Variants in estrogen metabolism and biosynthesis genes and urinary estrogen metabolites in women with a family history of breast cancer

Optimization and validation of a GC-MS quantitative method for the determination of an extended estrogenic profile in human urine: Variability intervals in a population of healthy women

An analytical method based on GC-MS was developed for the determination of a wide panel of urinary estrogens, together with their principal metabolites. Because of the low concentration of estrogens in urine, an efficient sample pre-treatment was optimized by a design of experiment (DoE) procedure to achieve satisfactory sensitivity. A second DoE was built for the optimization of the chromatographic run, with the purpose of reaching the most efficient separation of analytes with potentially interfering ions and similar chromatographic properties. The method was fully validated using a rigorous calibration strategy: from several replicate analyses of blank urine samples spiked with the analytes, calibration models were built with particular attention to the study of heteroscedasticity and quadraticity. Other validation parameters, including the limit of detection, intra-assay precision and accuracy, repeatability, selectivity, specificity, and carry-over, were obtained using the same set of data. Further experiments were performed to evaluate matrix effect and extraction recovery. Then the urinary estrogen profiles of 138 post-menopausal healthy women were determined. These profiles provide a representation of physiological concentration ranges, which, in forthcoming studies, will be matched on the base of multivariate statistics with the urinary estrogenic profile of women with breast or ovarian cancer.

Disturbed testicular expression of the estrogen-metabolizing enzymes CYP1A1 and COMT in infertile men with primary spermatogenic failure: possible negative implications on Sertoli cells

Estradiol (E₂ ) is normally metabolized to hydroxyestradiols and methoxyestradiols by CYP1A1, CYP1B1 and COMT. However, an altered production of these metabolites by a disturbed expression of these enzymes is associated with reproductive and non-reproductive pathologies. In vitro studies suggest that increased hydroxyestradiols and methoxyestradiols intratesticular generation is related to male infertility, but no studies have explored whether infertile men have a disturbed testicular expression of the enzymes that generate these E₂ metabolites. The aim of this study was to assess CYP1A1, CYP1B1 and COMT testicular expression at mRNA and protein level in men with spermatogenic impairment. Seventeen men with primary spermatogenic failure (13 with Sertoli cell-only syndrome and four with maturation arrest) and nine controls with normal spermatogenesis were subjected to testicular biopsy. mRNA was quantified using real-time RT-PCR and protein expression was evaluated using western blot and immunohistochemistry followed by integrated optic density analysis. Besides, the effects of hydroxyestradiols and methoxyestradiols on testosterone-induced transcriptional activity were evaluated in TM4 cells using a luciferase reporter assay system. Our results show that patients with Sertoli cell-only syndrome had significantly elevated COMT expression at the mRNA level, higher COMT immunoreactivity in their seminiferous tubules and increased protein expression of the soluble COMT isoform (S-COMT), whereas patients with maturation arrest had significantly elevated CYP1A1 mRNA levels and higher CYP1A1 immunoreactivity in interstitial space. Finally, 2-hydroxyestradiol decreased testosterone-induced transcriptional activity in Sertoli cells in vitro. In conclusion, male infertility is related to disturbed testicular expression of the enzymes responsible for producing hydroxyestradiols and/or methoxyestradiols. If these changes are related with increased intratesticular hydroxyestradiols and methoxyestradiols concentrations, they could elicit an impaired Sertoli cell function. Our results suggest CYP1A1 and COMT as new potential targets in treating male infertility.

Progress in solving the sex hormone paradox in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a devastating and progressive disease with marked morbidity and mortality. Even though being female represents one of the most powerful risk factors for PAH, multiple questions about the underlying mechanisms remain, and two "estrogen paradoxes" in PAH exist. First, it is puzzling why estrogens have been found to be protective in various animal models of PAH, whereas PAH registries uniformly demonstrate a female susceptibility to the disease. Second, despite the pronounced tendency for the disease to develop in women, female PAH patients exhibit better survival than men. Recent mechanistic studies in classical and in novel animal models of PAH, as well as recent studies in PAH patients, have significantly advanced the field. In particular, it is now accepted that estrogen metabolism and receptor signaling, as well as estrogen interactions with key pathways in PAH development, appear to be potent disease modifiers. A better understanding of these interactions may lead to novel PAH therapies. It is the purpose of this review to 1) review sex hormone synthesis, metabolism, and receptor physiology; 2) assess the context in which sex hormones affect PAH pathogenesis; 3) provide a potential explanation for the observed estrogen paradoxes and gender differences in PAH; and 4) identify knowledge gaps and future research opportunities. Because the majority of published studies investigated 17β-estradiol and/or its metabolites, this review will primarily focus on pulmonary vascular and right ventricular effects of estrogens. Data for other sex hormones will be discussed very briefly.

Polymorphisms in the promoter region of estrogen receptor β gene in endometrial cancer

INTRODUCTION

The development of endometrial cancer is known to be affected by estrogens. Thus, genetic variations like single nucleotide polymorphisms (SNPs) in genes involved in estrogen biosynthesis, metabolism, and signal transduction might affect risk for endometrial cancer. In this study, we tested the hypothesis that polymorphisms in the promoter of ESR2 gene may be associated with susceptibility to this disease.

METHODS

We compared the frequency of three SNPs in the promoter region of ESR2 gene (rs2987983, rs3020450, and rs3020449) in 135 women with endometrial cancer and 135 healthy women serving as controls by means of allele-specific tetra-primer PCR.

RESULTS

Regarding allele frequency, allele positivity or genotype frequencies of these SNPs we did not observe any significant difference between healthy women and women with endometrial cancer.

CONCLUSION

Our data clearly suggest that the tested SNPs in the promotor region of human ESR2 gene are not associated with the development of endometrial cancer.

Gender, sex hormones and pulmonary hypertension

Most subtypes of pulmonary arterial hypertension (PAH) are characterized by a greater susceptibility to disease among females, although females with PAH appear to live longer after diagnosis. While this "estrogen paradoxȍ of enhanced female survival despite increased female susceptibility remains a mystery, recent progress has begun to shed light upon the interplay of sex hormones, the pathogenesis of pulmonary hypertension, and the right ventricular response to stress. For example, emerging data in humans and experimental models suggest that estrogens or differential sex hormone metabolism may modify disease risk among susceptible subjects, and that estrogens may interact with additional local factors such as serotonin to enhance the potentially damaging chronic effects of estrogens on the pulmonary vasculature. Regardless, it remains unclear why not all estrogenic compounds behave equally, nor why estrogens appear to be protective in certain settings but detrimental in others. The contribution of androgens and other compounds, such as dehydroepiandrosterone, to pathogenesis and possibly treatment must be considered as well. In this review, we will discuss the recent understandings on how estrogens, estrogen metabolism, dehydroepiandrosterone, and additional susceptibility factors may all contribute to the pathogenesis or potentially to the treatment of pulmonary hypertension, by evaluating current human, cell-based, and experimental model data.

Non-genomic effects of xenoestrogen mixtures

Xenoestrogens (XEs) are chemicals derived from a variety of natural and anthropogenic sources that can interfere with endogenous estrogens by either mimicking or blocking their responses via non-genomic and/or genomic signaling mechanisms. Disruption of estrogens' actions through the less-studied non-genomic pathway can alter such functional end points as cell proliferation, peptide hormone release, catecholamine transport, and apoptosis, among others. Studies of potentially adverse effects due to mixtures and to low doses of endocrine-disrupting chemicals have recently become more feasible, though few so far have included actions via the non-genomic pathway. Physiologic estrogens and XEs evoke non-monotonic dose responses, with different compounds having different patterns of actions dependent on concentration and time, making mixture assessments all the more challenging. In order to understand the spectrum of toxicities and their mechanisms, future work should focus on carefully studying individual and mixture components across a range of concentrations and cellular pathways in a variety of tissue types.

Endocrine disruption via estrogen receptors that participate in nongenomic signaling pathways

When inappropriate (non-physiologic) estrogens affect organisms at critical times of estrogen sensitivity, disruption of normal endocrine functions can result. Non-physiologic estrogen mimetics (environmental, dietary, and pharmaceutical) can signal rapidly and potently via the membrane versions of estrogen receptors, as can physiologic estrogens. Both physiologic and non-physiologic estrogens activate multiple signaling pathways, leading to altered cellular functions (e.g. peptide release, cell proliferation or death, transport). Xenoestrogens' mimicry of physiologic estrogens is imperfect. When superimposed, xenoestrogens can alter endogenous estrogens' signaling and thereby disrupt normal signaling pathways, leading to malfunctions in many tissue types. Though these xenoestrogen actions occur rapidly via nongenomic signaling pathways, they can be sustained with continuing ligand stimulation, combinations of ligands, and signaling that perpetuates downstream, eventually also impinging on genomic regulation by controlling the activation state of transcription factors. Because via these pathways estrogens and xenoestrogens cause nonmonotonic stimulation patterns, they must be carefully tested for activity and toxicity over wide dose ranges. Nongenomic actions of xenoestrogens in combination with each other, and with physiologic estrogens, are still largely unexplored from these mechanistic perspectives.

