Androgen levels increase by intratumoral de novo steroidogenesis during progression of castration-resistant prostate cancer

HSD3B1, prostate cancer mortality and modifiable outcomes

Androgen receptor stimulation by testosterone and dihydrotestosterone is crucial for prostate cancer progression. Despite the initial effectiveness of androgen deprivation therapy (ADT), castration-resistant prostate cancer eventually develops in most men. A common germline missense-encoding polymorphism in HSD3B1 increases extra-gonadal androgen biosynthesis from adrenal precursors owing to increased availability of the encoded enzyme 3β-hydroxysteroid dehydrogenase 1 (3βHSD1) - hence, it is called the adrenal-permissive enzyme. This mechanism explains the more rapid progression to castration-resistant prostate cancer in men who inherit this allele than in men without it via sustained androgen receptor activation despite ADT. Multiple clinical studies, including data derived from prospective phase III studies, have linked adrenal-permissive allele inheritance to inferior clinical responses to ADT and increased mortality, but reversal is possible with upfront adrenal androgen blockade. The adrenal-permissive allele exhibits divergent frequencies across various groups worldwide, which could contribute to differences in clinical outcomes among these populations. Large-scale data from the Million Veteran Program have shown homozygous HSD3B1 adrenal-permissive allele inheritance to be an independent biomarker of prostate cancer-specific mortality. Together, these observations support the integration of HSD3B1 into germline testing and clinical trials as it might help to identify groups at increased likelihood of benefiting from early, intensified, AR-targeting interventions. Lastly, 3βHSD1 is a promising target for pharmacological inhibition, which enables new strategies for systemic prostate cancer therapy.

Metabolic adaptations in prostate cancer

Prostate cancer is one of the most commonly diagnosed cancers in men and is a major cause of cancer-related deaths worldwide. Among the molecular processes that contribute to this disease, the weight of metabolism has been placed under the limelight in recent years. Tumours exhibit metabolic adaptations to comply with their biosynthetic needs. However, metabolites also play an important role in supporting cell survival in challenging environments or remodelling the tumour microenvironment, thus being recognized as a hallmark in cancer. Prostate cancer is uniquely driven by androgen receptor signalling, and this knowledge has also influenced the paths of cancer metabolism research. This review provides a comprehensive perspective on the metabolic adaptations that support prostate cancer progression beyond androgen signalling, with a particular focus on tumour cell intrinsic and extrinsic pathways.

Androgen production, uptake, and conversion (APUC) genes define prostate cancer patients with distinct clinical outcomes

BACKGROUNDProstate cancer (PC) is driven by aberrant signaling of the androgen receptor (AR) or its ligands, and androgen deprivation therapies (ADTs) are a cornerstone of treatment. ADT responsiveness may be associated with germline changes in genes that regulate androgen production, uptake, and conversion (APUC).METHODSWe analyzed whole-exome sequencing (WES) and whole-transcriptome sequencing (WTS) data from prostate tissues (SU2C/PCF, TCGA, GETx). We also interrogated the Caris Precision Oncology Alliance (POA) DNA (592-gene/whole exome) and RNA (whole transcriptome) next-generation sequencing databases. Algorithm for Linking Activity Networks (ALAN) was used to quantify all pairwise gene-to-gene associations. Real-world overall survival was determined from insurance claims data using Kaplan-Meier estimates.RESULTSSix APUC genes (HSD3B1, HSD3B2, CYP3A43, CYP11A1, CYP11B1, CYP17A1) exhibited coalescent gene behavior in a cohort of metastatic tumors (n = 208). In the Caris POA dataset, the 6 APUC genes (APUC-6) exhibited robust clustering in primary prostate (n = 4,490) and metastatic (n = 2,593) biopsies. Surprisingly, tumors with elevated APUC-6 expression had statically lower expression of AR, AR-V7, and AR signaling scores, suggesting ligand-driven disease biology. APUC-6 genes instead associated with the expression of alternative steroid hormone receptors, ESR1/2 and PGR. We used RNA expression of AR or APUC-6 genes to define 2 subgroups of tumors with differential association with hallmark pathways and cell surface targets.CONCLUSIONSThe APUC-6-high/AR-low tumors represented a subgroup of patients with good clinical outcomes, in contrast with the AR-high or neuroendocrine PCs. Altogether, measuring the aggregate expression of APUC-6 genes in current genomic tests identifies PCs that are ligand (rather than AR) driven and require distinct therapeutic strategies.FUNDINGNCI/NIH 1R37CA288972-01, NCI Cancer Center Support P30 CA077598, DOD W81XWH-22-2-0025, R01 CA249279.

Loss of AR-regulated AFF3 contributes to prostate cancer progression and reduces ferroptosis sensitivity by downregulating ACSL4 based on single-cell sequencing analysis

Prostate cancer (PCa) is one of the most common cancers affecting the health of men worldwide. Castration-resistant prostate cancer (CRPC), the advanced and refractory phase of prostate cancer, has multiple mechanisms of resistance to androgen deprivation therapy (ADT) such as AR mutations, aberrant androgen synthase, and abnormal expression of AR-related genes. Based on the research of the AR pathway, new drugs for the treatment of CRPC have been developed in clinical practice, such as Abiraterone and enzalutamide. However, many areas in this pathway are still worth exploring. In this study, single-cell sequencing analysis was utilized to scrutinize significant genes in the androgen receptor (AR) pathway related to CRPC. Our analysis of single-cell sequencing combined with bulk-cell sequencing revealed a substantial downregulation of AR-regulated AFF3 in CRPC. Overexpression of AFF3 restricted the proliferation and migration of prostate cancer cells whilst also increasing their sensitivity towards enzalutamide, while knockdown of AFF3 had the opposite effect. To elucidate the mechanism of tumor inhibition by AFF3, we applied GSVA and GSEA to investigate the metabolic pathways related to AFF3 and revealed that AFF3 had an impact on fatty acids metabolism and ferroptosis through the regulation of ACSL4 protein expression. Based on correlation analysis and flow cytometry, we can speculate that AFF3 can impact the sensitivity of the CRPC cell lines to the ferroptosis inducer (RSL3) by regulating ACSL4. Therefore, our findings may provide new insights into the mechanisms of drug resistance in CRPC, and AFF3 may serve as a novel prognostic biomarker in prostate cancer.

Exploring androgen receptor signaling pathway in prostate cancer: A path to new discoveries

Androgen deprivation therapy has achieved significant success in treating prostate cancer through strategies centered on the androgen receptor. However, the emergence of castration-resistant prostate cancer highlights this therapy limitation, underscoring the need to elucidate the mechanisms of treatment resistance. This review aimed to focus on multifaceted resistance mechanisms, including androgen receptor overexpression, splice variants, missense mutations, the involvement of the glucocorticoid receptor, and alterations in coregulators and transcription factors, revealing their roles in castration-resistant prostate cancer progression. These mechanisms promote cell survival and proliferation, depending on the androgen receptor signaling pathway, leading to resistance to conventional therapies. Amplification and mutations in the androgen receptor gene facilitate selective adaptation in treatment-resistant cells, consequently diminishing therapeutic efficacy. Furthermore, the activation of glucocorticoid receptors and aberrant regulation of specific coregulators and transcription factors contribute to the activation of androgen receptor-independent signaling pathways, promoting cell survival and proliferation. These findings hold promise for identifying new targets for treating castration-resistant prostate cancer and developing personalized treatment strategies. The development of future therapies will hinge on precisely targeting the androgen receptor signaling pathway, necessitating a deeper understanding of the molecular targets unique to castration-resistant prostate cancer.

DHODH inhibition represents a therapeutic strategy and improves abiraterone treatment in castration-resistant prostate cancer

Castration-resistant prostate cancer (CRPC) is an aggressive disease with poor prognosis, and there is an urgent need for more effective therapeutic targets to address this challenge. Here, we showed that dihydroorotate dehydrogenase (DHODH), an enzyme crucial in the pyrimidine biosynthesis pathway, is a promising therapeutic target for CRPC. The transcript levels of DHODH were significantly elevated in prostate tumors and were negatively correlated with the prognosis of patients with prostate cancer. DHODH inhibition effectively suppressed CRPC progression by blocking cell cycle progression and inducing apoptosis. Notably, treatment with DHODH inhibitor BAY2402234 activated androgen biosynthesis signaling in CRPC cells. However, the combination treatment with BAY2402234 and abiraterone decreased intratumoral testosterone levels and induced apoptosis, which inhibited the growth of CWR22Rv1 xenograft tumors and patient-derived xenograft organoids. Taken together, these results establish DHODH as a key player in CRPC and as a potential therapeutic target for advanced prostate cancer.

ERBB3 Overexpression is Enriched in Diverse Patient Populations with Castration-sensitive Prostate Cancer and is Associated with a Unique AR Activity Signature

PURPOSE

Despite successful clinical management of castration-sensitive prostate cancer (CSPC), the 5-year survival rate for men with castration-resistant prostate cancer is only 32%. Combination treatment strategies to prevent disease recurrence are increasing, albeit in biomarker-unselected patients. Identifying a biomarker in CSPC to stratify patients who will progress on standard-of-care therapy could guide therapeutic strategies.

