Androgen receptor functions in castration-resistant prostate cancer and mechanisms of resistance to new agents targeting the androgen axis

Heterogeneous Responses to High-Dose Testosterone in Castration-Resistant Prostate Cancer Tumors with Mixed Rb-Proficient and Rb-Deficient Cells

Androgen deprivation therapy remains a cornerstone in managing prostate cancer. However, its recurrence often leads to the more aggressive castration-resistant prostate cancer (CRPC). Although second-line androgen receptor signaling inhibition treatments such as enzalutamide and abiraterone are available, their effectiveness against CRPC is only transient. High-dose testosterone (Hi-T) has recently emerged as a promising treatment for CRPC, primarily through the suppression of E2F and MYC signaling. However, the roles of Rb family proteins in influencing this therapeutic response remain debated. In this study, we utilized a CRPC patient-derived xenograft model that includes both Rb pathway-proficient and -deficient cell populations based on the positive or negative expression of RB family genes. Single-cell RNA sequencing analysis revealed that Rb-proficient cells displayed a robust response to Hi-T, whereas Rb-deficient cells exhibited significant resistance. Notably, our analysis indicated increased enrichment of the hypoxia signature in the Rb-deficient cell population. Further studies in RB1-silenced CRPC cell lines showed that treatment with a hypoxia-inducible factor-1α inhibitor can restore the sensitivity of Rb-deficient cells to high-dose dihydrotestosterone treatment. In conclusion, our research provides new molecular insights into CRPC tumor cell responses to Hi-T and proposes a new strategy to resensitize Rb-deficient CRPC cells to Hi-T treatment.

Preclinical Evaluation of Bavdegalutamide (ARV-110), a Novel PROteolysis TArgeting Chimera Androgen Receptor Degrader

Androgen receptor (AR) signaling is the principal driver of prostate cancer, and drugs that target this pathway (e.g., abiraterone and enzalutamide) are standard treatments for metastatic hormone-sensitive prostate cancer and metastatic castration-resistant prostate cancer. However, continual evolution during prostate cancer progression can result in AR alterations (e.g., mutation, amplification, and splicing) that can cause tumors to become resistant to these therapies. Bavdegalutamide (ARV-110) is a PROteolysis TArgeting Chimera (PROTAC) protein degrader that recruits the cereblon-containing E3 ubiquitin ligase to direct the polyubiquitination and subsequent proteasomal degradation of AR. Bavdegalutamide selectively degrades wild-type AR and most clinically relevant mutants with low nanomolar potency. The advantages of the degradation mechanism of action are demonstrated by the higher activity of bavdegalutamide relative to the AR antagonist enzalutamide in cell-based systems that assess effects on PSA synthesis, proliferation of prostate cancer cells, and induction of apoptosis. In an AR-expressing patient-derived xenograft mouse model, bavdegalutamide showed substantial AR degradation and greater tumor growth inhibition compared with enzalutamide. Bavdegalutamide also showed robust tumor growth inhibition in enzalutamide- and abiraterone-resistant prostate cancer animal models and enhanced activity in combination with abiraterone. These promising preclinical data supported the clinical development of bavdegalutamide as a potential treatment for patients with prostate cancer. Bavdegalutamide was the first PROTAC protein degrader to enter human clinical trials, specifically in patients with metastatic castration-resistant prostate cancer in a phase I/II study (NCT03888612).

Oncogenic potential of truncated-Gli3 via the Gsk3β/Gli3/AR-V7 axis in castration-resistant prostate cancer

The functional activation of the androgen receptor (AR) and its interplay with the aberrant Hh/Gli cascade are pivotal in the progression of castration-resistant prostate cancer (CRPC) and resistance to AR-targeted therapies. Our study unveiled a novel role of the truncated form of Gli (t-Gli3) in advancing CRPC. Investigation into Gli3 regulation revealed a Smo-independent mechanism for its activation. Despite lacking a transactivation domain, t-Gli3 relies on androgen receptor variant 7 (AR-V7) for its action. Mechanistically, Gsk3β activation led to the t-Gli3 generation, and inhibition of Gsk3β supported the accumulation of full-length Gli3 expression through a non-canonical mechanism. Knockdown of Gsk3β (Gsk3β KD) reduces CRPC cell proliferation, induces apoptosis via mitochondrial fragmentation, and triggers metabolomic reprogramming. The in vivo studies with Gsk3β KD cells in the mouse prostate resulted in tumor growth retardation compared to scramble cells. RNA-seq HALLMARK Gene Set Enrichment Analysis (GSEA) analysis of Gsk3β KD revealed a positive enrichment of apoptosis, tumor suppressor gene, and negative enrichment of oncogenic pathway. Furthermore, combinational use of a Gsk3β inhibitor with anti-Smo or Gli1 significantly inhibited the CRPC cell growth, which is resistant to individual Smo or Gli1 inhibitor targeting. Intriguingly, solely targeting Gli3 showed effectiveness in inhibiting CRPC cell growth. Overall, our study underscores the clinical significance of Gli3, emphasizing t-Gli3, and provides novel insights into the interplay of the Gsk3β/t-Gli3/AR-V7 axis in CRPC.

Androgen receptor dynamics in prostate cancer: from disease progression to treatment resistance

Prostate cancer is the most common cancer among men worldwide, especially in those over 65, and is a leading cause of cancer-related mortality. The disease typically advances from an androgen-dependent state to castration-resistant prostate cancer (CRPC), which poses significant treatment challenges. The androgen receptor (AR) on the X chromosome is a central driver in this process, activating genes that govern proliferation and survival. Mutations and amplifications of the AR are closely associated with disease progression and treatment resistance. While traditional therapies such as androgen deprivation therapy (ADT) and AR antagonists like enzalutamide have been effective, resistance persists due to reactivation of AR signaling through mechanisms like ligand-independent activation. Recent research highlights the role of epigenetic modifications in enhancing AR activity and drug resistance. The tumor microenvironment, particularly interactions with cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs), further complicates treatment by promoting aggressive tumor behavior and immune evasion. Future directions include developing next-generation AR antagonists, identifying AR-related biomarkers for personalized therapy, and exploring combinations with immune checkpoint inhibitors. Additionally, basal cell-lumen-derived organoids provide innovative models that can enhance understanding and treatment strategies in prostate cancer.

Discovery of a Potent and Selective GSPT1 Molecular Glue Degrader for the Treatment of Castration-Resistant Prostate Cancer

The treatment of castration-resistant prostate cancer (CRPC) remains a significant challenge, necessitating the development of new and promising therapeutic strategies. Utilizing molecular glue to degrade previously intractable cancer drivers represents an emerging and promising therapeutic approach to cancer treatment. In this study, we developed a novel CRBN-interacting molecular glue, 7d (XYD049), which exhibits potent and selective degradation of G1 to S phase transition 1 (GSPT1), a well-known untargetable cancer driver in diverse cancer cells. Importantly, 7d exhibits superior efficacy compared to 1 (CC-90009) in degrading GSPT1 in 22Rv1 cells with a DC50 value of 19 nM. It effectively suppresses the growth of 22Rv1 cells with an IC50 value of 0.007 ± 0.004 μM and demonstrates efficacy in inhibiting 22Rv1 tumor growth in mice. Mechanistically, via degradation of GSPT1, 7d downregulates CRPC-related oncogenes in 22Rv1 cells, including AR, AR-V7, PSA, and c-Myc. Thus, our work provides a novel GSPT1 selective degrader with potent effectiveness in targeting Myc-driven CRPC.

Castration-resistant prostate cancer is resensitized to androgen deprivation by autophagy-dependent apoptosis induced by blocking SKP2

Resistance to androgen receptor (AR)-targeted therapies for prostate cancer (PCa) is characteristic of an aggressive subtype called castration-resistant prostate cancer (CRPC) and is often associated with tumor relapse. Both relapse and poor prognosis in patients with CRPC are associated with increased abundance of the E3 ubiquitin ligase SKP2. Therefore, we investigated the therapeutic potential of combined inhibition of AR and SKP2 for CRPC. We found that combined targeting of AR and SKP2 with small-molecule inhibitors decreased proliferation in two CRPC cell lines in culture and in xenografts in humanized mice. Furthermore, combined therapy in mice markedly decreased the growth of Pten/Trp53 double-knockout tumors, a particularly invasive model of CRPC, whereas disruption of either AR or SKP2 alone only modestly suppressed their growth. Mechanistically, the inhibition of SKP2 in CRPC cells induced autophagy-dependent apoptosis and promoted luminal-associated phenotypes, which promoted responsiveness to AR-targeted therapy. These effects were further enhanced by coinhibition of AR and were not induced by the AR inhibitor alone. Our findings indicate that targeting both AR and SKP2 signaling pathways is necessary to treat CRPC.

Exploring the dual role of endoplasmic reticulum stress in urological cancers: Implications for tumor progression and cell death interactions

The endoplasmic reticulum (ER) is crucial for maintaining calcium balance, lipid biosynthesis, and protein folding. Disruptions in ER homeostasis, often due to the accumulation of misfolded or unfolded proteins, lead to ER stress, which plays a significant role in various diseases, especially cancer. Urological cancers, which account for high male mortality worldwide, pose a persistent challenge due to their incurability and tendency to develop drug resistance. Among the numerous dysregulated biological mechanisms, ER stress is a key factor in the progression and treatment response of these cancers. This review highlights the dual role of aberrant ER stress activation in urologic cancers, affecting both tumor growth and therapeutic outcomes. While ER stress can support tumor growth through pro-survival autophagy, it primarily inhibits cancer progression via apoptosis and pro-death autophagy. Interestingly, ER stress can paradoxically aid cancer progression through mechanisms such as exosome-mediated immune evasion. Additionally, the review examines how pharmacological interventions, particularly with phytochemicals, can stimulate ER stress-mediated tumor suppression. Key regulators, including PERK, IRE1α, and ATF6, are discussed for their roles in upregulating CHOP levels and triggering apoptosis. In conclusion, a deeper understanding of ER stress in urological cancers not only clarifies the complex interactions between cellular stress and cancer progression but also provides new opportunities for innovative therapeutic strategies.

PSMA Radiotheranostics in Prostate Cancer: Principles, Practice, and Future Prospects

Prostate cancer is a leading cause of cancer-related mortality in men, with metastatic castration-resistant prostate cancer presenting a substantial treatment challenge. The authors focuse on prostate-specific membrane antigen (PSMA) radiotheranostics, particularly lutetium 177 (177Lu)-PSMA radioligand therapy, as an emerging treatment modality for metastatic castration-resistant prostate cancer. The U.S. Food and Drug Administration approval of 177Lu-PSMA-617 marked a substantial advancement in the treatment paradigm of metastatic castration-resistant prostate cancer, based on the VISION trial that showed improved overall survival and quality of life compared with those for standard care. PSMA expression, assessed via PSMA PET, is crucial for patient selection and assessment of treatment eligibility. The authors discuss current practices, including therapy administration, dosing, and side effects, with a particular focus on eligibility criteria and the added value of posttherapy imaging. Response assessment criteria using PSMA PET are discussed, although these require further validation. The discussion of future directions highlights ongoing trials investigating PSMA targeting agents, the extension of radioligand therapy to earlier stages of prostate cancer, and combination therapies. This review underscores the role of PSMA radioligand therapy in the evolving landscape of prostate cancer treatment and its promise for improving patient outcomes. ©RSNA, 2024 Supplemental material is available for this article.

Prognostic role of Androgen Receptor splice variant 7 (AR-V7) in the pathogenesis of breast cancer

BACKGROUND

The Androgen Receptor (AR) has emerged as an endocrine therapy target in Breast Cancer, exhibiting up to 80% expression in clinical cases. AR-V7, a constitutively activated splice variant of AR with a truncated ligand-binding domain (LBD), demonstrates ligand-independent transcriptional activity and resistance to nonsteroidal antiandrogens like Bicalutamide or Enzalutamide, targeting the LBD. In metastatic prostate cancer, elevated AR-V7 levels lead to therapeutic resistance and increased metastasis.

METHODS

In this study, we evaluated the expression of AR and AR-V7 in cell lines and a cohort of 89 patients undergoing surgical intervention for treatment-naïve breast cancer. Further clinicopathological correlations and survival analysis were performed to evaluate the relationship between the AR and AR-V7 expression and clinical outcomes.

RESULTS

AR-V7/AR-FL ratio was elevated in the TNBC cell line and downregulation of AR-FL upon AR antagonists' treatment led to a compensatory increase in AR-V7. Clinical samples showed significantly elevated expression of AR and AR-V7 in tumors compared to control cases. Further clinicopathological correlation revealed aggressive clinical traits, higher pathological grades, and poor survival with AR-V7 expression.

CONCLUSIONS

Our study unravels AR-V7 as a marker for poor clinical outcomes, predicting breast cancer aggressiveness, and encourages consideration of AR-V7 as a probable target for therapeutic intervention.

Clinico-Pathological Factors and AR-LBD Mutations in Early and Late Castration-Resistant Prostate Cancer

Background

Prostate cancer (PCa) is not well understood because of its enormous biological heterogeneity and unreliable progression. We conducted this retrospective analysis to examine the variables predicting early and late progression to castration-resistant PCa (CRPC) for better management of this disease.

Methods

This single institutional retrospective study was conducted from January 2018 to January 2022. A total of 98 consecutive men meeting with the diagnosis of CRPC as per the inclusion criteria were included in the study and were stratified in four quartiles on the basis of time to CRPC (time to castration resistance [TTCR]) development. Early CRPC (1st quartile, TTCR = 6-12 months) and late CRPC (4th quartile, TTCR = 38-120 months) were then compared on the basis of different clinical, pathological and AR-LBD sequence to find the correlation with response duration.

Results

Median time to develop castration resistance was 25 ± 26.44 months. The mean age of the patients was 66.8 ± 9.20 years and median baseline PSA was calculated 100±685.06 ng/mL respectively. Higher Gleason score (≥7-10) was found to be significantly associated with early development of CRPC (p<0.001) and lower nadir PSA was significantly indicating late CRPC progression (p<0.005). No mutations were found in androgen receptor exon-5, 6, 7 except a homozygous mutation in the 7th intronic region, which is involved in splice variants formation playing noteworthy role in CRPC development.

Conclusion

Time for metastatic PCa to CRPC ranges from 6-120 months revealing its heterogeneous nature. Early age presentation in the clinic and high initial PSA and high grade (GS>7) at diagnosis were positively associated with early CRPC while lower nadir PSA was correlated with late CRPC progression. No remarkable genomic mutations were discovered. Therefore, more data are needed and further research is required with large no. of patients to discover the predictive prognostic biomarkers for better patients' management.

Acetylated KHSRP impairs DNA-damage-response-related mRNA decay and facilitates prostate cancer tumorigenesis

Androgen-regulated DNA damage response (DDR) is one of the essential mechanisms in prostate cancer (PCa), a hormone-sensitive disease. The heterogeneous nuclear ribonucleoprotein K (hnRNPK)-homology splicing regulatory protein known as far upstream element-binding protein 2 (KHSRP) is an RNA-binding protein that can attach to AU-rich elements in the 3' untranslated region (3'-UTR) of messenger RNAs (mRNAs) to mediate mRNA decay and emerges as a critical regulator in the DDR to preserve genome integrity. Nevertheless, how KHSRP responds to androgen-regulated DDR in PCa development remains unclear. This study found that androgen can significantly induce acetylation of KHSRP, which intrinsically drives tumor growth in xenografted mice. Moreover, enhanced KHSRP acetylation upon androgen stimuli impedes KHSRP-regulated DDR gene expression, as seen by analyzing RNA sequencing (RNA-seq) and Gene Set Enrichment Analysis (GSEA) datasets. Additionally, NAD-dependent protein deacetylase sirtuin-7 (SIRT7) is a promising deacetylase of KHSRP, and androgen stimuli impairs its interaction with KHSRP to sustain the increased KHSRP acetylation level in PCa. We first report the acetylation of KHSRP induced by androgen, which interrupts the KHSRP-regulated mRNA decay of the DDR-related genes to promote the tumorigenesis of PCa. This study provides insight into KHSRP biology and potential therapeutic strategies for PCa treatment, particularly that of castration-resistant PCa.

Targeting prostate cancer via therapeutic targeting of PIM-1 kinase by Naringenin and Quercetin

PIM-1 kinase belongs to the Ser/Thr kinases family, an attractive therapeutic target for prostate cancer. Here, we screened about 100 natural substances to find potential PIM-1 inhibitors. Two natural compounds, Naringenin and Quercetin, were finally selected based on their PIM-1 inhibitory potential and binding affinities. The docking score of Naringenin and Quercetin with PIM-1 is -8.4 and - 8.1 kcal/mol, respectively. Fluorescence binding studies revealed a strong affinity (Ka values, 3.1 × 104 M-1 and 4.6 × 107 M-1 for Naringenin and Quercetin, respectively) with excellent IC50 values for Naringenin and Quercetin (28.6 μM and 34.9 μM, respectively). Both compounds inhibited the growth of prostate cancer cells (LNCaP) in a dose-dependent manner, with the IC50 value of Naringenin at 17.5 μM and Quercetin at 8.88 μM. To obtain deeper insights into the PIM-1 inhibitory effect of Naringenin and Quercetin, we performed extensive molecular dynamics simulation studies, which provided insights into the binding mechanisms of PIM-1 inhibitors. Finally, Naringenin and Quercetin were suggested to serve as potent PIM-1 inhibitors, offering targeted treatments of prostate cancer. In addition, our findings may help to design novel Naringenin and Quercetin derivatives that could be effective in therapeutic targeting of prostate cancer.

