Association of repeat polymorphisms in the estrogen receptors alpha, beta (ESR1, ESR2) and androgen receptor (AR) genes with the occurrence of breast cancer

Androgen receptor (CAG)n repeat polymorphism contributes to risk of sudden cardiac death originated from coronary artery disease with sex discrepancy

Sudden cardiac death (SCD) is the leading cause of natural death worldwide which is responsible for almost half of all heart disease deaths, making it a substantial public health problem. Previous epidemiological studies from different countries have demonstrated the significant SCD incident difference rate between males and females. Besides environmental and social effects, differential genetic architecture also underlines the SCD incidence discrepancy. To this end, the functional (CAG)_n repeat polymorphism within Androgen Receptor (AR) gene was analyzed to evaluate its associations with SCD originated from coronary artery disease (SCD-CAD) susceptibility in Chinese populations using 182 SCD-CAD cases and 564 healthy controls. At allelic level, the (CAG)₂₆ allele conferred a lower SCD-CAD risk in males (adjusted odds ratio [OR] = 0.428; 95% confidence interval [CI] = 0.254, 0.915; P = 0.023). On the contrary, the (CAG)₂₆ allele was reversely associated with a higher SCD-CAD risk in females (OR = 2.581; 95% CI = 0.944, 7.056; P = 0.057). Further cutoff strategy analysis revealed that those male subjects carrying shorter allele (≤26 repeats) had significantly lower SCD-CAD risk (OR = 0.343; 95% CI = 0.221, 0.531; P = 8.1653e^-7). Additionally, an allele-dependent SCD risk tendency was observed in male subjects. Specifically, compared with males carrying allele longer than 26 repeats, the SCD-CAD risk (OR value) for male subjects carrying shorter alleles (from 25 to 21) gradually increased from 0.437 to 0.533, indicating the (CAG)₂₆ allele of the repeat polymorphism may be the watershed in male SCD etiology. Lastly, the length variations associated with multiple phenotypes were also summarized. Collectively, our results revealed for the first time that the (CAG)_n repeat polymorphism within the AR gene was associated with SCD-CAD risk in Chinese populations with sex discrepancy, proposing a new candidate genetic marker for molecular diagnosis of SCD-CAD. Furthermore, a sex-dependent SCD-CAD risk stratification and prevention approach was encouraged. Further studies with more female samples were warranted to validate our findings.

ESR2 gene variants (rs1256049, rs4986938, and rs1256030) and their association with breast cancer risk

Background

Variants of the estrogen receptor b (ESR2) gene have been associated with different types of cancer. However, these associations have been inconsistent. We genotyped the ESR2 variants (rs1256049, rs4986938, and rs1256030) in breast cancer (BC) patients and in healthy women.

Results

The variants rs1256049 and rs4986938 in the ESR2 gene were not associated with risk susceptibility in BC patients. However, the rs1256030 variant had an association as a risk factor for BC patients when compared with controls and BC patients for the TT genotype (odds ratio (OR) 1.86, 95% confidence intervals (CI) [1.05-3.28], p = 0.042). In addition, differences were observed in patients and controls carrying the TT genotype under 50 years of age (OR 1.85, 95% CI [1.05-3.27], p = 0.043). Thus, evident differences showed the rs1256030 variant in patients with TT, TC, and TC+TT genotypes with: (1) Stage IV (OR 1.60, 95% CI [1.06-2.54], p = 0.033), and (2) Luminal A (OR 1.60, 95% CI [0.47-0.21], p = 0.041), as well as in BC carriers of the TT genotype with indices of cellular proliferative (Ki-67) elevated (>20%) and overweight (OR 1.67, 95% CI [0.85-3.28], p = 0.041), respectively. In BC HER2 with lymph node metastasis, the TT genotype was a protective factor (OR 0.38, 95% CI [0.18-0.78], p = 0.005). The identification of haplotypes included two common GAT as risk factors (OR 3.1, 95% CI [1.31-7.72], p = 0.011) and GGC as a protective factor (OR 0.7, 95% CI [0.60-0.97], p = 0.034). The haplogenotype GGGATC was a risk factor (OR 2.5, 95% CI [1.28-5.0], p = 0.008).

Conclusion

The variant rs1256030 (TT) of the ESR2 gene and haplotype GAT were associated with susceptibility to BC as risk factors in this sample from the Mexican population.

Is the beta estradiol receptor receiving enough attention for its metabolic importance in postmenopause?

The relationship between menopause and the development of metabolic diseases is well established. In postmenopause women, there is an expansion of visceral white adipose tissue (WATv), which highly contributes to the rise of circulating lipids. Meanwhile, muscle glucose uptake decreases and hepatic glucose production increases. Consequently, in the pancreas, lipotoxicity and glycotoxicity lead to deficient insulin production. These factors initiate an energy imbalance and enhance the probability of developing cardiovascular and metabolic diseases. Although the activation of estradiol receptors (ER) has been shown to be beneficial for the WAT stock pattern, leading to the insulin-sensitive phenotype, authors have described the risk of these receptors' activation, contributing to neoplasia development. The selective activation of beta-type ER (ERβ) seems to be a promising strategy in the treatment of energy imbalance, acting on several tissues of metabolic importance and allowing an intervention with less risk for the development of estrogen-dependent neoplasia. However, the literature on the risks and benefits of selective ERβ activation still needs to increase. In this review, several aspects related to ERβ were considered, such as its physiological role in tissues of energy importance, beneficial effects, and risks of its stimulation during menopause. PubMed, SciELO, Cochrane, and Medline/Bireme databases were used in this study.

