Search Results (10,643)

Sphingolipids, first discovered in 1874 by Johann Thudicum, are among the eight recognized classes of lipids and are present in essentially all plants, animals, and fungi, as well as some viruses and prokaryotes. In mammals, sphingolipids are enriched in the central nervous system (CNS), where they play vital roles in tissue development; membrane structure; cell adhesion and recognition; and, importantly, signaling. A subset of sphingolipids including ceramide, glucosylceramide, and sphingosine has been shown to have bioactive properties, but two sphingolipids in particular (ceramide-1-phosphate and sphingosine-1-phosphate) have been shown to exert their effects at least in part due to the activation of cell surface-expressed G protein-coupled receptors. In the CNS, sphingosine-1-phosphate signaling has specifically emerged as a productive therapeutic target for the treatment of neurodegenerative disease, with the first small molecule targeting sphingosine-1-phosphate receptors approved roughly 15 years ago for the treatment of multiple sclerosis. As more specific activators and inhibitors of these receptors have been developed and entered the clinical trial pipeline, now is an appropriate time to examine the current state of our knowledge of the role that these receptors play in the CNS and highlight the current landscape of available modulators targeting these pathways. Full article

Triple-negative breast cancer (TNBC) remains one of the most aggressive breast cancer subtypes and is associated with limited therapeutic options, underscoring the urgent need for novel treatment strategies. In this study, a library of seventeen 1,3,5-triazine derivatives potentially targeting TNBC was developed using an activity-based approach. Compounds were synthesized via an ultrasound-assisted protocol, providing an efficient and environmentally friendly methodology. The synthesized library was evaluated in vitro against the human TNBC cell lines MDA-MB-468, MDA-MB-231, and Hs578T, as well as the non-tumorigenic epithelial cell line MCF10A. Compounds 9 and 17 exhibited the most promising antiproliferative activity against TNBC cell lines (MDA-MB-468: IC₅₀ = 36.62 µM for 9 and 38.29 µM for 17; MDA-MB-231: IC₅₀ = 37.32 µM for 9 and 32.86 µM for 17; Hs578T: IC₅₀ = 57.26 µM for 9 and 34.87 µM for 17), while maintaining acceptable selectivity toward non-cancerous cells. The lead compounds were further assessed in vivo using a Danio rerio model to evaluate general toxicity and cardiotoxicity. In addition, ADME parameters were predicted for all compounds using biomimetic chromatography. Overall, compounds 9 and 17 emerged as promising small-molecule candidates for TNBC treatment, requiring further toxicological evaluation in more human-relevant in vivo models. Full article

Antimicrobial resistance (AMR) is one of the most pressing global public health challenges, compromising the effectiveness of standard antibiotic therapies and increasing morbidity, mortality, and healthcare costs. The scarcity of new antibiotics has driven research into alternative strategies to restore or enhance the effectiveness of existing drugs. Natural compounds, including polyphenols, alkaloids, terpenes and terpenoids, antimicrobial peptides, and microbial secondary metabolites, exhibit multitarget activities such as membrane disruption, efflux pump inhibition, biofilm suppression, and quorum sensing interference. In parallel, synthetic and semi-synthetic small-molecule inhibitors have been rationally designed to target specific resistance determinants, including β-lactamases, efflux systems, quorum sensing pathways, and stress-induced mutagenesis mechanisms such as the SOS response and DNA repair processes. These agents act as adjuvants, restoring susceptibility or reducing bacterial virulence without exerting strong selective pressure. The integration of natural bioactive compounds and targeted small-molecule inhibitors represents a promising complementary strategy for conventional antibiotics. Further pharmacological and clinical investigations are required to translate these approaches into effective tools within antimicrobial stewardship programs and broader public health strategies aimed at mitigating the global burden of AMR. This narrative review analyses the recent literature on natural compounds and synthetic or semi-synthetic small-molecule inhibitors with documented activity against antimicrobial resistance mechanisms. Full article

