1.Targeting primitive chronic myeloid leukemia cells by effective inhibition of a new AHI-1-BCR-ABL-JAK2 complex.
Chen M1, Gallipoli P, DeGeer D, Sloma I, Forrest DL, Chan M, Lai D, Jorgensen H, Ringrose A, Wang HM, Lambie K, Nakamoto H, Saw KM, Turhan A, Arlinghaus R, Paul J, Stobo J, Barnett MJ, Eaves A, Eaves CJ, Holyoake TL, Jiang X. J Natl Cancer Inst. 2013 Mar 20;105(6):405-23. doi: 10.1093/jnci/djt006. Epub 2013 Feb 27.
BACKGROUND: Imatinib mesylate (IM) induces clinical remission of chronic myeloid leukemia (CML). The Abelson helper integration site 1 (AHI-1) oncoprotein interacts with BCR-ABL and Janus kinase 2 (JAK2) to mediate IM response of primitive CML cells, but the effect of the interaction complex on the response to ABL and JAK2 inhibitors is unknown.
2.Dual PI3K/AKT/mTOR inhibitor BEZ235 synergistically enhances the activity of JAK2 inhibitor against cultured and primary human myeloproliferative neoplasm cells.
Fiskus W1, Verstovsek S, Manshouri T, Smith JE, Peth K, Abhyankar S, McGuirk J, Bhalla KN. Mol Cancer Ther. 2013 May;12(5):577-88. doi: 10.1158/1535-7163.MCT-12-0862. Epub 2013 Feb 27.
Hemopoietic progenitor cells (HPC) from myeloproliferative neoplasms (MPN) such as myelofibrosis commonly express mutant JAK2-V617F or other mutations that are associated with increased activities of JAK-STAT5/3, RAS/RAF/MAPK, and PI3K/AKT/mTOR pathways. This confers proliferative and survival advantage on the MPN HPCs. Treatment with JAK tyrosine kinase inhibitor (TKI), for example, TG101209, TG101348 (SAR302503), or INCB018424 (ruxolitinib), inhibits mutant JAK2-mediated signaling. Although effective in reducing constitutional symptoms and splenomegaly, treatment with JAK-TKI does not ameliorate myelofibrosis or significantly improve survival of patients with advanced myelofibrosis. Here, we show that treatment with the dual phosphoinositide-3-kinase (PI3K)/AKT and mTOR inhibitor BEZ235 attenuated PI3K/AKT and mTOR signaling, as well as induced cell-cycle growth arrest and apoptosis of the cultured human JAK2-V617F-expressing HEL92.1.7 (HEL), UKE1 cells, and primary CD34+ myelofibrosis (MF)-MPN cells.
3.JAK inhibitors suppress t(8;21) fusion protein-induced leukemia.
Lo MC1, Peterson LF, Yan M, Cong X, Hickman JH, Dekelver RC, Niewerth D, Zhang DE. Leukemia. 2013 Dec;27(12):2272-9. doi: 10.1038/leu.2013.197. Epub 2013 Jul 1.
Oncogenic mutations in components of the JAK/STAT pathway, including those in cytokine receptors and JAKs, lead to increased activity of downstream signaling and are frequently found in leukemia and other hematological disorders. Thus, small-molecule inhibitors of this pathway have been the focus of targeted therapy in these hematological diseases. We previously showed that t(8;21) fusion protein acute myeloid leukemia (AML)1-ETO and its alternatively spliced variant AML1-ETO9a (AE9a) enhance the JAK/STAT pathway via downregulation of CD45, a negative regulator of this pathway. To investigate the therapeutic potential of targeting JAK/STAT in t(8;21) leukemia, we examined the effects of a JAK2-selective inhibitor TG101209 and a JAK1/2-selective inhibitor INCB18424 on t(8;21) leukemia cells. TG101209 and INCB18424 inhibited proliferation and promoted apoptosis of these cells. Furthermore, TG101209 treatment in AE9a leukemia mice reduced tumor burden and significantly prolonged survival.
4.Acetyl-lysine binding site of bromodomain-containing protein 4 (BRD4) interacts with diverse kinase inhibitors.
Ember SW1, Zhu JY, Olesen SH, Martin MP, Becker A, Berndt N, Georg GI, Schönbrunn E. ACS Chem Biol. 2014 May 16;9(5):1160-71. doi: 10.1021/cb500072z. Epub 2014 Mar 13.
Members of the bromodomain and extra terminal (BET) family of proteins are essential for the recognition of acetylated lysine (KAc) residues in histones and have emerged as promising drug targets in cancer, inflammation, and contraception research. In co-crystallization screening campaigns using the first bromodomain of BRD4 (BRD4-1) against kinase inhibitor libraries, we identified and characterized 14 kinase inhibitors (10 distinct chemical scaffolds) as ligands of the KAc binding site. Among these, the PLK1 inhibitor BI2536 and the JAK2 inhibitor TG101209 displayed strongest inhibitory potential against BRD4 (IC50=25 nM and 130 nM, respectively) and high selectivity for BET bromodomains. Comparative structural analysis revealed markedly different binding modes of kinase hinge-binding scaffolds in the KAc binding site, suggesting that BET proteins are potential off-targets of diverse kinase inhibitors. Combined, these findings provide a new structural framework for the rational design of next-generation BET-selective and dual-activity BET-kinase inhibitors.
