Design, synthesis, and biological evaluation of tetrahydroquinolin derivatives as potent inhibitors of CBP bromodomain

CREB-binding protein (CBP) is a large multi-domain protein containing a HAT domain catalyzing transacety-lation and a bromodomain responsible for acetylated lysine recognition. CBPs could act as transcription co-activators to regulate gene expression and have been shown to play a significant role in the development and progression of many cancers. Herein, through in silico screening two hit compounds with tetrahydroquinolin methyl carbamate scaffold were discovered, among which DC-CPin7 showed an in vitro inhibitory activity with the TR-FRET IC50 value of 2.5 +/- 0.3 mu M. We obtained a high-resolution co-crystal structure of the CBP bro-modomain in complex with DC-CPin7 to guide following structure-based rational drug design, which yielded over ten DC-CPin7 derivatives with much higher potency, among which DC-CPin711 showed approximately 40-fold potency compared with hit compound DC-CPin7 with an in vitro TR-FRET IC50 value of 63.3 +/- 4.0 nM. Notably, DC-CPin711 showed over 150-fold selectivity against BRD4 bromodomains. Moreover, DC-CPin711 showed micromolar level of anti-leukemia proliferation through G1 phase cell cycle arrest and cell apoptosis. In summary, through a combination of computational and crystal-based structure optimization, DC-CPin711 showed potent in vitro inhibitory activities to CBP bromodomain with a decent selectivity towards BRD4 bro-modomains and good cellular activity to leukemia cells, which could further be applied to related biological and translational studies as well as serve as a lead compound for future development of potent and selective CBP bromodomain inhibitors.