title: Effects of cancer-associated EPHA3 mutations on lung cancer.
abstract: BACKGROUND
  Cancer genome sequencing efforts recently identified EPHA3, which encodes the EPHA3 receptor tyrosine kinase, as one of the most frequently mutated genes in lung cancer. Although receptor tyrosine kinase mutations often drive oncogenic conversion and tumorigenesis, the oncogenic potential of the EPHA3 mutations in lung cancer remains unknown.
  
  
  METHODS
  We used immunoprecipitation, western blotting, and kinase assays to determine the activity and signaling of mutant EPHA3 receptors. A mutation-associated gene signature was generated from one large dataset, mapped to another training dataset with survival information, and tested in a third independent dataset. EPHA3 expression levels were determined by quantitative reverse transcription-polymerase chain reaction in paired normal-tumor clinical specimens and by immunohistochemistry in human lung cancer tissue microarrays. We assessed tumor growth in vivo using A549 and H1299 human lung carcinoma cell xenografts in mice (n = 7-8 mice per group). Tumor cell proliferation was measured by bromodeoxyuridine incorporation and apoptosis by multiple assays. All P values are from two-sided tests.
  
  
  RESULTS
  At least two cancer-associated EPHA3 somatic mutations functioned as dominant inhibitors of the normal (wild type) EPHA3 protein. An EPHA3 mutation-associated gene signature that was associated with poor patient survival was identified. Moreover, EPHA3 gene copy numbers and/or expression levels were decreased in tumors from large cohorts of patients with lung cancer (eg, the gene was deleted in 157 of 371 [42%] primary lung adenocarcinomas). Reexpression of wild-type EPHA3 in human lung cancer lines increased apoptosis by suppression of AKT activation in vitro and inhibited the growth of tumor xenografts (eg, for H1299 cells, mean tumor volume with wild-type EPHA3 = 437.4 mm(3) vs control = 774.7 mm(3), P < .001). Tumor-suppressive effects of wild-type EPHA3 could be overridden in trans by dominant negative EPHA3 somatic mutations discovered in patients with lung cancer.
  
  
  CONCLUSIONS
  Cancer-associated EPHA3 mutations attenuate the tumor-suppressive effects of normal EPHA3 in lung cancer.
authors: Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors: Guanglei
authors: G
authors: Zhuang
authors: Wenqiang
authors: W
authors: Song
authors: Katherine
authors: K
authors: Amato
authors: Yoonha
authors: Y
authors: Hwang
authors: Keunwook
authors: K
authors: Lee
authors: Mark
authors: M
authors: Boothby
authors: Fei
authors: F
authors: Ye
authors: Yan
authors: Y
authors: Guo
authors: Yu
authors: Y
authors: Shyr
authors: Luping
authors: L
authors: Lin
authors: David P
authors: DP
authors: Carbone
authors: Dana M
authors: DM
authors: Brantley-Sieders
authors: Jin
authors: J
authors: Chen
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000737:chemistry* / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004252:DNA Mutational Analysis; D018076:DNA, Complementary / Q000032:analysis; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000737:chemistry* / Q000235:genetics*; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D018579:Patient Selection; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis* / Q000235:genetics*; D036121:Receptor, EphA3; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014183:Transplantation, Heterologous; D015854:Up-Regulation
chemical_list: D000970:Antineoplastic Agents; D018076:DNA, Complementary; D004273:DNA, Neoplasm; C491718:EPHA3 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D036121:Receptor, EphA3; D051057:Proto-Oncogene Proteins c-akt