EXPERIMENTAL DESIGN

Targeted deep sequencing was performed for the University of Illinois (UI) cohort (n = 30), and immunostaining was performed on a patient tissue microarray (n = 149). Bioinformatic analyses identified pathways associated with biomarker overexpression (OE) in the UI cohort, consolidated RNA sequencing samples accessed from Database of Genotypes and Phenotypes (n = 664), and GSE209954 (n = 68). Neutralizing antibody patritumab and ectopic HER3 OE were utilized for functional mechanistic experiments.

RESULTS

We identified ERBB3 OE in diverse patient populations with CSPC, where it was associated with advanced disease at diagnosis. Bioinformatic analyses showed a positive correlation between ERBB3 expression and the androgen response pathway despite low dihydrotestosterone and stable expression of androgen receptor (AR) transcript in Black/African American men. At the protein level, HER3 expression was negatively correlated with intraprostatic androgen in Black/African American men. Mechanistically, HER3 promoted enzalutamide resistance in prostate cancer cell line models and HER3-targeted therapy resensitized therapy-resistant prostate cancer cell lines to enzalutamide.

CONCLUSIONS

In diverse patient populations with CSPC, ERBB3 OE was associated with high AR signaling despite low intraprostatic androgen. Mechanistic studies demonstrated a direct link between HER3 and enzalutamide resistance. ERBB3 OE as a biomarker could thus stratify patients for intensification of therapy in castration-sensitive disease, including targeting HER3 directly to improve sensitivity to AR-targeted therapies.

Pregnenolone sulfate induces transcriptional and immunoregulatory effects on T cells

Pregnenolone sulfate is a steroid metabolite of the steroidogenesis precursor, pregnenolone, with similar functional properties, including immunosuppression. We recently reported an elevation in serum levels of pregnenolone sulfate in children with malaria, contributing to an immunosuppressed state. Yet, the molecular mechanisms in which this steroid exerts its immunoregulatory functions are lacking. In this study, we examined the effects of pregnenolone sulfate on T cell viability, proliferation and transcriptome. We observed a pregnenolone sulfate dose-dependent induction of T cell death and reduction in proliferation. RNA sequencing analysis of pregnenolone sulfate-treated T cells for 2 and 24 h revealed the downregulation of pro-inflammatory genes and the upregulation of the steroid nuclear receptor superfamily, NR4A, as early-response genes. We also report a strong activation of the integrated stress response mediated by the upregulation of EIF2AK3. These results contribute to the knowledge on transcriptional regulation driving the immunoregulatory effects of pregnenolone sulfate on T cells.

Prostate cancer androgen biosynthesis relies solely on CYP17A1 downstream metabolites

Prostate cancer (PC) is dependent on androgen receptor (AR) activation by testosterone and 5α-dihydrotestosterone (DHT). Intratumoral androgen accumulation and activation despite systemic androgen deprivation therapy underlies the development of castration-resistant PC (CRPC), but the precise pathways involved remain controversial. Here we investigated the differential contributions of de novo androgen biosynthesis and androgen precursor conversion to androgen accumulation. Steroid flux analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed on (CR)PC cell lines and fresh patient PC tissue slices after incubation with classic and alternative biosynthesis intermediates, alongside quantitative PCR analysis for steroidogenic enzyme expression. Activity of CYP17A1 was undetectable in all PC cell lines and patient PC tissue slices. Instead, steroid flux analysis confirmed the generation of testosterone and DHT from adrenal precursors and reactivation of androgen metabolites. Precursor steroids upstream of DHEA were converted down the first steps of the alternative DHT biosynthesis pathway, but did not proceed through to active androgen generation. Comprehensive steroid flux analysis of (CR)PC cells provides strong evidence against intratumoral de novo androgen biosynthesis and demonstrates that androgen precursor steroids downstream of CYP17A1 activities constitute the major source of intracrine androgen generation.

Genomic and Evolutionary Characterization of Concurrent Intraductal Carcinoma and Adenocarcinoma of the Prostate

Intraductal carcinoma of the prostate (IDC-P) is a lethal prostate cancer subtype that generally coexists with invasive high-grade prostate acinar adenocarcinoma (PAC) but exhibits distinct biological features compared with concomitant adenocarcinoma. In this study, we performed whole-exome, RNA, and DNA-methylation sequencing of IDC-P, concurrent invasive high-grade PAC lesions, and adjacent normal prostate tissues isolated from 22 radical prostatectomy specimens. Three evolutionary patterns of concurrent IDC-P and PAC were identified: early divergent, late divergent, and clonally distant. In contrast to those with a late divergent evolutionary pattern, tumors with clonally distant and early divergent evolutionary patterns showed higher genomic, epigenomic, transcriptional, and pathologic heterogeneity between IDC-P and PAC. Compared with coexisting PAC, IDC-P displayed increased expression of adverse prognosis-associated genes. Survival analysis based on an independent cohort of 505 patients with metastatic prostate cancer revealed that IDC-P carriers with lower risk International Society of Urological Pathology (ISUP) grade 1-4 adenocarcinoma displayed a castration-resistant free survival as poor as those with the highest risk ISUP grade 5 tumors that lacked concurrent IDC-P. Furthermore, IDC-P exhibited robust cell-cycle progression and androgen receptor activities, characterized by an enrichment of cellular proliferation-associated master regulators and genes involved in intratumoral androgen biosynthesis. Overall, this study provides a molecular groundwork for the aggressive behavior of IDC-P and could help identify potential strategies to improve treatment of IDC-P.

SIGNIFICANCE

The genomic, transcriptomic, and epigenomic characterization of concurrent intraductal carcinoma and adenocarcinoma of the prostate deepens the biological understanding of this lethal disease and provides a genetic basis for developing targeted therapies.

PaSTe. Blockade of the Lipid Phenotype of Prostate Cancer as Metabolic Therapy: A Theoretical Proposal

BACKGROUND

Prostate cancer is the most frequently diagnosed malignancy in 112 countries and is the leading cause of death in eighteen. In addition to continuing research on prevention and early diagnosis, improving treatments and making them more affordable is imperative. In this sense, the therapeutic repurposing of low-cost and widely available drugs could reduce global mortality from this disease. The malignant metabolic phenotype is becoming increasingly important due to its therapeutic implications. Cancer generally is characterized by hyperactivation of glycolysis, glutaminolysis, and fatty acid synthesis. However, prostate cancer is particularly lipidic; it exhibits increased activity in the pathways for synthesizing fatty acids, cholesterol, and fatty acid oxidation (FAO).

OBJECTIVE

Based on a literature review, we propose the PaSTe regimen (Pantoprazole, Simvastatin, Trimetazidine) as a metabolic therapy for prostate cancer. Pantoprazole and simvastatin inhibit the enzymes fatty acid synthase (FASN) and 3-hydroxy-3-methylglutaryl- coenzyme A reductase (HMGCR), therefore, blocking the synthesis of fatty acids and cholesterol, respectively. In contrast, trimetazidine inhibits the enzyme 3-β-Ketoacyl- CoA thiolase (3-KAT), an enzyme that catalyzes the oxidation of fatty acids (FAO). It is known that the pharmacological or genetic depletion of any of these enzymes has antitumor effects in prostatic cancer.

RESULTS

Based on this information, we hypothesize that the PaSTe regimen will have increased antitumor effects and may impede the metabolic reprogramming shift. Existing knowledge shows that enzyme inhibition occurs at molar concentrations achieved in plasma at standard doses of these drugs.

CONCLUSION

We conclude that this regimen deserves to be preclinically evaluated because of its clinical potential for the treatment of prostate cancer.

The Role of Tumor Metabolic Reprogramming in Tumor Immunity

The occurrence and development of tumors require the metabolic reprogramming of cancer cells, namely the alteration of flux in an autonomous manner via various metabolic pathways to meet increased bioenergetic and biosynthetic demands. Tumor cells consume large quantities of nutrients and produce related metabolites via their metabolism; this leads to the remodeling of the tumor microenvironment (TME) to better support tumor growth. During TME remodeling, the immune cell metabolism and antitumor immune activity are affected. This further leads to the escape of tumor cells from immune surveillance and therefore to abnormal proliferation. This review summarizes the regulatory functions associated with the abnormal biosynthesis and activity of metabolic signaling molecules during the process of tumor metabolic reprogramming. In addition, we provide a comprehensive description of the competition between immune cells and tumor cells for nutrients in the TME, as well as the metabolites required for tumor metabolism, the metabolic signaling pathways involved, and the functionality of the immune cells. Finally, we summarize current research targeted at the development of tumor immunotherapy. We aim to provide new concepts for future investigations of the mechanisms underlying the metabolic reprogramming of tumors and explore the association of these mechanisms with tumor immunity.

Plasma Androstenedione Concentration Can Discriminate Frail versus Non-Frail Men with Prostate Cancer under Androgen Deprivation Therapy

BACKGROUND

Androgen deprivation therapy (ADT) is a mainstay of prostate cancer in both adjuvant and palliative settings. Since androgens are crucial for functional status and psychological functions, we evaluated whether blood testosterone, androstenedione, or DHEA concentrations were associated with functional status and psychological alterations in patients with localised (PCa) or metastatic prostate cancer (mPCa) receiving ADT with analogues of luteinising hormone-releasing hormone (LHRH).

