Exosomes are secreted at similar densities by M21 and PC3 human cancer cells and show paclitaxel solubility

Acidic Conditions Promote Clustering of Cancer Cell Derived Extracellular Vesicles and Enhance their Fusion with Synthetic Liposomes

Extracellular vesicles (EVs) are endogenous vesicles secreted by cells. Exosomes (30-150 nm), are a subset of EVs playing key roles in intercellular communication. Exosomes show promise as cancer chemotherapeutic drug delivery vehicles given their low immunogenicity and cell-specific cytosolic delivery of their contents. However, inefficient drug loading limits their therapeutic application. To address this, methods for the fusion of EVs with therapeutic drug-loaded synthetic liposomes have been developed. While more efficient than passive incubation of EVs with liposomes, these risk either damage to EV membrane proteins or contamination of the EV-liposome hybrids with residual depletant molecules, which can cause side effects or hinder content delivery. Here, we present a new, weakly perturbative method, which uses acidic conditions (pH 5) to enhance the fusion of EVs and synthetic, neutral liposomes (NLs) compared to passive incubation in pH 7.4 at 37 °C. An adapted Forster resonance energy transfer (FRET) based lipid mixing assay confirms that fusion is enhanced with this method, albeit less efficiently than with depletant-induced fusion. This significant finding implies that lipid-only synthetic liposomes can fuse with EVs, creating EV-liposome hybrids under relevant temperature and pH conditions, without nonlipidic components, such as fusogenic amphipathic peptides, added to the synthetic liposomes. Remarkably, differential interference contrast (DIC) and fluorescence microscopy show that this enhanced fusion corresponds with the clustering of mixtures of EVs and NLs, or EVs alone, in acidic but not neutral pH conditions. The findings support a hypothesis that content release from EVs in early to late endocytic environments may be a combination of protein-protein clustering interactions and a lipidic component. Further, this study provides a novel method for enhanced fusion of EVs and liposomes, which is expected to preserve EV membrane proteins and functionality toward the development of therapeutic hybrid drug delivery vehicles in nanomedicine applications.

Extracellular Vesicles as Mediators and Potential Targets in Combating Cancer Drug Resistance

Extracellular vesicles (EVs) are key mediators in the communication between cancer cells and their microenvironment, significantly influencing drug resistance. This review provides a comprehensive analysis of the roles of EVs in promoting drug resistance through mechanisms such as drug efflux, apoptosis resistance, autophagy imbalance, and tumor microenvironment modulation. Despite extensive research, details of EVs biogenesis, cargo selection, and specific pathways in EVs-mediated drug resistance are not fully understood. This review critically examines recent advancements, highlighting key studies that elucidate the molecular mechanisms of EVs functions. Additionally, innovative therapeutic strategies targeting EVs are explored, including inhibiting EVs biogenesis, engineering EVs for drug delivery, and identifying resistance-inhibiting molecules within EVs. By integrating insights from primary research and proposing new directions for future studies, this review aims to advance the understanding of EVs in cancer biology and foster effective interventions to mitigate drug resistance in cancer therapy.

Characterisation of Castration-Resistant Cell-Derived Exosomes and Their Effect on the Metastatic Phenotype

BACKGROUND/OBJECTIVES

Prostate cancer (PCa) is characterised by its progression to a metastatic and castration-resistant phase. Prostate tumour cells release small extracellular vesicles or exosomes which are taken up by target cells and can potentially facilitate tumour growth and metastasis. The present work studies the effect of exosomes from cell lines that are representative of the different stages of the disease on the tumoral phenotype of PC3 cells.

METHODS

Exosomes were isolated by ultracentrifugation from human prostate epithelial cells (RWPE-1) and androgen-dependent PCa cells (LNCaP) and castration-resistant PCa cells (CRPC) with moderate (DU145) or high (PC3) metastatic capacity. The biophysical and biochemical properties of the exosomes were characterised as well as their effects on PC3 cell viability and migration.

RESULTS

The study of the exosomes of prostate cell lines shows heterogeneity in their size, presenting in some of them two types of populations; in both populations, a larger size in those derived from PC3 cells and a smaller size in those derived from non-tumourigenic prostate cells were detected. Differences were found in the physical properties of those derived from healthy and PCa cells, as well as between cells representative of the most aggressive stages of the disease. The highest gamma-glutamyl transferase (GGT) activity was observed in androgen-dependent cells and differences in the pro-metalloproteinases (MMP) activity were detected in healthy cells and in castration-resistant cells with moderate metastatic capacity with respect to PC3 cells. The treatment of PC3 cells with their own exosomes increased PC3 cell viability and migration.

CONCLUSION

Exosomes represent a promising field of research in the diagnosis, prognosis, and treatment of prostate cancer.

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.