Epigenome-wide impact of MAT2A sustains the androgen-indifferent state and confers synthetic vulnerability in ERG fusion-positive prostate cancer

Castration-resistant prostate cancer (CRPC) is a frequently occurring disease with adverse clinical outcomes and limited therapeutic options. Here, we identify methionine adenosyltransferase 2a (MAT2A) as a critical driver of the androgen-indifferent state in ERG fusion-positive CRPC. MAT2A is upregulated in CRPC and cooperates with ERG in promoting cell plasticity, stemness and tumorigenesis. RNA, ATAC and ChIP-sequencing coupled with histone post-translational modification analysis by mass spectrometry show that MAT2A broadly impacts the transcriptional and epigenetic landscape. MAT2A enhances H3K4me2 at multiple genomic sites, promoting the expression of pro-tumorigenic non-canonical AR target genes. Genetic and pharmacological inhibition of MAT2A reverses the transcriptional and epigenetic remodeling in CRPC models and improves the response to AR and EZH2 inhibitors. These data reveal a role of MAT2A in epigenetic reprogramming and provide a proof of concept for testing MAT2A inhibitors in CRPC patients to improve clinical responses and prevent treatment resistance.

Role of MicroRNA-21 in Prostate Cancer Progression and Metastasis: Molecular Mechanisms to Therapeutic Targets

The role of noncoding RNA has made remarkable progress in understanding progression, metastasis, and metastatic castration-resistant prostate cancer (mCRPC). A better understanding of the miRNAs has enhanced our knowledge of their targeting mainly at the therapy level in solid tumors, such as prostate cancer (PCa). microRNAs (miRNAs) belong to a class of endogenous RNA that deficit encoded proteins. Therefore, the role of miRNAs has been well-coined in the progression and development of PCa. miR-21 has a dual nature in its work both as a tumor suppressor and oncogenic role, but most of the recent studies showed that miR-21 is a tumor promoter and also is involved in castration-resistant prostate cancer (CRPC). Upregulation of miR-21 suppresses programmed cell death and inducing metastasis and castration resistant in PCa. miR-21 is involved in the different stages, such as proliferation, angiogenesis, migration, and invasion, and plays an important role in the progression, metastasis, and advanced stages of PCa. Recently, various studies directly linked the role of high levels of miR-21 with a poor therapeutic response in the patient of PCa. In the present review, we have explained the molecular mechanisms/pathways of miR-21 in PCa progression, metastasis, and castration resistant and summarized the role of miR-21 in diagnosis and therapeutic levels in PCa. In addition, we have spotlighted the recent therapeutic strategies for targeting different stages of PCa.

FOXA2 rewires AP-1 for transcriptional reprogramming and lineage plasticity in prostate cancer

FOXA family proteins act as pioneer factors by remodeling compact chromatin structures. FOXA1 is crucial for the chromatin binding of the androgen receptor (AR) in both normal prostate epithelial cells and the luminal subtype of prostate cancer (PCa). Recent studies have highlighted the emergence of FOXA2 as an adaptive response to AR signaling inhibition treatments. However, the role of the FOXA1 to FOXA2 transition in regulating cancer lineage plasticity remains unclear. Our study demonstrates that FOXA2 binds to distinct classes of developmental enhancers in multiple AR-independent PCa subtypes, with its binding depending on LSD1. Moreover, we reveal that FOXA2 collaborates with JUN at chromatin and promotes transcriptional reprogramming of AP-1 in lineage-plastic cancer cells, thereby facilitating cell state transitions to multiple lineages. Overall, our findings underscore the pivotal role of FOXA2 as a pan-plasticity driver that rewires AP-1 to induce the differential transcriptional reprogramming necessary for cancer cell lineage plasticity.

Co-targeting SKP2 and KDM5B inhibits prostate cancer progression by abrogating AKT signaling with induction of senescence and apoptosis

BACKGROUND

Prostate cancer (PCa) is the second-leading cause of cancer mortalities in the United States and is the most commonly diagnosed malignancy in men. While androgen deprivation therapy (ADT) is the first-line treatment option to initial responses, most PCa patients invariably develop castration-resistant PCa (CRPC). Therefore, novel and effective treatment strategies are needed. The goal of this study was to evaluate the anticancer effects of the combination of two small molecule inhibitors, SZL-P1-41 (SKP2 inhibitor) and PBIT (KDM5B inhibitor), on PCa suppression and to delineate the underlying molecular mechanisms.

METHODS

Human CRPC cell lines, C4-2B and PC3 cells, were treated with small molecular inhibitors alone or in combination, to assess effects on cell proliferation, migration, senescence, and apoptosis.

RESULTS

SKP2 and KDM5B showed an inverse regulation at the translational level in PCa cells. Cells deficient in SKP2 showed an increase in KDM5B protein level, compared to that in cells expressing SKP2. By contrast, cells deficient in KDM5B showed an increase in SKP2 protein level, compared to that in cells with KDM5B intact. The stability of SKP2 protein was prolonged in KDM5B depleted cells as measured by cycloheximide chase assay. Cells deficient in KDM5B were more vulnerable to SKP2 inhibition, showing a twofold greater reduction in proliferation compared to cells with KDM5B intact (p < 0.05). More importantly, combined inhibition of KDM5B and SKP2 significantly decreased proliferation and migration of PCa cells as compared to untreated controls (p < 0.005). Mechanistically, combined inhibition of KDM5B and SKP2 in PCa cells abrogated AKT activation, resulting in an induction of both cellular senescence and apoptosis, which was measured via Western blot analysis and senescence-associated β-galactosidase (SA-β-Gal) staining.

CONCLUSIONS

Combined inhibition of KDM5B and SKP2 was more effective at inhibiting proliferation and migration of CRPC cells, and this regimen would be an ideal therapeutic approach of controlling CRPC malignancy.

Insulin-like growth factor family and prostate cancer: new insights and emerging opportunities

Prostate cancer is the second most commonly diagnosed cancer in men. The mammalian insulin-like growth factor (IGF) family is made up of three ligands (IGF-I, IGF-II, and insulin), three receptors (IGF-I receptor (IGF-1R), insulin receptor (IR), and IGF-II receptor (IGF-2R)), and six IGF-binding proteins (IGFBPs). IGF-I and IGF-II were identified as potent mitogens and were previously associated with an increased risk of cancer development including prostate cancer. Several reports showed controversy about the expression of the IGF family and their connection to prostate cancer risk due to the high degree of heterogeneity among prostate tumors, sampling bias, and evaluation techniques. Despite that, it is clear that several IGF family members play a role in prostate cancer development, metastasis, and androgen-independent progression. In this review, we aim to expand our understanding of prostate tumorigenesis and regulation through the IGF system. Further understanding of the role of IGF signaling in PCa shows promise and needs to be considered in the context of a comprehensive treatment strategy.

Previously reported CCDC26 risk variant and novel germline variants in GALNT13, AR, and MYO10 associated with familial glioma in Finland

Predisposing factors underlying familial aggregation of non-syndromic gliomas are still to be uncovered. Whole-exome sequencing was performed in four Finnish families with brain tumors to identify rare predisposing variants. A total of 417 detected exome variants and 102 previously reported glioma-related variants were further genotyped in 19 Finnish families with brain tumors using targeted sequencing. Rare damaging variants in GALNT13, MYO10 and AR were identified. Two families carried either c.553C>T (R185C) or c.1214T>A (L405Q) on GALNT13. Variant c.553C>T is located on the substrate-binding site of GALNT13. AR c.2180G>T (R727L), which is located on a ligand-binding domain of AR, was detected in two families, one of which also carried a GALNT13 variant. MYO10 c.4448A>G (N1483S) was detected in two families and c.1511C>T (A504V) variant was detected in one family. Both variants are located on functional domains related to MYO10 activity in filopodia formation. In addition, affected cases in six families carried a known glioma risk variant rs55705857 in CCDC26 and low-risk glioma variants. These novel findings indicate polygenic inheritance of familial glioma in Finland and increase our understanding of the genetic contribution to familial glioma susceptibility.

