Molecular epidemiology of breast cancer: genetic variation in steroid hormone metabolism

Trends and Age-Period-Cohort Effect on Incidence of Male Breast Cancer from 1980 to 2019 in Taiwan and the USA

Although male breast cancer (MBC) is globally rare, its incidence significantly increased from 1990 to 2017. The aim of this study was to examine variations in the trends of MBC incidence between populations in Taiwan and the USA from 1980 to 2019. The Taiwan Cancer Registry database and the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute of the USA were used. The age-standardized incidence rate was calculated using the world standard population in 2000. The long-term trends of the age, time period, and birth cohort effect on MBC incidence rates were estimated using the SEER Age-Period-Cohort Web Tool. The results revealed that the incidence of MBC in both countries increased from 2010 to 2019 (Taiwan: average annual percentage change (AAPC) = 2.59%; USA: AAPC = 0.64%). The age and period effects on the incidence rates in both countries strengthened, but the cohort effect was only identified in Taiwan (Rate ratio: 4.03). The identified cohort effect in this study bears resemblance to that noted in a previous investigation on female breast cancer in Taiwan. This suggests the possible presence of common environmental factors influencing breast cancer incidence in both genders, such as a high fat diet and xenoestrogen.

Nanomaterials for detection of biomolecules and delivering therapeutic agents in theragnosis: A review

Nanomaterials are emerging facts used to deliver therapeutic agents in living systems. Nanotechnology is used as a compliment by implementing different kinds of nanotechnological applications such as nano-porous structures, functionalized nanomaterials, quantum dots, carbon nanomaterials, and polymeric nanostructures. The applications are in the initial stage, which led to achieving several diagnoses and therapy in clinical practice. This review conveys the importance of nanomaterials in post-genomic employment, which includes the design of immunosensors, immune assays, and drug delivery. In this view, genomics is a molecular tool containing large databases that are useful in choosing an apt molecular inhibitor such as drug, ligand and antibody target in the drug delivery process. This study identifies the expression of genes and proteins in analysis and classification of diseases. Experimentally, the study analyses the design of a disease model. In particular, drug delivery is a boon area to treat cancer. The identified drugs enter different phase trails (Trails I, II, and III). The genomic information conveys more essential entities to the phase I trials and helps to move further for other trails such as trails-II and III. In such cases, the biomarkers play a crucial role by monitoring the unique pathological process. Genetic engineering with recombinant DNA techniques can be employed to develop genetically engineered disease models. Delivering drugs in a specific area is one of the challenging issues achieved using nanoparticles. Therefore, genomics is considered as a vast molecular tool to identify drugs in personalized medicine for cancer therapy.

Re-wiring and gene expression changes of AC025034.1 and ATP2B1 play complex roles in early-to-late breast cancer progression

Background

Elucidating the dynamic topological changes across different stages of breast cancer, called stage re-wiring, could lead to identifying key latent regulatory signatures involved in cancer progression. Such dynamic regulators and their functions are mostly unknown. Here, we reconstructed differential co-expression networks for four stages of breast cancer to assess the dynamic patterns of cancer progression. A new computational approach was applied to identify stage-specific subnetworks for each stage. Next, prognostic traits of genes and the efficiency of stage-related groups were evaluated and validated, using the Log-Rank test, SVM classifier, and sample clustering. Furthermore, by conducting the stepwise VIF-feature selection method, a Cox-PH model was developed to predict patients’ risk. Finally, the re-wiring network for prognostic signatures was reconstructed and assessed across stages to detect gain/loss, positive/negative interactions as well as rewired-hub nodes contributing to dynamic cancer progression.

Results

After having implemented our new approach, we could identify four stage-specific core biological pathways. We could also detect an essential non-coding RNA, AC025034.1, which is not the only antisense to ATP2B1 (cell proliferation regulator), but also revealed a statistically significant stage-descending pattern; Moreover, AC025034.1 revealed both a dynamic topological pattern across stages and prognostic trait. We also identified a high-performance Overall-Survival-Risk model, including 12 re-wired genes to predict patients’ risk (c-index = 0.89). Finally, breast cancer-specific prognostic biomarkers of LINC01612, AC092142.1, and AC008969.1 were identified.

Conclusions

In summary new scoring method highlighted stage-specific core pathways for early-to-late progressions. Moreover, detecting the significant re-wired hub nodes indicated stage-associated traits, which reflects the importance of such regulators from different perspectives.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12863-021-01015-9.

Anti-Angiogenic Treatments Interact with Steroid Secretion in Inflammatory Breast Cancer Triple Negative Cell Lines

Human inflammatory breast cancer (IBC) is a highly angiogenic disease for which antiangiogenic therapy has demonstrated only a modest response, and the reason for this remains unknown. Thus, the purpose of this study was to determine the influence of different antiangiogenic therapies on in vitro and in vivo steroid hormone and angiogenic growth factor production using canine and human inflammatory breast carcinoma cell lines as well as the possible involvement of sex steroid hormones in angiogenesis. IPC-366 and SUM149 cell lines and xenotransplanted mice were treated with different concentrations of VEGF, SU5416, bevacizumab and celecoxib. Steroid hormone (progesterone, dehydroepiandrostenedione, androstenedione, testosterone, dihydrotestosterone, estrone sulphate and 17β-oestradiol), angiogenic growth factors (VEGF-A, VEGF-C and VEGF-D) and IL-8 determinations in culture media, tumour homogenate and serum samples were assayed by EIA. In vitro, progesterone- and 17β-oestradiol-induced VEGF production promoting cell proliferation and androgens are involved in the formation of vascular-like structures. In vivo, intratumoural testosterone concentrations were augmented and possibly associated with decreased metastatic rates, whereas elevated E1SO4 concentrations could promote tumour progression after antiangiogenic therapies. In conclusion, sex steroid hormones could regulate the production of angiogenic factors. The intratumoural measurement of sex steroids and growth factors may be useful to develop preventive and individualized therapeutic strategies.

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.

Interaction between CYP1A1/CYP17A1 polymorphisms and parental risk factors in the risk of hypospadias in a Chinese population

Hypospadias (HS) is a common congenital malformation of the genitourinary tract in males and its etiology is viewed as multifactorial, and studies about gene-environment interaction in the etiology of HS are rare. A total of 152 cases and 151 controls were selected in the present study. Information before and during pregnancy from questionnaires finished by mothers of subjects were extracted, and the relating data were analyzed to determine the risk factors of HS. Meanwhile, maternal genomic DNA was genotyped for the single nucleotide polymorphisms (SNPs) of CYP1A1 rs1048943 and CYP17A1 rs4919686. Results of multivariable logistic regression analyses showed that several factors were associated with hypospadias risk. Analysis of the distributions of SNPs in CYP1A1 and CYP17A1 genes showed that the mutant genotype CC (OR = 4.87) of CYP1A1 rs1048943, and mutant genotype CC (OR = 5.82), recessive genotype AC + CC (OR = 2.17) and allele C (OR = 1.77) of CYP17A1 rs4919686 significantly increased the risk of HS. In addition, the additive gene-environment interactions were also found in several models. Several maternal risk factors that are associated with HS risk can interact with CYP1A1/CYP17A1 polymorphisms, which lead to infants vulnerable to occurrence of HS in Chinese populations.

CYP17 polymorphisms are associated with decreased risk of breast cancer in Chinese Han women: a case-control study

Introduction

CYP17 is the second most important enzyme in estradiol synthesis. Epidemiological studies have shown the associations between CYP17 polymorphisms and cancer risk. We conducted a case–control study to evaluate the relationship between CYP17 polymorphisms (rs743572 and rs2486758) and breast cancer (BC) risk.

Patients and methods

This case–control study included 560 BC patients and 583 age-matched healthy controls from Northwest China. Two polymorphisms (rs743572 and rs2486758) of CYP17 were genotyped by using Sequenom MassARRAY. ORs and 95% CIs were used to evaluate the relationship.

