RESUMO
Fibrosis is a condition characterized by the excessive accumulation of extracellular matrix proteins in tissues, leading to organ dysfunction and failure. Recent studies have identified EP300, a histone acetyltransferase, as a crucial regulator of the epigenetic changes that contribute to fibrosis. In fact, EP300-mediated acetylation of histones alters global chromatin structure and gene expression, promoting the development and progression of fibrosis. Here, we review the role of EP300-mediated epigenetic regulation in multi-organ fibrosis and its potential as a therapeutic target. We discuss the preclinical evidence that suggests that EP300 inhibition can attenuate fibrosis-related molecular processes, including extracellular matrix deposition, inflammation, and epithelial-to-mesenchymal transition. We also highlight the contributions of small molecule inhibitors and gene therapy approaches targeting EP300 as novel therapies against fibrosis.
Assuntos
Epigênese Genética , Histonas , Humanos , Fibrose , Histonas/metabolismo , Matriz Extracelular/metabolismo , Histona Acetiltransferases/metabolismo , Proteína p300 Associada a E1A/genética , Proteína p300 Associada a E1A/metabolismoRESUMO
Autophagy is an evolutionarily preserved degradation process of cytoplasmic cellular constituents, which participates in cell response to disease. We previously characterized VMP1 (Vacuole Membrane Protein 1) as an essential autophagy related protein that mediates autophagy in pancreatic diseases. We also demonstrated that VMP1-mediated autophagy is induced by HIF-1A (hypoxia inducible factor 1 subunit alpha) in colon-cancer tumor cell lines, conferring resistance to photodynamic treatment. Here we identify a new molecular pathway, mediated by VMP1, by which gemcitabine is able to trigger autophagy in human pancreatic tumor cell lines. We demonstrated that gemcitabine requires the VMP1 expression to induce autophagy in the highly resistant pancreatic cancer cells PANC-1 and MIAPaCa-2 that carry activated KRAS. E2F1 is a transcription factor that is regulated by the retinoblastoma pathway. We found that E2F1 is an effector of gemcitabine-induced autophagy and regulates the expression and promoter activity of VMP1. Chromatin immunoprecipitation assays demonstrated that E2F1 binds to the VMP1 promoter in PANC-1 cells. We have also identified the histone acetyltransferase EP300 as a modulator of VMP1 promoter activity. Our data showed that the E2F1-EP300 activator/co-activator complex is part of the regulatory pathway controlling the expression and promoter activity of VMP1 triggered by gemcitabine in PANC-1 cells. Finally, we found that neither VMP1 nor E2F1 are induced by gemcitabine treatment in BxPC-3 cells, which do not carry oncogenic KRAS and are sensitive to chemotherapy. In conclusion, we have identified the E2F1-EP300-VMP1 pathway that mediates gemcitabine-induced autophagy in pancreatic cancer cells. These results strongly support that VMP1-mediated autophagy may integrate the complex network of events involved in pancreatic ductal adenocarcinoma chemo-resistance. Our experimental findings point at E2F1 and VMP1 as novel potential therapeutic targets in precise treatment strategies for pancreatic cancer.
Assuntos
Autofagia , Desoxicitidina/análogos & derivados , Proteína p300 Associada a E1A/metabolismo , Fator de Transcrição E2F1/metabolismo , Proteínas de Membrana/metabolismo , Neoplasias Pancreáticas/patologia , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Antimetabólitos Antineoplásicos/farmacologia , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Desoxicitidina/farmacologia , Proteína p300 Associada a E1A/genética , Fator de Transcrição E2F1/genética , Regulação Neoplásica da Expressão Gênica , Humanos , Proteínas de Membrana/genética , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/genética , Células Tumorais Cultivadas , GencitabinaRESUMO
Sarco(endo)plasmic reticulum Ca2+-ATPases (SERCA) expression is reduced or absent in several types of cancer and cancer cell lines; however, their expression and regulation in hepatocellular carcinoma (HCC) are unknown. Histone deacetylase inhibitors (HDACi) increase SERCA3 mRNA expression in gastric and breast cancer cell lines by increasing H3K9ac and binding of Sp1 and Sp3 transcription factors to the promoter; however, the molecular mechanism is not fully understood. Our results show that ATP2A3 (SERCA3) gene expression is decreased in human HCC samples and rat HCC AS-30D cells compared to normal liver, and HCC patients with high expression of ATP2A3 had longer overall survival than those with low expression. Sodium butyrate (NaB) and trichostatin A (TSA) increase SERCA3 mRNA expression in AS-30D cells, whereas SERCA2b mRNA expression did not change. NaB and TSA increase H3K9ac and H3K27ac in two ATP2A3 promoter regions. Besides, NaB treated cells increased Sp1 and Sp3 occupancy at ATP2A3 promoter; whereas TSA treated cells showed increased p300 levels at ATP2A3 promoter. Inhibition of p300 by C646, a specific inhibitor, mitigates SERCA3 mRNA induction by TSA, and reduces more than 70% of basal SERCA3 mRNA expression, suggesting that p300 is important for ATP2A3 gene transcription in AS-30D cells. Moreover, inhibition of p300 decreases H3K9ac in TSA treated cells. Our results provide evidence of decreased SERCA3 expression in human HCC samples and rat AS-30D cells and a correlation of SERCA3 expression with overall survival in HCC patients. Also, reveal new insights in SERCA3 transcriptional regulation mediated by HDACi.
Assuntos
Carcinoma Hepatocelular/metabolismo , Proteína p300 Associada a E1A/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Neoplasias Hepáticas/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/biossíntese , Animais , Ácido Butírico/farmacologia , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/genética , Expressão Gênica/efeitos dos fármacos , Histonas/genética , Histonas/metabolismo , Humanos , Ácidos Hidroxâmicos/farmacologia , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/genética , Regiões Promotoras Genéticas , Ratos , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/genética , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Células Tumorais CultivadasRESUMO
OBJECTS: The protein 300 (p300) and p300/CBP-binding protein-associated factor (PCAF) are enzymes with histone acetyltransferase (HAT) activity, a function that can become deregulated in different tumors and affect biological responses. METHODS: Due to the lack of information on the deregulation of these HATs in pediatric tumors, this study evaluated the expression of both the mRNA and proteins of p300 and PCAF in 54 samples of pediatric astrocytomas embedded in paraffin. RESULTS: PCAF was not expressed in normal brain tissue. In grade I tumors, the expression of p300 (1.1 ± 0.1) and PCAF (1.2 ± 0.11) was greater than those observed in grade III tumors: 0.72 ± 0.15 for p300 and 0.55 ± 0.11 for PCAF, and grade IV tumors: 0.74 ± 0.13 for p300 and 0.55 ± 0.13 for PCAF (p < 0.05). Immunohistochemical staining revealed the same tendency towards a decrease in the expression of the protein as the degree of clinical severity increased. Patients with recurrent grades I, III, and IV tumors had the highest levels of PCAF, compared to those who showed no recurrence (p < 0.05). CONCLUSIONS: This work describes and confirms that these HATs play important roles in regulating genes and in the biological behavior of pediatric astrocytomas.
Assuntos
Astrocitoma/genética , Neoplasias Encefálicas/genética , Proteína p300 Associada a E1A/genética , Recidiva Local de Neoplasia/genética , RNA Mensageiro/metabolismo , Fatores de Transcrição de p300-CBP/genética , Astrocitoma/metabolismo , Astrocitoma/patologia , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Criança , Proteína p300 Associada a E1A/metabolismo , Humanos , Imuno-Histoquímica , Gradação de Tumores , Recidiva Local de Neoplasia/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Fatores de Transcrição de p300-CBP/metabolismoRESUMO
Hypoxia has emerged as a key determinant of osteogenesis. HIF-1α is the transcription factor mediating hypoxia responses that include induction of VEGF and related bone induction. Inflammatory signals antagonize bone repair via the NF-κB pathway. The present investigation explored the functional relationship of hypoxia (HIF-1α function) and inflammatory signaling (NF-κB) in stem like and osteoprogenitor cell lines. The potential interaction between HIF-1α and NF-κB signaling was explored by co-transfection studies in hFOB with p65, HIF-1α and 9x-HRE-luc or HIF-1α target genes reporter plasmids. Nuclear cross-talk was directly tested using the mammalian Gal4/VP16 two-hybrid, and confirmed by co-immunoprecipitation/western blotting assays. The results show that inflammatory stimulation (TNF-α treatment) causes a marked inhibition of HIF-1α function at the HRE in all cell lines studied. Also, co-transfection with p65 expression vector leads to reduced hVEGFp transcription after DFO-induced hypoxia. However, TNF-α treatment had little effect on HIF-1α mRNA levels. The functional interaction of Gal4-HIF-1α and VP16-p300 fusion proteins is effectively blocked by expression of p65 in a dose dependent manner. It was concluded that NF-κB-mediated inflammatory signaling is able to block HIF-1α transactivation at HRE-encoding genes by direct competition for p300 binding at the promoter. Inflammation may influence the stem cell niche and tissue regeneration by influencing cellular responses to hypoxia.
