Inhibition of the erythropoietin-producing receptor EPHB4 antagonizes androgen receptor overexpression and reduces enzalutamide resistance

Artesunate enhances the efficacy of enzalutamide in advanced prostate cancer

Prostate cancer (PCa) is one of the leading causes of death among men worldwide. Treatments targeting the androgen receptor pathway remain the standard therapy for PCa patients. Enzalutamide (ENZ), a second-generation androgen receptor inhibitor, was developed to treat castration-resistant prostate cancer. However, while patients initially respond to ENZ, drug resistance typically develops within a few months. Artesunate (ART), a semisynthetic derivative of the Artemisinin plant, is approved for antimalaria treatment. In this study, we conducted an FDA-approved drug screening and identified ART as a potential candidate for overcoming ENZ resistance in PCa. Mechanistically, ART induces the degradation of c-Myc, enhancing the efficacy of ENZ. Additionally, patient dataset analysis revealed that c-Myc plays a significant role in developing ENZ resistance. To summarize, these findings suggest a novel therapeutic strategy for ENZ-resistant prostate cancer.

Inhibition of EphB4 Receptor Signaling by Ephrin-B2-Competitive and Non-Competitive DARPins Prevents Angiogenesis

The receptor tyrosine kinase EphB4 is involved in tumor angiogenesis, proliferation, and metastasis. Designed ankyrin repeat proteins (DARPins) binding to the EphB4 extracellular domain were identified from a combinatorial library using phage display. Surface plasmon resonance (SPR) allowed us to distinguish between DARPins that either compete with the EphB4 ligand ephrin-B2 for binding to a common site or target a different epitope. The identified DARPins all prevent ligand-induced EphB4 phosphorylation and impair tube formation by endothelial cells in vitro. The competitive DARPin AB1 was additionally shown to inhibit vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF)-induced angiogenesis in vivo. In summary, we have isolated DARPins that exert antiangiogenic effects by specifically binding to EphB4 and may potentially lead to new cancer therapeutics.

CPMKG: a condition-based knowledge graph for precision medicine

Personalized medicine tailors treatments and dosages based on a patient's unique characteristics, particularly its genetic profile. Over the decades, stratified research and clinical trials have uncovered crucial drug-related information-such as dosage, effectiveness, and side effects-affecting specific individuals with particular genetic backgrounds. This genetic-specific knowledge, characterized by complex multirelationships and conditions, cannot be adequately represented or stored in conventional knowledge systems. To address these challenges, we developed CPMKG, a condition-based platform that enables comprehensive knowledge representation. Through information extraction and meticulous curation, we compiled 307 614 knowledge entries, encompassing thousands of drugs, diseases, phenotypes (complications/side effects), genes, and genomic variations across four key categories: drug side effects, drug sensitivity, drug mechanisms, and drug indications. CPMKG facilitates drug-centric exploration and enables condition-based multiknowledge inference, accelerating knowledge discovery through three pivotal applications. To enhance user experience, we seamlessly integrated a sophisticated large language model that provides textual interpretations for each subgraph, bridging the gap between structured graphs and language expressions. With its comprehensive knowledge graph and user-centric applications, CPMKG serves as a valuable resource for clinical research, offering drug information tailored to personalized genetic profiles, syndromes, and phenotypes. Database URL: https://www.biosino.org/cpmkg/.

Identifying Key Genes as Progression Indicators of Prostate Cancer with Castration Resistance Based on Dynamic Network Biomarker Algorithm and Weighted Gene Correlation Network Analysis

Background: Androgen deprivation therapy (ADT) is the mainstay of treatment for prostate cancer, yet dynamic molecular changes from hormone-sensitive to castration-resistant states in patients treated with ADT remain unclear. Methods: In this study, we combined the dynamic network biomarker (DNB) method and the weighted gene co-expression network analysis (WGCNA) to identify key genes associated with the progression to a castration-resistant state in prostate cancer via the integration of single-cell and bulk RNA sequencing data. Based on the gene expression profiles of CRPC in the GEO dataset, the DNB method was used to clarify the condition of epithelial cells and find out the most significant transition signal DNB modules and genes included. Then, we calculated gene modules associated with the clinical phenotype stage based on the WGCNA. IHC was conducted to validate the expression of the key genes in CRPC and primary PCa patients Results:Nomograms, calibration plots, and ROC curves were applied to evaluate the good prognostic accuracy of the risk prediction model. Results: By combining single-cell RNA sequence data and bulk RNA sequence data, we identified a set of DNBs, whose roles involved in androgen-associated activities indicated the signals of a prostate cancer cell transition from an androgen-dependent state to a castration-resistant state. In addition, a risk prediction model including the risk score of four key genes (SCD, NARS2, ALDH1A1, and NFXL1) and other clinical-pathological characteristics was constructed and verified to be able to reasonably predict the prognosis of patients receiving ADT. Conclusions: In summary, four key genes from DNBs were identified as potential diagnostic markers for patients treated with ADT and a risk score-based nomogram will facilitate precise prognosis prediction and individualized therapeutic interventions of CRPC.

Eph receptors and ephrins in cancer progression

Evidence implicating Eph receptor tyrosine kinases and their ephrin ligands (that together make up the 'Eph system') in cancer development and progression has been accumulating since the discovery of the first Eph receptor approximately 35 years ago. Advances in the past decade and a half have considerably increased the understanding of Eph receptor-ephrin signalling mechanisms in cancer and have uncovered intriguing new roles in cancer progression and drug resistance. This Review focuses mainly on these more recent developments. I provide an update on the different mechanisms of Eph receptor-ephrin-mediated cell-cell communication and cell autonomous signalling, as well as on the interplay of the Eph system with other signalling systems. I further discuss recent advances in elucidating how the Eph system controls tumour expansion, invasiveness and metastasis, supports cancer stem cells, and drives therapy resistance. In addition to functioning within cancer cells, the Eph system also mediates the reciprocal communication between cancer cells and cells of the tumour microenvironment. The involvement of the Eph system in tumour angiogenesis is well established, but recent findings also demonstrate roles in immune cells, cancer-associated fibroblasts and the extracellular matrix. Lastly, I discuss strategies under evaluation for therapeutic targeting of Eph receptors-ephrins in cancer and conclude with an outlook on promising future research directions.

A Phase II Study of sEphB4-HSA in Metastatic Castration-Resistant Prostate Cancer

INTRODUCTION

Ephrin receptors and their membrane-localized ligands induce bidirectional signaling and facilitate tumor-stroma interactions. Blocking the EphB4-EphrinB2 pathway, which can be accomplished by soluble EphB4 conjugated to human serum albumin (sEphB4-HSA), promotes cell death in preclinical models of aggressive prostate cancer. We hypothesized that targeting the EphB4-EphrinB2 pathway may serve as a therapeutic target in the treatment of metastatic castration resistant prostate cancer (mCRPC).

PATIENTS AND METHODS

We conducted a single arm, phase II trial in patients with progressive mCRPC who had received no more than 3 prior therapies for mCRPC. sEphB4-HSA 1000 mg IV was administered every 2 weeks, extending to 3 weeks starting from cycle 7. The primary endpoint was confirmed prostate specific antigen (PSA) response rate. We employed a Simon 2-stage Minimax design with 15 patients in the first stage and 10 additional patients in the second stage.

RESULTS

Fourteen eligible patients enrolled in the study with median age of 73.5 years (range: 52-83) and median baseline PSA of 65.11 ng/mL (range: 7.77-2850 ng/mL). Most patients received 3 prior therapies for mCRPC. The median treatment duration with sEphB4-HSA was 6.5 weeks (range: 2-35 weeks). Three patients experienced a serious adverse event potentially related to therapy, including 1 patient with a grade 5 event (cerebral vascular accident) possibly related to the study drug. No patient had a confirmed PSA response, and the study was stopped for futility. Thirteen patients had PSA progression. The median time to PSA progression was 28 days (90% CI: 28-42 days), and median time to radiologic progression was 55 days (90% CI: 54-72 days). Of 3 patients with measurable disease, 2 had stable disease and one had progressive disease.

CONCLUSION

In patients with mCRPC who progressed on prior second generation AR-targeted therapy, sEphB4-HSA monotherapy had no discernable anti-tumor activity.

