Prostate cancer-derived small extracellular vesicle proteins: the hope in diagnosis, prognosis, and therapeutics

Liquid biomarkers in prostate cancer: recent advancements and future directions

PURPOSE OF REVIEW

Traditional diagnostic approaches of prostate cancer like PSA are limited by high false-positive rates and insufficient capture of tumour heterogeneity, necessitating the development of more precise tools. This review examines the latest advancements in liquid biomarkers for prostate cancer, focusing on their potential to refine diagnostic accuracy and monitor disease progression.

RECENT FINDINGS

Liquid biomarkers have gained prominence because of their minimally invasive nature and ability to reflect the molecular characteristics of prostate cancer. Circulating tumour cells provide insight into tumour cell dissemination and are indicative of aggressive disease phenotypes, with single-cell analyses revealing genomic instability and treatment resistance. Circulating tumour DNA offers real-time tumour genomic information, aiding in treatment decision-making in advanced prostate cancer, where it has been associated with clinical progression. MicroRNAs act as oncogenes or tumour suppressors and exhibit diagnostic and prognostic potential; however, their clinical utility is constrained by the lack of consistent validation. Extracellular vesicles contain tumour-derived biomolecules, with specific proteins demonstrating prognostic relevance. Applications of these markers to urinary testing have been demonstrated.

SUMMARY

Liquid biomarkers show potential in refining prostate cancer management. Future research should aim to integrate these biomarkers into a cohesive framework in line with precision medicine principles.

Exosome-delivered NR2F1-AS1 and NR2F1 drive phenotypic transition from dormancy to proliferation in treatment-resistant prostate cancer via stabilizing hormonal receptors

Cancer cells acquire the ability to reprogram their phenotype in response to targeted therapies, yet the transition from dormancy to proliferation in drug-resistant cancers remains poorly understood. In prostate cancer, we utilized high-plasticity mouse models and enzalutamide-resistant (ENZ-R) cellular models to elucidate NR2F1 as a key factor in lineage transition and ENZ resistance. Depletion of NR2F1 drives ENZ-R cells into a relative dormancy state, characterized by reduced proliferation and heightened drug resistance, while NR2F1 overexpression yields contrasting outcomes. Transcriptional sequencing analysis of NR2F1-silenced prostate cancer cells and tissues from the Cancer Genome Atlas-prostate cancer and SU2C cohorts indicated exosomes as the most enriched cell component, with pathways implicated in steroid hormone biosynthesis and drug metabolism. Moreover, NR2F1-AS1 forms a complex with SRSF1 to upregulate NR2F1 expression, facilitating its binding with ESR1 to sustain hormonal receptor expression and enhance proliferation in ENZ-R cells. Furthermore, HnRNPA2B1 interacts with NR2F1 and NR2F1-AS1, assisting their packaging into exosomes, wherein exosomal NR2F1 and NR2F1-AS1 promote the proliferation of dormant ENZ-R cells. Our works offer novel insights into the reawaking of dormant drug-resistant cancer cells governed by NR2F1 upregulation triggered by exosome-derived NR2F1-AS1 and NR2F1, suggesting therapeutic potential for phenotype reversal.

One-Pot Sequential Enrichment of Urinary Extracellular Vesicle and miRNAs Identifies a Noninvasive Biomarker Panel for Prostate Cancer Diagnosis

Extracellular vesicles (EVs) offer promising noninvasive alternatives for convenient and noninvasive prostate cancer (PCa) diagnosis, but inefficient EV enrichment and cargo extraction hinder discovery and validation for their clinical applications. Here, we present an integrated pipeline based on functionalized magnetic beads to streamline and enhance the efficiency of urinary EV miRNA analysis. EVs are first enriched on amphiphilic magnetic beads through chemical affinity, followed by EV lysis and the isolation of miRNAs through solid phase extraction. The new pipeline demonstrated a more than 10-fold increase in urine EV miRNA extraction efficiency compared to the traditional ultracentrifugation combined TRIzol method while reducing the sample processing time to within 1 h. The one-bead strategy further allowed us to automate the procedure on a 96-channel instrument. We applied the pipeline to analyze urine samples from 108 benign prostatic hyperplasia (BPH) controls and 92 PCa cases. Among 195 miRNA biomarkers from the literature, we prioritized 18 miRNAs for quantification and successfully validated 12 miRNAs with a ratio-based normalized method. The quantification data from BPH controls and PCa cases in the training set were subjected to a machine learning analysis of Random Forest, through which we generated a five-miRNA panel consisting of miR-148a-5p, miR-21-5p, miR-181a-5p, miR-222-3p, and miR-100-5p. This panel showed high sensitivity (89%) and specificity (72%) in the test set, highlighting immense potential of this streamlined pipeline for noninvasive diagnosis.

