Design, Synthesis, And Structure-activity-relationship Of Porcupine Antagonists Led To Potent Wnt Signaling Pathway Inhibitors

Wnt signaling pathway is a highly conserved signaling pathway during embryonic development which controls cell multiplication and differentiation, and also essential for normal adult homeostasis. However, aberrant reactivation may lead to human cancers. In recent years, the Wnt signaling pathway, especially the new target Porcupine small molecule inhibitor has become a hot research topic. Some small molecule inhibitors of Porcupine have been published at present, only LGK974 and ETC-159 successfully entered phase I clinical trials. So there is still great space for the improvement of small molecule inhibitors of Porcupine.Here we designed and synthesized a novel series of compounds of which the central amide consists of a 4-atom unit by a scaffold hybridization strategy from some known porcupine inhibitors. We tested Wnt signaling inhibition of 23 compounds, and the results showed that LGK974 element on the right hand is the best structure for activity while the left fragment has a great influence on activity. Finally we got compounds 3, 19, 21, 22 and 23 with Wnt signaling inhibition activities comparable to or better than that of the clinical candidate LGK974, and demonstrated by compound 23(IC50 = 0.11 nM) which was five times potent than LGK974(IC50 = 0.57 nM) in the same assay. Compounds also potently inhibited Wnt secretion into culture medium, an indication of direct inhibition of the porcupine protein. Then we selected potent compounds 3, 19, 21, 22 and 23 to do the chemical stability, rat plasma stability and liver microsomal stability test. The results showed that these compounds have good chemical and plasma stabilities, and compounds 19 and 23 showed moderate clearance and half-life. Meanwhile these five compounds were subjected to the standard CYP inhibition test, and they showed weak CYP inhibition.Anyway, we designed and synthesized a series of compounds which have good inhibition activities and stabilities. And these results will lead us to develop better Wnt pathway inhibitors.