Search Results (122)

Background: Among the 15 human (h) carbonic anhydrase (CA; EC 4.2.1.1) isoforms, hCA IX and XII are particularly important due to their roles in tumor cell growth and survival, identifying them as promising targets for anticancer therapy. As a result, considerable effort has been directed toward the development of novel inhibitors that are highly selective for these isoforms. Methods: A library of twelve novel N-aryl-2-(4-sulfamoylphenyl)hydrazine-1-carbothioamides 3 along with two new N-aryl-2-(4-sulfamoylphenyl)hydrazine-1-carboxamide derivatives 5 were synthesized and their inhibition abilities were tested against four human carbonic anhydrase isozymes (hCA I, II, IX and XII) related to some global diseases including glaucoma, cancer and osteoporosis. Results: All compounds exhibited potent inhibition of the tested isoforms in the nanomolar range. Compound 3i showed the highest inhibition of hCA I activity but demonstrated poor selectivity toward the other isoforms. Compound 3h displayed superior selectivity for hCA II over hCA I (hCA I/II = 37) and exhibited 2.5-fold higher inhibitory activity compared to acetazolamide (AAZ). Among the tested compounds, 3l (K_i = 32.1 nM) demonstrated markedly improved selectivity for hCA IX over hCA I, II, and XII relative to the standard drug. Notably, compound 3a showed the most potent inhibition against hCA XII (K_i = 6.8 nM), comparable to AAZ, while exhibiting significantly greater selectivity over off-target isoforms and the other tumor-associated isozyme (hCA IX/XII = 20 versus hCA IX/XII = 4.5 for AAZ). Conclusions: The present study suggests potent lead compounds as selective hCA IX and XII inhibitors with anticancer activity. Full article

Background/Objectives: Cholangiocarcinoma (CCA) is an aggressive malignancy with a poor prognosis, creating an urgent need for novel biomarkers to improve risk stratification. The prognostic significance of the transmembrane glycoprotein CD44 and its isoforms (CD44s, v5, v6) in CCA remains controversial. This preliminary study aimed to investigate whether the combined loss of these isoforms could serve as a distinct prognostic indicator. Methods: We evaluated the expression of CD44s, CD44v5, and CD44v6 via immunohistochemistry on a retrospective cohort of 61 paraffin-embedded CCA patient tissue blocks from Ramathibodi Hospital, Bangkok, Thailand. Expression levels were correlated with clinicopathological parameters. Survival analyses, including Kaplan–Meier and Cox proportional hazards models, were used to determine the prognostic value of individual isoforms and the complete absence of all three. Results: Expression of CD44s, CD44v5, and CD44v6 was found in 52.5%, 47.5%, and 82.0% of tumors, respectively. In univariate and multivariate analyses, the expression of any single isoform was not a significant predictor of overall survival. However, a subgroup of 8 patients (13.1%) was identified whose tumors were negative for all three isoforms, a phenotype we termed “CD44s-v5-v6 Null”. This status was significantly associated with advanced TNM stages (p = 0.022). Patients with these Null tumors also showed a clinically relevant, though not statistically significant, trend towards poorer survival (median 7.0 vs. 12.0 months, p = 0.336). Conclusions: Individual CD44 isoforms did not serve as reliable independent prognostic markers in this cohort. Instead, the complete loss of the CD44 expression program characterizes a potential “CD44s-v5-v6 Null” phenotype associated with advanced-stage disease. Full article

Chitin is an essential polysaccharide of the fungal cell wall, critical for structural integrity, cell division and, in pathogenic fungi, virulence. As chitin is absent in both plant and mammalian systems, chitin synthases are considered attractive targets for the specific control of fungal pathogens. Yet despite decades of research, structural information on chitin synthases was lacking and inhibitors have failed to gain approval in the clinic. Current inhibitors are also ineffective against major agricultural pathogens such as Aspergillus and Fusarium species, largely due to the presence of multiple chitin synthase isoforms in filamentous fungi and the cell wall compensatory response induced under stress. However, recent cryo-electron microscopy structures of Class I chitin synthases from yeasts Saccharomyces cerevisiae and Candida albicans and an oomycete chitin synthase have provided unprecedented insights into the structural and mechanistic properties of these large, transmembrane proteins. These studies revealed conserved, domain-swapped homodimer architectures, distinct substrate binding and catalytic pockets, and sophisticated intrinsic regulatory mechanisms. With these breakthroughs, this review summarises our current understanding of fungal chitin biosynthesis, the challenges that remain to fully biochemically characterise these enzymes, and considers how the new structural insights may guide the development of broad-spectrum antifungals. Full article

Isoforms of prostate transmembrane protein, androgen induced 1 (PMEPA1), are regulated either by TGF-beta or AR activation and provide negative loop-regulation of these signaling pathways. High levels of PMEPA1 protein have been observed in various tumor types, including prostate, bladder, colorectal cancers, and glioblastoma. Direct oncogenic role of PMEPA1 in hepatocellular carcinoma has been recently shown on an animal model. New studies also indicate an upregulation of PMEPA1 in tumor-associated immune and stromal cells; however, its specific role in tumor stromal cells remains largely unexplored. In our previous research, we developed a cancer-stroma sphere (CSS) model that integrates tumor cells with mesenchymal stem cells (MSCs). Evaluations of chemotherapy and CAR-T therapies on CSSs have demonstrated that this model closely mimics in vivo data regarding cytotoxicity and adverse effects of therapy. In the present study, we reveal that PMEPA1 is significantly overexpressed in MSCs within the CSS. Moreover, this overexpression has been induced under short-term co-culture conditions. Among the five isoforms of PMEPA1, PMEPA1a and PMEPA1b isoforms have been detected in MSCs. These findings underscore the potential role of PMEPA1 in the tumor microenvironment modulation by MSCs. Full article

The family of voltage-dependent anion channels (VDACs) comprises three isoforms (VDAC-1, VDAC-2, VDAC-3). VDACs have been extensively described as localised in the outer mitochondrial membrane where they are involved in the exchange of ions, metabolites, and ATP/ADP between mitochondria and cytosol. The VDAC interacts with disease-specific proteins and thus regulates the mitochondrial function and controls the cellular energy resources, explaining its involvement in cell death and apoptosis. In addition, VDAC-1 and -2 can also be found at other cellular locations such as in the sarcoplasmic reticulum, in the endoplasmic reticulum, as well as in the plasma membrane. Through single-channel pore regulation, oligomerisation, or changed expression levels the VDAC is involved in different neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, Amyotrophic lateral sclerosis, Huntington’s disease, and others. Here, we critically summarise current discussions about the VDAC as a common key player for these diseases. We suggest that the VDAC acts as a transmembrane multifunctional regulatory protein which might serve as a pharmacological target for the development of novel drugs against neurodegenerative diseases such as the application of recombinant antibody technology. Full article

1-Acylglycerol-3-phosphate O-acyltransferase (1-AGPAT) is an enzyme family composed of 11 isoforms. Notably, 1-AGPAT 2, the most studied isoform since its discovery, is a critical enzyme in the triglyceride synthesis pathway, converting lysophosphatidic acid to phosphatidic acid. In addition, AGPAT2 gene expression is shown to be essential for adipocyte development and maturation. Defects in AGPAT2 are responsible for significant pathophysiological alterations related to adipose tissue (AT). Pathogenic variants in this gene are the molecular etiology of Congenital Generalized Lipodystrophy type 1 (CGL1), in which fatty tissue is absent from birth. Metabolically, these individuals have several metabolic complications, including hypoleptinemia, hypoadiponectinemia, hyperglycemia, and hypertriglyceridemia. Furthermore, numerous AGPAT2 pathogenic variants that enormously affect the amino acid sequence, the tertiary structure of 1-AGPAT 2, and their transmembrane and functional domains were found in CGL1 patients. However, studies investigating the genotype–phenotype relationship in this disease are scarce. Here, we used bioinformatics tools to verify the effect of the main pathogenic variants reported in the AGPAT2 gene: c.366-588del, c.589-2A>G, c.646A>T, c.570C>A, c.369-372delGCTC, c.202C>T, c.514G>A, and c.144C>A in the 1-AGPAT 2 membrane topology. We also correlated the phenotype of CGL1 subjects harboring these variants to understand the genotype–phenotype relationship. We provided an integrative view of clinical, genetic, and metabolic features from CGL1 individuals, helping to understand the role of 1-AGPAT 2 in the pathogenesis of this rare disease. Data reviewed here highlight the importance of new molecular studies to improve our knowledge concerning clinical and genetic heterogeneity in CGL1. Full article

Thyroid cancer (TC) is a significant global health issue that exhibits notable heterogeneity in incidence and outcomes. In low-resource settings such as Africa, delayed diagnosis and limited healthcare access exacerbate mortality rates. Among follicular cell-derived thyroid cancers—including papillary (PTC), follicular (FTC), anaplastic (ATC), and poorly differentiated (PDTC) subtypes—the role of CD44 variants has emerged as a critical factor influencing tumor progression and multidrug resistance (MDR). CD44, a transmembrane glycoprotein, and its splice variants (CD44v) mediate cell adhesion, migration, and survival, contributing to cancer stem cell (CSC) maintenance and therapy resistance. Differential expression patterns of CD44 isoforms across TC subtypes have shown diagnostic, prognostic, and therapeutic implications. Specifically, CD44v6 expression in PTC has been correlated with metastasis and aggressive tumor behavior, while in FTC, its expression aids in distinguishing malignant from benign lesions. Furthermore, CD44 contributes to MDR through enhanced drug efflux via ABC transporters, apoptosis evasion, and CSC maintenance via the Wnt/β-catenin and PI3K/Akt pathways. Targeted therapies against CD44 such as monoclonal antibodies, hyaluronic acid-based nanocarriers, and gene-editing technologies hold promise in overcoming MDR. However, despite the mounting evidence supporting CD44-targeted strategies in various cancers, research on this therapeutic potential in TC remains limited. This review synthesizes existing knowledge on CD44 variant expression in follicular cell-derived thyroid cancers and highlights potential therapeutic strategies to mitigate MDR, particularly in high-burden regions, thereby improving patient outcomes and survival. Full article

In the search for new selective inhibitors of human carbonic anhydrase (hCA), particularly the cancer-associated isoforms hCA IX and hCA XII, a series of 4-substituted pyridine-3-sulfonamides was synthesized using the “click” CuAAC reaction, proven by X-ray crystallography, and evaluated for their inhibitory activity against hCA I, hCA II, hCA IX, and hCA XII. Additional molecular docking studies and cytostatic activity assays on three cancer cell lines were conducted. The compounds exhibited a broad range of inhibitory activity, with K_I reaching 271 nM for hCA II, 137 nM for hCA IX, and 91 nM for hCA XII. Notably, compound 4 demonstrated up to 5.9-fold selectivity toward the cancer-associated hCA IX over the ubiquitous hCA II, while compound 6 exhibited a remarkable 23.3-fold selectivity between transmembrane isoforms hCA IX and hCA XII. Molecular docking studies have shown the possibility of selective interaction with the hydrophilic or lipophilic half of the active site, what results from the adjacent (3,4) position of the “tail” in relation to the sulfonamide group. Full article

The transfer time of Atlantic salmon smolts from freshwater to seawater remains a challenge in aquaculture, with the “smolt window” referring to the optimal timeframe for seawater readiness. Our study monitored Atlantic salmon osmoregulatory adaptations during smoltification under continuous light (LL) and winter signal regime (6 weeks LD 12:12) followed by 6 or 8 weeks of constant light. Fish were subsequently reared in seawater for 8 weeks and subjected to a stress event of cyclic hypoxia at the conclusion of the trial. Significant differences in growth trajectories were observed between the LL and LD groups, with fish receiving the winter signal showing compensatory growth after seawater transfer. Gill Na⁺/K⁺-ATPase (NKA) activity, plasma ions, glucose, and cortisol levels confirmed the importance of the winter signal for seawater adaptation. Molecular markers, including nka isoforms, Na⁺-K⁺-2Cl⁻ cotransporter (nkcc), cystic fibrosis transmembrane conductance regulator (cftr), and Na⁺/HCO₃⁻ cotransporter (nbc), showed distinct temporal expression patterns, particularly in gills and midgut. Notably, the LD group with delayed seawater transfer exhibited enhanced growth and improved hypo-osmoregulatory capacity. These findings underscore the advantages of a winter signal in smoltification and suggest that delaying seawater transfer for up to 8 weeks could be beneficial. Full article