METHODS

The five Fried criteria were considered to identify frailty syndrome. In addition, complementary evaluations were carried out to measure other variables of interest. Sleep quality was assessed using the Athens Insomnia Scale, cognitive functions were assessed using the Mini-Mental State Examination, and symptoms of depression were measured using the Yesavage Geriatric Depression Scale. Logistic regression analysis was performed to determine if the androgens level could be related to frailty syndrome, sleep impairment, depressive symptoms, and cognitive functions.

RESULTS

The results of the multivariate analyses show that high concentrations of androstenedione were significantly associated with frailty syndrome in both groups (p = 0.018; odds ratio = 4.66, 95% confidence interval [1.30-16.6]). There were significant relationships between frailty syndrome and the systemic concentration of androstenedione (p = 0.01), but not the concentration of testosterone (p = 0.60) or DHEA (p = 0.42). In addition, the results of the non-parametric tests show significant results between a decreased gait speed in the two groups (metastatic and localised) and the concentration of androstenedione (p = 0.015). High androstenedione levels were associated with a slow walking speed in the mCaP group (p = 0.016), while high testosterone levels were associated with a better walking speed in the localised CaP group (p = 0.03). For the concentration of androstenedione in plasma, the area under the curve was 0.72, with a 95% CI of 0.55-0.88 with acceptable values, and with a cut-off point of 4.51 pg/mL, a sensitivity of 82.9%, and specificity of 53.8%. No relationships between the concentration of androgens in plasma and sleep quality, cognitive functions, or symptoms of depression suggest that the changes were specific to frailty syndrome.

CONCLUSIONS

Further research into the role of androstenedione should be evaluated in follow-up studies in order to recommend its use as a suitable biomarker of frailty syndrome in prostate cancer patients.

CYP11A1 silencing suppresses HMGCR expression via cholesterol accumulation and sensitizes CRPC cell line DU-145 to atorvastatin

Statins, which are cholesterol synthesis inhibitors, are well-known therapeutics for dyslipidemia; however, some studies have anticipated their use as anticancer agents. However, epithelial cancer cells show strong resistance to statins through an increased expression of HMG-CoA reductase (HMGCR), an inhibitory target of statins. Castration-resistant prostate cancer (CRPC) cells synthesize androgens from cholesterol on their own. We performed suppression of CYP11A1, a rate-limiting enzyme in androgen synthesis from cholesterol, using siRNA or inhibitors, to examine the effect of steroidogenesis inhibition on statin sensitivity in CRPC cells. Here, we suggested that CYP11A1 silencing sensitized the statin-resistant CRPC cell line DU-145 to atorvastatin via HMGCR downregulation by an increase in intracellular free cholesterol. We further demonstrated that CYP11A1 silencing induced epithelial-mesenchymal transition, which converted DU-145 cells into a statin-sensitive phenotype. This suggests that concomitant use of CYP11A1 inhibitors could be an effective approach for overcoming statin resistance in CRPC. Moreover, we showed that ketoconazole, a CYP11A1 inhibitor, sensitized DU-145 cells to atorvastatin, although not all the molecular events observed in CYP11A1 silencing were reproducible. Although further studies are necessary to clarify the detailed mechanisms, ketoconazole may be effective as a concomitant drug that potentiates the anticancer effect of atorvastatin.

Neoadjuvant Cabazitaxel plus Abiraterone/Leuprolide Acetate in Patients with High-Risk Prostate Cancer: ACDC-RP Phase II Trial

PURPOSE

Early treatment intensification with neoadjuvant therapy may improve outcomes in patients with high-risk, localized prostate cancer treated with radical prostatectomy. Our objective was to compare pathologic, oncologic, and safety outcomes of neoadjuvant abiraterone acetate plus leuprolide acetate with or without cabazitaxel prior to radical prostatectomy in patients with localized, high-risk prostate cancer.

PATIENTS AND METHODS

This open-label, multicenter, phase II trial randomized men with clinically localized, D'Amico high-risk prostate cancer to neoadjuvant abiraterone acetate (1,000 mg/day) and leuprolide acetate (22.5 mg every 3 months) with or without cabazitaxel (25 mg/m2) prior to radical prostatectomy. The primary outcome was pathologic complete response (pCR) or minimal residual disease (MRD). Secondary outcomes included surgical margins, lymph node involvement, pathologic stage, 12-month biochemical relapse-free survival (BRFS) rates, and safety profile.

RESULTS

The per-protocol population consisted of 70 patients [cabazitaxel arm (Arm A): 37, no cabazitaxel arm (Arm B): 33]. Median patient age and prostate-specific antigen levels were 63.5 years [interquartile range (IQR), 58.0-68.0] and 21.9 ng/mL (IQR, 14.6-42.8), respectively. pCR/MRD occurred in 16 (43.2%) versus 15 patients (45.5%) in arms A and B, respectively (P = 0.85). pCR occurred in two (5.4%) versus three patients (9.1%) in arms A and B, respectively (P = 0.66). Patients with ≤ 25% total biopsy cores positive had increased odds of pCR/MRD (P = 0.04). Patients with pCR/MRD had superior 12-month BRFS rates (96.0% vs. 62.0%, P = 0.03). Grade 3+ adverse events occurred in 42.5% and 23.7% of patients in arms A and B, respectively (P = 0.078).

CONCLUSIONS

Neoadjuvant cabazitaxel addition to abiraterone acetate/leuprolide acetate prior to radical prostatectomy did not improve pCR/MRD in clinically localized, high-risk prostate cancer.

Aldo-Keto Reductase 1C3 Inhibitor Prodrug Improves Pharmacokinetic Profile and Demonstrates In Vivo Efficacy in a Prostate Cancer Xenograft Model

Aldo-keto reductase 1C3 (AKR1C3) is overexpressed in castration-resistant prostate cancer where it acts to drive proliferation and aggressiveness by producing androgens. The reductive action of the enzyme leads to chemoresistance development against various clinical antineoplastics across a range of cancers. Herein, we report the continued optimization of selective AKR1C3 inhibitors and the identification of 5r, a potent AKR1C3 inhibitor (IC50 = 51 nM) with >1216-fold selectivity for AKR1C3 over closely related isoforms. Due to the cognizance of the poor pharmacokinetics associated with free carboxylic acids, a methyl ester prodrug strategy was pursued. The prodrug 4r was converted to free acid 5r in vitro in mouse plasma and in vivo. The in vivo pharmacokinetic evaluation revealed an increase in systemic exposure and increased the maximum 5r concentration compared to direct administration of the free acid. The prodrug 4r demonstrated a dose-dependent effect to reduce the tumor volume of 22Rv1 prostate cancer xenografts without observed toxicity.

Histone H2A Lys130 acetylation epigenetically regulates androgen production in prostate cancer

The testicular androgen biosynthesis is well understood, however, how cancer cells gauge dwindling androgen to dexterously initiate its de novo synthesis remained elusive. We uncover dual-phosphorylated form of sterol regulatory element-binding protein 1 (SREBF1), pY673/951-SREBF1 that acts as an androgen sensor, and dissociates from androgen receptor (AR) in androgen deficient environment, followed by nuclear translocation. SREBF1 recruits KAT2A/GCN5 to deposit epigenetic marks, histone H2A Lys130-acetylation (H2A-K130ac) in SREBF1, reigniting de novo lipogenesis & steroidogenesis. Androgen prevents SREBF1 nuclear translocation, promoting T cell exhaustion. Nuclear SREBF1 and H2A-K130ac levels are significantly increased and directly correlated with late-stage prostate cancer, reversal of which sensitizes castration-resistant prostate cancer (CRPC) to androgen synthesis inhibitor, Abiraterone. Further, we identify a distinct CRPC lipid signature resembling lipid profile of prostate cancer in African American (AA) men. Overall, pY-SREBF1/H2A-K130ac signaling explains cancer sex bias and reveal synchronous inhibition of KAT2A and Tyr-kinases as an effective therapeutic strategy.

Identification of androgen response-related lncRNAs in prostate cancer

BACKGROUND

Long noncoding RNAs (lncRNAs) are RNA molecules with over 200 nucleotides that do not code for proteins, but are known to be widely expressed and have key roles in gene regulation and cellular functions. They are also found to be involved in the onset and development of various cancers, including prostate cancer (PCa). Since PCa are commonly driven by androgen regulated signaling, mainly stimulated pathways, identification and determining the influence of lncRNAs in androgen response is useful and necessary. LncRNAs regulated by the androgen receptor (AR) can serve as potential biomarkers for PCa. In the present study, gene expression data analysis were performed to distinguish lncRNAs related to the androgen response pathway.

METHODS AND RESULTS

We used publicly available RNA-sequencing and ChIP-seq data to identify lncRNAs that are associated with the androgen response pathway. Using Universal Correlation Coefficient (UCC) and Pearson Correlation Coefficient (PCC) analyses, we found 15 lncRNAs that have (a) highly correlated expression with androgen response genes in PCa and are (b) differentially expressed in the setting of treatment with an androgen agonist as well as antagonist compared to controls. Using publicly available ChIP-seq data, we investigated the role of androgen/AR axis in regulating expression of these lncRNAs. We observed AR binding in the promoter regions of 5 lncRNAs (MIR99AHG, DUBR, DRAIC, PVT1, and COLCA1), showing the direct influence of AR on their expression and highlighting their association with the androgen response pathway.

CONCLUSION

By utilizing publicly available multiomics data and by employing in silico methods, we identified five candidate lncRNAs that are involved in the androgen response pathway. These lncRNAs should be investigated as potential biomarkers for PCa.

