Search Results (45)

Anthracyclines have been clinically well established in cancer chemotherapy for decades. The main limitations of this drug class are the development of resistance and severe side effects. In the present investigation, we analyzed 30 anthracyclines in a panel of 59 cell lines of the National Cancer Institute, USA. The log₁₀IC₅₀ values varied from −10.49 M (3′-deamino-3′-(4″-(3″-cyano)morpholinyl)-doxorubicin, 1) to −4.93 M (N,N-dibenzyldaunorubicin hydrochloride, 30). Multidrug-resistant NCI-ADR-Res ovarian cancer cells revealed a high degree of resistance to established anthracyclines (between 18-fold to idarubicin (4) and 166-fold to doxorubicin (13) compared to parental, drug-sensitive OVCAR8 cells). The resistant cells displayed only low degrees of resistance (1- to 5-fold) to four other anthracyclines (7, 18, 28, 30) and were even hypersensitive (collaterally sensitive) to two compounds (1, 26). Live cell time-lapse microscopy proved the cross-resistance of the three chosen anthracyclines (4, 7, 9) on sensitive CCRF/CEM and multidrug-resistant CEM/ADR5000 cells. Structure–activity relationships showed that the presence of tertiary amino functions is helpful in avoiding resistance, while primary amines rather increased resistance development. An α-aminonitrile function as in compound 1 was favorable. Investigating the mRNA expression of 49 ATP-binding cassette (ABC) transporter genes showed that ABCB1/MDR1 encoding P-glycoprotein was the most important one for acquired and inherent resistance to anthracyclines. Molecular docking demonstrated that all anthracyclines bound to the same binding domain at the inner efflux channel side of P-glycoprotein with high binding affinities. Kaplan–Meier statistics of RNA sequencing data of more than 8000 tumor biopsies of TCGA database revealed that out of 23 tumor entities high ABCB1 expression was significantly correlated with worse survival times for acute myeloid leukemia, multiple myeloma, and hepatocellular carcinoma patients. This indicates that ABCB1 may serve as a prognostic marker in anthracycline-based chemotherapy regimens in these tumor types and a target for the development of novel anthracycline derivatives. 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

Epilepsy is a prevalent neurological disorder that affects millions worldwide, with a significant portion of individuals experiencing drug-resistant forms of the condition. In Latin America, the challenge of identifying the underlying causes of multidrug-resistant epilepsy (MDRE) is particularly pressing. (1) Background: This systematic review aims to highlight the critical importance of understanding the etiology of MDRE in Latin America. (2) Methods: A systematic review of Medline (PubMed), Scopus, and Web of Science was conducted following the PRISMA methodology; articles were selected if they included information on the etiology of MDRE in Latin-American participants, and the NHLBI tool was used to assess bias. (3) Results: A total of 37 published articles were finally included in the review. The most frequently documented cause of drug-resistant epilepsy was structural, affecting 725 patients, with hippocampal atrophy and sclerosis predominantly involving both the right and left lobes. The second most common cause was genetic, identified in 362 individuals who exhibited polymorphisms in genes such as ABCB1, CYP2C9, SCN1A, SLC6A4, and MDR-1, among others. The third most frequent cause was metabolic, and the fourth was inflammatory, affecting 258 individuals, which was associated with various inflammatory markers, including IL-1β, IL-6, CD8+, CD-25, and HLA-DR. Finally, infectious causes were also reported. (4) Conclusions: Structural causes are the leading etiology of MDRE in Latin America, followed by genetic, metabolic, inflammatory, and infectious origins. The regional pattern contrasts with findings from Europe and Asia, highlighting the influence of socioeconomic, environmental, and population-specific genetic factors. Our findings underscore the urgent need for regionally tailored research and interventions, particularly in understudied areas such as infectious causes and neuroinflammation. Full article

