An accurate haplotyping method using multiplex pyrosequencing with AS-PCR to detect ABCB1 haplotypes associated with rivaroxaban-derived hemorrhagic events.

In clinical practice, owing to the comprehensive genetic insights they offer, haplotypes have attracted greater attention than individual single nucleotide polymorphisms (SNPs). Due to the long distances across SNP locations, detecting the haplotype using genomic DNA is challenging. Current haplotyping methods are either expensive and labor-intensive (high-throughput DNA sequencing), or haplotyping a single clinical sample (computational approach) is impossible. Herein, we propose using mRNA as a haplotyping target to minimize the distance among SNPs and employing allele-specific PCR (AS-PCR) to pick up a desired haplotype, followed by multiplex pyrosequencing to type the alleles at the SNP location of interest. AS-PCR was improved by combining an additional 3'-phosphorylated modified probe to achieve the specific separation of two closely similar templates. Only the sample with more than two heterozygotes needs to be haplotyped; therefore, we propose a stratification strategy to screen the samples for further haplotyping. This method was evaluated by associating ABCB1 haplotypes with the rivaroxaban-derived side effect in a cohort of 505 patients with nephrotic syndrome, focusing on the SNPs of ABCB1: rs1236C > T, rs2677G > T/A, and rs3435C > T. We successfully identified five bleeding-related haplotypes: rs1236T-rs2677T-rs3435T, rs1236C-rs2677G-rs3435T, rs1236T-rs2677G-rs3435C, rs1236C-rs2677G-rs3435C, and rs1236T-rs2677T-rs3435C. We compared the results with those from the conventional computational algorithm PHASE and observed that PHASE results dismissed the impact of rs1236C-rs2677G-rs3435C and rs1236C-rs2677G-rs3435T on bleeding risk and erroneously suggested a false positive association of rs1236C-rs2677A-rs3435T with increased bleeding risk.

Oral N-acetylcysteine ameliorates liver fibrosis and enhances regenerative responses in Mdr2 knockout mice.

Cholangiopathies are poorly understood disorders with no effective therapy. The extrahepatic biliary tree phenotype is less studied compared to the intrahepatic biliary injury in both human disease and Mdr2-/- mice, the established cholestatic mouse model. This study aimed to characterize the extra hepatic biliary tree of Mdr2-/- mice at various ages and to determine if injury can be repaired with the antioxidant and glutathione precursor N-acetyl-L-Cysteine treatment (NAC). We characterized extra hepatic bile ducts (EHBD)s at various ages from 2 to 40 weeks old FVB/N and Mdr2-/- mice. We examined the therapeutic potential of local NAC ex vivo using EHBD explants at early and late stages of injury; and systematic therapy by in vivo oral administration for 3 weeks. EHBD and liver sections were assessed by histology and immunofluorescent stains. Serum liver enzyme activities were analyzed, and liver spatial protein expression analysis was performed. Mdr2-/- mice developed progressive EHBD injury, similar to extrahepatic PSC. NAC treatment of ex vivo EHBD explants led to improved duct morphology. In vivo, oral administration of NAC improved liver fibrosis, and decreased liver enzyme activities. Spatial protein analysis revealed cell-type specific differential response to NAC, collectively indicating a transition from pro-apoptotic into proliferative state. NAC treatment should be further investigated as a potential therapeutic option for human cholangiopathies.

Bleeding Events Associated with Rivaroxaban Therapy in Naive Patients with Nonvalvular Atrial Fibrillation: A Longitudinal Study from a Genetic Perspective with INR Follow-Up.

Background and Objectives: Rivaroxaban is a direct-acting anticoagulant used to prevent stroke in patients with atrial fibrillation. Rivaroxaban is a substrate for P-glycoprotein, which is encoded by the ABCB1 gene. Rivaroxaban is also metabolized by the CYP3A5 gene. Therefore, the current study is carried out to study the effects of polymorphisms in the ABCB1 and CYP3A5 genes, which may affect the plasma levels of rivaroxaban, with subsequent clinical outcomes (bleeding events) associated with the therapy. Materials and Methods: The study was conducted on 66 naive patients with atrial fibrillation treated with rivaroxaban. Blood samples of rivaroxaban were taken at 3 h and after 1 month following the administration of the drug to measure plasma levels. The blood level of rivaroxaban was measured with an HPLC-UV detector. Sanger sequencing was used to find polymorphisms in the targeted genes. Coagulation parameters were measured at 3 h and after 1 month of administration of rivaroxaban. Frequencies of bleeding events were recorded throughout the one-month course of drug therapy. Results: The heterozygous and homozygous mutant genotypes of ABCB1 (rs2032582, rs1045642, rs1128503, and rs4148738) and CYP3A5 (rs776746) showed lower plasma concentrations as compared to the wild-type genotype. ABCB1 (rs2032582, rs1045642, rs1128503, and rs4148738) and CYP3A5 (rs776746) gene polymorphisms had a statistically significant impact on the plasma concentration of rivaroxaban among the heterozygous and homozygous mutant genotypes compared to the wild-type genotype. The heterozygous variant of ABCB1 and homozygous variant of CYP3A5 suffered more events of bleeding. Conclusions: It was concluded that ABCB1 (rs2032582, rs1045642, rs1128503, and rs4148738) and CYP3A5 (rs776746) gene polymorphisms had a significant impact on the plasma levels of rivaroxaban in patients treated for atrial fibrillation on day three as well as after one month of the therapy. The lowest plasma levels were observed in patients with a homozygous variant of ABCB1 (rs2032582, rs1045642, or rs4148738) along with the CYP3A5*1/*3 allele. The heterozygous variant of ABCB1 SNPs and homozygous variant of CYP3A5 SNPs suffered more events of bleeding.

