Sunitinib induced resistance of endothelial cells by up-regulating P-glycoprotein and PI3K/Akt pathway

Abstract Drug resistance is a crucial obstacle to achieve satisfactory chemotherapeutic effects. Numerous studies have shown that the PI3K/Akt signaling pathway plays a significant role in various processes of cellular events and tumor progression, while few studies have focused on the PI3K/Akt signaling pathway in drug resistance of endothelial cells. The present study aims to explore the relationship of PI3K/Akt signaling and cellular resistance to anticancer drugs in human microvessel endothelial cells (HMEC-1). We established stable sunitinib-resiatant human microvessel endothelial cells (HMEC-su) after long-term exposure to sunitinib (a small-molecule tyrosine kinase receptor inhibitor) for 12 months. HMEC-su showed significant alternations of cell morphology and exhibited a 2.32-fold higher IC50 of sunitinib than parental HMEC-1 cells. Expression of P-glycoprotein (P-gp) and breast cancer-resistance protein (ABCG2) which mediates drug efflux, increased significantly in HMEC-su lines compared with HMEC-1 cells by western blots assay. Our study further demonstrates that LY294002 (blocking the PI3K/Akt pathway) enhances the sensibility of HMEC-su to suntinib and inhibits the gene transcription and protein expression of P-gp, ABCG2 in HMEC-su cells. In conclusion, these results indicate that LY294002 could reverse P-gp and ABCG2 mediated-drug resistance to sunitinib in HMEC-su cells by inhibiting PI3K/Akt signaling.

Estudo da permeabilidade de fármacos por meio do modelo de saco intestinal de ratos / Study of drug permeability through the rat gut sac model

Os parâmetros de permeabilidade e solubilidade são fundamentais à absorção oral de fármacos e a partir dessas características, foi criado o Sistema de Classificação Biofarmacêutica, através do qual os fármacos são divididos em quatro classes. Atualmente, para a determinação da solubilidade de um fármaco, existem diversos métodos padronizados por agências regulatórias, no entanto, para a determinação da permeabilidade, os ensaios são passíveis de diversas variações em sua execução, diminuindo a confiabilidade dos resultados obtidos e impossibilitando a comparação dos mesmos quando realizados com técnicas diferentes umas das outras. O objetivo do presente trabalho é avaliar as variáveis experimentais do modelo do saco intestinal que podem influenciar nos resultados de permeabilidade aparente de fármacos e na viabilidade do tecido. O presente estudo foi aprovado pelo Comitê de Ética no Uso de Animais da FCF-USP (109.2018-P574). Foram utilizados 33 Rattus norvegicus da linhagem Wistar, machos, jovens adultos, com peso entre 200 g e 300 g. Para realização do procedimento, cada animal permaneceu em jejum por cerca de quatro horas e após adequada anestesia a porção do jejuno do intestino delgado foi retirada e dividida em seis segmentos de aproximadamente 8,5cm cada. Foram realizados experimentos com e sem inversão do saco intestinal, submetidos a diferentes tempos de banho de gelo após sua ressecção, na presença ou ausência de inibidor da glicoproteína-P (verapamil). Os fármacos naproxeno e famotidina foram empregados como marcadores de alta e baixa permeabilidade, respectivamente. A losartana foi utilizada como substrato da glicoproteína P. Cada um dos sacos intestinais foi colocado em um tubo de ensaio contendo tampão Krebs, a 37°C, saturado com gás carbogênio. Para avaliação da integridade e viabilidade dos segmentos intestinais, observou-se a presença de movimentos peristálticos e coletaram-se amostras do meio de incubação nos tempos 0, 30, 45, 60, 90 e 120 minutos para quantificação dos fármacos e de glicose, uma vez que esta é ativamente transportada para a serosa do intestino delgado. Determinou-se a permeabilidade aparente de cada fármaco e as concentrações de glicose nas diferentes condições experimentais, realizou-se planejamento fatorial multinível e os resultados foram analisados por análise variância (ANOVA), seguida de pós-teste de Tukey. Observou-se que as variáveis experimentais interferiram de forma significativa na viabilidade tecidual e na permeabilidade aparente dos fármacos. Não foram observadas diferenças significativas da permeabilidade de fármacos nos diferentes segmentos do jejuno. A glicose mostrou-se um bom marcador de viabilidade tecidual e foi constatado que a presença ou ausência de movimentos peristálticos não está relacionada diretamente com a viabilidade do tecido. Uma vez que foram constatadas tantas interferências nos resultados, é imprescindível que os procedimentos experimentais sejam padronizados, para que os resultados apresentem menor variabilidade e possam ser comparados entre si

