**3.6 Repurposed drugs for BETs**

BET protein family, including BRD2, BRD3, BRD4, and BRDT, are readers of acetylated K residues on histones and non-histone proteins. BET inhibition is effective against kidney diseases, tumor development, cardiovascular disease, and other inflammatory diseases [106]. Some drugs have been repurposed to target BET proteins in diseases. For example, nitroxoline (**Table 1**) is an FDA-approved antibiotic and also a potent inhibitor of most BET family members. A study reported that nitroxoline significantly reduced the proliferation of leukemia cells *via* induction of apoptosis and cell cycle arrest. The anti-cancer action of nitroxoline is partly through BET inhibition and its downstream targets [93]. Another class of BET inhibitors, for example, molibresib, is a derivative of benzodiazepines, a psychoactive class of drugs used to treat neurological-related conditions. Molibresib is currently in phase I clinical trial for the treatment of multiple cancers [107]. Additionally, azelastine, an antihistamine used to treat hay fever and allergies, was ranked as one of the top drugs for having the best binding affinity to BRD4 [94]. Collectively, the aforementioned approved and putative repurposed drugs could serve as an effective BET inhibition-based therapy in different diseases.
