Explore the vast range of titles available.

Androgen biosynthesis in the human fetus proceeds through the adrenal sex steroid precursor dehydroepiandrosterone, which is converted to testosterone in the gonads, followed by further activation to 5α-dihydrotestosterone in genital skin, thereby facilitating male external genital differentiation. Congenital adrenal hyperplasia due to P450 oxidoreductase deficiency results in disrupted dehydroepiandrosterone biosynthesis, explaining undervirilization in affected boys. However, many affected girls are born virilized, despite low circulating androgens. We hypothesized that this is due to a prenatally active, alternative androgen biosynthesis pathway from 17α-hydroxyprogesterone to 5α-dihydrotestosterone, which bypasses dehydroepiandrosterone and testosterone, with increased activity in congenital adrenal hyperplasia variants associated with 17α-hydroxyprogesterone accumulation. Here we employ explant cultures of human fetal organs (adrenals, gonads, genital skin) from the major period of sexual differentiation and show that alternative pathway androgen biosynthesis is active in the fetus, as assessed by liquid chromatography–tandem mass spectrometry. We found androgen receptor expression in male and female genital skin using immunohistochemistry and demonstrated that both 5α-dihydrotestosterone and adrenal explant culture supernatant induce nuclear translocation of the androgen receptor in female genital skin primary cultures. Analyzing urinary steroid excretion by gas chromatography–mass spectrometry, we show that neonates with P450 oxidoreductase deficiency produce androgens through the alternative androgen pathway during the first weeks of life. We provide quantitative in vitro evidence that the corresponding P450 oxidoreductase mutations predominantly support alternative pathway androgen biosynthesis. These results indicate a key role of alternative pathway androgen biosynthesis in the prenatal virilization of girls affected by congenital adrenal hyperplasia due to P450 oxidoreductase deficiency.

Key Points Prostate cancers are capable of intratumoural androgen biosynthesis, which is a potential mechanism of castration resistance Three possible competing androgen biosynthesis pathways exist, all of which might enable androgen biosynthesis in the presence of androgen-deprivation therapy Currently, investigations of androgen biosynthesis rely heavily on preclinical models, which generally do not accurately reflect human disease in this setting Identifying the dominant androgen biosynthetic pathway in each patient could have implications for treatment-related decisions Treatment with androgen-deprivation therapy can delay the progression of prostate cancer. However, acquired resistance to such approaches is very common. Here the authors describe the role of androgen synthesis pathways, including the specific relevance of each individual pathway, to the development of castration-resistant prostate cancer. The accumulation of high concentrations of signalling androgens within prostate tumours that progress despite use of androgen-deprivation therapy is a clinically important mechanism of the development of castration-resistant prostate cancer. In the past 5 years, data from a number of studies have increased our understanding of the enzymes and substrates involved in intratumoural androgen biosynthesis, and have implicated three competing pathways, which are likely to account for these observations. These pathways ('canonical', 'backdoor' and '5α-dione'), which can all ultimately generate the potent signalling androgen, dihydrotestosterone, involve many of the same enzymes, but differ in terms of substrate preference, reaction sequence and the organs and tissues in which they occur. For this reason, the relative importance of each pathway to the development and progression of prostate cancer remains controversial. In this Review, we describe the current understanding of androgen synthesis and the evidence for its role in castration resistance, and examine the evidence supporting and or rebutting the relevance of each pathway to patients with prostate cancer.

Targeting the androgen receptor (AR) signaling axis has been, over decades, the mainstay of prostate cancer therapy. More potent inhibitors of androgen synthesis and antiandrogens have emerged and have been successfully implemented in clinical practice. That said, the stronger inhibition of the AR signaling axis has led in recent years to an increase of prostate cancers that de-differentiate into AR-negative disease. Unfortunately, this process is intimately linked with a poor prognosis. Here, we review the molecular mechanisms that enable cancer cells to switch from an AR-positive to an AR-negative disease and efforts to prevent/revert this process and thereby maintain/restore AR-dependence.

