Eupatolitin suppresses the invasion and migration of oral squamous cell carcinoma cells by regulating p38 mitogen-activated protein kinase signaling and downregulating cathepsin S/B expression

This study investigated the antimetastatic potential of eupatolitin, a naturally occurring flavonoid, against oral squamous cell carcinoma. MTT assays suggested that eupatolitin exerted no cytotoxic effects. However, Transwell and wound healing assays revealed that eupatolitin suppressed the migration and invasion of oral cancer cells in a dose- and time-dependent manner. Mechanistic investigations indicated that eupatolitin modulated mitogen-activated protein kinase signaling in SCC-9 and SAS cells by activating p38 phosphorylation. In addition, eupatolitin upregulated E-cadherin and downregulated mesenchymal markers such as Slug, Snail, and N-cadherin. Pretreatment with SB203580, a mitogen-activated protein kinase inhibitor, partially reversed the inhibitory effects of eupatolitin on the migration and invasion of both SCC-9 and SAS cells. Furthermore, overexpression of the proteases cathepsin S and cathepsin B blocked the inhibitory effects of eupatolitin. Molecular docking experiments revealed that eupatolitin stably bound to the active sites of cathepsin S and cathepsin B. This study suggests that eupatolitin suppresses, at least partially, the migration and invasion of oral cancer cells by promoting p38 phosphorylation and downregulating cathepsin S and cathepsin B expression. The findings provide experimental evidence supporting the antimetastatic potential of eupatolitin. Nonetheless, further studies are required to confirm its translational relevance. • Eupatolitin suppresses oral cancer cell migration and invasion non-cytotoxically. • Eupatolitin activates p38 MAPK; inhibition by SB203580 reverses its effects. • Eupatolitin blocks EMT by increasing E-cadherin and reducing N-cadherin, Slug, Snail. • Eupatolitin downregulates Cathepsin S/B; their overexpression rescues invasion. • Docking shows eupatolitin stably binds Cathepsin S/B with favorable interaction energy.