Programmed death receptor (PD-)1/PD-ligand (L)1 in urological cancers : the "all-around warrior" in immunotherapy

Programmed death receptor-1 (PD-1) and its ligand, programmed death ligand-1 (PD-L1) are essential molecules that are key in modulating immune responses. PD-L1 is constitutively expressed on various immune cells, epithelial cells, and cancer cells, where it functions as a co-stimulatory molecule capable of impairing T-cell mediated immune responses. Upon binding to PD-1 on activated T-cells, the PD-1/PD-L1 interaction triggers signaling pathways that can induce T-cell apoptosis or anergy, thereby facilitating the immune escape of tumors. In urological cancers, including bladder cancer (BCa), renal cell carcinoma (RCC), and prostate cancer (PCa), the upregulation of PD-L1 has been demonstrated. It is linked to poor prognosis and enhanced tumor immune evasion. Recent studies have highlighted the significant role of the PD-1/PD-L1 axis in the immune escape mechanisms of urological cancers. The interaction between PD-L1 and PD-1 on T-cells further contributes to immunosuppression by inhibiting T-cell activation and proliferation. Clinical applications of PD-1/PD-L1 checkpoint inhibitors have shown promising efficacy in treating advanced urological cancers, significantly improving patient outcomes. However, resistance to these therapies, either intrinsic or acquired, remains a significant challenge. This review aims to provide a comprehensive overview of the role of the PD-1/PD-L1 signaling pathway in urological cancers. We summarize the regulatory mechanism underlying PD-1 and PD-L1 expression and activity, including genetic, epigenetic, post-transcriptional, and post-translational modifications. Additionally, we discuss current clinical research on PD-1/PD-L1 inhibitors, their therapeutic potential, and the challenges associated with resistance. Understanding these mechanisms is crucial for developing new strategies to overcome therapeutic limitations and enhance the efficacy of cancer immunotherapy.

Extracellular vesicles and the "six Rs" in radiotherapy

Over half of patients with cancer receive radiation therapy during the course of their disease. Decades of radiobiological research have identified 6 parameters affecting the biological response to radiation referred to as the 6 "Rs": Repair, Radiosensitivity, Repopulation, Redistribution, Reoxygenation, and Reactivation of the anti-tumour immune response. Extracellular Vesicles (EVs) are small membrane-bound particles whose multiple biological functions are increasingly documented. Here we discuss the evidence for a role of EVs in the orchestration of the response of cancer cells to radiotherapy. We highlight that EVs are involved in DNA repair mechanisms, modulation of cellular sensitivity to radiation, and facilitation of tumour repopulation. Moreover, EVs influence tumour reoxygenation dynamics, and play a pivotal role in fostering radioresistance. Last, we examine how EV-related strategies could be translated into novel strategies aimed at enhancing the efficacy of radiation therapy against cancer.

Cellular senescence in metastatic prostate cancer: A therapeutic opportunity or challenge (Review)

The treatment of patients with metastatic prostate cancer (PCa) is considered to be a long‑standing challenge. Conventional treatments for metastatic PCa, such as radical prostatectomy, radiotherapy and androgen receptor‑targeted therapy, induce senescence of PCa cells to a certain extent. While senescent cells can impede tumor growth through the restriction of cell proliferation and increasing immune clearance, the senescent microenvironment may concurrently stimulate the secretion of a senescence‑associated secretory phenotype and diminish immune cell function, which promotes PCa recurrence and metastasis. Resistance to established therapies is the primary obstacle in treating metastatic PCa as it can lead to progression towards an incurable state of disease. Therefore, understanding the molecular mechanisms that underly the progression of PCa is crucial for the development of novel therapeutic approaches. The present study reviews the phenomenon of treatment‑induced senescence in PCa, the dual role of senescence in PCa treatments and the mechanisms through which senescence promotes PCa metastasis. Furthermore, the present review discusses potential therapeutic strategies to target the aforementioned processes with the aim of providing insights into the evolving therapeutic landscape for the treatment of metastatic PCa.