Results

Compared with the wild genotype of rs743572, we found a significantly reduced risk of BC associated with the variant genotypes (heterozygote model: OR=0.69, 95% CI=0.53–0.89; homozygote model: OR=0.68, 95% CI=0.49–0.95; dominant model: OR=0.69, 95% CI=0.54–0.87; overdominant model: OR=0.78, 95% CI=0.62–0.98; allele model: OR=0.79, 95% CI=0.66–0.93). For rs2486758 polymorphism, we did not find any difference in any of the genetic models. Further stratification analysis by clinical characteristics showed rs743572 was associated with estrogen receptor status (heterozygote model: OR=2.13, 95% CI=1.47–3.08; homozygote model: OR=3.29, 95% CI=1.94–5.58; dominant model: OR=2.39, 95% CI=1.69–3.37) and progesterone receptor status (homozygote model: OR=3.17, 95% CI=1.82–5.55), but there was no association between rs2486758 and clinical characteristics of BC. Haplotype analysis showed that G_rs743572C_rs2486758 haplotype was a protective factor of BC (OR=0.52, 95% CI=0.40–0.67). Survival analysis did not find that CYP17 rs743572 polymorphism was associated with triple-negative BC, either in terms of overall survival or progression-free survival.

Conclusion

Our results suggest that CYP17 polymorphisms may reduce the susceptibility to BC in Chinese women.

Association study of genetic variants in estrogen metabolic pathway genes and colorectal cancer risk and survival

Although studies have investigated the association of genetic variants and the abnormal expression of estrogen-related genes with colorectal cancer risk, the evidence remains inconsistent. We clarified the relationship of genetic variants in estrogen metabolic pathway genes with colorectal cancer risk and survival. A case-control study was performed to assess the association of single-nucleotide polymorphisms (SNPs) in ten candidate genes with colorectal cancer risk in a Chinese population. A logistic regression model and Cox regression model were used to calculate SNP effects on colorectal cancer susceptibility and survival, respectively. Expression quantitative trait loci (eQTL) analysis was conducted using the Genotype-Tissue Expression (GTEx) project dataset. The sequence kernel association test (SKAT) was used to perform gene-set analysis. Colorectal cancer risk and rs3760806 in SULT2B1 were significantly associated in both genders [male: OR = 1.38 (1.15-1.66); female: OR = 1.38 (1.13-1.68)]. Two SNPs in SULT1E1 were related to progression-free survival (PFS) [rs1238574: HR = 1.24 (1.02-1.50), P = 2.79 × 10^-2; rs3822172: HR = 1.30 (1.07-1.57), P = 8.44 × 10^-3] and overall survival (OS) [rs1238574: HR = 1.51 (1.16-1.97), P = 2.30 × 10^-3; rs3822172: HR = 1.53 (1.67-2.00), P = 2.03 × 10^-3]. Moreover, rs3760806 was an eQTL for SULT2B1 in colon samples (transverse: P = 3.6 × 10^-3; sigmoid: P = 1.0 × 10^-3). SULT2B1 expression was significantly higher in colorectal tumor tissues than in normal tissues in the Cancer Genome Atlas (TCGA) database (P < 1.0 × 10^-4). Our results indicated that SNPs in estrogen metabolic pathway genes confer colorectal cancer susceptibility and survival.

In vitro and in vivo effect of flutamide on steroid hormone secretion in canine and human inflammatory breast cancer cell lines

The aim was to study the effects of flutamide on cell proliferation, in vivo tumour growth and steroid production in canine and human IBC cell lines. IPC-366 and SUM149 cell cultures were exposed to flutamide concentrations for 72 hours. Additionally, IPC-366 and SUM149 xenotransplanted mice were treated subcutaneously with flutamide 3 times a week for 2 weeks. Steroid hormones determination in culture media, serum and tumour homogenates (pregnenolone, progesterone, androstenedione, testosterone, dihydrotestosterone, 17β-oestradiol and oestrone sulphate) were assayed by EIA. in vitro cell proliferation percentages showed a decrease in all flutamide dosages in IPC-366 and SUM149. in vivo flutamide reduced tumour size by 55% to 65%, and metastasis rates decreased. In treated groups, androgen levels in culture media, serum and tumour homogenates were increased as oestrogen levels decreased. These results suggest that flutamide treatment inhibits cell proliferation and promotes tumour reduction by increasing androgen levels and also support future therapy approaches.

The role of estradiol metabolism in urogenital schistosomiasis-induced bladder cancer

Urogenital schistosomiasis is a neglected tropical disease that can lead to bladder cancer. How urogenital schistosomiasis induces carcinogenesis remains unclear, although there is evidence that the human blood fluke Schistosoma haematobium, the infectious agent of urogenital schistosomiasis, releases estradiol-like metabolites. These kind of compounds have been implicated in other cancers. Aiming for enhanced understanding of the pathogenesis of the urogenital schistosomiasis-induced bladder cancer, here we review, interpret, and discuss findings of estradiol-like metabolites detected in both the parasite and in the human urine during urogenital schistosomiasis. Moreover, we predict pathways and enzymes that are involved in the production of these metabolites emphasizing their potential effects on the dysregulation of the tumor suppressor gene p53 expression during urogenital schistosomiasis. Enhanced understanding of these potential carcinogens may not only shed light on urogenital schistosomiasis-induced neoplasia of the bladder, but would also facilitate development of interventions and biomarkers for this and other infection-associated cancers at large.

Hydroxylation and sulfation of sex steroid hormones in inflammatory liver

Sex steroids, also known as gonadal steroids, are oxidized with hydroxylation by cytochrome P450, glucuronidation by UDP-glucuronosyltransferase, sulfation by sulfotransferase, andO-methylation by catechol O-methyltransferase. Thus, it is important to determine the process by which inflammation influences metabolism of gonadal hormones. Therefore, we investigated the mechanism of metabolic enzymes against high physiologic inflammatory responsein vivo to study their biochemical properties in liver diseases. In this study, C57BL/6N mice were induced with hepatic inflammation by diethylnitrosamine (DEN) exposure. We observed upregulation of Cyp19a1, Hsd17b1, Cyp1a1, Sult1e1 in the DEN-treated livers compared to the control-treated livers using real time PCR. Moreover, the increased Cyp19a1 and Hsd17b1 levels support the possibility that estrogen biosynthesis from androgens are accumulated during inflammatory liver diseases. Furthermore, the increased levels of Cyp1a1 and Cyp1b1 in the hydroxylation of estrogen facilitated the conversion of estrogen to 2- or 4-hydroxyestrogen, respectively. In addition, the substantial increase in the Sult1e1 enzyme levels could lead to sulfate conjugation of hydroxyestrogen. The present information supports the concept that inflammatory response can sequester sulfate conjugates from the endogenous steroid hormones and may suppress binding of sex steroid hormones to their receptors in the whole body.

Steroid Tumor Environment in Male and Female Mice Model of Canine and Human Inflammatory Breast Cancer

Canine inflammatory mammary cancer (IMC) shares clinical and histopathological characteristics with human inflammatory breast cancer (IBC) and has been proposed as a good model for studying the human disease. The aim of this study was to evaluate the capacity of female and male mice to reproduce IMC and IBC tumors and identify the hormonal tumor environment. To perform the study sixty 6–8-week-old male and female mice were inoculated subcutaneously with a suspension of 10⁶IPC-366 and SUM149 cells. Tumors and serum were collected and used for hormonal analysis. Results revealed that IPC-366 reproduced tumors in 90% of males inoculated after 2 weeks compared with 100% of females that reproduced tumor at the same time. SUM149 reproduced tumors in 40% of males instead of 80% of females that reproduced tumors after 4 weeks. Both cell lines produce distant metastasis in lungs being higher than the metastatic rates in females. EIA analysis revealed that male tumors had higher T and SO4E1 concentrations compared to female tumors. Serum steroid levels were lower than those found in tumors. In conclusion, IBC and IMC male mouse model is useful as a tool for IBC research and those circulating estrogens and intratumoral hormonal levels are crucial in the development and progression of tumors.

