RESUMO
Rutaecarpine (RUT), evodiamine (EOD), and dehydroevodiamine (DHED) are the three main bioactive indoloquinazoline alkaloids isolated from Euodia rutaecarpa, a widely prescribed traditional Chinese medicine. Here, the structure-activity relationships of these analogs for aryl hydrocarbon receptor (AHR) activation were explored by use of Ahr-deficient (Ahr-/-) mice, primary hepatocyte cultures, luciferase reporter gene assays, in silico ligand-docking studies, and metabolomics. In vitro, both mRNA analysis of AHR target genes in mouse primary hepatocytes and luciferase reporter assays in hepatocarcinoma cell lines demonstrated that RUT, EOD, and DHED significantly activated AHR, with an efficacy order of RUT > DHED > EOD. Ligand-docking analysis predicted that the methyl substitute at the N-14 atom was a key factor affecting AHR activation. In vivo, EOD was poorly orally absorbed and failed to activate AHR, whereas RUT and DHED markedly upregulated expression of the hepatic AHR gene battery in wild-type mice, but not in Ahr-/- mice. Furthermore, RUT, EOD, and DHED were not hepatotoxic at the doses used; however, RUT and DHED disrupted bile acid homeostasis in an AHR-dependent manner. These findings revealed that the methyl group at the N-14 atom of these analogs and their pharmacokinetic behaviors were the main determinants for AHR activation, and suggest that attention should be given to monitoring bile acid metabolism in the clinical use of E. rutaecarpa.
Assuntos
Ácidos e Sais Biliares/metabolismo , Medicamentos de Ervas Chinesas/farmacologia , Evodia/química , Homeostase/efeitos dos fármacos , Receptores de Hidrocarboneto Arílico/metabolismo , Alcaloides/farmacologia , Animais , Linhagem Celular Tumoral , Genes Reporter/efeitos dos fármacos , Células Hep G2 , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Alcaloides Indólicos/farmacologia , Fígado/diagnóstico por imagem , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Quinazolinas/farmacologia , RNA Mensageiro/metabolismo , Relação Estrutura-Atividade , Regulação para Cima/efeitos dos fármacosRESUMO
The objective of this study was to assess the underlying mechanisms of mango polyphenol decreased cell proliferation and tumor volume in ductal carcinoma in situ breast cancer. We hypothesized that mango polyphenols suppress signaling along the AKT/mTOR axis while up-regulating AMPK. To test this hypothesis, mango polyphenols (0.8 mg gallic acid equivalents per day) and pyrogallol (0.2 mg/day) were administered for 4 weeks to mice xenografted with MCF10DCIS.com cells subcutaneously (n=10 per group). Tumor volumes were significantly decreased, both mango and pyrogallol groups displayed greater than 50% decreased volume compared to control. There was a significant reduction of phosphorylated protein levels of IR, IRS1, IGF-1R, and mTOR by mango; while pyrogallol significantly reduced the phosphorylation levels of IR, IRS1, IGF-1R, p70S6K, and ERK. The protein levels of Sestrin2, which is involved in AMPK-signaling, were significantly elevated in both groups. Also, mango significantly elevated AMPK phosphorylation and pyrogallol significantly elevated LKB1 protein levels. In an in vitro model, mango and pyrogallol increased reactive oxygen species (ROS) generation and arrested cells in S phase. In silico modeling indicates that pyrogallol has the potential to bind directly to the allosteric binding site of AMPK, inducing activation. When AMPK expression was down-regulated using siRNA in vitro, pyrogallol reversed the reduced expression of AMPK. This indicates that pyrogallol not only activates AMPK, but also increases constitutive protein expression. These results suggest that mango polyphenols and their major microbial metabolite, pyrogallol, inhibit proliferation of breast cancer cells through ROS-dependent up-regulation of AMPK and down-regulation of the AKT/mTOR pathway.
Assuntos
Antineoplásicos Fitogênicos/uso terapêutico , Neoplasias da Mama/dietoterapia , Carcinoma Intraductal não Infiltrante/dietoterapia , Suplementos Nutricionais , Regulação Neoplásica da Expressão Gênica , Extratos Vegetais/uso terapêutico , Polifenóis/uso terapêutico , Proteínas Quinases Ativadas por AMP/antagonistas & inibidores , Proteínas Quinases Ativadas por AMP/química , Proteínas Quinases Ativadas por AMP/genética , Proteínas Quinases Ativadas por AMP/metabolismo , Animais , Antineoplásicos Fitogênicos/análise , Antineoplásicos Fitogênicos/química , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Carcinoma Intraductal não Infiltrante/metabolismo , Carcinoma Intraductal não Infiltrante/patologia , Linhagem Celular Tumoral , Proliferação de Células , Suplementos Nutricionais/análise , Feminino , Humanos , Mangifera , Camundongos Nus , Fosforilação , Extratos Vegetais/efeitos adversos , Extratos Vegetais/química , Polifenóis/efeitos adversos , Polifenóis/análise , Processamento de Proteína Pós-Traducional , Pirogalol/efeitos adversos , Pirogalol/análise , Pirogalol/uso terapêutico , Interferência de RNA , Espécies Reativas de Oxigênio/agonistas , Espécies Reativas de Oxigênio/metabolismo , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismo , Carga Tumoral , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Receptor tyrosine kinases (RTKs) play important roles in the control of fundamental cellular processes, influencing the balance between cell proliferation and death. RTKs have emerged as molecular targets for the treatment of various cancers. Green tea and its polyphenolic compounds, the catechins, exhibit chemopreventive and chemotherapeutic properties in many human cancer cell types, as well as in various carcinogenicity models in vivo. Epidemiological studies are somewhat less convincing, but some positive correlations have been observed. The tea catechins, including (-)-epigallocatechin-3-gallate (EGCG), have pleiotropic effects on cellular proteins and signaling pathways. This review focuses on the ability of the tea constituents to suppress RTK signaling, and summarizes the mechanisms by which EGCG and other catechins might exert their protective effects towards dysregulated RTKs in cancer cells. The findings are discussed in the context of ongoing clinical trials with RTK inhibitors, and the possibility for drug/nutrient interactions enhancing therapeutic efficacy.
Assuntos
Anticarcinógenos/farmacologia , Catequina/farmacologia , Receptores Proteína Tirosina Quinases/antagonistas & inibidores , Chá/metabolismo , Animais , Anticarcinógenos/uso terapêutico , Catequina/uso terapêutico , Humanos , Neoplasias/tratamento farmacológico , Receptores Proteína Tirosina Quinases/metabolismoRESUMO
Most cancer deaths result from spread of the primary tumor to distant sites (metastasis). MET is an important protein for metastasis in multiple tumor types. Here we report on the ability of tea catechins to suppress MET activation in human colon cancer cells and propose a mechanism by which they might compete for the kinase domain of the MET protein.
Assuntos
Antineoplásicos/farmacologia , Camellia sinensis , Catequina/farmacologia , Flavonoides/farmacologia , Modelos Moleculares , Fenóis/farmacologia , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Receptores de Fatores de Crescimento/antagonistas & inibidores , Antineoplásicos/química , Catequina/química , Linhagem Celular Tumoral , Neoplasias do Colo , Ensaios de Seleção de Medicamentos Antitumorais , Ácido Gálico/química , Humanos , Cinética , Polifenóis , Proteínas Proto-Oncogênicas/química , Proteínas Proto-Oncogênicas c-met , Receptores de Fatores de Crescimento/química , Relação Estrutura-AtividadeRESUMO
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor; the AhR Per-AhR/Arnt-Sim (PAS) domain binds ligands. We developed homology models of the AhR PAS domain to characterize previously observed intra- and interspecies differences in ligand binding using molecular docking. In silico structure-based virtual ligand screening using our model resulted in the identification of pinocembrin and 5-hydroxy-7-methoxyflavone, which promoted nuclear translocation and transcriptional activation of AhR and AhR-dependent induction of endogenous target genes.
Assuntos
Modelos Moleculares , Receptores de Hidrocarboneto Arílico/química , Receptores de Hidrocarboneto Arílico/metabolismo , Sequência de Aminoácidos , Animais , Linhagem Celular , Núcleo Celular/metabolismo , Avaliação Pré-Clínica de Medicamentos , Humanos , Ligantes , Camundongos , Dados de Sequência Molecular , Filogenia , Conformação Proteica , Estrutura Terciária de Proteína , Transporte Proteico , Receptores de Hidrocarboneto Arílico/genética , Ativação Transcricional/efeitos dos fármacos , Interface Usuário-ComputadorRESUMO
Histone deacetylase (HDAC) inhibitors are gaining interest as cancer therapeutic agents. We tested the hypothesis that natural organoselenium compounds might be metabolized to HDAC inhibitors in human prostate cancer cells. Se-Methyl-L-selenocysteine (MSC) and selenomethionine are amino acid components of selenium-enriched yeast. In a cell-free system, glutamine transaminase K (GTK) and L-amino acid oxidase convert MSC to the corresponding alpha-keto acid, beta-methylselenopyruvate (MSP), and L-amino acid oxidase converts selenomethionine to its corresponding alpha-keto acid, alpha-keto-gamma-methylselenobutyrate (KMSB). Although methionine (sulfur analogue of selenomethionine) is an excellent substrate for GTK, selenomethionine is poorly metabolized. Structurally, MSP and KMSB resemble the known HDAC inhibitor butyrate. We examined androgen-responsive LNCaP cells and androgen-independent LNCaP C4-2, PC-3, and DU145 cells and found that these human prostate cancer cells exhibit endogenous GTK activities. In the corresponding cytosolic extracts, the metabolism of MSC was accompanied by the concomitant formation of MSP. In MSP-treated and KMSB-treated prostate cancer cell lines, acetylated histone 3 levels increased within 5 hours, and returned to essentially baseline levels by 24 hours, suggesting a rapid, transient induction of histone acetylation. In an in vitro HDAC activity assay, the selenoamino acids, MSC and selenomethionine, had no effect at concentrations up to 2.5 mmol/L, whereas MSP and KMSB both inhibited HDAC activity. We conclude that, in addition to targeting redox-sensitive signaling proteins and transcription factors, alpha-keto acid metabolites of MSC and selenomethionine can alter HDAC activity and histone acetylation status. These findings provide a potential new paradigm by which naturally occurring organoselenium might prevent the progression of human prostate cancer.