Assuntos
Proteína p300 Associada a E1A/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , NF-kappa B/metabolismo , Osteogênese/genética , Ativação Transcricional , Fator A de Crescimento do Endotélio Vascular/genética , Hipóxia Celular/genética , Linhagem Celular , Expressão Gênica , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Inflamação/genética , NF-kappa B/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Regiões Promotoras Genéticas , RNA Mensageiro/metabolismo , Fator de Transcrição RelA/genética , Fator de Transcrição RelA/metabolismoRESUMO
It has been recently suggested that p300 cytoplasmic redistribution and degradation are important for controlling the availability and activity of the protein as a transcriptional coactivator. As a step towards determining the functional relevance of p300 intracellular redistribution in mammary cancer, we aimed at studying p300 localization in two different animal models of mammary carcinoma as well as in human primary breast carcinoma samples. Analysis of p300 protein levels showed stronger expression in tumor epithelia than in normal mammary gland. Cytoplasmic localization of p300 was observed in malignant cells. Furthermore, cytoplasmic p300 was found in tumor epithelia whereas nuclear localization was observed in normal mammary glands in both animal models and in non-malignant adjacent areas of human breast cancer specimens. Interestingly, proteasomal inhibition induced p300 redistribution to perinuclear inclusion bodies in tumor but not in normal mammary gland-derived cells. These inclusions were confirmed to be aggresomes by doing immunofluorescence for ubiquitin, vimentin and 20S proteasomal subunit. Taken together, these findings show that both the localization of p300 and the recruitment to aggresomes differ between mammary tumors and normal mammary glands, and suggest that the formation of these inclusions could be a potential target for therapeutic intervention.
Assuntos
Neoplasias da Mama/metabolismo , Mama/metabolismo , Proteína p300 Associada a E1A/metabolismo , Adenocarcinoma/genética , Animais , Western Blotting , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Citoplasma/metabolismo , Citoplasma/patologia , Proteína p300 Associada a E1A/genética , Feminino , Humanos , Imuno-Histoquímica , Corpos de Inclusão/metabolismo , Corpos de Inclusão/patologia , Glândulas Mamárias Animais/metabolismo , Neoplasias Mamárias Animais/genética , Camundongos , Camundongos Transgênicos , Complexo de Endopeptidases do Proteassoma/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Valores de Referência , Transcrição Gênica , Ubiquitina/metabolismo , Vimentina/metabolismoRESUMO
Interferon-gamma/transforming growth factor-beta (IFN-gamma/TGF-beta) pathways have opposite effects on diverse cellular functions. However, little is known about interactions between IFN-alpha/TGF-beta. In previous studies, we showed that IFN-alpha2b increases TGF-beta(1) production and secretion in hepatocytes from preneoplastic rat livers. Here, the interaction between IFN-alpha/TGF-beta(1) pathways was explored. We observed a positive cross-talk between IFN-alpha and TGF-beta(1) signaling, with activation of both pathways. p300 protein levels in hepatocytes from preneoplastic livers were enough to interact with both activated Stat1 and Smad2/3. Besides, Smad7 was not directly related with TGF-beta(1) and IFN-alpha signals. Interestingly, we reported the novel finding that the autocrine TGF-beta(1) up-regulates TGF-betaRII at protein and mRNA levels. In conclusion, the intracellular signals triggered by IFN-alpha2b and by autocrine TGF-beta(1) are integrated at the nuclear level, where activated Stat1 and Smad2/3 are capable of interact with p300, present in no restrictive cellular amounts.
Assuntos
Regulação da Expressão Gênica , Hepatócitos/metabolismo , Interferon-alfa/metabolismo , Neoplasias Hepáticas Experimentais/metabolismo , Lesões Pré-Cancerosas/metabolismo , Transdução de Sinais , Fator de Crescimento Transformador beta1/metabolismo , Animais , Núcleo Celular/metabolismo , Células Cultivadas , Proteína p300 Associada a E1A/metabolismo , Interferon alfa-2 , Fígado/citologia , Fígado/metabolismo , Fígado/fisiopatologia , Neoplasias Hepáticas Experimentais/fisiopatologia , Masculino , Lesões Pré-Cancerosas/fisiopatologia , Ratos , Ratos Wistar , Proteínas Recombinantes , Fator de Transcrição STAT1/metabolismo , Proteína Smad2/metabolismo , Proteína Smad3/metabolismoRESUMO
CCL5 is a key in limiting mycobacterial infection. Although NF-kappaB has been implicated, signaling cascades involved in CCL5 production by epithelial cells following infection with Mycobacterium bovis BCG are still not defined. Here we show that using pharmacological inhibition of sphingosine kinase (SPK), striking inhibition of M. bovis BCG-induced CCL5 protein was observed. Phosphatidylinositol 3-kinase (PI3K) and Akt were also important for CCL5 production by epithelial cells infected with M. bovis BCG. Moreover, there was increased activation of PI3K, IKK/alphabeta and NF-kappaB in A549 cells infected with M. bovis BCG. Importantly, the PI3K activation was dependent on SPK. Finally, M. bovis BCG increases the recruitment of p300 with NF-kappaB in A549 cells. Together, these studies are the first to show that M. bovis BCG-induced CCL5 secretion is dependent on the SPK/PI3K/Akt/NF-kappaB and p300 signaling pathway. The regulatory pathways of M. bovis BCG-induced CCL5 production can potentially be exploited therapeutically.