DADS Regulates EMT and Chemotherapy Resistance by Inhibiting RORα/β-Catenin Signaling through PKCα-Dependent Phosphorylation in Gastric Cancer.

OBJECTIVES: Gastric cancer (GC) is often associated with high invasiveness, epithelial-mesenchymal transition (EMT), and resistance to 5-fluorouracil (5-FU), highlighting the need for novel therapeutic targets. This study explored whether diallyl disulfide (DADS) upregulates retinoic acid-related orphan receptor alpha (RORα) to weaken the protein kinase C alpha (PKCα)/RORα-mediated RORα/β-catenin pathway, thereby inhibiting GC cell invasion, epithelial-mesenchymal transition (EMT), and enhancing 5-FU sensitivity. METHODS: Human GC cell lines MGC-803 and SGC7901 were treated with DADS, RORα agonist SR1078/antagonist T0901317, and PKCα agonist TPA/antagonist GO6976. Cell proliferation (MTT), migration (scratch assay), invasion (Transwell), protein expression (Western blot), protein interactions (coimmunoprecipitation), and localization (immunofluorescence) were detected. Apoptosis and 5-FU sensitivity-related proteins were examined. Experiments were triplicated; statistics used t-test/ANOVA (p < 0.05). RESULTS: DADS/SR1078 inhibited GC cell proliferation/migration/invasion, upregulated RORα/E-cadherin, downregulated nuclear β-catenin/TGF-β1/Rac1/Vimentin, and weakened EMT (reversed by T0901317). DADS/TPA upregulated RORα/p-RORα/PKCα/p-PKCα, promoted PKCα-RORα binding, and downregulated RORα/β-catenin target genes (counteracted by GO6976). DADS upregulated caspase-3 and downregulated Bcl-2/P-gp/XIAP via RORα, promoting apoptosis and 5-FU sensitivity. CONCLUSION: DADS inhibits GC progression and enhances 5-FU sensitivity by PKCα/RORα-mediated downregulation of RORα/β-catenin signaling, paralleling SR1078/TPA effects. It may act as a novel RORα agonist for GC therapy.