RESUMO
Glycosylated sphingolipids (GSLs) are a diverse group of cellular lipids, typically reported as rare in normal mammary tissue. In breast cancer (BCa), GSLs have emerged as noteworthy markers associated with breast cancer stem cells, mediators of phenotypic plasticity, and contributors to cancer cell chemoresistance. GSLs are potential surface markers that can uniquely characterize the heterogeneity of the tumor microenvironment, including cancer cell subpopulations and epithelial-mesenchymal plasticity (EMP). In this study, mass spectrometry analyses of the total sphingolipidome in breast epithelial cells and their mesenchymal counterparts revealed increased levels of Gb3 in epithelial cells and significantly elevated GD2 levels in the mesenchymal phenotype. To elucidate whether GSL-related epitopes on BCa cell surfaces reflect EMP and cancer status, we developed and rigorously validated a 12-color spectral flow cytometry panel. This panel enables the simultaneous detection of native GSL epitopes (Gb3, SSEA1, SSEA3, SSEA4, GD2), epithelial-mesenchymal transition (EMT) markers (EpCAM, TROP2, CD9), and lineage markers (CD45, CD31, CD90) at the single-cell level. As a next step, the established panel was used for the analysis of BCa primary tumors and revealed surface heterogeneity in SSEA1, SSEA3, SSEA4, GD2, and Gb3, indicative of native epitope presence also on non-tumor cells. These findings further highlighted the phenotype-dependent alterations in GSL surface profiles, with differences between epithelial and stromal cells in the tumor. This study provides novel insights into BCa heterogeneity, shedding light on the potential of native GSL-related epitopes as markers for EMP and cancer status in fresh clinical samples. The developed single-cell approach offers promising avenues for further exploration.
RESUMO
Sphingolipids (SLs), glycosphingolipids (GSLs), and eicosanoids are bioactive lipids, which play important roles in the etiology of various diseases, including cancer. However, their content and roles in cancer cells, and in particular in the exosomes derived from tumor cells, remain insufficiently characterized. In this study, we evaluated alterations of SL and GSL levels in transformed cells and their exosomes, using comparative HPLC-MS/MS analysis of parental human bronchial epithelial cells HBEC-12KT and their derivative, benzo[a]pyrene-transformed HBEC-12KT-B1 cells with the acquired mesenchymal phenotype. We examined in parallel SL/GSL contents in the exosomes released from both cell lines. We found significant alterations of the SL/GSL profile in the transformed cell line, which corresponded well with alterations of the SL/GSL profile in exosomes derived from these cells. This suggested that a majority of SLs and GSLs were transported by exosomes in the same relative pattern as in the cells of origin. The only exceptions included decreased contents of sphingosin, sphingosin-1-phosphate, and lactosylceramide in exosomes derived from the transformed cells, as compared with the exosomes derived from the parental cell line. Importantly, we found increased levels of ceramide phosphate, globoside Gb3, and ganglioside GD3 in the exosomes derived from the transformed cells. These positive modulators of epithelial-mesenchymal transition and other pro-carcinogenic processes might thus also contribute to cancer progression in recipient cells. In addition, the transformed HBEC-12KT-B1 cells also produced increased amounts of eicosanoids, in particular prostaglandin E2. Taken together, the exosomes derived from the transformed cells with specifically upregulated SL and GSL species, and increased levels of eicosanoids, might contribute to changes within the cancer microenvironment and in recipient cells, which could in turn participate in cancer development. Future studies should address specific roles of individual SL and GSL species identified in the present study.
Assuntos
Transformação Celular Neoplásica , Exossomos/metabolismo , Mucosa Respiratória/metabolismo , Esfingolipídeos/metabolismo , Benzo(a)pireno/toxicidade , Brônquios/citologia , Carcinógenos/toxicidade , Linhagem Celular , Humanos , Mucosa Respiratória/efeitos dos fármacosRESUMO
The development of colon cancer, one of the most common malignancies, is accompanied with numerous lipid alterations. However, analyses of whole tumor samples may not always provide an accurate description of specific changes occurring directly in tumor epithelial cells. Here, we analyzed in detail the phospholipid (PL), lysophospholipid (lysoPL), and fatty acid (FA) profiles of purified EpCAM+ cells, isolated from tumor and adjacent non-tumor tissues of colon cancer patients. We found that a number of FAs increased significantly in isolated tumor cells, which also included a number of long polyunsaturated FAs. Higher levels of FAs were associated with increased expression of FA synthesis genes, as well as with altered expression of enzymes involved in FA elongation and desaturation, including particularly fatty acid synthase, stearoyl-CoA desaturase, fatty acid desaturase 2 and ELOVL5 fatty acid elongase 5 We identified significant changes in ratios of specific lysoPLs and corresponding PLs. A number of lysophosphatidylcholine and lysophosphatidylethanolamine species, containing long-chain and very-long chain FAs, often with high numbers of double bonds, were significantly upregulated in tumor cells. Increased de novo synthesis of very long-chain FAs, or, altered uptake or incorporation of these FAs into specific lysoPLs in tumor cells, may thus contribute to reprogramming of cellular phospholipidome and membrane alterations observed in colon cancer.
