Raw image Data for Inherent electrochemical activity of extrachromosomal DNA hub buffers spatial redox stress in nucleus

Extrachromosomal DNA (ecDNA) is a key factor driving the malignant progression of tumors. Given that ecDNA lacks canonical high-order chromatin compaction, the mechanism by which ecDNA effectively maintains its structural integrity and functional stability in the redox active environment of tumor cells remains unclear. Using metabolomics, biochemistry and imaging assays in human cancer cells and mouse models, we herein show that ecDNA hub establishes an active electrochemical environment, mediating inherent electrochemical activity, which drives the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH) through a non-enzymatic mechanism. GSH forms a protective "cloud" around ecDNA hubs, shielding ecDNA from damage and sustaining oncogene expression. Lastly, using spermidine, which disrupts the interfacial environment of ecDNA hubs, we found that disrupting the redox balance of ecDNA hubs drives tumor death. This study demonstrates a non-enzymatic function of ecDNA hubs that establishes a self-reinforcing maintenance loop, revealing a novel paradigm for cancer biology.