Yuanhuacine suppresses head and neck cancer growth by promoting ASCT2 degradation and inhibiting glutamine uptake.

Head and neck squamous cell carcinoma (HNSCC) cells exhibit a high dependency on glutamine metabolism, making it an attractive target. Despite the well-established link between glutamine reliance and tumor progression, the specific role of glutamine transporters in HNSCC remains poorly understood. The alanine-serine-cysteine transporter 2 (ASCT2), a key glutamine transporter, is overexpressed in HNSCC, and its silencing has been shown to reduce intracellular glutamine and glutathione levels, inhibiting tumor growth. These facts suggest that targeting ASCT2-mediated glutamine uptake could offer a promising therapeutic strategy for HNSCC. But no clinically approved drugs directly target ASCT2, and challenges such as the limited stability of antisense oligonucleotides persist. In this study we evaluated the correlation between ASCT2-mediate glutamine metabolism and its impact on HNSCC patients. We established a virtual screening method followed by cytotoxic assays to identify small molecules that specifically target ASCT2. Among the top 15 candidates, we identified yuanhuacine (YC) as the most potent antitumor compound with IC₅₀ values of 1.43, 6.62, and 6.46 μM against HN6, CAL33, and SCC7 cells, respectively. We demonstrated that YC (0.3-5 μM) dose-dependently induced ASCT2 degradation by recruiting the E3 ubiquitin ligase RNF5, inhibiting glutamine uptake in HN6 cells. This disruption led to mitochondrial dysfunction and enhanced the therapeutic efficacy of YC. Our results highlight YC as a promising regulator of ASCT2-mediated glutamine metabolism in HNSCC.