Androgen receptor with short polyglutamine tract preferably enhances Wnt/β-catenin-mediated prostatic tumorigenesis

Advances in the understanding of androgen receptor structure and function and in the development of next-generation AR-targeted therapeutics

Androgen receptor (AR) and its ligand androgens are important for development and physiology of various tissues. AR and its ligands also play critical role in the development of various diseases, making it a valuable therapeutic target. AR ligands, both agonists and antagonists, are being widely used to treat pathological conditions, including prostate cancer and hypogonadism. Despite AR being studied widely over the last five decades, the last decade has seen striking advances in the knowledge on AR and discoveries that have the potential to translate to the clinic. This review provides an overview of the advances in AR biology, AR molecular mechanisms of action, and next generation molecules that are currently in development. Several of the areas described in the review are just unraveling and the next decade will bring more clarity on these developments that will put AR at the forefront of both basic biology and drug development.

GPX2 predicts recurrence-free survival and triggers the Wnt/β-catenin/EMT pathway in prostate cancer

Objective

This study aimed to establish a prognostic model related to prostate cancer (PCa) recurrence-free survival (RFS) and identify biomarkers.

Methods

The RFS prognostic model and key genes associated with PCa were established using Least Absolute Shrinkage and Selection Operator (LASSO) and Cox regression from the Cancer Genome Atlas (TCGA)-PRAD and the Gene Expression Omnibus (GEO) GSE46602 datasets. The weighted gene co-expression network (WGCNA) was used to analyze the obtained key modules and genes, and gene set enrichment analysis (GSEA) was performed. The phenotype and mechanism were verified in vitro.

Results

A total of 18 genes were obtained by LASSO regression, and an RFS model was established and verified (TCGA, AUC: 0.774; GSE70768, AUC: 0.759). Three key genes were obtained using multivariate Cox regression. WGCNA analysis obtained the blue module closely related to the Gleason score (cor = -0.22, P = 3.3e - 05) and the unique gene glutathione peroxidase 2 (GPX2). Immunohistochemical analysis showed that the expression of GPX2 was significantly higher in patients with PCa than in patients with benign prostatic hyperplasia (P < 0.05), but there was no significant correlation with the Gleason score (GSE46602 and GSE6919 verified), which was also verified in the GSE46602 and GSE6919 datasets. The GSEA results showed that GPX2 expression was mainly related to the epithelial-mesenchymal transition (EMT) and Wnt pathways. Additionally, GPX2 expression significantly correlated with eight kinds of immune cells. In human PCa cell lines LNCaP and 22RV1, si-GPX2 inhibited proliferation and invasion, and induced apoptosis when compared with si-NC. The protein expression of Wnt3a, glycogen synthase kinase 3β (GSK3β), phosphorylated (p)-GSK3β, β-catenin, p-β-catenin, c-myc, cyclin D1, and vimentin decreased; the expression of E-cadherin increased; and the results for over-GPX2 were opposite to those for over-NC. The protein expression of GPX2 decreased, and β-catenin was unchanged in the si-GPX2+ SKL2001 group compared with the si-NC group.

Conclusion

We successfully constructed the PCa RFS prognostic model, obtained RFS-related biomarker GPX2, and found that GPX2 regulated PCa progression and triggered Wnt/β-catenin/EMT pathway molecular changes.

The evolution and polymorphism of mono-amino acid repeats in androgen receptor and their regulatory role in health and disease

Androgen receptor (AR) is a key member of nuclear hormone receptors with the longest intrinsically disordered N-terminal domain (NTD) in its protein family. There are four mono-amino acid repeats (polyQ1, polyQ2, polyG, and polyP) located within its NTD, of which two are polymorphic (polyQ1 and polyG). The length of both polymorphic repeats shows clinically important correlations with disease, especially with cancer and neurodegenerative diseases, as shorter and longer alleles exhibit significant differences in expression, activity and solubility. Importantly, AR has also been shown to undergo condensation in the nucleus by liquid-liquid phase separation, a process highly sensitive to protein solubility and concentration. Nonetheless, in prostate cancer cells, AR variants also partition into transcriptional condensates, which have been shown to alter the expression of target gene products. In this review, we summarize current knowledge on the link between AR repeat polymorphisms and cancer types, including mechanistic explanations and models comprising the relationship between condensate formation, polyQ1 length and transcriptional activity. Moreover, we outline the evolutionary paths of these recently evolved amino acid repeats across mammalian species, and discuss new research directions with potential breakthroughs and controversies in the literature.

