title: [Histone H3 lysine 9 methylation is associated with the expression of hMLH1 and DNA methylation in gastric cancer cells].
abstract: OBJECTIVE
  To identify the association of his tone H3 lysine 9 (H3-K9) methylation with DNA methylation and the expression of the mismatch repair gene hMLH1 in human gastric cancer cells.
  
  
  METHODS
  Gastric cancer cells of the lines BGC-823 and MGC-803 were cultured and treated with 5-Aza-2'-deoxycytidine (5-Aza-dC), a demethylation agent, for 72 hour. Chromatin immunoprecipitation (ChIP) assay was used to assess the status of histone H3 lysine 9 methylation in the promoter regions of hMLH1 gene. Methylation-specific PCR (MSP) was used to evaluate the effect of 5-Aza-dC on DNA methylation status. RT-PCR was used to examine the hMLH1 gene expression.
  
  
  RESULTS
  In the MGC-803 cells, silenced hMLH1 gene was characterized by DNA methylation and histone H3-K9 hypermethylation; 5-Aza-dC demethylated the DNA and reduced the histone H3-K9 methylation at silenced loci and resulted in reactivation of hMLH1 gene therein. Contrary to the MGC-803 cells, BGC-823 cells expressed hMLH1 gene with DNA demethylation and histone H3-K9 hypomethylation; and 5-Aza-dC had no effects on the gene expression, DNA methylation, and histone H3-K9 methylation therein.
  
  
  CONCLUSIONS
  Hypermethylation of DNA in the promoter region is related to transcriptional silencing of hMLH1 gene. Histone H3-K9 methylation in different regions of the promoter studied correlates with DNA methylation status of hMLH1 gene in gastric cancer cells. Alteration of DNA methylation affects histone H3-K9 methylation. 5-Aza-dC can control hMLH1 expression, DNA methylation, and histone H3-K9 methylation in the promoter.
authors.affiliation: Department of Surgical Oncology, Department of General Surgery, First Affiliated Hospital, China Medical University, Shenyang 110001, China.
authors.forename: Chun-Feng
authors.initials: CF
authors.lastname: Meng
authors.forename: Xin-Jiang
authors.initials: XJ
authors.lastname: Zhu
authors.forename: Guo
authors.initials: G
authors.lastname: Peng
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics*; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D019175:DNA Methylation; D053843:DNA Mismatch Repair; D015870:Gene Expression; D016147:Genes, Tumor Suppressor; D006657:Histones / Q000235:genetics*; D006801:Humans; D000070957:MutL Protein Homolog 1; D009687:Nuclear Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D006657:Histones; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D000070957:MutL Protein Homolog 1; D001374:Azacitidine