title: Downregulation of metallothionein 1F, a putative oncosuppressor, by loss of heterozygosity in colon cancer tissue.
abstract: OBJECTIVE
  Downregulation of metallothionein (MT) genes has been reported in several tumors with discrepant results. This study is to investigate molecular mechanism of MT gene regulation in colon cancer which is characterized by tumor suppressor gene alterations.
  
  
  METHODS
  Integral analysis of microarray data with loss of heterozygosity (LOH) information was employed. Quantitative real-time PCR and immunohistochemistry were used to validate MT isoform expression in colon cancer tissues and cell lines. The effects of MT1F expression on RKO cell survival and tumorigenesis was analyzed. Bisulphite sequencing PCR (BSP) and methylation-specific PCR were employed to detect the methylation status of the MT1F gene in colon cancer tissues and cell lines. DNA sequencing was used to examine the LOH at the MT1F locus.
  
  
  RESULTS
  MT1F, MT1G, MT1X, and MT2A gene expression was significantly downregulated in colon cancer tissue (p<0.05). Exogenous MT1F expression increased RKO cell apoptosis and inhibited RKO cell migration, invasion and adhesion as well as in vivo tumorigenicity. Downregulation of MT1F gene in majority of human colon tumor tissues is mainly through mechanism by loss of heterozygosity (p=0.001) while CpG island methylation of MT1F gene promoter region was only observed in poorly differentiated, MSI-positive RKO and LoVo colon cancer cell lines.
  
  
  CONCLUSIONS
  MT1F is a putative tumor suppressor gene in colon carcinogenesis that is downregulated mainly by LOH in colon cancer tissue. Further studies are required to elucidate a possible role for MT1F downregulation in colon cancer initiation and/or progression.
authors.affiliation: Department of General Surgery, Shanghai Jiaotong University Affiliated First People's Hospital, 85 Wujin Road, People's Republic of China.
authors.forename: Dong-Wang
authors.initials: DW
authors.lastname: Yan
authors.forename: Jun-Wei
authors.initials: JW
authors.lastname: Fan
authors.forename: Zhen-Hai
authors.initials: ZH
authors.lastname: Yu
authors.forename: Ming-Xue
authors.initials: MX
authors.lastname: Li
authors.forename: Yu-Gang
authors.initials: YG
authors.lastname: Wen
authors.forename: Da-Wei
authors.initials: DW
authors.lastname: Li
authors.forename: Chong-Zhi
authors.initials: CZ
authors.lastname: Zhou
authors.forename: Xiao-Liang
authors.initials: XL
authors.lastname: Wang
authors.forename: Quan
authors.initials: Q
authors.lastname: Wang
authors.forename: Hua-Mei
authors.initials: HM
authors.lastname: Tang
authors.forename: Zhi-Hai
authors.initials: ZH
authors.lastname: Peng
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D017209:Apoptosis; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002465:Cell Movement; D003110:Colonic Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D018899:CpG Islands; D019175:DNA Methylation; D015536:Down-Regulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D016147:Genes, Tumor Suppressor; D006801:Humans; D019656:Loss of Heterozygosity; D008297:Male; D008668:Metallothionein / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA; D014183:Transplantation, Heterologous
chemical_list: C501902:MT1F protein, human; C499629:MT1G protein, human; C491053:MT2A protein, human; D008668:Metallothionein