Genetic polymorphisms in estrogen-related genes and the risk of breast cancer among Han Chinese women

Exposure to high levels of estrogen is considered an important risk factor for susceptibility to breast cancer. Common polymorphisms in genes that affect estrogen levels may be associated with breast cancer risk, but no comprehensive study has been performed among Han Chinese women. In the present study, 32 single-nucleotide polymorphisms (SNPs) in estrogen-related genes were genotyped using the MassARRAY IPLEX platform in 1076 Han Chinese women. Genotypic and allelic frequencies were compared between case and control groups. Unconditional logistic regression was used to assess the effects of SNPs on breast cancer risk. Associations were also evaluated for breast cancer subtypes stratified by estrogen receptor (ER) and progesterone receptor (PR) status. Case-control analysis showed a significant relation between heterozygous genotypes of rs700519 and rs2069522 and breast cancer risk (OR = 0.723, 95% CI = 0.541-0.965, p = 0.028 and OR = 1.500, 95% CI = 1.078-2.087, p = 0.016, respectively). Subgroup comparisons revealed that rs2446405 and rs17268974 were related to ER status, and rs130021 was associated with PR status. Our findings suggest that rs700519 and rs2069522 are associated with susceptibility to breast cancer among the Han Chinese population and have a cumulative effect with three other identified SNPs. Further genetic and functional studies are needed to identify additional SNPs, and to elucidate the underlying molecular mechanisms.

Methods of integrating data to uncover genotype-phenotype interactions

Recent technological advances have expanded the breadth of available omic data, from whole-genome sequencing data, to extensive transcriptomic, methylomic and metabolomic data. A key goal of analyses of these data is the identification of effective models that predict phenotypic traits and outcomes, elucidating important biomarkers and generating important insights into the genetic underpinnings of the heritability of complex traits. There is still a need for powerful and advanced analysis strategies to fully harness the utility of these comprehensive high-throughput data, identifying true associations and reducing the number of false associations. In this Review, we explore the emerging approaches for data integration - including meta-dimensional and multi-staged analyses - which aim to deepen our understanding of the role of genetics and genomics in complex outcomes. With the use and further development of these approaches, an improved understanding of the relationship between genomic variation and human phenotypes may be revealed.

Review of genetic and environmental factors leading to hypospadias

Hypospadias is one of the most common congenital malformations, affecting about 4-6 males per 1000 male births, and ranging in severity from a urethral meatus that is slightly off-center to a meatus in the perineal area. Over the past three decades its prevalence may have increased due to changes in reporting of mild cases and/or increased survival of low birth weight infants due to improved neonatal care. However, despite the increasing numbers of males with hypospadias, the overall etiology remains unclear and likely multifactorial in nature. The purpose of this review article is to provide a comprehensive overview of the various factors implicated in hypospadias etiology, including genetic and environmental factors. In addition, we list syndromes in which hypospadias is a relatively common association and delineate the areas that require further investigation in an effort to understand this condition.

Polymorphisms in phase I and phase II genes and breast cancer risk and relations to persistent organic pollutant exposure: a case-control study in Inuit women

BACKGROUND

We have previously reported that chemicals belonging to the persistent organic pollutants (POPs) such as perfluorinated compounds (PFAS) and polychlorinated biphenyls (PCBs) are risk factors in Breast Cancer (BC) development in Greenlandic Inuit women. The present case-control study aimed to investigate the main effect of polymorphisms in genes involved in xenobiotic metabolism and estrogen biosynthesis, CYP1A1, CYP1B1, COMT and CYP17, CYP19 and the BRCA1 founder mutation in relation to BC risk and to explore possible interactions between the gene polymorphisms and serum POP levels on BC risk in Greenlandic Inuit women.

METHODS

The study population consisted of 31 BC cases and 115 matched controls, with information on serum levels of POPs. Genotyping was conducted for CYP1A1 (Ile462Val; rs1048943), CYP1B1 (Leu432Val; rs1056836), COMT (Val158Met; rs4680), CYP17A1 (A1> A2; rs743572); CYP19A1 (C> T; rs10046) and CYP19A1 ((TTTA)n repeats) polymorphisms and BRCA1 founder mutation using TaqMan allelic discrimination method and polymerase chain reaction based restriction fragment length polymorphism. The χ2 -test was used to compare categorical variables between cases and controls and the odds ratios were estimated by unconditional logistic regression models.

RESULTS

We found an independent association of CYP1A1 (Val) and CYP17 (A1) with BC risk.Furthermore, an increased BC risk was observed for women with high serum levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) and carriers of at least: one CYP1A1 variant Val allele; one variant COMT Met allele; or the common CYP17 A1 allele. No combined effects were seen between PFAS exposure and CYP1B1 and CYP19 polymorphisms. The risk of BC was not found significantly associated with exposure to PCBs and OCPs, regardless of genotype for all investigated SNPs. The frequency of the Greenlandic founder mutation in BRCA1 was as expected higher in cases than in controls.

CONCLUSIONS

The BRCA1 founder mutation and polymorphisms in CYP1A1 (Val) and CYP17 (A1) can increase the BC risk among Inuit women and the risk increases with higher serum levels of PFOS and PFOA. Serum PFAS levels were a consistent risk factor of BC, but inter-individual polymorphic differences might cause variations in sensitivity to the PFAS/POP exposure.

Adipose tissue PCB levels and CYP1B1 and COMT genotypes in relation to breast cancer risk in postmenopausal Danish women

Exposure to PCBs may be an etiologic factor for breast cancer. The cytochrome P450 1B1 (CYP1B1) and catechol-O-methyltransferase (COMT) enzymes are involved in estrogen metabolism and PCB metabolism, both of which may relate to breast cancer susceptibility. Polymorphisms in genes regulating these enzymes control efficiency. Our objective was to assess whether CYP1B1 and COMT gene polymorphisms modulate the effect of PCBs in breast cancer risk, among postmenopausal Danish women. Neither CYP1B1 Leu432Val polymorphisms nor adipose tissue PCBs were independently associated with breast cancer risk. When assessing the independent effect of the COMT Val158Met polymorphism, we observed reduced risk for breast cancer amongst hormone replacement therapy using women who were homozygous carriers of the variant allele compared with those carrying the wild-type variant (RR = 0.41; 95% CI: 0.29-0.89). We found no statistically significant interactions between any of the PCB groups and CYP1B1 or COMT polymorphisms on the risk of breast cancer.

The pharmacogenomics of sex hormone metabolism: breast cancer risk in menopausal hormone therapy

With women in western countries spending nearly one-third of their lifetime beyond menopause and a substantial number of these women facing severe menopausal symptoms, the goal of sex hormone pharmacogenomics is to promote the safe use of hormone replacement therapy (HRT). This could be achieved by providing molecular predictors for the upfront stratification of women in need of relief from menopausal symptoms into those with a likely benefit from HRT and those with a contraindication due to an HRT-associated breast cancer risk or other adverse effects. An increasing knowledge base of sex hormone metabolism and its variability, HRT outcomes and breast cancer susceptibility, as well as emerging examples of pharmacogenomic predictors, underscore the potential relevance of genetic variations for HRT outcome. The genes responsible for the metabolism, signaling and action of sex hormones are at the heart of this research; however, pharmacogenomic investigation of their therapeutic effects due to the enormous complexity of the biological pathways involved is still in its infancy. This article discusses the current knowledge, challenges and potential future directions towards the goal of genotype-guided safer HRT use.

Risk factors for breast cancer and expression of insulin-like growth factor-2 (IGF-2) in women with breast cancer in Wuhan City, China

Purpose

The purpose of this study was to explore the risk factors for breast cancer and establish the expression rate of IGF-2 in female patients.

Methods

A case control study with 500 people in case group and 500 people in control group. A self-administered questionnaire was used to investigate risk factors for breast cancer. All cases were interviewed during a household survey. Immune-histochemical method was used to inspect the expression of IGF-2 in different tissues (benign breast lesions, breast cancer and tumor-adjacent tissue).

Results

Multivariate adjusted odds ratios and 95% confidence intervals were calculated using unconditional logistic regression. High body mass index (OR = 1.012,95%CI = 1.008–1.016), working attributes (OR = 1.004, 95%CI = 1.002 = 1.006), long menstrual period (OR = 1.007, 95%CI = 1.005–1.009), high parity OR = 1.003, 95%CI = 1.001–1.005) , frequent artificial abortion (OR = 1.004, 95%CI = 1.001–1.005), family history of cancer (OR = 1.003, 95%CI = 1.000–1.005), period of night shift (OR = 1.003, 95%CI = 1.001–1.006), live in high risk environment (OR = 1.005, 95%CI = 1.002–1.008), and family problems (OR = 1.010, 95%CI = 1.005–1.014) were associated with increased risk for breast cancer. In this study, good sleeping status, positive coping strategies, subjective support, and utility degree of social support were associated with reduced risk for breast cancer (OR = 0.998, 0.997, 0.985, 0.998 respectively; 95%CI = 0.996–1.000, 0.994–1.000, 0.980–0.989, 0.996–1.000, respectively). In benign breast lesions, breast cancer and tumor-adjacent tissue, IGF-2 was mainly expressed in the cytoplasm, but its expression rate was different (p<0.05).

Conclusions

The incidence of breast cancer is a common result of multiple factors. IGF-2 is involved in the development of breast cancer, and its expression varies in different tissues (benign breast lesions, breast cancer and tumor-adjacent tissue).

Variability in estrogen-metabolizing genes and their association with genomic instability in untreated breast cancer patients and healthy women

In the present study, we investigated the relationship between polymorphisms in the estrogen-metabolizing genes CYP17, CYP1B1, CYP1A1, and COMT and genomic instability in the peripheral blood lymphocytes of 62 BC patients and 62 controls considering that increased or prolonged exposure to estrogen can damage the DNA molecule and increase the genomic instability process in breast tissue. Our data demonstrated increased genomic instability in BC patients and that individuals with higher frequencies of MN exhibited higher risk to BC when belonging Val/Met genotype of the COMT gene. We also observed that CYP17 and CYP1A1 polymorphisms can modify the risk to BC depending on the menopause status. We can conclude that the genetic background in estrogen metabolism pathway can modulate chromosome damage in healthy controls and patients and thereby influence the risk to BC. These findings suggest the importance to ally biomarkers of susceptibility and effects to estimate risk groups.

The association of polymorphisms in hormone metabolism pathway genes, menopausal hormone therapy, and breast cancer risk: a nested case-control study in the California Teachers Study cohort

Introduction

The female sex steroids estrogen and progesterone are important in breast cancer etiology. It therefore seems plausible that variation in genes involved in metabolism of these hormones may affect breast cancer risk, and that these associations may vary depending on menopausal status and use of hormone therapy.

Methods

We conducted a nested case-control study of breast cancer in the California Teachers Study cohort. We analyzed 317 tagging single nucleotide polymorphisms (SNPs) in 24 hormone pathway genes in 2746 non-Hispanic white women: 1351 cases and 1395 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by fitting conditional logistic regression models using all women or subgroups of women defined by menopausal status and hormone therapy use. P values were adjusted for multiple correlated tests (P_ACT).

Results

The strongest associations were observed for SNPs in SLCO1B1, a solute carrier organic anion transporter gene, which transports estradiol-17β-glucuronide and estrone-3-sulfate from the blood into hepatocytes. Ten of 38 tagging SNPs of SLCO1B1 showed significant associations with postmenopausal breast cancer risk; 5 SNPs (rs11045777, rs11045773, rs16923519, rs4149057, rs11045884) remained statistically significant after adjusting for multiple testing within this gene (P_ACT = 0.019-0.046). In postmenopausal women who were using combined estrogen-progestin therapy (EPT) at cohort enrollment, the OR of breast cancer was 2.31 (95% CI = 1.47-3.62) per minor allele of rs4149013 in SLCO1B1 (P = 0.0003; within-gene P_ACT = 0.002; overall P_ACT = 0.023). SNPs in other hormone pathway genes evaluated in this study were not associated with breast cancer risk in premenopausal or postmenopausal women.

Conclusions

We found evidence that genetic variation in SLCO1B1 is associated with breast cancer risk in postmenopausal women, particularly among those using EPT.

Genetic variability in estrogen disposition: Potential clinical implications for neuropsychiatric disorders

Variability in the physiological levels of neuroactive estrogens is widely believed to play a role in predisposition to several disorders of the central nervous system. Local biosynthesis of estrogens in the brain as well as their circulating serum levels are known to contribute to this pool of neuroactive steroids. It has been well accepted that estrogens modulate neuronal functions by affecting genesis, differentiation, excitability, and degeneration of nerve cells. These actions of estrogens appear to be more prominent in females with higher concentrations and marked variability of circulating serum levels occurring over a woman's lifetime. However, our knowledge regarding the variability of neuroactive steroid levels is very limited. Furthermore, several studies have recently reported differences in the synchronization of circulating and neuronal levels of estradiol. In the absence of reliable circulating steroid levels, knowledge of genetic variability in estrogen disposition may play a determining factor in predicting altered susceptibility or severity of neuropsychiatric disorders in women. Over the past decade, several genetic variants have been linked to both differential serum estrogen levels and predisposition to diverse types of neuropsychiatric disorders in women. Polymorphisms in genes encoding estrogen-metabolizing enzymes as well as estrogen receptors may account for this phenotypic variability. In this review, we attempt to show the contribution of genetics in determining estrogenicity in females with a particular emphasis on the central nervous system. This knowledge will further provide a driving force for unearthing the novel field of "Estrogen Pharmacogenomics." © 2010 Wiley-Liss, Inc.

DNA repair genes XRCC1 and XRCC3 polymorphisms and their relationship with the level of micronuclei in breast cancer patients

Breast cancer (BC) is the most prevalent type worldwide, besides being one of the most common causes of death among women. It has been suggested that sporadic BC is most likely caused by low-penetrance genes, including those involved in DNA repair mechanisms. Furthermore, the accumulation of DNA damage may contribute to breast carcinogenesis. In the present study, the relationship between two DNA repair genes, viz., XRCC1 (Arg399Gln) and XRCC3 (Thr241Met) polymorphisms, and the levels of chromosome damage detected in 65 untreated BC women and 85 healthy controls, was investigated. Chromosome damage was evaluated through micronucleus assaying, and genotypes determined by PCR-RFLP methodology. The results showed no alteration in the risk of BC and DNA damage brought about by either XRCC1 (Arg399Gln) or XRCC3 (Thr241Met) action in either of the two groups. Nevertheless, on evaluating BC risk in women presenting levels of chromosome damage above the mean, the XRCC3Thr241Met polymorphism was found to be more frequent in the BC group than in the control, thereby leading to the conclusion that there is a slight association between XRCC3 (241 C/T) genotypes and BC risk in the subgroups with higher levels of chromosome damage.

Factors influencing the association between CYP17 T34C polymorphism and the risk of breast cancer: meta-regression and subgroup analysis

A number of studies have been investigated the association between CYP17 T34C polymorphism and the risk of breast cancer; the results of these studies are inconsistent, however. This fact implies that the effect of CYP17 T34C polymorphism on susceptibility to breast cancer may be modified by other risk factors. In order to provide a more definitive conclusion, a full meta-analysis combining and summarizing 24 studies was first performed. Both traditional method and Bayesian approach were applied. Odds ratio was estimated using a dominant mode of inheritance after a biological justification for the choice of genetic model. The results of homogeneity analysis (H = 1.16, I (2) = 25.4%, and P = 0.127) suggested the presence of heterogeneity across the studies. Thus, random effects models simulated by the DerSimonian-Laird method were employed. The capability of a Bayesian approach was highlighted in the estimation of a pooled odds ratio and 95% confidence interval. The results of meta-analysis (OR = 1.001, CI = 0.832-1.208) suggest no significant association in the combined populations. Furthermore, Bayesian meta-regression and subgroup analysis were conducted to investigate the sources of heterogeneity. The risk factors evaluated in the study were menopausal status, ethnicity, age at menarche, age at first birth, parity, use of oral contraceptives, body mass index (BMI), and use of hormone repair therapy (HRT). After these population stratifications, there was evidence indicating that a possible impact of menopausal status, age at menarche, and BMI on the association between CYP17 T34C polymorphism and the risk of breast cancer.

