title: Involvement of mTOR signaling pathways in regulating growth and dissemination of metastatic brain tumors via EMT.
abstract: BACKGROUND
  Metastatic dissemination to the brain may involve a process termed epithelial-mesenchymal transition (EMT), which results in a migratory, invasive and proliferative cell phenotype. Recent studies suggest that Mechanistic target of rapamycin (mTOR, that exists in two multi-protein complexes (mTORC1 and mTORC2), may regulate EMT, in addition to controlling cell growth, survival, metabolism and motility. However, the role of mTOR in brain metastases remains elusive. We hypothesize that mTOR plays a crucial role in the process of EMT in brain metastasis and therefore serves as a target of therapy.
  
  
  METHODS
  Immunohistochemical analyses were performed to determine the expression of components of mTOR pathways. Immunofluorescence and immunoblotting were executed to determine the markers of EMT after treatments with siRNA or inhibitors of mTOR pathways. Cell proliferation using MTT, S-phase entry by determining EdU-incorporation, chemotactic and scratch-wound migration assays were performed.
  
  
  RESULTS
  Metastatic tumor samples expressed components of mTOR pathways, namely, mTOR, Raptor and Rictor with a significant overlap. Metastatic potential was enhanced in an astrocytic environment and suppressed following mTOR inhibition. mTOR inhibition resulted in nuclear localization of the epithelial marker of EMT, E-cadherin, and enhancement in expression of the mesenchymal marker vimentin.
  
  
  CONCLUSIONS
  Results suggest that the mTOR pathway is activated in metastatic brain tumors, and inhibition of mTOR signaling could provide therapeutic value in the management of patients with brain metastases.
authors: Department of Neurosurgery, New York Medical College, Valhalla, NY, U.S.A.
authors: Amanda
authors: A
authors: Kwasnicki
authors: Department of Neurosurgery, New York Medical College, Valhalla, NY, U.S.A.
authors: Dhruve
authors: D
authors: Jeevan
authors: Department of Pathology, New York Medical College, Valhalla, NY, U.S.A.
authors: Alex
authors: A
authors: Braun
authors: Department of Neurosurgery, New York Medical College, Valhalla, NY, U.S.A.
authors: Raj
authors: R
authors: Murali
authors: Department of Neurosurgery, New York Medical College, Valhalla, NY, U.S.A. meena_jhanwar@nymc.edu.
authors: Meena
authors: M
authors: Jhanwar-Uniyal
mesh_terms: D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000378:metabolism; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology*; D002455:Cell Division; D017931:DNA Primers; D058750:Epithelial-Mesenchymal Transition; D005455:Fluorescent Antibody Technique; D006801:Humans; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D046912:Multiprotein Complexes / Q000378:metabolism*; D009362:Neoplasm Metastasis; D034741:RNA, Small Interfering; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D017931:DNA Primers; D046912:Multiprotein Complexes; D034741:RNA, Small Interfering; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D058570:TOR Serine-Threonine Kinases
keywords: EMT; brain metastases; mTOR; mTORC1; mTORC2