Brother of regulator of imprinted sites (BORIS) is expressed in most cancers and often associated with short survival and poor prognosis in patients. BORIS inhibits apoptosis and promotes proliferation of cancer cells. However, its mechanism of action has not been elucidated, and there is no known inhibitor of BORIS. A phage display library was used to find the BORIS inhibitory peptides and BTApep-TAT was identified. The RNA sequencing profile of BTApep-TAT-treated H1299 cells was compared with that of BORIS-knockdown cells. Antitumor activity of BTApep-TAT was evaluated in a non-small cell lung cancer (NSCLC) xenograft mouse model. BTApep-TAT was also used to investigate the post-translational modification (PTM) of BORIS and the role of BORIS in DNA damage repair. Site-directed mutants of BORIS were constructed and used for investigating PTM and the function of BORIS. BTApep-TAT induced DNA damage in cancer cells and suppressed NSCLC xenograft tumor progression. Investigation of the mechanism of action of BTApep-TAT demonstrated that BORIS underwent ADP ribosylation upon double- or single-strand DNA damage. Substitution of five conserved glutamic acid (E) residues with alanine residues (A) between amino acids (AAs) 198 and 228 of BORIS reduced its ADP ribosylation. Inhibition of ADP ribosylation of BORIS by a site-specific mutation or by BTApep-TAT treatment blocked its interaction with Ku70 and impaired the function of BORIS in DNA damage repair. The present study identified an inhibitor of BORIS, highlighted the importance of ADP ribosylation of BORIS, and revealed a novel function of BORIS in DNA damage repair. The present work provides a practical method for the future screening or optimization of drugs targeting BORIS.

中文翻译：

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BTApep-TAT 肽抑制 BORIS 的 ADP 核糖基化以诱导癌症中的 DNA 损伤

印迹位点调节器的兄弟 (BORIS) 在大多数癌症中都有表达，并且通常与患者的生存期短和预后不良有关。BORIS抑制细胞凋亡并促进癌细胞增殖。然而，其作用机制尚未阐明，也没有已知的 BORIS 抑制剂。噬菌体展示文库用于寻找 BORIS 抑制肽，并鉴定了 BTApep-TAT。将 BTApep-TAT 处理的 H1299 细胞的 RNA 测序图谱与 BORIS 敲低细胞的 RNA 测序图谱进行了比较。BTApep-TAT 的抗肿瘤活性在非小细胞肺癌 (NSCLC) 异种移植小鼠模型中进行了评估。BTApep-TAT 还用于研究 BORIS 的翻译后修饰 (PTM) 以及 BORIS 在 DNA 损伤修复中的作用。构建了 BORIS 的定点突变体并将其用于研究 PTM 和 BORIS 的功能。BTApep-TAT 在癌细胞中诱导 DNA 损伤并抑制 NSCLC 异种移植肿瘤的进展。对 BTApep-TAT 作用机制的研究表明，BORIS 在双链或单链 DNA 损伤时发生 ADP 核糖基化。在 BORIS 的第 198 位和第 228 位氨基酸 (AAs) 之间用丙氨酸残基 (A) 取代五个保守的谷氨酸 (E) 残基降低了其 ADP 核糖基化。通过位点特异性突变或通过 BTApep-TAT 处理抑制 BORIS 的 ADP 核糖基化阻断了其与 Ku70 的相互作用并损害了 BORIS 在 DNA 损伤修复中的功能。本研究确定了一种 BORIS 抑制剂，强调了 ADP 核糖基化 BORIS 的重要性，并揭示了 BORIS 在 DNA 损伤修复中的新功能。目前的工作为未来筛选或优化靶向 BORIS 的药物提供了一种实用的方法。