Objective    To study the relationship between Tiam1 gene and lymphangiogenesis in colorectal cancer.     Methods    Tiam1 was silenced by siRNA

then linked with pGenesil-EGFP1

finally transfected into the colorectal cancer cells HCT116. The cells without transfection and transfected with blank vector served as controls. The Tiam1 mRNA expressions were detected by RT-PCR. The expressions of VEGF-C/-D mRNA and protein were detected by RT-PCR and Western blot.     Results    The expressions of Tiam1 and VEGF-C/-D in HCT116 cells with Tiam1 gene silenced were lower than those in control groups.     Conclusion    Tiam1 can affect lymphangiogensis in colon cancer by its effect on VEGF-C/-D. It may be a useful marker for lymphatic metastasis in colorectal cancer.