Assuntos
Adenocarcinoma/metabolismo , Neoplasias do Colo/metabolismo , Ácidos Graxos/metabolismo , Regulação Neoplásica da Expressão Gênica , Metabolismo dos Lipídeos , Fosfolipídeos/metabolismo , Adenocarcinoma/enzimologia , Adenocarcinoma/genética , Idoso , Neoplasias do Colo/enzimologia , Neoplasias do Colo/genética , Células Epiteliais/enzimologia , Células Epiteliais/metabolismo , Ácidos Graxos Dessaturases/genética , Ácidos Graxos Dessaturases/metabolismo , Elongases de Ácidos Graxos/genética , Elongases de Ácidos Graxos/metabolismo , Ácido Graxo Sintases/genética , Ácido Graxo Sintases/metabolismo , Feminino , Humanos , Lipidômica , Lipogênese , Masculino , Estearoil-CoA Dessaturase/genética , Estearoil-CoA Dessaturase/metabolismoRESUMO
Nanodiamonds (ND), especially fluorescent NDs, represent potentially applicable drug and probe carriers for in vitro/in vivo applications. The main purpose of this study was to relate physical-chemical properties of carboxylated NDs to their intracellular distribution and impact on membranes and cell immunity-activation of inflammasome in the in vitro THP-1 cell line model. Dynamic light scattering, nanoparticle tracking analysis, and microscopic methods were used to characterize ND particles and their intracellular distribution. Fluorescent NDs penetrated the cell membranes by both macropinocytosis and mechanical cutting through cell membranes. We proved accumulation of fluorescent NDs in lysosomes. In this case, lysosomes were destabilized and cathepsin B was released into the cytoplasm and triggered pathways leading to activation of inflammasome NLRP3, as detected in THP-1 cells. Activation of inflammasome by NDs represents an important event that could underlie the described toxicological effects in vivo induced by NDs. According to our knowledge, this is the first in vitro study demonstrating direct activation of inflammasome by NDs. These findings are important for understanding the mechanism(s) of action of ND complexes and explain the ambiguity of the existing toxicological data.
Assuntos
Inflamassomos/efeitos dos fármacos , Microscopia Intravital/métodos , Lisossomos/efeitos dos fármacos , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Nanodiamantes/administração & dosagem , Catepsina B/imunologia , Catepsina B/metabolismo , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Difusão Dinâmica da Luz , Fluorescência , Humanos , Inflamassomos/imunologia , Inflamassomos/metabolismo , Lisossomos/imunologia , Lisossomos/metabolismo , Lisossomos/ultraestrutura , Microscopia de Força Atômica , Microscopia Confocal , Microscopia Eletrônica , Proteína 3 que Contém Domínio de Pirina da Família NLR/imunologia , Nanodiamantes/química , Pinocitose , Células THP-1RESUMO
OBJECTIVES: This study aimed to assess the biological impact of occupational exposure to diesel exhaust (DE) including DE particles (DEP) from heavy-duty diesel-powered equipment in Norwegian tunnel finishing workers (TFW). METHODS: TFW (n=69) and referents (n=69) were investigated for bulky DNA adducts (by 32P-postlabelling) and expression of microRNAs (miRNAs) (by small RNA sequencing) in peripheral blood mononuclear cells (PBMC), as well as circulating free arachidonic acid (AA) and eicosanoid profiles in plasma (by liquid chromatography-tandem mass spectrometry). RESULTS: PBMC from TFW showed significantly higher levels of DNA adducts compared with referents. Levels of DNA adducts were also related to smoking habits. Seventeen miRNAs were significantly deregulated in TFW. Several of these miRNAs are related to carcinogenesis, apoptosis and antioxidant effects. Analysis of putative miRNA-gene targets revealed deregulation of pathways associated with cancer, alterations in lipid molecules, steroid biosynthesis and cell cycle. Plasma profiles showed higher levels of free AA and 15-hydroxyeicosatetraenoic acid, and lower levels of prostaglandin D2 and 9-hydroxyoctadecadienoic acid in TFW compared with referents. CONCLUSION: Occupational exposure to DE/DEP is associated with biological alterations in TFW potentially affecting lung homoeostasis, carcinogenesis, inflammation status and the cardiovascular system. Of particular importance is the finding that tunnel finishing work is associated with an increased level of DNA adducts formation in PBMC.