Evaluation of the epidemiological and prognosis significance of ESR2 rs3020450 polymorphism in ovarian cancer

AIM

To investigate the correlation between the polymorphism of estrogen receptor β gene (ESR2) rs3020450 and cancer susceptibility, and explore the epidemiological significance and the effect of ESR2 expression levels on the prognosis of ovarian cancer.

METHODS

Based on meta-analysis the association between ESR2 rs3020450 polymorphism and cancer susceptibility was estimated and a case-control design was used to verify this result in ovarian cancer. The epidemiological effect of ESR2 rs3020450 polymorphism was assessed by attributable risk percentage (ARP) and population attributable risk percentage (PARP). Kaplan Meier plotters were used to evaluate overall survival (OS) and progression-free survival (PFS) in ovarian cancer patients and GEPIA for the differential expression of ESR2 levels in ovarian cancer and adjacent normal tissues.

RESULTS

The pooled analysis indicated no significant correlation between the ESR2 rs3020450 polymorphism and the cancer susceptibility. In the stratified analysis by cancer types, significantly decreased risk was found in ovarian cancer (AG vs GG: OR = 0.73, 95%CI: 0.53-0.97, P = 0.03). Unconditional logistic regression results of case-control study in ovarian cancer observed significant differences in all comparisons (AG vs GG: OR = 0.81, 95%CI: 0.62-0.98, P = 0.04; AA vs GG: OR = 0.63, 95%CI: 0.42-0.92, P = 0.01 and AG + AA vs GG: OR = 0.73, 95%CI: 0.53-0.96, P < 0.001). Based on meta-analysis and case-control pooled results, ARP and PARP were evaluated respectively in allele (21.95% and7.97%), heterozygote (36.99% and 12.11%) and dominant model (36.84% and 12.97%) of rs3020450 polymorphism in ovarian cancer. The expression levels of ESR2 in normal tissues was significantly higher than that in cancer tissues (OV, Median, 4.7:0.21), and significant correlations were observed between high ESR2 expression levels and long OS (HR = 0.80, 95%CI: 0.70-0.92, P = 0.002) and PFS (HR = 0.767, 95%Cl: 0.67-0.88, P < 0.001).

CONCLUSION

Our results indicated that ESR2 rs3020450 polymorphism was associated with ovarian cancer risk from epidemiological perspective, and high ESR2 expression levels was associated with long survival in patients with ovarian cancer.

Neuroendocrine stress response is moderated by sex and sex hormone receptor polymorphisms

Sex hormones are significant regulators of stress reactivity, however, little is known about how genetic variation in hormone receptors contributes to this process. Here we report interactions between biological sex and repeat polymorphisms in genes encoding sex hormone receptors, and their effects on salivary cortisol reactivity in a sample of 100 participants (47 men & 53 women; 24.7 ± 3.23 years). Three genes were investigated: estrogen receptors alpha (ESR1) and beta (ESR2), and the androgen receptor (AR). Participants were classified as carrying 'Short' or 'Long' alleles based on median splits of the repeat distribution for each gene. Measures of physiological reactivity were collected before and after exposure to a canonical laboratory stressor and converted to traditional summary measures for analyses. Overall, men exhibited greater cortisol (p = 0.001) and mean arterial pressure reactivity (p = 0.002), while women displayed elevated heart rate throughout the session (p = 0.02). The effect of polymorphisms on salivary cortisol was sex sensitive. ESR1 was associated with differential reactivity in men (p = 0.04), but not women (p = 0.24). ESR2 genotype interacted with sex such that each additional 'Long' allele was associated with a 6.4% decrease in salivary cortisol in men, but a 9.5% increase in the levels of women (p = 0.02 for interaction). For the X-linked AR, the 'Long' allele was associated with decreased cortisol levels in men (p = 0.047), but in women had no effect (p = 0.75). Together, these results provide evidence for the saliency of genetic variation in sex hormone receptors on stress reactivity in humans and highlight their important role as mediators of hormonal activity.

Microsatellite variation of ESR1, ESR2, and AR in Serbian women with primary ovarian insufficiency

OBJECTIVE

This study aimed to investigate the potential role of microsatellite polymorphisms of the estrogen receptor alpha gene (ESR1) TA repeat, estrogen receptor beta gene (ESR2) CA repeat, and androgen receptor gene (AR) CAG and GGN repeats among Serbian women with primary ovarian insufficiency (POI). These microsatellites have been reported to be associated with POI in different racial/ethnic populations.

METHODS

A cohort of 196 POI cases matched with 544 fertile controls was recruited by the Institute for Endocrinology, Diabetes and Metabolic Disorders of Serbia between 2007 and 2010. DNA was extracted from saliva. The four microsatellites were genotyped using a PCR-based assay to determine the repeat lengths.

