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While the role of transcription factors and coactivators in controlling enhancer activity and chromatin structure linked to gene expression is well established, the involvement of corepressors is not. Using inflammatory macrophage activation as a model, we investigate here a corepressor complex containing GPS2 and SMRT both genome-wide and at the Ccl2 locus, encoding the chemokine CCL2 (MCP-1). We report that corepressors co-occupy candidate enhancers along with the coactivators CBP (H3K27 acetylase) and MED1 (mediator) but act antagonistically by repressing eRNA transcription-coupled H3K27 acetylation. Genome editing, transcriptional interference, and cistrome analysis reveals that apparently related enhancer and silencer elements control Ccl2 transcription in opposite ways. 4C-seq indicates that corepressor depletion or inflammatory signaling functions mechanistically similarly to trigger enhancer activation. In ob/ob mice, adipose tissue macrophage-selective depletion of the Ccl2 enhancer-transcribed eRNA reduces metaflammation. Thus, the identified corepressor-eRNA-chemokine pathway operates in vivo and suggests therapeutic opportunities by targeting eRNAs in immuno-metabolic diseases.
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Quimiocina CCL2/genética , Proteínas Correpressoras/genética , Elementos Facilitadores Genéticos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Correpressor 2 de Receptor Nuclear/genética , Obesidade/genética , Elementos Silenciadores Transcricionais , Tecido Adiposo/imunologia , Tecido Adiposo/patologia , Animais , Sistemas CRISPR-Cas , Quimiocina CCL2/imunologia , Proteínas Correpressoras/imunologia , Edição de Genes , Regulação da Expressão Gênica/efeitos dos fármacos , Células HEK293 , Histona Acetiltransferases/genética , Histona Acetiltransferases/imunologia , Histonas/genética , Histonas/imunologia , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/imunologia , Lipopolissacarídeos/farmacologia , Ativação de Macrófagos/efeitos dos fármacos , Masculino , Subunidade 1 do Complexo Mediador/genética , Subunidade 1 do Complexo Mediador/imunologia , Camundongos , Camundongos Obesos , Correpressor 2 de Receptor Nuclear/imunologia , Obesidade/imunologia , Obesidade/patologia , Células RAW 264.7 , RNA não Traduzido/genética , RNA não Traduzido/imunologia , Transdução de SinaisRESUMO
BACKGROUND: Pancreatic neuroendocrine tumors are rare neoplasms for which few predictive and/or prognostic biomarkers have been validated. Our previous work suggested the potential of the combined expression of N-myc downstream-regulated gen-1 (NDRG-1), O6-methylguanine DNA methyltransferase (MGMT) and Pleckstrin homology-like domain family A member 3 (PHLDA-3) as prognostic factors for relapse and survival. METHODS: In this new multicenter study we evaluated immunohistochemistry expression in 76 patients with advanced PanNET who were treated with capecitabine-temozolomide or everolimus. Based on the immunohistochemistry panel, an immunohistochemistry prognostic score (IPS) was developed. RESULTS: In patients treated with capecitabine and temozolomide, low IPS was an independent prognostic factor for progression-free-survival and overall-survival. Similar findings were observed with highest IPS for overall-survival in patients treated with everolimus. CONCLUSION: From our knowledge, it is the first time that a simple IPS could be useful to predict outcome for patients with metastatic pancreatic neuroendocrine tumors treated with everolimus or capecitabine and temozolomide.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Everolimo/uso terapêutico , Imuno-Histoquímica/métodos , Imunossupressores/uso terapêutico , Tumores Neuroendócrinos/tratamento farmacológico , Tumores Neuroendócrinos/patologia , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/análise , Proteínas de Ciclo Celular/análise , Linhagem Celular Tumoral , Metilases de Modificação do DNA/análise , Enzimas Reparadoras do DNA/análise , Feminino , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/análise , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia , Tumores Neuroendócrinos/mortalidade , Proteínas Nucleares/análise , Neoplasias Pancreáticas/mortalidade , Prognóstico , Intervalo Livre de Progressão , Análise de Sobrevida , Proteínas Supressoras de Tumor/análise , Adulto JovemRESUMO
Cancer is a complex disease involving alterations of multiple processes, with both genetic and epigenetic features contributing as core factors to the disease. In recent years, it has become evident that non-coding RNAs (ncRNAs), an epigenetic factor, play a key role in the initiation and progression of cancer. MicroRNAs, the most studied non-coding RNAs subtype, are key controllers in a myriad of cellular processes, including proliferation, differentiation, and apoptosis. Furthermore, the expression of miRNAs is controlled, concomitantly, by other epigenetic factors, such as DNA methylation and histone modifications, resulting in aberrant patterns of expression upon the occurrence of cancer. In this sense, aberrant miRNA landscape evaluation has emerged as a promising strategy for cancer management. In this review, we have focused on the regulation (biogenesis, processing, and dysregulation) of miRNAs and their role as modulators of the epigenetic machinery. We have also highlighted their potential clinical value, such as validated diagnostic and prognostic biomarkers, and their relevant role as chromatin modifiers in cancer therapy.
