Discovery of a Small-Molecule Bromodomain-Containing Protein 4 (BRD4) Inhibitor That Induces AMP-Activated Protein Kinase-Modulated Autophagy-Associated Cell Death in Breast Cancer

• Published in: Journal of medicinal chemistry 2017-12, Vol.60 (24), p.9990-10012
• Main Authors: Ouyang, Liang, Zhang, Lan, Liu, Jie, Fu, Leilei, Yao, Dahong, Zhao, Yuqian, Zhang, Shouyue, Wang, Guan, He, Gu, Liu, Bo
• Format: Article
• Language: English
• Subjects: AMP-Activated Protein Kinases - metabolism; Animals; Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacology; Autophagy - drug effects; Breast Neoplasms - drug therapy; Breast Neoplasms - pathology; Cell Line, Tumor; Crystallography, X-Ray; Drug Screening Assays, Antitumor; Embryo, Nonmammalian - drug effects; Female; Humans; Mice, Inbred BALB C; Molecular Docking Simulation; Nuclear Proteins - antagonists & inhibitors; Nuclear Proteins - chemistry; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Small Molecule Libraries - chemistry; Small Molecule Libraries - pharmacology; Structure-Activity Relationship; Transcription Factors - antagonists & inhibitors; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism; Xenograft Model Antitumor Assays; Zebrafish - embryology; Zebrafish - genetics
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/acs.jmedchem.7b00275

Upon the basis of The Cancer Genome Atlas (TCGA) data set, we identified that several autophagy-related proteins such as AMP-activated protein kinase (AMPK) were remarkably downregulated in breast cancer. Combined with coimmuno­precipitation assay, we demonstrated that BRD4 might interact with AMPK. After analyses of the pharmacophore and WPF interaction optimization, we designed a small-molecule inhibitor of BRD4, 9f (FL-411) which was validated by cocrystal structure with BD1 of BRD4. Subsequently, 9f was discovered to induce ATG5-dependent autophagy-associated cell death (ACD) by blocking BRD4-AMPK interaction and thus activating AMPK-mTOR-ULK1-modulated autophagic pathway in breast cancer cells. Interestingly, the iTRAQ-based proteomics analyses revealed that 9f induced ACD pathways involved in HMGB1, VDAC1/2, and eEF2. Moreover, 9f displayed a therapeutic potential on both breast cancer xenograft mouse and zebrafish models. Together, these results demonstrate that a novel small-molecule inhibitor of BRD4 induces BRD4-AMPK-modulated ACD in breast cancer, which may provide a candidate drug for future cancer therapy.