FOXN2, identified as a novel biomarker in serum, modulates the transforming growth factor-beta signaling pathway through its interaction with partitioning defective 6 homolog alpha, contributing to the pathogenesis of gastric cancer

Dysregulated expression of Forkhead Box N2 (FOXN2) has been detected in various cancer types. However, the underlying mechanisms by which FOXN2 contributes to the onset and progression of gastric cancer (GC) remain largely unexplored. This study aimed to elucidate the potential role of FOXN2 within GC, its downstream molecular mechanisms, and its feasibility as a novel serum biomarker for GC. Tissue samples from GC patients and corresponding non-cancerous tissues were collected. Peripheral blood samples were obtained from GC patients and healthy controls. The expression of FOXN2 was determined using quantitative real-time PCR, western blotting, and immunohistochemistry. The expression of FOXN2 in GC cells was modulated by transfection with small interfering RNA (siRNA) or the pcDNA 3.1 expression vector. Cell proliferation was assessed using the Cell Counting Kit-8 and 5-ethynyl-2’-deoxyuridine incorporation assays. The migratory and invasive capacities of cells were evaluated by Transwell assays, apoptosis rates were measured by flow cytometry, and the expression of proliferative, apoptotic, and epithelial-mesenchymal transition (EMT) markers were assessed by western blot analysis. FOXN2 was found to be overexpressed in the serum, tissues, and cells of GC, correlating with distant metastasis and TNM staging. FOXN2 demonstrated diagnostic value in differentiating GC patients from healthy individuals, with higher levels of FOXN2 being indicative of poorer survival rates. Silencing FOXN2 in vitro inhibited the proliferation, invasion, migration, and EMT of GC cells, while promoting apoptosis. FOXN2 was shown to regulate the transforming growth factor-beta (TGFβ) receptor signaling pathway in GC cells via its interaction with Partitioning Defective 6 Homolog Alpha (PARD6A). In summary, our data suggest that FOXN2 acts as an oncogenic factor in GC, modulating the TGFβ pathway by binding to PARD6A, thereby influencing gastric carcinogenesis. This study underscores the functional significance of FOXN2 as a potential serum biomarker and therapeutic target in GC.