title: Decreased expression of retinoblastoma protein-interacting zinc-finger gene 1 in human esophageal squamous cell cancer by DNA methylation.
abstract: BACKGROUND
  To study the expression of the RIZ1 (Retinoblastoma protein-interacting zinc-finger gene 1) gene and investigate the promoter region methylation status of RIZ1 gene in the human esophageal squamous cell carcinoma (ESCC) cell lines of KYSE150, KYSE510, TE13, EC9706, CaEsl7, and EC109. To investigate the influence of DNMT (DNA methyltransferase) 5-aza-CdR(5-aza-2'-deoxycytidine) on the transcription of the RIZ1 gene in one cell line whose RIZ1 gene promoter region methylation was detected, and to investigate its influence on the cell proliferation.
  
  
  METHODS
  Real-time PCR (Real-time quantitative PCR) and an immunohistochemistry technique was used to get the expression of RIZ1 in specimens from 6 human ESCC cell lines and 28 ESCC patients (tumor tissues and adjacent non-cancerous tissues). MSP (Methylation-specific PCR) was used to investigate the promoter region methylation status of the RIZ1 gene in the 6 ESCC cell lines. One cell line, whose RIZ1 gene promoter region methylation was detected, was chosen for the next studies in which it was treated it by with 5-aza-CdR. Real-time PCR was used to investigate its influence on the transcription of RIZ1 gene and MTT (methyl thiazolyl tetrazolium) was used to detect if 5-aza-CdR inhibits the proliferation of the cell line.
  
  
  RESULTS
  In the 28 ESCC patient samples, RIZ1 expression was significantly lower in the tumor tissues than that in their adjacent non-cancerous tissues (p < 0.05). Consistently, immunohistochemistry analyses of RIZ1 protein expression showed that in the ESCC tissues RIZ1 protein expression was also significantly lower than in the adjacent tissues. In the human ESCC tissues the rate of expression accounts for 0% (0/12), and in the adjacent noncancerous tissues the rate of expression was 66.7% (8/12), the correlation was highly significant (chi2 = 12.000, p < 0.05). Promoter methylation of the RIZ1 gene was detected in TE13, CaEsl7, EC109. The cell line TE13 was chosen for the next studies. The expression of RIZ1 mRNA in TE-13 was up-regulated after having been treated with 5-aza-CdR. 5-aza-CdR inhibited cell proliferation of TE-13 in a time and concentration-dependent manner.
  
  
  CONCLUSIONS
  Promoter methylation may play an important role in the epigenetic silencing of RIZ1 gene expression. Methylation of the RIZ1 promoter and loss of RIZ1 expression in human ESCC are independent biomarkers. Their determination may offer guidance for selecting appropriate diagnoses and treatments. RIZ1 may be a potential tumor suppressor in human ESCC.
authors.affiliation: Department of Cardiothoracic Surgery, Tianjin Medical University General Hospital, AnShan Road No.154, Heping District, Tianjin 300052, China.
authors.forename: Shang-Wen
authors.initials: SW
authors.lastname: Dong
authors.forename: Yuan-Tao
authors.initials: YT
authors.lastname: Cui
authors.forename: Rong-Rong
authors.initials: RR
authors.lastname: Zhong
authors.forename: Dong-Chun
authors.initials: DC
authors.lastname: Liang
authors.forename: Yi-Mei
authors.initials: YM
authors.lastname: Liu
authors.forename: Yuan-Guo
authors.initials: YG
authors.lastname: Wang
authors.forename: Zhun
authors.initials: Z
authors.lastname: He
authors.forename: Shuo
authors.initials: S
authors.lastname: Wang
authors.forename: Shao-Jie
authors.initials: SJ
authors.lastname: Liang
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D019175:DNA Methylation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D000077209:Decitabine; D004354:Drug Screening Assays, Antitumor; D004938:Esophageal Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000964:Antimetabolites, Antineoplastic; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D000077209:Decitabine; D011495:Histone-Lysine N-Methyltransferase; C093563:PRDM2 protein, human; D001374:Azacitidine