Epigenetic mechanism of therapeutic resistance and potential of epigenetic therapeutics in chemorefractory prostate cancer

Prostate cancer is the second leading cause of cancer death among men in the United States. Depending upon the histopathological subtypes of prostate cancers, various therapeutic options, such as androgen deprivation therapy (ADT), androgen receptor signaling inhibitors (ARSI), immunotherapy, and chemotherapy, are available to treat prostate cancer. While these therapeutics are effective in the initial stages during treatments, the tumors subsequently develop resistance to these therapies. Despite all the progress made so far, therapeutic resistance remains a major challenge in the treatment of prostate cancer. Although various mechanisms have been reported for the resistance development in prostate cancer, altered expression of genes either directly or indirectly involved in drug response pathways is a common event. In addition to the genetic basis of gene regulation such as mutations and gene amplifications, epigenetic alterations involved in the aberrant expression of genes have frequently been shown to be associated not only with cancer initiation and progression but also with therapeutic resistance development. There are several review articles compiling reports on genetic mechanisms involved in therapeutic resistance in prostate cancer. However, epigenetic mechanisms for the therapeutic resistance development in prostate cancer have not yet been summarized in a review article. Therefore, the objective of this article is to compile various reports and provide a comprehensive review of the epigenetic aberrations, and aberrant expression of genes by epigenetic mechanisms involved in CRPCs and therapeutic resistance development in prostate cancer. Additionally, the potential of epigenetic-based therapeutics in the treatment of chemorefractory prostate cancer as evidenced by clinical trials has also been discussed.

A Phase II Trial of Abiraterone With Dutasteride for Second-Generation Antiandrogen- and Chemotherapy-Naïve Patients With Castration-Resistant Prostate Cancer

The development of a novel therapy to overcome primary and acquired resistance to abiraterone is an unmet need. This study aimed to evaluate the efficacy and safety of adding 5α-reductase inhibitor dutasteride to abiraterone, explore proof of concept, and identify candidates suitable for combination therapy. This phase II, single-arm, and open-label study enrolled second-generation antiandrogen- and chemotherapy-naïve patients with castration-resistant prostate cancer. Patients received abiraterone and prednisolone for 4 weeks, followed by adding dutasteride. The primary end point was a 50% prostate-specific antigen response rate. Serum concentrations of abiraterone and its metabolites as well as HSD3B1 and SRD5A2 genotypes were measured. The association between drug metabolism and genotypes and their impact on the efficacy of combination therapy were assessed. Among 21 patients, 18 (85.7%) achieved ≥50% PSA reduction. Median time to treatment failure was not reached during the median follow-up of 15.4 months. No patients experienced grade ≥3 adverse events. Although dutasteride reduced serum 3-keto-5α-abiraterone concentrations, higher serum 3-keto-5α-abiraterone concentrations on combination therapy were associated with a shorter time to treatment failure. HSD3B1 and SRD5A2 genotypes were associated with serum Δ4-abiraterone and 3-keto-5α-abiraterone concentrations before adding dutasteride, respectively. Time to treatment failure was longer in patients with homozygous wild-type HSD3B1, but comparable between those with the SRD5A2 genotype. The promising outcomes of this study warrant further investigation of combination therapy in a randomized trial. Stratification by HSD3B1 and SRD5A2 genetic profiles might identify patients suitable for combination therapy.

Pseurotin A Validation as a Metastatic Castration-Resistant Prostate Cancer Recurrence-Suppressing Lead via PCSK9-LDLR Axis Modulation

Metastatic castration-resistant prostate cancer (mCRPC) cells can de novo biosynthesize their own cholesterol and overexpress proprotein convertase subtilisin/kexin type 9 (PCSK9). PCSK9 proved to contribute to mCRPC cell motility since PCSK9 knockdown (KD) in mCRPC CWR-R1ca cells led to notable reductions in cell migration and colony formation. Human tissue microarray results proved a higher immunohistoscore in patients ≥ 65 years old, and PCSK9 proved to be expressed higher at an early Gleason score of ≤7. The fermentation product pseurotin A (PS) suppressed PCSK9 expression, protein-protein interactions with LDLR, and breast and prostate cancer recurrences. PS suppressed migration and colony formation of the CWR-R1ca cells. The progression and metastasis of the CWR-R1ca-Luc cells subcutaneously (sc) xenografted into male nude mice fed a high-fat diet (HFD, 11% fat content) showed nearly 2-fold tumor volume, metastasis, serum cholesterol, low-density lipoprotein cholesterol (LDL-C), prostate-specific antigen (PSA), and PCSK9 levels versus mice fed a regular chow diet. Daily oral PS 10 mg/kg treatments prevented the locoregional and distant tumor recurrence of CWR-R1ca-Luc engrafted into nude mice after primary tumor surgical excision. PS-treated mice showed a significant reduction in serum cholesterol, LDL-C, PCSK9, and PSA levels. These results comprehensively validate PS as an mCRPC recurrence-suppressive lead by modulating the PCSK9-LDLR axis.

Antiandrogen-Equipped Histone Deacetylase Inhibitors Selectively Inhibit Androgen Receptor (AR) and AR-Splice Variant (AR-SV) in Castration-Resistant Prostate Cancer (CRPC)

BACKGROUND

Epigenetic modification influences androgen receptor (AR) activation, often resulting in prostate cancer (PCa) development and progression. Silencing histone-modifying enzymes (histone deacetylases-HDACs) either genetically or pharmacologically suppresses PCa proliferation in preclinical models of PCa; however, results from clinical studies were not encouraging. Similarly, PCa patients eventually become resistant to androgen ablation therapy (ADT). Our goal is to develop dual-acting small molecules comprising antiandrogen and HDAC-inhibiting moieties that may overcome the resistance of ADT and effectively suppress the growth of castration-resistant prostate cancer (CRPC).

METHODS

Several rationally designed antiandrogen-equipped HDAC inhibitors (HDACi) were synthesized, and their efficacy on CRPC growth was examined both in vitro and in vivo.

RESULTS

While screening our newly developed small molecules, we observed that SBI-46 significantly inhibited the proliferation of AR+ CRPC cells but not AR- CRPC and normal immortalized prostate epithelial cells (RWPE1) or normal kidney cells (HEK-293 and VERO). Molecular analysis confirmed that SBI-46 downregulated the expressions of both AR+ and AR-splice variants (AR-SVs) in CRPC cells. Further studies revealed the downregulation of AR downstream (PSA) events in CRPC cells. The oral administration of SBI-46 abrogated the growth of C4-2B and 22Rv1 CRPC xenograft tumors that express AR or both AR and AR-SV in xenotransplanted nude mice models. Further, immunohistochemical analysis confirmed that SBI-46 inhibits AR signaling in xenografted tumor tissues.

CONCLUSION

These results demonstrate that SBI-46 is a potent agent that inhibits preclinical models of CRPC by downregulating the expressions of both AR and AR-SV. Furthermore, these results suggest that SBI-46 may be a potent compound for treating CRPC.

Prospective role of 3βHSD1 in prostate cancer precision medicine

BACKGROUND

Prostate cancer is addicted to androgens. The steroidogenic enzyme 3β-hydroxysteroid dehydrogenase 1 (3βHSD1) recognizes pregnenolone, dehydroepiandrosterone (DHEA), and steroidal medicine abiraterone as substrates to accelerate disease progression.

METHODS

References for this review were identified through searches of PubMed with the search terms "prostate cancer", "HSD3B1", and "3bHSD1" from 1990 until June, 2022.

RESULTS

Genotype of 3βHSD1 has been reported to correlate with tumor aggressiveness of advanced prostate cancer in multiple clinical scenarios. The ethnic differences and limitations of using 3βHSD1 genotype as a prognostic biomarker have been discussed here. The activity of 3βHSD1 increases in patients treated with abiraterone and enzalutamide, giving rise to treatment resistance. Further elucidation of 3βHSD1 regulatory mechanisms will shed light on more approaches for disease intervention. We also review the recent advance on 3βHSD1 inhibitors and targeting 3βHSD1 for prostate cancer management. Novel 3βHSD1 inhibitors will be needed to provide additional options for prostate cancer management.

CONCLUSION

3βHSD1 is both a predictive biomarker and a promising therapeutic target for prostate cancer.

Preclinical models of prostate cancer - modelling androgen dependency and castration resistance in vitro, ex vivo and in vivo

Prostate cancer is well known to be dependent on the androgen receptor (AR) for growth and survival. Thus, AR is the main pharmacological target to treat this disease. However, after an initially positive response to AR-targeting therapies, prostate cancer will eventually evolve to castration-resistant prostate cancer, which is often lethal. Tumour growth was initially thought to become androgen-independent following treatments; however, results from molecular studies have shown that most resistance mechanisms involve the reactivation of AR. Consequently, tumour cells become resistant to castration - the blockade of testicular androgens - and not independent of AR per se. However, confusion still remains on how to properly define preclinical models of prostate cancer, including cell lines. Most cell lines were isolated from patients for cell culture after evolution of the tumour to castration-resistant prostate cancer, but not all of these cell lines are described as castration resistant. Moreover, castration refers to the blockade of testosterone production by the testes; thus, even the concept of "castration" in vitro is questionable. To ensure maximal transfer of knowledge from scientific research to the clinic, understanding the limitations and advantages of preclinical models, as well as how these models recapitulate cancer cell androgen dependency and can be used to study castration resistance mechanisms, is essential.

