title: Loss of heterozygosity and methylation of multiple tumor suppressor genes on chromosome 3 in hepatocellular carcinoma.
abstract: BACKGROUND
  Genetic and epigenetic alterations are the two key mechanisms in the development of hepatocellular carcinoma (HCC). However, how they contribute to hepatocarcinogenesis and the correlation between them has not been fully elucidated.
  
  
  METHODS
  A total of 48 paired HCCs and noncancerous tissues were used to detect loss of heterozygosity (LOH) and the methylation profiles of five tumor suppressor genes (RASSF1A, BLU, FHIT, CRBP1, and HLTF) on chromosome 3 by using polymerase chain reaction (PCR) and methylation-specific PCR. Gene expression was analyzed by immunohistochemistry and reverse transcription (RT)-PCR.
  
  
  RESULTS
  Sixteen of 48 (33.3 %) HCCs had LOH on at least one locus on chromosome 3, and two smallest common deleted regions (3p22.3-24.3 and 3p12.3-14.2) were identified. RASSF1A, BLU, and FHIT showed very high frequencies of methylation in HCCs (100, 81.3, and 64.6 %, respectively) and noncancerous tissues, but not in liver tissues from control patients. Well-differentiated HCCs showed high methylation frequencies of these genes but very low frequencies of LOH. Furthermore, BLU methylation was associated with an increased level of alpha-fetoprotein, and FHIT methylation was inversely correlated with HCC recurrence. In comparison, CRBP1 showed moderate frequencies of methylation, while HLTF showed low frequencies of methylation, and CRBP1 methylation occurred mainly in elderly patients. Treatment with 5-aza-2'-deoxycytidine demethylated at least one of these genes and restored their expression in a DNA methylation-dependent or -independent manner.
  
  
  CONCLUSIONS
  Hypermethylation of RASSF1A, BLU, and FHIT is a common and very early event in hepatocarcinogenesis; CRBP1 methylation may also be involved in the later stage. Although LOH was not too frequent on chromosome 3, it may play a role as another mechanism in hepatocarcinogenesis.
authors: Institute of Pathology and Pathophysiology, Shandong University School of Medicine, Jinan, 250012, China.
authors: Xiaoying
authors: X
authors: Zhang
authors: Hiu Ming
authors: HM
authors: Li
authors: Zhiyan
authors: Z
authors: Liu
authors: Gengyin
authors: G
authors: Zhou
authors: Qinghui
authors: Q
authors: Zhang
authors: Tingguo
authors: T
authors: Zhang
authors: Jianping
authors: J
authors: Zhang
authors: Cuijuan
authors: C
authors: Zhang
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000235:genetics / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002893:Chromosomes, Human, Pair 3 / Q000235:genetics*; D003598:Cytoskeletal Proteins; D019175:DNA Methylation / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D056945:Hep G2 Cells; D006801:Humans; D053208:Kaplan-Meier Estimate; D008099:Liver / Q000378:metabolism; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism; D019656:Loss of Heterozygosity / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D054840:Retinol-Binding Proteins, Cellular / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D055815:Young Adult; D000099170:Bis(5'-adenosyl)triphosphatase
chemical_list: D017766:Acid Anhydride Hydrolases; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D054840:Retinol-Binding Proteins, Cellular; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D000099170:Bis(5'-adenosyl)triphosphatase; C100023:HLTF protein, human; C411762:RASSF1 protein, human; C518456:RBP1 protein, human; C472720:ZMYND10 protein, human