title: Epigenetic abnormalities in cutaneous squamous cell carcinomas: frequent inactivation of the RB1/p16 and p53 pathways.
abstract: BACKGROUND
  Aberrant methylation of CpG islands in the promoter regions of cancer-related genes has been demonstrated in many human tumours. However, the methylation profile of these regions in cutaneous squamous cell carcinomas (SCCs) has not been well studied.
  
  
  OBJECTIVE
  To examine epigenetic abnormalities of a wide range of cancer-related genes in SCCs.
  
  
  METHODS
  We investigated the methylation status of 11 candidate cancer-related genes (CDH1, p16(INK4a), p14(ARF), DAPK1, MGMT, RB1, RASSF1, p15(INK4b), PTEN, PRDM2 and p53) in 20 cases of SCC by methylation-specific polymerase chain reaction, and comparatively examined the protein production of E-cadherin (CDH1), p16, RB1, p14, BMI1 and cyclin A by immunohistochemical analysis.
  
  
  RESULTS
  The frequency of cancer-related gene methylation in SCCs was: CDH1 (95%), p16 (20%), p14 (15%), DAPK1 (15%), MGMT (15%), RB1 (5%), RASSF1 (5%), p15 (0%), PTEN (0%), PRDM2 (0%) and p53 (0%). Almost all cases with hypermethylation of CDH1, p16, RB1 and p14 showed no obvious production of each protein, suggesting that promoter hypermethylation of these genes contributes to the loss of protein production. The results of methylation analysis, in combination with the results of our previous mutation analysis of CDKN2A locus and p53, revealed that 70% of SCCs have alterations in the RB1/p16 or p53 pathway.
  
  
  CONCLUSIONS
  Our findings indicate that the promoter hypermethylation of cancer-related genes, especially CDH1, is frequently shown in SCCs, and dysregulation of the RB1/p16 and/or p53 pathway through either genetic or epigenetic mechanisms, except for epigenetic abnormalities of p53 itself, should contribute to the carcinogenesis of SCCs.
authors.affiliation: Department of Dermatology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Murao
authors.forename: Y
authors.initials: Y
authors.lastname: Kubo
authors.forename: N
authors.initials: N
authors.lastname: Ohtani
authors.forename: E
authors.initials: E
authors.lastname: Hara
authors.forename: S
authors.initials: S
authors.lastname: Arase
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000235:genetics; D044127:Epigenesis, Genetic; D020868:Gene Silencing; D019942:Genes, p16; D016158:Genes, p53 / Q000235:genetics*; D006801:Humans; D007124:Immunoenzyme Techniques; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D012878:Skin Neoplasms / Q000235:genetics*
chemical_list: D004273:DNA, Neoplasm