The permeability and solubility parameters are fundamental to the oral absorption of drugs and from these characteristics, the Biopharmaceutical Classification System was created, through which drugs are divided into four classes. Currently, for the determination of the solubility of a drug, there are several methods standardized by regulatory agencies, however, for the determination of permeability, the tests are subject to several variations in their execution, reducing the reliability of the results obtained and making it impossible to compare the results obtained. same when performed with different techniques. The aim of this study is to evaluate if different experimental conditions can influence the results of apparent drug permeability and tissue viability on gut sac model. The present study was approved by the Ethics Committee for the Use of Animals of FCF-USP (109.2018-P574). Thirty-three male, young adult Rattus norvegicus were used, weighing between 200 g and 300 g. To perform the procedure, each animal fasted for about four hours and after adequate anesthesia, the portion of the jejunum of the small intestine was removed and divided into six segments of approximately 8.5 cm each. Experiments were performed with and without inversion of the gut sac, submitted to different times of ice bath after its resection, in the presence or absence of a P-glycoprotein inhibitor (verapamil). The drugs naproxen and famotidine were used as markers of high and low permeability, respectively. Losartan was used as a substrate for P-glycoprotein. Each of the gut sacs was placed in a test tube containing Krebs buffer, at 37°C, saturated with carbogen gas. To evaluate the integrity and viability of the intestinal segments, the presence of peristaltic movements was observed and samples of the incubation medium were collected at 0, 30, 45, 60, 90 and 120 minutes for quantification of drugs and glucose, as it is actively transported to the serosa of the small intestine. The apparent permeability of each drug and the glucose concentrations were determined under different experimental conditions, multilevel factorial design was performed and the results were analyzed by analysis of variance (ANOVA), followed by Tukey's post-test. It was observed that the experimental variables significantly interfered in the tissue viability and in the apparent permeability of the drugs. No significant differences in drug permeability were observed in the different segments of the jejunum. Glucose proved to be a good marker of tissue viability and it was found that the presence or absence of peristaltic movements is not directly related to tissue viability. Since so many interferences were found in the results, it is essential that the experimental procedures be standardized, so that the results show less variability and can be compared between different authors

Genetic and pharmacological relationship between P-glycoprotein and increased cardiovascular risk associated with clarithromycin prescription: An epidemiological and genomic population-based cohort study in Scotland, UK.

BACKGROUND: There are conflicting reports regarding the association of the macrolide antibiotic clarithromycin with cardiovascular (CV) events. A possible explanation may be that this risk is partly mediated through drug-drug interactions and only evident in at-risk populations. To the best of our knowledge, no studies have examined whether this association might be mediated via P-glycoprotein (P-gp), a major pathway for clarithromycin metabolism. The aim of this study was to examine CV risk following prescription of clarithromycin versus amoxicillin and in particular, the association with P-gp, a major pathway for clarithromycin metabolism. METHODS AND FINDINGS: We conducted an observational cohort study of patients prescribed clarithromycin or amoxicillin in the community in Tayside, Scotland (population approximately 400,000) between 1 January 2004 and 31 December 2014 and a genomic observational cohort study evaluating genotyped patients from the Genetics of Diabetes Audit and Research Tayside Scotland (GoDARTS) study, a longitudinal cohort study of 18,306 individuals with and without type 2 diabetes recruited between 1 December 1988 and 31 December 2015. Two single-nucleotide polymorphisms associated with P-gp activity were evaluated (rs1045642 and rs1128503 -AA genotype associated with lowest P-gp activity). The primary outcome for both analyses was CV hospitalization following prescription of clarithromycin versus amoxicillin at 0-14 days, 15-30 days, and 30 days to 1 year. In the observational cohort study, we calculated hazard ratios (HRs) adjusted for likelihood of receiving clarithromycin using inverse proportion of treatment weighting as a covariate, whereas in the pharmacogenomic study, HRs were adjusted for age, sex, history of myocardial infarction, and history of chronic obstructive pulmonary disease. The observational cohort study included 48,026 individuals with 205,227 discrete antibiotic prescribing episodes (34,074 clarithromycin, mean age 73 years, 42% male; 171,153 amoxicillin, mean age 74 years, 45% male). Clarithromycin use was significantly associated with increased risk of CV hospitalization compared with amoxicillin at both 0-14 days (HR 1.31; 95% CI 1.17-1.46, p < 0.001) and 30 days to 1 year (HR 1.13; 95% CI 1.06-1.19, p < 0.001), with the association at 0-14 days modified by use of P-gp inhibitors or substrates (interaction p-value: 0.029). In the pharmacogenomic study (13,544 individuals with 44,618 discrete prescribing episodes [37,497 amoxicillin, mean age 63 years, 56% male; 7,121 clarithromycin, mean age 66 years, 47% male]), when prescribed clarithromycin, individuals with genetically determined lower P-gp activity had a significantly increased risk of CV hospitalization at 30 days to 1 year compared with heterozygotes or those homozygous for the non-P-gp-lowering allele (rs1045642 AA: HR 1.39, 95% CI 1.20-1.60, p < 0.001, GG/GA: HR 0.99, 95% CI 0.89-1.10, p = 0.85, interaction p-value < 0.001 and rs1128503 AA 1.41, 95% CI 1.18-1.70, p < 0.001, GG/GA: HR 1.04, 95% CI 0.95-1.14, p = 0.43, interaction p-value < 0.001). The main limitation of our study is its observational nature, meaning that we are unable to definitively determine causality. CONCLUSIONS: In this study, we observed that the increased risk of CV events with clarithromycin compared with amoxicillin was associated with an interaction with P-glycoprotein.

Population Pharmacokinetics of Edoxaban in Patients with Non-Valvular Atrial Fibrillation in the ENGAGE AF-TIMI 48 Study, a Phase III Clinical Trial.

INTRODUCTION: Edoxaban is a novel factor Xa inhibitor. This study characterizes the population pharmacokinetics of edoxaban in patients with non-valvular atrial fibrillation (NVAF) included in the phase III ENGAGE AF-TIMI 48 study, evaluates covariates for the dose-exposure relationship in this population, and assesses the impact of protocol-specified dose reductions on exposure using simulations. METHODS: Model development was performed using NONMEM(®) and based on sparse data from the ENGAGE AF-TIMI 48 study augmented with dense data from 13 phase I studies to inform and stabilize the model. The influence of body weight (WT), creatinine clearance (CLCR), concomitant P-glycoprotein (P-gp) inhibitors, age, sex, race, and NVAF on pharmacokinetic parameters was evaluated based on statistical significance and clinical relevance. RESULTS: A two-compartment model with first-order elimination and first-order absorption after an absorption lag-time best described the data. Apparent volume and clearance terms increased with increasing WT. Apparent renal clearance increased with increasing CLCR. Apparent non-renal, renal, and inter-compartmental clearance terms differed between phase I volunteers and NVAF patients. Asian patients were found to have increased apparent central volume of distribution, bioavailability, and total apparent clearance. Concomitant P-gp inhibitors increased the bioavailability statistically significantly, but this did not reach clinical relevance. CONCLUSION: Edoxaban disposition and the variability in this disposition, including influence of covariates, after oral administration were adequately characterized in patients with NVAF. The 50 % dose reduction in patients with low WT (≤60 kg), moderate renal impairment (CLCR ≤50 mL/min), or concomitant P-gp inhibitors led to 30 % lower exposure than in the other patients.

Overview of P-glycoprotein inhibitors: a rational outlook

P-glycoprotein (P-gp), a transmembrane permeability glycoprotein, is a member of ATP binding cassette (ABC) super family that functions specifically as a carrier mediated primary active efflux transporter. It is widely distributed throughout the body and has a diverse range of substrates. Several vital therapeutic agents are substrates to P-gp and their bioavailability is lowered or a resistance is induced because of the protein efflux. Hence P-gp inhibitors were explored for overcoming multidrug resistance and poor bioavailability problems of the therapeutic P-gp substrates. The sensitivity of drug moieties to P-gp and vice versa can be established by various experimental models in silico, in vitro and in vivo. Ever since the discovery of P-gp, the research plethora identified several chemical structures as P-gp inhibitors. The aim of this review was to emphasize on the discovery and development of newer, inert, non-toxic, and more efficient, specifically targeting P-gp inhibitors, like those among the natural herb extracts, pharmaceutical excipients and formulations, and other rational drug moieties. The applications of cellular and molecular biology knowledge, in silico designed structural databases, molecular modeling studies and quantitative structure-activity relationship (QSAR) analyses in the development of novel rational P-gp inhibitors have also been mentioned.

