title: Targeting the PI3K/PTEN/AKT/mTOR Pathway in Treatment of Sarcoma Cell Lines.
abstract: Sarcoma carries a poor prognosis prompting the need for targeted therapies aimed at deregulated signaling pathways. These include the PI3K/Akt/mTOR pathway commonly up-regulated in malignancies attributed to loss of PTEN expression. However, PTEN status and activation state of PI3K/Akt/mTOR pathway have not been comprehensively studied in sarcoma. The aims of this study were to characterise PTEN and Akt expression in a panel of sarcoma cell lines and then to examine mTOR inhibition using ridaforolimus.
  
  
  
  PTEN genomic expression was analyzed using Sanger sequencing. PTEN, total Akt (tAkt) and phosphorylated Akt (pAkt) expression were quantified with western blot analysis. Antiproliferative effects of treatment regimens were designed using Chou & Talalay's isobologram and determined with crystal violet assay.
  
  
  
  Four cell lines had wild-type PTEN (exons 2 to 8), with normal protein expression. The GCT cell line had a missense mutation in exon 6 (C>T), associated with loss of PTEN protein expression. Increased pAkt expression was found in all cell lines following epidermal growth factor (EGF) stimulation, indicating that wild-type PTEN expression in four cell lines did not inhibit constitutive activation of PI3K/Akt/mTOR pathway. Nonetheless, all cell lines demonstrated sensitivity to ridaforolimus within a clinically relevant dose-range (half-maximal inhibitory concentration (IC50)=0.7-10 nM).
  
  
  
  PTEN mutation is rare in sarcoma cell lines and constitutive activation of PI3K/Akt/mTOR is independent of PTEN status.
authors: Sarcoma and Nano-oncology Group, Adult Cancer Program, Lowy Cancer Research Centre, Department of Medical Oncology and Surgery, Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Randwick, NSW, Australia.
authors: Hui Jun
authors: HJ
authors: Lim
authors: Sarcoma and Nano-oncology Group, Adult Cancer Program, Lowy Cancer Research Centre, Department of Medical Oncology and Surgery, Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Randwick, NSW, Australia.
authors: Xiaochun
authors: X
authors: Wang
authors: Sarcoma and Nano-oncology Group, Adult Cancer Program, Lowy Cancer Research Centre, Department of Medical Oncology and Surgery, Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Randwick, NSW, Australia.
authors: Philip
authors: P
authors: Crowe
authors: Sarcoma and Nano-oncology Group, Adult Cancer Program, Lowy Cancer Research Centre, Department of Medical Oncology and Surgery, Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Randwick, NSW, Australia.
authors: David
authors: D
authors: Goldstein
authors: Sarcoma and Nano-oncology Group, Adult Cancer Program, Lowy Cancer Research Centre, Department of Medical Oncology and Surgery, Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Randwick, NSW, Australia j.yang@unsw.edu.au.
authors: Jia-Lin
authors: JL
authors: Yang
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation; D006801:Humans; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012509:Sarcoma / Q000188:drug therapy* / Q000473:pathology; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; C546842:MTOR protein, human; C494929:PTEN protein, human
keywords: PI3K/PTEN/Akt/mTOR pathway; PTEN expression; Sarcoma; targeted therapy