title: A comprehensive analysis of p16 expression, gene status, and promoter hypermethylation in surgically resected non-small cell lung carcinomas.
abstract: BACKGROUND
  The role of p16 is gaining importance in non-small cell lung cancer (NSCLC) because of epigenetic therapy options. Further insight into the significance of protein expression, gene status and promoter methylation is needed and has the potential to optimize existing treatment strategies.
  
  
  METHODS
  This population-based study analyzes p16 in 383 surgically resected non-small cell lung carcinomas brought into a standardized tissue microarray platform. Immunohistochemistry and fluorescence in situ hybridization were performed. For selected cases, p16 promoter hypermethylation was assessed by a pyrosequencing assay. Extensive clinical data and a postoperative follow-up period of 15 years enabled detailed correlations.
  
  
  RESULTS
  Loss of p16 expression is a common event in NSCLC (232/365, 64%), especially in squamous cell carcinomas (97/115, 84%) in contrast to adenocarcinomas (93/186, 50%). Loss of p16 expression was associated with poorer survival time for the entire cohort and for certain subgroups including men, age younger than 65 years, smokers, early tumor stage, adenocarcinoma, and large-cell carcinoma. Promoter hypermethylation was absent for cases expressing p16 but was commonly observed when (heterozygous) p16 gene deletions were present and in cases negative for p16.
  
  
  CONCLUSIONS
  Our comprehensive data would be compatible with a two-step process leading to loss of p16 expression in NSCLC. Hypermethylation of the promoter region may represent an early event, followed by heterozygous deletion of the p16 locus. Because of the possibility of detection of hypermethylated gene regions, these data may lead to the identification of specific patient subgroups more likely to benefit from upcoming demethylating treatment strategies.
authors.affiliation: Institute for Pathology, Academic Teaching Hospital Feldkirch, Affiliation of the Medical University Innsbruck, Carinagasse, Feldkirch, Austria. william.sterlacci@lkhf.at
authors.forename: William
authors.initials: W
authors.lastname: Sterlacci
authors.forename: Alexandar
authors.initials: A
authors.lastname: Tzankov
authors.forename: Lothar
authors.initials: L
authors.lastname: Veits
authors.forename: Bettina
authors.initials: B
authors.lastname: Zelger
authors.forename: Michel P
authors.initials: MP
authors.lastname: Bihl
authors.forename: Anja
authors.initials: A
authors.lastname: Foerster
authors.forename: Florian
authors.initials: F
authors.lastname: Augustin
authors.forename: Michael
authors.initials: M
authors.lastname: Fiegl
authors.forename: Spasenija
authors.initials: S
authors.lastname: Savic
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018287:Carcinoma, Large Cell / Q000235:genetics / Q000378:metabolism / Q000601:surgery; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics* / Q000378:metabolism* / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism / Q000601:surgery; D015331:Cohort Studies; D019941:Cyclin-Dependent Kinase Inhibitor p16; D019175:DNA Methylation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007124:Immunoenzyme Techniques; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism*; D009367:Neoplasm Staging; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D015996:Survival Rate; D046888:Tissue Array Analysis; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D009363:Neoplasm Proteins