RESULTS

POI patients carried shorter repeat lengths of ESR2 (CA)_n than controls (P = 0.034), but the difference was small. ESR1 (TA)_n was on the borderline of statistical differences between groups (P = 0.059). AR (CAG)_n and (GGN)_n showed no association with POI.

CONCLUSIONS

We cautiously conclude that microsatellite polymorphisms of gonadal steroid receptor genes might contribute to the genetic basis of POI in Serbian women, but a larger-scale study and family-based studies are warranted to validate our findings even though the sample size in this study is larger than any previously published in this field.

Insight Analysis of Promiscuous Estrogen Receptor α-Ligand Binding by a Novel Machine Learning Scheme

Estrogen receptor α (ERα) plays a significant role in occurrence of breast cancer and may cause various adverse side-effects when ERα is an off-target protein. A theoretical model was derived to predict the binding affinity of ERα using the pharmacophore ensemble/support vector machine (PhE/SVM) scheme to consider the promiscuous characteristic of ERα. The estimations by PhE/SVM were discovered to be in good agreement with the observed values for those training molecules ( n = 31, r² = 0.80, q_CV² = 0.77, RMSE = 0.57, s = 0.58), test molecules ( n = 179, q² = 0.91-0.96, RMSE = 0.33, s = 0.26) and outliers ( n = 15, q² = 0.80-0.86, RMSE = 0.56, s = 0.49). When subjected to various statistical validations, the PhE/SVM model consistently fulfilled the strictest criteria. A mock test also asserted its predictivity. When compared with crystal structures, the calculated results are consistent with the reported ERα-ligand co-complex structure, and the plasticity nature of ERα is also disclosed. Consequently, this precise, fast, and robust model can be adopted to predict ERα-ligand binding affinities and to design safer non-ERα-targeted pharmaceuticals in the process of drug discovery and development.

Differential association of ESR1 and ESR2 gene variants with the risk of breast cancer and associated features: A case-control study

BACKGROUND

Estrogen is key to breast cancer pathogenesis, and acts by binding its receptor (ER), which exists as ERα and ERβ, encoded by ESR1 and ESR2 genes, respectively. Studies that investigated the association of ESR1 and ESR2 variants with breast cancer yielded mixed outcome, and ethnic contribution was proposed. We evaluated the association between ESR1 and ESR2 variants and breast cancer and associated features in Tunisian women.

METHODS

Retrospective case-control study involving 207 female breast cancer patients, and 284 control women. Genotyping was done by real-time PCR.

RESULTS

Minor allele frequencies (MAF) of tagging SNPs rs2234693 and rs3798577 (ESR1) were significantly higher, while MAF of rs1256049 (ESR2) was significantly lower in breast cancer patients vs.

CONTROLS

Patients carrying rs3798577 genotypes had higher risk, while rs1256049 genotype carriers had reduced risk of breast cancer. The association of ESR1 and ESR2 gene variants with breast cancer depended on ER and Her-2 status. ESR1 rs3798577 and ESR2 rs1256049 were associated with breast cancer in ER-positive cases, and ESR1 rs2234693, and rs3798577 were associated with breast cancer in Her-2-negative cases, while the association of ESR2 rs1256049 with breast cancer was seen in Her-2 positive cases. Haploview analysis identified 4-locus ESR1 haplotypes that were positively (CGTT, TACC, and TACT), and negatively (CGTC) associated with breast cancer. No ESR2 haplotypes associated with breast cancer were identified.

CONCLUSION

ESR1 alleles and genotypes, and specific 3-locus ESR1 haplotypes are related with increased breast cancer susceptibility in Tunisian women. However, ESR2 variant and specific 1-locus ESR1 haplotype have a protective effect.

Paternal Uniparental Disomy of Chromosome 14 with Hypospadias

Paternal uniparental disomy 14 (patUPD14) is a distinct, clinically recognizable syndrome. Using a clinical SNP microarray, we identified patUPD14 in a boy with a normal karyotype presenting cardiomyopathy and facial anomalies, a specific configuration of the thoracic ribs ('coat hanger sign'), and hypospadias. Analyses of polymorphic microsatellites confirmed the diagnosis of patUPD14. We discuss the functions of the genes included in the rearrangement and their involvement in the pathogenesis of these disorders, especially hypospadias. ESR2 single nucleotide polymorphisms (rs944050; 2681-4A>G) have been associated with an increased risk of hypospadias in previous studies. The patient's ESR2 (rs944050) genotype is GG, whereas the parents both exhibit an AG genotype. This report sheds light on the genetic phenomenon in which the combination of a polymorphism and UPD can lead to new phenotypes, such as hypospadias.

Androgen Receptor CAG Repeat Length and Estrogen Receptor Status in Postmenopausal Breast Cancer Prognosis

Purpose

The influence of the androgen receptor (AR) CAG repeat polymorphism on breast cancer is controversial. We investigated the combined effects of CAG repeat length and estrogen receptor (ER) status on prognosis in 355 postmenopausal women with primary breast cancer.

Methods

CAG repeat length was determined by the HUMARA test. Relapse-free survival (RFS) and overall survival (OS) according to the X-weighted CAG repeat biallelic mean (XWBM) were investigated by univariate and multivariate analysis.

