title: Morphine-induced epidermal growth factor pathway activation in non-small cell lung cancer.
abstract: BACKGROUND
  Epidermal growth factor receptor (EGFR) is coactivated by the μ-opioid receptor (MOR), expressed on non-small cell lung cancer (NSCLC) cells and human lung cancer. We hypothesized that clinically used opioid analgesics that are MOR agonists coactivate EGFR, resulting in growth- and survival-promoting signaling.
  
  
  METHODS
  We used H2009, a human adenocarcinoma NSCLC cell line, with constitutive EGFR phosphorylation, which showed increased expression of MOR and the δ-opioid receptor by reverse transcriptase polymerase chain reaction. We used Western immunoblotting, magnetic bead-based Bio-Plex cytokine assay, immunofluorescent staining, BrdU incorporation enzyme-linked immunosorbent assay, and BioCoat™ Matrigel™ invasion assay to examine cell signaling, cytokine expression, colocalization of MOR and EGFR in human lung cancer, and cell proliferation and invasion, respectively.
  
  
  RESULTS
  Similar to epidermal growth factor (EGF), morphine stimulated phosphorylation of EGFR, Akt/protein kinase B (Akt), and mitogen-activated protein kinase/extracellular signal regulated kinase (MAPK/ERK) signaling in H2009 cells. Opioid receptor (OR) antagonist, naloxone, EGFR tyrosine kinase inhibitor, erlotinib, and silencing of MOR and δ-opioid receptor abrogated morphine- and EGF-induced phosphorylation of signaling, suggestive of OR-mediated coactivation of EGFR. H2009 cells secreted significantly higher levels of cytokines compared with control Beas2B epithelial cells. H2009-conditioned medium stimulated MOR expression in Beas2B cells, suggesting that cytokines secreted by H2009 may be associated with increased OR expression in H2009. We observed colocalization of EGFR and MOR, in human NSCLC tissue. Functionally, morphine- and EGF-induced proliferation and invasion of H2009 cells was ameliorated by naloxone as well as erlotinib.
  
  
  CONCLUSIONS
  Morphine-induced phosphorylation of EGFR occurs via ORs, leading to downstream MAPK/ERK, Akt phosphorylation, cell proliferation, and increased invasion. Notably, ORs are also associated with EGF-induced phosphorylation of EGFR. Increased coexpression of MOR and EGFR in human lung cancer suggests that morphine may have a growth-promoting effect in lung cancer.
authors: Department of Medicine, Division of Hematology, Oncology, Transplantation, University of Minnesota, Minneapolis, MN 55455, USA.
authors: Naomi
authors: N
authors: Fujioka
authors: Julia
authors: J
authors: Nguyen
authors: Chunsheng
authors: C
authors: Chen
authors: Yunfang
authors: Y
authors: Li
authors: Teena
authors: T
authors: Pasrija
authors: Gloria
authors: G
authors: Niehans
authors: Katherine N
authors: KN
authors: Johnson
authors: Vinita
authors: V
authors: Gupta
authors: Robert A
authors: RA
authors: Kratzke
authors: Kalpna
authors: K
authors: Gupta
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000201:enzymology*; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D004815:Epidermal Growth Factor / Q000378:metabolism* / Q000502:physiology; D066246:ErbB Receptors / Q000378:metabolism* / Q000502:physiology; D000069347:Erlotinib Hydrochloride; D006801:Humans; D008175:Lung Neoplasms / Q000201:enzymology / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D009020:Morphine / Q000494:pharmacology*; D011799:Quinazolines / Q000494:pharmacology; D017450:Receptors, Opioid, mu / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology
chemical_list: D011799:Quinazolines; D017450:Receptors, Opioid, mu; D004815:Epidermal Growth Factor; D009020:Morphine; D000069347:Erlotinib Hydrochloride; D066246:ErbB Receptors