title: Increased μ-opioid receptor expression in metastatic lung cancer.
abstract: BACKGROUND
  We and others have previously demonstrated that the μ-opioid receptor (MOR) is overexpressed in several human malignancies. There is a seven-fold increase in MOR in cell lines of human lung cancer. In animal models, overexpression of MOR promotes tumour growth and metastasis. We, therefore, examined whether MOR expression is increased in metastatic lung cancer.
  
  
  METHODS
  In this study, we examined the association between MOR expression and metastasis in archived biopsy samples from patients with lung cancer. Paraffin-embedded patient material was stained using MOR antibody and scored qualitatively by two independent pathologists using a four-point scale.
  
  
  RESULTS
  In human lung cancer and normal adjacent lung samples obtained from 34 lung cancer patients, MOR expression was increased significantly in cancer samples from patients with lung cancer compared with adjacent control tissue (P=0.0242). When the samples from patients with metastatic lung cancer were separated from the cohort of the total number of patients with lung cancer, we observed an approximately two-fold increase in MOR expression (P=0.0013).
  
  
  CONCLUSIONS
  The association between the expression of MOR and the progression of the tumour is consistent with the hypothesis of a direct effect of MOR on cancer progression.
authors.affiliation: Department of Medicine, Section of Pulmonary and Critical Care, Department of Anesthesia and Critical Care and psinglet@medicine.bsd.uchicago.edu.
authors.forename: P A
authors.initials: PA
authors.lastname: Singleton
authors.affiliation: Department of Medicine, Section of Pulmonary and Critical Care.
authors.forename: T
authors.initials: T
authors.lastname: Mirzapoiazova
authors.affiliation: Section of Hematology/Oncology, Pritzker School of Medicine, The University of Chicago, Chicago, IL 60637, USA.
authors.forename: R
authors.initials: R
authors.lastname: Hasina
authors.affiliation: Section of Hematology/Oncology, Pritzker School of Medicine, The University of Chicago, Chicago, IL 60637, USA.
authors.forename: R
authors.initials: R
authors.lastname: Salgia
authors.affiliation: Department of Anesthesia and Critical Care and.
authors.forename: J
authors.initials: J
authors.lastname: Moss
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism / Q000473:pathology / Q000556:secondary*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism; D009367:Neoplasm Staging; D017450:Receptors, Opioid, mu / Q000378:metabolism*
chemical_list: D009363:Neoplasm Proteins; D017450:Receptors, Opioid, mu
keywords: MOR; lung cancer; metastasis; methylnaltrexone; μ-opioid receptor