Phase two steroid metabolism and its roles in breast and prostate cancer patients

High throughput LC-MS/MS method for steroid hormone analysis in rat liver and plasma - unraveling methodological challenges

Comprehensive reference data for steroid hormones are lacking in rat models, particularly for early developmental stages and unconventional matrices as the liver. Therefore, we developed and validated an enzymatic, solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify a panel of 23 steroid hormones in liver and plasma from adult and neonatal rats. Our approach tackles methodological challenges, focusing on undesired byproducts associated with specific enzymatic treatment, and enables a thorough assessment of potential interferences in complex matrices by utilizing unstripped plasma and liver. We propose an optimized enzymatic hydrolysis protocol using a recombinant β-glucuronidase/sulfatase mix (BGS mix) to efficiently deconjugate steroid phase II conjugates. The streamlined sample preparation and high-throughput solid phase extraction in a 96-well plate significantly accelerate sample processing for complex matrices and alarge number of samples. We were able to achieve the necessary sensitivity for accurately measuring the target analytes, particularly estrogens, in small sample sizes of 5-20 mg of liver tissue and 100 μL of plasma. Through the analysis of liver and plasma samples from adult and neonatal rats, including both sexes, our study showed a novel set of steroid hormone reference intervals. This study provides a reliable diagnostic tool for the quantification of steroids in rat models and gives insight in liver and plasma-related steroid hormone dynamics at early developmental stages. In addition, the method covers several pathway intermediates and extend the list of steroid hormones to be investigated.

Circulating Conjugated and Unconjugated Vitamin D Metabolite Measurements by Liquid Chromatography Mass Spectrometry

CONTEXT

Vitamin D status is conventionally defined by measurement of unconjugated circulating 25-hydroxyvitamin D (25OHD), but it remains uncertain whether this isolated analysis gives sufficient weight to vitamin D's diverse metabolic pathways and bioactivity. Emerging evidence has shown that phase II endocrine metabolites are important excretory or storage forms; however, the clinical significance of circulating phase II vitamin D metabolites remains uncertain.

OBJECTIVE

In this study we analyzed the contribution of sulfate and glucuronide vitamin D metabolites relative to unconjugated levels in human serum.

METHODS

An optimized enzyme hydrolysis method using recombinant arylsulfatase (Pseudomonas aeruginosa) and beta-glucuronidase (Escherichia coli) was combined with liquid chromatography mass spectrometry (LC-MS/MS) analysis to measure conjugated and unconjugated vitamin D metabolites 25OHD3, 25OHD2, 3-epi-25OHD3, and 24,25(OH)2D3. The method was applied to the analysis of 170 human serum samples from community-dwelling men aged over 70 years, categorized by vitamin D supplementation status, to evaluate the proportions of each conjugated and unconjugated fraction.

RESULTS

As a proportion of total circulating vitamin D metabolites, sulfate conjugates (ranging between 18% and 53%) were a higher proportion than glucuronide conjugates (ranging between 2.7% and 11%). The proportion of conjugated 25OHD3 (48 ± 9%) was higher than 25OHD2 conjugates (29.1 ± 10%) across all supplementation groups. Conjugated metabolites correlated with their unconjugated forms for all 4 vitamin D metabolites (r = 0.85 to 0.97).

CONCLUSION

Sulfated conjugates form a high proportion of circulating vitamin D metabolites, whereas glucuronide conjugates constitute a smaller fraction. Our findings principally in older men highlight the differences in abundance between metabolites and suggest a combination of both conjugated and unconjugated measurements may provide a more accurate assessment of vitamin D status.