Tree peony (Paeonia ostii T. Hong et J. X. Zhang) is an important medicinal and ornamental plant. It would be useful to propagate this plant in tissue culture, but it is difficult to induce root formation. Auxin plays a pivotal role in adventitious root formation, and ABCB transporter proteins are involved in auxin transport. To elucidate the function of the ABCB transporter family in P. ostii, we identified members of the ABCB gene family in the P. ostii genome and analyzed the functional characteristics of the putative proteins. In total, 29 ABCB genes were identified in P.ostii, distributed on five chromosomes. In a phylogenetic analysis, the PoABCBs were grouped into four subfamilies, with the largest being Subfamily I, characterized by their MDR structure. PoABCB genes in the same subfamily exhibited similar intron/exon arrangements and motif composition. The promoters of PoABCBs contained cis-acting elements associated with the photoresponse and hormone signaling. qRT-PCR analyses showed that, after treatment of tissue-cultured P. ostii seedlings with auxin, five PoABCB gene family members (PoABCB6, PoABCB10, PoABCB11, PoABCB12, and PoABCB16) were significantly upregulated during adventitious root development. These genes may play roles in the auxin response and adventitious root development of P. ostii in vitro. 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

Multidrug resistance (MDR) presents a significant challenge in modern pharmacotherapy, greatly diminishing the effectiveness of chemotherapeutic agents. A primary mechanism contributing to MDR is the overexpression of P-glycoprotein (P-gp), also known as MDR1, encoded by the ABCB1 gene, which hampers the success of cancer treatments. Plants from the Plectranthus genus (Lamiaceae) have been traditionally acknowledged for their diverse therapeutic applications. The principal diterpene from Plectranthus grandidentatus Gürke, 7α-acetoxy-6β-hydroxyroyleanone (Roy), has demonstrated anticancer properties against various cancer cell lines. Previously synthesized ester derivatives of Roy have shown improved binding affinity to P-gp. This study employs previously acquired in vitro data on the P-gp activity of Roy derivatives to develop a ligand-based pharmacophore model, highlighting critical features necessary for P-gp modulation. Utilizing these data, we predict the potential of five novel ester derivatives of Roy to modulate P-gp in vitro against resistant NCI-H460 cells. In silico structure–activity relationship (SAR) studies were conducted on 17 previously synthesized royleanone derivatives. A binary classification model was constructed, distinguishing inactive from active compounds, generating 11,016 molecular interaction field (MIF) descriptors from structures optimized at the DFT level. After variable reduction and selection, 12 descriptors were chosen, resulting in a model with two latent variables (LV), using only 34.14% of the encoded information for calibration (LV1: 26.82%; LV2: 7.32%). The activity prediction of new derivatives suggested that four of them have a high likelihood of activity, which will be validated in future in vitro biological assays. Full article

Multidrug resistance (MDR) is a process that constitutes a significant obstacle to effective anticancer therapy. Here, we examined whether unsymmetrical bisacridines (UAs) are substrates for ABC transporters and can influence their expression in human colon LS 174T and prostate DU 145 cancer cells. Moreover, we investigated the cytotoxicity and the cellular response induced by UAs in these cells. The ATPase activities of MDR1, MRP1, and MRP2 were measured using vesicles prepared from insect Sf9 cells expressing particular ABC transporters. The gene expression and protein levels were analyzed using qPCR and Western blotting. The cellular effects were studied by MTT (cytotoxicity), flow cytometry (cell cycle analysis and phosphatidylserine externalization), and fluorescence microscopy. We showed that UAs are substrates for MDR1. Importantly, they did not influence remarkably the expressions of the ABCB1, ABCC1, and ABCC2 genes and the levels of the MDR1 and PXR proteins in the studied cells. Furthermore, the cytotoxicity and the level of apoptosis triggered by UAs in LS 174T cells possessing higher expressions of metabolic enzymes were lower compared with DU 145 cells. These results indicate that during possible UA treatment, the occurrence of drug resistance could be limited, which could favor the use of such compounds as potential candidates for future studies. Full article

SOluble Resistance-related Calcium-binding proteIN (sorcin) earned its name due to its co-amplification with ABCB1 in multidrug-resistant cells. Initially thought to be an accidental consequence of this co-amplification, recent research indicates that sorcin plays a more active role as an oncoprotein, significantly impacting multidrug resistance (MDR). Sorcin is a highly expressed calcium-binding protein, often overproduced in human tumors and multidrug-resistant cancers, and is a promising novel MDR marker. In tumors, sorcin levels inversely correlate with both patient response to chemotherapy and overall prognosis. Multidrug-resistant cell lines consistently exhibit higher sorcin expression compared to their parental counterparts. Furthermore, sorcin overexpression via gene transfection enhances drug resistance to various chemotherapeutic drugs across numerous cancer lines. Conversely, silencing sorcin expression reverses drug resistance in many cell lines. Sorcin participates in several mechanisms of MDR, including drug efflux, drug sequestering, cell death inhibition, gene amplification, epithelial-to-mesenchymal transition, angiogenesis, and metastasis. The present review focuses on the structure and function of sorcin, on sorcin’s role in cancer and drug resistance, and on the approaches aimed at targeting sorcin. Full article

Previous research highlighted the involvement of the cannabinoid CB1 receptor in regulating the physiology of hepatocytes and hepatic stellate cells. The inhibition of the CB1 receptor via peripherally restricted CB1 receptor inverse agonist JD5037 has shown promise in inhibiting liver fibrosis in mice treated with CCl4. However, its efficacy in phospholipid transporter-deficiency-induced liver fibrosis remains uncertain. In this study, we investigated the effectiveness of JD5037 in Mdr2^−/− mice. Mdr2 (Abcb4) is a mouse ortholog of the human MDR3 (ABCB4) gene encoding for the canalicular phospholipid transporter. Genetic disruption of the Mdr2 gene in mice causes a complete absence of phosphatidylcholine from bile, leading to liver injury and fibrosis. Mdr2^−/− mice develop spontaneous fibrosis during growth. JD5037 was orally administered to the mice for four weeks starting at eight weeks of age. Liver fibrosis, bile acid levels, inflammation, and injury were assessed. Additionally, JD5037 was administered to three-week-old mice to evaluate its preventive effects on fibrosis development. Our findings corroborate previous observations regarding global CB1 receptor inverse agonists. Four weeks of JD5037 treatment in eight-week-old Mdr2^−/− mice with established fibrosis led to reduced body weight gains. However, contrary to expectations, JD5037 significantly exacerbated liver injury, evidenced by elevated serum ALT and ALP levels and exacerbated liver histology. Notably, JD5037-treated Mdr2^−/− mice exhibited significantly heightened serum bile acid levels. Furthermore, JD5037 treatment intensified liver fibrosis, increased fibrogenic gene expression, stimulated ductular reaction, and upregulated hepatic proinflammatory cytokines. Importantly, JD5037 failed to prevent liver fibrosis formation in three-week-old Mdr2^−/− mice. In summary, our study reveals the exacerbating effect of JD5037 on liver fibrosis in genetically MDR2-deficient mice. These findings underscore the need for caution in the use of peripherally restricted CB1R inverse agonists for liver fibrosis treatment, particularly in cases of dysfunctional hepatic phospholipid transporter. Full article

