title: Higher expression of receptor tyrosine kinase Axl, and differential expression of its ligand, Gas6, predict poor survival in lung adenocarcinoma patients.
abstract: BACKGROUND
  Downstream activation through receptor tyrosine kinases (RTKs) plays important roles in carcinogenesis. In this study, we assessed the clinical involvement of Axl, an RTK, and its ligand, Gas6, in surgically treated lung adenocarcinoma.
  
  
  METHODS
  Axl and Gas6 mRNA and protein expression levels were quantified using quantitative real-time polymerase chain reaction and immunohistochemistry, respectively, in completely resected lung adenocarcinoma tissues (n = 88) and were evaluated for correlation with clinicopathologic features and patient survival.
  
  
  RESULTS
  Higher expressions of Axl mRNA/protein and Gas6 protein were significantly related to worse clinicopathological features and prognosis (5-year overall survival rates: Axl mRNA low: 72.3 %, high: 49.7 %, P = 0.047; Axl protein low: 77.5 %, high: 38.6 %, P < 0.001; and Gas6 protein low: 70.5 %, high: 48 %, P = 0.042). On the contrary, higher Gas6 mRNA expression was related to better clinicopathological features and prognosis (5-year overall survival rates: Gas6 mRNA low: 59.2 %, high: 81.8 %, P = 0.054). Multivariate analysis suggests that high Axl mRNA expression may be an independent factor for poor patient prognosis (P = 0.04).
  
  
  CONCLUSIONS
  In lung adenocarcinoma, Axl and Gas6 expression levels were associated with tumor advancement and patient survival, thus rendering them as reliable biomarkers and potential targets for treatment of lung adenocarcinoma.
authors.affiliation: Department of Thoracic Surgery, Faculty of Medicine, Kyoto University, Kyoto, Japan, mishi@kuhp.kyoto-u.ac.jp.
authors.forename: Masashi
authors.initials: M
authors.lastname: Ishikawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Sonobe
authors.forename: Ei
authors.initials: E
authors.lastname: Nakayama
authors.forename: Masashi
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Kikuchi
authors.forename: Jiro
authors.initials: J
authors.lastname: Kitamura
authors.forename: Naoto
authors.initials: N
authors.lastname: Imamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Date
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000401:mortality* / Q000556:secondary; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007124:Immunoenzyme Techniques; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D008175:Lung Neoplasms / Q000235:genetics / Q000401:mortality* / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015996:Survival Rate; D000094963:Axl Receptor Tyrosine Kinase; D000099255:Growth Arrest-Specific Protein 6
chemical_list: D014408:Biomarkers, Tumor; D036341:Intercellular Signaling Peptides and Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D020794:Receptor Protein-Tyrosine Kinases; D000094963:Axl Receptor Tyrosine Kinase; D000099255:Growth Arrest-Specific Protein 6; C000722289:AXL protein, human