Glycogen synthase kinase-3 (GSK3) inhibition is a commonly used approach to promote osteogenic differentiation through activation of Wnt signaling. However, 6-bromoindirubin-3′-oxime (BIO), which is commonly used for GSK3 inhibition, also targets JAK/STAT, raising the possibility of dual pathway interference during osteoblast differentiation, as both GSK3 and JAK/STAT pathways are critical regulators of osteoblastogenesis. In this study, we investigated the effect of BIO on the osteoblast differentiation of hMSCs-TERT4. While BIO had no significant effect on cell viability or apoptosis, it markedly inhibited osteoblast differentiation, as evidenced by reduced ALP activity, decreased matrix mineralization, and downregulation of osteoblast-associated markers. Microarray analysis followed by qRT-PCR validation revealed downregulation of Wnt and TGF-β pathway genes. These findings show that BIO suppresses osteoblast commitment and osteogenic differentiation, accompanied by altered Wnt- and TGF-β-related gene expression. This study provides mechanistic insight into the off-target consequences of widely used small molecules and highlights the importance of dissecting pathway-specific roles in stem cell differentiation. Understanding the interplay between GSK3 and JAK signaling is essential for optimizing pharmacological strategies in skeletal regenerative medicine. This study highlights the importance of pathway selectivity when using small molecules in stem cell-based therapies for bone regeneration. Full article

Background: G_M1-gangliosidosis (G_M1) is a lysosomal storage disorder caused by mutations in the Glb1 gene, resulting in reduced β-galactosidase activity and accumulation of G_M1 gangliosides in neuronal lysosomes. Effective therapeutic strategies for this disease remain limited. Substrate reduction therapy using small molecules targeting glucosylceramide synthase (GCS) and non-lysosomal glucosylceramidase (GBA2), such as sinbaglustat, represents a promising approach. Methods: Structural and electrophysiological properties of principal neurons of the medial nucleus of the trapezoid body (MNTB) were investigated in 7-month-old Glb1^−/− mice. Animals received long-term treatment with either low (LD; 10 mg/kg) or high (HD; 300 mg/kg) doses of sinbaglustat and were compared with untreated Glb1^−/− (KO) and untreated wild-type (WT) mice. Results: Sinbaglustat treatment reduced lysosomal storage material in MNTB neurons. Basal membrane properties were largely unchanged across groups. However, action potential halfwidth was significantly increased in untreated KO and LD mice compared to untreated WT animals but was normalized in HD mice. After-hyperpolarization duration was prolonged in Glb1^−/− mice relative to WT. Temporal precision during high-frequency stimulation was reduced in untreated KO mice and improved following sinbaglustat treatment. Conclusions: These findings indicate that G_M1-gangliosidosis is associated with functional alterations in MNTB neurons and suggest that long-term sinbaglustat treatment can partially restore neuronal electrophysiological properties, supporting its therapeutic potential in G_M1. Full article

Immunotherapy, particularly effective in tumors with a high mutational burden, is very often administered in combination with chemotherapy. Several tumor types with a high mutational rate include melanoma and non-small cell lung cancer (NSCLC), which are particularly sensitive to immunotherapy. For NSCLC, conventional platinum-based doublet chemotherapy has been extended with drugs targeting signaling pathways (such as the epidermal growth factor receptor) and immune checkpoint inhibitors (ICI) directed against PD-1 and PD-L1. This review highlights the potential role of the membrane antigens CD73 and CD39 in enhancing the efficacy of combined immuno-chemotherapy. These ecto-nucleotidases catalyze the degradation of extracellular ATP to AMP and subsequently to adenosine (Ado), a potent immunosuppressive metabolite that acts through adenosine receptors. Consequently, CD73 and CD39 function as key downregulators of immunogenic signaling. Both CD73 and CD39 are highly expressed not only on tumor cells but also on immune and endothelial cells within the tumor microenvironment. Conventional chemotherapy may further upregulate their expression, contributing to drug resistance and impaired immune responses. To counteract these effects, inhibitors of CD73 and CD39, both monoclonal antibodies and small molecules, are currently under clinical evaluation, with early results indicating potential therapeutic benefit. Although this evidence supports the involvement of CD73 and CD39 in modulating responses to immunotherapy, particularly in combination with chemotherapy, the precise mechanisms underlying these interactions remain unclear. Elucidating these pathways will be critical for optimizing treatment strategies and improving clinical outcomes in malignancies such as NSCLC. This review highlights the critical role of these pathways in optimizing treatment strategies and improving clinical outcomes in malignancies such as NSCLC. Full article

