Targets

Colorectal, lung, breast, and melanoma malignancies remain major contributors to cancer-related morbidity and mortality worldwide, underscoring the need for therapeutic strategies that can be rapidly translated to the clinic. Drug repurposing offers an attractive route for accelerating oncology drug development, particularly for agents with established safety profiles. Niclosamide, an FDA-approved anthelmintic, has demonstrated broad anticancer activity through modulation of Wnt1/β-catenin signaling and other pathways associated with tumor growth, metastasis, and therapeutic resistance. However, poor pharmaceutical and pharmacokinetic properties have limited its advancement as a systemic cancer therapeutic. To investigate prodrug-based approaches for improving niclosamide delivery, we synthesized a panel of ester and carbonate derivatives bearing structurally diverse alkyl promoieties and evaluated their hydrolytic stability, anticancer activity, and drug-like properties through experimental and in silico analyses. Antiproliferative activity was assessed across a diverse panel of human and murine cancer models, including colorectal (HCT-116, HT-29), lung (A549), breast (MDA-MB-231), and melanoma (B16F10) cell lines. All derivatives underwent rapid hydrolysis under an organics rich autohydrolysis assay, efficiently regenerating niclosamide. While alkyl substitution produced modest differences in hydrolytic stability, these variations did not substantially influence anticancer activity, with the prodrugs displaying comparable potency profiles across the evaluated cancer models. In silico pharmacokinetic and drug metabolism analyses further suggested that prodrug derivatization may offer opportunities to modulate developability while preserving pharmacological activity through rapid bioactivation. Collectively, these findings establish ester and carbonate derivatization as a viable therapeutic delivery strategy for niclosamide and provide a framework for the continued development of niclosamide-based cancer therapeutics with improved pharmaceutical properties and retained anticancer efficacy.

Microglia are key regulators of central nervous system homeostasis and neuroinflammation, and cannabinoid type 2 receptors (CB₂Rs) have emerged as important modulators of microglial function. Although the pharmacology of CB₂Rs has been extensively characterised in heterologous expression systems and activated microglia, comparatively little is known about the behaviour of CB₂R ligands in non-stimulated microglia. The present study therefore aimed to characterise the pharmacological properties of a panel of CB₂R ligands in non-stimulated BV-2 microglial cells and to determine whether constitutive receptor activity and ligand-dependent signalling bias could be detected under basal conditions. Classical CB₂R agonists (CP 55,940, WIN 55,212-2, JWH 133 and JWH 015), putative protean agonists ((R)-AM 1241 and GW 405833), and inverse agonists (SR 144528, AM 630 and JTE 907) were evaluated using [³⁵S]GTPγS binding and forskolin-stimulated cAMP assays. In the [³⁵S]GTPγS assay, WIN 55,212-2 displayed the highest intrinsic activity, whereas (R)-AM 1241 and GW 405833 behaved as partial agonists. Inverse agonists reduced basal signalling, indicating constitutive CB₂R activity in resting BV-2 cells. In contrast, cAMP measurements revealed greater signal amplification, with (R)-AM 1241 and GW 405833 exhibiting full agonist behaviour and SR 144528 producing pronounced inverse agonism. Marked differences in ligand efficacy and rank order between assays highlighted the influence of downstream signalling mechanisms and ligand-dependent signalling bias. Notably, GW 405833 displayed a strongly biased signalling profile, whereas SR 144528 consistently exhibited the greatest inverse agonist activity. These findings demonstrate that CB₂Rs are functionally active in non-stimulated microglia and that constitutive receptor activity and signalling bias contribute significantly to their pharmacological profile under basal conditions. By focusing on non-stimulated microglia, this study provides new insights into CB₂R signalling in a homeostatic cellular environment and establishes a framework for understanding how CB₂R pharmacology may be altered during neuroinflammatory and neurodegenerative disease states.

Small extracellular vesicles (sEVs) are pivotal mediators of intercellular epigenetic communication in cancer. Following MISEV2023, we use the size- and isolation-based term sEV throughout, because most primary studies cited here cannot resolve which biogenetic route generated the vesicles they analyzed. By selectively packaging and transferring noncoding RNAs (ncRNAs), DNA fragments, chromatin-modifying enzymes, and metabolic effectors, sEVs reprogram recipient-cell chromatin architecture without altering the underlying DNA sequence. Tumor-derived sEVs engage stromal, immune, and vascular compartments to drive malignant progression through mechanisms that include miRNA-directed suppression of DNA methyltransferases (DNMTs), lncRNA-scaffolded Polycomb Repressive Complex 2 (PRC2) recruitment, depositing H3K27me3, and oncometabolite-mediated inhibition of TET dioxygenases. This narrative review synthesizes mechanistic, preclinical, and translational evidence on sEV-driven epigenetic regulation in cancer, applies a four-level evidence hierarchy to calibrate mechanistic claims, and critically evaluates how distinct cargo classes–microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), DNMTs, and histone-modifying enzymes–contribute to chromatin remodeling, aberrant DNA methylation, acquired therapy resistance, and immune evasion in recipient cells. We further examine sEV cargo signatures as minimally invasive liquid biopsy biomarkers and appraise engineered sEV platforms for the precision delivery of miRNA mimics, siRNAs, and small-molecule epigenetic inhibitors. Key methodological challenges, EV isolation standardization, MISEV2023 compliance, cargo stoichiometry at physiological concentrations, in vivo biodistribution, and the transition from post-transcriptional regulation to durable chromatin-state change are critically evaluated, and a translational roadmap is proposed to guide reproducible clinical implementation of sEV-mediated epigenetic cancer therapeutics.