Definition

A small molecule, chaperone-mediated protein degrader of bromodomain-containing protein 4 (BRD4), with potential antineoplastic activity. Upon intravenous administration of BRD4 protein degrader RNK05047, a BRD4-binding moiety targets and binds to BRD4, and a chaperone-binding moiety targets and binds to the chaperone protein heat shock protein 90 (Hsp90). This results in the Hsp90-mediated proteasomal degradation of BRD4 by the ubiquitin-proteasome system, and dysregulates gene expression. This may lead to the downregulation of the expression of certain growth-promoting genes, which may induce apoptosis and inhibit the proliferation of BRD4-overexpressing tumor cells. BRD4, a member of the human bromodomain and extra-terminal (BET) family of proteins, is a transcriptional regulator that is overexpressed in certain tumor cells and plays an important role in cellular proliferation. Hsp90 is upregulated in a variety of tumor cells and regulates the folding, stability, and degradation of many oncogenic signaling proteins.