title: Frequent downregulation of the transcription factor Foxa2 in lung cancer through epigenetic silencing.
abstract: OBJECTIVE
  We sought to determine the mechanisms of downregulation of the airway transcription factor Foxa2 in lung cancer and the expression status of Foxa2 in non-small-cell lung cancer (NSCLC).
  
  
  METHODS
  A series of 25 lung cancer cell lines were evaluated for Foxa2 protein expression, FOXA2 mRNA levels, FOXA2 mutations, FOXA2 copy number changes and for evidence of FOXA2 promoter hypermethylation. In addition, 32 NSCLCs were sequenced for FOXA2 mutations and 173 primary NSCLC tumors evaluated for Foxa2 expression using an immunohistochemical assay.
  
  
  RESULTS
  Out of the 25 cell lines, 13 (52%) had undetectable FOXA2 mRNA. The expression of FOXA2 mRNA and Foxa2 protein were congruent in 19/22 cells (p = 0.001). FOXA2 mutations were not identified in primary NSCLCs and were infrequent in cell lines. Focal or broad chromosomal deletions involving FOXA2 were not present. The promoter region of FOXA2 had evidence of hypermethylation, with an inverse correlation between FOXA2 mRNA expression and presence of CpG dinucleotide methylation (p < 0.0001). In primary NSCLC tumor specimens, there was a high frequency of either absence (42/173, 24.2%) or no/low expression (96/173, 55.4%) of Foxa2. In 130 patients with stage I NSCLC there was a trend towards decreased survival in tumors with no/low expression of Foxa2 (HR of 1.6, 95%CI 0.9-3.1; p = 0.122).
  
  
  CONCLUSIONS
  Loss of expression of Foxa2 is frequent in lung cancer cell lines and NSCLCs. The main mechanism of downregulation of Foxa2 is epigenetic silencing through promoter hypermethylation. Further elucidation of the involvement of Foxa2 and other airway transcription factors in the pathogenesis of lung cancer may identify novel therapeutic targets.
authors.affiliation: Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Daniela S
authors.initials: DS
authors.lastname: Basseres
authors.forename: Francesco
authors.initials: F
authors.lastname: D'Alò
authors.forename: Beow Y
authors.initials: BY
authors.lastname: Yeap
authors.forename: Ester C
authors.initials: EC
authors.lastname: Löwenberg
authors.forename: David A
authors.initials: DA
authors.lastname: Gonzalez
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yasuda
authors.forename: Tajhal
authors.initials: T
authors.lastname: Dayaram
authors.forename: Olivier N
authors.initials: ON
authors.lastname: Kocher
authors.forename: John J
authors.initials: JJ
authors.lastname: Godleski
authors.forename: William G
authors.initials: WG
authors.lastname: Richards
authors.forename: Matthew
authors.initials: M
authors.lastname: Meyerson
authors.forename: Susumu
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Tenen
authors.forename: Balázs
authors.initials: B
authors.lastname: Halmos
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Costa
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D045744:Cell Line, Tumor; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D015536:Down-Regulation; D044127:Epigenesis, Genetic; D005260:Female; D018628:Gene Dosage; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D051542:Hepatocyte Nuclear Factor 3-beta / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011401:Promoter Regions, Genetic
chemical_list: C496502:FOXA2 protein, human; D051542:Hepatocyte Nuclear Factor 3-beta