ABSTRACT
We report here the discovery of a novel series of selective mTOR kinase inhibitors and the identification of CC214-2, a compound with demonstrated anti-tumor activity upon oral dosing in a PC3 prostate cancer xenograft model. A series of 4,6-disubstituted-3,4-dihydropyrazino[2,3-b]pyrazine-2(1H)-ones were discovered through a core modification of our original compound series. Analogs from this series have excellent mTOR potency and maintain selectivity over the related PI3Kα lipid kinase. Compounds such as CC214-2 were found to block both mTORC1(pS6) and mTORC2(pAktS473) signaling in PC3 cancer cells, in vitro and in vivo.
Subject(s)
Antineoplastic Agents/chemistry , Protein Kinase Inhibitors/chemistry , Pyrazines/chemistry , TOR Serine-Threonine Kinases/antagonists & inhibitors , Administration, Oral , Animals , Antineoplastic Agents/pharmacokinetics , Antineoplastic Agents/therapeutic use , Cell Line, Tumor , Cell Proliferation/drug effects , Drug Evaluation, Preclinical , Half-Life , Humans , Male , Mice , Phosphatidylinositol 3-Kinases/metabolism , Phosphoinositide-3 Kinase Inhibitors , Prostatic Neoplasms/drug therapy , Prostatic Neoplasms/metabolism , Prostatic Neoplasms/pathology , Protein Kinase Inhibitors/pharmacokinetics , Protein Kinase Inhibitors/therapeutic use , Proto-Oncogene Proteins c-akt/metabolism , Pyrazines/pharmacokinetics , Pyrazines/therapeutic use , Pyrazines/toxicity , Signal Transduction/drug effects , TOR Serine-Threonine Kinases/metabolism , Transplantation, HeterologousABSTRACT
We have found that the synthetic compound CC-5079 potently inhibits cancer cell growth in vitro and in vivo by a novel combination of molecular mechanisms. CC-5079 inhibits proliferation of cancer cell lines from various organs and tissues at nanomolar concentrations. Its IC(50) value ranges from 4.1 to 50 nmol/L. The effect of CC-5079 on cell growth is associated with cell cycle arrest in G(2)-M phase, increased phosphorylation of G(2)-M checkpoint proteins, and apoptosis. CC-5079 prevents polymerization of purified tubulin in a concentration-dependent manner in vitro and depolymerizes microtubules in cultured cancer cells. In competitive binding assays, CC-5079 competes with [(3)H]colchicine for binding to tubulin; however, it does not compete with [(3)H]paclitaxel (Taxol) or [(3)H]vinblastine. Our data indicate that CC-5079 inhibits cancer cell growth with a mechanism of action similar to that of other tubulin inhibitors. However, CC-5079 remains active against multidrug-resistant cancer cells unlike other tubulin-interacting drugs, such as Taxol and colchicine. Interestingly, CC-5079 also inhibits tumor necrosis factor-alpha (TNF-alpha) secretion from lipopolysaccharide-stimulated human peripheral blood mononuclear cells (IC(50), 270 nmol/L). This inhibitory effect on TNF-alpha production is related to its inhibition of phosphodiesterase type 4 enzymatic activity. Moreover, in a mouse xenograft model using HCT-116 human colorectal tumor cells, CC-5079 significantly inhibits tumor growth in vivo. In conclusion, our data indicate that CC-5079 represents a new chemotype with novel mechanisms of action and that it has the potential to be developed for neoplastic and inflammatory disease therapy.