Analysis of ABCB1 Gene Polymorphisms and Their Impact on Tacrolimus Blood Levels in Kidney Transplant Recipients.

Tacrolimus (Tc) is an immunosuppressant used in transplant patients, but its therapeutic range is narrow, making precise dosing essential. This study investigates the association of three single nucleotide polymorphisms (SNPs) (ABCB1 3435C>T, 1236C>T, 2677G>T/A) with Tc levels over time to gain better insights into their role in personalized medicine. We conducted the study over four distinct periods: 1-14 days, 15-30 days, 31-60 days, and beyond 60 days post-transplantation. The analysis included allele, genotype, haplotype, and diplotype frequencies of the three SNPs concerning Tc blood levels. Statistical significance was determined, and false discovery rate (PFDR) correction was applied where appropriate. Significant associations were found between the C (ABCB1 C1236T), A alleles (ABCB1 G2677T/A), the CAC haplotype and lower Tc levels. The CAC-TGT and TGT-TGT diplotypes significantly influence how patients metabolize the drug. The TGT haplotype and the AA genotype (ABCB1 G2677T/A) were associated with higher Tc levels, suggesting a long-term genetic influence. Genetic factors, specifically certain SNPs and diplotypes, significantly impact Tc blood levels, with their influence varying over time.

Synthesis and evaluation of novel tetrahydroisoquinoline-benzo[h]chromen-4-one conjugates as dual ABCB1/CYP1B1 inhibitors for overcoming MDR in cancer.

The emergence of multidrug resistance (MDR) in malignant tumors is one of the major threats encountered currently by many chemotherapeutic agents. Among the various mechanisms involved in drug resistance, P-glycoprotein (P-gp, ABCB1), a member of the ABC transporter family that significantly increases the efflux of various anticancer drugs from tumor cells, and the metabolic enzyme CYP1B1 are widely considered to be two critical targets for overcoming MDR. Unfortunately, no MDR modulator has been approved by the FDA to date. In this study, based on pharmacophore hybridization, bioisosteric and fragment-growing strategies, we designed and synthesized 11 novel tetrahydroisoquinoline-benzo[h]chromen-4-one conjugates as dual ABCB1/CYP1B1 inhibitors. Among them, the preferred compound A10 exhibited the best MDR reversal activity (IC50 = 0.25 µM, RF = 44.4) in SW620/AD300 cells, being comparable to one of the most potent third-generation P-gp inhibitors WK-X-34. In parallel, this dual ABCB1/CYP1B1 inhibitory effect drives compound A10 exhibiting prominent drug resistance reversal activity to doxorubicin (IC50 = 4.7 µM, RF = 13.7) in ABCB1/CYP1B1-overexpressing DOX-SW620/AD300-1B1 resistant cells, which is more potent than that of the CYP1B1 inhibitor ANF. Furthermore, although compound A2 possessed moderate ABCB1/CYP1B1 inhibitory activity, it showed considerable antiproliferative activity towards drug-resistant SW620/AD300 and MKN45-DDP-R cells, which may be partly related to the increase of PUMA expression to promote the apoptosis of the drug-resistant MKN45-DDP-R cells as confirmed by proteomics and western blot assay. These results indicated that the tetrahydroisoquinoline-benzo[h]chromen-4-one conjugates may provide a fundamental scaffold reference for further discovery of MDR reversal agents.

Clinical Value of ABCB1 and PAI-1 Gene Polymorphisms in Predicting Glucocorticoid-induced Adverse Reactions in Nephrotic Syndrome Patients.

OBJECTIVE: Glucocorticoid (GC)-induced adverse reactions (ARs) have been extensively studied due to their potential impact on patients' health. This study aimed to examine the potential correlation between two polymorphisms [adenosine triphosphate-binding cassette B1 (ABCB1) C3435T and plasminogen activator inhibitor-1 (PAI-1) 4G/5G] and various GC-induced ARs in nephrotic syndrome (NS) patients. METHODS: In this study, 513 NS patients who underwent GC treatment were enrolled. Then, the patients were divided into two groups based on ABCB1 C3435T and PAI-1 4G/5G genotyping, and intergroup comparisons of clinicopathological data and GC-induced ARs were performed. Univariate and multivariate logistic analyses were subsequently conducted to identify potential risk factors for GC-induced ARs, and a nomogram was subsequently established and validated via the area under the ROC curve (AUC), calibration curve and decision curve analysis (DCA). RESULTS: We identified ABCB1 C3435T as an independent risk factor for the development of steroid-associated avascular necrosis of the femoral head (SANFH) (OR: 2.191, 95% CI: 1.258-3.813, P=0.006) but not as a risk factor for the occurrence of steroid diabetes mellitus (S-DM). On the other hand, PAI-1 4G/5G was identified as an independent risk factor for the development of both SANFH (OR: 2.198, 95% CI: 1.267-3.812, P=0.005) and S-DM (OR: 2.080, 95% CI: 1.166-3.711, P=0.013). Notably, no significant correlation was found between the two gene polymorphisms and other GC-induced ARs. In addition, two nomograms were established and validated to demonstrate strong calibration capability and clinical utility. CONCLUSION: Assessing ABCB1 C3435T and PAI-1 4G/5G before steroid treatment in NS patients could be useful for identifying patients at a high risk of developing SANFH and S-DM.

Enteroids to Study Pediatric Intestinal Drug Transport.

Intestinal maturational changes after birth affect the pharmacokinetics (PK) of drugs, having major implications for drug safety and efficacy. However, little is known about ontogeny-related PK patterns in the intestine. To explore the accuracy of human enteroid monolayers for studying drug transport in the pediatric intestine, we compared the drug transporter functionality and expression in enteroid monolayers and tissue from pediatrics and adults. Enteroid monolayers were cultured of 14 pediatric [median (range) age: 44 weeks (2 days-13 years)] and 5 adult donors, in which bidirectional drug transport experiments were performed. In parallel, we performed similar experiments with tissue explants in Ussing chamber using 11 pediatric [median (range) age: 54 weeks (15 weeks-10 years)] and 6 adult tissues. Enalaprilat, propranolol, talinolol, and rosuvastatin were used to test paracellular, transcellular, and transporter-mediated efflux by P-gp and breast cancer resistance protein (BCRP), respectively. In addition, we compared the expression patterns of ADME-related genes in pediatric and adult enteroid monolayers with tissues using RNA sequencing. Efflux transport by P-gp and BCRP was comparable between the enteroids and tissue. Efflux ratios (ERs) of talinolol and rosuvastatin by P-gp and BCRP, respectively, were higher in enteroid monolayers compared to Ussing chamber, likely caused by experimental differences in model setup and cellular layers present. Explorative statistics on the correlation with age showed trends of increasing ER with age for P-gp in enteroid monolayers; however, it was not significant. In the Ussing chamber setup, lower enalaprilat and propranolol transport was observed with age. Importantly, the RNA sequencing pathway analysis revealed that age-related variation in drug metabolism between neonates and adults was present in both enteroids and intestinal tissue. Age-related differences between 0 and 6 months old and adults were observed in tissue as well as in enteroid monolayers, although to a lesser extent. This study provides the first data for the further development of pediatric enteroids as an in vitro model to study age-related variation in drug transport. Overall, drug transport in enteroids was in line with data obtained from ex vivo tissue (using chamber) experiments. Additionally, pathway analysis showed similar PK-related differences between neonates and adults in both tissue and enteroid monolayers. Given the challenge to elucidate the effect of developmental changes in the pediatric age range in human tissue, intestinal enteroids derived from pediatric patients could provide a versatile experimental platform to study pediatric phenotypes.

Systemic Codelivery of Thymoquinone and Doxorubicin by Targeted Mesoporous Silica Nanoparticle Sensitizes Doxorubicin-Resistant Breast Cancer by Interfering between the MDR1/P-gp and miR 298 Crosstalk.

Multi drug resistance (MDR) in breast carcinoma still poses a significant impairment to successful chemotherapy. As the arsenal of anticancer agents increases with improved preclinical methods, the growth of therapeutic drug combinations is now unprecedented. The malignancies addressed by mono drugs often fail to limit cancer progression, resulting in resistant cancer, thereby offering combinatorial therapies a terrific edge over monodrug regimes. However, the selection of drug combinations required enough preliminary evidence for their synergistic effect. The fundamental mechanisms of MDR to chemotherapeutics are associated with the overexpression of membrane efflux pumps, alternations in drug targets, and increased drug metabolism. Unfortunately, it is very difficult for drugs to overcome resistance produced on their own or by another different drug action. In this context, herein, we report a simple delivery system for coencapsulation and intracellular codelivery of dual-drug thymoquinone (TQ) and doxorubicin (DOX) to resensitize DOX-resistant MDA MB231 cell line (231 R). The 231 R cell line developed in our lab showed an enhanced expression of the ATP-binding cassette (ABC) transporters P-gp1/MDR-1 and a declined miR-298 expression. The present delivery system is based on amine-functionalized mesoporous silica nanoparticles (MSNs), in which the side chain amine functional group was used to react with the carbonyl group of TQ, which acts as a pro-drug system (TQ-MSN) to release TQ and DOX simultaneously. DOX was encapsulated later into the above TQ-MSN by a simple diffusion method. The drugs containing MSNs were further coated with a hyaluronic acid-conjugated PEG-PLGA polymer (HA@TQ-DOX-MSN). This simple nanostrategy interferes with the MDR-1/miR-298 cross-talk, thereby allowing a significant reduction in drug efflux from the cell and highlighting a promising nanotechnology-based combinatorial delivery approach in managing breast cancer chemoresistance.

Pharmacogenetic insights into ABCB1, ABCC2, CYP1A2, and CYP2B6 variants with epilepsy susceptibility among Egyptian Children: A retrospective case-control study.

BACKGROUND: Pediatric epilepsy is a complicated neuropsychiatric disorder that is characterized by recurrent seizures and unusual synchronized electrical activities within brain tissues. It has a substantial effect on the quality of life of children, thus understanding of the hereditary considerations influencing epilepsy susceptibility and the response to antiepileptic medications is crucial. This study focuses on assessing the correlation of the ABCB1, ABCC2, CYP1A2, and CYP2B6 genetic polymorphisms with the susceptibility to epileptic seizures and their contributions to antiepileptic medication throughout the course of the disease. METHODS: This study included 134 Egyptian epileptic children, comprising 67 drug-responsive and 67 drug-resistant patients, along with 124 healthy controls matching for age, gender, and geographical district. Genotyping of the rs2032582, rs717620, rs2273697, rs762551, and rs3745274 variants was performed using the PCR technique. Statistical analyses, including haplotype, multivariate, logistic regression, and bioinformatics approaches, were conducted to evaluate the associations within the disease. RESULTS: The ABCC2*rs717620 (T allele) revealed an increased risk of epilepsy compared to healthy controls (OR = 2.12, p-value < 0.001), with the rs717620 (C/T + T/T genotypes) showing significant differences between drug-responsive and drug-resistant patients (p-value < 0.05). Moreover, the ABCC2*rs2273697 (A allele) indicated a decreased risk of epileptic seizures compared to healthy controls (OR = 0.51, p-value = 0.033), with the rs2273697 (G/A + A/A genotypes) indicating a significant association with drug-resistant patients (OR = 0.21, p-value = 0.002). The rs717620*T/rs2273697*G haplotype was significantly correlated with an elevated risk of epileptic seizures within drug-responsive patients (OR = 2.26, p-value = 0.019). Additionally, the CYP1A2*rs762551 (A allele) represented a protective effect against epilepsy susceptibility (OR = 0.50, p-value < 0.001), with the rs762551 (G/A + A/A genotypes) disclosing a substantial association with a decreased risk of epileptic seizures among drug-resistant patients compared to drug-responsive patients (OR = 0.07, p-value < 0.001). Conversely, the ABCB1*rs2032582 (G allele) and the CYP2B6*rs3745274 (T allele) did not attain a significant difference with the epilepsy risk compared to healthy controls (p-value > 0.05). CONCLUSIONS: The findings of our study emphasize the importance of pharmacogenetic screening in epilepsy research, particularly regarding to drug-resistant patients. The ABCC2*rs717620 variant conferred a significant correlation with elevated risk of epileptic seizures, while the ABCC2*rs2273697 and CYP1A2*rs762551 variants confirmed their contributions as protective markers against epilepsy development. Conversely, the ABCB1*rs2032582 and CYP2B6*rs3745274 alleles were not considered as independent risk factors with the course of epilepsy disease.

[Relationship between clopidogrel resistance and genetic variability in Kawasaki disease children with coronary artery lesions].

