title: ATP-site binding inhibitor effectively targets mTORC1 and mTORC2 complexes in glioblastoma.
abstract: The PI3K-AKT-mTOR signaling axis is central to the transformed phenotype of glioblastoma (GBM) cells, due to frequent loss of tumor suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10). The mechanistic target of rapamycin (mTOR) kinase is present in two cellular multi-protein complexes, mTORC1 and mTORC2, which have distinct subunit composition, substrates and mechanisms of action. Targeting the mTOR protein is a promising strategy for GBM therapy. However, neither of these complexes is fully inhibited by the allosteric inhibitor of mTOR, rapamycin or its analogs. Herein, we provide evidence that the combined inhibition of mTORC1/2, using the ATP-competitive binding inhibitor PP242, would effectively suppress GBM growth and dissemination as compared to an allosteric binding inhibitor of mTOR. GBM cells treated with PP242 demonstrated significantly decreased activation of mTORC1 and mTORC2, as shown by reduced phosphorylation of their substrate levels, p70 S6K(Thr389) and AKT(Ser473), respectively, in a dose-dependent manner. Furthermore, insulin induced activation of these kinases was abrogated by pretreatment with PP242 as compared with rapamycin. Unlike rapamycin, PP242 modestly activates extracellular regulated kinase (ERK1/2), as shown by expression of pERK(Thr202/Tyr204). Cell proliferation and S-phase entry of GBM cells was significantly suppressed by PP242, which was more pronounced compared to rapamycin treatment. Lastly, PP242 significantly suppressed the migration of GBM cells, which was associated with a change in cellular behavior rather than cytoskeleton loss. In conclusion, these results underscore the potential therapeutic use of the PP242, a novel ATP-competitive binding inhibitor of mTORC1/2 kinase, in suppression of GBM growth and dissemination.
authors.affiliation: Department of Neurosurgery, New York Medical College, Valhalla, NY 10595, USA.
authors.forename: Jayson
authors.initials: J
authors.lastname: Neil
authors.affiliation: Department of Neurosurgery, New York Medical College, Valhalla, NY 10595, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Shannon
authors.affiliation: Department of Neurosurgery, New York Medical College, Valhalla, NY 10595, USA.
authors.forename: Avinash
authors.initials: A
authors.lastname: Mohan
authors.affiliation: Department of Neurosurgery, New York Medical College, Valhalla, NY 10595, USA.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Laurent
authors.affiliation: Department of Neurosurgery, New York Medical College, Valhalla, NY 10595, USA.
authors.forename: Raj
authors.initials: R
authors.lastname: Murali
authors.affiliation: Department of Neurosurgery, New York Medical College, Valhalla, NY 10595, USA.
authors.forename: Meena
authors.initials: M
authors.lastname: Jhanwar-Uniyal
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D001667:Binding, Competitive; D001932:Brain Neoplasms / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D002470:Cell Survival; D002633:Chemotaxis; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005909:Glioblastoma / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000737:chemistry; D007328:Insulin / Q000737:chemistry; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D046912:Multiprotein Complexes / Q000378:metabolism*; D010641:Phenotype; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D011687:Purines / Q000737:chemistry; D016196:S Phase; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000737:chemistry; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D007211:Indoles; D007328:Insulin; D046912:Multiprotein Complexes; D011687:Purines; D000255:Adenosine Triphosphate; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D058570:TOR Serine-Threonine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; C572919:PP242; D020123:Sirolimus