Design, synthesis and structure-activity relationship of a focused library of β-phenylalanine derivatives as novel eEF2K inhibitors with apoptosis-inducing mechanisms in breast cancer

Eukaryotic elongation factor 2 kinase (eEF2K) is a Ca2+/calmudulin-dependent protein kinase, belonging to a small family of an atypical Ser/Thr-protein kinase. eEF2K has been recently reported to be highly activated or overexpressed in many types of cancer; therefore, eEF2K would be regarded as a promising therapeutic target. In this study, we discovered a beta-phenylalanine scaffold by virtual high-throughput screening, as well as designed and synthesized 46 derivatives with assessment of inhibition activity against eEF2K and cytotoxicity. After several rounds of kinase and anti-proliferative activity screening, we discovered an eEF2K inhibitor (211) with best eEF2K enzymatic activity (IC50 of 5.5 mu M) and anti proliferative activity (MDA-MB-231 cells, IC50 of 12.6 mu M, MDA-MB-436 cells, IC50 of 19.8 mu M). Moreover, we found that 211 could induce cell death via the apoptotic pathways in MDA-MB-231 and MDA-MB-436 cells. Subsequently, we evaluated its anti-tumor activity and apoptosis-inducing mechanisms in vivo. These results suggested that 211 inhibited tumor growth by apoptosis in the xenograft mouse model of breast cancer (MDA-MB-231 and MDA-MB-436). Collectively, our results demonstrate a novel small-molecule inhibitor targeting eEF2K with mechanism of apoptosis and a therapeutic potential in breast cancer. (C) 2017 Elsevier Masson SAS. All rights reserved.