Objective: To analyze the distribution of clopidogrel metabolism-related gene variability in Kawasaki disease (KD) children with coronary artery lesions (CAL) across different age groups and the impact of genetic variability on the efficacy of clopidogrel antiplatelet therapy. Methods: A retrospective cohort study was conducted. Clinical data were collected from 46 KD children with CAL who were hospitalized in the Cardiovascular Center of Children's Hospital of Fudan University between January 2021 and August 2022 and were treated with clopidogrel, including gender, age, body mass index, course of KD, CAL severity grade, and baseline platelet count. According to their age, the children were divided into ≥2-year-old group and <2-year-old group. Their platelet responsiveness was assessed by adenosine diphosphate-induced platelet inhibition rate (ADPi) calculated via thromboelastography, and children were categorized into high on-treatment platelet reactivity (HTPR) and normal on-treatment platelet reactivity (NTPR) groups. Genotypes of CYP2C19, PON1 and ABCB1 were detected. The t test, one-way analysis of variance and Chi-square test were used for intergroup comparison. Results: Among the 46 KD children with CAL, 34 were male and 12 were female; 37 were ≥2-year-old and 9 were <2-year-old; 25 cases were in the HTPR group and 21 cases were in the NTPR group, with 19 HTPR and 18 NTPR in the ≥2-year-old group, and 6 HTPR and 3 NTPR in the <2-year-old group. Genetic analysis showed that 92 alleles among the 46 children, with frequencies of CYP2C19*1, CYP2C19*2, CYP2C19*3, CYP2C19*17, PON1 192Q, PON1 192R, ABCB1 3435C, ABCB1 3435T at 59% (54/92), 32% (29/92), 9% (8/92), 1% (1/92), 36% (36/92), 64% (59/92), 63% (58/92) and 37% (34/92), respectively. Analysis of the impact of genotype on ADPi revealed that in children aged ≥2 years, those with CYP2C19*1/*3 genotype had significantly lower ADPi than those with CYP2C19*1/*1 genotype ((34±15)% vs. (61±29)%, t=2.18, P=0.036). There were also no significant difference in ADPi among children with PON1 192Q homozygous, PON1 192R heterozygote and PON1 192R homozygous genotypes ((40±22)% vs. (52±33)% vs. (65±27)%, F=2.17, P=0.130), or among those with ABCB1 3435C homozygous, ABCB1 3435T heterozygote and ABCB1 3435T homozygous genotypes ((55±34)% vs. (60±27)% vs. (49±24)%, F=0.33, P=0.719). In <2-year-old group, there were no significant differences in ADPi across CYP2C19*1/*1, CYP2C19*1/*2 and CYP2C19*2*2 genotypes ((40±20)% vs. (53±37)% vs. (34±16)%, F=0.37, P>0.05). There were no significant differences in ADPi across CYP2C19*1/*1 and CYP2C19*1/*3 genotypes ((44±27)% vs. (42±20)%, t=0.08, P>0.05). There were no significant differences in ADPi across PON1 192Q homozygous, PON1 192R heterozygote and PON1 192R homozygous genotypes (45% vs. (55±27)% vs. (24±5)%, F=1.83, P>0.05). There were no significant differences in ADPi across ABCB1 3435C homozygous, ABCB1 3435T heterozygote and ABCB1 3435T homozygous genotypes ((36±16)% vs. (50±35)% vs. 45%, F=0.29, P>0.05). The risk analysis of HTPR in different genotypes revealed that in children aged ≥2 years, carrying at least 1 or 2 loss-of-function alleles of CYP2C19 was a risk factor for HTPR (OR=4.69, 10.00, 95%CI 1.11-19.83, 0.84-119.32, P=0.033, 0.046, respectively), and PON1 192R homozygosity and carrying at least one PON1 192R allele were protective factors against HTPR (OR=0.08, 0.13, 95%CI 0.01-0.86, 0.01-1.19, P=0.019, 0.043, respectively). Conclusion: KD children aged ≥2 years carrying CYP2C19 loss-of-function alleles and PON1 192Q are more likely to develop HTPR.

A phase I drug-drug interaction study to assess the effect of futibatinib on P-gp and BCRP substrates and of P-gp inhibition on the pharmacokinetics of futibatinib.

Futibatinib, an inhibitor of fibroblast growth factor receptor 1-4, is approved for the treatment of patients with advanced cholangiocarcinoma with FGFR2 fusions/rearrangements. In this phase I drug-drug interaction study, the effects of futibatinib on P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrates, and of P-gp inhibition on futibatinib pharmacokinetics (PK) were investigated in healthy adults aged 18-55 years. In part 1, 20 participants received digoxin (P-gp substrate) and rosuvastatin (BCRP substrate). Following a ≥10-day washout, futibatinib was administered for 7 days, with digoxin and rosuvastatin coadministered on the third day. In part 2, 24 participants received futibatinib. Following a ≥3-day washout, quinidine (P-gp inhibitor) was administered for 4 days, with futibatinib coadministered on day 4. Blood samples were collected predose and for 24 (futibatinib), 72 (rosuvastatin), and 120 h (digoxin) postdose. Urine samples (digoxin) were collected predose and for 120 h postdose. PK parameters were compared between treatments using analysis of variance. Coadministration with futibatinib had no effect on the PK of digoxin and rosuvastatin, and coadministration with quinidine had minimal effects on the PK of futibatinib. Differences in Cmax and AUC with and without futibatinib and quinidine, respectively, were <20%. The most common treatment-emergent adverse events were diarrhea (80%) and increased blood phosphorous (75%) in part 1 and prolonged electrocardiogram QT interval (38%) in part 2. The data show that futibatinib has no clinically meaningful effects on the PK of P-gp or BCRP substrates and that the effect of P-gp inhibition on futibatinib PK is not clinically relevant.