Results

XWBM was not associated with RFS or OS, but a significant interaction between XWBM and ER status (p = 0.002) was found for OS. ER-negative patients with median XWBM <20 showed lower OS than ER-negative/XWBM ≥20 patients (HR = 0.270; 95% Cl: 0.073-0.999). ER-negative/XWBM <20 patients also had significantly lower OS than ER-positive women, irrespective of CAG repeat length (p<0.001). Accordingly, estimated OS was lowest in ER-negative patients with XWBM <20 (OS: 0.63, 95% CI: 0.41-0.79) and highest in ER-positive patients with XWBM <20 (OS: 0.95, 95% CI: 0.90-0.97).

Conclusions

Our data suggest that short CAG repeat length is associated with increased risk of death in ER-negative disease but is related to better survival when ER is expressed. These findings are in agreement with the hypothesis that AR may stimulate or inhibit breast cancer growth depending on ER status, AR transactivation, and the endocrine-metabolic environment of breast tumors. Evaluation of CAG repeat length together with ER status could help improve the estimation of the risk of death, with possible implications for the optimization of standard breast cancer treatment and implementation of prevention strategies.

CAG repeat polymorphisms in the androgen receptor and breast cancer risk in women: a meta-analysis of 17 studies

The association between polymorphic CAG repeats in the androgen receptor gene in women and breast cancer susceptibility has been studied extensively. However, the conclusions regarding this relationship remain conflicting. The purpose of this meta-analysis was to identify whether androgen receptor CAG repeat lengths were related to breast cancer susceptibility. The MEDLINE, PubMed, and EMBASE databases were searched through to December 2014 to identify eligible studies. Data and study quality were rigorously assessed by two investigators according to the Newcastle-Ottawa Quality Assessment Scale. The publication bias was assessed by the Begg’s test. Seventeen eligible studies were included in this meta-analysis. The overall analysis suggested no association between CAG polymorphisms and breast cancer risk (odds ratio [OR] 1.031, 95% confidence interval [CI] 0.855–1.245). However, in the subgroup analysis, we observed that long CAG repeats significantly increased the risk of breast cancer in the Caucasian population (OR 1.447, 95% CI 1.089–1.992). Additionally, the risk was significantly increased in Caucasian women carrying two alleles with CAG repeats ≥22 units compared with those with two shorter alleles (OR 1.315, 95% CI 1.014–1.707). These findings suggest that long CAG repeats increase the risk of breast cancer in Caucasian women. However, larger scale case-control studies are needed to validate our results.

Identification of a predictive biomarker for the beneficial effect of keishibukuryogan, a kampo (Japanese traditional) medicine, on patients with climacteric syndrome

Keishibukuryogan (KBG; Guizhi-Fuling-Wan in Chinese) is one of the Kampo (Japanese traditional) medicines used to treat patients with climacteric syndrome. KBG can be used by patients who cannot undergo hormone replacement therapy due to a history of breast cancer. We evaluated whether cytosine-adenine (CA) repeat polymorphism of the estrogen receptor β gene can be a predictor of the beneficial effect of KBG on climacteric syndrome. We also investigated the relationship between CA repeat polymorphism, the patients' profiles, and the therapeutic effect. We found that CA was an SS, SL, or LL genotype according to the number of repeats. We studied 39 consecutive patients with climacteric disorders who took KBG for 12 weeks. The diagnosis of climacteric disorders was made on the basis of the Kupperman index. KBG significantly improved the patients' climacteric symptoms (i.e., vasomotor symptoms in the patients with the LL genotype and melancholia in the patients with the SL genotype). No relationship between the patients' profiles and CA repeat polymorphism was recognized. CA repeat polymorphism could thus be a potential biomarker to predict the efficacy of KBG in climacteric syndrome, and its use will help to reduce the cost of treating this syndrome by focusing the administration of KBG on those most likely to benefit from it.

Menopausal status modifies breast cancer risk associated with ESR1 PvuII and XbaI polymorphisms in Asian women: a HuGE review and meta-analysis

BACKGROUND

Published data on the association between single nucleotide polymorphisms (SNPs) in the ESR1 gene and breast cancer susceptibility are inconclusive or controversial. The aim of this Human Genome Epidemiology (HuGE) review and meta-analysis was to derive a more precise estimation of this relationship.

METHODS

A literature search of Pubmed, Embase, Web of science and CBM databases was conducted from inception through September 1 th, 2012. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association.

RESULTS

A total of five studies including 1,678 breast cancer cases and 1,678 general population controls in Asian populations were involved in this meta-analysis. When all the eligible studies were pooled into the meta-analysis, the higher transcriptional activity variant allele T of ESR1 PvuII (C>T) (rs2234693) in pre-menopausal breast cancer women showed a significant relation to increased risk (OR = 1.13, 95%CI: 1.01-1.28, P = 0.040) in contrast to their post-menopausal counterparts which showed non-significant increased risk (OR = 1.01, 95%CI: 0.87-1.18, P = 0.858). Nevertheless, no significant association between ESR1 XbaI (A>G) (rs9340799) polymorphism and the risk of breast cancer was observed in pre-menopausal and post-menopausal individuals.