Androgen receptor splice variants drive castration-resistant prostate cancer metastasis by activating distinct transcriptional programs

One critical mechanism through which prostate cancer (PCa) adapts to treatments targeting androgen receptor (AR) signaling is the emergence of ligand-binding domain-truncated and constitutively active AR splice variants, particularly AR-V7. While AR-V7 has been intensively studied, its ability to activate distinct biological functions compared with the full-length AR (AR-FL), and its role in regulating the metastatic progression of castration-resistant PCa (CRPC), remain unclear. Our study found that, under castrated conditions, AR-V7 strongly induced osteoblastic bone lesions, a response not observed with AR-FL overexpression. Through combined ChIP-seq, ATAC-seq, and RNA-seq analyses, we demonstrated that AR-V7 uniquely accesses the androgen-responsive elements in compact chromatin regions, activating a distinct transcription program. This program was highly enriched for genes involved in epithelial-mesenchymal transition and metastasis. Notably, we discovered that SOX9, a critical metastasis driver gene, was a direct target and downstream effector of AR-V7. Its protein expression was dramatically upregulated in AR-V7-induced bone lesions. Moreover, we found that Ser81 phosphorylation enhanced AR-V7's pro-metastasis function by selectively altering its specific transcription program. Blocking this phosphorylation with CDK9 inhibitors impaired the AR-V7-mediated metastasis program. Overall, our study has provided molecular insights into the role of AR splice variants in driving the metastatic progression of CRPC.

Significant reduction in burden of metastatic disease by intermittent docetaxel therapy in a patient with castration-resistant prostate cancer

Intermittent docetaxel therapy (IDT) is rarely used nowadays as a treatment option for men with metastatic castration-resistant prostate cancer (mCRPC) because of the widespread availability of androgen receptor axis-targeted therapy, which is less toxic. Therefore, there is limited information available on whether IDT has a clinical benefit in the treatment of men with mCRPC. This report describes the case of a 66-year-old man with a diagnosis of cT2N1M0 prostate cancer who underwent neoadjuvant combined androgen blockade and whole-pelvis radiation therapy. However, the tumor had progressed to mCRPC with metastasis to the bladder and a left pelvic lymph node within 2 years. Docetaxel had been administered as first-line chemotherapy, and the patient achieved a complete response in terms of the bladder metastasis. Docetaxel was stopped after 15 cycles. When a durable response had been maintained for more than 2 years, during which only androgen deprivation therapy was administered, the patient was switched to observation only. However, his prostate-specific antigen level gradually increased. Abiraterone was started as second-line therapy, during which there was a rapid increase in the PSA level. Computed tomography revealed further enlargement of the left pelvic lymph node, bladder metastasis, metastasis to the left common iliac lymph nodes, and several disseminated nodules around the bladder. Docetaxel was reintroduced as IDT for third-line therapy, and a complete response was achieved for all metastases, with the exception of the metastasis in the left pelvic lymph node. Thus far, the patient has survived for more than 7 years after starting docetaxel as first-line therapy for mCRPC. IDT is potentially useful in a subgroup of patients with mCRPC and could achieve long-term survival. Comprehensive genomic profiling may help physicians to select patients with mCRPC who are more likely to benefit from docetaxel than other systemic therapy.

Lysine methyltransferase SMYD2 enhances androgen receptor signaling to modulate CRPC cell resistance to enzalutamide

Androgen receptors (ARs) play key roles in prostate cancer (PCa) progression and castration-resistant prostate cancer (CRPC) resistance to drug therapy. SET and MYND domain containing protein 2 (SMYD2), a lysine methyltransferase, has been reported to promote tumors by transcriptionally methylating important oncogenes or tumor repressor genes. However, the role of SMYD2 in CRPC drug resistance remains unclear. In this study, we found that SMYD2 expression was significantly upregulated in PCa tissues and cell lines. High SMYD2 expression indicated poor CRPC-free survival and overall survival in patients. SMYD2 knockdown dramatically inhibited the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) potential of 22Rv1 and C4-2 cells. Conversely, ectopic overexpression of SMYD2 promoted these effects in 22Rv1 and C4-2 cells. Mechanistically, SMYD2 methylated and phosphorylated ARs to affect AR ubiquitination and proteasome degradation, which further alters the AR transcriptome in CRPC cells. Importantly, the SMYD2 inhibitor AZ505 had a synergistic therapeutic effect with enzalutamide in CRPC cells and mouse models; however, it could also re-sensitize resistant CRPC cells to enzalutamide. Our findings demonstrated that SMYD2 enhances the methylation and phosphorylation of ARs and affects AR ubiquitination and proteasome degradation to modulate CRPC cell resistance to enzalutamide, indicating that SMYD2 serves as a crucial oncogene in PCa and is an ideal therapeutic target for CRPC.

Expression and Clinical Significance of Non B Cell-Derived Immunoglobulins in the Urinary System and Male Reproductive System

The urinary system comprises kidneys, ureters, bladder, and urethra with its primary function being excretion, referring to the physiological process of transporting substances that are harmful or surplus out of the body. The male reproductive system consists of gonads (testis), vas deferens, and accessory glands such as the prostate. According to classical immunology theory, the tissues and organs mentioned above are not thought to produce immunoglobulins (Igs), and any Ig present in the relevant tissues under physiological and pathological conditions is believed to be derived from B cells. For instance, most renal diseases are associated with uncontrolled inflammation caused by pathogenic Ig deposited in the kidney. Generally, these pathological Igs are presumed to be produced by B cells. Recent studies have demonstrated that renal parenchymal cells can produce and secrete Igs, including IgA and IgG. Glomerular mesangial cells can express and secrete IgA, which is associated with cell survival and adhesion. Likewise, human podocytes demonstrate the ability to produce and secrete IgG, which is related to cell survival and adhesion. Furthermore, renal tubular epithelial cells also express IgG, potentially involved in the epithelial-mesenchymal transition (EMT). More significantly, renal cell carcinoma, bladder cancer, and prostate cancer have been revealed to express high levels of IgG, which promotes tumour progression. Given the widespread Ig expression in the urinary and male reproductive systems, continued efforts to elucidate the roles of Igs in renal physiological and pathological processes are necessary.

Orexins and Prostate Cancer: State of the Art and Potential Experimental and Therapeutic Perspectives

Prostate cancer (PCa) is the second most common cancer in humans. Peptides have recently been used as targeted therapeutics in cancers, due to their extensive multi-functional applications. Two hypothalamic peptides, orexins A (OXA) and B (OXB) and their specific receptors, orexin receptor 1 (OX1R) and 2 (OX2R), orchestrate several biological processes in the central nervous system and peripheral organs. However, in addition to their role in physiological responses, orexins are involved in numerous inflammatory and/or neoplastic pathologies. The presence and expression of orexins in different cancer models, including prostate cancer, and their role in inducing pro- or anti-apoptotic responses in tumor cell lines, suggest that the orexinergic system might have potential therapeutic action or function as a diagnostic marker in PCa. In addition to the traditional animal models for studying human PCa, the canine model might also serve as an additional tool, due to its clinical similarities with human prostate cancer.

Exogenous H2 S promotes ubiquitin-mediated degradation of SREBP1 to alleviate diabetic cardiomyopathy via SYVN1 S-sulfhydration

BACKGROUND

Diabetic cardiomyopathy, a distinctive complication of diabetes mellitus, has been correlated with the presence of intracellular lipid deposits. However, the intricate molecular mechanisms governing the aberrant accumulation of lipid droplets within cardiomyocytes remain to be comprehensively elucidated.

METHODS

Both obese diabetic (db/db) mice and HL-1 cells treated with 200 μmol/L palmitate and 200 μmol/L oleate were used to simulate type 2 diabetes conditions. Transmission electron microscopy is employed to assess the size and quantity of lipid droplets in the mouse hearts. Transcriptomics analysis was utilized to interrogate mRNA levels. Lipidomics and ubiquitinomics were employed to explore the lipid composition alterations and proteins participating in ubiquitin-mediated degradation in mice. Clinical data were collected from patients with diabetes-associated cardiomyopathy and healthy controls. Western blot analysis was conducted to assess the levels of proteins linked to lipid metabolism, and the biotin-switch assay was employed to quantify protein cysteine S-sulfhydration levels.

RESULTS

The administration of H2 S donor, NaHS, effectively restored hydrogen sulfide levels in both the cardiac tissue and plasma of db/db mice (+7%, P < 0.001; +5%, P < 0.001). Both db/db mice (+210%, P < 0.001) and diabetic patients (+83%, P = 0.22, n = 5) exhibit elevated plasma triglyceride levels. Treatment with GYY4137 effectively lowers triglyceride levels in db/db mice (-43%, P = 0.007). The expression of cystathionine gamma-lyase and HMG-CoA reductase degradation protein 1 (SYVN1) was decreased in db/db mice compared with the wild-type mice (cystathionine gamma-lyase: -31%, P = 0.0240; SYVN1: -35%, P = 0.01), and NaHS-treated mice (SYVN1: -31%, P = 0.03). Conversely, the expression of sterol regulatory element-binding protein 1 (SREBP1) was elevated (+91%, P = 0.007; +51%, P = 0.03 compared with control and NaHS-treated mice, respectively), along with diacylglycerol O-acyltransferase 1 (DGAT1) (+95%, P = 0.001; +35%, P = 0.02) and 1-acylglycerol-3-phosphate O-acyltransferase 3 (AGPAT3) (+88%, P = 0.01; +22%, P = 0.32). Exogenous H2 S led to a reduction in lipid droplet formation (-48%, P < 0.001), restoration of SYVN1 expression, modification of SYVN1's S-sulfhydration status and enhancement of SREBP1 ubiquitination. Overexpression of SYVN1 mutated at Cys115 decreased SREBP1 ubiquitination and increased the number of lipid droplets.

CONCLUSIONS

Exogenous H2 S enhances ubiquitin-proteasome degradation of SREBP1 and reduces its nuclear translocation by modulating SYVN1's cysteine S-sulfhydration. This pathway limits lipid droplet buildup in cardiac myocytes, ameliorating diabetic cardiomyopathy.

Recent advances in anticancer peptoids

Since most tumors become resistant to drugs in a gradual and irreversible manner, making treatment less effective over time, anticancer drugs require continuous development. Peptoids are a class of peptidomimetics that can be easily synthesized and optimized. They exhibit a number of unique characteristics, including protease resistance, non-immunogenicity, do not interfere with peptide functionality and skeleton polarity, and can adopt different conformations. They have been studied for their efficacy in different cancer therapies, and can be considered as a promising alternative molecular category for the development of anticancer drugs. Herein, we discuss the extensive recent advances in peptoids and peptoid hybrids in the treatment of cancers such as prostate, breast, lung, and other ones, in the hope of providing a reference for the further development of peptoid anticancer drugs.

Lysosome-dependent FOXA1 ubiquitination contributes to luminal lineage of advanced prostate cancer

Changes in FOXA1 (forkhead box protein A1) protein levels are well associated with prostate cancer (PCa) progression. Unfortunately, direct targeting of FOXA1 in progressive PCa remains challenging due to variations in FOXA1 protein levels, increased FOXA1 mutations at different stages of PCa, and elusive post-translational FOXA1 regulating mechanisms. Here, we show that SKP2 (S-phase kinase-associated protein 2) catalyzes K6- and K29-linked polyubiquitination of FOXA1 for lysosomal-dependent degradation. Our data indicate increased SKP2:FOXA1 protein ratios in stage IV human PCa compared to stages I-III, together with a strong inverse correlation (r = -0.9659) between SKP2 and FOXA1 levels, suggesting that SKP2-FOXA1 protein interactions play a significant role in PCa progression. Prostate tumors of Pten/Trp53 mice displayed increased Skp2-Foxa1-Pcna signaling and colocalization, whereas disruption of the Skp2-Foxa1 interplay in Pten/Trp53/Skp2 triple-null mice demonstrated decreased Pcna levels and increased expression of Foxa1 and luminal positive cells. Treatment of xenograft mice with the SKP2 inhibitor SZL P1-41 decreased tumor proliferation, SKP2:FOXA1 ratios, and colocalization. Thus, our results highlight the significance of the SKP2-FOXA1 interplay on the luminal lineage in PCa and the potential of therapeutically targeting FOXA1 through SKP2 to improve PCa control.

CYP19A1 is downregulated by BRD4 and suppresses castration-resistant prostate cancer cell invasion and proliferation by decreasing AR expression

Castration-resistant prostate cancer (CRPC) is the final stage of prostate cancer (PCa). As the main androgen in males, testosterone, and its androgen receptor (AR) play an important role in CRPC. The enzyme that catalyzes testosterone, aromatase, can be influenced by CYP19A1 activity - thus possibly affecting both AR expression and CRPC. However, the function of CYP19A1 in CRPC remains unclear. Using data derived from public databases and clinical samples, we analyzed the expression of CYP19A1 in PCa and CRPC specimens. The effect of CYP19A1 on cell invasion and proliferation was investigated in vitro and in vivo; while its function in metabolizing testosterone was detected in vitro. The effect of BRD4 on CYP19A1 and AR was investigated by qRT-PCR and western blot; whereas the effect of JQ1 on cells was assessed based on the IC50 value. We found that CYP19A1 was downregulated in CRPC samples and cells which correlated with a decrease in CRPC cell invasion and proliferation, and an increase in AR expression. Inversely, CYP19A1 affected CRPC cell invasion and proliferation by suppressing the expression of AR which may be attributed to the metabolism of testosterone by CYP19A1. Moreover, the BRD4 inhibitor JQ1 induced the CYP19A1 expression and suppressed the AR expression. Following BRD4 knockdown, CYP19A1 showed higher expression while AR expression was decreased. Our findings demonstrated that CYP19A1 could reduce CRPC cell invasion and proliferation by targeting AR, and this process could be regulated by BRD4. CYP19A1 may be a potential therapeutic target and enhance BRD4 inhibition in treating CRPC.

An unbiased seed-based RNAi selection screen identifies small RNAs that inhibit androgen signaling and prostate cancer cell growth

Blocking androgen receptor signaling is the mainstay of therapy for advanced prostate cancer (PCa). However, acquired resistance to single agents targeting this pathway results in the development of lethal castration-resistant PCa. Combination therapy approaches represent a promising strategy for the treatment of advanced disease. Here, we explore a therapeutic strategy for PCa based on the ability of shRNAs/siRNAs to function essentially as miRNAs and, via seed sequence complementarity, induce RNA interference of numerous targets simultaneously. We developed a library that contained shRNAs with all possible seed sequence combinations to identify those ones that most potently reduce cell growth and viability when expressed in PCa cells. Validation of some of these RNAi sequences indicated that the toxic effect is associated with seed sequence complementarity to the 3' UTR of AR coregulatory and essential genes. In fact, expression of siRNAs containing the identified toxic seed sequences led to global inhibition of AR-mediated gene expression and reduced expression of cell-cycle genes. When tested in mice, the toxic shRNAs also inhibited castration-resistant PCa and exhibited therapeutic efficacy in pre-established tumors. Our findings highlight RNAi of androgen signaling networks as a promising therapeutic strategy for PCa.

SETD7 functions as a transcription repressor in prostate cancer via methylating FOXA1

Dysregulation of histone lysine methyltransferases and demethylases is one of the major mechanisms driving the epigenetic reprogramming of transcriptional networks in castration-resistant prostate cancer (CRPC). In addition to their canonical histone targets, some of these factors can modify critical transcription factors, further impacting oncogenic transcription programs. Our recent report demonstrated that LSD1 can demethylate the lysine 270 of FOXA1 in prostate cancer (PCa) cells, leading to the stabilization of FOXA1 chromatin binding. This process enhances the activities of the androgen receptor and other transcription factors that rely on FOXA1 as a pioneer factor. However, the identity of the methyltransferase responsible for FOXA1 methylation and negative regulation of the FOXA1-LSD1 oncogenic axis remains unknown. SETD7 was initially identified as a transcriptional activator through its methylation of histone 3 lysine 4, but its function as a methyltransferase on nonhistone substrates remains poorly understood, particularly in the context of PCa progression. In this study, we reveal that SETD7 primarily acts as a transcriptional repressor in CRPC cells by functioning as the major methyltransferase targeting FOXA1-K270. This methylation disrupts FOXA1-mediated transcription. Consistent with its molecular function, we found that SETD7 confers tumor suppressor activity in PCa cells. Moreover, loss of SETD7 expression is significantly associated with PCa progression and tumor aggressiveness. Overall, our study provides mechanistic insights into the tumor-suppressive and transcriptional repression activities of SETD7 in mediating PCa progression and therapy resistance.

Demethylation of EHMT1/GLP Protein Reprograms Its Transcriptional Activity and Promotes Prostate Cancer Progression

Epigenetic reprogramming, mediated by genomic alterations and dysregulation of histone reader and writer proteins, plays a critical role in driving prostate cancer progression and treatment resistance. However, the specific function and regulation of EHMT1 (also known as GLP) and EHMT2 (also known as G9A), well-known histone 3 lysine 9 methyltransferases, in prostate cancer progression remain poorly understood. Through comprehensive investigations, we discovered that both EHMT1 and EHMT2 proteins have the ability to activate oncogenic transcription programs in prostate cancer cells. Silencing EHMT1/2 or targeting their enzymatic activity with small-molecule inhibitors can markedly decrease prostate cancer cell proliferation and metastasis in vitro and in vivo. In-depth analysis of posttranslational modifications of EHMT1 protein revealed the presence of methylation at lysine 450 and 451 residues in multiple prostate cancer models. Notably, we found that lysine 450 can be demethylated by LSD1. Strikingly, concurrent demethylation of both lysine residues resulted in a rapid and profound expansion of EHMT1's chromatin binding capacity, enabling EHMT1 to reprogram the transcription networks in prostate cancer cells and activate oncogenic signaling pathways. Overall, our studies provide valuable molecular insights into the activity and function of EHMT proteins during prostate cancer progression. Moreover, we propose that the dual-lysine demethylation of EHMT1 acts as a critical molecular switch, triggering the induction of oncogenic transcriptional reprogramming in prostate cancer cells. These findings highlight the potential of targeting EHMT1/2 and their demethylation processes as promising therapeutic strategies for combating prostate cancer progression and overcoming treatment resistance.

Significance

In this study, we demonstrate that EHMT1 and EHMT2 proteins drive prostate cancer development by transcriptionally activating multiple oncogenic pathways. Mechanistically, the chromatin binding of EHMT1 is significantly expanded through demethylation of both lysine 450 and 451 residues, which can serve as a critical molecular switch to induce oncogenic transcriptional reprogramming in prostate cancer cells.

LncRNA UBE2R2-AS1, as prognostic marker, promotes cell proliferation and EMT in prostate cancer

BACKGROUND

Long noncoding RNA ubiquitin-conjugating enzyme E2 R2 antisense RNA 1 (UBE2R2-AS1) has been recently reported to participate in the progression of tumors, including glioma and liver cancer. However, the roles of UBE2R2-AS1 in prostate cancer (PC) remained poorly understood.

METHODS

The expression of UBE2R2-AS1 was determined in tumor tissues and paired adjacent tissues from PC patients using quantitative reverse transcription PCR analysis. Correlation between UBE2R2-AS1 expression and clinicopathological parameters and overall survival were investigated by Chi-square test and Kaplan-Meier method analysis. The in vitro experiments, including CCK-8 assay, colony formation, flow cytometry and transwell assay were performed to investigate the functional role of UBE2R2-AS1 knockdown or overexpression on PC cell lines (PC-3 and DU145). Related protein expression levels were measured by western blot analysis.

RESULTS

Our data showed that UBE2R2-AS1 expression was significantly upregulated in PC tissues compared with that in adjacent tissues. The high levels of UBE2R2-AS1 were associated with high Gleason score, advanced clinical T stage, lymph node metastasis and poor prognosis. Knockdown of UBE2R2-AS1 suppressed cell proliferation, migration and invasion, induced cell cycle G0/G1 arrest and apoptosis in PC cells, along with decreased expression of PCNA, CDK4, Cyclin D1, Bcl-2, N-cadherin and Vimentin, and increased E-cadherin expression. Overexpression of UBE12R2-AS1 obtained the opposite results in PC cells.

CONCLUSIONS

Our findings suggest that UBE2R2-AS1 might be a potential diagnostic and/or therapeutic target in PC.

Palmitoyl acyltransferase ZDHHC7 inhibits androgen receptor and suppresses prostate cancer

The hormonal transcription factor androgen receptor (AR) is a master regulator of prostate cancer (PCa). Protein palmitoylation, which attaches a palmitate fatty acid to a substrate protein, is mediated by a class of 23 ZDHHC (Zinc-Finger DHHC motif)-family palmitoyltransferases. Although palmitoylation has been shown to modify many proteins and regulate diverse cellular processes, little is known about ZDHHC genes in cancer. Here we examined ZDHHC family gene expression in human tissue panels and identified ZDHHC7 as a PCa-relevant member. RNA-seq analyses of PCa cells with ZDHHC7 de-regulation revealed global alterations in androgen response and cell cycle pathways. Mechanistically, ZDHHC7 inhibits AR gene transcription and therefore reduces AR protein levels and abolishes AR signaling in PCa cells. Accordingly, ZDHHC7 depletion increased the oncogenic properties of PCa cells, whereas restoring ZDHHC7 is sufficient to suppress PCa cell proliferation and invasion in vitro and mitigate xenograft tumor growth in vivo. Lastly, we demonstrated that ZDHHC7 is downregulated in human PCa compared to benign-adjacent tissues, and its loss is associated with worse clinical outcomes. In summary, our study reveals a global role of ZDHHC7 in inhibiting androgen response and suppressing PCa progression and identifies ZDHHC7 loss as a biomarker for aggressive PCa and a target for therapeutic intervention.

CHRM4/AKT/MYCN upregulates interferon alpha-17 in the tumor microenvironment to promote neuroendocrine differentiation of prostate cancer

Current treatment options for prostate cancer focus on targeting androgen receptor (AR) signaling. Inhibiting effects of AR may activate neuroendocrine differentiation and lineage plasticity pathways, thereby promoting the development of neuroendocrine prostate cancer (NEPC). Understanding the regulatory mechanisms of AR has important clinical implications for this most aggressive type of prostate cancer. Here, we demonstrated the tumor-suppressive role of the AR and found that activated AR could directly bind to the regulatory sequence of muscarinic acetylcholine receptor 4 (CHRM4) and downregulate its expression. CHRM4 was highly expressed in prostate cancer cells after androgen-deprivation therapy (ADT). CHRM4 overexpression may drive neuroendocrine differentiation of prostate cancer cells and is associated with immunosuppressive cytokine responses in the tumor microenvironment (TME) of prostate cancer. Mechanistically, CHRM4-driven AKT/MYCN signaling upregulated the interferon alpha 17 (IFNA17) cytokine in the prostate cancer TME after ADT. IFNA17 mediates a feedback mechanism in the TME by activating the CHRM4/AKT/MYCN signaling-driven immune checkpoint pathway and neuroendocrine differentiation of prostate cancer cells. We explored the therapeutic efficacy of targeting CHRM4 as a potential treatment for NEPC and evaluated IFNA17 secretion in the TME as a possible predictive prognostic biomarker for NEPC.

Molecular Similarities and Differences between Canine Prostate Cancer and Human Prostate Cancer Variants

Dogs are one of few species that naturally develop prostate cancer (PCa), which clinically resembles aggressive, advanced PCa in humans. Moreover, PCa-tumor samples from dogs are often androgen receptor (AR)-negative and may enrich our understanding of AR-indifferent PCa in humans, a highly lethal subset of PCa for which few treatment modalities are available This narrative review discusses the molecular similarities between dog PCa and specific human-PCa variants, underscoring the possibilities of using the dog as a novel pre-clinical animal model for human PCa, resulting in new therapies and diagnostics that may benefit both species.

WNT5a Signaling through ROR2 Activates the Hippo Pathway to Suppress YAP1 Activity and Tumor Growth

Noncanonical Wnt signaling by WNT5a has oncogenic and tumor suppressive activities, but downstream pathways mediating these specific effects remain to be fully established. In a subset of prostate cancer organoid culture and xenograft models, inhibition of Wnt synthesis stimulated growth, whereas WNT5a or a WNT5a mimetic peptide (Foxy5) markedly suppressed tumor growth. WNT5a caused a ROR2-dependent decrease in YAP1 activity, which was associated with increased phosphorylation of MST1/2, LATS1, MOB1, and YAP1, indicating Hippo pathway activation. Deletion of MST1/2 abrogated the WNT5a response. WNT5a similarly activated Hippo in ROR2-expressing melanoma cells, whereas WNT5a in ROR2-negative cells suppressed Hippo. This suppression was associated with increased inhibitory phosphorylation of NF2/Merlin that was not observed in ROR2-expressing cells. WNT5a also increased mRNA encoding Hippo pathway components including MST1 and MST2 and was positively correlated with these components in prostate cancer clinical datasets. Conversely, ROR2 and WNT5a expression was stimulated by YAP1, and correlated with increased YAP1 activity in clinical datasets, revealing a WNT5a/ROR2 negative feedback loop to modulate YAP1 activity. Together these findings identify Hippo pathway activation as a mechanism that mediates the tumor suppressive effects of WNT5a and indicate that expression of ROR2 may be a predictive biomarker for responsiveness to WNT5a-mimetic drugs.

SIGNIFICANCE

WNT5a signaling through ROR2 activates the Hippo pathway to downregulate YAP1/TAZ activity and suppress tumor growth, identifying ROR2 as a potential biomarker to identify patients that could benefit from WNT5a-related agents.

Voluntarily wheel running inhibits the growth of CRPC xenograft by inhibiting HMGB1 in mice

INTRODUCTION

Exercise has been proved to reduce the risk of recurrence and mortality of cancer. Emerging evidence indicated that exercise may regulate both systematical and local metabolism, immunity and other ways. Although the role of exercise in inhibiting castration-resistant prostate cancer is well established, the underlying mechanism remains unclear.

METHOD

Twenty C57BL/6 male mice were used to construct CRPC xenograft models and randomly divided into exercise group (n = 10) and control group (n = 10). After exercised with voluntarily wheel running for 21 days, the mice were sacrificed and the tumor tissues and serum were collected. TUNEL staining was used to detect the apoptosis of tumor cells. The expression of PI3K signal pathway and apoptosis related proteins were detected by Western blot. The expression of AR and HMGB1 were examined by Western blot and Immunohistochemical staining. IFN-γ, TNF-α, TGF-β, IL-4, IL-6, IL-10 in serum was examined using ELISA kits.

RESULTS

Voluntarily wheel running inhibited the growth of CRPC xenografts, inhibited the proliferation of tumor cells and promoted the apoptosis of tumor cells. HMGB1 levels in serum and tumor tissues were significantly reduced after exercise, which enhanced local immunity by inducing more leukocyte infiltration and inhibited systemic inflammatory response by regulating cytokines.

CONCLUSION

Voluntary wheel running can down-regulate the expression of HMGB1 in serum and transplanted tumor tissues, inhibit proliferation and promote apoptosis of tumor cells, enhance immune cell infiltration and systemic inflammatory response, and regulate local anti-tumor effects in tumor microenvironment.

Clostridium scindens metabolites trigger prostate cancer progression through androgen receptor signaling

Prostate cancer (PCa) is one of the most common malignancies in men; recently, PCa-related mortality has increased worldwide. Although androgen deprivation therapy (ADT) is the standard treatment for PCa, patients often develop aggressive castration-resistant PCa (CRPC), indicating the presence of an alternative source of androgen. Clostridium scindens is a member of the gut microbiota and can convert cortisol to 11β-hydroxyandrostenedione (11β-OHA), which is a potent androgen precursor. However, the effect of C. scindens on PCa progression has not been determined. In this study, androgen-dependent PCa cells (LNCaP) were employed to investigate whether C. scindens-derived metabolites activate androgen receptor (AR), which is a pivotal step in the development of PCa. Results showed that cortisol metabolites derived from C. scindens-conditioned medium promoted proliferation and enhanced migration of PCa cells. Furthermore, cells treated with these metabolites presented activated AR and stimulated AR-regulated genes. These findings reveal that C. scindens has the potential to promote PCa progression via the activation of AR signaling. Further studies on the gut-prostate axis may help unravel an alternative source of androgen that triggers CRPC exacerbation.

Darolutamide for non-metastatic castration-resistant prostate cancer: Efficacy, safety, and clinical perspectives of use

Darolutamide, a second-generation androgen receptor inhibitor (SGARI), has been shown to increase metastasis-free survival and overall survival among men with non-metastatic castration-resistant prostate cancer (nmCRPC). Its unique chemical structure potentially provides efficacy and safety advantages over the SGARIs apalutamide and enzalutamide, which are also indicated for nmCRPC. Despite a lack of direct comparisons, the SGARIs appear to have similar efficacy, safety, and quality of life (QoL) results. Indirect evidence suggests that darolutamide is preferred for its good adverse event profile, an attribute valued by physicians, patients, and their caregivers for maintaining QoL. Darolutamide and others in its class are costly; access may be a challenge for many patients and may lead to modifications to guideline-recommended regimens.

Plasma progastrin-releasing peptide level shows different predictive profiles for treatment response by androgen receptor axis-targeted agents in patients with metastatic castration-resistant prostate cancer

BACKGROUND

The neuroendocrine (NE) pathway cannot be ignored as a mechanism for castration-resistant prostate cancer (CRPC) progression. The neuromediator, gastrin-releasing peptide (GRP) may be involved in the aberrant activation of the normal androgen receptor (AR) and increased AR variants. This study focused on plasma levels of progastrin-releasing peptide (ProGRP) and examined the treatment outcomes with androgen receptor axis-targeted (ARAT) agents.

METHODS

One hundred patients with metastatic CRPC were enrolled. Enzalutamide (ENZ) or abiraterone acetate/prednisone (AA/P) were administered to 50 patients each in a nonrandomized manner as a first-line or later choice. Plasma ProGRP levels were determined using a chemiluminescent enzyme immunoassay, and data were collected prospectively. The study endpoints were prostate-specific antigen (PSA) response and survival estimates.

RESULTS

In the ENZ series, ProGRP levels correlated with the maximum PSA change from baseline (high ProGRP: -34.5% vs. low ProGRP: -85.7% p = .033). PSA progression-free survival (PFS), radiographic/symptomatic (r/s) PFS, and overall survival (OS) in patients with high ProGRP were significantly worse than those in patients with low ProGRP (median PSA-PFS: 3.3 vs. 10.0 months, p = .001, r/s PFS: 5.0 vs. 15.0 months, p < 0.001, and OS 17.5 vs. 49.0 months, p < .001, respectively). In addition, ProGRP showed an independent predictive value for all survival estimates in multivariate analyses. In the AA/P series, ProGRP levels did not correlate with the PSA change or predict PSA-PFS and r/s PFS, but they maintained a significant difference in OS (19.0 vs. 48.0 months, p = .003).

CONCLUSIONS

Plasma ProGRP provides a consistent predictive value for OS in metastatic CRPC patients who underwent therapy with ARAT agents. Meanwhile, ProGRP showed different predictive profiles for PSA- and r/s PFS between ENZ and AA/P. These findings clinically suggest a mechanism for CRPC progression involving the NE pathway via the GRP. The underlying mechanism of different predictive profiles by the ARAT agent should be explored in future research.

Plk1 Inhibitors and Abiraterone Synergistically Disrupt Mitosis and Kill Cancer Cells of Disparate Origin Independently of Androgen Receptor Signaling

Abiraterone is a standard treatment for metastatic castrate-resistant prostate cancer (mCRPC) that slows disease progression by abrogating androgen synthesis and antagonizing the androgen receptor (AR). Here we report that inhibitors of the mitotic regulator polo-like kinase-1 (Plk1), including the clinically active third-generation Plk1 inhibitor onvansertib, synergizes with abiraterone in vitro and in vivo to kill a subset of cancer cells from a wide variety of tumor types in an androgen-independent manner. Gene-expression analysis identified an AR-independent synergy-specific gene set signature upregulated upon abiraterone treatment that is dominated by pathways related to mitosis and the mitotic spindle. Abiraterone treatment alone caused defects in mitotic spindle orientation, failure of complete chromosome condensation, and improper cell division independently of its effects on AR signaling. These effects, although mild following abiraterone monotherapy, resulted in profound sensitization to the antimitotic effects of Plk1 inhibition, leading to spindle assembly checkpoint-dependent mitotic cancer cell death and entosis. In a murine patient-derived xenograft model of abiraterone-resistant metastatic castration-resistant prostate cancer (mCRPC), combined onvansertib and abiraterone resulted in enhanced mitotic arrest and dramatic inhibition of tumor cell growth compared with either agent alone. Overall, this work establishes a mechanistic basis for the phase II clinical trial (NCT03414034) testing combined onvansertib and abiraterone in mCRPC patients and indicates this combination may have broad utility for cancer treatment.

SIGNIFICANCE

Abiraterone treatment induces mitotic defects that sensitize cancer cells to Plk1 inhibition, revealing an AR-independent mechanism for this synergistic combination that is applicable to a variety of cancer types.

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.

Genetic alterations in MED12 promote castration-resistant prostate cancer through modulation of GLI3 signaling

Prostate cancer is a disease that depends on androgenic stimulation and is thus commonly treated with androgen deprivation therapy (ADT). ADT is highly successful initially; however, patients inevitably relapse at which point the cancer grows independently of androgens and is termed castration-resistant prostate cancer (CRPC). CRPC develops through various mechanisms, one of these being crosstalk of the androgen receptor (AR) signaling pathway with other signaling pathways. Congruently, prior work has shown that androgen deprivation induces SHH signaling, which subsequently promotes activation of AR-dependent gene expression to promote cell growth. Mechanistically, this crosstalk involves a physical interaction between AR and components of SHH signaling, specifically proteins of the GLI transcription factor family. These findings thus suggest that activation of SHH signaling could promote the recurrence of cell growth in the absence of androgens to ultimately lead to progression towards CRPC. In this study, we have investigated this mechanism in a subset of prostate cancer that harbors genetic alterations within the Mediator subunit 12 (MED12). We found that loss of MED12 promotes the expression of GLI3 target genes which subsequently drives excessive cell growth in the absence of androgens. Thus, we conclude that genetic alterations within MED12 promote CRPC through hyperactivated GLI3 dependent sonic hedgehog signaling.

