title: Single amino-acid changes that confer constitutive activation of mTOR are discovered in human cancer.
abstract: Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that regulates a variety of cellular functions such as growth, proliferation and autophagy. In a variety of cancer cells, overactivation of mTOR has been reported. In addition, mTOR inhibitors, such as rapamycin and its derivatives, are being evaluated in clinical trials as anticancer drugs. However, no active mutants of mTOR have been identified in human cancer. Here, we report that two different point mutations, S2215Y and R2505P, identified in human cancer genome database confer constitutive activation of mTOR signaling even under nutrient starvation conditions. S2215Y was identified in large intestine adenocarcinoma whereas R2505P was identified in renal cell carcinoma. mTOR complex 1 prepared from cells expressing the mutant mTOR after nutrient starvation still retains the activity to phosphorylate 4E-BP1 in vitro. The cells expressing the mTOR mutant show increased percentage of S-phase cells and exhibit resistance to cell size decrease by amino-acid starvation. The activated mutants are still sensitive to rapamycin. However, they show increased resistance to 1-butanol. Our study points to the idea that mTOR activating mutations can be identified in a wide range of human cancer.
authors.affiliation: Department of Microbiology, Immunology & Molecular Genetics, Molecular Biology Institute, Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA, USA.
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.forename: A
authors.initials: A
authors.lastname: Nakashima
authors.forename: L
authors.initials: L
authors.lastname: Guo
authors.forename: K
authors.initials: K
authors.lastname: Coffman
authors.forename: F
authors.initials: F
authors.lastname: Tamanoi
mesh_terms: D020001:1-Butanol / Q000494:pharmacology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000502:physiology*; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D009369:Neoplasms / Q000473:pathology*; D010766:Phosphorylation; D017354:Point Mutation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000502:physiology*; D011506:Proteins; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D013329:Structure-Activity Relationship; D058570:TOR Serine-Threonine Kinases; D014157:Transcription Factors / Q000502:physiology; D020687:cdc25 Phosphatases / Q000502:physiology
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; D011506:Proteins; D014157:Transcription Factors; D020001:1-Butanol; C546842:MTOR protein, human; D000076222:Mechanistic Target of Rapamycin Complex 1; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; C448901:ribosomal protein S6 kinase, 70kD, polypeptide 1; C517004:CDC25A protein, human; D020687:cdc25 Phosphatases; D020123:Sirolimus