Cystatin SN as a potential marker for gastric cancer and promotes gastric cancer progression

Background: Cystatin SN (cystatin 1, CST1) regulates the progression of many cancers and serves as a diagnostic marker; however, its significance in gastric cancer has not been fully elucidated. Methods: We first analyzed the expression levels of CST1 in gastric cancer dataset in oncomine and UALCAN databases. We next analyzed the relationship between CST1 and prognosis of gastric cancer patients in KM Plotter database and downloaded TCGA GC data to verify this result. We further divided GC patients into two groups according to the level of CST1 expression for GSEA enrichment analysis. Finally, we validated the role of CST1 in gastric cancer by in vitro functional assays. Results: We found that CST1 expression levels in gastric cancer tissues were significantly higher than those in normal control tissues and patients with high CST1 expression had a poorer prognosis. GSEA enrichment analysis showed that the main KEGG signaling pathways enriched in the CST1 high expression group were Coagulation, Epithelial-Mesenchymal-Transition, Complement, Apoptosis, Glycolysis. In vitro functional assay confirmed that inhibition of CST1 significantly inhibited the proliferation, colony-formation,migration and invasion ability of gastric cancer cells. Conclusions: Our study shows that the expression level of CST1 correlates with the development of gastric cancer, and CST1 may be used as a diagnostic marker for poor prognosis of gastric cancer.