Is androgen receptor activity in metastatic prostate cancer a good biomarker for bipolar androgen therapy?

Androgen deprivation therapy (ADT) is the longstanding treatment for advanced prostate cancer (PC) because androgen receptor (AR) is the key therapeutic vulnerability for this disease. Bipolar androgen therapy (BAT) - the rapid cycling of supraphysiologic androgen (SPA) and low serum testosterone levels - is an alternative concept, but not all patients respond and acquired resistance can occur. In this issue of the JCI, Sena et al. developed a gene signature indicative of high AR activity to predict patient response to BAT, including a decline in both serum prostate-specific antigen (PSA) and tumor volume. Preclinical models showed that AR-mediated suppression of MYC, known to drive PC, was associated with decreased cell growth following SPA treatment. Because BAT eventually leads to resistance, the authors tested cycling between SPA and AR antagonism in a patient-derived xenograft and observed a delay in tumor growth. These findings represent a major step toward the informed use of BAT for advanced PC.

Tautomycin and enzalutamide combination yields synergistic effects on castration-resistant prostate cancer

The androgen receptor (AR) plays an essential role in prostate cancer progression and is a key target for prostate cancer treatment. However, patients with prostate cancer undergoing androgen deprivation therapy eventually experience biochemical relapse, with hormone-sensitive prostate cancer progressing into castration-resistant prostate cancer (CRPC). The widespread application of secondary antiandrogens, such as enzalutamide, indicates that targeting AR remains the most efficient method for CRPC treatment. Unfortunately, neither can block AR signaling thoroughly, leading to AR reactivation within several months. Here, we report an approach for suppressing reactivated AR signaling in the CRPC stage. A combination of the protein phosphatase 1 subunit α (PP1α)-specific inhibitor tautomycin and enzalutamide synergistically inhibited cell proliferation and AR signaling in LNCaP and C4-2 cells, as well as in AR variant-positive 22RV1 cells. Our results revealed that enzalutamide competed with residual androgens in CRPC, enhancing tautomycin-mediated AR degradation. In addition, the remaining competitive inhibitory role of enzalutamide on AR facilitated tautomycin-induced AR degradation in 22RV1 cells, further decreasing ARv7 levels via a full-length AR/ARv7 interaction. Taken together, our findings suggest that the combination of tautomycin and enzalutamide could achieve a more comprehensive inhibition of AR signaling in CRPC. AR degraders combined with AR antagonists may represent a new therapeutic strategy for CRPC.

Acetyl-CoA Counteracts the Inhibitory Effect of Antiandrogens on Androgen Receptor Signaling in Prostate Cancer Cells

The commonly used therapeutic management of PC involves androgen deprivation therapy (ADT) followed by treatment with AR signaling inhibitors (ARSI). However, nearly all patients develop drug-resistant disease, with a median progression-free survival of less than 2 years in chemotherapy-naïve men. Acetyl-coenzyme A (acetyl-CoA) is a central metabolic signaling molecule with key roles in biosynthetic processes and cancer signaling. In signaling, acetyl-CoA serves as the acetyl donor for acetylation, a critical post-translational modification. Acetylation affects the androgen receptor (AR) both directly and indirectly increasing expression of AR dependent genes. Our studies reveal that PC cells respond to the treatment with ARSI by increasing expression of ATP-citrate lyase (ACLY), a major enzyme responsible for cytosolic acetyl-CoA synthesis, and up-regulation of acetyl-CoA intracellular levels. Inhibition of ACLY results in a significant suppression of ligand-dependent and -independent routes of AR activation. Accordingly, the addition of exogenous acetyl-CoA, or its precursor acetate, augments AR transcriptional activity and diminishes the anti-AR activity of ARSI. Taken together, our findings suggest that PC cells respond to antiandrogens by increasing activity of the acetyl-coA pathway in order to reinstate AR signaling.

Increased AR expression in castration-resistant prostate cancer rapidly induces AR signaling reprogramming with the collaboration of EZH2

Elevated androgen receptor (AR) expression is a hallmark of castration-resistant prostate cancer (CRPC) and contributes to the restoration of AR signaling under the conditions of androgen deprivation. However, whether overexpressed AR alone with the stimulation of castrate levels of androgens can be sufficient to induce the reprogramming of AR signaling for the adaptation of prostate cancer (PCa) cells remains unclear. In this study, we used a PCa model with inducible overexpression of AR to examine the acute effects of AR overexpression on its cistrome and transcriptome. Our results show that overexpression of AR alone in conjunction with lower androgen levels can rapidly redistribute AR chromatin binding and activates a distinct transcription program that is enriched for DNA damage repair pathways. Moreover, using a recently developed bioinformatic tool, we predicted the involvement of EZH2 in this AR reprogramming and subsequently identified a subset of AR/EZH2 co-targeting genes, which are overexpressed in CRPC and associated with worse patient outcomes. Mechanistically, we found that AR-EZH2 interaction is impaired by the pre-castration level of androgens but can be recovered by the post-castration level of androgens. Overall, our study provides new molecular insights into AR signaling reprogramming with the engagement of specific epigenetic factors.

Identification of Candidate mRNA Isoforms for Prostate Cancer-Risk SNPs Utilizing Iso-eQTL and sQTL Methods

Single nucleotide polymorphisms (SNPs) impacting the alternative splicing (AS) process (sQTLs) or isoform expression (iso-eQTL) are implicated as important cancer regulatory elements. To find the sQTL and iso-eQTL, we retrieved prostate cancer (PrCa) tissue RNA-seq and genotype data originating from 385 PrCa European patients from The Cancer Genome Atlas. We conducted RNA-seq analysis with isoform-based and splice event-based approaches. The MatrixEQTL was used to identify PrCa-associated sQTLs and iso-eQTLs. The overlap between sQTL and iso-eQTL with GWAS loci and those that are differentially expressed between cancer and normal tissue were identified. The cis-acting associations (FDR < 0.05) for PrCa-risk SNPs identified 42, 123, and 90 PrCa-associated cassette exons, intron retention, and mRNA isoforms belonging to 25, 95, and 83 genes, respectively; while assessment of trans-acting association (FDR < 0.05) yielded 59, 65, and 196 PrCa-associated cassette exons, intron retention and mRNA isoforms belonging to 35, 55, and 181 genes, respectively. The results suggest that functional PrCa-associated SNPs can play a role in PrCa genesis by making an important contribution to the dysregulation of AS and, consequently, impacting the expression of the mRNA isoforms.

Bioengineered BERA-Wnt5a siRNA Targeting Wnt5a/FZD2 Signaling Suppresses Advanced Prostate Cancer Tumor Growth and Enhances Enzalutamide Treatment

The next-generation antiandrogen drugs such as enzalutamide and abiraterone extend survival times and improve quality of life in patients with advanced prostate cancer. However, resistance to both drugs occurs frequently through mechanisms that are incompletely understood. Wnt signaling, particularly through Wnt5a, plays vital roles in promoting prostate cancer progression and induction of resistance to enzalutamide and abiraterone. Development of novel strategies targeting Wnt5a to overcome resistance is an urgent need. In this study, we demonstrated that Wnt5a/FZD2-mediated noncanonical Wnt pathway is overexpressed in enzalutamide-resistant prostate cancer. In patient databases, both the levels of Wnt5a and FZD2 expression are upregulated upon the development of enzalutamide resistance and correlate with higher Gleason score, biochemical recurrence, and metastatic status, and with shortened disease-free survival duration. Blocking Wnt5a/FZD2 signal transduction not only diminished the activation of noncanonical Wnt signaling pathway, but also suppressed the constitutively activated androgen receptor (AR) and AR variants. Furthermore, we developed a novel bioengineered BERA-Wnt5a siRNA construct and demonstrated that inhibition of Wnt5a expression by the BERA-Wnt5a siRNA significantly suppressed tumor growth and enhanced enzalutamide treatment in vivo. These results indicate that Wnt5a/FZD2 signal pathway plays a critical role in promoting enzalutamide resistance, and targeting this pathway by BERA-Wnt5a siRNA can be developed as a potential therapy to treat advanced prostate cancer.