Search Results (206)

Objective: The development of natural and new P-gp modulators to reverse tumor multidrug resistance (MDR). Methods: Test compounds were prepared from the plant Metaplexis japonica, and their ability to reverse P-glycoprotein (P-gp)-mediated MDR was investigated in HepG2/Dox cells. Their effects on P-gp expression and function and their interaction modes with P-gp were also investigated. Results: Natural product 3β,12β,14β, 17β,20(S)-pentahydroxy-5α-pregnan-12β-O-(E)-cinnamate (1) and its new semisynthetic derivative 3β12β,14β,17β,20(S)-pentahydroxy-5α-pregnan-3β-O-nicotinate-12β-O-(E)-cinnamate (1a) were obtained. At non-cytotoxic concentrations of 5 or 10 μM, they significantly reversed the resistance of HepG2/Dox cells to P-gp substrate drugs doxorubicin, paclitaxel, and vinblastine, with reversal folds of 7.1, 118.5, and 198.3 (1), and 18.8, 335.8, and 140.0 (1a), respectively, at 10 μM. Cell apoptosis and expression of caspase 9 were both triggered by the combination of 10 μM of compound 1 or 1a and 500 nM of paclitaxel (p < 0.001). Compound 1 or 1a did not affect P-gp expression, but it did significantly suppress the efflux of Rhodamine 123 out of HepG2/Dox cells (p < 0.001). On the Caco-2 cell monolayer, 1 and 1a were shown to be non-substrates of P-gp, with efflux ratios of 0.83 and 0.89. Molecular docking revealed their strong binding energies (−8.2 and −8.4 kcal/mol) with P-gp, and their direct binding to P-gp was confirmed by their dissociation constants (5.53 µM for 1 and 3.72 µM for 1a), determined using surface plasmon resonance. Conclusions: Compounds 1 and 1a are potential P-gp modulators; they may reverse P-gp-MDR through interacting with P-gp to interfere with substrate binding and transporting, and have the potential to improve the efficacy of paclitaxel or vinblastine drugs for combating P-gp-mediated MDR in tumor cells. Full article

The overexpression of P-glycoprotein (P-gp) is often directly related to multidrug resistance (MDR), one of the greatest challenges in cancer treatment. This transmembrane efflux pump decreases the intracellular concentrations of chemotherapy drugs, reducing their effectiveness and resulting in treatment failure. This work used in silico methods to assess the potential of bioactive chemicals produced from mushrooms as P-gp modulators. A database comprising 211 bioactive compounds from mushrooms was investigated using molecular docking and virtual screening techniques against the P-gp structure. The compounds ergosta-4,6,8(14),22-tetraen-3-one, lucidumol A, (22E,24S)-ergosta-4,22-dien-3-one, antcin K, 3,11-dioxolanosta-8,24(Z)-diene-26-oic acid, and (22E)-19-norergosta-5,7,9,22-tetraen-3$\beta$-ol were identified as the six best candidates from our database of mushroom compounds based on their binding affinities, toxicity predictions, and pharmacological properties assessed through ADME analyses (absorption, distributions, metabolism, and excretion). These six compounds exhibited strong binding affinities, with binding energies ranging from −12.31 kcal/mol to −10.93 kcal/mol, all showing higher affinities than the control, tariquidar, which had a binding energy of −10.78 kcal/mol. Toxicity predictions indicated favorable safety profiles for all six, while ADME analyses found that all six compounds had high oral bioavailability and a low probability of acting as P-gp substrates. These results position bioactive mushroom compounds, particularly these six, as promising P-gp modulators, suggesting positive outcomes in cancer treatment. Full article

Background/Objectives: HIF-1α and ERRα are both implicated in breast cancer progression, yet their functional interplay remains poorly understood. This study investigates their molecular crosstalk in the context of hypoxia-induced drug resistance. Methods: MCF-7 (estrogen receptor, ER-positive) spheroids and CoCl₂-treated SK-BR-3 (ER-negative) cells were used to model tumor hypoxia. Protein expression, coimmunoprecipitation, chromatin immunoprecipitation (ChIP), pharmacological inhibition, and siRNA-mediated gene silencing were employed to assess physical and functional interactions. Immunohistochemistry (IHC) on a tissue microarray (TMA) of 168 invasive breast carcinomas was performed to evaluate clinical relevance. Results: ERRα levels remained unchanged under hypoxia, while its coactivator, Peroxisome Proliferator-Activated Receptor Gamma Coactivator-1 α (PGC-1α), was upregulated. ERRα physically interacted with HIF-1α and was required for HIF-1 transcriptional activity under hypoxic conditions. ChIP assays showed that ERRα-driven overexpression of Permeability glycoprotein 1 (P-gp) and Vascular Endothelial Growth Factor (VEGF) was mediated by HIF-1α binding to the MDR1 and VEGF promoters. Inhibition or silencing of ERRα reversed P-gp overexpression and restored intracellular doxorubicin. TMA analysis confirmed the clinical correlation between ERRα, HIF-1α, and P-gp expression, highlighting the role of ERRα in hypoxia-induced drug resistance. ERRα expression was independent of ER status, suggesting an estrogen-independent function. Conclusions: This study identifies a novel physical and functional interaction between ERRα and HIF-1α that promotes chemoresistance in hypoxic breast tumors. Targeting ERRα may represent a promising therapeutic strategy to overcome drug resistance in aggressive, ER-independent breast cancer subtypes. 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

