Objective To investigate the effect of supernatant from carcinoembryonic antigen -related cell adhesion molecule 1(CEACAM1)gene RNAi glioma SHG44 cells on human umbilical vein endothelial cell proliferation and angiogenesis in vitro .Methods Three pairs of specific siRNA targeting CEACAM 1 were de-signed and synthesized , and then transiently transfected into SHG 44 cells via cathodolyte liposome transfection method.The supernatant from cultured glioma SHG 44 cells was collected as the conditional medium 48 h after transfection.RT-PCR was used to detect CEACAM1 and VEGF expression at mRNA level after CEACAM1 gene RNAi.The expression of VEGF in supernatant was measured by ELISA .The proliferation of HUVEC was assessed by MTT method after co-cultured with supernatant .The migration of HUVEC was examined by using a Transwell assay.The ability of angiogenesis was measured by capillary -like network formation assay .Results Forty -eight hours after the 3 pairs of specific CEACAM1 siRNA were transfected into SHG44 cells,RT-PCR results showed that the expression of CEACAM 1 mRNA was significantly inhibited compared with those in the normal control and the negative control groups (P<0.01).The most significant interference effect was CEACAM 1-siR-NA3.Expression of VEGF mRNA was remarkably reduced ,and expression of VEGF protein in the supernatant was also reduced after transfection of CEACAM 1-siRNA for 48 h.The proliferation of HUVEC was inhibited , HUVEC migration and tube capillary -like formation were decreased .Conclusion CEACAM1-siRNA can ef-fectively suppress the expression of CEACAM 1 mRNA in human glioma SHG44 cells,may inhibit HUVEC prolif-eration,migration and tube capillary -like formation via down -regulated the secretion of VEGF in vitro .