Interferon Beta (IFN-β)-Modified Bone Marrow Mesenchymal Stem Cells (BMSC) Impede Metastatic Tropism of Prostate Cancer via Modulating Transforming Growth Factor-Beta/Smads (TGF-Beta/Smads) Pathway

The study of Bone marrow mesenchymal stem cells (BMSCs)-based treatment is still unmet needs topic in recent years, especially focusing on the therapeutic effects of genetically modified BMSCs. IFN-β acts as a critical mediator in the occurrence and progress of prostate cancer. Additionally, its related signal transduction pathways affect malignancies. This study aims to discussion the mechanism of IFN-β-modified BMSCs in impeding the metastatic tropism of prostate cancer. A total of 40 male mice (SPF) with a clean grade were randomized into 4 groups (10 mice per group) as follows: control group, BMSCs group, IFN-β modified BMSCs group and TGF-beta/Smads inhibitor group. The following indicators were investigated: the expression level of IFN-β in IFN-β-modified BMSCs, in vitro metastatic tropism of prostate cancer cells, quantification of TGF-beta and Smads protein, along with the targeting of IFN-β and TGF-beta/Smads. The expression of IFN-β level was significantly increased denoted in the modified BMSCs (1.82±0.42) in comparison with those unmodified BMSCs (P < 0.05). After 48- and 72-hour culture, the proportion of migrating cells in the IFN-β-modified BMSCs group was significantly decreased than those in other groups (P < 0.05). Meanwhile, cells in the TGF-beta/Smads inhibitor group exhibited a significantly weaker tendency to migrate in comparison with those in the control group and BMSCs group, but still showed more migrating cells compared to cells in the IFN-β-modified BMSCs group (P < 0.05). Moreover, a significant reduction of migrated cells was denoted in the BMSCs group after 48- and 72-hour culture in comparison with the control group (P < 0.05). The weakest expression of TGF-beta/Smads proteins was denoted in the IFN-β-modified BMSCs group, followed by the TGF-beta/Smads inhibitor group, BMSCs group and control group (P < 0.05). The TGF-beta/Smads inhibitor group exhibited significantly decreased levels of TGF-beta/Smads proteins in comparison with the control group and BMSCs group (P < 0.05). Moreover, a significant decline of TGF-beta/Smads proteins was denoted in the BMSCs group in comparison with the control group (P < 0.05). The IFN-β gene was incubated separately with wild-type and mutant plasmids in the dual-luciferase reporter gene assay. The results indicated that the expression of IFN-β was stronger in the mutant plasmids (P < 0.05) IFN-β-modified BMSCs can boost the entrance of IFN-β into prostate cancer cells, thereby enhancing their expression of IFN-β, which resulted in the expression impediment of TGF-beta/Smads signals, leading to an inhibited metastatic tropism of prostate cancer cells. Its mechanism was mainly related to the TGF-beta/Smads signal transduction pathway.

Comparative Pathobiology of Canine and Human Prostate Cancer: State of the Art and Future Directions

First described in 1817, prostate cancer is considered a complex neoplastic entity, and one of the main causes of death in men in the western world. In dogs, prostatic carcinoma (PC) exhibits undifferentiated morphology with different phenotypes, is hormonally independent of aggressive character, and has high rates of metastasis to different organs. Although in humans, the risk factors for tumor development are known, in dogs, this scenario is still unclear, especially regarding castration. Therefore, with the advent of molecular biology, studies were and are carried out with the aim of identifying the main molecular mechanisms and signaling pathways involved in the carcinogenesis and progression of canine PC, aiming to identify potential biomarkers for diagnosis, prognosis, and targeted treatment. However, there are extensive gaps to be filled, especially when considering the dog as experimental model for the study of this neoplasm in humans. Thus, due to the complexity of the subject, the objective of this review is to present the main pathobiological aspects of canine PC from a comparative point of view to the same neoplasm in the human species, addressing the historical context and current understanding in the scientific field.

Exploring the Wnt Pathway as a Therapeutic Target for Prostate Cancer

Aberrant activation of the Wnt pathway is emerging as a frequent event during prostate cancer that can facilitate tumor formation, progression, and therapeutic resistance. Recent discoveries indicate that targeting the Wnt pathway to treat prostate cancer may be efficacious. However, the functional consequence of activating the Wnt pathway during the different stages of prostate cancer progression remains unclear. Preclinical work investigating the efficacy of targeting Wnt signaling for the treatment of prostate cancer, both in primary and metastatic lesions, and improving our molecular understanding of treatment responses is crucial to identifying effective treatment strategies and biomarkers that help guide treatment decisions and improve patient care. In this review, we outline the type of genetic alterations that lead to activated Wnt signaling in prostate cancer, highlight the range of laboratory models used to study the role of Wnt genetic drivers in prostate cancer, and discuss new mechanistic insights into how the Wnt cascade facilitates prostate cancer growth, metastasis, and drug resistance.

