Design, synthesis, and biological evaluation of quinazolin-4(3H)-one derivatives co-targeting poly (ADP-ribose) polymerase-1 and bromodomain containing protein 4 for breast cancer therapy

This study was aimed to design the first dual-target small-molecule inhibitor co-targeting poly(ADP-ribose)polymerase-1(PARP1)and bromodomain containing protein 4(BRD4),which had important cross relation in the global network of breast cancer,reflecting the synthetic lethal effect.A series of new BRD4 and PARP1 dual-target inhibitors were discovered and synthesized by fragmentbased combinatorial screening and activity assays that together led to the chemical optimization.Among these compounds,19 d was selected and exhibited micromole enzymatic potencies against BRD4 and PARP1,respectively.Compound 19 d was further shown to efficiently modulate the expression of BRD4 and PARP1.Subsequently,compound 19 d was found to induce breast cancer cell apoptosis and stimulate cell cycle arrest at G1 phase.Following pharmacokinetic studies,compound 19 d showed its antitumor activity in breast cancer susceptibility gene 1/2(BRCA1/2)wild-type MDA-MB-468 and MCF-7 xenograft models without apparent toxicity and loss of body weight.These results together demonstrated that a highly potent dual-targeted inhibitor was successfully synthesized and indicated that co-targeting of BRD4 and PARP1 based on the concept of synthetic lethality would be a promising therapeutic strategy for breast cancer.