Search Results (541)

Nosocomial infections caused by ESKAPE pathogens represent a significant burden to global health. These pathogens may exhibit multidrug resistance (MDR) mechanisms, of which mechanisms such as efflux pumps and biofilm formation are gaining significant importance. Multidrug resistance mechanisms in ESKAPE pathogens have led to an increase in the effective costs in health care and a higher risk of mortality in hospitalized patients. These pathogens utilize antimicrobial efflux pump mechanisms and bacterial biofilm-forming capabilities to escape the bactericidal action of antimicrobials. ESKAPE bacteria forming colonies demonstrate increased expression of efflux pump-encoding genes. Efflux pumps not only expel antimicrobial agents but also contribute to biofilm formation by bacteria through (1) transport of molecules and transcription factors involved in biofilm quorum sensing, (2) bacterial fimbriae structure transport for biofilm adhesion to surfaces, and (3) regulation of a transmembrane gradient to survive the difficult conditions of biofilm microenvironments. The synergistic role of these mechanisms complicates treatment outcomes. Given the mechanistic link between biofilms and efflux pumps, therapeutic strategies should focus on targeting anti-biofilm mechanisms alongside efflux pump inactivation with efflux pump inhibitors. This review explores the molecular interplay between efflux pumps and biofilm formation, emphasizing potential therapeutic strategies such as efflux pump inhibitors (EPIs) and biofilm-targeting agents. Full article

Prostate cancer continues to be the most common cause of cancer-related disease and mortality among men worldwide, especially in the advanced stages, notably metastatic castration-resistant prostate cancer (mCRPC), which poses significant treatment challenges. Docetaxel, a widely used chemotherapeutic agent, has long served as the standard treatment, offering survival benefits and mitigation. However, its clinical impact is frequently undermined by the development of chemoresistance, which is a formidable challenge that leads to treatment failure and disease progression. The mechanisms driving docetaxel resistance are diverse and complex, encompassing modifications in androgen receptor signaling, drug efflux transporters, epithelial-mesenchymal transition (EMT), microtubule alterations, apoptotic pathway deregulation, and tumor microenvironmental influences. Recent evidence suggests that extracellular RNAs influence drug responses, further complicating the resistance landscape. This review offers a broad discussion on the mechanisms of resistance and explores novel therapeutic approaches to address them. These include next-generation taxanes, targeted molecular inhibitors, immunotherapies, and combination regimens that can be designed to counteract specific resistance pathways. By broadening our understanding of docetaxel resistance, this review highlights potential strategies to improve therapeutic efficacy and the potential to enhance outcomes in patients with advanced treatment-resistant prostate cancer. Full article

Efflux is one of the key mechanisms used by Gram-negative bacteria to reduce internal antibiotic concentrations. These active transport systems recognize and expel a wide range of toxic molecules, including antibiotics, thereby contributing to reduced antibiotic susceptibility and allowing the bacteria to acquire additional resistance mechanisms. To date, unlike other resistance mechanisms such as enzymatic modification or target mutations/masking, efflux is challenging to detect and counteract in clinical settings, and no standardized methods are currently available to diagnose or inhibit this mechanism effectively. This review first outlines the structural and functional features of major efflux pumps in Gram-negative bacteria and their role in antibiotic resistance. It then explores various strategies used to curb their activity, with a particular focus on efflux pump inhibitors under development, detailing their structural classes, modes of action, and pharmacological potential. We discuss the main obstacles to their development, including the structural complexity and substrate promiscuity of efflux mechanisms, the limitations of current screening methods, pharmacokinetic and tissue distribution issues, and the risk of off-target toxicity. Overcoming these multifactorial barriers is essential to the rational development of less efflux-prone antibiotics or of efflux pump inhibitors. Full article

