Design and synthesis of EphB2 kinase inhibitors

Abstract

Erythropoietin-producing hepatocellular (Eph) receptors are known to be the largest receptor tyrosine kinases (RTKs) family and usually overexpress in diverse cancer cells. One of the Eph receptors, EphB2, was found to be upregulated in liver cancer stem cells (CSCs) which showed higher tumorigenicity compared with EphB2-suppressed cells. EphB2 receptors activate in binding with ephrin ligands to undergo dimerization of two Eph-ephrin dimers and transphosphorylation for intracellular signaling. Thus, inhibition of EphB2 activation would be a potential target for tumor suppression. Compound JFD02181(JF)was discovered to be a potent inhibitor of EphB2 by virtual screening using mini-Maybridge compound library. It showed good inhibitory activity in the kinase assay and acted as the hit compound for further research. From the preliminary structure-activity relationship (SAR) of JF analogs, a series of JF derivatives were synthesized. Some JF derivatives demonstrated good inhibitory activity, including EP003, EP019, and EP022, with cytotoxicity (CC50) of around 14­-16 µM. In the cell-based kinase assay against Huh7 EphB2 overexpressed cells, EP003 showed superior inhibitory activity compared with JF compounds. For further studies of SAR, EP003 and EP022 were selected for modifications and to probe for new binding regions of EphB2.