Novel inhibition of AKR1C3 and androgen receptor axis by PTUPB synergizes enzalutamide treatment in advanced prostate cancer

Castration-resistant prostate cancer (CRPC) is the main driving force of mortality in prostate cancer patients. Among the parameters contributing to the progression of CRPC and treatment failure, elevation of the steroidogenic enzyme AKR1C3 and androgen receptor variant 7 (AR-V7) are frequently reported. The AKR1C3/AR-V7 complex has been recognized as a major driver for drug resistance in advanced prostate cancer. Herein we report that the level of AKR1C3 is reciprocally regulated by the full-length androgen receptor (AR-FL) through binding to the distal enhancer region of the AKR1C3 gene. A novel function of PTUPB in AKR1C3 inhibition was discovered and PTUPB showed more effectiveness than indomethacin and celecoxib in suppressing AKR1C3 activity and CRPC cell growth. PTUPB synergizes with enzalutamide treatment in tumor suppression and gene signature regulation. Combination treatments with PTUPB and enzalutamide provide benefits by blocking AR/AR-V7 signaling, which inhibits the growth of castration relapsed VCaP xenograft tumors and patient-derived xenograft organoids. Targeting of the ARK1C3/AR/AR-V7 axis with PTUPB and enzalutamide may overcome drug resistance to AR signaling inhibitors in advanced prostate cancer.

Dissecting the effects of androgen deprivation therapy on cadherin switching in advanced prostate cancer: A molecular perspective

Prostate cancer is one of the most often diagnosed malignancies in males and its prevalence is rising in both developed and developing countries. Androgen deprivation therapy has been used as a standard treatment approach for advanced prostate cancer for more than 80 years. The primary aim of androgen deprivation therapy is to decrease circulatory androgen and block androgen signaling. Although a partly remediation is accomplished at the beginning of treatment, some cell populations become refractory to androgen deprivation therapy and continue to metastasize. Recent evidences suggest that androgen deprivation therapy may cause cadherin switching, from E-cadherin to N-cadherin, which is the hallmark of epithelial-mesenchymal transition. Diverse direct and indirect mechanisms are involved in this switching and consequently, the cadherin pool changes from E-cadherin to N-cadherin in the epithelial cells. Since E-cadherin represses invasive and migrative behaviors of the tumor cells, the loss of E-cadherin disrupts epithelial tissue structure leading to the release of tumor cells into surrounding tissues and circulation. In this study, we review the androgen deprivation therapy-dependent cadherin switching in advanced prostate cancer with emphasis on its molecular basis especially the transcriptional factors regulated through TFG-β pathway.

Relationship between 4-Hydroxynonenal (4-HNE) as Systemic Biomarker of Lipid Peroxidation and Metabolomic Profiling of Patients with Prostate Cancer

An oxidative degradation product of the polyunsaturated fatty acids, 4-hydroxynonenal (4-HNE), is of particular interest in cancer research due to its concentration-dependent pleiotropic activities affecting cellular antioxidants, metabolism, and growth control. Although an increase in oxidative stress and lipid peroxidation was already associated with prostate cancer progression a few decades ago, the knowledge of the involvement of 4-HNE in prostate cancer tumorigenesis is limited. This study investigated the appearance of 4-HNE-protein adducts in prostate cancer tissue by immunohistochemistry using a genuine 4-HNE monoclonal antibody. Plasma samples of the same patients and samples of the healthy controls were also analyzed for the presence of 4-HNE-protein adducts, followed by metabolic profiling using LC-ESI-QTOF-MS and GC-EI-Q-MS. Finally, the analysis of the metabolic pathways affected by 4-HNE was performed. The obtained results revealed the absence of 4-HNE-protein adducts in prostate carcinoma tissue but increased 4-HNE-protein levels in the plasma of these patients. Metabolomics revealed a positive association of different long-chain and medium-chain fatty acids with the presence of prostate cancer. Furthermore, while linoleic acid positively correlated with the levels of 4-HNE-protein adducts in the blood of healthy men, no correlation was obtained for cancer patients indicating altered lipid metabolism in this case. The metabolic pathway of unsaturated fatty acids biosynthesis emerged as significantly affected by 4-HNE. Overall, this is the first study linking 4-HNE adduction to plasma proteins with specific alterations in the plasma metabolome of prostate cancer patients. This study revealed that increased 4-HNE plasma protein adducts could modulate the unsaturated fatty acids biosynthesis pathway. It is yet to be determined if this is a direct result of 4-HNE or whether they are produced by the same underlying mechanisms. Further mechanistic studies are needed to grasp the biological significance of the observed changes in prostate cancer tumorigenesis.

Novel biomarkers predict prognosis and drug-induced neuroendocrine differentiation in patients with prostate cancer

Background

A huge focus is being placed on the development of novel signatures in the form of new combinatorial regimens to distinguish the neuroendocrine (NE) characteristics from castration resistant prostate cancer (CRPC) timely and accurately, as well as predict the disease-free survival (DFS) and progression-free survival (PFS) of prostate cancer (PCa) patients.

Methods

Single cell data of 4 normal samples, 3 CRPC samples and 3 CRPC-NE samples were obtained from GEO database, and CellChatDB was used for potential intercellular communication, Secondly, using the "limma" package (v3.52.0), we obtained the differential expressed genes between CRPC and CRPC-NE both in single-cell RNA seq and bulk RNA seq samples, and discovered 12 differential genes characterized by CRPC-NE. Then, on the one hand, the diagnosis model of CRPC-NE is developed by random forest algorithm and artificial neural network (ANN) through Cbioportal database; On the other hand, using the data in Cbioportal and GEO database, the DFS and PFS prognostic model of PCa was established and verified through univariate Cox analysis, least absolute shrinkage and selection operator (Lasso) regression and multivariate Cox regression in R software. Finally, somatic mutation and immune infiltration were also discussed.

Results

Our research shows that there exists specific intercellular communication in classified clusters. Secondly, a CRPC-NE diagnostic model of six genes (HMGN2, MLLT11, SOX4, PCSK1N, RGS16 and PTMA) has been established and verified, the area under the ROC curve (AUC) is as high as 0.952 (95% CI: 0.882-0.994). The mutation landscape shows that these six genes are rarely mutated in the CRPC and NEPC samples. In addition, NE-DFS signature (STMN1 and PCSK1N) and NE-PFS signature (STMN1, UBE2S and HMGN2) are good predictors of DFS and PFS in PCa patients and better than other clinical features. Lastly, the infiltration levels of plasma cells, T cells CD4 naive, Eosinophils and Monocytes were significantly different between the CRPC and NEPC groups.

Conclusions

This study revealed the heterogeneity between CRPC and CRPC-NE from different perspectives, and developed a reliable diagnostic model of CRPC-NE and robust prognostic models for PCa.

Preclinical and Clinical Research Models of Prostate Cancer: A Brief Overview

The incidence and mortality from prostate cancer (PCa) are on the rise which poses a major public health concern worldwide. In this narrative review, we have summarized the characteristics of major in vitro and in vivo PCa models including their utility in developing treatment strategies. Androgens, particularly, testosterone and dihydrotestosterone (DHT) activate the androgen receptor (AR) signaling pathway that facilitates the development and progression of castration resistant PCa. Several enzymes namely, CYP17A1, HSD17B, and SRD5A are essential to furnishing DHT from dehydroepiandrosterone in the classical pathway while DHT is formed from androstanediol in the backdoor pathway. The advancement in delineating the molecular heterogeneity of PCa has been possible through the development of several in vitro and in vivo research models. Generally, tissue culture models are advantageous to understand PCa biology and investigate the efficacy and toxicity of novel agents; nevertheless, animal models are indispensable to studying the PCa etiology and treatment since they can simulate the tumor microenvironment that plays a central role in initiation and progression of the disease. Moreover, the availability of several genetically engineered mouse models has made it possible to study the metastasis process. However, the conventional models are not devoid of limitations. For example, the lack of heterogeneity in tissue culture models and the variation of metastatic characteristics in xenograft models are obviously challenging. Additionally, due to the racial and ethnic disparities in PCa pathophysiology, a new model that can represent PCa encompassing different ethnicities is urgently needed. New models should continue to evolve to address the genetic and molecular complexities as well as to further elucidate the finer details of the steroidogenic pathway associated with PCa.

Extracellular vesicles from biological fluids as potential markers in castration resistant prostate cancer

PURPOSE

Extracellular vesicles (EV) secreted from cancer cells are present in various biological fluids, carrying distinctly different cellular components compared to normal cells, and have great potential to be used as markers for disease initiation, progression, and response to treatment. This under-utilised tool provides insights into a better understanding of prostate cancer.

METHODS

EV from serum and urine of healthy men and castration-resistant prostate cancer (CRPC) patients were isolated and characterised by transmission electron microscopy, particle size analysis, and western blot. Proteomic and cholesterol liquid chromatography-mass spectrometry (LC-MS) analyses were conducted.

RESULTS

There was a successful enrichment of small EV/exosomes isolated from serum and urine. EV derived from biological fluids of CRPC patients had significant differences in composition when compared with those from healthy controls. Analysis of matched serum and urine samples from six prostate cancer patients revealed specific EV proteins common in both types of biological fluid for each patient.

