Neddylation inhibitor MLN4924 sensitizes head and neck squamous carcinoma cells to (S)-10-hydroxycamptothecin.

Head and neck squamous carcinoma (HNSCC) is the seventh most common cancer worldwide. Targeted therapeutic drugs for HNSCC are still being explored. Among them, (S)-10-hydroxycamptothecin (10-HCPT), a specific inhibitor of TOP1, functions by DNA double-strand breaks that can inhibit DNA replication and trigger apoptotic cell death subsequently. Previous studies have reported that MLN4924 exerts potent anti-tumor effects by inhibiting cullin-RING ligases and causing substrate accumulation in a variety of cancers. Here, we show that MLN4924 effectively causes dose-dependent accumulation of topoisomerase I (TOP1) and blocks TOP1 ubiquitination. Importantly, neddylation inhibition with MLN4924 acts synergistically with 10-HCPT to suppress cell growth, migration and apoptosis in HNSCC cells. Mechanistically, transcriptome sequencing shows that the cytotoxic effects of the combination of MLN4924 and 10-HCPT may involve activation of the NFKB1 pathway. Taken together, our results suggest that combined treatment with MLN4924 and 10-HCPT may be an effective strategy in HNSCC.