Nonspecific toxicity to normal and malignant cells restricts the clinical utility of many anticancer drugs. In particular, anemia in cancer patients develops due to drug-induced toxicity to red blood cells (RBCs). The anticancer alkaloid, cepharanthine (CEP), elicits distinct forms of cell death including apoptosis and autophagy, but its cytotoxicity to RBCs has not been investigated. Colorimetric and fluorometric techniques were used to assess eryptosis and hemolysis in control and CEP-treated RBCs. Cells were labeled with Fluo4/AM and annexin-V-FITC to measure Ca²⁺ and phosphatidylserine (PS) exposure, respectively. Forward scatter (FSC) was detected to estimate cell size, and extracellular hemoglobin along with lactate dehydrogenase and aspartate transaminase activities were assayed to quantify hemolysis. Physiological manipulation of the extracellular milieu and various signaling inhibitors were tested to dissect the underlying mechanisms of CEP-induced RBC death. CEP increased PS exposure and hemolysis indices and decreased FSC in a concentration-dependent manner with prominent membrane blebbing. Although no Ca²⁺ elevation was detected, chelation of intracellular Ca²⁺ by BAPTA-AM reduced hemolysis. Whereas SB203580, D4476, acetylsalicylic acid, necrosulfonamide, and melatonin inhibited both PS exposure and hemolysis, staurosporin, L-NAME, ascorbate, caffeine, adenine, and guanosine only prevented hemolysis. Interestingly, sucrose had a unique dual effect by exacerbating PS exposure and reversing hemolysis. Of note, blocking KCl efflux augmented PS exposure while aggravating hemolysis only under Ca²⁺-depleted conditions. CEP activates Ca²⁺-independent pathways to promote eryptosis and hemolysis. The complex cytotoxic profile of CEP can be mitigated by targeting the identified modulatory pathways to potentiate its anticancer efficacy. Full article

Background and aim: ANGPTL3 is a hepatokine acting as a negative regulator of lipoprotein lipase (LPL) through its N-terminal domain. Besides this activity, the C-terminal domain of ANGPTL3 interacts with integrin αVβ3. Since integrins are involved in inflammation and in the initiation of atherosclerotic plaque, the aim of our study was to evaluate the potential direct pro-inflammatory action of ANGPTL3 through the interaction of the fibrinogen-like domain and integrin αVβ3. Methods: We utilized cultured THP-1 human-derived macrophages and evaluated their pro-inflammatory phenotype in response to treatment with human recombinant ANGPTL3 (hANGPTL3). By Western blot, RT-qPCR, biochemical analysis, and ELISA assays, we determined the expression of genes and proteins involved in lipid metabolism and inflammatory response as well as intracellular cholesterol and triglyceride levels. In addition, we evaluated the effect of hANGPTL3 on the cellular cholesterol efflux process. Results: Incubation of THP-1-derived macrophages with 100 ng/mL of hANGPTL3 increased the mRNA expression of the pro-inflammatory cytokines IL-1β, IL-6, and TNFα (respectively, 1.87 ± 0.08-fold, 1.35 ± 0.11-fold, and 2.49 ± 0.43-fold vs. control). The secretion of TNFα, determined by an ELISA assay, was also induced by hANGPTL3 (1.98 ± 0.4-fold vs. control). The pro-inflammatory effect of hANGPTL3 was partially counteracted by co-treatment with the integrin αVβ3 inhibitor RGD peptide, reducing the mRNA levels of IL-1β (3.35 ± 0.35-fold vs. 2.54 ± 0.25-fold for hANGPTL3 vs. hANGPTL3 + RGD, respectively). Moreover, hANGPTL3 reduced cholesterol efflux to apoA-I, with a parallel increase in the intracellular triglyceride and cholesterol contents by 31.2 ± 2.8% and 20.0 ± 4.1%, respectively, compared to the control. Conclusions: ANGPTL3 is an important liver-derived regulator of plasma lipoprotein metabolism, and overall, our results add a new important pro-inflammatory activity of this circulating protein. This new function of ANGPTL3 could also be related to triglyceride and cholesterol accumulation into macrophages. Full article

