Search Results (255)

Carfilzomib (CFZ) is a cornerstone in the treatment of relapsed multiple myeloma (MM). However, its efficacy is limited by resistance mediated by the overexpression of the ABC-transporter P-glycoprotein (P-gp). The signaling pathways driving the emergence of P-gp in MM remain unclear. To investigate this, we generated CFZ-resistant AMO-1/CFZ cells with P-gp overexpression by long-term selection. RNA sequencing of control AMO-1 and AMO-1/CFZ, sorted into two subpopulations, P-gp HIGH and P-gp LOW, implicated the Ras/MEK/ERK pathway as the most likely signaling cascade involved in P-gp upregulation. We therefore evaluated two clinically used MAPK pathway inhibitors, cobimetinib and ulixertinib, for their ability to re-sensitize AMO-1/CFZ cells to CFZ. Co-administration at non-toxic concentrations enhanced sensitivity 5-fold with cobimetinib and 17-fold with ulixertinib. Analysis of the combined MTT assay results, rhodamine efflux experiments, molecular docking, and Western blotting revealed distinct actions. Ulixertinib primarily functions as a potent direct P-gp inhibitor. Conversely, non-toxic concentrations of cobimetinib sensitizes cells by suppressing MAPK signaling, though it also exhibits P-gp inhibition at higher concentrations. At the IC₅₀ concentration, both inhibitors reduced P-gp expression. In conclusion, combining CFZ with MAPK pathway inhibitors like cobimetinib or ulixertinib represents a promising strategy to overcome P-gp-mediated resistance in MM. Full article

Background: Multidrug resistance (MDR), primarily driven by P-glycoprotein (P-gp)-mediated drug efflux, presents a significant challenge in cancer therapy, contributing to chemotherapy failure and poor patient outcomes. Objectives: In this study, we explored the potential of manidipine (MA), a clinically approved calcium channel blocker, to reverse P-gp-mediated MDR through modulation of calcium signaling via nuclear factor of activated T cells 2 (NFAT2). Methods: Paclitaxel (PTX) resistance ABCB1-overexpressing cancer in vitro and in vivo were used for evualting the anti-MDR effects of MA, as well as the underlying mechanism with siRNA of NFAT2. Results: We found that MA at non-toxic concentrations (0.6–5.4 μM) significantly sensitize drug-resistant colorectal (HCT-8/T) and non-small cell lung (A549/T) cells to PTX, reducing its IC₅₀ by up to 1328-fold in vitro models. Mechanistically, MA inhibited P-gp efflux activity without altering its expression, as shown by an increased intracellular accumulation of doxorubicin and Flutax-2 (2.3- and 3.1-fold, respectively) and dose-dependent modulation of ATPase activity (EC₅₀ = 4.16 μM). Notably, MA reduced intracellular calcium levels (52% reduction, p < 0.001) and downregulated NFAT2, an oncogene overexpressed in resistant cells. In vivo, MA (3.5 mg/kg) synergizes with PTX to inhibit tumor growth by 68% (p < 0.001) in A549/T xenograft model, without an observable decrease in weight. Conclusions: In sum, all these results position MA as a novel NFAT2 inhibitor to overcome P-gp-mediated MDR via modulating calcium signaling, which points to further investigation for its clinical applications. Full article

This study investigated the protective effects of Gardenia jasminoides Ellis polysaccharides (GP) on lipopolysaccharide (LPS)-induced immunosuppression and oxidative stress in mice and explored how GP modulates macrophage polarization through the TLR4/NF-κB signaling axis. The results showed that GP notably restored thymus and spleen indices in LPS-treated mice, markedly decreased the serum concentrations of malondialdehyde, and enhanced superoxide dismutase activity and total antioxidant capacity. In RAW 264.7 macrophage cultures, GP displayed immunostimulatory effects by improving phagocytic activity, promoting NO synthesis, and enhancing the secretion of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α. These effects were observed in cells not pretreated with TAK-242 or PDTC; however, they were not observed in cells pretreated with these inhibitors. At 300 µg/mL concentration, GP markedly enhanced the transcriptional levels of iNOS and cytokine genes. Protein analysis revealed significant upregulation of TLR4, MyD88, TRAF6, NF-κB RelA/p65, and phosphorylated p65. Fluorescence imaging confirmed the nuclear translocation of p65. Collectively, these findings indicated that GP reversed systemic immunosuppression and oxidative stress, offering foundational insights for developing natural immune regulators. The observed immunomodulatory properties of GP are likely mediated through the TLR4/NF-κB signaling pathway. Full article

We explored the pharmacology of the P-glycoprotein (P-gp) efflux pump and its role in multidrug resistance. We used Protein Data Bank (PDB) database mining and the artificial intelligence (AI) model Boltz-2.1.1, developed for simultaneous structure and affinity prediction, to explore the multimeric nature of recent P-gp inhibitors. We construct a MARTINI coarse-grained (CG) force field description of P-gp embedded in a model of the endothelial blood–brain barrier. We found that recent P-gp inhibitors have been captured in either monomeric, dimeric, or trimeric states. Our CG model demonstrates the ability of P-gp substrates to permeate and transition across the BBB bilayer. We report a multimodal binding model of P-gp inhibition in which later generations of inhibitors are found in dimeric and trimeric states. We report analyses of P-gp substrates that point to an extended binding surface that explains how P-gp can bind over 300 substrates non-selectively. Our coarse-grained model of substrate permeation into membranes expressing P-gp shows benchmarking similarities to prior atomistic models and provide new insights on far longer timescales. Full article

Background/Objectives: P-glycoprotein (P-gp), an ATP-binding cassette (ABC) transporter, plays a key role in multidrug resistance by actively exporting chemotherapeutic agents and xenobiotics from cells. Overexpression of P-gp significantly reduces intracellular drug accumulation and compromises treatment efficacy. Despite extensive research, clinically approved P-gp inhibitors remain elusive due to toxicity, poor specificity, and limited efficacy. This study investigates DMH1, a selective type I BMP receptor inhibitor, as a novel P-gp inhibitor. Methods: DMH1 cytotoxicity was assessed in P-gp-overexpressing (PC3-TxR, K562/Dox) and P-gp-deficient (PC3) cell lines using MTT assays. P-gp inhibition was evaluated using calcein AM retention and daunorubicin (DNR) accumulation assays. Kinetic analysis determined DMH1’s effect on P-gp-mediated transport (Vmax and Km). ATPase activity assays were performed to assess DMH1’s impact on ATP hydrolysis. Preliminary molecular docking (CB-Dock2) was used to predict DMH1’s binding site on the human P-gp structure (PDB ID: 6QEX). Results: DMH1 showed no cytotoxicity in P-gp-overexpressing or deficient cells. It significantly enhanced intracellular accumulation of Calcein AM and DNR, indicating effective inhibition of P-gp function. Kinetic data revealed that DMH1 reduced Vmax without affecting Km, consistent with noncompetitive, allosteric inhibition. DMH1 also inhibited ATPase activity in a dose-dependent manner. Docking analysis suggested DMH1 may bind to an allosteric site in the transmembrane domain, potentially stabilizing the inward-facing conformation. Conclusions: DMH1 is a promising noncompetitive, allosteric P-gp inhibitor that enhances intracellular drug retention without cytotoxicity, supporting its potential as a lead compound to overcome multidrug resistance and improve chemotherapeutic efficacy. Full article

Objectives: High-calorie diets are linked to increased risks of chronic inflammation and immune dysfunction, yet their role in modulating pneumonia severity remains unclear. Focusing on the interactions among gut-originating short-chain fatty acids (SCFAs), neutrophil function, and histone deacetylases (HDACs), this research examined the exacerbating effects of a high-calorie diet on pneumonia in rats. Methods: Male Sprague-Dawley rats (3 weeks old, 110 ± 10 g) were allocated among four groups: normal diet (N), high-calorie diet (G), LPS-induced pneumonia (P), and high-calorie diet combined with lipopolysaccharide (LPS)-induced pneumonia (GP). LPS was administered via aerosolization for three days. Fecal, serum, and lung SCFA levels were quantified via GC-MS. Neutrophil extracellular traps (NETs) formation, neutrophil apoptosis, and HDAC activity were assessed using immunofluorescence, TUNEL assays, and qRT-PCR. Propionate supplementation and HDAC inhibitor (trichostatin A) interventions were applied to validate mechanistic pathways. Results: The group GP exhibited exacerbated lung inflammation, increased NETs release, and reduced neutrophil apoptosis compared to the group P. Propionate levels in feces, serum, and lung tissues decreased sharply in GP rats, correlating with elevated HDAC1/2/3/6 activity and reduced histone acetylation. Propionate supplementation or HDAC inhibition significantly attenuated lung injury, suppressed NETs, and restored neutrophil apoptosis. Conclusions: High-calorie diets exacerbate pneumonia by depleting gut-derived propionate, which drives HDAC-mediated NETs overproduction and impairs neutrophil apoptosis. Restoring propionate levels or targeting HDACs may offer therapeutic strategies for diet-aggravated respiratory diseases. Mechanistically, propionate-mediated HDAC inhibition demonstrates proof-of-concept efficacy in modulating H4 acetylation, warranting further investigation in disease-specific pneumonia models. 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

Objectives: The anticancer effects of PI3Kα inhibitors (PI3Ki) are constrained by their hyperglycemic side effects, while the efficacy of conventional hypoglycemic agents, such as insulin, metformin, and SGLT-2 inhibitors, in mitigating PI3Ki-induced hyperglycemia remains suboptimal. Dorzagliatin, a novel glucokinase activator, has been approved in China for the management of hyperglycemia, offering a promising alternative. This study aims to investigate the pharmacokinetic properties and potential mechanisms of drug interactions of dorzagliatin in the regulation of PI3K-induced hyperglycemia. Methods: Plasma concentrations of WX390, BYL719, and Dorz in mice were measured using high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Pharmacokinetic (PK) parameters and PK/PD models were derived by using Phoenix WinNonlin 8.3.5 software. Blood glucose levels at various time points and tumor volume changes over a four-week period were assessed to explore the interactions when PI3Ki were combined with dorzagliatin. Results: The results indicated that, compared to the Dorz group, the combination groups (Dorz + BYL719, Dorz + WX390) exhibited increases in ${\mathrm{A}\mathrm{U}\mathrm{C}}_{0\to t}$ of dorzagliatin by 41.65% and 20.25%, and in C_max by 33.48% and 13.32%, respectively. In contrast, co-administration of these PI3Ki with dorzagliatin resulted in minimal increase in their plasma exposure. The combination therapy group (Dorz+BYL719) exhibited superior antitumor efficacy compared to the BYL719 group. Conclusions: Our findings indicate that the drug–drug interactions (DDIs) between dorzagliatin and multiple PI3Ki (including WX390 and BYL719) may partially account for the enhanced antitumor efficacy observed in the combination therapy group compared to PI3Ki monotherapy. This interaction may be explained by the inhibition of P-glycoprotein (P-gp) and the pharmacological mechanism of dorzagliatin regarding the activation of insulin regulation. Full article

Chemotherapy resistance is a major obstacle in the treatment of ovarian cancer, often resulting in disease recurrence and poor prognosis for patients. A key contributor to this resistance is the overexpression of ATP-binding cassette (ABC) transporters, including breast cancer resistance protein (BCRP/ABCG2), which actively effluxes chemotherapeutic agents such as topotecan (TOP) or mitoxantrone (MIT), limiting their intracellular accumulation and efficacy. This study investigated the potential of elacridar (GG918), a potent dual P-gp and BCRP inhibitor, to overcome drug resistance in ovarian cancer cell lines. Both TOP-sensitive and TOP-resistant ovarian cancer cells were grown in two-dimensional (2D) monolayers and three-dimensional (3D) spheroid models to better mimic the tumor microenvironment. The expression of the ABCG2 gene was quantified via qPCR and BCRP protein levels were assessed by western blotting and immunofluorescence. Drug response was evaluated using MTT viability assays, while BCRP transporter activity was examined using flow cytometry and microscopic assessment of the intracellular retention of BCRP fluorescent substrates (Hoechst 33342 and MIT). In both 2D and 3D cultures, elacridar effectively inhibited BCRP function and significantly enhanced sensitivity to TOP. These findings suggest that elacridar can inhibit BCRP-mediated drug resistance in ovarian cancer cell models. Full article

Multidrug resistance (MDR) poses a significant challenge in cancer therapy, often leading to treatment failure and relapse. ATP-binding cassette (ABC) transporters, particularly ABCG2, play a pivotal role in MDR development by actively expelling chemotherapeutic agents from cancer cells. This study investigates the effects of two groups of primaquine derivatives—fumardiamides (1a–d) and bis-ureas (2a, b), both bearing halogenated benzene rings—on the activity of P-glycoprotein (P-gp) and ABCG2. Their potential to reverse MDR was evaluated through a series of functional assays aimed at comparing transporter–compound interactions. The results indicated that fumardiamide derivatives, specifically 1a, 1b, and 1d, exhibited potent inhibition of ABCG2 while having no effect on P-gp, demonstrating a selective mode of action. The tested derivatives displayed low to moderate cytotoxicity and did not affect ABCG2 expression or localization. Moreover, these compounds enhanced the sensitivity of drug-resistant cancer cell lines to mitoxantrone, underscoring their potential to overcome ABCG2-mediated MDR. These findings suggest that chemical modifications of primaquine, particularly the incorporation of fumardiamide moieties, confer novel biological properties, providing promising leads for the development of selective ABCG2 inhibitors. Full article

P-glycoprotein (P-gp), a transmembrane efflux pump encoded by the ABCB1/MDR1 gene, is a major contributor to multidrug resistance in hematological malignancies. These malignancies, arising from hematopoietic precursors at various differentiation stages, can manifest in the bone marrow, circulate in the bloodstream, or infiltrate tissues. P-gp overexpression in malignant cells reduces the efficacy of chemotherapeutic agents by actively expelling them, decreasing intracellular drug concentrations, and promoting multidrug resistance, a significant obstacle to successful treatment. This review examines recent advances in combating P-gp-mediated resistance, including the development of novel P-gp inhibitors, innovative drug delivery systems (e.g., nanoparticle-based delivery), and strategies to modulate P-gp expression or activity. These modulation strategies encompass targeting relevant signaling pathways (e.g., NF-κB, PI3K/Akt) and exploring drug repurposing. While progress has been made, overcoming P-gp-mediated resistance remains crucial for improving patient outcomes. Future research directions should prioritize the development of potent, selective, and safe P-gp inhibitors with minimal off-target effects, alongside exploring synergistic combination therapies with existing chemotherapeutics or novel agents to effectively circumvent multidrug resistance in hematological malignancies. Full article

Background/Objectives: Gastrointestinal stromal tumors (GISTs) are rare mesenchymal tumors of the gastrointestinal (GI) tract, predominantly driven by KIT or PDGFRα oncogene mutations. Nonspecific symptoms contribute to diagnostic delays, with general practitioners (GPs) playing a pivotal role in early detection. However, studies on GIST-specific primary care pathways are limited. This study examines GP contacts, diagnoses, and prescribed drugs in primary care during the 12 months preceding GIST diagnosis. Methods: This case-control study utilized data from the Netherlands Cancer Registry and Nivel Primary Care Database. It included 294 GIST patients diagnosed between 2010 and 2020 and 576 matched cancer-free controls. GP contacts, diagnoses, and newly prescribed drugs were analyzed across two time intervals: 0–4 and 5–12 months prediagnosis. Statistical comparisons were conducted using the Wilcoxon rank-sum test and descriptive analyses. Results: GIST cases had a median of six GP contacts (IQR 4–11) in the 12 months prediagnosis versus three (IQR 2–6) for controls (p < 0.05). Contacts increased 4 months before diagnosis, peaking 1 month prior. Common diagnoses in the 4-month interval included malignant neoplasms of the stomach (27.9%) and other digestive sites (27.6% and 11.2%), abdominal pain (9.5%), and iron deficiency anemia (9.5%). Newly prescribed drugs included proton pump inhibitors (13.9%) and osmotically acting laxatives (15.0%). Conclusions: This study highlights increased GP visits and specific reasons for these visits before GIST diagnosis. Future research should further examine GP records, not only through coded data but also unstructured data, and incorporate patient and GP perspectives to explore potential improvements in the diagnostic process. Full article

The compound CNI1, identified as a novel antitumor agent based on the cytisine N-isoflavones scaffold, and its series of cytisine N-isoflavones derivatives (CNI2, CNI3, and CNI4), were first isolated from bitter bean seeds, a traditional Chinese medicinal source, by our research team. Cellular activity assays combined with virtual screening targeting P-gp revealed that CNI1, along with the three cytisine N-isoflavones derivatives, CNI2, CNI3, and CNI4, exhibited significant multidrug resistance (MDR) reversal activity in breast cancer. Despite this promising outcome, the precise molecular mechanisms and key targets involved in the MDR reversal of these compounds remain to be elucidated. To explore potential mechanisms, targets for CNI1, CNII2, CNI3, and CNI4 (CNI1-4) were predicted using SwissTargetPrediction and Pharmmapper databases, while MDR-related targets in breast cancer were retrieved from OMIM and GeneCards. The overlapping targets were utilized to construct a protein–protein interaction (PPI) network to identify core targets. Additionally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted using the DAVID database to identify relevant signaling pathways. Molecular docking simulations were employed to evaluate the binding sites and energies of CNI1-4 with the identified key targets, with the highest binding energy complexes selected for subsequent molecular dynamics simulations. This study identified 81 intersecting multidrug resistance (MDR) targets and 19 core targets in breast cancer. GO and KEGG pathway enrichment analyses revealed that MDR was primarily mediated by genes involved in cellular processes, apoptosis, protein phosphorylation, as well as the MAPK and PI3K-Akt signaling pathways. Molecular docking studies demonstrated that the binding energies of P-gp, AKT1, and SRC to CNI1-4 were all lower than −10 kcal/mol, indicating strong binding affinities. Molecular dynamics simulations further confirmed the stable and favorable binding interactions of CNI1-4 with AKT1 and P-gp. This study provides preliminary insights into the potential targets and molecular mechanisms of cytisine N-isoflavones compounds in reversing MDR in breast cancer, offering crucial data for the pharmacological investigation of CNI1-4 and supporting the development of P-gp inhibitors. Full article

Background: Antidepressants are a class of pharmaceuticals utilized for the management of many psychiatric disorders, including depression. A considerable number of antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs), have been documented to demonstrate significant anticancer properties in various cancer cell lines. Objectives: The aim of this study was to evaluate the selective cytotoxic and apoptotic effects of escitalopram oxalate (ES) alone and in combination with etoposide (ET) on ET-resistant A549 (A549/90E) lung cancer cells. Methods: The cytotoxic effects of the drugs were determined by CCK-8, trypan blue, and neutral red assays. Apoptosis was observed by Annexin V fluorescein isothiocyanate (FITC)/PI and mitochondrial membrane potential (ΔΨm) assays. Moreover, the effects of the drugs, alone and in combination, on apoptosis-related proteins, caspase-3, PTEN, and resistance-related P-gP were determined by ELISA. The relationship between drugs and lung cancer was determined with protein–protein interaction (PPI) network analysis. Results: Our results revealed that ES significantly exerted cytotoxic effects on both wild-type and A549/90E cells compared with BEAS-2B cells. The IC₅₀ values of 48.67 and 51.6 μg/mL obtained for ET and ES, respectively, at the end of 24 h of incubation for A549 cells were applied reciprocally for each cell by including BEAS-2B together with the 2xIC₅₀ and ½ IC₅₀ values. The results of each combination were statistically evaluated with combination indices (CIs) obtained using the Compusyn synergistic effect analysis program. Combination doses with a synergistic effect in A549 and A549/90E cells and an antagonistic effect in BEAS-2B cells have been determined as ½ IC₅₀ for ET and ½ IC₅₀ for ES. ET ½ IC₅₀, ES ½ IC₅₀, and an ET ½ IC₅₀ + ES ½ IC₅₀ combination caused 18.37%, 55.19%, and 57.55% death in A549 cells, whereas they caused 44.9%, 22.4%, and 51.94% death in A549/90E cells, respectively. In A549 cells, the combination of ES ½ IC₅₀ and ET ½ IC₅₀ caused increased levels of caspase-3 (p < 0.01) and P-gP (p < 0.001), while PTEN levels remained unchanged. The combination resulted in an increase in caspase-3 (p < 0.001) and PTEN (p < 0.001) amounts, alongside a decrease in P-gP (p < 0.01) levels in A549/90E cells. The death mechanism induced by the combination was found to be apoptotic by Annexin V-FITC and ΔΨm assays. Conclusions: Based on our findings, ES was observed to induce cytotoxic and apoptotic activities in A549/90E cells in vitro. ES in combination therapy is considered to be effective to overcome ET resistance by reducing the amount of P-gP in A549/90E cells. Full article

Background/Objectives: Multidrug resistance is one the leading problems in cancer treatment, where the overexpression of P-gp and other drug efflux pumps is regarded as the primary cause. With the intention to develop transporter inhibitors, natural products such as phenolics have shown great potential and diverse attention recently. Among these, isorhamnetin (ISO), an O-methylated flavonol, is predominantly found in the fruits and leaves of various plants. Thus, this study aimed to investigate the effects of ISO on the mRNA expression of membrane transporters P-gp, BCRP, MRP 1, 2, and 5, the protein expression of P-gp, as well as the GSTP1 and GSH content in DLD1 and HCT-116 colon cancer cells. Methods: The cytotoxic effect of isorhamnetin is assessed using an MTT test, while qPCR and immunocytochemistry methods were used to determine gene and protein expression levels. The concentration of reduced glutathione was determined using the colorimetric method. Results: Based on the results, ISO can modulate the expression of transporters responsible for the resistance development (all transporters on the transcriptional level were downregulated in DLD1 cells, while only MRP1 on HCT-116 cells, and reduced P-gp protein expression on both investigated cell lines). Increased glutathione content in treated cells and GSTP1 expression suggest metabolizing the ISO and potential ejection with GSH-dependent pumps. Conclusions: Thus, in future experiments, ISO as a natural medicinal compound could be used as a chemosensitizer to prevent or overcome membrane transporter-mediated drug resistance. Full article