title: Identification and characterization of ALK kinase splicing isoforms in non-small-cell lung cancer.
abstract: BACKGROUND
  Anaplastic lymphoma kinase (ALK) rearrangements are present in an important subset of non-small-cell lung cancer (NSCLC) and predict for response to the tyrosine kinase inhibitor crizotinib. In this study, we evaluated the yet unknown frequency and functional role of ALK splicing isoforms in NSCLC.
  
  
  METHODS
  We analyzed 270 cases of NSCLC for ALK kinase domain splicing aberrations and in addition generated constructs with full-length echinoderm microtubule-associated protein-like 4 (EML4)-ALK (E13;A20) and a splicing isoform.
  
  
  RESULTS
  Splicing isoforms of the kinase domain of ALK-including complete skipping of exon 23 (ALKdel23, ALK p.I1171fs*42) and exon 27 (ALKdel27, ALK p.T1312fs*0)-were identified in 11.1% (30 of 270 cases) of NSCLC, and these changes coexisted with ALK rearrangements, KRAS mutations, and EGFR mutations. ALK splicing isoforms were observed with full-length EML4-ALK in crizotinib-naive and treated NSCLCs. ALK T1312fs*0 was unable to render cells solely dependent on ALK signaling. Unlike EML4-ALK and EML4-ALK p.L1196M, EML4-ALK T1312fs*0 did not autophosphorylate ALK or other phosphotyrosine sites. Coexpression of equal amounts of EML4-ALK T1312fs*0 and EML4-ALK did not result in resistance to crizotinib, whereas coexpression of EML4-ALK L1196M with EML4-ALK resulted in resistance to inhibition of ALK by crizotinib.
  
  
  CONCLUSIONS
  ALK kinase splicing isoforms were present in NSCLC and even if translated seemed to be nonfunctional variants of ALK.
authors.affiliation: *Department of Medicine, Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Boston, Massachusetts; †Department of Pathology, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China; and ‡Department of Medical Oncology, Lowe Center for Thoracic Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts.
authors.forename: Lorena Lobo
authors.initials: LL
authors.lastname: de Figueiredo-Pontes
authors.forename: Daisy Wing-Sze
authors.initials: DW
authors.lastname: Wong
authors.forename: Vicky Pui-Chi
authors.initials: VP
authors.lastname: Tin
authors.forename: Lap-Ping
authors.initials: LP
authors.lastname: Chung
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yasuda
authors.forename: Norihiro
authors.initials: N
authors.lastname: Yamaguchi
authors.forename: Sohei
authors.initials: S
authors.lastname: Nakayama
authors.forename: Pasi Antero
authors.initials: PA
authors.lastname: Jänne
authors.forename: Maria Pik
authors.initials: MP
authors.lastname: Wong
authors.forename: Susumu Soeda
authors.initials: SS
authors.lastname: Kobayashi
authors.forename: Daniel Botelho
authors.initials: DB
authors.lastname: Costa
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017398:Alternative Splicing / Q000235:genetics*; D000077548:Anaplastic Lymphoma Kinase; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D000077547:Crizotinib; D005091:Exons / Q000235:genetics; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D047468:Immunoprecipitation; D007527:Isoenzymes; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D011379:Prognosis; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use; D011720:Pyrazoles / Q000627:therapeutic use; D011725:Pyridines / Q000627:therapeutic use; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D012189:Retrospective Studies
chemical_list: C522504:EML4-ALK fusion protein, human; D007527:Isoenzymes; D015514:Oncogene Proteins, Fusion; D047428:Protein Kinase Inhibitors; D011720:Pyrazoles; D011725:Pyridines; D000077547:Crizotinib; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D020794:Receptor Protein-Tyrosine Kinases