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Epigênese Genética , MicroRNAs/genética , Neoplasias/genética , RNA Neoplásico/genética , Pesquisa Translacional Biomédica , Biomarcadores Tumorais , Neoplasias da Mama/genética , Metilação de DNA , DNA de Neoplasias/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Terapia Genética , Código das Histonas , Humanos , Neoplasias Pulmonares/genética , MicroRNAs/biossíntese , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Neoplasias/metabolismo , Neoplasias/terapia , Neoplasias Ovarianas/genética , Prognóstico , Processamento Pós-Transcricional do RNA , RNA Neoplásico/biossíntese , Neoplasias Gástricas/genéticaRESUMO
Within the past two decades, coregulators have emerged as essential chromatin components of metabolic signaling by nuclear receptors and additional metabolite-sensing transcription factors. Intriguingly, coregulators themselves are efficient sensors and effectors of metabolic stimuli that modulate gene expression at different levels, often via post-translational modifications of histones or other factors. There is already evidence that alterations of expression or function of coregulators contributes to metabolic disease by propagating disease-specific epigenomes linked to the dysregulation of transcription and downstream pathways. In this chapter we review the current progress made in understanding the role of coregulators in metabolic pathways, with a particular emphasis on their study in vivo and in the context of metabolic disease.
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Doenças Metabólicas/etiologia , Receptores Citoplasmáticos e Nucleares/fisiologia , Tecido Adiposo/metabolismo , Animais , Metabolismo Energético , Humanos , Resistência à Insulina , Músculo Esquelético/metabolismo , Especificidade de Órgãos , Processamento de Proteína Pós-Traducional , Transdução de SinaisRESUMO
Type 2 diabetes (T2D) is a complex metabolic disease, which involves maintained hyperglycemia, mainly due to the development of an insulin resistance process. Metformin administration is the most prescribed treatment for diabetic patients. In a previously published study, we demonstrated that Pediococcus acidilactici pA1c® (pA1c) protects from insulin resistance and body weight gain in HFD-induced diabetic mice. The present work aimed to evaluate the possible beneficial impact of a 16-week administration of pA1c, metformin, or the combination of pA1c and metformin in a T2D HFD-induced mice model. We found that the simultaneous administration of both products attenuated hyperglycemia, increased high-intensity insulin-positive areas in the pancreas and HOMA-ß, decreased HOMA-IR and also provided more beneficial effects than metformin treatment (regarding HOMA-IR, serum C-peptide level, liver steatosis or hepatic Fasn expression), and pA1c treatment (regarding body weight or hepatic G6pase expression). The three treatments had a significant impact on fecal microbiota and led to differential composition of commensal bacterial populations. In conclusion, our findings suggest that P. acidilactici pA1c® administration improved metformin beneficial effects as a T2D treatment, and it would be a valuable therapeutic strategy to treat T2D.
