title: Promoter hypermethylation of p16 and APC in gastrointestinal cancer patients.
abstract: OBJECTIVE
  Cancer is a consequence of the disruption of cellular regulation. Epigenetic is one of the reasons of this disruption. Epigenetic factors play a role in the carcinogenesis by affecting proto-oncogenes and tumor suppressor genes and it is one of the most popular research areas in recent years. DNA methylation, which is an epigenetic mechanism, occurs in the early stages of tumorigenesis. Promoter methylation which causes the silence of tumor suppressor genes have been studied extensively in various tumor types. The aim of this study was to investigate promoter methylation of certain tumor suppressor genes, Cyclin-dependent kinase inhibitor 2A (p16) and Adenomatous polyposis coli (APC), which take part in gastrointestinal tumorigenesis.
  
  
  METHODS
  To detect the promoter methylation of p16 and APC genes, tissue samples from 20 gastrointestinal cancer patients and peripheral blood samples from 15 healthy individuals were collected for Methylation-Specific Polymerase Chain Reaction (MSP) analysis.
  
  
  RESULTS
  According to the statistical analysis, in tumor tissue, positive methylation ratio of p16 and APC genes was found respectively 30% (6/20) and 50% (10/20). The difference of promoter methylation of these genes between tumor tissues and control group was significantly observed (p=0.02 and 0.001, respectively). An alteration of promoter methylation of APC gene according to tumor localization was found (p=0.007), but there was no significant difference observed in p16.
  
  
  CONCLUSIONS
  In our study, promoter methylation which was considered to be occurred as an early event in gastrointestinal carcinogenesis was observed in p16 and APC genes.
authors.affiliation: Department of Biology, Hacettepe University Faculty of Science, Ankara, Turkey. mergen@hacettepe.edu.tr.
authors.forename: Beril
authors.initials: B
authors.lastname: Erdem
authors.forename: Sibel
authors.initials: S
authors.lastname: Küçükyıldırım
authors.forename: Emel
authors.initials: E
authors.lastname: Sağlar
authors.forename: Zülfikar
authors.initials: Z
authors.lastname: Polat
authors.forename: Hatice
authors.initials: H
authors.lastname: Mergen
mesh_terms: D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics*; D000367:Age Factors; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics*; D004247:DNA / Q000032:analysis* / Q000097:blood; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005770:Gastrointestinal Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology*; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D011401:Promoter Regions, Genetic
chemical_list: C555337:APC protein, human; D025601:Adenomatous Polyposis Coli Protein; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004247:DNA