title: Activation of HER family signaling as a mechanism of acquired resistance to ALK inhibitors in EML4-ALK-positive non-small cell lung cancer.
abstract: OBJECTIVE
  Anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKI) such as crizotinib show marked efficacy in patients with non-small cell lung cancer positive for the echinoderm microtubule-associated protein-like 4 (EML4)-ALK fusion protein. However, acquired resistance to these agents has already been described in treated patients, and the mechanisms of such resistance remain largely unknown.
  
  
  METHODS
  We established lines of EML4-ALK-positive H3122 lung cancer cells that are resistant to the ALK inhibitor TAE684 (H3122/TR cells) and investigated their resistance mechanism with the use of immunoblot analysis, ELISA, reverse transcription and real-time PCR analysis, and an annexin V binding assay. We isolated EML4-ALK-positive lung cancer cells (K-3) from a patient who developed resistance to crizotinib and investigated their characteristics.
  
  
  RESULTS
  The expression of EML4-ALK was reduced at the transcriptional level, whereas phosphorylation of epidermal growth factor receptor (EGFR), HER2, and HER3 was upregulated, in H3122/TR cells compared with those in H3122 cells. This activation of HER family proteins was accompanied by increased secretion of EGF. Treatment with an EGFR-TKI induced apoptosis in H3122/TR cells, but not in H3122 cells. The TAE684-induced inhibition of extracellular signal-regulated kinase (ERK) and STAT3 phosphorylation observed in parental cells was prevented by exposure of these cells to exogenous EGF, resulting in a reduced sensitivity of cell growth to TAE684. K-3 cells also manifested HER family activation accompanied by increased EGF secretion.
  
  
  CONCLUSIONS
  EGF-mediated activation of HER family signaling is associated with ALK-TKI resistance in lung cancer positive for EML4-ALK.
authors: Department of Medical Oncology and Genome Biology, Kinki University Faculty of Medicine, Osaka-Sayama, Osaka, Japan.
authors: Junko
authors: J
authors: Tanizaki
authors: Isamu
authors: I
authors: Okamoto
authors: Takafumi
authors: T
authors: Okabe
authors: Kazuko
authors: K
authors: Sakai
authors: Kaoru
authors: K
authors: Tanaka
authors: Hidetoshi
authors: H
authors: Hayashi
authors: Hiroyasu
authors: H
authors: Kaneda
authors: Ken
authors: K
authors: Takezawa
authors: Kiyoko
authors: K
authors: Kuwata
authors: Haruka
authors: H
authors: Yamaguchi
authors: Erina
authors: E
authors: Hatashita
authors: Kazuto
authors: K
authors: Nishio
authors: Kazuhiko
authors: K
authors: Nakagawa
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy*; D049109:Cell Proliferation / Q000187:drug effects; D000077547:Crizotinib; D019008:Drug Resistance, Neoplasm; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D020128:Inhibitory Concentration 50; D008175:Lung Neoplasms / Q000188:drug therapy*; D015514:Oncogene Proteins, Fusion / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D015398:Signal Transduction; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; C522504:EML4-ALK fusion protein, human; C516714:NVP-TAE684; D015514:Oncogene Proteins, Fusion; D047428:Protein Kinase Inhibitors; D011720:Pyrazoles; D011725:Pyridines; D011743:Pyrimidines; D000077547:Crizotinib; D066246:ErbB Receptors