The Connexin43 transmembrane protein (Cx43), encoded by the GJA1 gene, is a member of a multigenic family of proteins that oligomerize to form hemichannels and intercellular channels, allowing gap junctional intercellular communication between adjacent cells or communication between the intracellular and extracellular compartments. Cx43 has long been shown to play a significant but complex role in cancer development, acting as a tumor suppressor and/or tumor promoter. The effects of Cx43 are associated with both channel-dependent and -independent functionalities and differ depending on the expression level, subcellular location and the considered stage of cancer progression. Recently, six isoforms of Cx43 have been described and one of them, called GJA1-20k, has also been found to be expressed in cancer cells. This isoform is generated by alternative translation and corresponds to the end part of the fourth transmembrane domain and the entire carboxyl-terminal (CT) domain. Initial studies in the cardiac model implicated GJA1-20k in the trafficking of full-length Cx43 to the plasma membrane, in cytoskeletal dynamics and in mitochondrial fission and subcellular distribution. As these processes are associated with cancer progression, a potential link between Cx43 functions, mitochondrial activity and GJA1-20k expression can be postulated in this context. This review synthetizes the current knowledge on GJA1-20k and its potential involvement in processes related to epithelial-to-mesenchymal transition (EMT) and the proliferation, dissemination and quiescence of cancer cells. Particular emphasis is placed on the putative roles of GJA1-20k in full-length Cx43 exportation to the plasma membrane, mitochondrial activity and functions originally attributed to the CT domain. Full article

Na⁺-K⁺ ATPase is an integral component of cardiac sarcolemma and consists of three major subunits, namely the α-subunit with three isoforms (α₁, α₂, and α₃), β-subunit with two isoforms (β₁ and β₂) and γ-subunit (phospholemman). This enzyme has been demonstrated to transport three Na and two K ions to generate a trans-membrane gradient, maintain cation homeostasis in cardiomyocytes and participate in regulating contractile force development. Na⁺-K⁺ ATPase serves as a receptor for both exogenous and endogenous cardiotonic glycosides and steroids, and a signal transducer for modifying myocardial metabolism as well as cellular survival and death. In addition, Na⁺-K⁺ ATPase is regulated by different hormones through the phosphorylation/dephosphorylation of phospholemman, which is tightly bound to this enzyme. The activity of Na⁺-K⁺ ATPase has been reported to be increased, unaltered and depressed in failing hearts depending upon the type and stage of heart failure as well as the association/disassociation of phospholemman and binding with endogenous cardiotonic steroids, namely endogenous ouabain and marinobufagenin. Increased Na⁺-K⁺ ATPase activity in association with a depressed level of intracellular Na⁺ in failing hearts is considered to decrease intracellular Ca²⁺ and serve as an adaptive mechanism for maintaining cardiac function. The slight to moderate depression of Na⁺-K⁺ ATPase by cardiac glycosides in association with an increased level of Na⁺ in cardiomyocytes is known to produce beneficial effects in failing hearts. On the other hand, markedly reduced Na⁺-K⁺ ATPase activity associated with an increased level of intracellular Na⁺ in failing hearts has been demonstrated to result in an intracellular Ca²⁺ overload, the occurrence of cardiac arrhythmias and depression in cardiac function during the development of heart failure. Furthermore, the status of Na⁺-K⁺ ATPase activity in heart failure is determined by changes in isoform subunits of the enzyme, the development of oxidative stress, intracellular Ca²⁺-overload, protease activation, the activity of inflammatory cytokines and sarcolemmal lipid composition. Evidence has been presented to show that marked alterations in myocardial cations cannot be explained exclusively on the basis of sarcolemma alterations, as other Ca²⁺ channels, cation transporters and exchangers may be involved in this event. A marked reduction in Na⁺-K⁺ ATPase activity due to a shift in its isoform subunits in association with intracellular Ca²⁺-overload, cardiac energy depletion, increased membrane permeability, Ca²⁺-handling abnormalities and damage to myocardial ultrastructure appear to be involved in the progression of heart failure. Full article

