Trefoil Factor‐3 Is a Hypoxia‐Triggered Pro‐Tumorigenic Factor in Hepatoblastoma

Background & Aims: Hepatoblastoma (HB) is the most common malignant liver tumour in children. Despite improved survival in low-risk disease, outcomes for advanced or relapsed HB remain poor, emphasising the need for new therapeutic targets. Hypoxia, a hallmark of aggressive tumours, has recently been implicated in HB pathogenesis, but the molecular mechanisms involved are unclear. This study aimed to characterise the hypoxia-driven transcriptomic landscape of HB and identify key mediators of tumour progression. Methods: Transcriptomic analyses of HB cell lines cultured under normoxic and hypoxic conditions were combined with bioinformatic interrogation of public HB datasets, immunohistochemistry of human and murine tumours and plasma ELISA assays. Functional roles of trefoil factor 3 (TFF3) were evaluated through overexpression and shRNA-mediated knockdown in vitro and in a β-catenin/ YAP-driven mouse model of HB. Results: Hypoxia induced broad transcriptional reprogramming in HB cells, including significant upregulation of TFF3, a secreted oncogenic peptide. TFF3 expression was elevated in HB tissues and plasma, and colocalized with hypoxia marker carbonic anhydrase 9 (CA9). TFF3 promoted proliferation, anchorage-independent growth and cisplatin resistance under both normoxia and hypoxia. Knockdown of murine Tff3 suppressed tumour formation and angiogenesis in vivo. Transcriptomic and molecular analyses revealed that TFF3 sustains C-MYC expression and modulates mTOR/GSK3β signalling. Conclusions: TFF3 is a hypoxia-inducible factor that enhances HB cell proliferation, survival and chemoresistance. Its tumour-promoting activity through C-MYC and mTOR pathways identifies TFF3 as a potential therapeutic target and circulating biomarker in hepatoblastoma.