The 11β-hydroxyandrostenedione pathway and C11-oxy C21 backdoor pathway are active in benign prostatic hyperplasia yielding 11keto-testosterone and 11keto-progesterone

In clinical approaches to benign prostatic hyperplasia (BPH) and prostate cancer (PCa), steroidogenesis or the disruption thereof is the main thrust in treatments restricting active androgen production. Extensive studies have been undertaken focusing on testosterone and dihydrotestosterone (DHT). However, the adrenal C11-oxy C₁₉ steroid, 11β-hydroxyandrostenedione (11OHA4), also contributes to the active androgen pool in the prostate microenvironment, and while it has been shown to impact castration resistant prostate cancer, the C11-oxy C₁₉ steroids together with the C11-oxy C₂₁ steroids have not been studied in BPH. The study firstly investigated the metabolism of these adrenal steroids in the BPH-1 model. Comprehensive profiles identified 11keto-testosterone as the predominant active androgen in the metabolism of the C11-oxy C₁₉ steroids, and we identified, for the first time, 11β-hydroxy-5α-androstane-3α,17β-diol, a novel steroid in the 11OHA4-pathway. Analysis of the inactivation and reactivation of the metabolites showed that DHT is more readily inactivated than 11keto-dihydrotestosterone (11KDHT). The conversion of 11β-hydroxyprogesterone (11βOHPROG) yielded 11keto-progesterone (11KPROG), while the latter yielded 11keto-dihydroprogesterone (11KDHPROG). BPH tissue analysis identified high levels of 11β-hydroxyandrosterone (4-14 ng/g) and 11keto-androsterone (9-160 ng/g), together with androstenedione (A4; ∼7.5 ng/g). The major C11-oxy C₂₁ steroids detected were 11βOHPROG (∼46 ng/g), 11KPROG (∼130 ng/g) as well as 11KDHPROG (∼282 ng/g). While circulatory 11βOHPROG was detected below the limit of quantification, 11KPROG and 11KDHPROG were detected at 6 and 8.5 nmol/L, respectively. Glucuronide derivatives of both 11KPROG and pregnanetriol were also detected. 11OHA4 was the major free androgen in circulation at 85.9 nmol/L, ±12-fold higher than A4, together with 5α-androstane-3α,17β-diol quantified at 69.3 nmol/L. Circulatory C11-oxy C₁₉ steroids levels were also significantly higher (8-fold) than the C11-oxy C₂₁ steroid levels, while the former were similar to the C₁₉ steroid levels, in contrast to levels in PCa. The study highlights the contribution of adrenal C11-oxy steroids to the androgen pool in BPH underscoring their limited reactivation and elimination, and significant inter-individual variations regarding steroid levels and conjugation. Targeted steroid metabolome analysis is critical to understanding prostate steroidogenesis and disease progression, and analysis of circulatory C11-oxy C₁₉ and C11-oxy C₂₁ steroids, together with intraprostatic levels, add to our current understanding of BPH.

Adrenal androgens rescue prostatic dihydrotestosterone production and growth of prostate cancer cells after castration

Adrenal androgens dehydroepiandrosterone (DHEA) and DHEA-sulfate (DHEAS) are potential substrates for intracrine production of testosterone (T) and dihydrotestosterone (DHT), or directly to DHT, by prostate cancer (PCa) cells. Production of DHT from DHEAS and DHEA, and the role of steroid sulfatase (STS), were evaluated ex vivo using fresh human prostate tissue and in vitro using human PCa cell lines. STS was expressed in benign prostate tissue and PCa tissue. DHEAS at a physiological concentration was converted to DHT in prostate tissue and PCa cell lines, which was STS-dependent. DHEAS activation of androgen receptor (AR) and stimulation of PCa cell growth were STS-dependent. DHEA at a physiological concentration was not converted to DHT ex vivo and in vitro, but stimulated in vivo tumor growth of the human PCa cell line, VCaP, in castrated mice. The findings suggest that targeting metabolism of DHEAS and DHEA may enhance androgen deprivation therapy.

Steroid metabolism in breast cancer: Where are we and what are we missing?

It is well-known that breast cancer is hormone-dependent and that steroid hormones exert their mitogenic effects by binding to estrogen, progesterone and androgen receptors. Vital to our understanding and treatment of this malignancy, is the local metabolism of steroid hormones in breast cancer tissue. This review summarises our current knowledge on steroid producing pathways in the adrenal, ovary and breast, while focussing on the availability of specific circulating hormone precursors and steroidogenic enzymes involved in the local synthesis and metabolism of steroid hormones in the breast. Consequently, we highlight alternate pathways that may be instrumental in the etiology of breast cancer.

