title: DNA methylation status of REIC/Dkk-3 gene in human malignancies.
abstract: OBJECTIVE
  The REIC (reduced expression in immortalized cells)/Dkk-3 is down-regulated in various cancers and considered to be a tumor suppressor gene. REIC/Dkk-3 mRNA has two isoforms (type-a,b). REIC type-a mRNA has shown to be a major transcript in various cancer cells, and its promoter activity was much stronger than that of type-b. In this study, we examined the methylation status of REIC/Dkk-3 type-a in a broad range of human malignancies.
  
  
  METHODS
  We examined REIC/Dkk-3 type-a methylation in breast cancers, non-small-cell lung cancers, gastric cancers, colorectal cancers, and malignant pleural mesotheliomas using a quantitative combined bisulfite restriction analysis assay and bisulfate sequencing. REIC/Dkk-3 type-a and type-b expression was examined using reverse transcriptional PCR. The relationships between the methylation and clinicopathological factors were analyzed.
  
  
  RESULTS
  The rate of REIC/Dkk-3 type-a methylation ranged from 26.2 to 50.0% in the various primary tumors that were examined. REIC/Dkk-3 type-a methylation in breast cancer cells was significantly heavier than that in the other cell lines that we tested. REIC/Dkk-3 type-a methylation was inversely correlated with REIC/Dkk-3 type-a expression. There was a correlation between REIC/Dkk-3 type-a and type-b mRNA expression. REIC/Dkk-3 type-a expression was restored in MDA-MB-231 cells using 5-aza-2'-deoxycytidine treatment. We found that estrogen receptor-positive breast cancers were significantly more common among the methylated group than among the non-methylated group.
  
  
  CONCLUSIONS
  REIC/Dkk-3 type-a methylation was frequently detected in a broad range of cancers and appeared to play a key role in silencing REIC/Dkk-3 type-a expression in these malignancies.
authors.affiliation: Department of Cancer and Thoracic Surgery, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Shikata-cho, Okayama, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Hayashi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Asano
authors.forename: Shinichi
authors.initials: S
authors.lastname: Toyooka
authors.forename: Kazunori
authors.initials: K
authors.lastname: Tsukuda
authors.forename: Junichi
authors.initials: J
authors.lastname: Soh
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Shien
authors.forename: Naruto
authors.initials: N
authors.lastname: Taira
authors.forename: Yuho
authors.initials: Y
authors.lastname: Maki
authors.forename: Norimitsu
authors.initials: N
authors.lastname: Tanaka
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Doihara
authors.forename: Yasutomo
authors.initials: Y
authors.lastname: Nasu
authors.forename: Nam-Ho
authors.initials: NH
authors.lastname: Huh
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Miyoshi
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D018925:Chemokines; D019175:DNA Methylation / Q000502:physiology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing / Q000502:physiology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D008297:Male; D009369:Neoplasms / Q000235:genetics* / Q000473:pathology; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018925:Chemokines; C498624:DKK3 protein, human; D036341:Intercellular Signaling Peptides and Proteins