GSTM2 is a key molecular determinant of resistance to SG-ARIs

Prostate cancer (PCa) continues to threaten men's health, and treatment targeting the androgen receptor (AR) pathway is the major therapy for PCa patients. Several second-generation androgen receptor inhibitors (SG-ARIs), including enzalutamide (ENZ), apalutamide (APA) and darolutamide (DARO), have been developed to better block the activity of AR. Unavoidably, emergence of resistance to these novel drugs still persists. Herein, we identified glutathione S-transferase Mu 2 (GSTM2) as an important determinant in the acquisition of resistance to SG-ARIs. Elevated GSTM2 was detected in enzalutamide-resistant (ENZ-R) PCa, and overexpression of GSTM2 in naïve enzalutamide-sensitive (ENZ-S) cells effectively transformed them to ENZ-R PCa. Aryl hydrocarbon receptor (AhR), the upstream transcription factor, was implicated in the overexpression of GSTM2 in ENZ-R cells. Mechanistically, GSTM2 antagonized the effect of ENZ by rescuing cells from oxidative stress-associated damage and activation of p38 MAPK pathway. Surprisingly, high GSTM2 levels also associated with cross-resistance to APA and DARO. Taking together, these results provide new insight to ameliorate resistance to SG-ARIs and improve treatment outcome.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mechanisms of Resistance to Second-Generation Antiandrogen Therapy for Prostate Cancer: Actual Knowledge and Perspectives

Prostate cancer therapy for locally advanced and metastatic diseases includes androgen deprivation therapy (ADT). Second-generation antiandrogens have a role in castration-resistant prostate cancer. Nevertheless, some patients do not respond to this therapy, and eventually all the patients became resistant. This is due to modifications to intracellular signaling pathways, genomic alteration, cytokines production, metabolic switches, constitutional receptor activation, overexpression of some proteins, and regulation of gene expression. The aim of this review is to define the most important mechanisms that drive this resistance and the newest discoveries in this field, specifically for enzalutamide and abiraterone, with potential implications for future therapeutic targets. Furthermore, apalutamide and darolutamide share some resistance mechanisms with abiraterone and enzalutamide and could be useful in some resistance settings.

Mechanisms of enzalutamide resistance in castration-resistant prostate cancer and therapeutic strategies to overcome it

Prostate cancer is the second most common malignancy in men and androgen deprivation therapy is the first-line therapy. However, most cases will eventually develop castration-resistant prostate cancer after androgen deprivation therapy treatment. Enzalutamide is a second-generation androgen receptor antagonist approved by the Food and Drug Administration to treat patients with castration-resistant prostate cancer. Unfortunately, patients receiving enzalutamide treatment will ultimately develop resistance via various complicated mechanisms. This review examines the emerging information on these resistance mechanisms, including androgen receptor-related signalling pathways, glucocorticoid receptor-related pathways and metabolic effects. Notably, lineage plasticity and phenotype switching, gene polymorphisms and the relationship between microRNAs and drug resistance are addressed. Furthermore, potential therapeutic strategies for enzalutamide-resistant castration-resistant prostate cancer treatment are suggested, which can help discover more effective and specific regimens to overcome enzalutamide resistance.

The Pyrazolo[3,4-d]pyrimidine-Based Kinase Inhibitor NVP-BHG712: Effects of Regioisomers on Tumor Growth, Perfusion, and Hypoxia in EphB4-Positive A375 Melanoma Xenografts

In a previous study, EphB4 was demonstrated to be a positive regulator of A375-melanoma growth but a negative regulator of tumor vascularization and perfusion. To distinguish between EphB4 forward and ephrinB2 reverse signaling, we used the commercially available EphB4 kinase inhibitor NVP-BHG712 (NVP), which was later identified as its regioisomer NVPiso. Since there have been reported significant differences between the inhibition profiles of NVP and NVPiso, we compared the influence of NVP and NVPiso on tumor characteristics under the same experimental conditions. Despite the different inhibitory profiles of NVP and NVPiso, the comparative study conducted here showed the same EphB4-induced effects in vivo as in the previous investigation. This confirmed the conclusion that EphB4-ephrinB2 reverse signaling is responsible for increased tumor growth as well as decreased tumor vascularization and perfusion. These results are further substantiated by microarrays showing differences between mock-transfected and EphB4-transfected (A375-EphB4) cells with respect to at least 9 angiogenesis-related proteins. Decreased expression of vascular endothelial growth factor (VEGF), angiotensin 1 (Ang-1), and protein kinase B (Akt/PKB), together with the increased expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) and transforming growth factor beta-2 (TGF-β2), is consistent with the impaired vascularization of A375-EphB4 xenografts. Functional overexpression of EphB4 in A375-EphB4 cells was confirmed by activation of a variety of signaling pathways, including the Janus kinase/signal transducers and activators of transcription (JAK/STAT), rat sarcoma virus/rapidly accelerated fibrosarcoma/mitogen activated protein kinase kinase (Ras/Raf/MEK), and nuclear factor kappa-B (NFkB) pathways.