Disrupting the Interaction of BRD4 with Diacetylated Twist Suppresses Tumorigenesis in Basal-like Breast Cancer

• Twist contains a “histone H4-mimic” GK-X-GK motif that is diacetylated by Tip60
• BRD4 forms a bivalent link with acetylated H4 at BD1 and diacetylated Twist at BD2
• The Twist-BRD4 complex controls WNT5A expression in EMT and basal-like breast cancer
• BET inhibitors suppress tumorigenicity by disrupting the Twist-BRD4 interaction

SummaryTwist is a key transcription activator of epithelial-mesenchymal transition (EMT). It remains unclear how Twist induces gene expression. Here we report a mechanism by which Twist recruits BRD4 to direct WNT5A expression in basal-like breast cancer (BLBC). Twist contains a “histone H4-mimic” GK-X-GK motif that is diacetylated by Tip60. The diacetylated Twist binds the second bromodomain of BRD4, whose first bromodomain interacts with acetylated H4, thereby constructing an activated Twist/BRD4/P-TEFb/RNA-Pol II complex at the WNT5A promoter and enhancer. Pharmacologic inhibition of the Twist-BRD4 association reduced WNT5A expression and suppressed invasion, cancer stem cell (CSC)-like properties, and tumorigenicity of BLBC cells. Our study indicates that the interaction with BRD4 is critical for the oncogenic function of Twist in BLBC.