Role of extracellular vesicles in castration-resistant prostate cancer

Prostate cancer (PCa) is a common health threat to men worldwide, and castration-resistant PCa (CRPC) is the leading cause of PCa-related deaths. Extracellular vesicles (EVs) are lipid bilayer compartments secreted by living cells that are important mediators of intercellular communication. EVs regulate the biological processes of recipient cells by transmitting heterogeneous cargoes, contributing to CRPC occurrence, progression, and drug resistance. These EVs originate not only from malignant cells, but also from various cell types within the tumor microenvironment. EVs are widely dispersed throughout diverse biological fluids and are attractive biomarkers derived from noninvasive liquid biopsy techniques. EV quantities and cargoes have been tested as potential biomarkers for CRPC diagnosis, progression, drug resistance, and prognosis; however, technical barriers to their clinical application continue to exist. Furthermore, exogenous EVs may provide tools for new therapies for CRPC. This review summarizes the current evidence on the role of EVs in CRPC.

Identification of cell differentiation trajectory-related gene signature to reveal the prognostic significance and immune landscape in prostate cancer based on multiomics analysis

Background

In the context of prostate cancer (PCa), the occurrence of biochemical recurrence (BCR) stands out as a pivotal factor significantly impacting prognosis, potentially leading to metastasis and mortality. However, the early detection of BCR poses a substantial challenge for PCa patients. There is an urgent need to pinpoint hub genes that can serve as predictive indicators for BCR in PCa patients.

Methods

Our primary goal was to identify cell differentiation trajectory-related gene signature in PCa patients by pseudo-time trajectory analysis. We further explored the functional enrichment of overlapped marker genes and probed clinically relevant modules and BCR-related genes using Weighted Gene Co-expression Network Analysis (WGCNA) in PCa patients. Key genes predicting recurrence-free survival were meticulously identified through univariate and multivariate Cox regression analyses. Subsequently, these genes were utilized to construct a prognostic gene signature, the expression, predictive efficacy, putative functions, and immunological landscape of which were thoroughly validated. Additionally, we employed immunohistochemistry (IHC) and a western blotting assay to quantify the expression of PYCR1 in clinical samples.

Results

Our single-cell RNA (scRNA) sequencing analysis unveiled three subgroups characterized by distinct differentiation trajectories, and the marker genes associated with these groups were extracted from PCa patients. These marker genes successfully classified the PCa sample into two molecular subtypes, demonstrating a robust correlation with clinical characteristics and recurrence-free survival. Through WGCNA and Lasso analysis, we identified four hub genes (KLK3, CD38, FASN, and PYCR1) to construct a risk profile of prognostic genes linked to BCR. Notably, the high-risk patient group exhibited elevated levels of B cell naive, Macrophage M0, and Macrophage M2 infiltration, while the low-risk group displayed higher levels of T cells CD4 memory activated and monocyte infiltration. Furthermore, IHC and western blotting assays confirmed the heightened expression of PYCR1 in PCa tissues.

Conclusion

This study leveraged the differentiation trajectory and genetic variability of the microenvironment to uncover crucial prognostic genes associated with BCR in PCa patients. These findings present novel perspectives for tailoring treatment strategies for PCa patients on an individualized basis.

Research progress of CTC, ctDNA, and EVs in cancer liquid biopsy

Circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and extracellular vehicles (EVs) have received significant attention in recent times as emerging biomarkers and subjects of transformational studies. The three main branches of liquid biopsy have evolved from the three primary tumor liquid biopsy detection targets-CTC, ctDNA, and EVs-each with distinct benefits. CTCs are derived from circulating cancer cells from the original tumor or metastases and may display global features of the tumor. ctDNA has been extensively analyzed and has been used to aid in the diagnosis, treatment, and prognosis of neoplastic diseases. EVs contain tumor-derived material such as DNA, RNA, proteins, lipids, sugar structures, and metabolites. The three provide different detection contents but have strong complementarity to a certain extent. Even though they have already been employed in several clinical trials, the clinical utility of three biomarkers is still being studied, with promising initial findings. This review thoroughly overviews established and emerging technologies for the isolation, characterization, and content detection of CTC, ctDNA, and EVs. Also discussed were the most recent developments in the study of potential liquid biopsy biomarkers for cancer diagnosis, therapeutic monitoring, and prognosis prediction. These included CTC, ctDNA, and EVs. Finally, the potential and challenges of employing liquid biopsy based on CTC, ctDNA, and EVs for precision medicine were evaluated.