar adduct patterns. However, the adduct pattern and reactivity differed with the congener used. Quantitatively, 2-chloro-BQ/HQ produced in the highest DNA adduct levels and 3,4,5-chloro-BQ/HQ was the least reactive. Chromatographic comparison of DNA and nucleotide adducts derived from 4-chloro-BQ revealed that cytosine, adenine, and thymidine in the DNA accounted for most of the DNA adducts. Interestingly, none of the adducts in DNA were guanine-derived, even though this mononucleotide was highly reactive. These results suggest that both BQ and HQ derivatives of PCBs are capable of covalently binding to DNA, and chromatographic similarity in adduct patterns resulting from these two metabolites suggest possible involvement of intermediary semiquinone radicals. Experiments are underway to determine their in vivo significance.

Environmental risk factors for breast cancer among African-American women

There are few unequivocably established environmental carcinogens for breast cancer in women. Nevertheless, environmental factors are believed to explain much of the international variation in breast cancer risk and possibly differences among racial/ethnic groups. Along with lifestyle, some adverse exposures may be higher in minority racial/ethnic groups and in underserved populations that experience higher ambient contamination. Associations have been found between environmental agents and breast cancer in subgroups of women who can be identified by common susceptibility traits as well as by timing of exposures at certain milestones of reproductive life. Susceptibility can be defined by social, environmental, and genetic modalities-factors that may predominate in certain racial/ethnic groups but that also transcend racial/ethnic boundaries. For example, genes involved in transcription and estrogen metabolism have rapid variants that are more prevalent among African-Americans, yet risk accompanying metabolic changes from these genes will prevail in all racial/ethnic groups. Lack of reliable exposure assessment remains a principal obstacle to elucidating the role of environmental exposures in breast cancer. Resources must be identified and consolidated that will enable scientists to improve exposure assessment and to assemble studies of sufficient size to address questions regarding exposure, susceptibility, and vulnerability factors in breast cancer. Breast cancer studies should be expanded to examine combinations of chemicals as well as competing or complementary exposures such as endogenous hormones, dietary intake, and behavioral factors.

Is exposure to endocrine disrupting compounds during fetal/post-natal development affecting the reproductive potential of farm animals?

Concerns have been raised about the potential adverse effects on reproductive health and immune status of farm animals following exposure to a range of natural and synthetic environmental compounds that disrupt normal hormonal actions. These compounds range from natural plant oestrogens (e.g. genistein, coumesterol) and mycoestrogens (e.g. Aflatoxins, zearalenone) to growth promoting pharmaceuticals (e.g. trenbolone acetate, melengastrol acetate) to chemicals spread in water, sewage sludge or the atmosphere such as detergents and surfactants (e.g. octylphenol, nonylphenol), plastics (e.g. bisphenol-A, phthalates), pesticides (e.g. methoxychlor, dieldrin, DDT) and industrial chemicals (e.g. PCB, TCDD). These compounds are commonly termed 'endocrine disrupting compounds' (EDCs) or 'endocrine disruptors' due to their ability to act as either hormone agonists or antagonists or the ability to disrupt hormone synthesis, storage or metabolism. A similar group of compounds are called 'immunotoxicants' and are thought to affect the immune system mainly by disrupting B and T cell homeostasis. As more studies are performed it is becoming clear that many compounds can directly or indirectly affect both the endocrine and immune systems. The susceptibility of target tissues is related to the stage of development, the cumulative exposure dose and the immune status of the individual. While some of the effects of the EDCs on the endocrine and immune systems are quite distinct, many are subtle and identifying the causative agent from the vast array of environmental challenges including EDCs, nutrition, temperature, etc. can be problematic. Identifying the causative agent is confounded by the possibility that effects that are observed in the adult may be due to exposure to EDCs during fetal life. This has major implications for the determination of universal end-point measurements to assess exposure to EDCs in farm animals.