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BACKGROUND: Identification of predictive biomarkers to Immune checkpoint inhibitors (ICIs) in head and neck cancer (HNSCC) is an unmet need. METHODS: This was a prospective observational study including 25 patients with HNSCC treated with immunotherapy or chemotherapy after a prior platinum-based regimen. Low density neutrophils (LDNs) and serum markers were analyzed. RESULTS: In the immunotherapy cohort, patients with high LDN levels had a shorter progression free survival (PFS) (1.8 months vs. 10.9 months; *p = 0.034). Also, progressors showed higher percentage of LDNs compared to non-progressors although significance was not reached (mean 20.68% vs. 4.095%, p = 0.0875). These findings were not replicated in patients treated with chemotherapy. High levels of interleukin-7 (IL7) were correlated with a significantly longer overall survival (OS) (13.47 months 3.51 vs. months, *p = 0.013). CONCLUSIONS: High baseline circulating LDNs and low IL7 could identify a subset of patients intrinsically refractory to ICIs as monotherapy in HNSCC.
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Neoplasias de Cabeça e Pescoço , Interleucina-7 , Humanos , Carcinoma de Células Escamosas de Cabeça e Pescoço/terapia , Carcinoma de Células Escamosas de Cabeça e Pescoço/etiologia , Neutrófilos , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/etiologia , Biomarcadores , Imunoterapia/efeitos adversosRESUMO
UNLABELLED: The identification of molecular mechanisms involved in the maintenance of the transformed phenotype of hepatocellular carcinoma (HCC) cells is essential for the elucidation of therapeutic strategies. Here, we show that human HCC cells display an autocrine loop mediated by connective tissue growth factor (CTGF) that promotes DNA synthesis and cell survival. Expression of CTGF was stimulated by epidermal growth factor receptor (EGFR) ligands and was dependent on the expression of the transcriptional coactivator, Yes-associated protein (YAP). We identified elements in the CTGF gene proximal promoter that bound YAP-enclosing complexes and were responsible for basal and EGFR-stimulated CTGF expression. We also demonstrate that YAP expression can be up-regulated through EGFR activation not only in HCC cells, but also in primary human hepatocytes. CTGF contributed to HCC cell dedifferentiation, expression of inflammation-related genes involved in carcinogenesis, resistance toward doxorubicin, and in vivo HCC cell growth. Importantly, CTGF down-regulated tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor 2 expression and was involved in the reduced sensitivity of these cells toward TRAIL-mediated apoptosis. CONCLUSION: We have identified autocrine CTGF as a novel determinant of HCC cells' neoplastic behavior. Expression of CTGF can be stimulated through the EGFR-signaling system in HCC cells in a novel cross-talk with the oncoprotein YAP. Moreover, to our knowledge, this is the first study that identifies a signaling mechanism triggering YAP gene expression in healthy and transformed liver parenchymal cells.
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Comunicação Autócrina/fisiologia , Carcinoma Hepatocelular/fisiopatologia , Fator de Crescimento do Tecido Conjuntivo/fisiologia , Receptores ErbB/fisiologia , Neoplasias Hepáticas/fisiopatologia , Proteínas Nucleares/fisiologia , Fatores de Transcrição/fisiologia , Proteínas de Ciclo Celular , Fator de Crescimento do Tecido Conjuntivo/biossíntese , Doxorrubicina/farmacologia , Resistencia a Medicamentos Antineoplásicos , Hepatócitos/metabolismo , Humanos , Proteínas Nucleares/biossíntese , Cultura Primária de Células , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/biossíntese , Fatores de Transcrição/biossínteseRESUMO
Despite its relative low incidence, PDAC is one of the most aggressive and lethal types of cancer, being currently the seventh leading cause of cancer death worldwide, with a 5-year survival rate of 10.8%. Taking into consideration the necessity to improve the prognosis of these patients, this research has been focused on the discovery of new biomarkers. For this purpose, patients with BL and resectable disease were recruited. Serum cytokines and growth factors were monitored at different time points using protein arrays. Immune cell populations were determined by flow cytometry in peripheral blood as well as by immunohistochemistry (IHC) in tumor tissues. Several cytokines were found to be differentially expressed between the study subgroups. In the BL disease setting, two different scores were proven to be independent prognostic factors for progression-free survival (PFS) (based on IL-10, MDC, MIF, and eotaxin-3) and OS (based on eotaxin-3, NT-3, FGF-9, and IP10). In the same context, CA19-9 was found to play a role as independent prognostic factor for OS. Eotaxin-3 and MDC cytokines for PFS, and eotaxin-3, NT-3, and CKß8-1 for OS, were shown to be predictive biomarkers for nab-paclitaxel and gemcitabine regimen. Similarly, oncostatin, BDNF, and IP10 cytokines were proven to act as predictive biomarkers regarding PFS, for FOLFIRINOX regimen. In the resectable cohort, RANTES, TIMP-1, FGF-4, and IL-10 individually differentiated patients according to their cancer-associated survival. Regarding immune cell populations, baseline high levels of circulating B lymphocytes were related to a significantly longer OS, while these levels significantly decreased as progression occurred. Similarly, baseline high levels of helper lymphocytes (CD4+), low levels of cytotoxic lymphocytes (CD8+), and a high CD4/CD8 ratio, were related to a significantly longer PFS. Finally, high levels of CD4+ and CD8+ intratumoural infiltration was associated with significantly longer PFS. In conclusion, in this study we were able to identify several prognostic and predictive biomarker candidates in patients diagnosed of resectable or BL PDAC.