Estrogen metabolite ratio: Is the 2-hydroxyestrone to 16α-hydroxyestrone ratio predictive for breast cancer?

Experimental studies have shown that two main estrogen metabolites hydroxylated by CYP1A1 and CYP1B1 in the breast differentially affect breast cell proliferation and carcinogenesis. Although 16α-hydroxyestrone (16αOHE1) exerts estrogenic activity through covalent estrogen receptor (ER) binding, 2-hydroxyestrone (2OHE1) presumably has antiestrogenic capabilities. The ratio of 2OHE1 to 16αOHE1 represents the relative dominance of one pathway over the other and is believed to be modifiable by diet. It was hypothesized that women with or at high risk of breast cancer have a lower estrogen metabolite ratio (EMR) compared with women without breast cancer. We conducted a systematic review on the EMR as a predictor for breast cancer. A total of nine studies (six prospective and three retrospective) matched our inclusion criteria, comprising 682 premenopausal cases (1027 controls) and 1189 postmenopausal cases (1888 controls). For the highest compared with the lowest quantile of urinary EMR, nonsignificant associations suggested at best a weak protective effect in premenopausal but not in postmenopausal breast cancer (range of odds ratios: 0.50-0.75 for premenopausal and 0.71-1.31 for postmenopausal). Circulating serum/plasma EMR was not associated with breast cancer risk. Associations were inconclusive for receptor subtypes of breast cancer. Uncontrolled factors known to be involved in breast carcinogenesis, such as 4-hydroxyestrone (4OHE1) concentration, may have confounded results for EMR. Results of the prospective studies do not support the hypothesis that EMR can be used as a predictive marker for breast cancer risk. Future research should concentrate on profiles of estrogen metabolites, including 4OHE1, to gain a more complete picture of the relative importance of single metabolites for breast cancer.

Urinary 2/16 estrogen metabolite ratio levels in healthy women: a review of the literature

This is a summary of the published literature on the urinary 2/16 estrogen metabolite ratio in human populations, and a report the observed range of normal values in healthy women. Original research studies that included the measurement of urinary estrogen metabolites in human subjects were identified through an extensive Medline search; 43 distinct studies were identified, including a total of 6802 healthy women. The range of mean values of the 2/16 ratio measured with the ELISA method varied from 0.98 to 1.74; in studies of pre-menopausal women the range of mean values was 1.5-2.74, in studies of post-menopausal women mean values ranged from 1.15 to 2.25. The heterogeneity across studies was highly significant (p-value Q-test: <0.0001). In multivariable analyses, only race confirmed its role as an independent predictor of 2/16 ratio (F-value: 7.95; p-value: 0.009), after adjustment for age and menopausal status. There appears to be a large body of data on the 2/16 urinary ratio in healthy women. However, summary estimates are difficult to perform due to the high variability of the published study-specific values. The data suggests that race may be a contributor to 2/16 urinary ratio levels.

Soy intake is associated with increased 2-hydroxylation and decreased 16alpha-hydroxylation of estrogens in Asian-American women

INTRODUCTION

In Asian and Asian-American women, soy consumption is associated with reduced breast cancer risk, perhaps due to its effects on estrogen production or metabolism. In a sample of Asian-American women, we investigated the associations of usual adult soy intake with the urinary concentrations of 15 estrogens and estrogen metabolites (EM) measured using liquid chromatography-tandem mass spectrometry.

METHODS

Participants included 430 Chinese-American, Japanese-American, and Filipino-American women, ages 20 to 55 years, and living in San Francisco-Oakland (California), Los Angeles (California), or Oahu (Hawaii). They were postmenopausal (n = 167) or premenopausal in luteal phase (n = 263) when 12-hour urine samples were collected. Robust linear regression was used to assess soy tertiles as predictors of log-transformed EM measures. Individual and grouped EM were considered as concentrations (pmol/mg creatinine) and as percentages of total EM (%EM).

RESULTS

Factor analysis confirmed that EM groups defined by metabolic pathways appropriately captured covariation in EM profiles. Total EM concentrations were not significantly associated with soy in premenopausal or postmenopausal women. Among all women, %2-hydroxylated EM and %4-hydroxylation pathway EM were 16% higher (P(trend) = 0.02) and 19% higher (P(trend) = 0.03) in the highest versus lowest soy tertiles, respectively. In contrast, 16% hydroxylated EM were 11% lower (P(trend) < 0.01). Results were consistent across ethnic and menopausal groups and after adjustment for westernization measured by birthplace (Asia or United States).

