Summary Growth of prostate cancer cells is dependent upon androgen stimulation of the androgen receptor (AR). Dihydrotestosterone (DHT), the most potent androgen, is usually synthesized in the prostate from testosterone secreted by the testis. Following chemical or surgical castration, prostate cancers usually shrink owing to testosterone deprivation. However, tumors often recur, forming castration-resistant prostate cancer (CRPC). Here, we show that CRPC sometimes expresses a gain-of-stability mutation leading to a gain-of-function in 3β-hydroxysteroid dehydrogenase type 1 (3βHSD1), which catalyzes the initial rate-limiting step in the conversion of the adrenal-derived steroid dehydroepiandrosterone to DHT. The mutation (N367T) does not affect catalytic function, but it renders the enzyme resistant to ubiquitination and degradation, leading to profound accumulation. Whereas dehydroepiandrosterone conversion to DHT is usually very limited, expression of 367T accelerates this conversion and provides the DHT necessary to activate the AR. We suggest that 3βHSD1 is a valid target for the treatment of CRPC.

SummaryProstate cancer resistance to castration occurs because tumors acquire the metabolic capability of converting precursor steroids to 5α-dihydrotestosterone (DHT), promoting signaling by the androgen receptor (AR) and the development of castration-resistant prostate cancer (CRPC)1–3. Essential for resistance, DHT synthesis from adrenal precursor steroids or possibly from de novo synthesis from cholesterol commonly require enzymatic reactions by 3β-hydroxysteroid dehydrogenase (3βHSD), steroid-5α-reductase (SRD5A) and 17β-hydroxysteroid dehydrogenase (17βHSD) isoenzymes4,5. Abiraterone, a steroidal 17α-hydroxylase/17,20-lyase (CYP17A1) inhibitor, blocks this synthetic process and prolongs survival6,7. We hypothesized that abiraterone is converted by an enzyme to the more active Δ4-abiraterone (D4A) that blocks multiple steroidogenic enzymes and antagonizes the androgen receptor (AR), 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 AR antagonism by D4A is comparable to the potent antagonist, enzalutamide. D4A also has more potent antitumor activity against xenograft tumors 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.

Integral membrane proteins (IMPs) play crucial roles in all cells and represent attractive pharmacological targets. However, functional and structural studies of IMPs are hindered by their hydrophobic nature and the fact that they are generally unstable following extraction from their native membrane environment using detergents. Here we devise a general strategy for in vivo solubilization of IMPs in structurally relevant conformations without the need for detergents or mutations to the IMP itself, as an alternative to extraction and in vitro solubilization. This technique, called SIMPLEx (solubilization of IMPs with high levels of expression), allows the direct expression of soluble products in living cells by simply fusing an IMP target with truncated apolipoprotein A-I, which serves as an amphipathic proteic ‘shield' that sequesters the IMP from water and promotes its solubilization.

Purpose: Treatment with abiraterone (abi) acetate prolongs survival in castration-resistant prostate cancer (CRPC). Resistance to abi invariably occurs, probably due in part to upregulation of steroidogenic enzymes and/or other mechanisms that sustain dihydrotestosterone (DHT) synthesis, which raises the possibility of reversing resistance by concomitant inhibition of other required steroidogenic enzymes. On the basis of the 3b-hydroxyl, D 5 -structure, we hypothesized that abi also inhibits 3b-hydroxysteroid dehydrogenase/isomerase (3bHSD), which is absolutely required for DHT synthesis in CRPC, regardless of origins or routes of synthesis. Experimental Design: We tested the effects of abi on 3bHSD activity, androgen receptor localization, expression of androgen receptor-responsive genes, and CRPC growth in vivo.Results: Abi inhibits recombinant 3bHSD activity in vitro and endogenous 3bHSD activity in LNCaP and LAPC4 cells, including conversion ofandrogen receptor nuclear translocation, expression of androgen receptor-responsive genes, and xenograft growth in orchiectomized mice supplemented with DHEA. Abi also blocks conversion of D 5 -androstenediol to testosterone by 3bHSD. Abi inhibits 3bHSD1 and 3bHSD2 enzymatic activity in vitro; blocks conversion from DHEA to androstenedione and DHT with an IC 50 value of less than 1 mmol/L in CRPC cell lines; inhibits androgen receptor nuclear translocation; expression of TMPRSS2, prostate-specific antigen, and FKBP5; and decreases CRPC xenograft growth in DHEA-supplemented mice. Conclusions: We conclude that abi inhibits 3bHSD-mediated conversion of DHEA to active androgens in CRPC. This second mode of action might be exploited to reverse resistance to CYP17A1 inhibition at the standard abi dose by dose-escalation or simply by administration with food to increase drug exposure. Clin Cancer Res; 18(13);

