MAP2K1 (MEK1) Mutations Define a Distinct Subset of Lung Adenocarcinoma Associated with Smoking

Clin Cancer Res. 2015 Apr 15;21(8):1935-43. doi: 10.1158/1078-0432.CCR-14-2124. Epub 2014 Oct 28.

Abstract

Purpose: Genetic alterations affecting the MAPK/ERK pathway are common in lung adenocarcinoma (LAD). Early steps of the signaling pathway are most often affected with EGFR, KRAS, and BRAF mutations encompassing more than 70% of all alterations. Somatic mutations in MEK1, located downstream of BRAF, are rare and remain poorly defined as a distinct molecular subset.

Experimental design: Tumors harboring MEK1 mutations were identified through targeted screening of a large LAD cohort concurrently interrogated for recurrent mutations in MEK1, EGFR, KRAS, BRAF, ERBB2/HER2, NRAS, PIK3CA, and AKT. Additional cases were identified through a search of publically available cancer genomic datasets. Mutations were correlated with patient characteristics and treatment outcomes. Overall survival was compared with stage-matched patients with KRAS- and EGFR-mutant LADs.

Results: We identified 36 MEK1-mutated cases among 6,024 LAD (0.6%; 95% confidence interval, 0.42-0.85). The majority of patients were smokers (97%, n = 35/36). There was no association with age, sex, race, or stage. The most common mutations were K57N (64%, 23/36) followed by Q56P (19%, 7/36), all mutually exclusive with other driver mutations in the targeted panel. Transversions G:C>T:A were predominant (89%, 31/35), in keeping with smoking-associated DNA damage. Additional less common somatic mutations were identified in the kinase domain, all of which are predicted to converge into a single interaction area based on in silico 3D modeling.

Conclusions: MEK1 mutations define a distinct subset of lung cancers (∼1%) with potential sensitivity to MEK inhibitors. Mutations are predominantly transversions, in keeping with a strong association with smoking.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenocarcinoma / etiology*
  • Adenocarcinoma / mortality
  • Adenocarcinoma / pathology*
  • Adenocarcinoma of Lung
  • Aged
  • Aged, 80 and over
  • Alleles
  • Cell Line
  • DNA Mutational Analysis
  • Exons
  • Female
  • Gene Frequency
  • Genotype
  • Humans
  • Lung Neoplasms / etiology*
  • Lung Neoplasms / mortality
  • Lung Neoplasms / pathology*
  • MAP Kinase Kinase 1 / chemistry
  • MAP Kinase Kinase 1 / genetics*
  • MAP Kinase Kinase 1 / metabolism
  • Male
  • Middle Aged
  • Models, Molecular
  • Mutation*
  • Neoplasm Metastasis
  • Neoplasm Staging
  • Prognosis
  • Protein Conformation
  • Smoking / adverse effects*

Substances

  • MAP Kinase Kinase 1