Polymorphism of human cytochrome P450 enzymes and its clinical impact

Pharmacogenetics is the study of how interindividual variations in the DNA sequence of specific genes affect drug response. This article highlights current pharmacogenetic knowledge on important human drug-metabolizing cytochrome P450s (CYPs) to understand the large interindividual variability in drug clearance and responses in clinical practice. The human CYP superfamily contains 57 functional genes and 58 pseudogenes, with members of the 1, 2, and 3 families playing an important role in the metabolism of therapeutic drugs, other xenobiotics, and some endogenous compounds. Polymorphisms in the CYP family may have had the most impact on the fate of therapeutic drugs. CYP2D6, 2C19, and 2C9 polymorphisms account for the most frequent variations in phase I metabolism of drugs, since almost 80% of drugs in use today are metabolized by these enzymes. Approximately 5-14% of Caucasians, 0-5% Africans, and 0-1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant enzyme that demonstrates multiple genetic variants with a potentially functional impact on the efficacy and adverse effects of drugs that are mainly eliminated by this enzyme. Studies into the CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and *3 alleles. Extensive polymorphism also occurs in other CYP genes, such as CYP1A1, 2A6, 2A13, 2C8, 3A4, and 3A5. Since several of these CYPs (e.g., CYP1A1 and 1A2) play a role in the bioactivation of many procarcinogens, polymorphisms of these enzymes may contribute to the variable susceptibility to carcinogenesis. The distribution of the common variant alleles of CYP genes varies among different ethnic populations. Pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and currently available drugs. Further studies are warranted to explore the gene-dose, gene-concentration, and gene-response relationships for these important drug-metabolizing CYPs.

BRCA1-associated breast and ovarian cancer risks in Poland: no association with commonly studied polymorphisms

Polymorphisms in genes involved in DNA repair, steroid hormone biosynthesis/metabolism/signaling, folate metabolism as well as cell growth are prime candidates for possible associations with breast and ovarian cancer risk in women with an inherited predisposition. We investigated 29 polymorphisms in 20 genes encoding key proteins of the above four biological pathways for their breast and ovarian cancer risk modifying effect in Polish women harboring BRCA1 founder mutations. Of the analyzed genes, ERCC2, XRCC1, XRCC2, XRCC3 and Lig4 participate in DNA repair, TP53 in cell cycle check point control, AIB1, AR, COMT, CYP11A1, CYP17A1, CYP19A1, HSD17 and PGR in steroid hormone biosynthesis/metabolism/signaling, TYMS in folate metabolism and HER2, IL6, LRP1, TGFB and TGFBR1 affect cell growth. Using validated methods, we genotyped 319 breast cancer cases, 146 ovarian cancer cases and 290 unaffected controls, all of whom harbored one of three causative mutations in BRCA1. Our results revealed no association of any of the investigated polymorphisms with BRCA1-associated breast or ovarian cancer risk. Thus, it appears that these polymorphisms do not influence disease risk in Polish women carrying one of the three common BRCA1 founder mutations.

Increases in serum estrone sulfate level are associated with increased mammographic density during menopausal hormone therapy

BACKGROUND

Menopausal hormone therapy increases mammographic density. We determined whether increases in serum estrone sulfate (E(1)S) levels during menopausal hormone therapy predict increased mammographic density.

METHODS

We measured percent mammographic density and serum E(1)S levels in 428 participants of the Postmenopausal Estrogen/Progestin Interventions study who were randomly assigned to daily conjugated equine estrogen (CEE) 0.625 mg alone, CEE + daily medroxyprogesterone acetate (MPA) 2.5 mg, CEE + cyclical MPA (10 mg days 1-12 per 28-day cycle), or CEE + cyclical micronized progesterone (10 mg days 1-12). Serum E(1)S levels were determined by RIA. Information about covariates was determined by annual questionnaire. Using linear regression, we determined the association between change in E(1)S level from baseline to 12 months and change in percent mammographic density (by semiquantitative interactive threshold method).

RESULTS

After controlling for baseline mammographic density, age, body mass index, alcohol intake, parity, smoking, ethnicity, physical activity, and age at first pregnancy, mammographic density increased by 1.3% for every 1 ng/mL increase in E(1)S level (P < 0.0001). The association between change in E(1)S level and change in mammographic density differed by treatment group (greater effect in CEE + cyclical MPA group versus CEE group; P = 0.05). After controlling for treatment group, change in the ratio of E(1)S to E(1) was also positively associated with change in mammographic density.

CONCLUSIONS

Increases in serum E(1)S levels during menopausal hormone therapy are associated with increases in mammographic density. The relative contribution of E(1)S and E(1) to stimulation of breast tissue awaits further elucidation.

Do single nucleotide polymorphisms in xenobiotic metabolizing genes determine breast cancer susceptibility and treatment outcomes?

SNPs in CYP1A1, CYP2A1, CYP2B6, CYP2C, CYP2D6, CYP3A, GSTM1, GSTT1, GSTP1, SULT1A1, SULT1A2, UGT, and MTHFR are associated with breast cancer susceptibility; however, lack of such associations are also reported in some populations. The contradictory findings are explained on the basis of ethnic variation among populations and due to lack of proper sample size, detailed genotype-phenotype combinations and validation of gene expression studies at protein level. In this review, SNPs in these genes that have tremendous potential in identification of susceptible individuals, development of preventive strategies, treatment outcomes and their limitations are discussed.

Association of genetic polymorphisms in CYP19A1 and blood levels of sex hormones among postmenopausal Chinese women

OBJECTIVE

Circulating estrogen levels have been related to the risk of several female cancers. Blood levels of estrogen are controlled by estrogen synthesis enzymes. Genetic variation of estrogen genes thus may influence circulating estrogen levels. We investigated the associations of genetic polymorphisms in CYP19A1, a critical gene involved in estrogen synthesis, with plasma levels of sex hormones among postmenopausal Chinese women.

METHODS

Included in this study were 345 postmenopausal community controls from a population-based case-control study conducted in Shanghai. Fasting blood samples from those women were measured for blood estradiol, estrone, estrone sulfate, and testosterone. A total of 19 genetic polymorphisms in CYP19A1 were genotyped using ABI7900 or PCR-restriction fragment length polymorphism methods. Differences in plasma levels of hormones by genotype were examined using variance analysis.

RESULT

The geometric means of plasma levels of estradiol, estrone, estrone sulfate, and testosterone were 10.1, 16.8, 969.0, and 202.9 pg/ml, respectively, for this study population. We found that plasma levels of estrone were associated with rs28566535 (P=0.0180), rs730154 (P=0.0141), and rs936306 (P=0.0274) in block 2. In the same block, the haplotype CGCTA was related to level of estrone (P=0.0064). Single nucleotide polymorphism rs1902584 in block 1 was associated with estradiol only in overweight postmenopausal women. No clear association with sex hormones was noted for the other genetic polymorphisms evaluated in the study.

CONCLUSION

Single nucleotide polymorphisms in blocks 1 and 2 of the CYP19A1 gene are related to plasma levels of estrogen among postmenopausal Chinese women and may therefore play an important role in the etiology of hormone-related cancers.

Postmenopausal vaginal atrophy correlates with decreased estradiol and body mass index and does not depend on the time since menopause

OBJECTIVE

To evaluate the relationship between morphologic cell characteristics in Papanicolaou (Pap) smears and serum estradiol, body mass index (BMI) and the time elapsed since menopause. Study design. In 92 women Pap smears were grouped into atrophic and mature cell patterns and compared with estradiol, BMI and the time since menopause.

RESULTS

Forty-one patients with mature cell pattern were on average 7.1 years from menopause and 51 patients with atrophic pattern 8.2 years, but this difference was not significant. Estradiol in patients with mature cell pattern was significantly higher (52.1 +/- 48.5 pmol/l) than in patients with atrophic pattern (25.6 +/- 40.0 pmol/l). Similarly, BMI was significantly higher (27.9 +/- 4.2 kg/m(2)) in patients with mature cell pattern than in patients with atrophic pattern (25.7 +/- 3.8 kg/m(2)). There was no significant correlation between the time since menopause and estradiol among patients with mature and atrophic cell pattern. The same was true for the correlation between the time from menopause and BMI in patients with mature and atrophic pattern.