DISCUSSION

Findings suggest that regular soy intake is associated with increased ratios of 2:16-pathway EM and with higher relative levels of 4-hydroxylated EM. The observed variations in estrogen metabolism might modify breast cancer risk.

Alterations in oestrogen metabolism: implications for higher penetrance of familial pulmonary arterial hypertension in females

Mutations in bone morphogenetic protein receptor type 2 (BMPR2) cause familial pulmonary arterial hypertension (FPAH), but the penetrance is reduced and females are significantly overrepresented. In addition, gene expression data implicating the oestrogen-metabolising enzyme CYP1B1 suggests a detrimental role of oestrogens or oestrogen metabolites. We examined genetic and metabolic markers of altered oestrogen metabolism in subjects with a BMPR2 mutation. Genotypes for CYP1B1 Asn453Ser (N453S) were determined for 140 BMPR2 mutation carriers (86 females and 54 males). Nested from those subjects, a case-control study of urinary oestrogen metabolite levels (2-hydroxyoestrogen (2-OHE) and 16alpha-hydroxyoestrone (16alpha-OHE(1))) was conducted in females (five affected mutation carriers versus six unaffected mutation carriers). Among females, there was four-fold higher penetrance among subjects homozygous for the wild-type genotype (N/N) than those with N/S or S/S genotypes (p = 0.005). Consistent with this finding, the 2-OHE/16alpha-OHE(1) ratio was 2.3-fold lower in affected mutation carriers compared to unaffected mutation carriers (p = 0.006). Our findings suggest that variations in oestrogens and oestrogen metabolism modify FPAH risk. Further investigation of the role of oestrogens in this disease with profound sex bias may yield new insights and, perhaps, therapeutic interventions.

Polymorphisms in the promoter region of ESR2 gene and breast cancer susceptibility

Genetic variations like single nucleotide polymorphisms (SNPs) in genes involved in estrogen biosynthesis, metabolism and signal transduction have been suggested to affect breast cancer susceptibility. In this study we tested the hypothesis that polymorphisms in the promoter of ESR2 gene may be associated with increased risk for breast cancer. We analyzed three SNPs in the promoter region of human ESR2 gene by means of allele-specific tetra-primer PCR. A total of 318 sporadic breast cancer cases and 318 age-matched controls were included in the study. With regard to homozygous genotypes, women with sporadic breast cancer more frequently carried the CC genotype of ESR2 promoter SNP rs2987983 (OR 1.99, p=0.005). Calculation of allele positivity demonstrated that presence of T allele of this SNP was more frequent in healthy women. Our data suggest that a SNP in the promoter region of ESR2 gene might be able to affect breast cancer risk. These results further support the emerging hypothesis that ERbeta is an important factor in breast cancer development.

Nongenomic actions of estradiol compared with estrone and estriol in pituitary tumor cell signaling and proliferation

Physiological estrogens, including estrone (E(1)), estradiol (E(2)), and estriol (E(3)), fluctuate with life stage, suggesting specific roles for them in biological and disease processes. We compared their nongenomic signaling and functional actions in GH3/B6/F10 rat pituitary tumor cells. All hormones caused prolactin release at 1 min; the lowest effective concentrations were 10(-11) M E(2), 10(-10) M E(1), and 10(-7) M E(3). All estrogens increased the oscillation frequency of calcium (Ca) spikes, with the same time delay (approximately 200 s) at all levels (10(-15) to 10(-9) M). At some concentrations, E(1) and E(3) provoked more Ca-responding cells than E(2). The amplitude and volume of Ca peaks were elevated by all hormones at > or = 10(-15) M. All hormones caused cell proliferation, with the lowest effective concentrations of E(2) (10(-15) M) > E(1) (10(-12) M) > E(3) (10(-10) M); E(2) caused higher maximal cell numbers at most concentrations. All estrogens caused oscillating extracellular-regulated kinase (ERK) activations, with relative potencies of E(1) and E(2) > E(3). All estrogens were ineffective in activation of ERKs or causing proliferation in a subline expressing low levels of membrane estrogen receptor-alpha. Dose-response patterns were frequently nonmonotonic. Therefore, the hormones E(1) and E(3), which have been designated "weak" estrogens in genomic actions, are strong estrogens in the nongenomic signaling pathways and functional responses in the pituitary.