Hongqing Xi, Lin Chen 

Department of General Surgery, Chinese People’s Liberation Army General Hospital

Objective:To investigated the expression of Lgr5 in gastric cancer and determine the effect of Lgr5expression on tumor angiogenesis. Method: Lgr5, VEGF exprssion and microvessel density (MVD) were detected by immunohistochemistry in 318 cases of gastric cancer. Western blotting was used to determine the expression of Lgr5 and VEGF in 75 cases of gastric carcinoma and matched normal mucosa. Small interference RNA technique was employed to knockdown Lgr5 mRNA expression. Western blotting and real-time quantitative PCR (qRT-PCR) were performed to detect the expression of Lgr5 and VEGF protein and mRNA in Lgr5 siRNA transfected gastric cancer cell. The effect of silencing Lgr5 on angiogenesis was examined by assessing human umbilicalvein endothelia cell (HUVEC) capillary tube formation. Result: Lgr5 expression was up-regulated in gastric cancer, and was positively correlated with VEGF (r=0.305, P=0.001), and MVD (r=0.312, P=0.001).According to Western blot analysis, a positive correlation was observed between the expression of Lgr5 and VEGF protein (r=0.921, P=0.001). Silencing of Lgr5expression resulted in supression of VEGF mRNA and protein (all P=0.001). Moreover, When HUVECs stimulated with conditioned medium from Lgr5 siRNA-transfected gastric cancer cells, tube formation was significantly decreased(2.51±0.19 mm/mm²) compared to the treatment with regular cell culture medium (DMEM) (7.34±0.30mm/mm²) or medium from control siRNA-transfected cells (7.18± 0.33mm/mm²) (All P=0.001). Conclusion:Lgr5 play important roles in the angiogenesis and Lgr5-specific

siRNA could be designed into an effective therapeutic agent to inhibit the gastric cancer angiogenesis.

Key Words: Gastric cancer  Lgr5  Angiogenesis