CONCLUSIONS

Estradiol and BMI are associated with vaginal cell maturation and atrophy in postmenopausal women. Vaginal cell atrophy does not depend on the time since menopause.

Defining targets for investigating the pharmacogenomics of adverse drug reactions to antifungal agents

Adverse drug reactions (ADRs) associated with antifungal therapy are major problems in patients with invasive fungal infections. Whether by clinical history or patterns of genetic variation, the identification of patients at risk for ADRs should result in improved outcomes while minimizing deleterious side effects. A major contributing factor to ADRs with antifungal agents relates to drug distribution, metabolism and excretion. Genetic variation in key genes can alter the structure and expression of genes and gene products (e.g., proteins). Thus far, the effort has focused on identifying polymorphisms with either empirical or predicted in silico functional consequences; the best candidate genes encode phase I and II drug-metabolizing enzymes (e.g., CYP2C19 and N-acetyltransferase), plasma proteins (albumin and lipoproteins) and drug transporters (P-glycoprotein and multidrug resistance proteins), which can affect the disposition of antifungal agents, eventually leading to dose-dependent (type A) toxicity. Less is known regarding the key genes that interact with antifungal agents, resulting in idiosyncratic (type B) ADRs. The possible role of certain gene products and genetic polymorphisms in the toxicities of antifungal agents are discussed in this review. The preliminary data address the following: low-density lipoproteins and cholesteryl ester transfer protein in amphotericin B renal toxicity; toll-like receptor 1 and 2 in amphotericin B infusion-related ADRs; phosphodiesterase 6 in voriconazole visual adverse events; flavin-containing monooxygenase, glutathione transferases and multidrug resistance proteins 1 and 2 in ketoconazole and terbinafine hepatotoxicity; CYP enzymes and P-glycoprotein in drug interactions between azoles and coadministered medications; multidrug resistance proteins 8 and 9 on 5-flucytosine bone marrow toxicity; and mast cell activation in caspofungin histamine release. This will focus on high-priority candidate genes, which could provide a starting point for molecular studies to elucidate the potential mechanisms for understanding toxicity associated with antifungal drugs as well as identifying candidate genes for large population prospective genetic association studies.

Estrogen-biosynthesis gene CYP17 and its interactions with reproductive, hormonal and lifestyle factors in breast cancer risk: results from the Long Island Breast Cancer Study Project

The genes that are involved in estrogen biosynthesis, cellular binding and metabolism may contribute to breast cancer susceptibility. We examined the effect of the CYP17 promoter T --> C polymorphism and its interactions with the reproductive history, exogenous hormone use and selected lifestyle risk factors on breast cancer risk among 1037 population-based incident cases and 1096 population-based controls in the Long Island Breast Cancer Study Project. Overall, there were no associations between the CYP17 genotype and breast cancer risk. Among postmenopausal women, the joint exposure to higher body mass index (BMI) and the variant C allele was associated with an increased risk of breast cancer [odds ratio (OR), 1.60; 95% confidence interval (CI), 1.15-2.22]. The joint exposure to the variant C allele and long-term use of hormone replacement therapy (HRT) (>51 months) was related to an increased risk of breast cancer (OR, 1.51; 95% CI, 0.99-2.31) especially estrogen receptor-positive, progesterone receptor-positive breast cancer (OR, 1.87; 95% CI, 1.08-3.25). Among the control population, the CYP17 variant C allele was inversely associated with long-term use of postmenopausal HRT and a higher BMI in postmenopausal women. In conclusion, the findings suggest that the CYP17 variant C allele may increase breast cancer risk in conjunction with long-term HRT use and high BMI in postmenopausal women.

Polymorphisms in the estrogen synthesis and metabolism pathways and symptoms during the menopausal transition: observations from the Seattle Midlife Women's Health Study

OBJECTIVE

The purpose of this study was to determine whether polymorphisms in the estrogen synthesis and metabolism pathways are associated with women's vasomotor symptom experiences during the menopausal transition.

DESIGN

In 2002, a subset of women enrolled in the Seattle Midlife Women's Health Study since 1990 (N = 174) provided a buccal smear for genotyping. Women were recruited by complete ascertainment of selected multiethnic neighborhoods in 1990. Participants were midlife women with a mean age of 53 years in 2005, well educated, employed, married, and represented a multiethnic population. Genotyping was done for the following polymorphisms: CYP1A1m2; CYP1B1*2 and CYP1B1*3; CYP17 5'UTR; CYP19 3'UTR; CYP19 (TTTA)n; including CYP19 7r and CYP19 7(r-3); CYP19 8r and CYP19 11r; and ESR1PvuII and ESR1XbaI. Women rated their vasomotor symptom severity in diaries on days 5, 6, and 7 of the menstrual cycle or on a constant date each month for women skipping periods. Menopausal transition stage was determined from daily menstrual calendars. First voided urine specimens provided several times each year were assayed for estrone glucuronide.

RESULTS

Women with the CYP19 11r polymorphism reported more severe and frequent hot flashes during the middle and late menopausal transition stages and postmenopause and higher E1G levels during middle and late stages. None of the other polymorphisms studied were related to hot flashes or to estrone glucuronide levels.

CONCLUSIONS

These findings suggest a possible role for CYP19 polymorphisms in estrogen levels and in vasomotor symptoms during the menopausal transition that warrants further study in larger and more diverse populations of women.

Influences on circulating oestrogens in postmenopausal women: relationship with breast cancer

Sex hormones are intrinsically linked to the development and treatment of the majority of breast cancers. High oestradiol levels are associated with elevated breast cancer risk in the postmenopausal setting and are given increasing importance in determining chemoprevention target groups. This review aims to evaluate the impact of various lifestyle factors including body mass index, diet, smoking, and alcohol on normal physiological sex hormone profiles. The role of genetic polymorphisms is also discussed, and all are placed within the context of designing future epidemiological studies and breast cancer risk algorithms.

Age-specific association of steroid hormone pathway gene polymorphisms with breast cancer risk

BACKGROUND

Breast cancer (BC) is a complex disease, and the incidence rates for BC increase with age. Both environmental factors and genetics have an impact on the risk of BC. Although the effects of environmental factors may vary with age, it has been assumed generally that the penetrance of single nucleotide polymorphisms (SNPs) is constant throughout life. In the current study, the results demonstrated that certain SNPs exhibit BC risk associations that vary considerably with age.

METHODS

SNPs in 12 steroid hormone pathway genes were investigated for associations with BC risk in white women who were enrolled in an age-matched, case-control (1:2 for cases and controls, respectively) study that consisted of a discovery set (n = 5000 women) and an independent validation set (n = 1583 women).

RESULTS

Significant age-related trends were identified and confirmed for SNPs in 4 genes associated with BC risk. The cytosine/cytosine (C/C) genotype of cytochrome P450 XIB2 (CYP11B2) was associated with decreased risk at younger ages (ages 30-44 years) but an increased risk at older ages (ages 55-69 years). The homozygous cytosine-guanine (CG/CG) genotype of uridine phosphorylase glycosyltransferase 1A7 (UGT1A7) was associated with increased risk at younger ages but decreased risk at older ages. Associations in cytochrome P450 19 (CYP19) and progesterone receptor (PGR) were confined to middle age (ages 45-54 years).

CONCLUSIONS

The identification of age-specific genetic associations may have profound implications for future etiologic studies of BC and for the use of SNP genotyping to accurately predict the risk of BC in women.

