Peptide Inhibitor Targeting the Extraterminal Domain in BRD4 Potently Suppresses Breast Cancer Both In Vitro and In Vivo

• Published in: Journal of medicinal chemistry 2024-04, Vol.67 (8), p.6658-6672
• Main Authors: Huang, Qi-xuan, Fan, Da-meng, Zheng, Zao-zao, Ran, Ting, Bai, Ao, Xiao, Rong-quan, Hu, Guo-sheng, Liu, Wen
• Format: Article
• Language: English
• Subjects: Animals; Antineoplastic Agents - chemical synthesis; Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacology; Breast Neoplasms - drug therapy; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Bromodomain Containing Proteins; Cell Cycle Proteins - antagonists & inhibitors; Cell Cycle Proteins - metabolism; Cell Line, Tumor; Cell Proliferation - drug effects; Female; Humans; Mice; Mice, Nude; Nuclear Proteins - antagonists & inhibitors; Nuclear Proteins - metabolism; Peptides - chemistry; Peptides - pharmacology; Protein Domains; Transcription Factors - antagonists & inhibitors; Transcription Factors - metabolism
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/acs.jmedchem.4c00141

BRD4 is associated with a variety of human diseases, including breast cancer. The crucial roles of amino-terminal bromodomains (BDs) of BRD4 in binding with acetylated histones to regulate oncogene expression make them promising drug targets. However, adverse events impede the development of the BD inhibitors. BRD4 adopts an extraterminal (ET) domain, which recruits proteins to drive oncogene expression. We discovered a peptide inhibitor PiET targeting the ET domain to disrupt BRD4/JMJD6 interaction, a protein complex critical in oncogene expression and breast cancer. The cell-permeable form of PiET, TAT-PiET, and PROTAC-modified TAT-PiET, TAT-PiET-PROTAC, potently inhibits the expression of BRD4/JMJD6 target genes and breast cancer cell growth. Combination therapy with TAT-PiET/TAT-PiET-PROTAC and JQ1, iJMJD6, or Fulvestrant exhibits synergistic effects. TAT-PiET or TAT-PiET-PROTAC treatment overcomes endocrine therapy resistance in ERα-positive breast cancer cells. Taken together, we demonstrated that targeting the ET domain is effective in suppressing breast cancer, providing a therapeutic avenue in the clinic.