TRIM26 deficiency drives gastric cancer lymph node metastasis via TGF-β signaling activation and modulates gemcitabine response.

[BACKGROUND] Globally, gastric cancer (GC) is a predominant cause of cancer-related death. Lymph node metastasis (LNM) and chemoresistance constitute two major barriers to improving outcomes, as LNM signifies advanced disease and chemoresistance consequently leads to treatment failure. This study systematically investigates the key molecular drivers underlying LNM and chemoresistance in GC to assess their therapeutic relevance.

[METHODS] Our study integrated single-cell and bulk transcriptomic data from GEO and TCGA. The analytical workflow comprised: Firstly, hdWGCNA for co-expression network construction; Secondly, a combination of machine learning algorithms (LASSO, random forest, and SVM-RFE) for core gene screening; Thirdly, pseudotime trajectory analysis (Monocle2/3) to delineate cell state transitions. Cell-cell communication and metabolic pathways were profiled using CellChat and scMetabolism, respectively. Computational pharmacology involved drug sensitivity prediction with the pRRophetic algorithm, complemented by molecular docking and dynamics simulations for structural insights. Finally, TRIM26's functional roles were experimentally validated through CCK-8, Transwell, and colony formation assays, alongside protein-level verification by immunohistochemistry.

[RESULTS] Downregulation of TRIM26 in GC correlated strongly with LNM and poor survival. At single-cell resolution, TRIM26 loss in epithelial cells fueled pro-metastatic crosstalk with endothelial cells and macrophages through SELE-CD44 and SPP1-CD44/integrin axes. This triggered TGF-β activation, TP53 network dysregulation, and metabolic reprogramming of taurine and pantothenate/CoA pathways. TRIM26-low tumors were predicted to be less sensitive to gemcitabine, consistent with higher estimated IC values, a premise bolstered by computational evidence of stable, direct drug binding (free energies: -6.7 and -5.5 kcal/mol) and sustained interactions in 100 ns simulations. Critically, TRIM26 overexpression curtailed tumor growth and invasiveness in the presence of gemcitabine.

[CONCLUSION] TRIM26 inhibits LNM by modulating TGF-β signaling and remodeling the tumor microenvironment. Clinically, low TRIM26 expression identifies tumors with reduced sensitivity to gemcitabine, reflected by higher estimated IC values-a correlation underpinned by computational models demonstrating stable drug binding. Thus, TRIM26 serves as a integrated prognostic and predictive biomarker, positioning it as a promising theranostic target to inform precision therapy strategies in GC.