Anti-Inflammatory and Anti-(Lymph)angiogenic Properties of an ABCB5+ Limbal Mesenchymal Stem Cell Population.

Corneal transparency and avascularity are essential for vision. The avascular cornea transitions into the vascularized conjunctiva at the limbus. Here, we explore a limbal stromal cell sub-population that expresses ABCB5 and has mesenchymal stem cell characteristics. Human primary corneal stromal cells were enriched for ABCB5 by using FACS sorting. ABCB5+ cells expressed the MSC markers CD90, CD73, and CD105. ABCB5+ but not ABCB5- cells from the same donor displayed evidence of pluripotency with a significantly higher colony-forming efficiency and the ability of trilineage differentiation (osteogenic, adipogenic, and chondrogenic). The ABCB5+ cell secretome demonstrated lower levels of the pro-inflammatory protein MIF (macrophage migration inhibitory factor) as well as of the pro-(lymph)angiogenic growth factors VEGFA and VEGFC, which correlated with reduced proliferation of Jurkat cells co-cultured with ABCB5+ cells and decreased proliferation of blood and lymphatic endothelial cells cultured in ABCB5+ cell-conditioned media. These data support the hypothesis that ABCB5+ limbal stromal cells are a putative MSC population with potential anti-inflammatory and anti-(lymph)angiogenic effects. The therapeutic modulation of ABCB5+ limbal stromal cells may prevent cornea neovascularization and inflammation and, if transplanted to other sites in the body, provide similar protective properties to other tissues.

Short Communication: Novel Di- and Triselenoesters as Effective Therapeutic Agents Inhibiting Multidrug Resistance Proteins in Breast Cancer Cells.

Breast cancer has the highest incidence rate among all malignancies worldwide. Its high mortality is mainly related to the occurrence of multidrug resistance, which significantly limits therapeutic options. In this regard, there is an urgent need to develop compounds that would overcome this phenomenon. There are few reports in the literature that selenium compounds can modulate the activity of P-glycoprotein (MDR1). Therefore, we performed in silico studies and evaluated the effects of the novel selenoesters EDAG-1 and EDAG-8 on BCRP, MDR1, and MRP1 resistance proteins in MCF-7 and MDA-MB-231 breast cancer cells. The cytometric analysis showed that the tested compounds (especially EDAG-8) are inhibitors of BCRP, MDR1, and MRP1 efflux pumps (more potent than the reference compounds-novobiocin, verapamil, and MK-571). An in silico study correlates with these results, suggesting that the compound with the lowest binding energy to these transporters (EDAG-8) has a more favorable spatial structure affecting its anticancer activity, making it a promising candidate in the development of a novel anticancer agent for future breast cancer therapy.

Proteomic Dynamics of Multidrug Resistance Mechanisms in Lucena 1 Cell Line.

The Lucena 1 cell line, derived from the human chronic myeloid leukemia cell line K562 under selective pressure of vincristine supplementation, exhibits multidrug resistance (MDR). This study aims to explore and elucidate the underlying mechanisms driving MDR in the Lucena 1 cell line. A proteomic analysis comparing K562 and Lucena 1 revealed qualitative differences, with a focus on the ATP-dependent efflux pump, Translocase ABCB1, a key contributor to drug resistance. Tubulin analysis identified two unique isoforms, Tubulin beta 8B and alpha chain-like 3, exclusive to Lucena 1, potentially influencing resistance mechanisms. Additionally, the association of Rap1A and Krit1 in cytoskeletal regulation and the presence of STAT1, linked to the urea cycle and tumor development, offered insights into Lucena 1's distinctive biology. The increased expression of carbonic anhydrase I suggested a role in pH regulation. The discovery of COP9, a tumor suppressor targeting p53, further highlighted the Lucena 1 complex molecular landscape. This study offers new insights into the MDR phenotype and its multifactorial consequences in cellular pathways. Thus, unraveling the mechanisms of MDR holds promise for innovating cancer models and antitumor targeted strategies, since inhibiting the P-glycoprotein (P-gp)/ABCB1 protein is not always an effective approach given the associated treatment toxicity.

