Wang Yinan, Yang Chuanhe, Miranda-Carboni Gustavo A, Kelso Hannah, Seetharaman Jayaraman, Hwang Dong-Jin, Miller Duane D, Pfeffer Lawrence M
Department of Pathology and Laboratory Medicine, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
Department of Medicine, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
J Cell Mol Med. 2025 Mar;29(6):e70518. doi: 10.1111/jcmm.70518.
BRG1 and BRM are subunits of the SWI/SNF chromatin remodelling complex, which has DNA-stimulated ATPase activity and can destabilise histone-DNA interactions. Targeting SWI/SNF is beneficial for treating various tumours, including glioblastoma (GBM). Our research focussed on BRG1 due to its overexpression in GBM. We developed IV-255, a selective bromodomain (BRD) inhibitor that binds to BRG1 but not BRM. IV-255 sensitised GBM cells to temozolomide (TMZ), the standard GBM treatment. We identified the binding site of IV-255 within the BRG1 BRD and found that the Tyr1497 residue is crucial for IV-255's effect on TMZ-induced GBM cell death, while Asn1540 is not. Structural analyses confirmed that Tyr1497 is involved in the IV-255 binding pocket. Mechanistically, IV-255 increases γH2AX staining in GBM cell nuclei in response to TMZ, indicating an impaired DNA double-strand break response dependent on Tyr1497. IV-255 also sensitised GBM cells to TMZ-induced apoptosis, as shown by PARP and caspase-3 cleavage, which also requires Tyr1497. In conclusion, Tyr1497 within the BRD of BRG1 is critical for its interaction with IV-255 and for sensitising GBM cells to TMZ-induced DNA double-strand breaks and apoptotic cell death.
BRG1和BRM是SWI/SNF染色质重塑复合物的亚基，该复合物具有DNA刺激的ATP酶活性，能够破坏组蛋白与DNA的相互作用。靶向SWI/SNF对治疗包括胶质母细胞瘤（GBM）在内的各种肿瘤有益。由于BRG1在GBM中过表达，我们的研究聚焦于BRG1。我们开发了IV-255，一种选择性溴结构域（BRD）抑制剂，它能与BRG1结合但不与BRM结合。IV-255使GBM细胞对替莫唑胺（TMZ）（GBM的标准治疗药物）敏感。我们确定了IV-255在BRG1的BRD内的结合位点，发现Tyr1497残基对于IV-255对TMZ诱导的GBM细胞死亡的作用至关重要，而Asn1540并非如此。结构分析证实Tyr1497参与了IV-255结合口袋。从机制上讲，IV-255会使GBM细胞核中γH2AX染色增加以响应TMZ，这表明依赖于Tyr1497的DNA双链断裂反应受损。IV-255还使GBM细胞对TMZ诱导的凋亡敏感，如PARP和caspase-3的切割所示，这也需要Tyr1497。总之，BRG1的BRD内的Tyr1497对于其与IV-25