A comprehensive review of challenges and advances in exosome-based drug delivery systems

Exosomes or so-called natural nanoparticles have recently shown enormous potential for targeted drug delivery systems. Several studies have reported that exosomes as advanced drug delivery platforms offer efficient targeting of chemotherapeutics compared to individual polymeric nanoparticles or liposomes. Taking structural constituents of exosomes, viz., proteins, nucleic acids, and lipids, into consideration, exosomes are the most promising carriers as genetic messengers and for treating genetic deficiencies or tumor progression. Unfortunately, very little attention has been paid to the factors like source, scalability, stability, and validation that contribute to the quality attributes of exosome-based drug products. Some studies suggested that exosomes were stable at around -80 °C, which is impractical for storing pharmaceutical products. Currently, no reports on the shelf-life and in vivo stability of exosome formulations are available. Exosomes are quickly cleared from blood circulation, and their in vivo distribution depends on the source. Considering these challenges, further studies are necessary to address major limitations such as poor drug loading, reduced in vivo stability, a need for robust, economical, and scalable production methods, etc., which may unlock the potential of exosomes in clinical applications. A few reports based on hybrid exosomes involving hybridization between different cell/tumor/macrophage-derived exosomes with synthetic liposomes through membrane fusion have shown to overcome some limitations associated with natural or synthetic exosomes. Yet, sufficient evidence is indispensable to prove their stability and clinical efficacy.

Exosome-like Nanoparticles, High in Trans-δ-Viniferin Derivatives, Produced from Grape Cell Cultures: Preparation, Characterization, and Anticancer Properties

Background: Recent interest in plant-derived exosome-like nanoparticles (ENs) has surged due to their therapeutic potential, which includes antioxidant, anti-inflammatory, and anticancer activities. These properties are attributed to their cargo of bioactive metabolites and other endogenous molecules. However, the properties of ENs isolated from plant cell cultures remain less explored. Methods: In this investigation, grape callus-derived ENs (GCENs) were isolated using differential ultracentrifugation techniques. Structural analysis through electron microscopy, nanoparticle tracking analysis, and western blotting confirmed that GCENs qualify as exosome-like nanovesicles. Results: These GCENs contained significant amounts of microRNAs and proteins characteristic of plant-derived ENs, as well as trans-δ-viniferin, a notable stilbenoid known for its health-promoting properties. Functional assays revealed that the GCENs reduced the viability of the triple-negative breast cancer cell line MDA-MB-231 in a dose-dependent manner. Moreover, the GCENs exhibited negligible effects on the viability of normal human embryonic kidney (HEK) 293 cells, indicating selective cytotoxicity. Notably, treatment with these GCENs led to cell cycle arrest in the G1 phase and triggered apoptosis in the MDA-MB-231 cell line. Conclusions: Overall, this study underscores the potential of grape callus-derived nanovectors as natural carriers of stilbenoids and proposes their application as a novel and effective approach in the management of cancer.

Small extracellular vesicles: Roles and clinical application in prostate cancer

Prostate cancer is a significant health problem in the United States. It is remarkably heterogenous, ranging from slow growing disease amenable to active surveillance to highly aggressive forms requiring active treatments. Therefore, being able to precisely determine the nature of disease and appropriately match patients to available and/or novel therapeutics is crucial to improve patients' overall outcome and quality of life. Recently small extracellular vesicles (sEVs), a subset of nanoscale membranous vesicles secreted by various cells, have emerged as important analytes for liquid biopsy and promising vehicles for drug delivery. sEVs contain various biomolecules such as genetic material, proteins, and lipids that recapitulate the characteristics and state of their donor cells. The application of existing and newly developed technologies has resulted in an increased depth of knowledge about biophysical structures, biogenesis, and functions of sEVs. In prostate cancer patients, tumor-derived sEVs can be isolated from biofluids, commonly urine and blood. They mediate intercellular signaling within the tumor microenvironment and distal organ-specific sites, supporting cancer initiation, progression, and metastasis. A mounting body of evidence suggests that sEV components can be potent biomarkers for prostate cancer diagnosis, prognosis, and prediction of disease progression and treatment response. Due to enhanced circulation stability and bio-barrier permeability, sEVs can be also used as effective drug delivery carriers to improve the efficacy and specificity of anti-tumor therapies. This review discusses recent studies on sEVs in prostate cancer and is focused on their role as biomarkers and drug delivery vehicles in the clinical management of prostate cancer.

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

Current diagnostic tools for prostate cancer (PCa) diagnosis and risk stratification are insufficient. The hidden onset and poor efficacy of traditional therapies against metastatic PCa make this disease a heavy burden in global men's health. Prostate cancer-derived extracellular vesicles (PCDEVs) have garnered attention in recent years due to their important role in communications in tumor microenvironment. Recent advancements have demonstrated PCDEVs proteins play an important role in PCa invasion, progression, metastasis, therapeutic resistance, and immune escape. In this review, we briefly discuss the applications of sEV proteins in PCa diagnosis and prognosis in liquid biopsy, focus on the roles of the PCa-derived small EVs (sEVs) proteins in tumor microenvironment associated with cancer progression, and explore the therapeutic potential of sEV proteins applied for future metastatic PCa therapy.