Assuntos
Indústria da Construção , Adutos de DNA/sangue , Lipídeos/sangue , MicroRNAs/sangue , Exposição Ocupacional/efeitos adversos , Emissões de Veículos/toxicidade , Adulto , Poluentes Ocupacionais do Ar/análise , Biomarcadores/sangue , Estudos Transversais , Humanos , Exposição por Inalação/análise , Leucócitos Mononucleares/química , Modelos Lineares , Masculino , Pessoa de Meia-Idade , NoruegaRESUMO
Effects of airborne particles on the expression status of markers of cellular toxic stress and on the release of eicosanoids, linked with inflammation and oxidative damage, remain poorly characterized. Therefore, we proposed a set of various methodological approaches in order to address complexity of PM0.5-induced toxicity. For this purpose, we used a well-characterized model of A549 pulmonary epithelial cells exposed to a non-cytotoxic concentration of ambient aerosol particle fraction PM0.5 for 24 h. Electron microscopy confirmed accumulation of PM0.5 within A549 cells, yet, autophagy was not induced. Expression profiles of various cellular stress response genes that have been previously shown to be involved in early stress responses, namely unfolded protein response, DNA damage response, and in aryl hydrocarbon receptor (AhR) and p53 signaling, were analyzed. This analysis revealed induction of GREM1, EGR1, CYP1A1, CDK1A, PUMA, NOXA and GDF15 and suppression of SOX9 in response to PM0.5 exposure. Analysis of eicosanoids showed no oxidative damage and only a weak anti-inflammatory response. In conclusion, this study helps to identify novel gene markers, GREM1, EGR1, GDF15 and SOX9, that may represent a valuable tool for routine testing of PM0.5-induced in vitro toxicity in lung epithelial cells.
Assuntos
Poluentes Atmosféricos/toxicidade , Células Epiteliais/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Pulmão/metabolismo , Material Particulado/toxicidade , Transdução de Sinais/efeitos dos fármacos , Células A549 , Aerossóis , Células Epiteliais/patologia , Humanos , Pulmão/patologiaRESUMO
The development and progression of colorectal cancer (CRC), a major cause of cancer-related death in the western world, is accompanied with alterations of sphingolipid (SL) composition in colon tumors. A number of enzymes involved in the SL metabolism have been found to be deregulated in human colon tumors, in experimental rodent studies, and in human colon cancer cells in vitro. Therefore, the enzymatic pathways that modulate SL levels have received a significant attention, due to their possible contribution to CRC development, or as potential therapeutic targets. Many of these enzymes are associated with an increased sphingosine-1-phosphate/ceramide ratio, which is in turn linked with increased colon cancer cell survival, proliferation and cancer progression. Nevertheless, more attention should also be paid to the more complex SLs, including specific glycosphingolipids, such as lactosylceramides, which can be also deregulated during CRC development. In this review, we focus on the potential roles of individual SLs/SL metabolism enzymes in colon cancer, as well as on the pros and cons of employing the current in vitro models of colon cancer cells for lipidomic studies investigating the SL metabolism in CRC.
Assuntos
Neoplasias do Colo/enzimologia , Regulação Neoplásica da Expressão Gênica , Lactosilceramidas/metabolismo , Metabolismo dos Lipídeos/genética , Esfingolipídeos/metabolismo , Ceramidase Ácida/genética , Ceramidase Ácida/metabolismo , Ceramidase Alcalina/genética , Ceramidase Alcalina/metabolismo , Animais , Ceramidas/metabolismo , Neoplasias do Colo/genética , Neoplasias do Colo/patologia , Modelos Animais de Doenças , Humanos , Lisofosfolipídeos/metabolismo , Ceramidase Neutra/genética , Ceramidase Neutra/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Esfingosina/análogos & derivados , Esfingosina/metabolismo , Esfingosina N-Aciltransferase/genética , Esfingosina N-Aciltransferase/metabolismo , Células Tumorais CultivadasRESUMO
Docosahexaenoic acid (DHA) and sodium butyrate (NaBt) exhibit a number of interactive effects on colon cancer cell growth, differentiation, or apoptosis; however, the molecular mechanisms responsible for these interactions and their impact on cellular lipidome are still not fully clear. Here, we show that both dietary agents together induce dynamic alterations of lipid metabolism, specific cellular lipid classes, and fatty acid composition. In HT-29 cell line, a model of differentiating colon carcinoma cells, NaBt supported incorporation of free DHA into non-polar lipids and their accumulation in cytoplasmic lipid droplets. DHA itself was not incorporated into sphingolipids; however, it significantly altered representation of individual ceramide (Cer) classes, in particular in combination with NaBt (DHA/NaBt). We observed altered expression of enzymes involved in Cer metabolism in cells treated with NaBt or DHA/NaBt, and exogenous Cer 16:0 was found to promote induction of apoptosis in differentiating HT-29 cells. NaBt, together with DHA, increased n-3 fatty acid synthesis and attenuated metabolism of monounsaturated fatty acids. Finally, DHA and/or NaBt altered expression of proteins involved in synthesis of fatty acids, including elongase 5, stearoyl CoA desaturase 1, or fatty acid synthase, with NaBt increasing expression of caveolin-1 and CD36 transporter, which may further promote DHA incorporation and its impact on cellular lipidome. In conclusion, our results indicate that interactions of DHA and NaBt exert complex changes in cellular lipidome, which may contribute to the alterations of colon cancer cell differentiation/apoptotic responses. The present data extend our knowledge about the nature of interactive effects of dietary fatty acids.
