Abstract 2165: Structure activity relationship of a novel chemical class of Dyrk inhibitors.

Abstract

Dual-specificity tyrosine-phosphorylated and regulated kinases (DYRK) is a family of conserved protein kinases which mediate survival and differentiation in normal tissues like skeletal muscle for Mirk/Dyrk1B or neuronal cells for Dyrk1A. Among the five Dyrk proteins, Mirk/Dyrk1B has very low level of expression in most normal cell types but has been found to be upregulated in solid tumors and to mediate cell survival in colon cancer, pancreatic ductal adenocarcinoma, rhabdomyosarcomas, lung and ovarian cancer. Mirk/Dyrk1B expression and abundance varies during the cell cycle with the highest levels found in quiescent G0 phase where it mediates G0 tumor cells prolonged survival (through increasing expression of a cohort of antioxidant genes). Dyrk1A also promotes quiescence and senescence through DREAM complex assembly by phosphorylating the DREAM subunit LIN52. The ability of cells to exit from the cell cycle and enter into the G0 or quiescence state is important for cell differentiation, tissue development, and prevention of tumorigenesis. Tumors may contain a fraction of quiescent cells responsible for resistance to chemotherapy and radiation, serving as a reservoir for tumor repopulation post-therapy. Thus, pharmacological Dyrk inhibition would reduce the ability of cells to enter into quiescence and sensitize cancer cells to conventional chemotherapeutic agents. Exonhit has developed a novel class of DYRK inhibitors. Lead optimization led to the synthesis of new chemical entities with subnanomolar kinase inhibitory activities associated with a high degree of selectivity over 400 kinases. Most active compounds were evaluated in various cellular models, demonstrating good correlation between cellular activity and amplification/expression of Mirk/Dyrk1B. Similarly, in accordance with the expression levels of Mirk/Dyrk1B during the cell cycle, cellular potency of pharmacological inhibitors was improved 3 to 11 fold in SW620 quiescent cultures when compared to cycling cultures. We analyzed the effects of Dyrk inhibitors alone and in combination with gemcitabine in the Panc1 pancreatic cancer cell line multicellular tumor spheroid model described to be largely quiescent and enriched in Mirk/Dyrk1B kinase and confirmed that Dyrk inhibitors sensitize cells to gemcitabine with a synergistic effect of the combination. Among the 120 NCEs from this series, we identified lead compounds having potent in vitro efficacy as Dyrk inhibitors. These compounds are being further characterized in various cellular studies and show promising in vivo activities in patient-derived ovarian cancer ascites spheroids and Panc1 xenografts model without detectable toxicity in mice, establishing the usefulness of these inhibitors for targeting cancer cells with high Dyrk kinase activity. Citation Format: Anne-Sophie Casagrande, Florence Bachelot, Séverine Coutadeur, Bertrand Leblond, Thierry Besson, Matthew P. Pando, Laurent Désiré. Structure activity relationship of a novel chemical class of Dyrk inhibitors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2165. doi:10.1158/1538-7445.AM2013-2165

Design and Synthesis of Thiazolo[5,4-f]quinazolines as DYRK1A Inhibitors, Part II

“…The kinase selectivity profile of EHT 5372 ( 8c ) has been performed and a high degree of selectivity for DYRK1A/1B and over 339 kinases was observed [29]. These results will be further discussed together with the potential of EHT 5372 ( 8c ) to inhibit in vitro DYRK1A-induced Tau phosphorylation, Aβ production and Aβ effects on phospho-Tau.…”

Mirk kinase inhibition blocks the in vivo growth of pancreatic cancer cells

“…EHT5372 showed selective inhibitory effect on Mirk protein in a screen of over 300 protein kinases [ 20 ]. However, how much of the growth inhibitory effect on Panc1 cells was due to targeting Mirk, and not off-target kinases?…”

“…EHT5372 at 1μM was a stable compound in a human liver microsome study, with 77.4% of the drug remaining after 60 min, with a half-life of over 120 min as assayed by LC-MS [ 20 ]. EHT5372 had an IC50 of 0.28nM on the synthetic peptide substrate Dyrktide, and was highly selective in a screen of 339 kinases, including members of the dyrk family [ 20 ]. The Chk1 inhibitor LY2603618 and the mTOR inhibitor RAD001 were purchased from Selleck Chemicals.…”

Mirk/dyrk1B kinase is upregulated following inhibition of mTOR

“…Mirk inhibitors EHT 6840 and EHT 5372 were from Diaxonhit SA (Paris, France). EHT 6840 and EHT 5372 bind to the adenosine triphosphate binding site of Mirk/dyrk1B and had IC 50 values on the synthetic polypeptide Dyrktide of 0.59 nM and 0.28 nM, respectively, and were highly selective within a screen of 400 kinases ( 23 ). All pancreatic ductal adenocarcinoma cell lines and ovarian cancer cell lines were obtained from the American-Type Culture Collection and confirmed negative for mycoplasma in 2011.…”