Growth hormone (GH) signaling has been implicated in tumor progression and therapy resistance across multiple cancer types, yet its role in bladder cancer remains largely unexplored. In this study, we investigated the impact of GH and its receptor (GHR) on therapy resistance and disease progression in urothelial carcinoma (UC) through integrated transcriptomic and in vitro analyses. Transcriptomic profiling of The Cancer Genome Atlas bladder cancer cohort revealed that high tumoral GHR expression was associated with differential upregulation of genes involved in drug efflux, epithelial-to-mesenchymal transition (EMT), and extracellular matrix (ECM) remodeling. Notably, elevated GHR levels correlated with significantly reduced overall survival in patients with UC. In parallel, in vitro experiments demonstrated that GH promotes chemoresistance in UC cell lines via upregulation of ATP-binding cassette-containing (ABC) transporters and activation of EMT. GH also modulated ECM-remodeling-associated genes in a chemotherapy-dependent manner, including matrix metalloproteinases and tissue inhibitors of metalloproteinases. Importantly, these effects were abrogated by Pegvisomant, a GHR antagonist, indicating the functional relevance of GH/GHR signaling in the mediation of these phenotypes. Collectively, our findings support a mechanistic role for GH signaling in driving therapy resistance and tumor aggressiveness in bladder cancer and suggest GHR antagonism as a potential therapeutic strategy to improve treatment outcomes. Full article

The blood–brain barrier (BBB) is a highly selective interface between the bloodstream and the brain that prevents systemically administered therapeutics from effectively reaching tumor cells. As tumors progress, this barrier undergoes structural and functional alterations, giving rise to the blood–tumor barrier (BTB)—a pathologically modified structure that, despite increased permeability, often exhibits heterogeneous and clinically insufficient drug transport. Although a new generation of therapies is promising, their therapeutic potential cannot be realized unless the challenges posed by these barriers are effectively addressed. Various pharmacological strategies were explored to enhance brain tumor drug delivery. These include receptor-mediated disruption, inhibition of efflux transporters, and the engineering of delivery platforms that leverage endogenous transport pathways—such as carrier-mediated, adsorptive-mediated, and receptor-mediated mechanisms—as well as cell-mediated drug delivery. This review synthesizes (1) the BBB and BTB’s structural characteristics; (2) the influence of the tumor microenvironment (TME) on drug delivery; (3) pharmacological strategies to enhance drug accumulation within brain tumors; (4) the integration of pharmacological methods with neurosurgical techniques to enhance drug delivery. As efforts to improve drug delivery across the BBB and BTB accelerate, this review aims to map the current landscape of pharmacological approaches for enhancing drug penetration into brain tumors. Full article

Familial hypercholesterolemia (FH) is a genetic disorder marked by significantly elevated levels of low-density lipoprotein cholesterol (LDL-C) since childhood, substantially increasing the risk of premature atherosclerosis and cardiovascular disease. While dysfunction of hepatic LDL-C receptors is the main underlying cause, the gastrointestinal tract plays a key role in cholesterol homeostasis and represents an important therapeutic target. Inhibition of intestinal cholesterol absorption has emerged as an effective strategy in the management of pediatric FH, particularly in patients for whom statins may not be the ideal first-line treatment. Ezetimibe, an inhibitor of the Niemann-Pick C1-like 1 (NPC1L1) protein, has been shown to reduce LDL-C levels in children with FH, with a greater efficacy observed when used in combination with statins. Bile acid sequestrants also enhance cholesterol excretion but are often limited by gastrointestinal side effects, while dietary interventions, such as phytosterol supplementation and fiber-enriched diets, provide additional benefits in lowering LDL-C and are generally well tolerated. Emerging therapies, including microbiota-targeted strategies and novel cholesterol absorption inhibitors, show promise for expanding future treatment options. This review explores the mechanisms of intestinal cholesterol absorption and their relevance to pediatric FH. We examine key pathways, including dietary cholesterol uptake through NPC1L1, bile acid reabsorption, and cholesterol efflux mediated by ATP-binding cassette transporters, while also discussing clinical and experimental evidence on pharmacological and dietary interventions that modulate these pathways. A deeper understanding of cholesterol metabolism, the emerging role of the gut microbiota, and innovative therapeutic agents can support the development of more effective and personalized approaches to the treatment of children with FH. Full article

The global rise of carbapenem-resistant Acinetobacter baumannii (CRAB) strains poses a critical challenge to healthcare systems due to limited therapeutic options and high mortality rates, especially in intensive care settings. This review explores the epidemiological landscape and molecular mechanisms driving carbapenem resistance, including the production of diverse beta-lactamases (particularly OXA-type enzymes), porin loss, efflux pump overexpression, and mutations in antibiotic targets. Emerging treatment strategies are discussed, such as the use of new beta-lactam–beta-lactamase inhibitor combinations (e.g., sulbactam–durlobactam), siderophore cephalosporins, next-generation polymyxins, as well as novel agents like zosurabalpin and rifabutin (BV100). Alternative approaches—including phage therapy, antimicrobial peptides, CRISPR-based gene editing, and nanoparticle-based delivery systems—are also evaluated for their potential to bypass traditional resistance mechanisms. Furthermore, advances in artificial intelligence and multi-omics integration are highlighted as tools for identifying novel drug targets and predicting resistance profiles. Together, these innovations represent a multifaceted strategy to overcome CRAB infections, yet their successful implementation requires further clinical validation and coordinated surveillance efforts. This analysis highlights the urgent need for continued investment in innovative treatments and effective resistance monitoring to limit the spread of CRAB and protect the effectiveness of last-line antibiotics. Full article

Ruxolitinib, a clinically approved JAK1/2 inhibitor used in the treatment of hematologic malignancies and inflammatory conditions, has been shown to interfere with the function of cytotoxic T lymphocytes (CTLs). Previous studies supported the involvement of the multidrug resistance transporter P-glycoprotein (Pgp/ABCB1) in CTL biology; however, the nature of its regulation remains unclear. To address this, we investigated the impact of ruxolitinib on Pgp expression and function in human CD8⁺ T cells. We demonstrate that CD8⁺ T lymphocytes express Pgp dynamically at both the mRNA and protein levels across naïve, short-term, and long-term activation states. Ruxolitinib increased the calcein accumulation in human Pgp-overexpressing NIH-3T3 cells and in CTLs and directly modulated Pgp function by increasing its basal ATPase activity in a concentration-dependent manner (10–100 μM), similar to the effect of the known Pgp substrate/modulator verapamil. Although measurable ATPase stimulation and transport inhibition were observed at supratherapeutic concentrations of ruxolitinib, its Pgp-mediated efflux may also occur at therapeutically relevant concentrations. In contrast, at therapeutically relevant plasma concentrations (1–3 μM), ruxolitinib significantly stabilized the mRNA expression of Pgp during early T-cell receptor (TCR) activation and inhibited the TCR-induced upregulation of Pgp, CD8, and PD-1 surface markers, suggesting its interference with activation-associated differentiation. At these same concentrations, ruxolitinib also impaired CCL19-directed transmigration of CTLs across human umbilical vein endothelial cell (HUVEC) monolayers, indicating disruption of lymphoid homing cues. Collectively, these findings demonstrate that ruxolitinib modulates Pgp at both the transcriptional and functional levels, with distinct concentration dependence. The ability of ruxolitinib to alter CTL activation and migration at clinically relevant plasma concentrations highlights the need for careful evaluation of JAK inhibitor–mediated immunomodulation and its implications for vaccination, transplantation, and T cell-based immunotherapies. Full article