Allosteric modulation has emerged as a powerful strategy for achieving superior selectivity and safety in drug discovery and protein function regulation. Unlike highly conserved orthosteric sites, allosteric pockets are structurally diverse and less evolutionarily constrained, making them particularly suitable for modulation by designed miniproteins. Miniproteins can provide extended binding interfaces and high affinity for shallow, dynamic, or cryptic regulatory surfaces that are often inaccessible to small molecules. Recent advances in artificial intelligence (AI) are transforming this field through deep learning-based structure prediction and generative modeling. These AI-driven approaches enable the identification of allosteric hotspots, characterization of conformational ensembles, and de novo design of structured miniprotein binders. They are rapidly expanding the landscape for designing selective modulators across diverse allosteric targets, including GPCRs, receptor tyrosine kinases, nuclear receptors, ion channels, and other protein–protein interaction systems. This review summarizes state-of-the-art AI-driven computational methodologies for designing miniproteins as potential allosteric modulators and discusses their current challenges and future opportunities in allosteric drug discovery. Full article

CRISPR screens are a powerful functional genomics approach for identifying genes that confer sensitivity and resistance to anti-cancer therapies. CFI-402257 (luvixasertib, 2257) is a small molecule inhibitor of threonine tyrosine kinase (TTK), a promising therapeutic target in genomically unstable cancers due to its critical role in establishing the spindle assembly checkpoint (SAC) during mitosis. To inform its ongoing development and evaluation in clinical trials, we sought to use CRISPR activation (i.e., gain of function) screens to identify cellular mechanisms of resistance to 2257 in models of triple-negative breast cancer (TNBC). In vitro screens conducted in two TNBC cell lines nominated ABCG2 as the top resistance-conferring gene in both models. Validation studies assessing clonogenic survival and apoptosis confirmed that ABCG2 overexpression enhanced TNBC resistance to 2257 in vitro, while knockdown enhanced sensitivity. These findings suggest that 2257 is a substrate of ABCG2’s drug efflux activity. However, overexpression of ABCG2 failed to confer resistance to 2257 in TNBC xenografts grown in mice and treated with a moderately active dose and schedule. Our results highlight the potential impact of drug transporters in in vitro CRISPR screens and the importance of confirming the relevance of drug response mechanisms identified in cultured cells using in vivo models that recapitulate drug pharmacokinetics and pharmacodynamics. Full article

Osteosarcoma, the most prevalent primary malignant bone tumor in children and adolescents, is characterized by high rates of metastasis, recurrence, and chemotherapy resistance, leading to suboptimal patient survival. The MDM2-p53 pathway plays a pivotal role in its tumorigenesis and progression, where dysregulation leads to loss of p53 function. This review systematically elucidates the molecular mechanisms of this pathway and summarizes diverse targeted therapeutic strategies, including small-molecule MDM2 inhibitors, mutant p53 reactivators, and innovative modalities such as gene therapy and Proteolysis Targeting Chimeras (PROTACs). Despite demonstrating potent preclinical activity with low IC₅₀ values, the clinical translation of these agents has faced significant challenges. Early-generation MDM2 inhibitors (e.g., RG7112, Idasanutlin) showed limited monotherapy efficacy and dose-limiting toxicities like thrombocytopenia, halting their development at early-phase clinical trials. In contrast, novel MDM2 inhibitors like APG-115 have advanced to Phase II trials, marking a significant breakthrough. Although not yet tested in dedicated osteosarcoma cohorts, their safety and efficacy in MDM2-amplified solid tumors provide a critical foundation for the development of precision medicine and combination regimens for osteosarcoma. Future efforts to accelerate drug development may leverage single-cell sequencing and AI-aided drug design to decipher osteosarcoma heterogeneity and optimize drug profiles for reduced toxicity. Full article