Assuntos
Apoptose/efeitos dos fármacos , Butiratos/farmacologia , Diferenciação Celular/efeitos dos fármacos , Neoplasias do Colo/metabolismo , Ácidos Docosa-Hexaenoicos/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipídeos de Membrana/metabolismo , Neoplasias do Colo/patologia , Células HCT116 , Humanos , Lipídeos de Membrana/classificaçãoRESUMO
PURPOSE: Although beneficial effects of the dietary n-3 docosahexaenoic acid (DHA) or butyrate in colon carcinogenesis have been implicated, the mechanisms of their action are not fully clear. Here, we investigated modulations of composition of individual phospholipid (PL) classes, with a particular emphasis on cardiolipins (CLs), in colon cells treated with DHA, sodium butyrate (NaBt), or their combination (DHA/NaBt), and we evaluated possible associations between lipid changes and cell fate after fatty acid treatment. METHODS: In two distinct human colon cell models, foetal colon (FHC) and adenocarcinoma (HCT-116) cells, we compared patterns and composition of individual PL classes following the fatty acid treatment by HPLC-MS/MS. In parallel, we measured the parameters reflecting cell proliferation, differentiation and death. RESULTS: In FHC cells, NaBt induced primarily differentiation, while co-treatment with DHA shifted their response towards cell death. In contrast, NaBt induced apoptosis in HCT-116 cells, which was not further affected by DHA. DHA was incorporated in all main PL types, increasing their unsaturation, while NaBt did not additionally modulate these effects in either cell model. Nevertheless, we identified an unusually wide range of CL species to be highly increased by NaBt and particularly by DHA/NaBt, and these effects were more pronounced in HCT-116 cells. DHA and DHA/NaBt enhanced levels of high molecular weight and more unsaturated CL species, containing DHA, which was specific for either differentiation or apoptotic responses. CONCLUSIONS: We identified a wide range of CL species in the colon cells which composition was significantly modified after DHA and NaBt treatment. These specific CL modulations might contribute to distinct cellular differentiation or apoptotic responses.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Colo/efeitos dos fármacos , Ácidos Docosa-Hexaenoicos/farmacologia , Fosfolipídeos/química , Apoptose/efeitos dos fármacos , Ácido Butírico/farmacologia , Caspase 3/genética , Caspase 3/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Colo/citologia , Células HCT116 , Humanos , Espectrometria de Massas em TandemRESUMO
Butyrate, a short-chain fatty acid produced by fermentation of dietary fiber, is an important regulator of colonic epithelium homeostasis. In this study, we investigated the impact of this histone deacetylase (HDAC) inhibitor on expression/activity of cytochrome P450 family 1 (CYP1) and on metabolism of carcinogenic polycyclic aromatic hydrocarbon, benzo[a]pyrene (BaP), in colon epithelial cells. Sodium butyrate (NaBt) strongly potentiated the BaP-induced expression of CYP1A1 in human colon carcinoma HCT116 cells. It also co-stimulated the 7-ethoxyresorufin-O-deethylase (EROD) activity induced by the 2,3,7,8-tetrachlorodibenzo-p-dioxin, a prototypical ligand of the aryl hydrocarbon receptor. Up-regulation of CYP1A1 expression/activity corresponded with an enhanced metabolism of BaP and formation of covalent DNA adducts. NaBt significantly potentiated CYP1A1 induction and/or metabolic activation of BaP also in other human colon cell models, colon adenoma AA/C1 cells, colon carcinoma HT-29 cells, or in NCM460D cell line derived from normal colon mucosa. Our results suggest that the effects of NaBt were due to its impact on histone acetylation, because additional HDAC inhibitors (trichostatin A and suberanilohydroxamic acid) likewise increased both the induction of EROD activity and formation of covalent DNA adducts. NaBt-induced acetylation of histone H3 (at Lys14) and histone H4 (at Lys16), two histone modifications modulated during activation of CYP1A1 transcription, and it reduced binding of HDAC1 to the enhancer region of CYP1A1 gene. This in vitro study suggests that butyrate, through modulation of histone acetylation, may potentiate induction of CYP1A1 expression, which might in turn alter the metabolism of BaP within colon epithelial cells.
Assuntos
Benzo(a)pireno/farmacocinética , Ácido Butírico/farmacologia , Colo/efeitos dos fármacos , Citocromo P-450 CYP1A1/metabolismo , Benzo(a)pireno/metabolismo , Colo/metabolismo , Citocromo P-450 CYP1A1/genética , Adutos de DNA/efeitos dos fármacos , Adutos de DNA/metabolismo , Elementos Facilitadores Genéticos/efeitos dos fármacos , Células HCT116 , Células HT29 , Histona Desacetilase 1/antagonistas & inibidores , Histona Desacetilase 1/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Histonas/metabolismo , Humanos , Inativação Metabólica , beta Catenina/metabolismoRESUMO
This study used toxicogenomics to identify the complex biological response of human lung BEAS-2B cells treated with organic components of particulate matter in the exhaust of a diesel engine. First, we characterized particles from standard diesel (B0), biodiesel (methylesters of rapeseed oil) in its neat form (B100) and 30% by volume blend with diesel fuel (B30), and neat hydrotreated vegetable oil (NEXBTL100). The concentration of polycyclic aromatic hydrocarbons (PAHs) and their derivatives in organic extracts was the lowest for NEXBTL100 and higher for biodiesel. We further analyzed global gene expression changes in BEAS-2B cells following 4 h and 24 h treatment with extracts. The concentrations of 50 µg extract/mL induced a similar molecular response. The common processes induced after 4 h treatment included antioxidant defense, metabolism of xenobiotics and lipids, suppression of pro-apoptotic stimuli, or induction of plasminogen activating cascade; 24 h treatment affected fewer processes, particularly those involved in detoxification of xenobiotics, including PAHs. The majority of distinctively deregulated genes detected after both 4 h and 24 h treatment were induced by NEXBTL100; the deregulated genes included, e.g., those involved in antioxidant defense and cell cycle regulation and proliferation. B100 extract, with the highest PAH concentrations, additionally affected several cell cycle regulatory genes and p38 signaling.
Assuntos
Biocombustíveis/toxicidade , Gasolina/toxicidade , Regulação da Expressão Gênica de Plantas , Material Particulado/toxicidade , Proteínas de Plantas/genética , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Poluentes Atmosféricos/análise , Poluentes Atmosféricos/toxicidade , Biocombustíveis/análise , Brônquios/citologia , Brônquios/efeitos dos fármacos , Brônquios/metabolismo , Linhagem Celular Transformada , Células Epiteliais/citologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Gasolina/análise , Perfilação da Expressão Gênica , Humanos , Anotação de Sequência Molecular , Material Particulado/análise , Óleos de Plantas/química , Proteínas de Plantas/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/análise , Transdução de Sinais , Emissões de Veículos/análiseRESUMO
We investigated the toxicity of benzo[a]pyrene (B[a]P), 1-nitropyrene (1-NP) and 3-nitrobenzanthrone (3-NBA) in A549 cells. Cells were treated for 4 h and 24 h with: B[a]P (0.1 and 1 µM), 1-NP (1 and 10 µM) and 3-NBA (0.5 and 5 µM). Bulky DNA adducts, lipid peroxidation, DNA and protein oxidation and mRNA expression of CYP1A1, CYP1B1, NQO1, POR, AKR1C2 and COX2 were analyzed. Bulky DNA adducts were induced after both treatment periods; the effect of 1-NP was weak. 3-NBA induced high levels of bulky DNA adducts even after 4-h treatment, suggesting rapid metabolic activation. Oxidative DNA damage was not affected. 1-NP caused protein oxidation and weak induction of lipid peroxidation after 4-h incubation. 3-NBA induced lipid peroxidation after 24-h treatment. Unlike B[a]P, induction of the aryl hydrocarbon receptor, measured as mRNA expression levels of CYP1A1 and CYP1B1, was low after treatment with polycyclic aromatic hydrocarbon (PAH) nitro-derivatives. All test compounds induced mRNA expression of NQO1, POR, and AKR1C2 after 24-h treatment. AKR1C2 expression indicates involvement of processes associated with reactive oxygen species generation. This was supported further by COX2 expression induced by 24-h treatment with 1-NP. In summary, 3-NBA was the most potent genotoxicant, whereas 1-NP exhibited the strongest oxidative properties.
Assuntos
Células Epiteliais Alveolares/efeitos dos fármacos , Emissões de Veículos/toxicidade , Células A549 , Células Epiteliais Alveolares/metabolismo , Benzo(a)Antracenos/toxicidade , Benzo(a)pireno/toxicidade , Ciclo-Oxigenase 2/genética , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP1B1/genética , Sistema Enzimático do Citocromo P-450/genética , Adutos de DNA/efeitos dos fármacos , Adutos de DNA/genética , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/genética , Humanos , Hidroxiesteroide Desidrogenases/genética , NAD(P)H Desidrogenase (Quinona)/genética , Pirenos/toxicidadeRESUMO
ß-Arrestin is a scaffold protein that regulates signal transduction by seven transmembrane-spanning receptors. Among other functions it is also critically required for Wnt/ß-catenin signal transduction. In the present study we provide for the first time a mechanistic basis for the ß-arrestin function in Wnt/ß-catenin signaling. We demonstrate that ß-arrestin is required for efficient Wnt3a-induced Lrp6 phosphorylation, a key event in downstream signaling. ß-Arrestin regulates Lrp6 phosphorylation via a novel interaction with phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2)-binding protein Amer1/WTX/Fam123b. Amer1 has been shown very recently to bridge Wnt-induced and Dishevelled-associated PtdIns(4,5)P2 production to the phosphorylation of Lrp6. Using fluorescence recovery after photobleaching we show here that ß-arrestin is required for the Wnt3a-induced Amer1 membrane dynamics and downstream signaling. Finally, we show that ß-arrestin interacts with PtdIns kinases PI4KIIα and PIP5KIß. Importantly, cells lacking ß-arrestin showed higher steady-state levels of the relevant PtdInsP and were unable to increase levels of these PtdInsP in response to Wnt3a. In summary, our data show that ß-arrestins regulate Wnt3a-induced Lrp6 phosphorylation by the regulation of the membrane dynamics of Amer1. We propose that ß-arrestins via their scaffolding function facilitate Amer1 interaction with PtdIns(4,5)P2, which is produced locally upon Wnt3a stimulation by ß-arrestin- and Dishevelled-associated kinases.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Arrestinas/metabolismo , Membrana Celular/metabolismo , Proteína-6 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Proteína Wnt3A/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Arrestinas/genética , Western Blotting , Células Cultivadas , Proteínas Desgrenhadas , Embrião de Mamíferos/citologia , Fibroblastos/citologia , Fibroblastos/metabolismo , Células HEK293 , Humanos , Proteína-6 Relacionada a Receptor de Lipoproteína de Baixa Densidade/genética , Camundongos , Camundongos Knockout , Microscopia Confocal , Antígenos de Histocompatibilidade Menor , Fosfatidilinositol 4,5-Difosfato/metabolismo , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Fosforilação , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Ligação Proteica , Interferência de RNA , Proteínas Supressoras de Tumor/genética , Proteína Wnt3A/genética , beta-ArrestinasRESUMO
Docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid present in fish oil, may exert cytotoxic and/or cytostatic effects on colon cancer cells when applied individually or in combination with some anticancer drugs. Here we demonstrate a selective ability of subtoxic doses of DHA to enhance antiproliferative and apoptotic effects of clinically useful cytokine TRAIL (tumor necrosis factor-related apoptosis inducing ligand) in cancer but not normal human colon cells. DHA-mediated stimulation of TRAIL-induced apoptosis was associated with extensive engagement of mitochondrial pathway (Bax/Bak activation, drop of mitochondrial membrane potential, cytochrome c release), activation of endoplasmic reticulum stress response (CHOP upregulation, changes in PERK level), decrease of cellular inhibitor of apoptosis protein (XIAP, cIAP1) levels and significant changes in sphingolipid metabolism (intracellular levels of ceramides, hexosyl ceramides, sphingomyelines, sphingosines; HPLC/MS/MS). Interestingly, we found significant differences in representation of various classes of ceramides (especially C16:0, C24:1) between the cancer and normal colon cells treated with DHA and TRAIL, and suggested their potential role in the regulation of the cell response to the drug combination. These study outcomes highlight the potential of DHA for a new combination therapy with TRAIL for selective elimination of colon cancer cells via simultaneous targeting of multiple steps in apoptotic pathways.
Assuntos
Ácidos Docosa-Hexaenoicos/farmacologia , Regulação Neoplásica da Expressão Gênica , Mitocôndrias/efeitos dos fármacos , Esfingolipídeos/metabolismo , Ligante Indutor de Apoptose Relacionado a TNF/farmacologia , Adenocarcinoma/genética , Adenocarcinoma/metabolismo , Adenocarcinoma/patologia , Apoptose/efeitos dos fármacos , Apoptose/genética , Linhagem Celular Tumoral , Neoplasias do Colo/genética , Neoplasias do Colo/metabolismo , Neoplasias do Colo/patologia , Citocromos c/metabolismo , Sinergismo Farmacológico , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Humanos , Proteínas Inibidoras de Apoptose , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/metabolismo , Transdução de Sinais , Esfingolipídeos/química , Esfingolipídeos/classificação , Fator de Transcrição CHOP/genética , Fator de Transcrição CHOP/metabolismo , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo X/genética , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo X/metabolismo , Proteína Killer-Antagonista Homóloga a bcl-2/genética , Proteína Killer-Antagonista Homóloga a bcl-2/metabolismo , Proteína X Associada a bcl-2/genética , Proteína X Associada a bcl-2/metabolismo , eIF-2 Quinase/genética , eIF-2 Quinase/metabolismoRESUMO
Consensus toxicity factors (CTFs) were developed as a novel approach to establish toxicity factors for risk assessment of dioxin-like compounds (DLCs). Eighteen polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs), and biphenyls (PCBs) with assigned World Health Organization toxic equivalency factors (WHO-TEFs) and two additional PCBs were screened in 17 human and rodent bioassays to assess their induction of aryl hydrocarbon receptor-related responses. For each bioassay and compound, relative effect potency values (REPs) compared to 2,3,7,8-tetrachlorodibenzo-p-dioxin were calculated and analyzed. The responses in the human and rodent cell bioassays generally differed. Most notably, the human cell models responded only weakly to PCBs, with 3,3',4,4',5-pentachlorobiphenyl (PCB126) being the only PCB that frequently evoked sufficiently strong responses in human cells to permit us to calculate REP values. Calculated REPs for PCB126 were more than 30 times lower than the WHO-TEF value for PCB126. CTFs were calculated using score and loading vectors from a principal component analysis to establish the ranking of the compounds and, by rescaling, also to provide numerical differences between the different congeners corresponding to the TEF scheme. The CTFs were based on rat and human bioassay data and indicated a significant deviation for PCBs but also for certain PCDD/Fs from the WHO-TEF values. The human CTFs for 2,3,4,7,8-pentachlorodibenzofuran, 1,2,3,4,7,8-hexachlorodibenzofuran, 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin, and 1,2,3,4,7,8,9-heptachlorodibenzofuran were up to 10 times greater than their WHO-TEF values. Quantitative structure-activity relationship models were used to predict CTFs for untested WHO-TEF compounds, suggesting that the WHO-TEF value for 1,2,3,7,8-pentachlorodibenzofuran could be underestimated by an order of magnitude for both human and rodent models. Our results indicate that the CTF approach provides a powerful tool for condensing data from batteries of screening tests using compounds with similar mechanisms of action, which can be used to improve risk assessment of DLCs.
