title: Mammalian target of rapamycin as a therapeutic target in leukemia.
abstract: Reflecting its critical role in integrating cell growth and division with the cellular nutritional environment, the mammalian target of rapamycin *(mTOR) is a highly conserved downstream effector of the phosphatidylinositol 3-kinase (PI3K)/Akt (protein kinase B) signaling pathway. mTOR activates both the 40S ribosomal protein S6 kinase (p70s6k) and the eukaryotic initiation factor 4E-binding protein-1. As a consequence of inhibiting its downstream messengers, mTOR inhibitors prevent cyclin-dependent kinase (CDK) activation, inhibit retinoblastoma protein phosphorylation, and accelerate the turnover of cyclin D1, leading to a deficiency of active CDK4/cyclin D1 complexes, all of which may help cause GI phase arrest. Constitutive activation of the PI3K/Akt kinases occur in human leukemias. FLT3, VEGF, and BCR-ABL mediate their activities via mTOR. New rapamycin analogs including CCI-779, RAD001, and AP23573, are entering clinical studies for patients with hematologic malignancies.
authors.affiliation: Department of Leukemia, The University of Texas, M.D. Anderson Cancer Center, Houston, TX 77030, USA. fgiles@mdanderson.org
authors.forename: Francis J
authors.initials: FJ
authors.lastname: Giles
authors.forename: Maher
authors.initials: M
authors.lastname: Albitar
mesh_terms: D000068338:Everolimus; D019337:Hematologic Neoplasms / Q000378:metabolism; D006801:Humans; D007938:Leukemia / Q000188:drug therapy* / Q000378:metabolism*; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020123:Sirolimus / Q000031:analogs & derivatives / Q000494:pharmacology / Q000627:therapeutic use; D013379:Substrate Specificity; D058570:TOR Serine-Threonine Kinases
chemical_list: C401859:temsirolimus; D000068338:Everolimus; D011494:Protein Kinases; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus