Abstract Background: Distant metastasis is the major cause of cancer-related mortality in hepatocellular carcinoma (HCC), yet the molecular determinants that confer metastatic competence remain poorly defined. Extrachromosomal circular DNA (eccDNA), a non-chromosomal genetic element capable of amplifying oncogenes and promoting tumor evolution, has recently gained attention. However, the functional landscape of eccDNA-carried genes in HCC and their mechanistic roles in metastatic progression remain undefined. Methods: Paired primary and metastatic HCC tissues were analyzed using Circle-seq to identify metastasis-associated eccDNAs. Candidate drivers were further evaluated through integrated multi-omics analyses and validation using public datasets. Functional studies were performed in HCC cell lines with stable NOSIP overexpression or knockdown, followed by migration and invasion assays. Protein interactors were identified by immunoprecipitation-mass spectrometry. Cellular bioenergetic function was evaluated using Seahorse XF analysis, and the mechanistic relevance of identified interactions was further examined in vitro and in vivo. Results: NOSIP-containing eccDNA was markedly enriched in metastatic HCC samples, and elevated NOSIP expression correlated with poor overall survival. NOSIP overexpression significantly enhanced cell migration and invasion, while knockdown suppressed these phenotypes. Proteomic profiling identified pyruvate dehydrogenase E1 subunit beta (PDHB) as a major NOSIP-binding partner. NOSIP upregulation increased oxygen consumption rate and activated oxidative phosphorylation (OXPHOS), indicating enhanced mitochondrial metabolic activity. These findings demonstrate that eccDNA-mediated NOSIP amplification promotes metastatic traits by engaging PDHB-dependent mitochondrial metabolic reprogramming. Conclusion: In conclusion, this study identifies NOSIP-containing eccDNA as a previously unrecognized molecular driver of OXPHOS-dependent metastatic adaptation in HCC. The proposed eccDNA-NOSIP-PDHB axis reveals a mechanistic link between non-chromosomal genetic amplification and mitochondrial metabolic remodeling, offering a potential metabolic vulnerability for therapeutic intervention in advanced HCC. Citation Format: Xiaorong Lin, Yusheng Luo, Yuxi Pan, Guofei Deng, Yuqing Lin, Yuzhi Zhang, Jiancheng Wang, Shuo Fang. Extrachromosomal circular DNA-mediated NOSIP amplification drives OXPHOS-dependent metastasis in hepatocellular carcinoma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6103.
Lin et al. (2026) studied this question.