title: Characterization and targeting of phosphatidylinositol-3 kinase (PI3K) and mammalian target of rapamycin (mTOR) in renal cell cancer.
abstract: BACKGROUND
  PI3K and mTOR are key components of signal transduction pathways critical for cell survival. Numerous PI3K inhibitors have entered clinical trials, while mTOR is the target of approved drugs for metastatic renal cell carcinoma (RCC). We characterized expression of p85 and p110α PI3K subunits and mTOR in RCC specimens and assessed pharmacologic co-targeting of these molecules in vitro.
  
  
  METHODS
  We employed tissue microarrays containing 330 nephrectomy cases using a novel immunofluorescence-based method of Automated Quantitative Analysis (AQUA) of in situ protein expression. In RCC cell lines we assessed synergism between PI3K and mTOR inhibitors and activity of NVP-BEZ235, which co-targets PI3K and mTOR.
  
  
  RESULTS
  p85 expression was associated with high stage and grade (P < 0.0001 for both). High p85 and high mTOR expression were strongly associated with decreased survival, and high p85 was independently prognostic on multi-variable analysis. Strong co-expression of both PI3K subunits and mTOR was found in the human specimens. The PI3K inhibitor LY294002 and rapamycin were highly synergistic in all six RCC cell lines studied. Similar synergism was seen with all rapamycin concentrations used. NVP-BEZ235 inhibited RCC cell growth in vitro with IC(50)s in the low ηM range and resultant PARP cleavage.
  
  
  CONCLUSIONS
  High PI3K and mTOR expression in RCC defines populations with decreased survival, suggesting that they are good drug targets in RCC. These targets tend to be co-expressed, and co-targeting these molecules is synergistic. NVP-BEZ235 is active in RCC cells in vitro; suggesting that concurrent PI3K and mTOR targeting in RCC warrants further investigation.
authors.affiliation: Division of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, United States of America.
authors.forename: Aymen A
authors.initials: AA
authors.lastname: Elfiky
authors.forename: Saadia A
authors.initials: SA
authors.lastname: Aziz
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Conrad
authors.forename: Summar
authors.initials: S
authors.lastname: Siddiqui
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hackl
authors.forename: Michel
authors.initials: M
authors.lastname: Maira
authors.forename: Camp L
authors.initials: CL
authors.lastname: Robert
authors.forename: Harriet M
authors.initials: HM
authors.lastname: Kluger
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001331:Automation; D014408:Biomarkers, Tumor / Q000378:metabolism; D002292:Carcinoma, Renal Cell / Q000201:enzymology* / Q000473:pathology; D045744:Cell Line, Tumor; D002867:Chromones / Q000494:pharmacology; D004357:Drug Synergism; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D007680:Kidney Neoplasms / Q000201:enzymology* / Q000473:pathology; D058990:Molecular Targeted Therapy; D009025:Morpholines / Q000494:pharmacology; D015999:Multivariate Analysis; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D002867:Chromones; D007093:Imidazoles; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D011804:Quinolines; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D058539:Phosphatidylinositol 3-Kinase; D058570:TOR Serine-Threonine Kinases; C531198:dactolisib; D020123:Sirolimus