8β-glycyrrhetinic acid as major bioactive component of Glycyrrhiza glabra downregulates expression of CD44 and epithelial-mesenchymal transition markers and inhibits xenograft tumor growth in gastric cancer stem cells

Background: Gastric cancer (GC) is a common malignancy with high rates of recurrence, metastasis, and drug resistance, often attributed to gastric cancer stem cells (CSCs). CD44, a surface marker upregulated in CSCs, plays a critical role in promoting epithelial-mesenchymal transition (EMT). 18β-glycyrrhetinic acid (GA), a major bioactive compound of Glycyrrhiza glabra, has known anti-inflammatory and anticancer properties. This study aimed to investigate the effects of GA on CD44 expression, EMT markers, and tumor growth in gastric CSCs. Methods and Results: Gastric CSCs were cultured in serum-free medium with EGF and B-27 under nonadherent conditions and treated with varying GA concentrations (20–160 µM) for 24, 48, and 72 hours. Cell viability was assessed using the MTT assay. mRNA expression levels of CD44, Bcl-2, and EMT markers (ZEB-1 and Snail-1) were measured by real-time PCR, while CD44 protein expression was analyzed by flow cytometry. GA’s effect on tumor growth was evaluated in a xenograft mouse model. Statistical analyses included one-way ANOVA and paired t-tests, with p ≤ 0.05 considered significant. GA reduced gastric CSC viability in a time- and dose-dependent manner. Treatment with 60 µM GA significantly downregulated the mRNA expression of CD44, Bcl-2, ZEB-1, and Snail-1, and reduced surface CD44 protein expression at 48 and 72 hours. In vivo, GA treatment inhibited tumor growth and significantly reduced tumor volume in mice. Conclusions: GA inhibits gastric CSC proliferation and tumor growth, potentially by suppressing EMT-related pathways via downregulation of CD44. These findings support further investigation of GA as a candidate for CSC-targeted gastric cancer therapies.