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

P-glycoprotein (P-gp/ABCB1), a key ATP-binding cassette (ABC) transporter, plays a central role in multidrug resistance (MDR), one of the leading causes of chemotherapy failure in cancer treatment. P-gp actively pumps chemotherapeutic agents out of cancer cells, reducing intracellular drug concentration and compromising therapeutic efficacy. Recent advancements in structural biology, particularly cryogenic electron microscopy (cryo-EM), have revealed detailed conformational states of P-gp, providing unprecedented insights into its transport mechanisms. In parallel, studies have identified various P-gp mutants in cancer patients, many of which are linked to altered drug efflux activity and resistance phenotypes. This review systematically examines recent structural studies of P-gp, correlates known patient-derived mutations to their functional consequences, and explores their impact on MDR. We propose plausible mechanisms by which these mutations affect P-gp’s activity based on structural evidence and discuss their implications for chemotherapy resistance. Additionally, we review current approaches for P-gp inhibition, a critical strategy to restore drug sensitivity in resistant cancers, and outline future research directions to combat P-gp-mediated MDR. Full article

Background/Objectives: The ineffective delivery of drugs into tumors and the existence of multidrug resistance (MDR) are the primary causes of chemotherapy failure. Downregulation of the Sonic Hedgehog (Shh) pathway has been shown to reduce P-glycoprotein (P-gp) expression on cell membranes and to resist MDR. Methods: In this study, we combine cyclopamine (CYP, a potent Shh antagonist) with paclitaxel (PTX, an antitumor drug that can produce MDR) in a nano-drug delivery system (CYP NP and PTX NP) for the treatment of drug-resistant breast cancer. Nanoparticles were characterized for size, zeta potential, and encapsulation efficiency. P-gp expression, nanoparticle accumulation, cytotoxicity, and apoptosis were evaluated in MCF-7 and MCF-7/Adr cells. Penetration ability was assessed using 3D multicellular tumor spheroids. Antitumor efficacy and nanoparticle biodistribution were validated in MCF-7/Adr-bearing nude mice models. Results: Our engineered CYP nanoparticles (~200 nm) demonstrated prolonged intratumoral retention, enabling sustained Shh pathway inhibition and P-gp functional suppression. This size-optimized formulation created a favorable tumor microenvironment for the smaller PTX nanoparticles (~30 nm), facilitating deeper tumor penetration and enhanced cellular uptake. Meanwhile, by down-regulating P-gp expression, CYP NPs could convert drug-resistant cells to PTX-sensitive cells in both cytotoxicity and apoptosis induction through the Shh pathway. The combination of CYP NP and PTX NP augmented the antitumor effects in MCF-7/Adr-bearing nude mice models. Conclusions: The CYP NP and PTX NP combination offers a new therapeutic strategy in cancer treatment. 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/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

Background/Objectives: This study explores the potential of LB-100 (a protein phosphatase 2A—PP2A inhibitor) combined with adavosertib (a WEE1 kinase inhibitor) and doxorubicin (DOX), to overcome multidrug resistance (MDR) in cancer cells and enhance treatment efficacy. Methods: We evaluated LB-100 combinations with adavosertib and DOX in patient-derived glioblastoma and non-small cell lung carcinoma cells (NSCLCs) using a real-time cell analyzer. Effectiveness was also assessed through immunofluorescence assay, and interactions were analyzed via SynergyFinder+. We also examined P-glycoprotein (P-gp) expression and drug resistance genes’ expression in MDR glioblastoma and NSCLCs after LB-100 treatment, as well as LB-100 sensitizing effect on DOX and DOX accumulation. Results: LB-100 significantly boosts the effectiveness of adavosertib and DOX after multiple applications. It also enhances these drugs’ cytotoxicity in a single application without acting synergistically. Additionally, LB-100 reduces P-gp expression in MDR glioblastoma and NSCLCs, sensitizing them to DOX and increasing its accumulation. Conclusions: LB-100 enhances the effectiveness of drugs against MDR cancer cells, presenting a promising strategy to overcome drug resistance in glioblastoma and NSCLCs through P-gp modulation. Full article