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Checkpoint with forkhead-associated and ring finger domains (CHFR) has been proposed as a predictive and prognosis biomarker for different tumor types, but its role in pancreatic ductal adenocarcinoma (PDAC) remains unknown. The aim of this study was two-pronged: to review the role of CHFR in PDAC and evaluating CHFR as a potential predictive biomarker in this disease. For this purpose, we first explored the CHFR messenger (m)RNA expression and promoter methylation through the TCGA database. Secondly, the CHFR expression and promoter methylation were prospectively evaluated in a cohort of patients diagnosed with borderline (n = 19) or resectable (n = 16) PDAC by immunohistochemistry (IHC), methylation specific-PCR (MSP), and pyrosequencing. The results from the TCGA database showed significant differences in terms of progression-free survival (PFS) and overall survival (OS) based on the CHFR mRNA expression, which was likely independent from the promoter methylation. Importantly, our results showed that in primarily resected patients and also the entire cohort, a higher CHFR expression as indicated by the higher IHC staining intensity might identify patients with longer disease-free survival (DFS) and OS, respectively. Similarly, in the same cohorts, patients with lower methylation levels by pyrosequencing showed significantly longer OS than patients without this pattern. Both, the CHFR expression intensity and its promoter methylation were established as independent prognostic factors for PFS and OS in the entire cohort. In contrast, no significant differences were found between different methylation patterns for CHFR and the response to taxane-based neoadjuvant treatment. These results suggest the potential role of the higher expression of CHFR and the methylation pattern of its promoter as potential prognostic biomarkers in PDAC, thus warranting further comprehensive studies to extend and confirm our preliminary findings.
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BACKGROUND & AIMS: Inactivation of the product of the tumor suppressor gene TP73 does not usually occur by mutation but rather through expression of truncated isoforms that have dominant-negative effects on p73 and p53. The truncated oncogenic isoform DeltaEx2p73 is expressed in hepatocellular carcinomas (HCC) and is produced through the alternative splicing of p73 pre-messenger RNA (pre-mRNA); however, the underlying mechanisms regulating this process are unknown. METHODS: We used human normal and diseased liver tissue samples, as well as human HCC cell lines, to examine the association between activation of epidermal growth factor receptor (EGFR) by its ligand amphiregulin (AR) and the alternative splicing of p73 pre-mRNA into the tumorigenic isoform DeltaEx2p73, via c-Jun N-terminal-kinase-1-mediated signaling. RESULTS: DeltaEx2p73 was expressed in a subset of premalignant cirrhotic livers and in otherwise healthy livers that harbored a primary tumor, as well as in HCC tissues. DeltaEx2p73 expression was correlated with that of the EGFR ligand AR, which was previously shown to have a role in hepatocarcinogenesis. Autocrine activation of the EGFR by AR triggered c-Jun N-terminal kinase-1 activity and inhibited the expression of the splicing regulator Slu7, leading to the accumulation of DeltaEx2p73 transcripts in HCC cells. CONCLUSIONS: This study provided a mechanism for the generation of protumorigenic DeltaEx2p73 during liver tumorigenesis, via activation of EGFR signaling by AR and c-Jun N-terminal kinase-1 activity, leading to inhibition of the splicing regulator Slu7.
