Design, synthesis, and biological evaluation of quinoxalinone derivatives as potent BRD4 inhibitors.

The bromodomain-containing protein 4 (BRD4) has gained growing interest as an effective drug target for the treatment of hepatocellular carcinoma (HCC). Herein, we designed and synthesized a series of quinoxalinone derivatives as BRD4 inhibitors via scaffold hopping. The representative compound X9 showed potent BRD4 inhibitory activity (with IC50 = 82.3 nM), and preferable antiproliferative activity against HepG2 cells (with IC50 = 1.13 ± 0.07 µM), as well as less toxicity against GES-1 cells (with IC50 = 57.24 ± 5.46 µM). Furthermore, compound X9 dose-dependently inhibited colony formation and blocked the migration of HepG2 cells by down-regulating the expression of Snail and MMP-9 while up-regulating the E-cadherin and Occludin. Besides, compound X9 efficiently down-regulated the expression of c-Myc in HepG2 cells, induced apoptosis, and arrested at G0/G1 phase. In total, quinoxalinone was a potential core as BRD4 inhibitor and compound X9 might be effective for liver cancer therapy.

Design, synthesis and biological evaluation of coumarin derivatives as potential BRD4 inhibitors.

The bromodomain and extra-terminal (BET) bromodomains, particularly BRD4, have been identified as promising therapeutic targets in the treatment of many human disorders such as cancer. Coumarin is a highly privileged moiety for the development of novel anticancer drugs which has been identified in clinical trials for the treatment of various cancers. Herein, we modified BRD4i ABBV-075 with a coumarin ring and synthesized a novel series of coumarin derivatives as BRD4 inhibitors. Among them, the representative compound 27d showed excellent BRD4 inhibitory activities with an IC50 value of 99 nM in the TR-FRET assay. Compared with ABBV-075, compound 27d displayed a favorable cell proliferation inhibitory activity in solid tumors, such as MCF-7, HGC-27 and HepG-2. Further mechanism investigation illustrated that 27d-treatment resulted in G0/G1 phase arrest and promoted apoptosis of MCF-7 cells. Compound 27d also blocked colony formation in a concentration-dependent manner in McF-7 cell lines. As the downstream-protein of BRD4, the expression of c-Myc was decreased in a dose-dependent manner after the treatment of compound 27d. Moreover, compound 27d also exhibited good in vivo and in vitro metabolic stability. All the findings meaningfully make it as a promising lead compound for further drug development.

Discovery of novel VEGFR-2-PROTAC degraders based on the localization of lysine residues via recruiting VHL for the treatment of gastric cancer.

VEGFR-2 is an attractive therapeutic target for antitumor drug research by blocking tumor angiogenesis and PROTAC provides a new technology for targeted protein knockout. Herein, a library of novel VEGFR-2-PROTAC degraders were rationally designed and synthesized based on the Lys residue region on the surface of VEGFR-2 protein using protein structure-based drug design strategy. Among them, P7 exhibited preferable antitumor activity against HGC-27 cells and less toxic to human normal HUVEC, HEK293T and GES-1 cells in vitro, as well as the potent degradation activity of VEGFR-2 protein in HGC-27 cells (DC50: 0.084 ± 0.04 µM, Dmax: 73.7%) and HUVEC cells (DC50: 0.51 ± 0.10 µM, Dmax: 76.6%). Additionally, P7 degraded VEGFR-2 protein by the formation of ternary complex and the ubiquitin proteasome pathway in HGC-27 cells. Furthermore, P7 shortened the half-life of VEGFR-2 protein synthesis and had no inhibitory effect on the expression of VEGFR-2 mRNA in HGC-27 cells. Moreover, P7 inhibited the colony formation, migration and invasion of HGC-27 cells in a time- and dose-dependent manner, and meanwhile induced G2/M phase cycle arrest and apoptosis. All the results demonstrated that P7 could be as a promising VEGFR-2-PROTAC degrader for gastric cancer therapy.