CONCLUSION

Based on a homogeneous Asian population, results from the current meta-analysis indicates that the ESR1 PvuII (C>T) polymorphism places pre-menopausal breast cancer women at risk for breast cancer, while ESR1 XbaI (A>G) polymorphism is not likely to predict the risk of breast cancer.

Genetic polymorphims of estrogen receptor alpha -397 PvuII (T>C) and -351 XbaI (A>G) in a portuguese population: prevalence and relation with breast cancer susceptibility

Estrogen receptor alpha (ERα), that mediates the biologic effects of estrogen in estrogen-sensitive tissues like breast, is genetically polymorphic. To evaluate the association between -397 PvuII (T>C) and -351 XbaI (A>G) restriction fragment length polymorphisms (RFLPs) in intron 1 of ERα gene and susceptibility of breast cancer, we undertook a case-control study in BRCA1 185delAG and 5382insC/BRCA2 6174delT negative Portuguese women. The study population consisted of 107 patients with histological diagnosis of breast cancer and 121 women with no history of breast cancer. Genomic DNA was extracted from blood samples and genotyping analyses were performed by PCR-RFLP. XbaI polymorphism was associated with a significant reduced risk of breast cancer for carriers of the x allele in homozygozity (OR 0.178; 95% CI 0.070-0.456; P<0.001) or heterozigozity (OR 0.223; 95% CI 0.089-0.561; P=0.001). The PvuII polymorphism was associated with a non-significantly reduced risk. The combined analysis of PvuII and XbaI polymorphisms revealed none synergistic effect of the two genotypes, except for simultaneous carriers of pp and xx genotypes, that have a reduced risk of breast cancer (OR 0.226; 95% CI 0.049-1.035; P=0.044). The combination of PvuII and XbaI genotypes into haplotypes showed that carriers of two copies of the px (ppxx) haplotype had a reduced risk of breast cancer (OR 0.405; 95% CI 0.194-0.843; P=0.014), compared with PX (PPXX+PPXx+PpXX+PpXx) haplotypes. PvuII and XbaI polymorphisms were in linkage disequilibrium both in cases (D=0.044, r2=0.049, X2=5.216, P=0.022) and controls (D=0.090, r2=0.139, X2=16.819, P<0.001), but not in the entire sample population analyzed as a whole (D=0.087, r2=0.0076, X2=1.733, P=0.188). In conclusion, in this case-control study we found that ERα gene XbaI polymorphism may modify individual susceptibility for breast cancer in this population.

Genetic variation in ESR2 and estrogen receptor-beta expression in lung tumors

OBJECTIVE

To investigate the association between inherited variation in the estrogen receptor beta (ERβ) gene (ESR2) and ERβ lung tumor expression, a phenotype that possibly affects survival differently in men and women.

METHODS

We genotyped 135 lung cancer patients for 22 ESR2 single nucleotide polymorphisms (SNPs) and measured nuclear and cytoplasmic ERβ expression by immunohistochemistry (IHC) in their primary lung tumor. Distributing Allred ERβ IHC scores according to ESR2 genotype classified under a dominant genetic model, we used rank sum tests to identify ESR2 SNPs significantly associated (p<0.05) with ERβ expression.

RESULTS

35%, 35%, and 29% of lung tumors showed no/low (Allred<6), intermediate (Allred 6-7), and maximal (Allred 8) cytoplasmic ERβ expression, whereas 13%, 27%, and 60% showed no/low, intermediate, and maximal nuclear ERβ expression. For SNPs rs8021944, rs1256061 and rs10146204, ERβ expression was higher according to the rank sum test in lung tumors from patients with at least one minor allele. For each of these three SNPs, the odds of maximal (Allred 8) relative to no/low (Allred<6) ERβ expression was 3-fold higher in tumors from patients with at least one minor allele than in tumors from patients homozygous for the common allele.

CONCLUSION

Inherited variability in ESR2 may determine ERβ lung tumor expression.

Eight functional polymorphisms in the estrogen receptor 1 gene and endometrial cancer risk: a meta-analysis

Background and Objective

Emerging evidence indicates that common functional polymorphisms in the estrogen receptor 1 (ESR1) gene may have an impact on an individual’s susceptibility to endometrial cancer, but individually published results are inconclusive. The aim of this meta-analysis is to derive a more precise estimation of the associations between eight polymorphisms in the ESR1 gene and endometrial cancer risk.

Methods

A literature search of PubMed, Embase, Web of Science and China Biology Medicine (CBM) databases was conducted on publications published before November 1^st, 2012. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Statistical analyses were performed using the STATA 12.0 software.

Results

Thirteen case-control studies were included with a total of 7,649 endometrial cancer cases and 16,855 healthy controls. When all the eligible studies were pooled into the meta-analysis, the results indicated that PvuII (C>T) polymorphism was associated with an increased risk of endometrial cancer, especially among Caucasian populations. There were also significant associations between rs3020314 (C>T) polymorphism and an increased risk of endometrial cancer. Furthermore, rs2234670 (S/L) polymorphism may decrease the risk of endometrial cancer. However, no statistically significant associations were found in XbaI (A>G), Codon 325 (C>G), Codon 243 (C>T), VNTR (S/L) and rs2046210 (G>A) polymorphisms.