Xeroderma pigmentosum group B (XPB/ERCC3) and group D (XPD/ERCC2) helicases are integral components of the transcription factor IIH (TFIIH) complex, coordinating DNA unwinding during transcription initiation and nucleotide excision repair (NER). XPB functions as an ATP-driven translocase that generates torsional strain to promote promoter melting and DNA opening at lesion sites, whereas XPD acts as a 5′ to 3′ helicase responsible for lesion verification and extension of the repair bubble. Structural and biochemical studies have clarified how TFIIH subunits regulate these helicases—p52 and p8 modulate XPB’s translocation activity, while p44, p62, and MAT1 control XPD’s helicase function through conformational and compositional transitions within the complex. Beyond their canonical roles, XPB and XPD participate in diverse cellular pathways, including cell-cycle regulation and oxidative stress response, highlighting their involvement in maintaining genome integrity beyond repair and transcription. Mutations in either helicase lead to xeroderma pigmentosum (XP), trichothiodystrophy (TTD), or combined XP/Cockayne syndrome (XP/CS) phenotypes, emphasizing the essential role of TFIIH integrity for human health. Recent biochemical and pharmacological advances have further revealed the therapeutic relevance of these helicases—XPB as a target of small-molecule inhibitors such as triptolide, Minnelide, and spironolactone, and XPD as a potential modulator of cancer sensitivity to DNA-damaging treatments. Collectively, XPB and XPD exemplify the structural and functional versatility of TFIIH helicases across repair, transcription, and genome maintenance. Full article

Background: Tumor-derived small extracellular vesicles (sEV), which we call TEX, carry a cargo of molecules that resembles the producer tumor cells. Circulating freely in body fluids, TEX potentially serve as a liquid tumor biopsy. TEX horizontally transfer their cargo to various recipient cells, imparting to them pro-tumor activity. Mechanisms of TEX-driven reprogramming might involve nucleic acids, especially double-stranded (ds)DNA. Methods: TEX isolated from supernatants of human tumor cells were identified as sEV, based on their size, endocytic origin and morphology. TEX treated with DNase/RNase cocktail were examined by transmission and cryo-electron microscopy and tested for biologic activity. DNA was extracted from enzyme-treated TEX, quantified by Qubit and analyzed for fragment sizes. The presence of genomic DNA in TEX was confirmed by PCR, and sequencing of the TP53 gene fragment for a mutational signature was performed. Results: Enzymatic and microscopic studies of TEX showed that nucleic acids are present in the biocorona on the outer surface. Their removal interfered with the biocorona integrity. A short TEX exposure to DNase/RNase altered their morphology without impairing vesicle functions; longer treatments induced TEX re-organization into smaller membrane-bound vesicles. The TEX lumen contained long fragments of protected genomic DNA with a mutational signature reflecting that of the tumor. Conclusions: Nucleic acids present on the TEX surface support the vesicular integrity. The TEX lumen contains membrane-protected large (ds)DNA fragments with the mutational signature of the parent tumor. The presence of surface and luminal nucleic acids in TEX, and especially their mutational signature, suggests that TEX may serve as highly promising cancer-specific biomarkers. Full article