CONCLUSION

Some of the EV proteins identified from our analyses have potential to be used as CRPC markers. These markers may depict a pattern in cancer progression through non-invasive sample collection.

Cholelithiasis increased prostate cancer risk: evidence from a case-control study and a meta-analysis

Introduction

Cholelithiasis represents a known risk factor for digestive system neoplasm. Few studies reported the association between cholelithiasis and the risk of prostate cancer (PCa), and the results were controversial.

Methods

We reviewed the medical records of the Second Affiliated Hospital of Chongqing Medical University Hospital to perform a retrospective matched case–control study, which included newly diagnosed 221 PCa patients and 219 matched controls. Logistic regression was applied to compare cholelithiasis exposure and adjusted for confounding factors. Additionally, we conducted a meta-analysis pooling this and published studies further to evaluate the association between cholelithiasis and PCa risk. Related ratio (RR) and 95% confidence interval (95%CI) were used to assess the strength of associations.

Results

Our case–control study showed that cholelithiasis was associated with a higher incidence of PCa (OR = 1.87, 95% CI: 1.06–3.31) after multivariable adjustment for covariates. The incidence of PCa was increased in patients with gallstones but not cholecystectomy. 7 studies involving 80,403 individuals were included in the meta-analysis. Similarly, the results demonstrated that cholelithiasis was associated with an increased risk of PCa (RR = 1.35, 95%CI: 1.17–1.56) with moderate-quality evidence. Cholelithiasis patients with low BMI increased the PCa incidence. Moreover, Subgroup analysis based on region showed that cholelithiasis was associated with PCa in Europe (RR = 1.24, 95%CI 1.03–1.51) and Asia (RR = 1.32, 95%CI 1.24–1.41).

Conclusions

The results suggested an association between cholelithiasis and the risk of PCa. There was no significant relationship between cholecystectomy therapy and PCa risk. Further cohort studies should be conducted to demonstrate the results better.

Chemical synthesis of fluorinated and iodinated 17β-HSD3 inhibitors and evaluation for imaging prostate cancer tumors and tissue biodistribution

Prostate cancer is the most common cancer among men and the development of new therapeutic agents is needed for its treatment and/or diagnosis. 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) is involved in the production of androgens, which stimulates the proliferation of prostate cancer cells. Piperazinomethyl-androsterone sulfonamide derivatives were developed as 17β-HSD3 inhibitors and the concentration of a representative sulfonamide derivative (compound 1) was found to accumulate in prostate tumor tissues relatively to plasma in a mouse xenograft experiment. This finding gives us the opportunity to specifically target the prostate cancer tumors through the development of a radiolabelled version of compound 1 toward targeted molecular radiotherapy or radioimaging diagnosis. The chemical synthesis of fluorinated and iodinated analogs of compound 1 was achieved, leading to a series of compounds with similar levels of inhibition as the initial candidate. From 17β-HSD3 inhibition activity, molecular modeling and mouse plasma-concentration studies, the most promising compound of this series was selected, its ¹⁸F-radiolabelled version (¹⁸F-3) synthesized, and imaging/biodistribution studies engaged. When injected in mice, however, ¹⁸F-3 uptake in the target tissues (LNCaP[17β-HSD3] tumors and testicles) was not sufficient to allow their visualization by positron emission tomography. Plasma concentration values of compounds 3-8 administered orally, however, showed that the para-iodo compound 7 is the most metabolically stable and could therefore be an interesting alternative for radiolabelling and radiotreatment.

Antitumor effects of pyrrole-imidazole polyamide modified with alkylating agent on prostate cancer cells

Androgens and androgen receptor (AR) have a central role in prostate cancer progression by regulating its downstream signaling. Although androgen depletion therapy (ADT) is the primary treatment for most prostate cancers, they acquires resistance to ADT and become castration resistant prostate cancers (CRPC). AR complex formation with multiple transcription factors is important for enhancer activity and transcriptional regulation, which can contribute to cancer progression and resistance to ADT. We previously demonstrated that OCT1 collaborates with AR in prostate cancer, and that a pyrrole-imidazole (PI) polyamide (PIP) targeting OCT1 inhibits cell and castration-resistant tumor growth (Obinata D et al. Oncogene 2016). PIP can bind to DNA non-covalently without a drug delivery system unlike most DNA targeted therapeutics. In the present study, we developed a PIP modified with a DNA alkylating agent, chlorambucil (ChB) (OCT1-PIP-ChB). Then its effect on the growth of prostate cancer LNCaP, 22Rv1, and PC3 cells, pancreatic cancer BxPC3 cells, and colon cancer HCT116 cells, as well as non-cancerous MCF-10A epithelial cells, were analyzed. It was shown that the IC50s of OCT1-PIP-ChB for 22Rv1 and LNCaP were markedly lower compared to other cells, including non-cancerous MCF-10A cells. Comprehensive gene expression analysis of CRPC model 22Rv1 cells treated with IC50 concentrations of OCT1-PIP-ChB revealed that the gene group involved in DNA double-strand break repair was the most enriched among gene sets repressed by OCT1-PIP-ChB treatment. Importantly, in vivo study using 22Rv1 xenografts, we showed that OCT1-PIP-ChB significantly reduced tumor growth compared to the control group without showing obvious adverse effects. Thus, the PIP combined with ChB can exert a significant inhibitory effect on prostate cancer cell proliferation and castration-resistant tumor growth, suggesting a potential role as a therapeutic agent.

Targeting signaling pathways in prostate cancer: mechanisms and clinical trials

Prostate cancer (PCa) affects millions of men globally. Due to advances in understanding genomic landscapes and biological functions, the treatment of PCa continues to improve. Recently, various new classes of agents, which include next-generation androgen receptor (AR) signaling inhibitors (abiraterone, enzalutamide, apalutamide, and darolutamide), bone-targeting agents (radium-223 chloride, zoledronic acid), and poly(ADP-ribose) polymerase (PARP) inhibitors (olaparib, rucaparib, and talazoparib) have been developed to treat PCa. Agents targeting other signaling pathways, including cyclin-dependent kinase (CDK)4/6, Ak strain transforming (AKT), wingless-type protein (WNT), and epigenetic marks, have successively entered clinical trials. Furthermore, prostate-specific membrane antigen (PSMA) targeting agents such as ¹⁷⁷Lu-PSMA-617 are promising theranostics that could improve both diagnostic accuracy and therapeutic efficacy. Advanced clinical studies with immune checkpoint inhibitors (ICIs) have shown limited benefits in PCa, whereas subgroups of PCa with mismatch repair (MMR) or CDK12 inactivation may benefit from ICIs treatment. In this review, we summarized the targeted agents of PCa in clinical trials and their underlying mechanisms, and further discussed their limitations and future directions.

A Tale of Two Cancers: A Current Concise Overview of Breast and Prostate Cancer

Cancer is a global issue, and it is expected to have a major impact on our continuing global health crisis. As populations age, we see an increased incidence in cancer rates, but considerable variation is observed in survival rates across different geographical regions and cancer types. Both breast and prostate cancer are leading causes of morbidity and mortality worldwide. Although cancer statistics indicate improvements in some areas of breast and prostate cancer prevention, diagnosis, and treatment, such statistics clearly convey the need for improvements in our understanding of the disease, risk factors, and interventions to improve life span and quality of life for all patients, and hopefully to effect a cure for people living in developed and developing countries. This concise review compiles the current information on statistics, pathophysiology, risk factors, and treatments associated with breast and prostate cancer.

Androgen synthesis inhibition increases behavioural flexibility and mPFC tyrosine hydroxylase in gonadectomized male rats

Behavioural flexibility is essential to adapt to a changing environment and depends on the medial prefrontal cortex (mPFC). Testosterone administration decreases behavioural flexibility. It is well known that testosterone is produced in the gonads, but testosterone is also produced in the brain, including the mPFC and other nodes of the mesocorticolimbic system. It is unclear how testosterone produced in the brain versus the gonads influences behavioural flexibility. Here, in adult male rats, we assessed the effects of the androgen synthesis inhibitor abiraterone acetate (ABI) and long-term gonadectomy (GDX) on behavioural flexibility in two paradigms. In Experiment 1, ABI but not GDX reduced the number of errors to criterion and perseverative errors in a strategy set-shifting task. In Experiment 2, with a separate cohort of rats, ABI but not GDX reduced perseverative errors in a reversal learning task. In Experiment 1, we also examined tyrosine hydroxylase immunoreactivity (TH-ir), and ABI but not GDX increased TH-ir in the mPFC. Our findings suggest that neurally-produced androgens modulate behavioural flexibility via modification of dopamine signalling in the mesocorticolimbic system. These results indicate that neurosteroids regulate executive functions and that ABI treatment for prostate cancer might affect cognition.

Diptoindonesin G antagonizes AR signaling and enhances the efficacy of antiandrogen therapy in prostate cancer

BACKGROUND

The androgen receptor (AR) signaling pathway has been well demonstrated to play a crucial role in the development, progression, and drug resistance of prostate cancer. Although the current anti-androgen therapy could significantly benefit prostate cancer patients initially, the efficacy of the single drug usually lasts for a relatively short period, as drug resistance quickly emerges.

