Topoisomerases play a pivotal role in ensuring DNA metabolisms during replication, transcription and chromosomal segregation. To manage DNA topology, topoisomerases generate break(s) in the DNA backbone by forming transient enzyme-DNA cleavage complexes (TOPcc) with phosphotyrosyl linkages between DNA ends and topoisomerase catalytic tyrosyl residues. Topoisomerases have been identified as the cellular targets of a variety of anti-cancer drugs (e.g. topotecan, irinotecan, etoposide and doxorubicin, and antibiotics (e.g. ciprofloxacin and levofloxacin). These drugs, as well as other exogenous and endogenous agents, convert the transient TOPcc into persistent TOPcc, which we refer to as topoisomerase DNA-protein crosslinks (TOP-DPC) that challenge genome integrity and lead to cell death if left unrepaired. Proteolysis of the bulky protein component of TOP-DPC (debulking) is a poorly understood repair process employed across eukaryotes. TOP-DPC proteolysis can be achieved either by the ubiquitin-proteasome pathway (UPP) or by non-proteasomal proteases, which are typified by the metalloprotease SPRTN/WSS1. Debulking of TOP-DPC exposes the phosphotyrosyl bonds, hence enables tyrosyl-DNA phosphodiesterases (TDP1 and TDP2) to access and cleave the bonds. In this review, we focus on current knowledge of the protease pathways for debulking TOP-DPC and highlighting recent advances in understanding the mechanisms regulating the proteolytic repair pathways. We also discuss the avenues that are being exploited to target the proteolytic repair pathways for improving the clinical outcome of topoisomerase inhibitors.

拓扑异构酶在确保复制、转录和染色体分离过程中的 DNA 代谢方面发挥着关键作用。为了管理 DNA 拓扑结构，拓扑异构酶通过在 DNA 末端和拓扑异构酶催化酪氨酰残基之间形成具有磷酸酪氨酰连接的瞬时酶-DNA 裂解复合物 (TOPcc) 在 DNA 主链中产生断裂。拓扑异构酶已被确定为多种抗癌药物（例如拓扑替康、伊立替康、依托泊苷和多柔比星）和抗生素（例如. 环丙沙星和左氧氟沙星）。这些药物以及其他外源性和内源性药物将瞬时 TOPcc 转化为持久性 TOPcc，我们将其称为拓扑异构酶 DNA-蛋白质交联 (TOP-DPC)，它们会挑战基因组完整性并在不修复时导致细胞死亡。TOP-DPC 的大块蛋白质成分的蛋白水解（减瘤）是一个在真核生物中使用的鲜为人知的修复过程。TOP-DPC 蛋白水解可以通过泛素-蛋白酶体途径 (UPP) 或通过以金属蛋白酶 SPRTN/WSS1 为代表的非蛋白酶体蛋白酶来实现。TOP-DPC 的减量暴露了磷酸酪氨酰键，因此使酪氨酰-DNA 磷酸二酯酶（TDP1 和 TDP2）能够接近并切割这些键。在本次审查中，我们专注于当前关于减少 TOP-DPC 的蛋白酶途径的知识，并强调在理解调节蛋白水解修复途径的机制方面的最新进展。我们还讨论了用于靶向蛋白水解修复途径以改善拓扑异构酶抑制剂临床结果的途径。