The drug abiraterone is converted to Δ 4 -abiraterone (D4A) in mice and patients with prostate cancer, which has more potent anti-tumour activity and may lead to more effective therapies. Alternatives to abiraterone in prostate cancer Abiraterone has been designed as a drug to treat patients with co-called castration-resistant prostate cancer — cancers that don't respond to androgen antagonists. Abiraterone works instead by blocking the formation of androgens via inhibition of the enzyme CYP17A1, a key step in the biosynthesis of testosterone and other androgens. In a new twist to these findings, Nima Sharifi and colleagues now show that abiraterone is itself metabolized in prostate tumours, giving rise to D4A which inhibits several enzymes in the androgen synthesis pathway including CYP17A1 and also antagonizes the androgen receptor. D4A has more potent anti-tumour activity in animal models, and may lead to more efficient therapies, in particular in the light of certain restrictions to the availability of abiraterone. Prostate cancer resistance to castration occurs because tumours acquire the metabolic capability of converting precursor steroids to 5α-dihydrotestosterone (DHT), promoting signalling by the androgen receptor and the development of castration-resistant prostate cancer 1 , 2 , 3 . Essential for resistance, DHT synthesis from adrenal precursor steroids or possibly from de novo synthesis from cholesterol commonly requires enzymatic reactions by 3β-hydroxysteroid dehydrogenase (3βHSD), steroid-5α-reductase (SRD5A) and 17β-hydroxysteroid dehydrogenase (17βHSD) isoenzymes 4 , 5 . Abiraterone, a steroidal 17α-hydroxylase/17,20-lyase (CYP17A1) inhibitor, blocks this synthetic process and prolongs survival 6 , 7 . We hypothesized that abiraterone is converted by an enzyme to the more active Δ 4 -abiraterone (D4A), which blocks multiple steroidogenic enzymes and antagonizes the androgen receptor, providing an additional explanation for abiraterone’s clinical activity. Here we show that abiraterone is converted to D4A in mice and patients with prostate cancer. D4A inhibits CYP17A1, 3βHSD and SRD5A, which are required for DHT synthesis. Furthermore, competitive androgen receptor antagonism by D4A is comparable to the potent antagonist enzalutamide. D4A also has more potent anti-tumour activity against xenograft tumours than abiraterone. Our findings suggest an additional explanation—conversion to a more active agent—for abiraterone’s survival extension. We propose that direct treatment with D4A would be more clinically effective than abiraterone treatment.

In this study, abiraterone acetate inhibited androgen synthesis and prolonged survival by 4 months among men with castration-resistant prostate cancer that had progressed with docetaxel chemotherapy. For the past 70 years, depleting or blocking the action of androgens has been the standard of care for men with advanced prostate cancer. 1 Androgen deprivation results in a decrease in the concentration of prostate-specific antigen (PSA) as well as tumor regression and relief of symptoms in most patients, but the response to treatment is not durable in patients with advanced cancer, and with time, PSA concentrations increase, indicating reactivated androgen-receptor signaling and a transition to a castration-resistant state that is invariably fatal. 2 Many endocrine therapies have been evaluated in these patients, but none have prolonged survival. 3 Three nonhormonal systemic . . .

Liquid biopsies have demonstrated that the constitutively active androgen receptor splice variant-7 (AR-V7) associates with reduced response and overall survival from endocrine therapies in castration-resistant prostate cancer (CRPC). However, these studies provide little information pertaining to AR-V7 expression in prostate cancer (PC) tissue. Following generation and validation of a potentially novel AR-V7 antibody for IHC, AR-V7 protein expression was determined for 358 primary prostate samples and 293 metastatic biopsies. Associations with disease progression, full-length androgen receptor (AR-FL) expression, response to therapy, and gene expression were determined. We demonstrated that AR-V7 protein is rarely expressed (<1%) in primary PC but is frequently detected (75% of cases) following androgen deprivation therapy, with further significant (P = 0.020) increase in expression following abiraterone acetate or enzalutamide therapy. In CRPC, AR-V7 expression is predominantly (94% of cases) nuclear and correlates with AR-FL expression (P ≤ 0.001) and AR copy number (P = 0.026). However, dissociation of expression was observed, suggesting that mRNA splicing remains crucial for AR-V7 generation. AR-V7 expression was heterogeneous between different metastases from a patient, although AR-V7 expression was similar within a metastasis. Moreover, AR-V7 expression correlated with a unique 59-gene signature in CRPC, including HOXB13, a critical coregulator of AR-V7 function. Finally, AR-V7-negative disease associated with better prostate-specific antigen (PSA) responses (100% vs. 54%, P = 0.03) and overall survival (74.3 vs. 25.2 months, hazard ratio 0.23 [0.07-0.79], P = 0.02) from endocrine therapies (pre-chemotherapy). This study provides impetus to develop therapies that abrogate AR-V7 signaling to improve our understanding of AR-V7 biology and to confirm the clinical significance of AR-V7. Work at the University of Washington and in the Plymate and Nelson laboratories is supported by the Department of Defense Prostate Cancer Research Program (W81XWH-14-2-0183, W81XWH-12-PCRP-TIA, W81XWH-15-1-0430, and W81XWH-13-2-0070), the Pacific Northwest Prostate Cancer SPORE (P50CA97186), the Institute for Prostate Cancer Research, the Veterans Affairs Research Program, the NIH/National Cancer Institute (P01CA163227), and the Prostate Cancer Foundation. Work in the de Bono laboratory was supported by funding from the Movember Foundation/Prostate Cancer UK (CEO13-2-002), the US Department of Defense (W81XWH-13-2-0093), the Prostate Cancer Foundation (20131017 and 20131017-1), Stand Up To Cancer (SU2C-AACR-DT0712), Cancer Research UK (CRM108X-A25144), and the UK Department of Health through an Experimental Cancer Medicine Centre grant (ECMC-CRM064X).

