Discovery of Thieno[2,3- d]pyrimidine-Based Hydroxamic Acid Derivatives as Bromodomain-Containing Protein 4/Histone Deacetylase Dual Inhibitors Induce Autophagic Cell Death in Colorectal Carcinoma Cells

Bromodomain-containing protein 4 (BRD4) and histone deacetylases (HDAC) are both attractive epigenetic targets in Cancer and Other chronic diseases. Based on the integrated fragment-based drug design, synthesis, and in vitro and in vivo evaluations, a series of novel thieno[2,3-d]pyrimidine-based hydroxamic acid derivatives are discovered as selective BRD4-HDAC dual inhibitors. Compound 17c is the most potent inhibitor for BRD4 and HDAC with IC₅₀ values at nanomolar levels, as well as the expression level of c-Myc, and increases the acetylation of histone H3. Moreover, 17c presents inhibitory effects on the proliferation of colorectal carcinoma (CRC) cells via inducing autophagic cell death. It also has a good pharmacokinetic profile in rats and oral bioavailability of 40.5%. In the HCT-116 xenograft in vivo models, 17c displays potent inhibitory efficiency on tumor growth by inducing autophagic cell death and suppressing IL6-JAK-STAT signaling pathways. Our results suggest that the BRD4-HDAC dual inhibition might be an attractive therapeutic strategy for CRC.