Flor Amy C, Wolfgeher Donald J, Kron Stephen J
University of Chicago, Department of Molecular Genetics and Cell Biology, 929 E. 57th Street, Chicago, IL, 60637, USA.
University of Chicago, Department of Molecular Genetics and Cell Biology, 929 E. 57th Street, Chicago, IL, 60637, USA.
Redox Biol. 2025 Mar;80:103504. doi: 10.1016/j.redox.2025.103504. Epub 2025 Jan 23.
During its catalytic cycle, the homodimeric ATPase topoisomerase II alpha (TOP2A) cleaves double stranded DNA and remains covalently bound to 5' ends via tyrosine phosphodiester bonds. After passing a second, intact duplex through, TOP2A rejoins the break and releases from the DNA. Thereby, TOP2A can relieve strain accumulated during transcription, replication and chromatin remodeling and disentangle sister chromatids for mitosis. Chemotherapy agents such as etoposide are poisons that trap TOP2A mid-cycle, covalently bound to cleaved DNA, leaving behind DNA double strand breaks and activating DNA damage response. While etoposide has been proposed to stabilize the TOP2A-DNA cleavage complex (TOP2Acc) via interfacial inhibition, we have elucidated a complementary mechanism mediated by the ability of etoposide and other TOP2A poisons to induce oxidative stress. Consequently, lipid peroxidation and accumulation of lipid-derived electrophiles such as 4-hydroxynonenal (HNE) results in covalent modification of TOP2A, both blocking ATPase activity and trapping TOP2Acc. HNE modifies multiple sites on human TOP2A in vitro, including alkylating Cys216 in the ATPase domain in a DNA-dependent fashion. Taken together, our data suggest an underappreciated role for TOP2A as a redox sensor in tumor cells, connecting oxidative stress to DNA damage signaling and thereby creating a target for redox-active drugs.
在其催化循环中，同二聚体ATP酶拓扑异构酶IIα（TOP2A）切割双链DNA，并通过酪氨酸磷酸二酯键与5'端保持共价结合。在使第二条完整的双链DNA通过后，TOP2A重新连接断裂处并从DNA上释放。由此，TOP2A可以缓解转录、复制和染色质重塑过程中积累的张力，并解开有丝分裂中的姐妹染色单体。像依托泊苷这样的化疗药物是毒物，它们会在TOP2A的循环中期捕获其与切割后的DNA共价结合，留下DNA双链断裂并激活DNA损伤反应。虽然有人提出依托泊苷通过界面抑制作用来稳定TOP2A-DNA切割复合物（TOP2Acc），但我们已经阐明了一种由依托泊苷和其他TOP2A毒物诱导氧化应激的能力所介导的互补机制。因此，脂质过氧化以及脂质衍生的亲电试剂如4-羟基壬烯醛（HNE）的积累导致TOP2A的共价修饰，既阻断了ATP酶活性又捕获了TOP2Acc。HNE在体外修饰人TOP2A的多个位点，包括以DNA依赖的方式烷基化ATP酶结构域中的半胱氨酸216。综上所述，我们的数据表明TOP2A在肿瘤细胞中作为氧化还原传感器的作用未被充分认识，它将氧化应激与DNA损伤信号联系起来，从而为氧化还原活性药物创造了一个靶点。
