title: PI-103 and sorafenib inhibit hepatocellular carcinoma cell proliferation by blocking Ras/Raf/MAPK and PI3K/AKT/mTOR pathways.
abstract: BACKGROUND
  Aberrant Ras/Raf/MAPK and PI3K/AKT/mTOR signaling pathways are found in hepatocellular carcinoma (HCC). This study reports how sorafenib (a multi-kinase inhibitor) and PI-103 (a dual PI3K/mTOR inhibitor) alone and in combination inhibit the proliferation of the HCC cell line, Huh7.
  
  
  METHODS
  Huh7 proliferation was assayed by 3H-thymidine incorporation and by MTT assay. Western blot was used to detect phosphorylation of the key enzymes in the Ras/Raf and PI3K pathways.
  
  
  RESULTS
  Sorafenib and PI-103, as single agents inhibited Huh7 proliferation and epidermal growth factor (EGF)-stimulated Huh7 proliferation in a dose-dependent fashion; the combination of sorafenib and PI-103 produced synergistic effects. EGF increased phosphorylation of MEK and ERK, key Ras/Raf downstream signaling proteins; this activation was inhibited by sorafenib. However, sorafenib as a single agent increased AKT(Ser473) and mTOR phosphorylation. EGF-stimulated activation of PI3K/AKT/mTOR pathway components was inhibited by PI-103. PI-103 is a potent inhibitor of AKT(Ser473) phosphorylation; in contrast, rapamycin stimulated AKT(Ser473) phosphorylation. It was found that PI-103, as a single agent, stimulated MEK and ERK phosphorylation. However, the combination of sorafenib and PI-103 caused inhibition of all the tested kinases in the Ras/Raf and PI3K pathways.
  
  
  CONCLUSIONS
  The combination of sorafenib and PI-103 can significantly inhibit EGF-stimulated Huh7 proliferation by blocking both Ras/Raf/MAPK and PI3K/AKT/mTOR pathways.
authors.affiliation: Department of Surgery, University of Kentucky, College of Medicine, Lexington, KY 40536, USA. rgeda2@uky.edu
authors.forename: Roberto
authors.initials: R
authors.lastname: Gedaly
authors.forename: Paul
authors.initials: P
authors.lastname: Angulo
authors.forename: Jonathan
authors.initials: J
authors.lastname: Hundley
authors.forename: Michael F
authors.initials: MF
authors.lastname: Daily
authors.forename: Changguo
authors.initials: C
authors.lastname: Chen
authors.forename: Alvaro
authors.initials: A
authors.lastname: Koch
authors.forename: B Mark
authors.initials: BM
authors.lastname: Evers
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D001557:Benzenesulfonates / Q000008:administration & dosage / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005663:Furans / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009536:Niacinamide / Q000031:analogs & derivatives; D010671:Phenylurea Compounds; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D011725:Pyridines / Q000008:administration & dosage / Q000494:pharmacology*; D011743:Pyrimidines / Q000008:administration & dosage / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D000077157:Sorafenib; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D048490:raf Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D018631:ras Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D001557:Benzenesulfonates; D004815:Epidermal Growth Factor; D005663:Furans; D020928:Mitogen-Activated Protein Kinases; D009536:Niacinamide; D010671:Phenylurea Compounds; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D011725:Pyridines; D011743:Pyrimidines; D000077157:Sorafenib; D058570:TOR Serine-Threonine Kinases; D048490:raf Kinases; D018631:ras Proteins; C522973:PI103; C546842:MTOR protein, human