ABSTRACT
DNA methylation, histone modifications, and the chromatin structure are profoundly altered in human cancers. The silencing of cancer-related genes by these epigenetic regulators is recognized as a key mechanism in tumor formation. Recent findings revealed that DNA methylation and histone modifications appear to be linked to each other. However, it is not clearly understood how the formation of histone modifications may affect DNA methylation and which genes are relevantly involved with tumor formation. The presence of histone modifications does not always link to DNA methylation in human cancers, which suggests that another factor is required to connect these two epigenetic mechanisms. In this review, examples of studies that demonstrated the relationship between histone modifications and DNA methylation in human cancers are presented and the potential implications of these epigenetic mechanisms in human neoplasia are discussed.
Subject(s)
Humans , DNA Methylation/physiology , Epigenesis, Genetic/physiology , Histone-Lysine N-Methyltransferase/metabolism , Histones/metabolism , Models, Biological , Neoplasms/geneticsABSTRACT
DNA methylation, histone modifications, and the chromatin structure are profoundly altered in human cancers. The silencing of cancer-related genes by these epigenetic regulators is recognized as a key mechanism in tumor formation. Recent findings revealed that DNA methylation and histone modifications appear to be linked to each other. However, it is not clearly understood how the formation of histone modifications may affect DNA methylation and which genes are relevantly involved with tumor formation. The presence of histone modifications does not always link to DNA methylation in human cancers, which suggests that another factor is required to connect these two epigenetic mechanisms. In this review, examples of studies that demonstrated the relationship between histone modifications and DNA methylation in human cancers are presented and the potential implications of these epigenetic mechanisms in human neoplasia are discussed.
Subject(s)
Humans , DNA Methylation/physiology , Epigenesis, Genetic/physiology , Histone-Lysine N-Methyltransferase/metabolism , Histones/metabolism , Models, Biological , Neoplasms/geneticsABSTRACT
Elemental carbon (EC) and organic carbon (OC) in PM2.5 were measured simultaneously at the campus of Peking University from January 2006 to April 2007 by two common used methodologies. One is quartz filter sampling followed by off-line SUNSET Lab EC/OC analyzer and the other is SUNSET in-situ on-line EC/OC analyzer. The comparison shows significant differences on OC measurements between the two methods. The results by filter sampling off-line analysis were as twice high as those by in-situ on-line method. The volatile organic carbons (VOCs) adsorbed by quartz filter led to considerable positive error of OC. The use of parallel plate organic denuder can eliminate such error but cause the evaporation of semi-volatile organic carbon on the filter which induces another negative error of OC, about 10%. The improved method of filter sampling off-line analysis using both parallel plate organic denuder and backup filter has a good agreement with in-situ online measurement.
