title: Promoter methylation of CDKN2A and lack of p16 expression characterize patients with hepatocellular carcinoma.
abstract: BACKGROUND
  The product of CDKN2A, p16 is an essential regulator of the cell cycle controlling the entry into the S-phase. Herein, we evaluated CDKN2A promoter methylation and p16 protein expression for the differentiation of hepatocellular carcinoma (HCC) from other liver tumors.
  
  
  METHODS
  Tumor and corresponding non-tumor liver tissue samples were obtained from 85 patients with liver tumors. CDKN2A promoter methylation was studied using MethyLight technique and methylation-specific PCR (MSP). In the MethyLight analysis, samples with > or = 4% of PMR (percentage of methylated reference) were regarded as hypermethylated. p16 expression was evaluated by immunohistochemistry in tissue sections (n = 148) obtained from 81 patients using an immunoreactivity score (IRS) ranging from 0 (no expression) to 6 (strong expression).
  
  
  RESULTS
  Hypermethylation of the CDKN2A promoter was found in 23 HCCs (69.7%; mean PMR = 42.34 +/- 27.8%), six (20.7%; mean PMR = 31.85 +/- 18%) liver metastases and in the extralesional tissue of only one patient. Using MSP, 32% of the non-tumor (n = 85), 70% of the HCCs, 40% of the CCCs and 24% of the liver metastases were hypermethylated. Correspondingly, nuclear p16 expression was found immunohistochemically in five (10.9%, mean IRS = 0.5) HCCs, 23 (92%; mean IRS = 4.9) metastases and only occasionally in hepatocytes of non-lesional liver tissues (mean IRS = 1.2). The difference of CDKN2A-methylation and p16 protein expression between HCCs and liver metastases was statistically significant (p < 0.01, respectively).
  
  
  CONCLUSIONS
  Promoter methylation of CDKN2A gene and lack of p16 expression characterize patients with HCC.
authors.affiliation: Department of Gastroenterology, Hepatology, and Infectious Diseases, Otto-von-Guericke University, 39120 Magdeburg, Germany. csepregia@yahoo.de
authors.forename: Antal
authors.initials: A
authors.lastname: Csepregi
authors.forename: Matthias Pa
authors.initials: MP
authors.lastname: Ebert
authors.forename: Christoph
authors.initials: C
authors.lastname: Röcken
authors.forename: Regine
authors.initials: R
authors.lastname: Schneider-Stock
authors.forename: Juliane
authors.initials: J
authors.lastname: Hoffmann
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Schulz
authors.forename: Albert
authors.initials: A
authors.lastname: Roessner
authors.forename: Peter
authors.initials: P
authors.lastname: Malfertheiner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000737:chemistry* / Q000235:genetics* / Q000473:pathology; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000032:analysis / Q000235:genetics; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000737:chemistry* / Q000235:genetics* / Q000473:pathology / Q000556:secondary; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic
chemical_list: D014408:Biomarkers, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16