title: Quantitative analysis of promoter hypermethylation in multiple genes in osteosarcoma.
abstract: BACKGROUND
  Osteosarcoma is the most common solid malignant diseases of childhood, occurring in approximately 6 children per million annually; however, to the authors' knowledge to date, the cause of osteosarcoma has remained mostly unknown. Genetic alterations of genes that are specific for osteosarcoma have not been identified. Genetic alternations in the status of DNA methylation, known as epigenetic alterations, are the most common molecular alterations in human neoplasia. Aberrant methylation in the promoter region of tumor-related genes is associated closely with epigenetically mediated gene silencing, which is a common feature in human tumors.
  
  
  METHODS
  The authors analyzed CpG islands of 5 different gene loci for aberrant methylation profiles in 30 pairs of osteosarcoma and corresponding normal tissues by using the quantitative methylation-specific polymerase chain reaction method. The objectives of this study were to characterize the methylation changes in osteosarcoma more extensively and to identify epigenetic biomarkers that may be useful in the diagnosis and prevention of osteosarcoma.
  
  
  RESULTS
  For the Ras effector homologue (RASSF1A), tissue inhibitor of metalloproteinase 3 (TIMP3), O-6-methylguanine DNA methyltransferase (MGMT), and death-associated protein kinase 1 (DAPK1) genes, significant differences were observed in the degree of hypermethylation between tumors and normal tissues (P < 0.01 and P < 0.001, respectively). Measurement of the cumulative multiple promoter hypermethylation revealed striking differences between tumor specimens and normal tissues (t = 7.31; P < .001). There also was a significant difference in the levels of DNA methylation between the metastatic and nonmetastatic high-grade osteosarcomas (t = 4.57; P < .01). In addition, the methylation levels were associated closely with gender (t = 6.44; P < .001).
  
  
  CONCLUSIONS
  The results indicated that tumor tissues from patients with osteosarcoma had a significantly higher incidence of hypermethylation for several genes compared with corresponding normal tissues. The epigenetic changes observed in this study may have prognostic importance for patients with osteosarcoma.
authors.affiliation: Chien-Shiung Wu Laboratory, Department of Biological Science and Medical Engineering, Southeast University, Nanjing, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Hou
authors.forename: Meiju
authors.initials: M
authors.lastname: Ji
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.forename: Zaozao
authors.initials: Z
authors.lastname: Chen
authors.forename: Junjun
authors.initials: J
authors.lastname: Qiu
authors.forename: Xin
authors.initials: X
authors.lastname: Shi
authors.forename: Zuhong
authors.initials: Z
authors.lastname: Lu
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000235:genetics* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D018899:CpG Islands; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005260:Female; D052138:Genes, Neoplasm; D005819:Genetic Markers; D006801:Humans; D008297:Male; D008875:Middle Aged; D012516:Osteosarcoma / Q000235:genetics* / Q000473:pathology; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic
chemical_list: D005819:Genetic Markers