Glicoproteína-p (P-gp), uma glicoproteína de transmembrana permeável, é um membro da superfamília (ABC) de cassete de gene de ligação de ATP que funciona especificamente como um carreador mediado pelo transportador de efluxo ativo primário. É amplamente distribuído por todo o corpo e apresenta uma gama diversificada de substratos. Diversos agentes terapêuticos vitais são substratos para P-gp e sua biodisponibilidade é reduzida ou a resistência é induzida devido ao efluxo de proteínas. Portanto, os inibidores da P-gp foram explorados para a superação da resistência a múltiplas drogas e problemas de biodisponibilidade deficiente dos substratos terapêuticos da P-gp. A sensibilidade das moléculas da droga à P-gp e vice-versa, pode ser estabelecida por vários modelos experimentais in silico, in vitro e in vivo. Desde a descoberta da P-gp, diversas pesquisas identificaram várias estruturas químicas como inibidores da P-gp. O objetivo deste presente estudo foi o de enfatizar a descoberta e desenvolvimento de inibidores mais novos, inertes, atóxicos e mais eficazes, visando especificamente os da P-gp, como aqueles entre os extratos vegetais, excipientes e formulações farmacêuticas, e outras moléculas racionais de droga. As aplicações do conhecimento de biologia celular e molecular, bancos de dados estruturais in silico, estudos de modelagem molecular e análises da relação quantitativa estrutura-atividade (QSAR) no desenvolvimento de novos inibidores racionais da P-gp também foram mencionados.

Reversal of multidrug resistance by 4-chloro-N-(3-((E)-3-(4-hydroxy-3-methoxyphenyl)acryloyl)phenyl)benzamide through the reversible inhibition of P-glycoprotein.

Overexpression of P-glycoprotein (P-gp) is one of the major obstacles to successful cancer chemotherapy. In this study, we examined the ability of 4-chloro-N-(3-((E)-3-(4-hydroxy-3-methoxyphenyl)acryloyl)phenyl)benzamide (C-4) to reverse multidrug resistance (MDR) in P-gp expressing KBV20C cells. Treatment of KBV20C cells with C-4 led to a dramatic increase in paclitaxel- or vincristine-induced cytotoxicity without any cytotoxicity by itself. In parallel, C-4 treatment caused an increase in apoptotic cell death by paclitaxel or vincristine. Furthermore, C-4 treatment significantly increases in intracellular accumulation of fluorescent P-gp substrate rhodamine 123, indicating that C-4 treatment leads to reversal of the MDR phenotype resulting from an increased accumulation of anticancer drugs by inhibiting drug efflux function of P-gp. This notion is further supported by the observation that C-4 treatment potentiates paclitaxel-induced G(2)/M arrest of the cell cycle. In addition, the drug efflux function of P-gp was reversibly inhibited by C-4 treatment, while the expression level of P-gp was not affected. Collectively, our results describe the potential of C-4 to reverse the P-gp-mediated MDR phenotype through reversible inhibition of P-gp function, which may make it an attractive new agent for the chemosensitization of cancer cells.

A importância da glicoproteína P (P-gp) e dos polipeptídios transportadores de ânions orgânicos (OATP) nas interaçöes medicamentosas / The importance of P-glyciprotein (P-gp) and organic anion-transpoting polypeptides (OATP) in drug interactions

As interaçöes medicamentosas que causam alteraçöes no metabolismo e biodisponibilidade das drogas têm sido parcialmente explicadas pelas atividades que estas drogas exercem sobre as isoenzimas do sistema citocromo P450 (CYP). Alguns estudos recentes, poréem, sugerem que novos sistemas transportadores ded droga chamados glicoproteína P (P-gp,P-glycoprotein) e polipeptidio transportador de ânions orgânicos (OATP, organic anion transporting polypeptide) porem causar o efluxo e influxo celular de várias classes de medicamentos. Estes mecanismos podem contribuir para as interaçöes medicamentosas por mecanismos independentes do metabolismo oxidativo via CYP. Alguns modelos experimentais criados para avaliar a funçäo da P-gp ou OATP demonstraram que pode haver alteraçöes desses transportadores com efeito significativo sobre a biodisponibilidade de rogas. Assim, a interferência sobre estes sistemas de transporte P-gp e OATP surge como um novo mecanismo potencialmente relacionado a interaçöes medicamentosas ae alimentares.au