In recent years, one of the most important issues in public health is the rapid growth of antibiotic resistance among pathogens. Multidrug-resistant (MDR) strains (mainly Enterobacteriaceae and non-fermenting bacilli) cause severe infections, against which commonly used pharmaceuticals are ineffective. Therefore, there is an urgent need for new treatment options and drugs with innovative mechanisms of action. Natural compounds, especially alkaloids, are showing promising potential in this area. This review focuses on the ability of the isoquinoline alkaloid berberine (BRB) to overcome various resistance mechanisms against conventional antimicrobial agents. BRB has demonstrated significant activity in inhibiting efflux pumps of the RND (Resistance-Nodulation-Cell Division) family, such as MexAB-OprM (P. aeruginosa) and AdeABC (A. baumannii). Moreover, BRB was able to decrease quorum sensing activity in both Gram-positive and Gram-negative pathogens, resulting in reduced biofilm formation and lower bacterial virulence. Additionally, BRB has been identified as a potential inhibitor of FtsZ, a key protein responsible for bacterial cell division. Particularly noteworthy, though requiring further investigation, are reports suggesting that BRB might inhibit β-lactamase enzymes, including NDM, AmpC, and ESβL types. The pleiotropic antibacterial actions of BRB, distinct from the mechanisms of traditional antibiotics, offer hope for breaking bacterial resistance. However, more extensive studies, especially in vivo, are necessary to fully evaluate the clinical potential of BRB and determine its practical applicability in combating antibiotic-resistant infections. Full article

Helicobacter pylori is a Gram-negative bacterium that infects almost half of the global population and is linked to gastric conditions like peptic ulcers and gastric cancer, as well as other diseases such as neurological disorders, cardiovascular problems, and iron deficiency anemia. Its survival in the acidic stomach environment is due to virulence factors like urease, flagella, and adhesion proteins (BabA, SabA). Current treatments involve a combination of antibiotics (clarithromycin, metronidazole, amoxicillin, tetracycline) and proton pump inhibitors, but increasing antibiotic resistance, especially to clarithromycin and metronidazole, poses a major challenge. Resistance mechanisms include mutations in drug targets, efflux pump overexpression, and enzymatic degradation of antibiotics. This has prompted exploration of alternative therapies targeting bacterial processes like urease activity, biofilm formation, and metabolic pathways (energy production, amino acid synthesis, iron acquisition). Natural compounds, such as chitosan and plant extracts, show promise in combating H. pylori growth and virulence. Vaccine development is also ongoing, with DNA vaccines showing potential for broad immune responses. However, no vaccine is yet close to widespread clinical use. Full article

Phase-separated membraneless biomolecular condensates in the cytoplasm and nucleus are now recognized to play a major role in modulating diverse functions in mammalian cells, and contribute to cancer pathogenesis through dysregulated function of condensates of transcription factors such as STAT3 and fusion oncoproteins. Oral cancer, the sixth most prevalent malignancy worldwide, in the absence of overt causes such as tobacco or alcohol, most frequently occurs in a U-shaped zone (floor of mouth, side of tongue, anterior fauces and retromolar region) reflecting the path of liquid transit through the mouth. The cellular basis for this “high-risk” zone and the biochemical mechanisms used by oral cells to combat repetitive tonicity and temperature stresses are incompletely understood. We had previously observed that at 37 °C, in OECM1 oral carcinoma cells, cytoplasmic condensates of antiviral human GFP-MxA GTPase disassembled within 1–2 min of exposure of cells to saliva-like one-third hypotonicity, and underwent “spontaneous” reassembly in the next 5–7 min. Moreover, hypotonic beverages (water, tea, coffee), investigated at 37 °C, triggered this condensate cycling. In the present studies we investigated whether this process was temperature sensitive, representative of cold vs. warm drinks. We observed a slowing of this cycle at 5 °C, and speeding up at 50 °C. The involvement in this disassembly/reassembly process of WNK-SPAK/OSR1 serine-threonine kinase pathway, best studied for regulation of water and Na, K and Cl influx and efflux in kidney tubule cells, was evaluated by us in oral cells using pathway inhibitors WNK463, WNK-IN-11 and closantel. The pan-WNK inhibitor WNK463 inhibited hypotonicity-driven condensate disassembly, while the SPAK/OSR1 inhibitor closantel markedly slowed reassembly. Unexpectedly, the WNK1-selective inhibitor (WNK-IN-11), triggered a dramatic and rapid (within 1 h) spheroid to fibril transition of GFP-MxA condensates in live cells, but without affecting MxA antiviral function. The new data suggest a novel hypothesis for the anatomic localization of oral cancer in the U-shaped “high-risk” zone in the mouth: dysfunction of biomolecular condensates in oral cells along the beverage transit pathway through the mouth due to repetitive tonicity and temperature stresses that might underlie a prooncogenic progression. Full article

