Abstract 3078: Targeting the non-canonical neddylation of TGRBR2 suppresses the metastatic potentials of oral squamous cell carcinoma

Abstract Background: Oral squamous cell carcinoma (OSCC) is the most common malignant tumor in the head and neck region and is characterized by rapid growth, strong invasiveness, early cervical lymph node metastasis, and a high overall metastatic rate. Primary surgery followed by adjuvant concurrent chemoradiotherapy is currently the preferred treatment strategy for most patients with advanced OSCC. Cetuximab, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), in combination with radiotherapy, has recently been approved by the U.S. Food and Drug Administration (FDA) for the treatment of recurrent or metastatic OSCC. However, TKI resistance mediated by alternative activation of the transforming growth factor-β (TGF-β) signaling axis has been reported in non-small cell lung cancer. Therefore, elucidating the crosstalk between TGF-β receptor signaling and EGFR-mediated signal transduction may be critical for the future precision management of OSCC. Methods: Gene set enrichment analysis (GSEA) was applied to predict the potential mechanisms through which the protein neddylation inhibitor MLN4924 (Pevonedistat) suppresses cellular migration and lymph node metastasis in OSCC. Site-directed mutagenesis was performed to confirm the requirement of TGFBR2 neddylation in promoting OSCC metastatic potential. A pulldown assay was used to validate TGFBR2 neddylation, and a cycloheximide chase assay was employed to evaluate TGFBR2 protein degradation upon MLN4924 treatment in HSC3 cells. Results: We found that MLN4924 treatment effectively suppresses the metastatic potential of OSCC cells both in vitro and in vivo. Site-directed mutagenesis targeting residues K1667 and K1700 (Lys→Arg) confirmed that TGFBR2 neddylation is essential for OSCC metastatic progression. GSEA predicted that MLN4924 mainly suppresses the TGF-β signaling axis in treated cells. Pulldown assays further demonstrated that MLN4924 markedly reduces neddylated TGFBR2 levels in HSC3 cells. Consistently, MLN4924 treatment accelerated TGFBR2 degradation, as shown by cycloheximide chase analysis. In rescue experiments, re-expression of wild-type TGFBR2—but not the K1667R/K1700R neddylation-defective mutant—significantly restored migration in TGFBR2-silenced HSC3 cells. Moreover, knockdown of the E3 ligase c-Cbl substantially decreased TGFBR2 neddylation and impaired cell migration. Conclusion: This study is the first to demonstrate that non-canonical c-Cbl-mediated neddylation of TGFBR2 plays a decisive role in driving OSCC metastatic progression. Citation Format: Yuan-Feng Lin. Targeting the non-canonical neddylation of TGRBR2 suppresses the metastatic potentials of oral squamous cell carcinoma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 3078.