Assuntos
Processamento Alternativo/efeitos dos fármacos , Carcinoma Hepatocelular/metabolismo , Proteínas de Ligação a DNA/metabolismo , Glicoproteínas/farmacologia , Peptídeos e Proteínas de Sinalização Intercelular/farmacologia , Neoplasias Hepáticas/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Anfirregulina , Carcinoma Hepatocelular/patologia , Técnicas de Cultura de Células , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/genética , Família de Proteínas EGF , Receptores ErbB/metabolismo , Humanos , Neoplasias Hepáticas/patologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Proteína Quinase 8 Ativada por Mitógeno/metabolismo , Proteínas Nucleares/genética , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteína Tumoral p73 , Proteínas Supressoras de Tumor/genéticaRESUMO
UNLABELLED: The hepatic wound-healing response to chronic noxious stimuli may lead to liver fibrosis, a condition characterized by excessive deposition of extracellular matrix. Fibrogenic cells, including hepatic stellate cells and myofibroblasts, are activated in response to a variety of cytokines, growth factors, and inflammatory mediators. The involvement of members of the epidermal growth factor family in this process has been suggested. Amphiregulin (AR) is an epidermal growth factor receptor (EGFR) ligand specifically induced upon liver injury. Here, we have addressed the in vivo role of AR in experimental liver fibrosis. To this end, liver fibrosis was induced in AR+/+ and AR-/- mice by chronic CCl(4) administration. Histological and molecular markers of hepatic fibrogenesis were measured. Additionally, the response of cultured human and mouse liver fibrogenic cells to AR was evaluated. We observed that AR was expressed in isolated Kupffer cells and liver fibrogenic cells in response to inflamatory stimuli and platelet-derived growth factor, respectively. We demonstrate that the expression of alpha-smooth muscle actin and collagen deposition were markedly reduced in AR-/- mice compared to AR+/+ animals. AR-/- mice also showed reduced expression of tissue inhibitor of metalloproteinases-1 and connective tissue growth factor, two genes that responded to AR treatment in cultured fibrogenic cells. AR also stimulated cell proliferation and exerted a potent antiapoptotic effect on isolated fibrogenic cells. CONCLUSION: These results indicate that among the different EGFR ligands, AR plays a specific role in liver fibrosis. AR may contribute to the expression of fibrogenic mediators, as well as to the growth and survival of fibrogenic cells. Additionally, our data lend further support to the role of the EGFR system in hepatic fibrogenesis.
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Receptores ErbB/metabolismo , Glicoproteínas/fisiologia , Peptídeos e Proteínas de Sinalização Intercelular/fisiologia , Cirrose Hepática/metabolismo , Fígado/metabolismo , Anfirregulina , Animais , Apoptose/fisiologia , Tetracloreto de Carbono , Linhagem Celular , Células Cultivadas , Modelos Animais de Doenças , Família de Proteínas EGF , Matriz Extracelular/metabolismo , Glicoproteínas/genética , Hepatócitos/metabolismo , Hepatócitos/patologia , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/genética , Ligantes , Fígado/patologia , Cirrose Hepática/induzido quimicamente , Cirrose Hepática/patologia , Masculino , Camundongos , Camundongos Knockout , Transdução de Sinais/fisiologiaRESUMO
Epidemiological studies have established that many tumours occur in association with persistent inflammation. One clear example of inflammation-related cancer is hepatocellular carcinoma (HCC). HCC slowly unfolds on a background of chronic inflammation triggered by exposure to infectious agents (hepatotropic viruses), toxic compounds (ethanol), or metabolic impairment. The molecular links that connect inflammation and cancer are not completely known, but evidence gathered over the past few years is beginning to define the precise mechanisms. A central role for cytokines such as interleukin-6 (IL-6) and IL-1 (alpha and beta) in liver cancer has been established in experimental models. Besides these inflammatory mediators, mounting evidence points to the dysregulation of specific growth and survival-related pathways in HCC development. Among them is the pathway governed by the epidermal growth factor receptor (EGFR), which can be bound and activated by a broad family of ligands. Of special relevance is the fact that the EGFR engages in extensive crosstalk with other signaling pathways, serving as a "signaling hub" for an increasing list of growth factors, cytokines, and inflammatory mediators. In this review, we summarize the most recent evidences supporting a role for the EGFR system in inflammation-related cell signaling, with special emphasis in liver inflammation and HCC. The molecular dissection of the pathways connecting the inflammatory reaction and neoplasia will facilitate the development of novel and more effective antitumor strategies.
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Receptores ErbB/fisiologia , Hepatite/fisiopatologia , Neoplasias Hepáticas/fisiopatologia , Animais , Carcinoma Hepatocelular/etiologia , Carcinoma Hepatocelular/fisiopatologia , Modelos Animais de Doenças , Humanos , Neoplasias Hepáticas/etiologia , Receptor Cross-Talk/fisiologia , Transdução de Sinais/fisiologiaRESUMO
Next-generation sequencing (NGS) allows in-depth analysis of tissue-specific transcriptomes, cistromes, and epigenomes for a better understanding of molecular events at different levels and has proved to be a valuable tool to encrypt the complex transcription networks in both physiological and pathological processes. The preparation of tissues such as the liver for the omics analysis remains to be challenging due to time-consuming and tedious steps. Here we describe a protocol to process frozen liver tissue samples for reduced representation bisulfite sequencing (RRBS), chromatin immunoprecipitation sequencing (ChIP-seq), and RNA sequencing (RNA-seq). This protocol allows further integrated omics analysis using minimum liver tissues to ensure best-quality data.
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Genômica , Fígado/metabolismo , Animais , Imunoprecipitação da Cromatina , Criopreservação , Genômica/métodos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Camundongos , Reprodutibilidade dos Testes , Análise de Sequência de DNA , TranscriptomaRESUMO
Pancreatic ductal adenocarcinoma, which represents 80% of pancreatic cancers, is mainly diagnosed when treatment with curative intent is not possible. Consequently, the overall five-year survival rate is extremely dismal-around 5% to 7%. In addition, pancreatic cancer is expected to become the second leading cause of cancer-related death by 2030. Therefore, advances in screening, prevention and treatment are urgently needed. Fortunately, a wide range of approaches could help shed light in this area. Beyond the use of cytological or histological samples focusing in diagnosis, a plethora of new approaches are currently being used for a deeper characterization of pancreatic ductal adenocarcinoma, including genetic, epigenetic, and/or proteo-transcriptomic techniques. Accordingly, the development of new analytical technologies using body fluids (blood, bile, urine, etc.) to analyze tumor derived molecules has become a priority in pancreatic ductal adenocarcinoma due to the hard accessibility to tumor samples. These types of technologies will lead us to improve the outcome of pancreatic ductal adenocarcinoma patients.
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Obesity triggers the development of non-alcoholic fatty liver disease (NAFLD), which involves alterations of regulatory transcription networks and epigenomes in hepatocytes. Here we demonstrate that G protein pathway suppressor 2 (GPS2), a subunit of the nuclear receptor corepressor (NCOR) and histone deacetylase 3 (HDAC3) complex, has a central role in these alterations and accelerates the progression of NAFLD towards non-alcoholic steatohepatitis (NASH). Hepatocyte-specific Gps2 knockout in mice alleviates the development of diet-induced steatosis and fibrosis and causes activation of lipid catabolic genes. Integrative cistrome, epigenome and transcriptome analysis identifies the lipid-sensing peroxisome proliferator-activated receptor α (PPARα, NR1C1) as a direct GPS2 target. Liver gene expression data from human patients reveal that Gps2 expression positively correlates with a NASH/fibrosis gene signature. Collectively, our data suggest that the GPS2-PPARα partnership in hepatocytes coordinates the progression of NAFLD in mice and in humans and thus might be of therapeutic interest.
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Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Fígado/patologia , Hepatopatia Gordurosa não Alcoólica/patologia , PPAR alfa/metabolismo , Animais , Biópsia , Conjuntos de Dados como Assunto , Dieta Hiperlipídica/efeitos adversos , Modelos Animais de Doenças , Progressão da Doença , Epigênese Genética , Fibrose , Células HEK293 , Hepatócitos/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Metabolismo dos Lipídeos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/genética , Hepatopatia Gordurosa não Alcoólica/metabolismo , PPAR alfa/genéticaRESUMO
Non-alcoholic fatty liver disease (NAFLD) is a very common indication for liver transplantation. How fat-rich diets promote progression from fatty liver to more damaging inflammatory and fibrotic stages is poorly understood. Here, we show that disrupting phosphorylation at Ser196 (S196A) in the liver X receptor alpha (LXRα, NR1H3) retards NAFLD progression in mice on a high-fat-high-cholesterol diet. Mechanistically, this is explained by key histone acetylation (H3K27) and transcriptional changes in pro-fibrotic and pro-inflammatory genes. Furthermore, S196A-LXRα expression reveals the regulation of novel diet-specific LXRα-responsive genes, including the induction of Ces1f, implicated in the breakdown of hepatic lipids. This involves induced H3K27 acetylation and altered LXR and TBLR1 cofactor occupancy at the Ces1f gene in S196A fatty livers. Overall, impaired Ser196-LXRα phosphorylation acts as a novel nutritional molecular sensor that profoundly alters the hepatic H3K27 acetylome and transcriptome during NAFLD progression placing LXRα phosphorylation as an alternative anti-inflammatory or anti-fibrotic therapeutic target.
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Gorduras na Dieta/efeitos adversos , Receptores X do Fígado/metabolismo , Mutação de Sentido Incorreto , Substituição de Aminoácidos , Animais , Gorduras na Dieta/farmacologia , Receptores X do Fígado/genética , Camundongos , Camundongos Transgênicos , Hepatopatia Gordurosa não Alcoólica/induzido quimicamente , Hepatopatia Gordurosa não Alcoólica/genética , Hepatopatia Gordurosa não Alcoólica/patologia , Fosforilação/efeitos dos fármacos , Fosforilação/genéticaRESUMO
Humans with obesity differ in their susceptibility to developing insulin resistance and type 2 diabetes (T2D). This variation may relate to the extent of adipose tissue (AT) inflammation that develops as their obesity progresses. The state of macrophage activation has a central role in determining the degree of AT inflammation and thus its dysfunction, and these states are driven by epigenomic alterations linked to gene expression. The underlying mechanisms that regulate these alterations, however, are poorly defined. Here we demonstrate that a co-repressor complex containing G protein pathway suppressor 2 (GPS2) crucially controls the macrophage epigenome during activation by metabolic stress. The study of AT from humans with and without obesity revealed correlations between reduced GPS2 expression in macrophages, elevated systemic and AT inflammation, and diabetic status. The causality of this relationship was confirmed by using macrophage-specific Gps2-knockout (KO) mice, in which inappropriate co-repressor complex function caused enhancer activation, pro-inflammatory gene expression and hypersensitivity toward metabolic-stress signals. By contrast, transplantation of GPS2-overexpressing bone marrow into two mouse models of obesity (ob/ob and diet-induced obesity) reduced inflammation and improved insulin sensitivity. Thus, our data reveal a potentially reversible disease mechanism that links co-repressor-dependent epigenomic alterations in macrophages to AT inflammation and the development of T2D.