METHODS

We have performed an unbiased bioinformatics analysis using the RNA-seq results in 22Rv1 cells to identify the cell response toward Dip G treatment. The RNA-seq results were validated by qRT-PCR. Protein levels were detected by western blot or staining. Cell viability was measured by Aquabluer and colony formation assay.

RESULTS

Here, we identified that Diptoindonesin G (Dip G), a natural extracted compound, could promote the proteasome degradation of AR and polo-like kinase 1 (PLK1) through modulating the activation of CHIP E3 ligase. Administration of Dip G has shown a profound efficiency in the suppression of AR and PLK1, not only in androgen-dependent LNCaP cells but also in castration-resistant and enzalutamide-resistant cells in a CHIP-dependent manner. Through co-targeting the AR signaling, Dip G robustly improved the efficacy of HSP90 inhibitors and enzalutamide in both human prostate cancer cells and in vivo xenograft mouse model.

CONCLUSIONS

Our results revealed that Dip G-mediated AR degradation would be a promising and valuable therapeutic strategy in the clinic.

High intratumoral dihydrotestosterone is associated with antiandrogen resistance in VCaP prostate cancer xenografts in castrated mice

Antiandrogen treatment resistance is a major clinical concern in castration-resistant prostate cancer (CRPC) treatment. Using xenografts of VCaP cells we showed that growth of antiandrogen resistant CRPC tumors were characterized by a higher intratumor dihydrotestosterone (DHT) concentration than that of treatment responsive tumors. Furthermore, the slow tumor growth after adrenalectomy was associated with a low intratumor DHT concentration. Reactivation of androgen signaling in enzalutamide-resistant tumors was further shown by the expression of several androgen-dependent genes. The data indicate that intratumor DHT concentration and expression of several androgen-dependent genes in CRPC lesions is an indication of enzalutamide treatment resistance and an indication of the need for further androgen blockade. The presence of an androgen synthesis, independent of CYP17A1 activity, has been shown to exist in prostate cancer cells, and thus, novel androgen synthesis inhibitors are needed for the treatment of enzalutamide-resistant CRPC tumors that do not respond to abiraterone.

The kinesin KIF20A promotes progression to castration-resistant prostate cancer through autocrine activation of the androgen receptor

Prostate cancer that recurs following androgen-deprivation therapy is termed castration-resistant, which is incurable and is marked by reactivation of androgen receptor (AR) signaling. KIF20A, a kinesin with unique structural features, is overexpressed in human castration-resistant prostate cancer (CRPC) compared to androgen-dependent PC and benign tissue. KIF20A has well-described roles in mitotic processes, but it has a less characterized function in vesicle fission and trafficking within Golgi-driven secretory pathways. Stable expression of KIF20A in androgen-dependent PC cells promoted progression to CRPC through the activation of AR signaling in vitro and in vivo. KIF20A expression resulted in the secretion of autocrine factors in the conditioned media that activated AR and caused castration-resistant proliferation of naïve androgen-dependent cells. Pharmacologic disruption of vesicle biogenesis blocked KIF20A-driven castration-resistant proliferation of androgen-dependent PC. KIF20A depletion or treatment with the KIF20A-specific inhibitor, paprotrain, reduced CRPC. These data are the first to establish KIF20A as a driver of CRPC progression through AR activation and as a promising therapeutic target against CRPC.

Abiraterone switches castration-resistant prostate cancer dependency from adrenal androgens towards androgen receptor variants and glucocorticoid receptor signalling

INTRODUCTION

Castration-resistant prostate cancer (CRPC) remains dependent on androgen receptor (AR) signalling, which is largely driven by conversion of adrenal androgen precursors lasting after castration. Abiraterone, an inhibitor of the steroidogenic enzyme CYP17A1, has been demonstrated to reduce adrenal androgen synthesis and prolong CRPC patient survival. To study mechanisms of resistance to castration and abiraterone, we created coculture models using human prostate and adrenal tumours.

MATERIALS AND METHODS

Castration-naïve and CRPC clones of VCaP were incubated with steroid substrates or cocultured with human adrenal cells (H295R) and treated with abiraterone or the antiandrogen enzalutamide. Male mice bearing VCaP xenografts with and without concurrent H295R xenografts were castrated and treated with placebo or abiraterone. Response was assessed by tumour growth and PSA release. Plasma and tumour steroid levels were assessed by LC/MS-MS. Quantitative polymerase chain reaction determined steroidogenic enzyme, nuclear receptor and AR target gene expression.

RESULTS

In vitro, adrenal androgens induced castration-naïve and CRPC cell growth, while precursors steroids for de novo synthesis did not. In a coculture system, abiraterone blocked H295R-induced growth of VCaP cells. In vivo, H295R promoted castration-resistant VCaP growth. Abiraterone only inhibited VCaP growth or PSA production in the presence of H295R. Plasma steroid levels demonstrated CYP17A1 inhibition by abiraterone, whilst CRPC tumour tissue steroid levels showed no evidence of de novo intratumoural androgen production. Castration-resistant and abiraterone-resistant VCaP tumours had increased levels of AR, AR variants and glucocorticoid receptor (GR) resulting in equal AR target gene expression levels compared to noncastrate tumours.

CONCLUSIONS

In our model, ligand-dependent AR-regulated regrowth of CRPC was predominantly supported via adrenal androgen precursor production while there was no evidence for intratumoural androgen synthesis. Abiraterone-resistant tumours relied on AR overexpression, expression of ligand-independent AR variants and GR signalling.

Statins and prostate cancer-hype or hope? The biological perspective

Growing evidence suggests that men prescribed a statin for cholesterol control have a lower risk of advanced prostate cancer (PCa) and improved treatment outcomes; however, the mechanism by which statins elicit their anti-neoplastic effects is not well understood and is likely multifaceted. Statins are potent and specific inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), the rate-limiting enzyme of the mevalonate (MVA) metabolic pathway. This two-part series is a review of the observational and experimental data on statins as anti-cancer agents in PCa. In this article, we describe the functional role that deregulated MVA metabolism plays in PCa progression and summarize the biological evidence and rationale for targeting the MVA pathway, with statins and other agents, for the treatment of PCa.

Cancer metabolism and tumor microenvironment: fostering each other?

The changes associated with malignancy are not only in cancer cells but also in environment in which cancer cells live. Metabolic reprogramming supports tumor cell high demand of biogenesis for their rapid proliferation, and helps tumor cell to survive under certain genetic or environmental stresses. Emerging evidence suggests that metabolic alteration is ultimately and tightly associated with genetic changes, in particular the dysregulation of key oncogenic and tumor suppressive signaling pathways. Cancer cells activate HIF signaling even in the presence of oxygen and in the absence of growth factor stimulation. This cancer metabolic phenotype, described firstly by German physiologist Otto Warburg, insures enhanced glycolytic metabolism for the biosynthesis of macromolecules. The conception of metabolite signaling, i.e., metabolites are regulators of cell signaling, provides novel insights into how reactive oxygen species (ROS) and other metabolites deregulation may regulate redox homeostasis, epigenetics, and proliferation of cancer cells. Moreover, the unveiling of noncanonical functions of metabolic enzymes, such as the moonlighting functions of phosphoglycerate kinase 1 (PGK1), reassures the importance of metabolism in cancer development. The metabolic, microRNAs, and ncRNAs alterations in cancer cells can be sorted and delivered either to intercellular matrix or to cancer adjacent cells to shape cancer microenvironment via media such as exosome. Among them, cancer microenvironmental cells are immune cells which exert profound effects on cancer cells. Understanding of all these processes is a prerequisite for the development of a more effective strategy to contain cancers.

Combination therapy with novel androgen receptor antagonists and statin for castration-resistant prostate cancer

BACKGROUND

One of the growth mechanisms of castration-resistant prostate cancer (CRPC) is de novo androgen synthesis from intracellular cholesterol, and statins may be able to inhibit this mechanism. In addition, statins have been reported to suppress the expression of androgen receptors (ARs) in prostate cancer cell lines. In this study, we investigated a combination therapy of novel AR antagonists and statin, simvastatin, for CRPC.

METHODS

LNCaP, 22Rv1, and PC-3 human prostate cancer cell lines were used. We developed androgen-independent LNCaP cells (LNCaP-LA). Microarray analysis was performed, followed by pathway analysis, and mRNA and protein expression was evaluated by quantitative real-time polymerase chain reaction and Western blot analysis, respectively. Cell viability was determined by MTS assay and cell counts. All evaluations were performed on cells treated with simvastatin and with or without AR antagonists (enzalutamide, apalutamide, and darolutamide).

RESULTS

The combination of darolutamide and simvastatin most significantly suppressed proliferation in LNCaP-LA and 22Rv1 cells. In a 22Rv1-derived mouse xenograft model, the combination of darolutamide and simvastatin enhanced the inhibition of cell proliferation. In LNCaP-LA cells, the combination of darolutamide and simvastatin led to reduction in the mRNA expression of the androgen-stimulated genes, KLK2 and PSA; however, this reduction in expression did not occur in 22Rv1 cells. The microarray data and pathway analyses showed that the number of differentially expressed genes in the darolutamide and simvastatin-treated 22Rv1 cells was the highest in the pathway termed "role of cell cycle." Consequently, we focused our efforts on the cell cycle regulator polo-like kinase 1 (PLK1), cyclin-dependent kinase 2 (CDK2), and cell cycle division 25C (CDC25C). In 22Rv1 cells, the combination of darolutamide and simvastatin suppressed the mRNA and protein expression of these three genes. In addition, in PC-3 cells (which lack AR expression), the combination of simvastatin and darolutamide enhanced the suppression of cell proliferation and expression of these genes.