Coexpression network analysis identified lncRNAs-mRNAs with potential relevance in African ancestry prostate cancer

AIM

This study aims to investigate similarities and differences using lncRNA and mRNA coexpression network analysis in African ancestry (AA) and European ancestry (EA) among prostate cancer (PCa) patients.

METHODS

We performed weighted gene coexpression network analysis of the expression from 49 of AA and 49 of EA to identify lncRNAs-mRNAs.

RESULTS

27 lncRNAs and 36 mRNAs were highly expressed in patients of AA. Two mRNAs and their antisense lncRNAs were expressed. Additionally, seven mRNAs were DE or coexpressed and had an impact on survival.

CONCLUSION

We present a list of lncRNAs and mRNAs that were DE and coexpressed when comparing patients of AA and EA, and these data are a resource for future studies to understand the role of lncRNAs.

Clinical Outcomes and Racial Disparities in Metastatic Hormone-Sensitive Prostate Cancer in the Era of Novel Treatment Options

BACKGROUND

Docetaxel (DOC) and abiraterone (ABI) in the upfront setting have separately improved clinical outcomes for metastatic hormone-sensitive prostate cancer (mHSPC), but there are no studies comparing drug efficacies or the influence of racial disparities.

MATERIALS AND METHODS

We performed a retrospective multicenter review from Winship Cancer Institute at Emory University and Georgia Cancer Center for Excellence at Grady Memorial Hospital (2014-2020) for patients with mHSPC treated with either upfront DOC or ABI. Outcomes evaluated were overall survival (OS), progression-free survival (PFS), and prostate-specific antigen complete response (PSA CR).

RESULTS

A total of 168 patients were included, consisting of 92 (54.8%) Black patients and 76 (45.2%) non-Black patients (69 White and 7 Asian or Hispanic). Ninety-four (56%) received DOC and 74 (44%) received ABI. Median follow-up time was 22.8 months with data last reviewed June 2020. For OS, there was no significant difference between ABI versus DOC and Black versus non-Black patients. For PFS, DOC was associated with hazard ratio (HR) 1.7 compared with ABI for all patients based on univariate association and HR 2.27 compared with ABI for Black patients on multivariable analysis. For PSA CR, Black patients were less likely to have a CR (odds ratio [OR] = 0.27).

CONCLUSION

ABI and DOC have similar OS with a trend toward better PFS for ABI in a cohort composed of 54% Black patients. Racial disparities were observed as prolonged PFS for Black patients treated with ABI, more so compared with all patients, and less PSA CR for Black patients. A prospective trial comparing available upfront therapies in a diverse racial population is needed to help guide clinical decision-making in the era of novel treatment options.

IMPLICATIONS FOR PRACTICE

Overall survival is similar for abiraterone and docetaxel when used as upfront therapy in metastatic hormone-sensitive prostate cancer in a cohort composed of 54% Black patients. There is a trend towards improved progression-free survival for abiraterone in all patients and Black patients. Non-Black patients were more likely to achieve prostate-specific antigen (PSA) complete response regardless of upfront therapy.

Phosphorylated LASS2 inhibits prostate carcinogenesis via negative regulation of Wnt/β-catenin signaling

LASS2 is a novel tumor-suppressor gene and has been characterized as a ceramide synthase, which synthesizes very-long acyl chain ceramides. However, LASS2 function and pathway-related activity in prostate carcinogenesis are still largely unexplored. Here, we firstly report that LASS2 promotes β-catenin degradation through physical interaction with STK38, SCYL2, and ATP6V0C via the ubiquitin-proteasome pathway, phosphorylation of LASS2 is essential for β-catenin degradation, and serine residue 248 of LASS2 is illustrated to be a key phosphorylation site. Furthermore, we find that dephosphorylation of LASS2 at serine residue 248 significantly enhances prostate cancer cell growth and metastasis in vivo, indicating that phosphorylated LASS2 inhibits prostate carcinogenesis through negative regulation of Wnt/β-catenin signaling. Thus, our findings implicate LASS2 as a potential biomarker and therapeutic target of prostate cancer.