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Tecido Adiposo/metabolismo , Diabetes Mellitus Tipo 2/genética , Resistência à Insulina/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Macrófagos/metabolismo , Obesidade/genética , Tecido Adiposo/citologia , Tecido Adiposo/imunologia , Adulto , Animais , Western Blotting , Transplante de Medula Óssea , Diabetes Mellitus Tipo 2/imunologia , Diabetes Mellitus Tipo 2/metabolismo , Dieta Hiperlipídica , Feminino , Citometria de Fluxo , Expressão Gênica , Humanos , Imuno-Histoquímica , Inflamação/genética , Inflamação/imunologia , Resistência à Insulina/imunologia , Peptídeos e Proteínas de Sinalização Intracelular/imunologia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Knockout , Camundongos Obesos , Pessoa de Meia-Idade , Obesidade/imunologia , Obesidade/metabolismo , Células RAW 264.7 , RNA Interferente Pequeno , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Estresse FisiológicoRESUMO
A precise equilibrium between cellular differentiation and proliferation is fundamental for tissue homeostasis. Maintaining this balance is particularly important for the liver, a highly differentiated organ with systemic metabolic functions that is endowed with unparalleled regenerative potential. Carcinogenesis in the liver develops as the result of hepatocellular de-differentiation and uncontrolled proliferation. Here, we identified SLU7, which encodes a pre-mRNA splicing regulator that is inhibited in hepatocarcinoma, as a pivotal gene for hepatocellular homeostasis. SLU7 knockdown in human liver cells and mouse liver resulted in profound changes in pre-mRNA splicing and gene expression, leading to impaired glucose and lipid metabolism, refractoriness to key metabolic hormones, and reversion to a fetal-like gene expression pattern. Additionally, loss of SLU7 also increased hepatocellular proliferation and induced a switch to a tumor-like glycolytic phenotype. Slu7 governed the splicing and/or expression of multiple genes essential for hepatocellular differentiation, including serine/arginine-rich splicing factor 3 (Srsf3) and hepatocyte nuclear factor 4α (Hnf4α), and was critical for cAMP-regulated gene transcription. Together, out data indicate that SLU7 is central regulator of hepatocyte identity and quiescence.
Assuntos
Fígado/metabolismo , Splicing de RNA , Ribonucleoproteínas Nucleares Pequenas/genética , Ribonucleoproteínas Nucleares Pequenas/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Animais , Carcinoma Hepatocelular/etiologia , Diferenciação Celular , Expressão Gênica , Técnicas de Silenciamento de Genes , Glucose/metabolismo , Células Hep G2 , Hepatócitos/citologia , Hepatócitos/metabolismo , Homeostase , Humanos , Metabolismo dos Lipídeos , Neoplasias Hepáticas/etiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fatores de Processamento de RNA , Ribonucleoproteínas Nucleares Pequenas/antagonistas & inibidores , Fatores de Transcrição/antagonistas & inibidoresRESUMO
Hepatocarcinogenesis is a complex multistep process in which many different molecular pathways have been implicated. Hepatocellular carcinoma (HCC) is refractory to conventional chemotherapeutic agents, and the new targeted therapies are meeting with limited success. Interreceptor crosstalk and the positive feedback between different signaling systems are emerging as mechanisms of targeted therapy resistance. The identification of such interactions is therefore of particular relevance to improve therapeutic efficacy. Among the different signaling pathways activated in hepatocarcinogenesis the epidermal growth factor receptor (EGFR) system plays a prominent role, being recognized as a "signaling hub" where different extracellular growth and survival signals converge. EGFR can be transactivated in response to multiple heterologous ligands through the physical interaction with multiple receptors, the activity of intracellular kinases or the shedding of EGFR-ligands. In this article we review the crosstalk between the EGFR and other signaling pathways that could be relevant to liver cancer development and treatment.
RESUMO
Pre-mRNA splicing is an essential step in the process of gene expression in eukaryotes and consists of the removal of introns and the linking of exons to generate mature mRNAs. This is a highly regulated mechanism that allows the alternative usage of exons, the retention of intronic sequences and the generation of exonic sequences of variable length. Most human genes undergo splicing events, and disruptions of this process have been associated with a variety of diseases, including cancer. Hepatocellular carcinoma (HCC) is a molecularly heterogeneous type of tumor that usually develops in a cirrhotic liver. Alterations in pre-mRNA splicing of some genes have been observed in liver cancer, and although still scarce, the available data suggest that splicing defects may have a role in hepatocarcinogenesis. Here we briefly review the general mechanisms that regulate pre-mRNA splicing, and discuss some examples that illustrate how this process is impaired in liver tumorigenesis, and may contribute to HCC development. We believe that a more thorough examination of pre-mRNA splicing is still needed to accurately draw the molecular portrait of liver cancer. This will surely contribute to a better understanding of the disease and to the development of new effective therapies.