Conclusion

The current meta-analysis suggests that PvuII (C>T) and rs3020314 (C>T) polymorphisms may be risk factors for endometrial cancer, especially among Caucasian populations.

Given breast cancer, is fat better than thin? Impact of the estrogen receptor beta gene polymorphisms

The role of estrogen receptor beta (ERβ) in breast cancer has been investigated since its identification in 1996. Studies based on protein expression have indicated that ERβ is a favorable prognostic marker. Further, ERβ expression is lower in obese breast cancer patients. Fewer studies have focused on the prognostic impact of ERβ polymorphisms. Therefore, we analyzed the associations between four previously identified haplotype tagging single nucleotide polymorphisms (htSNPs), associated haplo- and diplotypes, and breast cancer-free survival according to body constitution. The patient cohort included 634 women from the prospective breast cancer and blood study (BC Blood study, Sweden) with a median follow-up of 4.92 years. Four htSNPs (i.e., rs4986938, rs1256049, rs1256031, rs3020450) in the ESR2 gene and the correlating haplo- and diplotypes were analyzed and correlated to selected patient and tumor characteristics and to disease-free survival, including stratification for BMI. Based on the four htSNPs, seven haplotypes and eight diplotypes were identified. The patient and tumor characteristics were well-balanced across all geno- and haplotypes. Disease-free survival differed according to rs4986938 and rs1256031 (Log-Rank P = 0.045 and P = 0.041, respectively) and the number of haplotype copies of the wildtype CCGC and TCAC (Log-Rank P = 0.027 and P = 0.038, respectively). In the survival analyses stratified for BMI, significant survival differences between alleles were observed among overweight women (rs4986938 and rs1256031 with Log-Rank P = 0.001 and P = 0.001, respectively). The BMI-stratified survival analyses based on haplotypes showed shorter disease-free survival for overweight women with null copies of CCGC (Log-Rank P = 0.001) and for overweight women with any TCAC copy (Log-Rank P < 0.0001). Markedly impaired disease-free survival was found for genotypes in two out of four ESR2 htSNPs and for two haplotypes. ESR2 polymorphisms seem to divide patients into good and poor survivors based on BMI, stressing the need of taking host factors into consideration in the evaluation of prognostic markers.

The Rec protein of HERV-K(HML-2) upregulates androgen receptor activity by binding to the human small glutamine-rich tetratricopeptide repeat protein (hSGT)

The expression of endogenous retroviruses of the HERV-K(HML-2) family is strongly upregulated in germ cell tumors and several other cancers. Although the accessory Rec protein of HERV-K(HML-2) has been shown to induce carcinoma in situ in transgenic mice, to increase the activity of c-myc and to interact with the androgen receptor (AR), whether or not Rec expression is indeed implicated causally in the initiation or progression of any human malignancies remains unclear. We used the yeast two-hybrid system involving the Rec protein of a recently integrated HERV-K(HML-2) element in an effort to identify potential Rec-related oncogenic mechanisms. This revealed the human small glutamine-rich tetratricopeptide repeat (TPR)-containing protein (hSGT) to be a cellular binding partner. The interaction of Rec with this known negative regulator of the AR was confirmed by coimmunoprecipitation, pull-down assays and colocalization studies. The interaction involves the TPR motif of hSGT and takes place in the cytoplasm and in the nucleoli. Using an AR-responsive promoter and gene we could demonstrate that Rec interference with hSGT resulted in an up to five-fold increase in the activity of AR. Furthermore, in AR positive cells, Rec was shown to act as transactivator by enhancing AR-mediated activation of the HERV-K(HML-2) LTR promoter. This is in line with previous observations of elevated HERV-K(HML-2) expression in steroid-regulated tissues. On the basis of our findings we propose a "vicious cycle" model of Rec-driven hyperactivation of the AR leading to increased cell proliferation, inhibition of apoptosis and eventually to tumor induction or promotion.

Microsatellites in the estrogen receptor (ESR1, ESR2) and androgen receptor (AR) genes and breast cancer risk in African American and Nigerian women

Genetic variants in hormone receptor genes may be crucial predisposing factors for breast cancer, and microsatellites in the estrogen receptor (ESR1, ESR2) and androgen receptor (AR) genes have been suggested to play a role. We studied 258 African-American (AA) women with breast cancer and 259 hospital-based controls, as well as 349 Nigerian (NG) female breast cancer patients and 296 community controls. Three microsatellites, ESR1_TA, ESR2_CA and AR_CAG, in the ESR1, ESR2 and AR genes, respectively, were genotyped. Their repeat lengths were then analyzed as continuous and dichotomous variables. Analyses of continuous variables showed no association with breast cancer risk in either AA or NG at ESR1_TA; AA cases had shorter repeats in the long allele of ESR2_CA than AA controls (Mann-Whitney P= 0.036; logistic regression P = 0.04, OR= 0.91, 95% CI 0.83-1.00), whereas NG patients had longer repeats in the short allele than NG controls (Mann-Whitney P= 0.0018; logistic regression P= 0.04, OR= 1.06, 95% CI 1.00-1.11); and AA cases carried longer repeats in the short allele of AR_CAG than AA controls (Mann-Whitney P= 0.038; logistic regression P = 0.03, OR= 1.08, 95% CI 1.01-1.15). When allele sizes were categorized as dichotomous variables, we discovered that women with two long alleles of ESR2_CA had increased risk of breast cancer (OR = 1.38, 95% CI 1.10-1.74; P = 0.006). This is the first study to investigate these three microsatellites in hormonal receptor genes in relation to breast cancer risk in an indigenous African population. After adjusting for multiple-testing, our findings suggest that ESR2_CA is associated with breast cancer risk in Nigerian women, whereas ESR1_TA and AR_CAG seem to have no association with the disease among African American or Nigerian women.

