Pan-Cancer Landscape of the Novel Oxygen Sensor ADO and Its Potential Role in Hepatocellular Carcinoma

Abstract

Background Hypoxia is a key driver of tumor progression across cancers, yet oxygen-sensing mechanisms beyond HIFs remain underexplored. 2-Aminoethanethiol dioxygenase (ADO) has recently been identified as an oxygen sensor, but its role in malignancy is poorly defined. We conducted a pan-cancer analysis of ADO with a special focus on hepatocellular carcinoma (HCC), to assess its oncogenic significance and clinical potential. Methods A multi-omics pan-cancer analysis of ADO expression and survival was performed using TCGA and GTEx, with validation in HCC across ICGC, GEO, and CNHPP proteomic cohorts. Correlations with genetic, epigenetic, immune, and pathways were evaluated. Drug sensitivity was predicted. Functional validation was conducted in HCC cells through proliferation, colony formation, Western blotting, and xenograft assays. Results ADO was aberrantly expressed across cancers and showed cancer type–specific survival associations. Integrative analyses revealed links with tumor mutation burden, microsatellite instability, chromatin regulator methylation, RNA modification, proliferative signaling (G2M checkpoint, MYC, TGF-β), an immunosuppressive microenvironment, and negative correlations with ROS-responsive genes. In HCC, ADO was consistently overexpressed, associated with advanced stage, poor differentiation, residual disease, and unfavorable survival across independent cohorts. ADO-high HCC showed reduced predicted responsiveness to checkpoint blockade but increased sensitivity to sorafenib and fluorouracil. Experimentally, ADO overexpression activated ERK signaling, upregulated CD276 and HMGB1, and promoted HCC cell proliferation, while ADO depletion suppressed tumor growth in vitro and in vivo, reversible upon re-expression. Conclusion ADO plays oncogenic and immunomodulatory roles in HCC, and may serve as a potential prognostic biomarker and therapeutic target in liver cancer.