Expression of xenobiotic and steroid hormone metabolizing enzymes in human breast carcinomas

The potential to metabolize endogenous and exogenous substances may influence breast cancer development and tumor growth. Therefore, the authors investigated the protein expression of Glutathione S-transferase (GST) isoforms and cytochrome P450 (CYP) known to be involved in the metabolism of steroid hormones and endogenous as well as exogenous carcinogens in breast cancer tissue to obtain new information on their possible role in tumor progression. Expression of GST pi, mu, alpha and CYP1A1/2, 1A2, 3A4/5, 1B1, 2E1 was assessed by immunohistochemistry for primary breast carcinomas of 393 patients from the German GENICA breast cancer collection. The percentages of positive tumors were 50.1 and 44.5% for GST mu and CYP2E1, and ranged from 13 to 24.7% for CYP1A2, GST pi, CYP1A1/2, CYP3A4/5, CYP1B1. GST alpha was expressed in 1.8% of tumors. The authors observed the following associations between strong protein expression and histopathological characteristics: GST expression was associated with a better tumor differentiation (GST mu, p = 0.018) and with reduced lymph node metastasis (GST pi, p = 0.02). In addition, GST mu expression was associated with a positive estrogen receptor and progesterone receptor status (p < 0.001). CYP3A4/5 expression was associated with a positive nodal status (p = 0.018). Expression of CYP1B1 was associated with poor tumor differentiation (p = 0.049). Our results demonstrate that the majority of breast carcinomas expressed xenobiotic and drug metabolizing enzymes. They particularly suggest that GST mu and pi expression may indicate a better prognosis and that strong CYP3A4/5 and CYP1B1 expression may be key features of nonfavourable prognosis.

CYP19 (TTTA)n polymorphism and breast cancer risk in Brazilian women

A prolonged or increased exposure to endogenous estrogens associated with genetic factors are considered to be the main risk factors for breast cancer. The CYP19 gene encodes the enzyme aromatase, which catalyzes the conversion of androgens into estrogens. CYP19 alleles containing different numbers of tetranucleotide TTTA repeats in intron 4 have been associated with increased breast cancer risk. In this study we investigated, for the first time, the frequency of CYP19 (TTTA)n alleles in a South American population (n = 475) and analyzed the risk for developing breast cancer in a case-control study comprising 135 cases and 270 age-matched controls. It is shown that Brazilians possess not only the alleles identified in all the other populations studied so far (alleles containing from 7 to 13 TTTA repeats), but also the (TTTA)6 allele, that had never been described before. The (TTTA)10 allele was three times more frequent in cases when compared to controls and presented a significant positive association (p = 0.048) with breast cancer development in Brazilians.

Genotype distribution of estrogen receptor-alpha, catechol-O-methyltransferase, and cytochrome P450 17 gene polymorphisms in Caucasian women with uterine leiomyomas

OBJECTIVE

To evaluate the association between the presence of uterine leiomyomas and three functional single nucleotide polymorphisms (SNPs) of the estrogen receptor alpha (ESR1), catechol-O-methyltransferase (COMT), and cytochrom P450 17 (CYP17A) genes, which have been described to modify the estrogen metabolism.

DESIGN

Prospective case control study.

SETTING

Academic research institution.

PATIENT(S)

One hundred thirty women with clinically and surgically diagnosed uterine leiomyomas and 139 population controls.

INTERVENTION(S)

Peripheral venous puncture.

MAIN OUTCOME MEASURE(S)

Polymerase chain reaction and pyrosequencing were performed to genotype women with respect to the ESR1 IVS1-397 T/C (PvuII), COMT G158A, and the CYP17A 34T-->C SNPs.

RESULT(S)

Comparing women with uterine leiomyomas and controls, no statistically significant differences with respect to allele frequency and genotype distribution were ascertained for ESR1 IVS 1-397 T/C (PvuII) (P=0.9 and P=0.6, respectively), COMT G158A (P=0.3 and P=0.6, respectively), and CYP17A 34T-->C (P=0.1 and P=0.5, respectively). When all two-way interactions of investigated SNPs were ascertained, no significant interactions were observed. In a multivariate model, no SNP was significantly associated with leiomyomas.

CONCLUSION(S)

Carriage of the ESR1 IVS1-397 T/C (PvuII), COMT G158A, and the CYP17A 34T-->C SNPs is not associated with the susceptibility to uterine leiomyoma in a Caucasian population.

Interactive effects between CYP1A1 genotypes and environmental polychlorinated dibenzo-p-dioxins and dibenzofurans exposures on liver function profile

Previous studies reported that polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) induced hepatic cytochrome P-4501A1 (CYP1A1). The aim of this study was to examine the interactive influence of CYP1A1 genotypes and PCDD/Fs exposure on liver function profile. PCDD/Fs levels and liver function parameters were determined in serum and correlated with genetic polymorphism of CYP1A1/Msp 1 in 225 human volunteers who had no or minimal occupational exposure to PCDD/F. The results showed that the highest glutamate pyruvate transaminase (GPT) activity levels were found in subjects with homozygous variant CYP1A1/Msp 1, followed by heterozygous variant, and finally homozygous wild type for those individuals whose serum PCDD/Fs levels were higher than 17.4 pg WHO-TEQ/g lipid. Data suggest that GPT activity levels may be modified by interaction of CYP1A1/Msp 1 genotype with dioxin after adjustment for age, alcohol consumption, and history of liver illness. Further studies are needed to characterize the variation in other related genes to verify whether a correlation exists between serum PCDD/Fs levels and adverse health effects.

Multilocus analysis of SNP and metabolic data within a given pathway

BACKGROUND

Complex traits, which are under the influence of multiple and possibly interacting genes, have become a subject of new statistical methodological research. One of the greatest challenges facing human geneticists is the identification and characterization of susceptibility genes for common multifactorial diseases and their association to different quantitative phenotypic traits.

RESULTS

Two types of data from the same metabolic pathway were used in the analysis: categorical measurements of 18 SNPs; and quantitative measurements of plasma levels of several steroids and their precursors. Using the combinatorial partitioning method we tested various thresholds for each metabolic trait and each individual SNP locus. One SNP in CYP19, 3UTR, two SNPs in CYP1B1 (R48G and A119S) and one in CYP1A1 (T461N) were significantly differently distributed between the high and low level metabolic groups. The leave one out cross validation method showed that 6 SNPs in concert make 65% correct prediction of phenotype. Further we used pattern recognition, computing the p-value by Monte Carlo simulation to identify sets of SNPs and physiological characteristics such as age and weight that contribute to a given metabolic level. Since the SNPs detected by both methods reside either in the same gene (CYP1B1) or in 3 different genes in immediate vicinity on chromosome 15 (CYP19, CYP11 and CYP1A1) we investigated the possibility that they form intragenic and intergenic haplotypes, which may jointly account for a higher activity in the pathway. We identified such haplotypes associated with metabolic levels.

CONCLUSION

The methods reported here may enable to study multiple low-penetrance genetic factors that together determine various quantitative phenotypic traits. Our preliminary data suggest that several genes coding for proteins involved in a common pathway, that happen to be located on common chromosomal areas and may form intragenic haplotypes, together account for a higher activity of the whole pathway.

Screening for deleterious nonsynonymous single-nucleotide polymorphisms in genes involved in steroid hormone metabolism and response

To facilitate selection of single-nucleotide polymorphisms (SNP) for molecular epidemiologic studies investigating the hormonal carcinogenesis hypothesis, we used two sequence homology-based tools [Sort Intolerant from Tolerant (SIFT) and Polymorphism Phenotype (PolyPhen)] to predict the potential impact a nonsynonymous SNP (nsSNP), which results in an amino acid substitution, may have on the activity of proteins encoded by genes involved in the steroid hormone metabolism and response pathway. We screened 137 variants. Of these, 28% were predicted by SIFT and PolyPhen as having a potentially damaging effect on protein function. Investigation into the association of these variant alleles with hormone-related cancers may prove to be fruitful.