An ecologic study of dietary and solar ultraviolet-B links to breast carcinoma mortality rates

BACKGROUND

The role of diet in the etiology of breast carcinoma has been debated for decades. The ecologic approach generally finds that dietary fat is highly associated with breast carcinoma mortality, with fish intake and solar ultraviolet-B (UV-B) radiation, a source of vitamin D, inversely associated. Case-control and cohort studies generally find a variety of chemical, nonfat dietary, environmental, genetic, lifestyle, and reproductive factors to be important.

METHODS

An ecologic study was conducted using breast carcinoma mortality rates (1989-1996), dietary supply data, and latitude (an index of solar UV-B radiation) from 35 countries.

RESULTS

The fraction of energy derived from animal products (risk) combined with that from vegetable products (risk reduction), followed by solar UV-B radiation and, to a lesser extent, energy derived from alcohol (risk) and fish intake (risk reduction), were found to explain 80% of the variance of breast carcinoma mortality rates. Dietary fat contributed insignificantly in regressions involving the other factors.

CONCLUSIONS

It is hypothesized that animal products are associated with risk for breast carcinoma because they are associated with greater amounts of insulin-like growth factor-1 and lifetime doses of estrogen. Vegetable products contain several risk reduction components including antioxidants and phytoestrogens. The association with latitude is very likely because of solar UV-B radiation and vitamin D. Alcohol modulates estrogen's effects on breasts. Fish intake is associated with risk reduction through vitamin D and n-3 oils. These results are consistent with those of many case-control and cohort studies but should be assessed in well designed cohort studies.

TP53 mutation patterns in breast cancers: searching for clues of environmental carcinogenesis

Mutations in the tumour suppressor gene TP53 occur in about 30% of breast cancers. We have used the IARC TP53 mutation database to analyse the pattern of mutations in breast cancers (1392 mutations). The global pattern of mutations is similar to the one of most other cancers, but there is an excess of transversions on G bases in tumours from Western (USA and Europe) as compared to Eastern (Japan) countries. Moreover, the patterns of inherited TP53 mutations associated with breast cancer, differ from those of somatic mutations. These differences support the hypothesis that a fraction of breast cancer mutations occur as a consequence of environmental exposures.

DDT environmental persistence from its use in a vector control program: a case study

DDT contamination was investigated in soil, sediment, and chicken eggs from an endemic leishmaniasis area located in Rio de Janeiro City, Brazil. The last DDT application in this area was in 1990, for sand-fly vector control. Sampling campaigns were conducted in 1997 and 1999. DDT was extracted by use of a modified soxhlet apparatus and analysis was performed by gas chromatography with electron capture detector. The results show that, in 1997, soil samples contained up to 351 microg x kg(-1) x d x w. of summation operator DDT near the insecticide-sprayed sites. In 1999, the soil concentration decreased to 112 microg x kg(-1) x d x w. of summation operator DDT. Sediments from small creeks also showed low concentrations (up to 32.9 microg x kg(-1) x d x w. of summation operator DDT). Chicken eggs had, on average, 1.98 mg x kg(-1) summation operator DDT (twice FAO's maximum residue limit), comprising 82% of p,p'-DDE. Taking into account the egg results, DDT bioaccumulation is a question of concern. Considering just the egg consumption, it was estimated that DDT intake in the study area is 0.38x10(-4) mg x kg(-1) body weight x day(-1) whereas the reference maximum dose (US EPA) is 5x10(-4) mg x kg(-1) body weight x day(-1). This approach can be used to estimate DDT exposure in other places where DDT contamination may be of concern, especially in places where locally produced animals and eggs are a significant portion of the diet.