Intracrine androgen biosynthesis, metabolism and action revisited

Androgens play an important role in metabolic homeostasis and reproductive health in both men and women. Androgen signalling is dependent on androgen receptor activation, mostly by testosterone and 5α-dihydrotestosterone. However, the intracellular or intracrine activation of C19 androgen precursors to active androgens in peripheral target tissues of androgen action is of equal importance. Intracrine androgen synthesis is often not reflected by circulating androgens but rather by androgen metabolites and conjugates. In this review we provide an overview of human C19 steroid biosynthesis including the production of 11-oxygenated androgens, their transport in circulation and uptake into peripheral tissues. We conceptualise the mechanisms of intracrinology and review the intracrine pathways of activation and inactivation in selected human tissues. The contribution of liver and kidney as organs driving androgen inactivation and renal excretion are also highlighted. Finally, the importance of quantifying androgen metabolites and conjugates to assess intracrine androgen production is discussed.

Linking physiologically-based pharmacokinetic and genome-scale metabolic networks to understand estradiol biology

Background

Estrogen is a vital hormone that regulates many biological functions within the body. These include roles in the development of the secondary sexual organs in both sexes, plus uterine angiogenesis and proliferation during the menstrual cycle and pregnancy in women. The varied biological roles of estrogens in human health also make them a therapeutic target for contraception, mitigation of the adverse effects of the menopause, and treatment of estrogen-responsive tumours. In addition, endogenous (e.g. genetic variation) and external (e.g. exposure to estrogen-like chemicals) factors are known to impact estrogen biology. To understand how these multiple factors interact to determine an individual’s response to therapy is complex, and may be best approached through a systems approach.

Methods

We present a physiologically-based pharmacokinetic model (PBPK) of estradiol, and validate it against plasma kinetics in humans following intravenous and oral exposure. We extend this model by replacing the intrinsic clearance term with: a detailed kinetic model of estrogen metabolism in the liver; or, a genome-scale model of liver metabolism. Both models were validated by their ability to reproduce clinical data on estradiol exposure. We hypothesise that the enhanced mechanistic information contained within these models will lead to more robust predictions of the biological phenotype that emerges from the complex interactions between estrogens and the body.

Results

To demonstrate the utility of these models we examine the known drug-drug interactions between phenytoin and oral estradiol. We are able to reproduce the approximate 50% reduction in area under the concentration-time curve for estradiol associated with this interaction. Importantly, the inclusion of a genome-scale metabolic model allows the prediction of this interaction without directly specifying it within the model. In addition, we predict that PXR activation by drugs results in an enhanced ability of the liver to excrete glucose. This has important implications for the relationship between drug treatment and metabolic syndrome.

Conclusions

We demonstrate how the novel coupling of PBPK models with genome-scale metabolic networks has the potential to aid prediction of drug action, including both drug-drug interactions and changes to the metabolic landscape that may predispose an individual to disease development.

Electronic supplementary material

The online version of this article (10.1186/s12918-017-0520-3) contains supplementary material, which is available to authorized users.

Androgen and AR contribute to breast cancer development and metastasis: an insight of mechanisms

The role of androgen and androgen receptor (AR) in breast carcinogenesis has long been a disputed issue. This report provides a mechanistic insight into how androgen and AR contributes to invasion and metastasis of breast cancer. We find that dihydrotestosterone (DHT) is able to induce the epithelial-to-mesenchymal transition in breast cancer cells in an AR-dependent/estrogen receptor-independent manner. This process is dependent on the demethylation activity of lysine-specific demethylase 1A (LSD1) by epigenetically regulating the target genes E-cadherin and vimentin. In vivo, DHT promotes metastasis in a nude mouse model, and AR and LSD1 are indispensable in this process. We establish that higher expression of nucleus AR to cytoplasm AR associated with worse prognostic outcomes in breast cancer patient samples. This study maps an 'androgen-AR/LSD1-target genes' pathway in breast carcinogenesis, implicating the importance of hormonal balance in women, and the potential clinical significance of serum androgen and AR in prediction of breast cancer and selection of breast cancer therapy.