Assuntos
Benzofuranos/toxicidade , Bifenilos Policlorados/toxicidade , Dibenzodioxinas Policloradas/análogos & derivados , Receptores de Hidrocarboneto Arílico/fisiologia , Animais , Benzofuranos/química , Simulação por Computador , Dibenzofuranos Policlorados , Humanos , Técnicas In Vitro , Bifenilos Policlorados/química , Dibenzodioxinas Policloradas/química , Dibenzodioxinas Policloradas/toxicidade , Relação Quantitativa Estrutura-Atividade , Ratos , RoedoresRESUMO
Deregulation of Wnt/ß-catenin signalling plays an important role in the pathogenesis of colorectal cancer. Interestingly, this pathway has been recently implicated in transcriptional control of cytochrome P450 (CYP) family 1 enzymes, which are responsible for bioactivation of a number of dietary carcinogens. In the present study, we investigated the impact of inhibition of Wnt/ß-catenin pathway on metabolism and genotoxicity of benzo[a]pyrene (BaP), a highly mutagenic polycyclic aromatic hydrocarbon and an efficient ligand of the aryl hydrocarbon receptor, which is known as a primary regulator of CYP1 expression, in cellular models derived from colorectal tumours. We observed that a synthetic inhibitor of ß-catenin, JW74, significantly increased formation of BaP-induced DNA adducts in both colorectal adenoma and carcinoma-derived cell lines. Using the short interfering RNA (siRNA) targeting ß-catenin, we then found that ß-catenin knockdown in HCT116 colon carcinoma cells significantly enhanced formation of covalent DNA adducts by BaP and histone H2AX phosphorylation, as detected by (32)P-postlabelling technique and immunocytochemistry, respectively, and it also induced expression of DNA damage response genes, such as CDKN1A or DDB2. The increased formation of DNA adducts formed by BaP upon ß-catenin knockdown corresponded with enhanced production of major BaP metabolites, as well as with an increased expression/activity of CYP1 enzymes. Finally, using siRNA-mediated knockdown of CYP1A1, we confirmed that this enzyme plays a major role in formation of BaP-induced DNA adducts in HCT116 cells. Taken together, the present results indicated that the siRNA-mediated inhibition of ß-catenin signalling, which is aberrantly activated in a majority of colorectal cancers, modulated genotoxicity of dietary carcinogen BaP in colon cell model in vitro, via a mechanism involving up-regulation of CYP1 expression and activity.
Assuntos
Benzo(a)pireno/efeitos adversos , Neoplasias do Colo/etiologia , Neoplasias do Colo/patologia , Citocromo P-450 CYP1A1/metabolismo , Adutos de DNA/efeitos adversos , Dano ao DNA , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , beta Catenina/antagonistas & inibidores , Apoptose , Western Blotting , Carcinógenos Ambientais/efeitos adversos , Proliferação de Células , Neoplasias do Colo/tratamento farmacológico , Citocromo P-450 CYP1A1/antagonistas & inibidores , Citocromo P-450 CYP1A1/genética , Humanos , Técnicas Imunoenzimáticas , RNA Mensageiro/genética , RNA Interferente Pequeno/genética , Reação em Cadeia da Polimerase em Tempo Real , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células Tumorais Cultivadas , beta Catenina/genética , beta Catenina/metabolismoRESUMO
Cytochrome P450 1B1 (CYP1B1) is an enzyme that has a unique tumor-specific pattern of expression and is capable of bioactivating a wide range of carcinogenic compounds. We have reported previously that coordinated upregulation of CYP1B1 by inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and the aryl hydrocarbon receptor ligands, may increase bioactivation of promutagens, such as benzo[a]pyrene (BaP) in epithelial cells. Here, we extend those studies by describing a novel mechanism participating in the regulation of CYP1B1 expression, which involves activation of the p38 mitogen-activated protein kinase (p38) and mitogen- and stress-activated protein kinase 1 (MSK1). Using inhibitors of p38 and MSKs, as well as mouse embryonic cells derived from p38α-deficient and MSK1/2 double knockout mice, we show here that TNF-α potentiates CYP1B1 upregulation via the p38/MSK1 kinase cascade. Effects of this inflammatory cytokine on CYP1B1 expression further involve the positive transcription elongation factor b (P-TEFb). The inhibition of the P-TEFb subunit, cyclin-dependent kinase 9 (CDK9), which phosphorylates RNA polymerase II (RNAPII), prevented the enhanced CYP1B1 induction by a combination of BaP and inflammatory cytokine. Furthermore, using chromatin immunoprecipitation assays, we found that cotreatment of epithelial cells with TNF-α and BaP resulted in enhanced recruitment of both CDK9 and RNAPII to the Cyp1b1 gene promoter. Overall, these results have implications concerning the contribution of inflammatory factors to carcinogenesis, since enhanced CYP1B1 induction during inflammation may alter metabolism of exogenous carcinogens, as well as endogenous CYP1B1 substrates playing role in tumor development.