The prostate cancer drug abiraterone can be metabolized into several substances with different effects, and optimization of this process could be helpful for fine-tuning the treatment of prostate cancer. Manipulating antitumour activity of abiraterone The anti-androgen prostate cancer drug abiraterone is metabolized in the body to Δ4-abiraterone (D4A), a more potent steroid than abiraterone with structural similarities to endogenous steroidal 5α-reductase substrates, such as testosterone. These authors show that D4A is converted in the body to at least six previously unrecognized metabolites with a range of different metabolic effects. In a clinical trial of abiraterone alone, followed by abiraterone plus the 5α-reductase inhibitor dutasteride, production of a downstream tumour-promoting metabolite was blocked and D4A concentrations rose. These findings suggest a previously unappreciated method of clinically fine-tuning abiraterone metabolism to optimize cancer therapy. Abiraterone blocks androgen synthesis and prolongs survival in patients with castration-resistant prostate cancer, which is otherwise driven by intratumoral androgen synthesis 1 , 2 . Abiraterone is metabolized in patients to Δ 4 -abiraterone (D4A), which has even greater anti-tumour activity and is structurally similar to endogenous steroidal 5α-reductase substrates, such as testosterone 3 . Here, we show that D4A is converted to at least three 5α-reduced and three 5β-reduced metabolites in human serum. The initial 5α-reduced metabolite, 3-keto-5α-abiraterone, is present at higher concentrations than D4A in patients with prostate cancer taking abiraterone, and is an androgen receptor agonist, which promotes prostate cancer progression. In a clinical trial of abiraterone alone, followed by abiraterone plus dutasteride (a 5α-reductase inhibitor), 3-keto-5α-abiraterone and downstream metabolites were depleted by the addition of dutasteride, while D4A concentrations rose, showing that dutasteride effectively blocks production of a tumour-promoting metabolite and permits D4A accumulation. Furthermore, dutasteride did not deplete the three 5β-reduced metabolites, which were also clinically detectable, demonstrating the specific biochemical effects of pharmacological 5α-reductase inhibition on abiraterone metabolism. Our findings suggest a previously unappreciated and biochemically specific method of clinically fine-tuning abiraterone metabolism to optimize therapy.

