dBET6 is a highly cell-permeable degrader of BET bromodomains. It is potent in most cancer cell lines. dBET6 features highly increased cellular potency with evident degradation in the sub-nanomolar range. Treatment with 100 nM dBET6 leads to degradation of BRD4 after 1 hr, prompting subsequent downregulation of c-MYC and induction of apoptosis. dBET6 disrupts global productive transcription elongation. dBET6 treatment leads to a widespread decrease in steady-state mRNA levels, but observed an incommensurate impact on expression of members of the core regulatory circuitry of leukemogenic transcription factors. The collapse of the core transcriptional machinery prompted by BET degradation precedes a robust apoptotic response, of apparent translational significance.