The impact of tyrosine kinase inhibitors (TKIs) on multidrug resistance (MDR) in non-small cell lung carcinoma (NSCLC) is a critical aspect of cancer therapy. While TKIs effectively target specific signaling pathways of cancer cells, they can also act as substrates for ABC transporters, potentially triggering MDR. The aim of our study was to evaluate the response of 17 patient-derived NSCLC cultures to 10 commonly prescribed TKIs and to correlate these responses with patient mutational profiles. Using an ex vivo immunofluorescence assay, we analyzed the expression of the MDR markers ABCB1, ABCC1, and ABCG2, and correlated these data with the genetic profiles of patients for a functional diagnostic approach. NSCLC cultures responded differently to TKIs, with erlotinib showing good efficacy regardless of mutation burden or EGFR status. However, the modulation of MDR mechanisms by erlotinib, such as increased ABCG2 expression, highlights the challenges associated with erlotinib treatment. Other TKIs showed limited efficacy, highlighting the variability of response in NSCLC. Genetic alterations in signaling pathways associated with drug resistance and sensitivity, including TP53 mutations, likely contributed to the variable responses to TKIs. The relationships between ABC transporter expression, gene alterations, and response to TKIs did not show consistent patterns. Our results suggest that in addition to mutational status, performing functional sensitivity screening is critical for identifying appropriate treatment strategies with TKIs. These results underscore the importance of considering drug sensitivity, off-target effects, MDR risks, and patient-specific genetic profiles when optimizing NSCLC treatment and highlight the potential for personalized approaches, especially in early stages. Full article

Multidrug resistance (MDR) commonly leads to cancer treatment failure because cancer cells often expel chemotherapeutic drugs using ATP-binding cassette (ABC) transporters, which reduce drug levels within the cells. This study investigated the clinical characteristics and single nucleotide variant (SNV) in ABCB1, ABCC1, ABCC2, ABCC4, and ABCG2, and their association with mortality in pediatric patients with central nervous system tumors (CNST). Using TaqMan probes, a real-time polymerase chain reaction genotyped 15 SNPs in 111 samples. Patients were followed up until death or the last follow-up day using the Cox proportional hazards model. An association was found between the rs1045642 (ABCB1) in the recessive model (HR = 2.433, 95% CI 1.098–5.392, p = 0.029), and the ICE scheme in the codominant model (HR = 9.810, 95% CI 2.74–35.06, p ≤ 0.001), dominant model (HR = 6.807, 95% CI 2.87–16.103, p ≤ 0.001), and recessive model (HR = 6.903, 95% CI 2.915–16.544, p = 0.038) significantly increased mortality in this cohort of patients. An association was also observed between the variant rs3114020 (ABCG2) and mortality in the codominant model (HR = 5.35, 95% CI 1.83–15.39, p = 0.002) and the dominant model (HR = 4.421, 95% CI 1.747–11.185, p = 0.002). A significant association between the ICE treatment schedule and increased mortality risk in the codominant model (HR = 6.351, 95% CI 1.831–22.02, p = 0.004, HR = 9.571, 95% CI 2.856–32.07, p ≤ 0.001), dominant model (HR = 6.592, 95% CI 2.669–16.280, p ≤ 0.001), and recessive model (HR = 5.798, 95% CI 2.411–13.940, p ≤ 0.001). The genetic variants rs3114020 in the ABCG2 gene and rs1045642 in the ABCB1 gene and the ICE chemotherapy schedule were associated with an increased mortality risk in this cohort of pediatric patients with CNST. Full article

The aim of this study was to establish the relationship between different polymorphisms in drug transporter and metabolizer genes and resistance to imatinib in chronic myeloid leukemia (CML). For this purpose, an exhaustive search was carried out in the Scopus, Web of Science, and PubMed databases using different combinations of keywords with different inclusion and exclusion criteria. The meta-analysis included nine studies that met the established criteria. The results of the study showed that the polymorphic variants AG and GG of CYP3A5*3 are associated with response to treatment, presenting a significantly lower risk with resistance to imatinib. Likewise, the variants T1236C and G2677T/A of the ABCB1 gene show a significant association with treatment efficacy. In addition, the genetic polymorphism 1236T, homozygous CC of the MDR1 gene, significantly influences the increased risk of cytogenetic relapse and the polymorphic variant 361G>A GA of the SLCO1A2 gene significantly affects the complete molecular response. Full article