Chemotherapy resistance is a significant barrier to effective cancer treatment. A key mechanism of resistance at the single-cell level is the overexpression of drug transporters in the ABC family, particularly P-glycoprotein (P-gp), which leads to multidrug resistance (MDR). Inhibitors of these transporters can help re-sensitize cancer cells to chemotherapeutics. This study evaluated elacridar (GG918 and GF120918), a potent third-generation P-gp inhibitor, for its ability to reverse MDR in paclitaxel (PAC)-resistant ovarian cancer cell lines. Sensitive and PAC-resistant cells were cultured in two-dimensional (2D) and three-dimensional (3D) models. MDR1 gene expression was analyzed using Q-PCR, and P-gp protein expression was examined via Western blot and immunofluorescence. Drug sensitivity was evaluated with MTT assays, and P-gp activity was analyzed by flow cytometry and fluorescence microscopy. Elacridar effectively inhibited P-gp activity and increased sensitivity to PAC and doxorubicin (DOX) in 2D cultures but not cisplatin (CIS). In 3D spheroids, P-gp activity inhibition was observed via Calcein-AM staining. However, no re-sensitization to PAC occurred and limited improvement was observed for DOX. These findings suggest that elacridar effectively inhibits P-gp in both 2D and 3D conditions. However, its ability to overcome drug resistance in 3D models is limited, highlighting the complexity of tissue-specific resistance mechanisms. Full article

Multidrug resistance (MDR) development against cytotoxic drugs by tumor cells is one of the main causes of treatment failure in gastrointestinal cancers, a group of cancers of great relevance due to their prevalence and/or mortality. This phenomenon is mediated by diverse mechanisms, including the overexpression of members of the superfamily of membrane transporters of the ATP-binding cassette (ABC). Most of these molecules, including P-glycoprotein (P-gp or MDR1/ABCB), MDR-associated protein 1 (MRP1/ABCC1), MRP2, and breast cancer resistance protein (BCRP/ABCG2), are integrated in the cell membrane, acting as drug efflux pumps. Despite the use of various MDR modulators as adjuvants to improve the chemotherapy response, the results have not been satisfactory. Natural products from plants, such as flavonoids, alkaloids, terpenoids, and coumarins, are capable of modifying drug resistance, suggesting an improvement in the antitumoral effect of the current treatments without generating side effects. This review aims to provide an overview of the most recent studies in relation to plant-derived molecules and extracts that modulate resistance to antitumor drugs and that could be applied in the future in clinical practice to improve the treatment of patients with gastrointestinal cancer. Full article

Algae have great therapeutic value and have attracted a great deal of attention due to the abundance of bioactive compounds they contain, which may be the key to fighting diseases of various origins, such as skin cancer, breast cancer, or osteosarcoma. In this regard, global trends indicate that cancer is likely to become the leading cause of death and the main obstacle to increased life expectancy in the 21st century, which is related to multiple factors, including the various effects of climate change, which will continue to cause afflictions to human health. Then, excess exposure to ultraviolet radiation (UVR) causes damage to DNA, proteins, enzymes, and various cellular structures and leads to the development of cancer, premature aging of the skin (wrinkles, dryness, dilation of blood vessels, and loss of collagen and elastin), or alterations of the immune system. In addition, multidrug resistance (MDR) is characterized by the overexpression of efflux pumps, such as P-glycoprotein or P-gp, that expel chemotherapeutic drugs out of the cancer cell being the main obstacle to their efficacy. Some molecules inhibit efflux pumps when co-administered with antineoplastic agents, such as glycolipids. Mycosporin-like amino acids and glycolipids isolated from Sargassum have shown an important role as potential anticancer agents. The results show that glycolipids and mycosporin-like amino acids present in brown algae of the genus Sargassum exhibit cytotoxic effects on different types of cancer, such as breast cancer, leukemia, and osteosarcoma, which is a key criterion to be considered as a natural anti-cancer strategy; but, more in-depth in vitro studies are needed to represent them at the in vivo level, as well as their validation in preclinical assays. Full article

The MCF-7R breast cancer cell line, developed by treating the parental MCF-7 cells with increasing doses of doxorubicin, serves as a model for studying acquired multidrug resistance (MDR). MDR is a major challenge in cancer therapy, often driven by overexpression of the efflux pump P-glycoprotein (P-gp) and epigenetic modifications. While many P-gp inhibitors show promise in vitro, their nonspecific effects on the efflux pump limit in vivo application. Curcumin, a natural compound with pleiotropic action, is a nontoxic P-gp inhibitor capable of modulating multiple pathways. To explore curcumin’s molecular effects on MCF-7R cells, we analyzed the expression of genes involved in DNA methylation and transcription regulation, including ABCB1/MDR1. Reduced representation bisulfite sequencing further unveiled key epigenetic changes induced by curcumin. Our findings indicate that curcumin treatment not only modulates critical cellular processes, such as ribosome biogenesis and cytoskeletal dynamics, but also reverses the resistant phenotype, toward that of sensitive cells. This study highlights curcumin’s potential as an adjuvant therapy to overcome chemoresistance, offering new avenues for pharmacological strategies targeting epigenetic regulation to re-sensitize resistant cancer cells. Full article