Assuntos
Carcinogênese/genética , Citocromo P-450 CYP1B1/biossíntese , Neoplasias/genética , Proteínas Quinases p38 Ativadas por Mitógeno/genética , Animais , Carcinogênese/efeitos dos fármacos , Carcinógenos/toxicidade , Quinase 9 Dependente de Ciclina/genética , Citocromo P-450 CYP1B1/genética , Citocinas/metabolismo , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Camundongos , Neoplasias/induzido quimicamente , Neoplasias/patologia , Fator B de Elongação Transcricional Positiva/genética , RNA Polimerase II/genética , Transdução de Sinais/efeitos dos fármacos , Fator de Necrose Tumoral alfa/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
For a better understanding of species-specific relative effect potencies (REPs), responses of dioxin-like compounds (DLCs) were assessed. REPs were calculated using chemical-activated luciferase gene expression assays (CALUX) derived from guinea pig, rat, and mouse cell lines. Almost all 20 congeners tested in the rodent cell lines were partial agonists and less efficacious than 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). For this reason, REPs were calculated for each congener using concentrations at which 20% of the maximal TCDD response was reached (REP20TCDD). REP20TCDD values obtained for PCDD/Fs were comparable with their toxic equivalency factors assigned by the World Health Organization (WHO-TEF), while those for PCBs were in general lower than the WHO-TEF values. Moreover, the guinea pig cell line was the most sensitive as indicated by the 20% effect concentrations of TCDD of 1.5, 5.6, and 11.0 pM for guinea pig, rat, and mouse cells, respectively. A similar response pattern was observed using multivariate statistical analysis between the three CALUX assays and the WHO-TEFs. The mouse assay showed minor deviation due to higher relative induction potential for 2,3,7,8-tetrachlorodibenzofuran and 2,3,4,6,7,8-hexachlorodibenzofuran and lower for 1,2,3,4,6,7,8-heptachlorodibenzofuran and 3,3',4,4',5-pentachlorobiphenyl (PCB126). 2,3,7,8-Tetrachlorodibenzofuran was more than two times more potent in the mouse assay as compared with that of rat and guinea pig cells, while measured REP20TCDD for PCB126 was lower in mouse cells (0.05) as compared with that of the guinea pig (0.2) and rat (0.07). In order to provide REP20TCDD values for all WHO-TEF assigned compounds, quantitative structure-activity relationship (QSAR) models were developed. The QSAR models showed that specific electronic properties and molecular surface characteristics play important roles in the AhR-mediated response. In silico derived REP20TCDD values were generally consistent with the WHO-TEFs with a few exceptions. The QSAR models indicated that, e.g., 1,2,3,7,8-pentachlorodibenzofuran and 1,2,3,7,8,9-hexachlorodibenzofuran were more potent than given by their assigned WHO-TEF values, and the non-ortho PCB 81 was predicted, based on the guinea-pig model, to be 1 order of magnitude above its WHO-TEF value. By combining in vitro and in silico approaches, REPs were established for all WHO-TEF assigned compounds (except OCDD), which will provide future guidance in testing AhR-mediated responses of DLCs and to increase our understanding of species variation in AhR-mediated effects.
Assuntos
Benzofuranos/farmacologia , Bifenilos Policlorados/farmacologia , Dibenzodioxinas Policloradas/análogos & derivados , Receptores de Hidrocarboneto Arílico/metabolismo , Animais , Bioensaio , Linhagem Celular Tumoral , Simulação por Computador , Dibenzofuranos Policlorados , Relação Dose-Resposta a Droga , Cobaias , Luciferases/metabolismo , Camundongos , Modelos Biológicos , Dibenzodioxinas Policloradas/farmacologia , Relação Quantitativa Estrutura-Atividade , Ratos , Receptores de Hidrocarboneto Arílico/agonistasRESUMO
The life cycle of enveloped viruses is closely linked to host-cell lipids. However, changes in lipid metabolism during infections with the tick-borne encephalitis virus (TBEV) have not been described. TBEV is a medically important orthoflavivirus, which is endemic to many parts of Europe and Asia. In the present study, we performed targeted lipidomics with HPLC-MS/MS to evaluate changes in phospholipid and sphingolipid concentrations in TBEV-infected human neuronal SK-N-SH cells. TBEV infections significantly increased phosphatidylcholine, phosphatidylinositol, and phosphatidylserine levels within 48 h post-infection (hpi). Sphingolipids were slightly increased in dihydroceramides within 24 hpi. Later, at 48 hpi, the contents of sphinganine, dihydroceramides, ceramides, glucosylceramides, and ganglioside GD3 were elevated. On the other hand, sphingosine-1-phosphate content was slightly reduced in TBEV-infected cells. Changes in sphingolipid concentrations were accompanied by suppressed expression of a majority of the genes linked to sphingolipid and glycosphingolipid metabolism. Furthermore, we found that a pharmacological inhibitor of sphingolipid synthesis, fenretinide (4-HPR), inhibited TBEV infections in SK-N-SH cells. Taken together, our results suggested that both structural and signaling functions of lipids could be affected during TBEV infections. These changes might be connected to virus propagation and/or host-cell defense.