title: Genome-wide analysis of histone H3 lysine 27 trimethylation by ChIP-chip in gastric cancer patients.
abstract: BACKGROUND
  Trimethylation of histone H3 lysine 27 (H3K27me3) is a posttranslational modification that is highly correlated with genomic silencing. In gastric cancer (GC), global and gene-specific DNA methylation changes have been demonstrated to occur. However, to date, our understanding of the alterations in H3K27me3 in GC is incomplete. This study aimed to investigate the variations in H3K27me3 in CpG island regions between gastric cancerous and matched non-cancerous tissues.
  
  
  METHODS
  H3K27me3 variations were analyzed in eight pairs of GC and adjacent normal tissues, from eight GC patients, using a chromatin immunoprecipitation linked to the microarray (ChIP-chip) approach. ChIP-real time PCR was used to validate the microrray results. In addition, DNA methylation status also was further analyzed by methyl-DNA immunoprecipitation quantitative PCR.
  
  
  RESULTS
  One hundred twenty-eight (119 increased and 9 decreased H3K27me3) genes displaying significant H3K27me3 differences were found between GC and adjacent normal tissues. The results of ChIP-real time PCR coincided well with those of microarray. Aberrant DNA methylation can also be found on selected randomly positive genes (MMP15, UNC5B, SHH, AFF3, and RB1).
  
  
  CONCLUSIONS
  Our study indicates that there are significant alterations of H3K27me3 in gastric cancerous tissues, which may help clarify the molecular mechanisms involved in the pathogenesis of GC. Such novel findings show the significance of H3K27me3 as a potential biomarker or promising target for epigenetic-based GC therapies.
authors.affiliation: The Second Clinical Medical College, Jinan University, Guangdong, China. zhanglichangde@163.com
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Keli
authors.initials: K
authors.lastname: Zhong
authors.forename: Yong
authors.initials: Y
authors.lastname: Dai
authors.forename: Hanxin
authors.initials: H
authors.lastname: Zhou
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics*; D000368:Aged; D047369:Chromatin Immunoprecipitation / Q000379:methods; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D005260:Female; D020868:Gene Silencing; D016678:Genome; D006657:Histones / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction / Q000379:methods; D011499:Protein Processing, Post-Translational; D013274:Stomach Neoplasms / Q000235:genetics*
chemical_list: D006657:Histones