Abstract: Objective To explore the levels of osteopontin (OPN) in gastric cancer tissues, gastric cancer cell lines and stem cells (SCs), and investigate the relationship between OPN and angiogenesis. MethodsGastric cancer cell lines SGC-7901 and BGC-823CSCs were used to screen out SCs in suspension by serum free medium followed by detection of the surface markers of gastric cancer SCs Lgr5 and CD44. The levels of OPN protein and mRNA in gastric cancer tissues, adherence cells (ACs) and SCs were examined by Western blotting and RT-PCR. The angiogenic activity of OPN was evaluated by the tube formation assay. ResultsCompared with adjacent non-cancerous tissues, OPN was highly expressed in four out of five gastric cancer tissues in the current study. High expression of Lgr5 and CD44 in gastric cancer SCs indicated the successful screening of the targeted cells. Moreover, the levels of OPN protein and mRNA were higher in SCs than those of ACs (P<0.05). The tube formation assay demonstrated that OPN had strong angiogenic activity (P<0.05). ConclusionsGastric cancer SCs can affect the proliferation and invasion of gastric cancer cells by regulating angiogenesis through overexpression of OPN.