Cytosolic xanthine oxidoreductase mediated bioactivation of ethanol to acetaldehyde and free radicals in rat breast tissue. Its potential role in alcohol-promoted mammary cancer

Epidemiological evidence links alcohol intake with increased risk in breast cancer. Not all the characteristics of the correlation can be explained in terms of changes in hormonal factors. In this work, we explore the possibility that alcohol were activated to acetaldehyde and free radicals in situ by xanthine dehydrogenase (XDh) and xanthine oxidase (XO) and/or aldehyde oxidase (AO). Incubation of cytosolic fraction with xanthine oxidoreductase (XDh+XO) (XOR) cosubstrates (e.g. NAD+, hypoxanthine, xanthine, caffeine, theobromine, theophylline or 1,7-dimethylxanthine) significantly enhanced the biotransformation of ethanol to acetaldehyde. The process was inhibited by allopurinol and not by pyrazole or benzoate or desferrioxamine and was not accompanied by detectable formation of 1HEt. However, hydroxylated aromatic derivatives of PBN were detected, suggesting either that hydroxyl free radicals might be formed or that XOR might catalyze aromatic hydroxylation of PBN. No bioactivation of ethanol to acetaldehyde was detectable when a cosubstrate of AO such as N-methylnicotinamide was included in cytosolic incubation mixtures. Results suggest that bioactivation of ethanol in situ to a carcinogen, such as acetaldehyde, and potentially to free radicals, might be involved in alcohol breast cancer induction. This might be the case, particularly also in cases of a high consumption of purine-rich food (e.g. meat) or beverages or soft drinks containing caffeine.

Organochlorine exposures and breast cancer risk in New York City women

A hospital-based case-control study of breast cancer risk related to organochlorine (OC) exposure was conducted in a multiethnic setting in New York City. We enrolled 175 breast cancer patients and 355 control patients. The overall racial/ethnic distribution was 57% Caucasian, 21% Hispanic, 22% African-American; cases and controls were frequency-matched by age and race/ethnicity. Tumor markers (estrogen and progesterone receptors, p53, erbB-2) were assessed and organochlorines (DDE, DDT, trans-nonachlor, and higher (HPCB) and lower (LPCB) chlorinated biphenyls) were measured in blood serum. Tumors among minority women were of slightly higher stage than among Caucasians, but tumor markers were similar across the racial/ethnic groups. DDE levels were highest among African-American and Hispanic women; DDT was highest among Hispanics; HPCBs were highest among African-Americans; LPCBs were lowest among Hispanics; and trans-nonachlor was highest among African-Americans. However, OC levels were not associated with risk for breast cancer, nor did OCs differ with respect to tumor stage or tumor markers. Higher DDE levels were associated with increasing body mass index (BMI), but with decreasing level of education, frequency of nulliparity, and frequency of family history of breast cancer. HPCB levels decreased with BMI and were not correlated with breast cancer risk factors. These relationships can be attributed to historical patterns of exposure and to metabolic differences in OCs related to BMI.

Prediction and assessment of the effects of mixtures of four xenoestrogens

The assessment of mixture effects of estrogenic agents is regarded as an issue of high priority by many governmental agencies and expert decision-making bodies all over the world. However, the few mixture studies published so far have suffered from conceptual and experimental problems and are considered to be inconclusive. Here, we report the results of assessments of two-, three- and four-component mixtures of o,p'-DDT, genistein, 4-nonylphenol, and 4-n-octylphenol, all compounds with well-documented estrogenic activity. Extensive concentration-response analyses with the single agents were carried out using a recombinant yeast screen (yeast estrogen screen, YES). Based on the activity of the single agents in the YES assay we calculated predictions of entire concentration-response curves for mixtures of our chosen test agents assuming additive combination effects. For this purpose we employed the models of concentration addition and independent action, both well-established models for the calculation of mixture effects. Experimental concentration-response analyses revealed good agreement between predicted and observed mixture effects in all cases. Our results show that the combined effect of o,p'-DDT, genistein, 4-nonylphenol, and 4-n-octylphenol in the YES assay does not deviate from expected additivity. We consider both reference models as useful tools for the assessment of combination effects of multiple mixtures of xenoestrogens.