Epstein–Barr virus (EBV) is a human pathogenic and oncogenic herpesvirus, with worldwide importance, at times associated with serious to life-threatening symptoms, especially in immunocompromised hosts. The available preventive options against EBV disease are limited to medically elaborate and cost-intensive measures of cell-based immunotherapy. The development of novel options of anti-EBV drug targeting is currently a matter of intense international efforts. A putative target of the antiviral therapy approach is the EBV-encoded protein kinase BGLF4, which fulfills a multifaceted role in productive viral replication. So far, viral BGLF4 interactor proteins and phosphorylated substrates have occasionally been reported, but in particular cellular interactors await further characterization concerning both, their relevance for BGLF4 functionality and their accessibility to antiviral drugs. In this study, we have analyzed host cell–BGLF4 interaction, BGLF4 kinase properties, and BGLF4-directed small molecules. The main results are as follows: (i) a mass spectrometry-based interactomic study was performed with EBV-producing Akata-BX1 cells, thereby identifying the human pyruvate dehydrogenase (PDH) as a relevant BGLF4 interactor; (ii) BGLF4–PDH interaction was confirmed by protein coimmunoprecipitation, subcellular cofractionation, and confocal imaging; (iii) the BGLF4-mediated phosphorylation of PDH was demonstrated by an in vitro kinase assay (IVKA); (iv) a reduction in PDH phosphorylation was shown for selected kinase inhibitors, which also exerted BGLF4-directed inhibitory potential in a quantitative qSox-IVKA, and (v) these hit compounds showed anti-EBV activity in lytically induced P3HR-1 cells using qPCR measurement, as well as PDH-inhibitory activity using standardized PDH assays. These data lead to an improved understanding of EBV–host interaction that may open novel anti-EBV preventive opportunities. Combined, the findings point to PDH as a new cellular interactor of the EBV kinase BGLF4. Also, notably, the data on pharmacological intervention with kinase activity or substrate phosphorylation may possibly provide as yet untapped options of antiviral drug targeting. Full article

Human immunodeficiency virus type 1 (HIV-1) is a retrovirus that integrates into the host cell’s DNA as a provirus. Transcription from the provirus is regulated in large part by cellular proteins and epigenetic factors. These may be repressive or permissive to productive infection. The host factors that regulate this balance are therefore attractive targets for HIV-1 therapeutics. Indeed, proviral chromatin is the focus of two of the current HIV-1 cure strategies. “Shock and Kill” uses latency reversal agents to open the provirus’s chromatin, promoting high levels of gene expression that induce the killing of infected cells. “Block and Lock” uses latency promoting agents to induce heterochromatin, blocking transcription and forcing HIV-1 into a state of deep latency. Here, the compounds investigated in both strategies are reviewed, including their chemical structures, mechanisms of action, and clinical results. Finally, the use of CRISPR-Cas therapeutics and the impact of chromatin architecture on its efficacy are discussed. Full article

Lipoprotein(a) [Lp(a)] is a low-density lipoprotein-like particle that contains a unique apolipoprotein(a) [apo(a)] component covalently bound to apolipoprotein B-100. Elevated levels of Lp(a) have been identified as a well-established and genetically determined risk factor for atherosclerotic cardiovascular disease, including coronary artery disease, stroke, and calcific aortic valve stenosis. In contrast to other lipids, Lp(a) concentrations are minimally influenced by lifestyle or traditional lipid-lowering therapies, emphasizing the necessity for novel treatment approaches. This narrative review summarizes current and emerging therapeutic strategies for reducing Lp(a) levels. Such strategies include traditional agents such as niacin and PCSK9 inhibitors, as well as innovative therapies such as antisense oligonucleotides, RNA interference-based molecules, and small-molecule inhibitors. The mechanisms of action of these agents, in addition to clinical trial data and their capacity to modify cardiovascular outcomes, are explored in further detail. Furthermore, the current status of clinical guidelines and the evolving role of Lp(a)-targeted therapies in cardiovascular risk stratification are reviewed. A particular emphasis is placed on therapies that are in the advanced stages of clinical development. These include late-phase outcome trials and orally administered agents, which have the potential to significantly impact future clinical practice. The integration of mechanistic data with ongoing and completed clinical studies has been undertaken in order to provide a comprehensive framework for understanding the therapeutic potential of Lp(a) in the context of cardiovascular prevention. Full article