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Epstein-Barr virus (EBV) establishes lifelong latent infection in humans and is associated with several lymphoid and epithelial cancers. In nasopharyngeal carcinoma (NPC), EBV expresses few viral proteins but elevated levels of Bam-HI A rightward transcripts (BARTs) RNA, which includes viral microRNAs and long non-coding RNAs (lncRNAs). BART lncRNAs localize within the nucleus of EBV-infected cells and knockdown of BART lncRNAs significantly affects the expression of genes associated with cell adhesion, oxidoreductase activity, inflammation, and immunity. Notably, downregulation of IKAROS family zinc finger 3 (IKZF3/Aiolos), which plays a role in lymphocyte development and cell attachment, occurred in NPC C666-1 cells following BART lncRNA-knockdown. Since Aiolos expression is normally restricted to lymphoid cells and rarely observed in epithelial cells, induction of Aiolos by BART lncRNA was confirmed by expressing the major BART lncRNA isoform, RPMS1, in EBV-positive and -negative cells. BART lncRNA associated with the CBP/p300 complex and RNA polymerase II (Pol II) in the nucleus, suggesting that BART lncRNAs may mediate epigenetic regulation of gene expression through interaction with the chromatin remodeling machinery. This contention is further supported by evidence that BART lncRNA appears to stall Pol II at the promoter region and may regulate IFNB1 and CXCL8 expression by inhibiting transcription by Pol II in NPC. We hypothesize that EBV BART lncRNA expression modulates host gene expression and maintains EBV latency by interfering with histone methylation and acetylation processes. Aberrant expression of affected host genes mediated by BART lncRNA may lead to immune evasion, progression, and metastasis of NPC.

Emerging evidence has suggested a close correlation between COVID-19 and neurodegenerative disorders. However, whether there exists a causal association and the effect direction remains unknown. To examine the causative role of COVID-19 in the risk of neurodegenerative disorders, we estimated their genetic correlation, and then conducted a two-sample Mendelian randomization analysis using summary statistics from genome-wide association studies of susceptibility, hospitalization, and severity of COVID-19, as well as six major neurodegenerative disorders including Alzheimer’s disease (AD), amyotrophic lateral sclerosis, frontotemporal dementia, Lewy body dementia, multiple sclerosis, and Parkinson’s disease. We identified a significant and positive genetic correlation between hospitalization of COVID-19 and AD (genetic correlation: 0.23, P = 8.36E–07). Meanwhile, hospitalization of COVID-19 was significantly associated with a higher risk of AD (OR: 1.02, 95% CI: 1.01–1.03, P: 1.19E–03). Consistently, susceptibility (OR: 1.05, 95% CI: 1.01–1.09, P: 9.30E–03) and severity (OR: 1.01, 95% CI: 1.00–1.02, P: 0.012) of COVID-19 were nominally associated with higher risk of AD. The results were robust under all sensitivity analyses. These results demonstrated that COVID-19 could increase the risk of AD. Future development of preventive or therapeutic interventions could attach importance to this to alleviate the complications of COVID-19.

Measurement of 16OHP and 11OHP along with 17OHP and 21dF by liquid chromatography/tandem mass spectrometry might comprise a biomarker panel to accurately diagnose all forms of 21OHD.