Abstract 4117: ADAR1-mediated RNA editing of KCTD13s promotes pancreatic cancer metastasis by impeding RhoA ubiquitination

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease with limited therapeutic options and a poor prognosis. Adenosine-to-inosine (A-to-I) RNA editing, a crucial post-transcriptional modification, introduces nucleotide changes in RNA sequences. However, few protein-recoding editing targets with functional significance have been identified. In this study, we propose that the ADAR1-KCTD13s-RhoA/ROCK1 signaling axis plays a critical role in PDAC progression. Methods: We performed an in-depth analysis of A-to-I RNA editing using RNA-sequencing, validated by Sanger sequencing. In vitro phenotypic assays, including proliferation, colony formation, migration, and invasion tests, were conducted. In vivo studies included an orthotopic pancreatic tumor growth model and a lung metastasis model. Protein interactions were evaluated using immunoprecipitation, protein stability was assessed with cycloheximide (CHX) treatment, and ubiquitination was examined with MG132 treatment. Results: Our analysis of A-to-I modifications in PDAC tissues and cell lines identified KCTD13s as a novel protein-recoding RNA editing target. Increased KCTD13s editing levels, driven by the overexpression of adenosine deaminase acting on RNA 1 (ADAR1), were associated with poor survival in PDAC patients. Functional experiments demonstrated that KCTD13s editing promotes pancreatic cancer metastasis. Mechanistically, this amino acid alteration stabilizes the KCTD13s protein by preventing its ubiquitination. The stabilized KCTD13s competes with KCTD13 for binding to CUL3, inhibiting RhoA ubiquitination. This results in elevated RhoA protein levels and activation of the RhoA/ROCK1 signaling pathway. Conclusion: Our findings illuminate the malignancy-promoting role of the ADAR1-KCTD13s-RhoA/ROCK1 signaling axis in PDAC. This study reveals an epigenetic regulatory mechanism mediated by A-to-I RNA editing and highlights the potential of targeting epitranscriptomic pathways for therapeutic intervention in PDAC. Citation Format: Lingxing Zeng, Xiaoyu Wu, Ziming Chen, Jian Zheng. ADAR1-mediated RNA editing of KCTD13s promotes pancreatic cancer metastasis by impeding RhoA ubiquitination [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4117.