Estrogen receptors and human disease: an update

A myriad of physiological processes in mammals are influenced by estrogens and the estrogen receptors (ERs), ERα and ERβ. As we reviewed previously, given the widespread role for estrogen in normal human physiology, it is not surprising that estrogen is implicated in the development or progression of a number of diseases. In this review, we are giving a 5-year update of the literature regarding the influence of estrogens on a number of human cancers (breast, ovarian, colorectal, prostate, and endometrial), endometriosis, fibroids, and cardiovascular disease. A large number of sophisticated experimental studies have provided insights into human disease, but for this review, the literature citations were limited to articles published after our previous review (Deroo and Korach in J Clin Invest 116(3):561-570, 2006) and will focus in most cases on human data and clinical trials. We will describe the influence in which estrogen's action, through one of or both of the ERs, mediates the aforementioned human disease states.

Estrogen receptor-Beta variants are associated with increased risk of Alzheimer's disease in women with down syndrome

BACKGROUND/AIMS

Genetic variants that affect estrogen activity may influence the risk of Alzheimer's disease (AD). We examined the relation of polymorphisms in the gene for the estrogen receptor-beta (ESR2) to the risk of AD in women with Down syndrome.

METHODS

Two hundred and forty-nine women with Down syndrome, 31-70 years of age and nondemented at baseline, were followed at 14- to 18-month intervals for 4 years. Women were genotyped for 13 single-nucleotide polymorphisms (SNPs) in the ESR2 gene, and their association with AD incidence was examined.

RESULTS

Among postmenopausal women, we found a 2-fold increase in the risk of AD for women carrying 1 or 2 copies of the minor allele at 3 SNPs in introns seven (rs17766755) and six (rs4365213 and rs12435857) and 1 SNP in intron eight (rs4986938) of ESR2.

CONCLUSION

These findings support a role for estrogen and its major brain receptors in modulating susceptibility to AD in women.

CAG repeat variants in the POLG1 gene encoding mtDNA polymerase-gamma and risk of breast cancer in African-American women

The DNA polymerase-gamma (POLG) gene, which encodes the catalytic subunit of enzyme responsible for directing mitochondrial DNA replication in humans, contains a polyglutamine tract encoded by CAG repeats of varying length. The length of the CAG repeat has been associated with the risk of testicular cancer, and other genomic variants that impact mitochondrial function have been linked to breast cancer risk in African-American (AA) women. We evaluated the potential role of germline POLG-CAG repeat variants in breast cancer risk in a sample of AA women (100 cases and 100 age-matched controls) who participated in the Women's Circle of Health Study, an ongoing multi-institutional, case-control study of breast cancer. Genotyping was done by fragment analysis in a blinded manner. Results from this small study suggest the possibility of an increased risk of breast cancer in women with minor CAG repeat variants of POLG, but no statistically significant differences in CAG repeat length were observed between cases and controls (multivariate-adjusted odds ratio 1.74; 95% CI, 0.49–6.21). Our study suggests that POLG-CAG repeat length is a potential risk factor for breast cancer that needs to be explored in larger population-based studies.

A systematic review of the relationship between polymorphic sites in the estrogen receptor-beta (ESR2) gene and breast cancer risk

The estrogen signal is mediated by the estrogen receptor (ER). The specific role of ER-beta, a second ER, in breast carcinogenesis is not known. A number of association studies have been carried out to investigate the relationship between polymorphic sites in the ESR2 gene and breast cancer risk, however, the results are inconsistent. We searched PubMed, Medline, and Web of Science database (updated to 10 January 2010) and identified 13 relevant case-control studies, and approximately 28 single-nucleotide polymorphisms (SNPs) and one micro-satellite marker were reported in the literature. The median number of study subjects was 776 (range 158-13,550). Three genetic variants [(CA)n, rs2987983, and rs4986938] showed significant overall associations with breast cancer, and rs4986938 was reported twice. Because rs4986938 and rs1256049 were the most extensively studied polymorphisms, we subsequently conducted a meta-analysis to evaluate their relationship with breast cancer risk (9 studies of 10,837 cases and 16,021 controls for rs4986938; 8 studies of 11,652 cases and 15,726 controls for rs1256049). For rs4986938, the women harboring variant allele seemed to be associated with a decreased risk either in the dominant model [pooled OR = 0.944, 95% confidence interval (95% CI) 0.897-0.993, fixed-effects] or in the co-dominant model (AG vs. GG) (OR = 0.944, 95% CI 0.895-0.997, fixed-effects). rs1256049 was not associated with breast cancer risk in any model. Five studies had investigated the effect of haplotypes in the ESR2 gene on breast cancer risk, and four of them had positive outcomes. In summary, the present systematic review suggests that SNP rs4986938 as well as haplotypes in the ESR2 gene might be associated with breast cancer. The need for additional studies examining these issues seems of vital importance.

Androgen receptor status predicts response to chemotherapy, not risk of breast cancer in Indian women

Background

Considerably little is known about the biological role and clinical significance of androgen receptor expression in breast cancer. The objectives of this study were to characterize AR-CAG repeat genotypes in a cohort of women with breast cancer and to determine the influence of AR on response to neoadjuvant chemotherapy and clinical outcome.

Materials and methods

Genotyping of the AR CAG repeat region was done on 70 patients and 80 healthy aged- matched female controls. To assess response to NACT, tissue samples from 30 LABC cases were evaluated quantitatively by real time for AR mRNA expression. The clinical response was correlated with both the pre and post chemotherapy AR expression. The CAG alleles did not show differences between cases and controls when the mean of short, long and average length of both CAG alleles was considered. However, analysis when done defining short allele as CAGn < 20 (AR1) and the long as CAGn ≥ 20 (AR2), risk was found associated with AR2 allele with marginal significance (P = 0.09). Stratification by age of onset, FH, stage, grade ER and AR status failed to reveal any association with breast cancer risk. Genotype carriers with ≥20 CAGn showed decrease of AR mRNA expression although significance could not be established (P = 0.47). Tumours in responders had the higher AR mRNA expression levels in pre neo-adjuvant chemotherapy condition (p < 0.02) which got reduced after neoadjuvant chemotherapy and the difference was found to be significant (P = 0.014).

Conclusions

Although, expansion of the CAGn in the AR gene doesn't show any major effect on breast cancer risk, patients with positive AR expression, pre neoadjuvant chemotherapy, were found to be good responders and a decrease in mRNA level of AR gene related to the chemotherapy-induced apoptosis could serve as an important independent predictor of response to NACT.

Mutations in mitochondrial DNA polymerase-gamma promote breast tumorigenesis

Decreased mitochondrial oxidative phosphorylation (OXPHOS) is one of the hallmarks of cancer. To date, the identity of nuclear gene(s) responsible for decreased OXPHOS in tumors remains unknown. It is also unclear whether mutations in nuclear gene(s) responsible for decreased OXPHOS affect tumorigenesis. Polymerase-gamma (POLG) is the only DNA polymerase known to function in human mitochondria. Mutations in POLG are known to cause mitochondrial DNA (mtDNA) depletion and decreased OXPHOS, resulting in mtDNA depletion syndrome in humans. We therefore sequenced all coding exons (2-23) and flanking intron/splice junctions of POLG in breast tumors. We found that the POLG gene was mutated in 63% of breast tumors. We identified a total of 17 mutations across the POLG gene. Mutations were found in all three domains of the POLG protein, including T251I (the exonuclease domain), P587L (the linker region) and E1143G (the polymerase domain). We identified two novel mutations that include one silent (A703A) and one missense (R628Q) mutation in the evolutionarily conserved POLG linker region. In addition, we identified three novel mutations in the intronic region. Our study also revealed that mtDNA was depleted in breast tumors. Consistently, mutant POLG, when expressed in breast cancer cells, induced a depletion of mtDNA, decreased mitochondrial activity, decreased mitochondrial membrane potential, increased levels of reactive oxygen species and increased Matrigel invasion. Together, our study provides the first comprehensive analysis of the POLG gene mutation in human cancer and suggests a function for POLG (1) in decreased OXPHOS in cancers and (2) in promoting tumorigenicity.

Single nucleotide polymorphisms within the estrogen receptor beta gene are linked with reproductive indices in Japanese flounder, Paralichthys olivaceus

The objectives of this study were to characterize polymorphisms within the coding region of estrogen receptor beta (ERbeta) gene in a population of 57 female Japanese flounder (Paralichthys olivaceus) and to analyze the association of ERbeta polymorphisms with reproductive indices by polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP). Two single nucleotide polymorphisms (SNPs), SNP1 (c.577delC) and SNP2 [c.A891T (p.Gln114Leu)], were identified in the ERbeta gene. A one-way ANOVA revealed that SNP1 was significantly associated with the gonadosomatic index (GSI) in female Japanese flounder (P < 0.05). And SNP2 was significantly associated with the serum 17beta-estradiol (E2) level and GSI (P < 0.05). Individuals with genotype AB of SNP2 had significantly higher serum E2 level and GSI than those of genotype AA (P < 0.05). Moreover, the hepatosomatic index (HSI), a marker for genetic effects, was significantly higher for diplotype D2 compared with the other three diplotypes (P < 0.05). These results obtained in this study suggested that SNP2 could influence reproductive endocrinology of female Japanese flounder and be useful as a potential candidate genetic marker for the selection of reproductive indices in female Japanese flounder.