title: Aberrant methylation of tumour-related genes in thymic epithelial tumours.
abstract: BACKGROUND
  Thymoma is an uncommon neoplasm derived from epithelial cells of the thymus. Few studies have addressed the genetic alterations that occur in the tumourigenesis of thymoma.
  
  
  METHODS
  We examined aberrant DNA methylation of DAP-K, p-16, MGMT and HPP1 genes in 26 thymomas and 6 thymic carcinoma to clarify the association between aberrant DNA methylation and clinicopathological features.
  
  
  RESULTS
  Fifteen (47%) of 32 thymic epithelial tumours showed aberrant methylation. Aberrant methylation was more frequent in thymic carcinoma (86%) than in thymoma (29%). Moreover, the frequency of tumours with methylation of multiple genes in thymic carcinoma was higher than in thymoma (60% vs 20%). In thymoma, the frequency of tumour methylation, including the type A tumour component (28%), was lower than that of tumours with type B tumour component (42%). MGMT methylation was detected in 23% of thymoma and in 83% of thymic carcinoma. The frequency of methylation of the MGMT gene in both tumours was high compared with the other 3 genes.
  
  
  CONCLUSIONS
  Aberrant DNA methylation was more frequent in thymic carcinoma than in thymoma, and the frequency of DNA methylation in thymic epithelial tumours is roughly parallel to their malignant behaviour.
authors.affiliation: Department of Oncological and Regenerative Surgery, Institute of Health Biosciences, The University of Tokushima Graduate School, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Hirose
authors.forename: Kazuya
authors.initials: K
authors.lastname: Kondo
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Takizawa
authors.forename: Taeko
authors.initials: T
authors.lastname: Nagao
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Fujino
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Toba
authors.forename: Koichiro
authors.initials: K
authors.lastname: Kenzaki
authors.forename: Shoji
authors.initials: S
authors.lastname: Sakiyama
authors.forename: Akira
authors.initials: A
authors.lastname: Tangoku
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D051017:Apoptosis Regulatory Proteins / Q000235:genetics; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics; D002277:Carcinoma / Q000235:genetics* / Q000473:pathology*; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics; D045643:DNA Repair Enzymes / Q000235:genetics; D064550:Death-Associated Protein Kinases; D005260:Female; D019942:Genes, p16; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D013945:Thymoma / Q000235:genetics* / Q000473:pathology*; D013953:Thymus Neoplasms / Q000235:genetics* / Q000473:pathology*; D025521:Tumor Suppressor Proteins / Q000235:genetics
chemical_list: D051017:Apoptosis Regulatory Proteins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; C423567:TMEFF2 protein, human; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D045643:DNA Repair Enzymes