Large-scale genetic studies have identified numerous genetic risk factors that suggest a central role for innate immune cells in susceptibility to Alzheimer’s disease (AD). CD33, an immunomodulatory transmembrane sialic acid binding protein expressed on myeloid cells, was identified as one such genetic risk factor associated with Alzheimer’s disease. Several studies explored the molecular outcomes of genetic variation at the CD33 locus. It has been determined that the risk variant associated with AD increases the expression of the large isoform of CD33 (CD33M) in innate immune cells and alters its biological functions. CD33 is thought to signal via the interaction of its ITIM motif and the protein tyrosine phosphatase, SHP-1. Here, we utilize different molecular and computational approaches to investigate how AD-associated genetic variation in CD33 affects its interaction with SHP-1 in human microglia and microglia-like cells. Our findings demonstrate a genotype-dependent interaction between CD33 and SHP-1, which may functionally contribute to the AD risk associated with this CD33 variant. We also found that CD33-PTPN6 (SHP-1) gene–gene interactions impact AD-related traits, while CD33-PTPN11 (SHP-2) interactions do not. Full article

Aquaporins (AQPs) are transmembrane channels initially discovered for their role in water flux facilitation through biological membranes. Over the years, a much more complex and subtle picture of these channels appeared, highlighting many other solutes accommodated by AQPs and a dense regulatory network finely tuning cell membranes’ water permeability. At the intersection between several transduction pathways (e.g., cell volume regulation, calcium signaling, potassium cycling, etc.), this wide and ancient protein family is considered an important therapeutic target for cancer treatment and many other pathophysiologies. However, a precise and isoform-specific modulation of these channels function is still challenging. Among the modulators of AQPs functions, cations have been shown to play a significant contribution, starting with mercury being historically associated with the inhibition of AQPs since their discovery. While the comprehension of AQPs modulation by cations has improved, a unifying molecular mechanism integrating all current knowledge is still lacking. In an effort to extract general trends, we reviewed all known modulations of AQPs by cations to capture a first glimpse of this regulatory network. We paid particular attention to the associated molecular mechanisms and pinpointed the residues involved in cation binding and in conformational changes tied up to the modulation of the channel function. Full article

Difamilast, a phosphodiesterase 4 (PDE4) inhibitor, has been shown to be effective in the treatment of atopic dermatitis (AD), although the mechanism involved remains unclear. Since IL-33 plays an important role in the pathogenesis of AD, we investigated the effect of difamilast on IL-33 activity. Since an in vitro model of cultured normal human epidermal keratinocytes (NHEKs) has been utilized to evaluate the pharmacological potential of adjunctive treatment of AD, we treated NHEKs with difamilast and analyzed the expression of the suppression of tumorigenicity 2 protein (ST2), an IL-33 receptor with transmembrane (ST2L) and soluble (sST2) isoforms. Difamilast treatment increased mRNA and protein levels of sST2, a decoy receptor suppressing IL-33 signal transduction, without affecting ST2L expression. Furthermore, supernatants from difamilast-treated NHEKs inhibited IL-33-induced upregulation of TNF-α, IL-5, and IL-13 in KU812 cells, a basophil cell line sensitive to IL-33. We also found that difamilast activated the aryl hydrocarbon receptor (AHR)–nuclear factor erythroid 2-related factor 2 (NRF2) axis. Additionally, the knockdown of AHR or NRF2 abolished the difamilast-induced sST2 production. These results indicate that difamilast treatment produces sST2 via the AHR–NRF2 axis, contributing to improving AD symptoms by inhibiting IL-33 activity. Full article

Antithrombin III (ATIII) is a potent endogenous anticoagulant that binds to heparan sulfate proteoglycans (HSPGs) on endothelial cells’ surfaces. Among these HSPGs, syndecans (SDCs) are crucial as transmembrane receptors bridging extracellular ligands with intracellular signaling pathways. Specifically, syndecan-4 (SDC4) has been identified as a key receptor on endothelial cells for transmitting the signaling effects of ATIII. Meanwhile, SDCs have been implicated in facilitating the cellular internalization of SARS-CoV-2. Given the complex interactions between ATIII and SDC4, our study analyzed the impact of ATIII on the virus entry into host cells. While ATIII binds to all SDC isoforms, it shows the strongest affinity for SDC4. SDCs’ heparan sulfate chains primarily influence ATIII’s SDC attachment, although other parts might also play a role in ATIII’s dominant affinity toward SDC4. ATIII significantly reduces SARS-CoV-2′s cellular entry into cell lines expressing SDCs, suggesting a competitive inhibition mechanism at the SDC binding sites, particularly SDC4. Conversely, the virus or its spike protein decreases the availability of SDCs on the cell surface, reducing ATIII’s cellular attachment and hence contributing to a procoagulant environment characteristic of COVID-19. Full article