83 Quick summary: Pioneering molecular research published in Genes and Diseases has identified the HMGB3 protein as a major driver of aggressive esophageal squamous cell carcinoma, linking its upregulation to rapid tumour proliferation and distant organ metastasis. Laboratory and organoid models reveal that a complex molecular feedback loop integrates inflammatory and developmental signalling pathways to accelerate cancer growth, a process that can be successfully suppressed by targeted enzymatic inhibitors. These oncological findings carry critical significance for healthcare practice and public policy, providing a novel diagnostic biomarker framework and therapeutic blueprint that could guide personalized clinical interventions towards improving survival rates for patients facing high mortality malignancies. Esophageal squamous cell carcinoma (ESCC) remains one of the deadliest cancers worldwide, with high mortality driven by rapid tumour growth and frequent spread to distant sites before diagnosis. Despite treatment advances, outcomes are often poor, underscoring the urgent need to better understand the disease’s molecular drivers. A new study published in Genes & Diseases has identified a key protein, high-mobility group box 3 (HMGB3), as a major contributor to ESCC’s aggressive behaviour. Researchers from the Fourth Military Medical University, 94719 Military Hospital, and Xi’an Medical University in China conducted the work. HMGB3 expression is significantly upregulated in ESCC tissues and cell lines compared with normal counterparts, and higher levels of this non-histone nuclear protein were linked to worse clinical outcomes. In laboratory experiments, increasing HMGB3 boosted cancer cell proliferation, migration, and invasion. Conversely, silencing the protein reduced these malignant phenotypes and decreased the formation of lung metastatic nodules in animal models. The researchers identified a chain of molecular events driving ESCC progression. TGIF2 acts as an upstream transcriptional activator, directly binding to a specific region of the HMGB3 promoter spanning -1138 bp to -894 bp, promoting HMGB3 overexpression. EGFR signalling amplifies this process, as EGF-mediated phosphorylation of TGIF2 further increases HMGB3 protein levels, an effect blocked by the EGFR inhibitor gefitinib. Once overexpressed, HMGB3 interacts with Toll-like receptor 3 (TLR3) at amino acid residues GLU-576, THR-710, and VAL-720, activating downstream NF-κB signalling through increased phosphorylation and nuclear translocation of p65. Activated p65 subsequently binds to the promoters of both TGF-β and TLR3, creating a positive feedback loop that sustains TGF-β production and signalling, driving both tumour growth and spread. Additional analysis using ATAC-seq revealed that HMGB3 also influences the TGF-β pathway by altering chromatin accessibility at sites involving TGF-β receptors and SMAD proteins. The oncogenic activity of the TGIF2–HMGB3 axis ultimately operates through the Smad-dependent TGF-β signalling pathway, integrating TLR3/NF-κB inflammatory signals with TGF-β/Smad developmental pathways. In an independent patient cohort, co-expression of TGIF2, HMGB3, and TGF-β was strongly associated with poor prognosis, with multivariate Cox regression analysis confirming each as an independent risk factor. Patient-derived organoid models further validated the findings, showing that depleting either TGIF2 or HMGB3 markedly suppressed tumour growth. The study represents the first comprehensive characterisation of the TGIF2/HMGB3/TLR3/TGF-β axis in ESCC, a disease that poses a particular challenge in high-incidence regions such as parts of Asia, where current treatments often struggle against advanced disease. The researchers suggest that disrupting the pathway could yield clinical benefits through strategies such as the TGF-β-neutralising antibody 1D11 or NF-κB inhibitors such as BAY 11-7082, to help control tumour proliferation and metastasis. The authors acknowledged limitations, noting the need for greater mechanistic clarity on how HMGB3 precisely regulates TGF-β signalling through combined chromatin remodelling and protein interactions, and that the impact of the TGIF2/HMGB3/TGF-β axis on the broader tumour microenvironment requires further study. They emphasised that larger patient cohorts and expanded single-cell sequencing will be important to confirm clinical utility and support personalised treatments. Further validation and drug development efforts will be essential to translate these findings into improved outcomes for a disease with an urgent need for improved therapeutic options.