Knockdown of HOXD13 in Oral Squamous Cell Carcinoma Inhibited its Proliferation, Migration, and Influenced Fatty Acid Metabolism

<b>Background:</b> HOXD13, a member of the homeobox gene family, plays a critical role in developmental processes and has been implicated in various malignancies, including pancreatic cancer and glioma. However, its role in oral squamous cell carcinoma (OSCC) remains poorly understood. This study aimed to elucidate the potential of HOXD13 as a diagnostic biomarker and therapeutic target for OSCC. <b>Methods:</b> We conducted a comprehensive analysis of OSCC samples from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA)-head and neck squamous cell carcinoma (HNSCC) databases. Differentially expressed genes (DEGs) with upregulated expression were identified using Venn diagrams. Functional annotation was performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. A protein-protein interaction (PPI) network was constructed, and 10 key hub genes were identified using the cytoNCA method in Cytoscape. Subsequently, these hub genes were validated using quantitative real-time PCR (qRT-PCR) in tissue samples and cell lines. The impact of HOXD13 knockdown on OSCC cell proliferation and migration was assessed through lentiviral transduction followed by Cell Counting Kit-8 (CCk-8), 5-Ethynyl-2'-deoxyuridine (EdU), wound healing, and Transwell assays. Additionally, proteomic sequencing was performed to explore the effects on lipid metabolism-related pathways. <b>Result:</b> Bioinformatic analysis revealed 121 upregulated DEGs in OSCC. Among these, 10 hub genes (FOXM1, CSF2, FN1, HOXD13, MMP9, SPP1, BIRC5, CXCL11, CXCL9, and FOXA2) were identified using the PPI network and Cytoscape analysis. HOXD13 was notably upregulated in OSCC tissues and cell lines, showing high diagnostic potential with an area under the receiver operating characteristics (ROC) curve (AUC) of 0.9. Immune infiltration analysis indicated significant differences in the tumor microenvironment associated with HOXD13 expression levels. Stable knockdown of HOXD13 in OSCC cell lines resulted in a marked reduction in cell proliferation and migration. Proteomic analysis post-HOXD13 knockdown highlighted alterations in fatty acid degradation pathways and increased expression of related metabolic enzymes. <b>Conclusion:</b> HOXD13 is significantly upregulated in OSCC, and its inhibition reduces OSCC cell proliferation and migration. Additionally, HOXD13 affects fatty acid metabolism in OSCC, suggesting its potential as a therapeutic target and biomarker.