Role of Androgen Metabolism Genes CYP1B1, PSA/KLK3, and CYP11 in Prostate Cancer Risk and Aggressiveness

Candidate genes involved with androgen metabolism have been hypothesized to affect the risk of prostate cancer. To further investigate this, we evaluated the relationship between prostate cancer and multiple potentially functional polymorphisms in three genes involved in androgen metabolism: CYP1B1 (two single nucleotide polymorphisms: 355G/T and 4326C/G), prostate-specific antigen (PSA/KLK3 (three single nucleotide polymorphisms: -158A/G, -4643G/A, and -5412C/T), and CYP11alpha [(tttta)(n) repeat], using a moderately large (n = 918) sibling-based case-control population. When looking at all subjects combined, no association was observed between any polymorphism-or their haplotypes-and prostate cancer risk. However, among men with more aggressive prostate cancer, the CYP1B1 355G/T variant was positively associated with disease: carrying one or two T alleles gave odds ratios (OR) of 1.90 [95% confidence interval (95% CI), 1.09-3.31; P = 0.02] and 3.73 (95% CI, 1.39-10.0; P = 0.009), respectively. Similarly, carrying the CYP1B1 355T-4326C haplotype was positively associated with prostate cancer among men with high aggressive disease (P = 0.01). In addition, the PSA -158G/-158G genotype was positively associated with prostate cancer among men with less aggressive disease (OR, 2.71; 95% CI, 1.06-6.94; P = 0.04). Our findings suggest that CYP1B1 and PSA variants may affect the risk of prostate cancer and tumor aggressiveness.

Risk of Testicular Germ Cell Cancer in Relation to Variation in Maternal and Offspring Cytochrome P450 Genes Involved in Catechol Estrogen Metabolism

The incidence of testicular germ cell carcinoma (TGCC) is highest among men ages 20 to 44 years. Exposure to relatively high circulating maternal estrogen levels during pregnancy has long been suspected as being a risk factor for TGCC. Catechol (hydroxylated) estrogens have carcinogenic potential, thought to arise from reactive catechol intermediates with enhanced capability of forming mutation-inducing DNA adducts. Polymorphisms in maternal or offspring genes encoding estrogen-metabolizing enzymes may influence prenatal catechol estrogen levels and could therefore be biomarkers of TGCC risk. We conducted a population-based, case-parent triad study to evaluate TGCC risk in relation to maternal and/or offspring polymorphisms in CYP1A2, CYP1B1, CYP3A4, and CYP3A5. We identified 18- to 44-year-old men diagnosed with invasive TGCC from 1999 to 2004 through a population-based cancer registry in Washington State and recruited cases and their parents (110 case-parent triads, 50 case-parent dyads). Maternal or offspring carriage of CYP1A2 -163A was associated with reduced risk of TGCC [maternal heterozygote relative risk (RR), 0.6; 95% confidence interval (95% CI), 0.2-1.7; offspring heterozygote RR, 0.7; 95% CI, 0.3-1.5)]. Maternal CYP1B1 (48)Gly homozygosity was associated with a 2.7-fold increased risk of TGCC (95% CI, 0.9-7.9), with little evidence that Leu(432)Val or Asn(453)Ser genotypes were related to risk. Men were also at increased risk of TGCC if they carried the CYP3A4 -392G (RR, 7.0; 95% CI, 1.6-31) or CYP3A5 6986G (RR, 2.4; 95% CI, 1.1-5.6) alleles. These results support the hypothesis that maternal and/or offspring catechol estrogen activity may influence sons' risk of TGCC.

Cytochrome P450-mediated metabolism of estrogens and its regulation in human

Estrogens are eliminated from the body by metabolic conversion to estrogenically inactive metabolites that are excreted in the urine and/or feces. The first step in the metabolism of estrogens is the hydroxylation catalyzed by cytochrome P450 (CYP) enzymes. Since most CYP isoforms are abundantly expressed in liver, the metabolism of estrogens mainly occurs in the liver. A major metabolite of estradiol, 2-hydroxyestradiol, is mainly catalyzed by CYP1A2 and CYP3A4 in liver, and by CYP1A1 in extrahepatic tissues. However, CYP1B1 which is highly expressed in estrogen target tissues including mammary, ovary, and uterus, specifically catalyzes the 4-hydroxylation of estradiol. Since 4-hydroxyestradiol generates free radicals from the reductive-oxidative cycling with the corresponding semiquinone and quinone forms, which cause cellular damage, the specific and local formation of 4-hydroxyestradiol is important for breast and endometrial carcinogenesis. Changes in the expression level of estrogen-metabolizing CYP isoforms not only alter the intensity of the action of estrogen but may also alter the profile of its physiological effect in liver and target tissues. Generally, many CYP isoforms are induced by the substrates themselves, resulting in enhanced metabolism and elimination from the body. Of particular interest is a novel finding that human CYP1B1 is regulated by estradiol via the estrogen receptor. This fact suggests that the regulation of CYP enzymes involved in estrogen metabolism by estrogen itself would be physiologically significant for the homeostasis of estrogens at local organs. In this mini-review, we discuss the CYP-mediated metabolism of estrogens and the regulation of the estrogen-metabolizing CYP enzymes in relation to the risk of cancer.

Cytochrome P450 1B1 and catechol-O-methyltransferase genetic polymorphisms and breast cancer risk in Chinese women: results from the shanghai breast cancer study and a meta-analysis

Cytochrome P450 1B1 (CYP1B1) and catechol-O-methyltransferase (COMT) are important estrogen-metabolizing enzymes and, thus, genetic polymorphisms of these enzymes may affect breast cancer risk. A population-based case-control study was conducted to assess the association of breast cancer risk with CYP1B1 and COMT polymorphisms. A meta-analysis was done to summarize the findings from this and previous studies. Included in this study were 1,135 incident breast cancer cases diagnosed from August 1996 through March 1998 among female residents of Shanghai and 1,235 randomly selected, age frequency-matched controls from the same general population. The common alleles of the CYP1B1 gene were Arg (79.97%) in codon 48, Ala (80.53%) in codon 119, and Leu (86.57%) in codon 432. The Val allele accounted for 72.46% of the total alleles identified in codon 108/158 of the COMT gene. No overall associations of breast cancer risk were found with any of the single nucleotide polymorphisms described above. This finding was supported by a meta-analysis of all previous published studies. No gene-gene interactions were observed between CYP1B1 and COMT genotypes. The associations of breast cancer risk with factors related to endogenous estrogen exposure, such as years of menstruation and body mass index, were not significantly modified by the CYP1B1 and COMT genotypes. We observed, however, that women who carried one copy of the variant allele in CYP1B1 codons 48 or 119 were less likely to have estrogen receptor-positive breast cancer than those who carried two copies of the corresponding wild-type alleles. The results from this study were consistent with those from most previous studies, indicating no major associations of breast cancer risk with CYP1B1 and COMT polymorphisms.

Overexpression of Cytochrome P450 1A1 and Its Novel Spliced Variant in Ovarian Cancer Cells: Alternative Subcellular Enzyme Compartmentation May Contribute to Carcinogenesis

Epithelial ovarian cancer derived from the human ovarian surface epithelium (HOSE) is the leading cause of death from gynecologic malignancies among American women. Metabolic activation of endogenous and exogenous chemicals by cytochrome P450 (CYP) class I enzymes has been implicated in its etiology. In this study, we showed overexpression of CYP1A1 mRNA, but not CYP1B1 transcripts, in ovarian cancer cell lines when compared with primary cultures or immortalized HOSE cell lines. Importantly, we identified a novel, enzymatically active, spliced variant of CYP1A1 (CYP1A1v) formed by excision of an 84-bp cryptic intron in exon 2. CYP1A1v is overexpressed in ovarian cancer cell lines and exhibits a unique subcellular distribution restricted to the nucleus and mitochondria, contrary to the endoplasmic reticulum localization of the wild-type enzyme. In concordance, total CYP1A1 activity, as measured by the ethoxyresorufin O-deethylase assay, was detected in mitochondrial, nuclear, and microsomal fractions of ovarian cancer cells but was notably absent in all subcellular fractions of HOSE cells. Immunocytochemistry studies in 30 clinical specimens revealed overexpression of CYP1A1 in various types of ovarian cancers compared with benign epithelia and frequent localization of the enzyme to cancer cell nuclei. Forced expression of CYP1A1wt or CYP1A1v in HOSE cells resulted in nuclear localization of the enzyme and acquisition of anchorage-independent growth, which was further exacerbated following exposure to benzo(a)pyrene or 17beta-estradiol. Collectively, these data provided the first evidence that CYP1A1 overexpression and alternative splicing could contribute to ovarian cancer initiation and progression.