Background: Tariquidar (Tq) is an inhibitor of the multidrug resistance (MDR) proteins relevant to ATP-binding cassette transporters (ABC transporters), which suppresses the ATP-dependent efflux of a variety of hydrophilic and amphipathic compounds, including anticancer drugs. Tq is a representative of a new generation of MDR inhibitors with high affinity to ABC proteins. However, there are still no data on the possible effect of Tq on mitochondria as an important target in the regulation of cell death or survival. Methods: We investigated the influence of Tq on the Ca²⁺-dependent mitochondrial permeability transition pore (mPTP). The effect of Tq was assessed using several parameters, including the calcium load, membrane potential, and mitochondrial swelling. To evaluate the specific targets of Tq, selective inhibitors of components of the mitochondrial pore were used, including adenine nucleotides, carboxyatractylozide (Catr) and bongkrekic acid (BA), oligomycin, and cyclosporine A. Results: Tq decreased the calcium retention capacity, activated mitochondrial swelling, and lowered the influence of ADP and ATP, the inhibitors of the Ca²⁺-induced pore opening, at their low concentrations. These effects of Tq were observed in both calcium-load and swelling assays, thus mimicking the effect of Catr, a selective inhibitor of adenine nucleotide translocase (ANT). Tq also decreased the protective effect of BA, an inhibitor of ANT and mPTP, on the calcium retention capacity of mitochondria. Further, Tq dose-dependently decreased the inhibitory effect of a low ATP concentration but not of high concentrations, at which the effect of Tq was activated by oligomycin, an inhibitor of F-ATP synthase. Conclusions: The influence of Tq extends to mitochondria, specifically to the regulation of membrane permeability, promoting the activation of pore opening, probably through an interaction with ANT, a component of the pore-forming complex. The effect of Tq on the opening of mPTP is strongly dependent on the concentrations of adenine nucleotides and, consequently, on the functional state of mitochondria. The direct influence of Tq on mitochondria can be considered as a new activity that promotes the sensitization of cells to various treatments and stimuli. Full article

Drug resistance is still one of the main challenges for the treatment of colorectal cancer (CRC). Whilst some resistance mechanisms are well known, from the static therapy success rate, clearly, still much is undiscovered. Intracellular transport mechanisms have attracted attention as having a possible role in drug resistance, and here, the Endosomal Sorting Complex Required for Transport (ESCRT) protein family is studied as a source of drug resistance modulation using human CRC cell lines and clinical material. From an initial screening of ESCRT proteins in a panel of 10 CRC wild-type cell lines using immunoblotting, Vacuolar Protein Sorting-Associated Protein A4 (VPS4A) was identified as being consistently highly expressed, and it was selected for further investigation. Immunohistopathological evaluation in a small panel of CRC patient samples demonstrated high expression in the tumor epithelium compared to normal intestinal epithelium. The knockdown of VPS4A resulted in enhanced sensitivity of cells to oxaliplatin, and it was subsequently seen that oxaliplatin-resistant sublines had significantly higher VPS4A expression than their wild-type variants. In addition, it was demonstrated that a small molecule inhibitor of VPS4A, aloperine, could interact synergistically with oxaliplatin to enhance its sensitivity in an oxaliplatin-resistant cell line. We hypothesize from initial RNA sequencing analysis that the mechanism of action of VPS4A modulation is through depleting levels of the drug efflux transporter MRP2 in the cell, preventing oxaliplatin egress and increasing cell exposure to the drug. The evidence presented here thus indicates that ESCRT machinery, specifically VPS4A, may act as a modulator of oxaliplatin resistance in CRC. Full article