title: Biochemical, cellular, and in vivo activity of novel ATP-competitive and selective inhibitors of the mammalian target of rapamycin.
abstract: The mammalian target of rapamycin (mTOR) is centrally involved in cell growth, metabolism, and angiogenesis. While showing clinical efficacy in a subset of tumors, rapamycin and rapalogs are specific and allosteric inhibitors of mTOR complex 1 (mTORC1), but they do not directly inhibit mTOR complex 2 (mTORC2), an emerging player in cancer. Here, we report chemical structure and biological characterization of three pyrazolopyrimidine ATP-competitive mTOR inhibitors, WAY-600, WYE-687, and WYE-354 (IC(50), 5-9 nmol/L), with significant selectivity over phosphatidylinositol 3-kinase (PI3K) isofoms (>100-fold). Unlike the rapalogs, these inhibitors acutely blocked substrate phosphorylation by mTORC1 and mTORC2 in vitro and in cells in response to growth factor, amino acids, and hyperactive PI3K/AKT. Unlike the inhibitors of PI3K or dual-pan PI3K/mTOR, cellular inhibition of P-S6K1(T389) and P-AKT(S473) by the pyrazolopyrimidines occurred at significantly lower inhibitor concentrations than those of P-AKT(T308) (PI3K-PDK1 readout), showing mTOR selectivity in cellular setting. mTOR kinase inhibitors reduced AKT downstream function and inhibited proliferation of diverse cancer cell lines. These effects correlated with a strong G(1) cell cycle arrest in both the rapamycin-sensitive and rapamycin-resistant cells, selective induction of apoptosis, repression of global protein synthesis, and down-regulation of angiogenic factors. When injected into tumor-bearing mice, WYE-354 inhibited mTORC1 and mTORC2 and displayed robust antitumor activity in PTEN-null tumors. Together, our results highlight mechanistic differentiation between rapalogs and mTOR kinase inhibitors in targeting cancer cell growth and survival and provide support for clinical development of mTOR kinase inhibitors as new cancer therapy.
authors: Discovery Oncology, Wyeth Research, Pearl River, New York 10965, USA. yuk@wyeth.com
authors: Ker
authors: K
authors: Yu
authors: Lourdes
authors: L
authors: Toral-Barza
authors: Celine
authors: C
authors: Shi
authors: Wei-Guo
authors: WG
authors: Zhang
authors: Judy
authors: J
authors: Lucas
authors: Boris
authors: B
authors: Shor
authors: Jamie
authors: J
authors: Kim
authors: Jeroen
authors: J
authors: Verheijen
authors: Kevin
authors: K
authors: Curran
authors: David J
authors: DJ
authors: Malwitz
authors: Derek C
authors: DC
authors: Cole
authors: John
authors: J
authors: Ellingboe
authors: Semiramis
authors: S
authors: Ayral-Kaloustian
authors: Tarek S
authors: TS
authors: Mansour
authors: James J
authors: JJ
authors: Gibbons
authors: Robert T
authors: RT
authors: Abraham
authors: Pawel
authors: P
authors: Nowak
authors: Arie
authors: A
authors: Zask
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D042501:Angiogenic Proteins / Q000037:antagonists & inhibitors; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001667:Binding, Competitive; D045744:Cell Line, Tumor / Q000378:metabolism; D015536:Down-Regulation; D016193:G1 Phase / Q000187:drug effects; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D047428:Protein Kinase Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D011494:Protein Kinases; D011506:Proteins; D011687:Purines / Q000378:metabolism / Q000494:pharmacology*; D011720:Pyrazoles / Q000378:metabolism / Q000494:pharmacology*; D011743:Pyrimidines / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D042501:Angiogenic Proteins; C493245:CRTC2 protein, human; D046912:Multiprotein Complexes; D047428:Protein Kinase Inhibitors; D011506:Proteins; D011687:Purines; D011720:Pyrazoles; D011743:Pyrimidines; D014157:Transcription Factors; C000614249:WYE-354; D000255:Adenosine Triphosphate; D011494:Protein Kinases; C546842:MTOR protein, human; C546843:mTOR protein, mouse; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus