Asunto(s)
Metilación de ADN , ADN/química , ADN/genética , Análisis de Secuencia de ADN/métodos , Secuencia de Bases , Sitios de Unión , Cromatografía de Afinidad/métodos , Islas de CpG , Proteínas de Unión al ADN/metabolismo , Genoma Humano , Humanos , Datos de Secuencia Molecular , Reproducibilidad de los Resultados , SulfitosRESUMEN
CpG island methylation is an important mechanism in gene silencing and is a key epigenetic event in cancer development. As yet, the number and identities of the genes that are inactivated in cancer cells has not been determined. In order to address this issue, we have performed a comprehensive isolation of CpG islands that are methylated in human lung adenocarcinomas. We have isolated approximately 200 CpG islands that are methylated in tumor DNA including those of known tumor-associated genes such as the HOXA5 gene. As the library contains the CpG islands of a number of known tumor suppressor genes it is highly likely that additional, previously unidentified tumor suppressor genes, will be present. On average, 1-2% of CpG islands were methylated specifically in tumors although this figure differed greatly between patients. This study provides an important resource in the search for genes inactivated in tumors and for the investigation of epigenetic dysregulation of gene expression by CpG island methylation.
Asunto(s)
Adenocarcinoma/genética , Islas de CpG/genética , Metilación de ADN , Genes Supresores de Tumor , Neoplasias Pulmonares/genética , Anciano , Biblioteca Genómica , Humanos , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transcripción GenéticaRESUMEN
CpG island methylation results in the silencing of the associated gene and is an important step in tumorigenesis. Following a comprehensive isolation of CpG islands that were methylated in human lung adenocarcinoma, we found that in cancer cells de novo CpG island methylation generally occurred in a sporadic manner. However, some methylated CpG islands appeared to cluster in discrete chromosomal regions. In this study, we have investigated the methylation status of CpG islands located at such chromosomal loci. We have found that many CpG islands at the HOXA and HOXD loci were methylated in human lung adenocarcinoma. The de novo methylation of these CpG islands was also observed in patient's DNA from noncancerous portions of lung tissue. These results indicate the presence of specific chromosomal regions that are susceptible to de novo methylation.