How far have we come in terms of estrogens in breast cancer? [Review]

Major advances in breast cancer treatment have almost always been linked to the actions of estrogen. Therefore, this review focused on estrogen actions in the breast, particularly the developments of the past 20 years, the present understanding of disease biology and possible future developments. Within these areas have focused on what is known about the underlying molecular biology and in particular integration of the bioinformatics revolution of the last 15 years with other facets of research. In addition, there will be an emphasis on the understanding brought about by a greater appreciation for the intracrinology of the breast.

The intracrinology of breast cancer

The importance of intracrinology, or in situ production of steroids from circulating precursors, in breast cancer has been firmly established in estrogen actions on postmenopausal patients. Expression levels of various steroid synthesizing and/or metabolizing enzymes have been examined in human breast cancer tissues by a number of groups. The enzymes examined include those capable of converting circulating DHEA-S to sex steroids (STS and 3βHSDΔ4-5 isomerase), the group of enzymes that modulate the strength of both androgens and estrogens (17βHSD family) as well as the androgenic 5αR enzymes and the estrogenic aromatase enzyme. In addition to these DHEA-related metabolism pathways, other intracrine pathways involving progesterone and cholesterol have also been examined. Some risk factors of breast cancer development, including obesity, have also been postulated to interact with steroid metabolising pathways. In this review, we aimed to summarise the current state of knowledge regarding intracrine metabolism including expression levels of various enzymes and receptors, focusing particularly upon the importance of the production of biologically potent steroids from circulating sulfated precursors such as DHEA-S. In addition, we attempted to summarise the factors, both steroidal and non-steroidal, involved in the regulation of these enzymes and propose future directions for research in this particular field. The concept of intracrinology was first proposed over 20 years ago but there still remain many unanswered questions which could open new horizons for the understanding of intracrine metabolism in the breast. This article is part of a Special Issue entitled 'Essential role of DHEA'.

Sex steroid metabolism in benign and malignant intact prostate biopsies: individual profiling of prostate intracrinology

In vitro studies reveal that androgens, oestrogens, and their metabolites play a crucial role in prostate homeostasis. Most of the studies evaluated intraprostatic hormone metabolism using cell lines or preprocessed specimens. Using an ex vivo model of intact tissue cultures with preserved architecture, we characterized the enzymatic profile of biopsies from patients with benign prostatic hyperplasia (BPH) or cancer (PC), focusing on 17β-hydroxy-steroid-dehydrogenases (17β-HSDs) and aromatase activities. Samples from 26 men who underwent prostate needle core biopsies (BPH n = 14; PC n = 12) were incubated with radiolabeled ³H-testosterone or ³H-androstenedione. Conversion was evaluated by TLC separation and beta-scanning of extracted supernatants. We identified three major patterns of conversion. The majority of BPHs revealed no active testosterone/oestradiol conversion as opposed to prostate cancer. Conversion correlated with histology and PSA, but not circulating hormones. Highest Gleason scores had a higher androstenedion-to-testosterone conversion and expression of 17β-HSD-isoenzymes-3/5. Conclusions. We developed an easy tool to profile individual intraprostatic enzymatic activity by characterizing conversion pathways in an intact tissue environment. In fresh biopsies we found that 17β-HSD-isoenzymes and aromatase activities correlate with biological behaviour allowing for morphofunctional phenotyping of pathology specimens and clinical monitoring of novel enzyme-targeting drugs.

A guide to understanding the steroid pathway: new insights and diagnostic implications

Steroid analysis has always been complicated requiring a clear understanding of both the clinical and analytical aspects in order to accurately interpret results. The literature relating to this specialised area spans many decades and the intricacies of the steroid pathway have evolved with time. A number of key changes, including discovery of the alternative androgen pathway, have occurred in the last decade, potentially changing our understanding and approach to investigating disorders of sexual development. Such investigation usually occurs in specialised paediatric centres and although preterm infants represent only a small percentage of the patient population, consideration of the persistence of the foetal adrenal zone is an additional important consideration when undertaking steroid hormone investigations. The recent expanded role of mass spectrometry and molecular diagnostic methods provides significant improvements for accurate steroid quantification and identification of enzyme deficiencies. However analysis of steroids and interpretation of results remain complicated. This review aims to provide an insight into the complexities of steroid measurement in children and offers an updated guide to interpretation, of serum and urine steroids through the presentation of a refined steroid pathway.