Brain Exposure to the Macrocyclic ALK Inhibitor Zotizalkib is Restricted by ABCB1, and Its Plasma Disposition is Affected by Mouse Carboxylesterase 1c.

Zotizalkib (TPX-0131), a fourth-generation macrocyclic anaplastic lymphoma kinase (ALK) inhibitor, is designed to overcome resistance due to secondary ALK mutations in non-small cell lung cancer (NSCLC). We here evaluated the pharmacokinetic roles of the ABCB1 (P-gp/MDR1) and ABCG2 (BCRP) efflux transporters, OATP1 influx transporters and the metabolizing enzymes CES1 and CYP3A in plasma and tissue disposition of zotizalkib after oral administration in relevant mouse models. Zotizalkib was efficiently transported by hABCB1 in vitro. In vivo, a significant ∼9-fold higher brain-to-plasma ratio was observed in Abcb1a/b-/- and Abcb1a/b;Abcg2-/- compared to wild-type mice. No change in brain disposition was observed in Abcg2-/- mice, suggesting that mAbcb1a/b markedly restricts the brain accumulation of zotizalkib. ABCB1-mediated efflux of zotizalkib was completely inhibited by elacridar, a dual ABCB1/ABCG2 inhibitor, increasing brain exposure without any signs of acute CNS-related toxicities. In Oatp1a/b-/- mice, no marked changes in plasma exposure or tissue-to-plasma ratios were observed, indicating that zotizalkib is not a substantial in vivo substrate for mOatp1a/b. Zotizalkib may further be metabolized by CYP3A4 but only noticeably at low plasma concentrations. In Ces1-/- mice, a 2.5-fold lower plasma exposure was seen compared to wild-type, without alterations in tissue distribution. This suggests increased plasma retention of zotizalkib by binding to the abundant mouse plasma Ces1c. Notably, the hepatic expression of human CES1 did not affect zotizalkib plasma exposure or tissue distribution. The obtained pharmacokinetic insights may be useful for the further development and optimization of therapeutic efficacy and safety of zotizalkib and related compact macrocyclic ALK inhibitors.

Characterization of Chemoresistance in Pancreatic Cancer: A Look at MDR-1 Polymorphisms and Expression in Cancer Cells and Patients.

Pancreatic malignancy is the fourth cause of cancer-related death in Western countries and is predicted to become the second leading cause of cancer-related mortality by 2030. The standard therapies (FOLFIRINOX and gemcitabine with nab-paclitaxel) are not resolutive because this type of cancer is also characterized by a high chemoresistance, due in part to the activity of the ATP Binding Cassette (ABC) pumps accounting for the reduction in the intracellular concentration of the drugs. In this work, we analyze the occurrence of single-nucleotide polymorphisms (SNPs) in the MDR-1 gene, in different pancreatic cancer cell lines, and in tissues from pancreatic cancer patients by DNA sequencing, as well as the expression levels of MDR-1 mRNA and protein, by qRT-PCR and Western Blot analysis. We found that gemcitabine-resistant cells, in conjunction with homozygosis of analyzed SNPs, showed high MDR-1 basal levels with further increases after gemcitabine treatment. Nevertheless, we did not observe in the human PDAC samples a correlation between the level of MDR-1 mRNA and protein expression and SNPs. Preliminary, we conclude that in our small cohort, these SNPs cannot be used as molecular markers for predicting the levels of MDR-1 mRNA/protein levels and drug responses in patients with PDAC.

Sitagliptin synergizes 5-fluorouracil efficacy in colon cancer cells through MDR1-mediated flux impairment and down regulation of NFκB2 and p-AKT survival proteins.

5-fluorouracil (5-FU) is an inexpensive treatment for colon cancer; however, its efficacy is limited by chemoresistance. This study investigates the combination therapy approach of 5-FU with Sitagliptin (Sita), a diabetic drug with potential cancer-modulating effects. The combination was evaluated in vitro and in silico, focusing on the effects of Sita and 5-FU on colon cancer cells. The results showed that the addition of Sita significantly decreased the IC50 of 5-FU compared to 5-Fu monotherapy. The study also found that Sita and 5-FU interact synergistically, with a combination index below 1. Sita successfully lowered the 5-FU dosage reduction index, decreasing the expression of MDR1 mRNA and p-AKT and NFκB2 subunits p100/p52 protein. Molecular docking analyses confirmed Sita's antagonistic action on MDR1 and thymidylate synthase proteins. The study concludes that sitagliptin can target MDR1, increase apoptosis, and significantly reduce the expression of p-AKT and NFκB2 cell-survival proteins. These effects sensitize colon cancer cells to 5-FU. Repurposing sitagliptin may enhance the anticancer effects of 5-FU at lower dosages.

Precision Medicine in Childhood Cancer: The Influence of Genetic Polymorphisms on Vincristine-Induced Peripheral Neuropathy.