Previous studies have demonstrated that androgen receptor is expressed in many breast cancers, but its expression in relation to the various breast cancer subtypes as defined by molecular profiling has not been studied in detail. We constructed tissue microarrays from 3093 breast cancers that developed in women enrolled in the Nurses' Health Study. Tissue microarray sections were immunostained for estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), cytokeratin 5/6, epidermal growth factor receptor (EGFR) and androgen receptor (ER). Immunostain results were used to categorize each cancer as luminal A or B, HER2 and basal like. The relationships between androgen receptor expression and molecular subtype were analyzed. Overall, 77% of the invasive breast carcinomas were androgen receptor positive. Among 2171 invasive cancers, 64% were luminal A, 15% luminal B, 6% HER2 and 11% basal like. The frequency of androgen receptor expression varied significantly across the molecular phenotypes ( P <0.0001). In particular, androgen receptor expression was commonly observed in luminal A (91%) and B (68%) cancers, but was less frequently seen in HER2 cancers (59%). Despite being defined by the absence of ER and PR expression and being considered hormonally unresponsive, 32% of basal-like cancers expressed androgen receptor. Among 246 cases of ductal carcinoma in situ , 86% were androgen receptor positive, but the frequency of androgen receptor expression differed significantly across the molecular phenotypes ( P =0.001), and high nuclear grade lesions were less likely to be androgen receptor positive compared with lower-grade lesions. Androgen receptor expression is most commonly seen in luminal A and B invasive breast cancers. However, expression of androgen receptor is also seen in approximately one-third of basal-like cancers, providing further evidence that basal-like cancers represent a heterogeneous group. Our findings raise the possibility that targeting the androgen receptor pathway may represent a novel therapeutic approach to the management of patients with basal-like cancers.

Masculinization of the external genitalia in humans is dependent on formation of 5α-dihydrotestosterone (DHT) through both the canonical androgenic pathway and an alternative (backdoor) pathway. The fetal testes are essential for canonical androgen production, but little is known about the synthesis of backdoor androgens, despite their known critical role in masculinization. In this study, we have measured plasma and tissue levels of endogenous steroids in second trimester human fetuses using multidimensional and high-resolution mass spectrometry. Results show that androsterone is the principal backdoor androgen in the male fetal circulation and that DHT is undetectable (<1 ng/mL), while in female fetuses, there are significantly lower levels of androsterone and testosterone. In the male, intermediates in the backdoor pathway are found primarily in the placenta and fetal liver, with significant androsterone levels also in the fetal adrenal. Backdoor intermediates, including androsterone, are only present at very low levels in the fetal testes. This is consistent with transcript levels of enzymes involved in the alternate pathway (steroid 5α-reductase type 1 [SRD5A1], aldo-keto reductase type 1C2 [AKR1C2], aldo-keto reductase type 1C4 [AKR1C4], cytochrome P450 17A1 [CYP17A1]), as measured by quantitative PCR (qPCR). These data identify androsterone as the predominant backdoor androgen in the human fetus and show that circulating levels are sex dependent, but also that there is little de novo synthesis in the testis. Instead, the data indicate that placental progesterone acts as substrate for synthesis of backdoor androgens, which occurs across several tissues. Masculinization of the human fetus depends, therefore, on testosterone and androsterone synthesis by both the fetal testes and nongonadal tissues, leading to DHT formation at the genital tubercle. Our findings also provide a solid basis to explain why placental insufficiency is associated with disorders of sex development in humans.

Genomic analysis of a single metastasis informs about the oncogenic—and potentially druggable—genomic alterations present in other tumors within the same man with metastatic prostate cancer. Tumor heterogeneity may reduce the efficacy of molecularly guided systemic therapy for cancers that have metastasized. To determine whether the genomic alterations in a single metastasis provide a reasonable assessment of the major oncogenic drivers of other dispersed metastases in an individual, we analyzed multiple tumors from men with disseminated prostate cancer through whole-exome sequencing, array comparative genomic hybridization (CGH) and RNA transcript profiling, and we compared the genomic diversity within and between individuals. In contrast to the substantial heterogeneity between men, there was limited diversity among metastases within an individual. The number of somatic mutations, the burden of genomic copy number alterations and aberrations in known oncogenic drivers were all highly concordant, as were metrics of androgen receptor (AR) activity and cell cycle activity. AR activity was inversely associated with cell proliferation, whereas the expression of Fanconi anemia (FA)-complex genes was correlated with elevated cell cycle progression, expression of the E2F transcription factor 1 ( E2F1 ) and loss of retinoblastoma 1 ( RB1 ). Men with somatic aberrations in FA-complex genes or in ATM serine/threonine kinase ( ATM ) exhibited significantly longer treatment-response durations to carboplatin than did men without defects in genes encoding DNA-repair proteins. Collectively, these data indicate that although exceptions exist, evaluating a single metastasis provides a reasonable assessment of the major oncogenic driver alterations that are present in disseminated tumors within an individual, and thus may be useful for selecting treatments on the basis of predicted molecular vulnerabilities.