CONCLUSIONS

Simvastatin alters the expression of many genes involved in the cell cycle in CRPC cells. Thus, the combination of novel AR antagonists (darolutamide) and simvastatin can potentially affect CRPC growth through both androgen-dependent and androgen-independent mechanisms.

Prostate cancer cell proliferation is influenced by LDL-cholesterol availability and cholesteryl ester turnover

BACKGROUND

Prostate cancer growth is driven by androgen receptor signaling, and advanced disease is initially treatable by depleting circulating androgens. However, prostate cancer cells inevitably adapt, resulting in disease relapse with incurable castrate-resistant prostate cancer. Androgen deprivation therapy has many side effects, including hypercholesterolemia, and more aggressive and castrate-resistant prostate cancers typically feature cellular accumulation of cholesterol stored in the form of cholesteryl esters. As cholesterol is a key substrate for de novo steroidogenesis in prostate cells, this study hypothesized that castrate-resistant/advanced prostate cancer cell growth is influenced by the availability of extracellular, low-density lipoprotein (LDL)-derived, cholesterol, which is coupled to intracellular cholesteryl ester homeostasis.

METHODS

C4-2B and PC3 prostate cancer cells were cultured in media supplemented with fetal calf serum (FCS), charcoal-stripped FCS (CS-FCS), lipoprotein-deficient FCS (LPDS), or charcoal-stripped LPDS (CS-LPDS) and analyzed by a variety of biochemical techniques. Cell viability and proliferation were measured by MTT assay and Incucyte, respectively.

RESULTS

Reducing lipoprotein availability led to a reduction in cholesteryl ester levels and cell growth in C4-2B and PC3 cells, with concomitant reductions in PI3K/mTOR and p38MAPK signaling. This reduced growth in LPDS-containing media was fully recovered by supplementation of exogenous low-density lipoprotein (LDL), but LDL only partially rescued growth of cells cultured with CS-LPDS. This growth pattern was not associated with changes in androgen receptor signaling but rather increased p38MAPK and MEK1/ERK/MSK1 activation. The ability of LDL supplementation to rescue cell growth required cholesterol esterification as well as cholesteryl ester hydrolysis activity. Further, growth of cells cultured in low androgen levels (CS-FCS) was suppressed when cholesteryl ester hydrolysis was inhibited.

CONCLUSIONS

Overall, these studies demonstrate that androgen-independent prostate cancer cell growth can be influenced by extracellular lipid levels and LDL-cholesterol availability and that uptake of extracellular cholesterol, through endocytosis of LDL-derived cholesterol and subsequent delivery and storage in the lipid droplet as cholesteryl esters, is required to support prostate cancer cell growth. This provides new insights into the relationship between extracellular cholesterol, intracellular cholesterol metabolism, and prostate cancer cell growth and the potential mechanisms linking hypercholesterolemia and more aggressive prostate cancer.

Downregulation of Dihydrotestosterone and Estradiol Levels by HEXIM1

We have previously reported that hexamethylene bis-acetamide inducible protein 1 (HEXIM1) inhibits the activity of ligand-bound estrogen receptor α (ERα) and the androgen receptor (AR) by disrupting the interaction between these receptors and positive transcriptional elongation factor b (P-TEFb) and attenuating RNA polymerase II (RNAPII) phosphorylation at serine 2. Functional consequences of the inhibition of transcriptional activity of ERα and AR by HEXIM1 include the inhibition of ERα- and AR-dependent gene expression, respectively, and the resulting attenuation of breast cancer (BCa) and prostate cancer (PCa) cell proliferation and growth. In our present study, we determined that HEXIM1 inhibited AKR1C3 expression in BCa and PCa cells. AKR1C3, also known as 17β-hydroxysteroid dehydrogenase (17β-HSD) type 5, is a key enzyme involved in the synthesis of 17β-estradiol (E2) and 5-dihydrotestosterone (DHT). Downregulation of AKR1C3 by HEXIM1 influenced E2 and DHT production, estrogen- and androgen-dependent gene expression, and cell proliferation. Our studies indicate that HEXIM1 has the unique ability to inhibit both the transcriptional activity of the ER and AR and the synthesis of the endogenous ligands of these receptors.

The Transcription Factors Zeb1 and Snail Induce Cell Malignancy and Cancer Stem Cell Phenotype in Prostate Cells, Increasing Androgen Synthesis Capacity and Therapy Resistance

Prostate cancer (PCa) incidence has increased during the last decades, becoming one of the leading causes of death by cancer in men worldwide. During an extended period of prostate cancer, malignant cells are androgen-sensitive being testosterone the main responsible for tumor growth. Accordingly, treatments blocking production and action of testosterone are mostly used. However, during disease progression, PCa cells become androgen insensitive producing a castration-resistant stage with a worse prognosis. Overcoming castration-resistant prostate cancer (CRPC) has become a great challenge in the management of this disease. In the search for molecular pathways leading to therapy resistance, the epithelial-mesenchymal transition (EMT), and particularly the transcription factors zinc finger E-box-binding homeobox 1 (Zeb1) and zinc finger protein SNAI1 (Snail), master genes of the EMT, have shown to have pivotal roles. Also, the discovery that cancer stem cells (CSCs) can be generated de novo from their non-CSCs counterpart has led to the question whereas these EMT transcription factors could be implicated in this dynamic conversion between non-CSC and CSC. In this review, we analyze evidence supporting the idea that Zeb1 and Snail induce cell malignancy and cancer stem cell phenotype in prostate cells, increasing androgen synthesis capacity and therapy resistance.

Osteoblasts Promote Prostate Cancer Cell Proliferation Through Androgen Receptor Independent Mechanisms

Patients with metastatic prostate cancer frequently develop bone metastases that elicit significant skeletal morbidity and increased mortality. The high tropism of prostate cancer cells for bone and their tendency to induce the osteoblastic-like phenotype are a result of a complex interplay between tumor cells and osteoblasts. Although the role of osteoblasts in supporting prostate cancer cell proliferation has been reported by previous studies, their precise contribution in tumor growth remains to be fully elucidated. Here, we tried to dissect the molecular signaling underlining the interactions between castration-resistant prostate cancer (CRPC) cells and osteoblasts using in vitro co-culture models. Transcriptomic analysis showed that osteoblast-conditioned media (OCM) induced the overexpression of genes related to cell cycle in the CRPC cell line C4-2B but, surprisingly, reduced androgen receptor (AR) transcript levels. In-depth analysis of AR expression in C4-2B cells after OCM treatment showed an AR reduction at the mRNA (p = 0.0047), protein (p = 0.0247), and functional level (p = 0.0029) and, concomitantly, an increase of C4-2B cells in S-G2-M cell cycle phases (p = 0.0185). An extensive proteomic analysis revealed in OCM the presence of some molecules that reduced AR activation, and among these, Matrix metalloproteinase-1 (MMP-1) was the only one able to block AR function (0.1 ng/ml p = 0.006; 1 ng/ml p = 0.002; 10 ng/ml p = 0.0001) and, at the same time, enhance CRPC proliferation (1 ng/ml p = 0.009; 10 ng/ml p = 0.033). Although the increase of C4-2B cell growth induced by MMP-1 did not reach the proliferation levels observed after OCM treatment, the addition of Vorapaxar, an MMP-1 receptor inhibitor (Protease-activated receptor-1, PAR-1), significantly reduced C4-2B cell cycle (0.1 μM p = 0.014; 1 μM p = 0.0087). Overall, our results provide a novel AR-independent mechanism of CRPC proliferation and suggest that MMP-1/PAR-1 could be one of the potential pathways involved in this process.

Systemic Triple Therapy in Metastatic Hormone-Sensitive Prostate Cancer (mHSPC): Ready for Prime Time or Still to Be Explored?

For decades, mono androgen deprivation therapy (ADT) has been the gold standard for metastatic hormone-sensitive prostate cancer (mHSPC) treatment. Several studies have been published within the last seven years demonstrating a significant survival advantage by combination treatment with standard ADT plus docetaxel or androgen receptor-axis-targeted therapy (ARAT) compared to ADT monotherapy. As a result, overall survival can be prolonged by at least 18 months. Recently published congress data of the PEACE-1 study suggests that in the future, triple therapy might be the new gold standard. In addition to this study, which has shown that triple treatment with standard ADT plus docetaxel plus abiraterone is superior to standard ADT plus docetaxel, several other phase III triple therapy studies are currently ongoing. The different modes of action that are investigated reach from AR-targeting over mitotic inhibition and immunotherapy to PARP and AKT inhibition. In this review we will explore if triple therapy has the potential to be the new standard for mHSPC treatment in the near future.

Low Carbohydrate Diets in Cancer Therapeutics: Current Evidence

Low carbohydrate diets have a promising mechanistic rationale in the treatment of cancer with favorable preclinical data. The strongest data suggest synergistic effects of dietary interventions with traditional cancer therapies. Recent prospective clinical trials suggest that low carbohydrate diets are safely and feasibly added within a busy oncology clinic, with hopeful additive effects in treatment enhancement.