Cancer is the leading cause of disease-related death among children. Vincristine (VCR), a key component of childhood cancer treatment protocols, is associated with the risk of peripheral neuropathy (PN), a condition that may be reversible upon drug discontinuation but can also leave lasting sequelae. Single nucleotide polymorphism (SNP) in genes involved in VCR pharmacokinetics and pharmacodynamics have been investigated in relation to an increased risk of PN. However, the results of these studies have been inconsistent. A retrospective cohort study was conducted to investigate the potential association of drug transporter genes from the ATP-binding cassette (ABC) family and the centrosomal protein 72 (CEP72) gene with the development of PN in 88 Caucasian children diagnosed with cancer and treated with VCR. Genotyping was performed using real-time PCR techniques for the following SNPs: ABCB1 rs1128503, ABCC1 rs246240, ABCC2 rs717620, and CEP72 rs924607. The results indicated that age at diagnosis (OR = 1.33; 95% CI = 1.07-1.75) and the ABCC1 rs246240 G allele (OR = 12.48; 95% CI = 2.26-100.42) were associated with vincristine-induced peripheral neuropathy (VIPN). No association was found between this toxicity and CEP72 rs924607. Our study provides insights that may contribute to optimizing childhood cancer therapy in the future by predicting the risk of VIPN.

ATP-binding cassette transporter inhibitor potency and substrate drug affinity are critical determinants of successful drug delivery enhancement to the brain.

BACKGROUND: Pharmacotherapy for brain diseases is severely compromised by the blood-brain barrier (BBB). ABCB1 and ABCG2 are drug transporters that restrict drug entry into the brain and their inhibition can be used as a strategy to boost drug delivery and pharmacotherapy for brain diseases. METHODS: We employed elacridar and tariquidar in mice to explore the conditions for effective inhibition at the BBB. Abcg2;Abcb1a/b knockout (KO), Abcb1a/b KO, Abcg2 KO and wild-type (WT) mice received a 3 h i.p. infusion of a cocktail of 8 typical substrate drugs in combination with elacridar or tariquidar at a range of doses. Abcg2;Abcb1a/b KO mice were used as the reference for complete inhibition, while single KO mice were used to assess the potency to inhibit the remaining transporter. Brain and plasma drug levels were measured by LC-MS/MS. RESULTS: Complete inhibition of ABCB1 at the BBB is achieved when the elacridar plasma level reaches 1200 nM, whereas tariquidar requires at least 4000 nM. Inhibition of ABCG2 is more difficult. Elacridar inhibits ABCG2-mediated efflux of weak but not strong ABCG2 substrates. Strikingly, tariquidar does not enhance the brain uptake of any ABCG2-subtrate drug. Similarly, elacridar, but not tariquidar, was able to inhibit its own brain efflux in ABCG2-proficient mice. The plasma protein binding of elacridar and tariquidar was very high but similar in mouse and human plasma, facilitating the translation of mouse data to humans. CONCLUSIONS: This work shows that elacridar is an effective pharmacokinetic-enhancer for the brain delivery of ABCB1 and weaker ABCG2 substrate drugs when a plasma concentration of 1200 nM is exceeded.

Inflammation alters the expression pattern of drug transporters during Caco-2 cell stimulation and azoxymethane-induced colon tumorigenesis.

Drug transporters play a pivotal role in modulating drug disposition and are subject to alterations under inflammatory conditions. This study aimed to elucidate the intricate expression patterns of drug transporters during both acute and chronic inflammation, which are closely linked to malignant transformation. To investigate acute inflammation, we employed an in vitro model by subjecting Caco-2 cells to various inflammatory stimuli (IL-1ß, TNF-α, or LPS) individually or in combination. The successful induction of inflammation was confirmed by robust increases in IL-6 and NO production. Notably, inflamed Caco-2 cells exhibited significantly diminished levels of ABCB1 and ABCG2, while the expression of ABCC2 was upregulated. For chronic inflammation induction in vivo, we employed the well-established AOM/DSS mouse model known for its association with colitis-driven tumorigenesis. Persistent inflammation was effectively monitored throughout the experiment via elevated IL-6 and NO levels. The sequential stages of tumorigenesis were confirmed through Ki-67 immunohistochemistry. Intriguingly, we observed gradual alterations in the expression patterns of the studied drug transporters during stepwise induction, with ABCB1, ABCG2, and ABCC1 showing downregulation and ABCC2 exhibiting upregulation. Immunohistochemistry further revealed dynamic changes in the expression of ABCB1 and ABCC2 during the induction cycles, closely paralleling the gradual increase in Ki-67 expression observed during the development of precancerous lesions. Collectively, our findings underscore the significant impact of inflammation on drug transporter expression, potentially influencing the process of malignant transformation of the colon.