Genetic polymorphisms in ATP-binding cassette subfamily B member 1 (ABCB1, also known as MDR1) have been reported to be possibly associated with the regulation of response to antiseizure medications. The aim of this study was to investigate the association of ABCB1 polymorphisms with the efficacy of and adverse drug reactions to valproic acid among Chinese children with epilepsy. A total of 170 children from southern China with epilepsy treated with valproic acid for more than one year were recruited, including 61 patients with persistent seizures and 109 patients who were seizure-free. Two single nucleotide polymorphisms of ABCB1, rs1128503 and rs3789243, were genotyped using the Sequenom MassArray system. The two single nucleotide polymorphisms of ABCB1 were found to be significantly associated with treatment outcomes of valproic acid in children with epilepsy. Carriers with the TT genotype of ABCB1 rs1128503 were more inclined to exhibit persistent seizures after treatment with valproic acid (p = 0.013). The CC genotype of rs3789243 was observed to be a potential protective factor for valproic acid-induced gastrointestinal adverse drug reactions (p = 0.018), but possibly increased the risk of valproic acid-induced cutaneous adverse drug reactions (p = 0.011). In contrast, the CT genotype of rs3789243 was associated with a lower risk of valproic acid-induced cutaneous adverse drug reactions (p = 0.011). Haplotype analysis showed that CC haplotype carriers tended to respond better to valproic acid treatment (p = 0.009). Additionally, no significant association was found between ABCB1 polymorphisms and serum concentrations of valproic acid. This study revealed that the polymorphisms and haplotypes of the ABCB1 gene might be associated with the treatment outcomes of valproic acid in Chinese children with epilepsy. Full article

ABCB1, also known as MDR1, is a gene that encodes P-glycoprotein (P-gp), a membrane-associated ATP-dependent transporter. P-gp is widely expressed in many healthy tissues—in the gastrointestinal tract, liver, kidney, and at the blood–brain barrier. P-gp works to pump xenobiotics such as toxins and drugs out of cells. P-gp is also commonly upregulated across multiple cancer types such as ovarian, breast, and lung. Overexpression of ABCB1 has been linked to the development of chemotherapy resistance across these cancers. In vitro work across a wide range of drug-sensitive and -resistant cancer cell lines has shown that upon treatment with chemotherapeutic agents such as doxorubicin, cisplatin, and paclitaxel, ABCB1 is upregulated. This upregulation is caused in part by a variety of genetic and epigenetic mechanisms. This includes single-nucleotide variants that lead to enhanced P-gp ATPase activity without increasing ABCB1 RNA and protein levels. In this review, we summarize current knowledge of genetic and epigenetic mechanisms leading to ABCB1 upregulation and P-gp-enhanced ATPase activity in the setting of chemotherapy resistance across a variety of cancers. Full article

P-glycoprotein (P-gp) has been implicated in lung cancer development, disease progression, and patient survival. Changes in the ABCB1 expression level may correlate with tumorigenesis and the formation of multidrug resistance (MDR). In addition, epigenetic modifications such as DNA methylation are involved in the regulation of the transcriptional activity of this gene. Therefore, we focused on an analysis of changes in the expression of ABCB1 and its methylation, taking into account their potential associations with the clinicopathological parameters of LUAD and LUSC. The TNMplot, UALCAN, cBioPortal, PrognoScan, and MEXPRESS databases were used to investigate the role of this gene in lung cancer progression. ABCB1 expression in lung tissue was significantly downregulated in cancer cells, but differences also resulted from age, gender, ethnicity, and smoking cessation. Moreover, decreased levels of gene transcript were associated with both a higher stage of cancer and a lower probability of survival. It is worth emphasizing that the presence/direction of ABCB1 expression changes are frequently unique to specific histological tumor subtypes. Finally, it is equally important that the main methylation promoter is one of the causes of decreased gene expression in lung cancer cells. Taken together, these data establish the ABCB1 transporter gene as an important prognostic factor that could alter disease progression and contribute to the survival of cancer patients. Full article