Skullcapflavone II Inhibits SLC1A4-Mediated L-Serine Uptake and Promotes Mitochondrial Damage in Gastric Cancer

Abstract

Gastric cancer (GC) is one of the most lethal human malignancies worldwide. Serine metabolism is essential for meeting biosynthetic demands and regulating the redox state of GC cells. This study demonstrates that Skullcapflavone II (SkII) selectively inhibits the proliferation and metastasis of GC cells. Transcriptomic and metabolomic analyses reveal that SkII treatment significantly affects serine metabolism in GC cells, and isotope tracing experiments confirmed that SkII reduces intracellular L-serine levels by inhibiting uptake rather than de novo synthesis. Furthermore, IHC analysis reveal significant upregulation of the L-serine transporter SLC1A4 in GC tissues. Binding studies using PELSA, SPR, DARTS, CETSA, and MD suggest that SLC1A4 is a potential direct target of SkII. SkII-induced disruption of serine metabolism resulted in an imbalance in GSSG/GSH, leading to increased accumulation of intracellular ROS and oxidative stress. This metabolic disruption causes mitochondrial damage, impaired energy production, and increased apoptosis in GC cells. Additionally, in vivo studies reveal that a serine and glycine deficient diet significantly enhanced the antitumor efficacy of SkII, highlighting its potential as a combinatorial therapeutic strategy. These findings provide compelling evidence that SkII is a novel candidate for targeting serine metabolism, suggesting a promising therapeutic approach for treating GC.

Keywords: L‐serine uptake; SLC1A4; gastric cancer; serine metabolism; skullcapflavone II.