title: Multi-level targeting of the phosphatidylinositol-3-kinase pathway in non-small cell lung cancer cells.
abstract: BACKGROUND
  We assessed expression of p85 and p110α PI3K subunits in non-small cell lung cancer (NSCLC) specimens and the association with mTOR expression, and studied effects of targeting the PI3K/AKT/mTOR pathway in NSCLC cell lines.
  
  
  METHODS
  Using Automated Quantitative Analysis we quantified expression of PI3K subunits in two cohorts of 190 and 168 NSCLC specimens and correlated it with mTOR expression. We studied effects of two PI3K inhibitors, LY294002 and NVP-BKM120, alone and in combination with rapamycin in 6 NSCLC cell lines. We assessed activity of a dual PI3K/mTOR inhibitor, NVP-BEZ235 alone and with an EGFR inhibitor.
  
  
  RESULTS
  p85 and p110α tend to be co-expressed (p<0.001); p85 expression was higher in adenocarcinomas than squamous cell carcinomas. High p85 expression was associated with advanced stage and poor survival. p110α expression correlated with mTOR (ρ = 0.276). In six NSCLC cell lines, addition of rapamycin to LY294002 or NVP-BKM120 was synergistic. Even very low rapamycin concentrations (1 nM) resulted in sensitization to PI3K inhibitors. NVP-BEZ235 was highly active in NSCLC cell lines with IC(50)s in the nanomolar range and resultant down-regulation of pAKT and pP70S6K. Adding Erlotinib to NVP-BEZ235 resulted in synergistic growth inhibition.
  
  
  CONCLUSIONS
  The association between PI3K expression, advanced stage and survival in NSCLC suggests that it might be a valuable drug target. Concurrent inhibition of PI3K and mTOR is synergistic in vitro, and a dual PI3K/mTOR inhibitor was highly active. Adding EGFR inhibition resulted in further growth inhibition. Targeting the PI3K/AKT/mTOR pathway at multiple levels should be tested in clinical trials for NSCLC.
authors.affiliation: Yale University School of Medicine & Yale Comprehensive Cancer, New Haven, Connecticut, United States of America.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Zito
authors.forename: Lucia B
authors.initials: LB
authors.lastname: Jilaveanu
authors.forename: Valsamo
authors.initials: V
authors.lastname: Anagnostou
authors.forename: David
authors.initials: D
authors.lastname: Rimm
authors.forename: Gerold
authors.initials: G
authors.lastname: Bepler
authors.forename: Sauveur-Michel
authors.initials: SM
authors.lastname: Maira
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hackl
authors.forename: Robert
authors.initials: R
authors.lastname: Camp
authors.forename: Harriet M
authors.initials: HM
authors.lastname: Kluger
authors.forename: Herta H
authors.initials: HH
authors.lastname: Chao
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D058543:Class Ia Phosphatidylinositol 3-Kinase / Q000378:metabolism*; D004357:Drug Synergism; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D046888:Tissue Array Analysis
chemical_list: D000970:Antineoplastic Agents; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; C546842:MTOR protein, human; D058543:Class Ia Phosphatidylinositol 3-Kinase; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases