RESUMO
A histone acetyltransferase Tat-interacting protein 60 kDa (Tip60) regulates the DNA damage response by acetylating histone and remodeling chromatin. In addition to histone acetyltransferase activity, Tip60 is known to regulate a variety of cellular functions, including gene expression, DNA damage response, cell migration and apoptosis. Lower expression of Tip60 is observed in lymphomas, melanomas, breast, colon, and lung cancer. It is widely accepted that Tip60 functions as a tumor suppressor. However, a role of Tip60 in gliomas still remains unclear. In this study, we investigated the role of Tip60 in the malignant behavior of human gliomas. By quantitative RT-PCR analysis using fresh human brain tumor tissues from 55 patients, we found that lower Tip60 expression and higher membrane-type 1 matrix metalloproteinase (MT1-MMP) expression are associated with advanced tumor grade in glioma tissues. Knockdown of Tip60 in glioblastoma cells promoted cell adhesion, spreading and MT1-MMP transcription and thereby invasion, which was suppressed by inhibition of MT1-MMP and nuclear factor-kappa B (NF-κB) activity. We demonstrate for the first time that tumor suppressor Tip60 down-regulates cell adhesion and MT1-MMP expression and thereby invasion of glioblastoma cells by suppressing NF-κB pathway.
Assuntos
Neoplasias Encefálicas/patologia , Regulação Neoplásica da Expressão Gênica/fisiologia , Glioblastoma/patologia , Histona Acetiltransferases/biossíntese , Metaloproteinase 14 da Matriz/biossíntese , Adesão Celular/genética , Movimento Celular/genética , Regulação para Baixo , Imunofluorescência , Técnicas de Silenciamento de Genes , Histona Acetiltransferases/genética , Humanos , Immunoblotting , Lisina Acetiltransferase 5 , Metaloproteinase 14 da Matriz/genética , NF-kappa B/metabolismo , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , RNA Interferente Pequeno , Reação em Cadeia da Polimerase em Tempo Real , Transcrição GênicaRESUMO
Vinculin regulates a variety of cellular functions partly through stabilization of tumor suppressor PTEN. In order to study the role of vinculin in tumor progression other than PTEN stabilization, vinculin was knocked down in PTEN-deficient squamous cell carcinoma HSC-4 cells. Knockdown of vinculin induced phenotypical change by reducing cell-cell and cell-extracellular matrix adhesions, and enhanced MT1-MMP expression at transcription level and subsequent cell migration. Up-regulation of MT1-MMP transcription by vinculin knockdown was abrogated by ERK inhibition. These results suggest that vinculin negatively regulates malignant phenotype of tumor cells including MT1-MMP transcription through MEK/ERK pathway.
Assuntos
Regulação Enzimológica da Expressão Gênica , Sistema de Sinalização das MAP Quinases , Metaloproteinase 14 da Matriz/metabolismo , Vinculina/metabolismo , Comunicação Celular , Linhagem Celular Tumoral , Movimento Celular , Colágeno/metabolismo , Ativação Enzimática , Matriz Extracelular/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Fenótipo , Prognóstico , RNA Interferente Pequeno/metabolismo , Transcrição GênicaRESUMO
Fibronectin matrix formation requires the increased cytoskeletal tension generated by cadherin adhesions, and is suppressed by membrane-type 1 matrix metalloproteinase (MT1-MMP). In a co-culture of Rat1 fibroblasts and MT1-MMP-silenced HT1080 cells, fibronectin fibrils extended from Rat1 to cell-matrix adhesions in HT1080 cells, and N-cadherin adhesions were formed between Rat1 and HT1080 cells. In control HT1080 cells contacting with Rat1 fibroblasts, cell-matrix adhesions were formed in the side away from Rat1 fibroblasts, and fibronectin assembly and N-cadherin adhesions were not formed. The role of N-cadherin adhesions in fibronectin matrix formation was studied using MT1-MMP-silenced HT1080 cells. MT1-MMP knockdown promoted fibronectin matrix assembly and N-cadherin adhesions in HT1080 cells, which was abrogated by double knockdown with either integrin ß1 or fibronectin. Conversely, inhibition of N-cadherin adhesions by its knockdown or treatment with its neutralizing antibody suppressed fibronectin matrix formation in MT1-MMP-silenced cells. These results demonstrate that fibronectin assembly initiated by MT1-MMP knockdown results in increase of N-cadherin adhesions, which are prerequisite for further fibronectin matrix formation.
Assuntos
Caderinas/metabolismo , Fibronectinas/metabolismo , Metaloproteinase 14 da Matriz/metabolismo , Linhagem Celular , Linhagem Celular Tumoral , Junções Célula-Matriz , Técnicas de Cocultura , Técnicas de Silenciamento de Genes , Humanos , Metaloproteinase 14 da Matriz/genéticaRESUMO
Claudin-7 belongs to the claudin family, which consists of 24 subtypes of essential tight junction (TJ) integral membrane proteins with molecular weights of 20-27 kDa. We investigated the interrelationship between clinicopathological findings and claudin-7 expression in oral squamous cell carcinoma (OSCC). Using immunohistochemical techniques to examine the expression levels of claudin-7 in 67 cases of OSCC, claudin-7 expression was detected in 35 (52.2%) of the 67 cases. We also compared the clinicopathological features of the OSCC cases with claudin-7 expression levels. Moreover, six cell lines with various invasive properties were investigated in vitro to compare mRNA and protein levels of claudin-7 using reverse transcription-polymerase chain reaction (RT-PCR) and the western blotting method. Decreased claudin-7 expression correlated significantly with T-category (p<0.05), lymph node metastasis (p<0.01), and mode of invasion (p<0.001). Patients with positive claudin-7 expression had a significantly better prognosis (p<0.05). Claudin-7 protein and mRNA levels were lower in the HOC313 and TSU cells, which have higher invasive potentials compared with other cell lines. These results suggest that loss of claudin-7 expression is associated closely with invasion and lymph metastasis and is an unfavorable prognostic factor in patients with OSCC.