Abstract: Objective To explore a new model of in-situ xenograft lymphangiogennesis of human colonic adenocarcinomas in nude mice.Method On the basis of establishing subcutaneous xenograft lymphangiogenesis model of human colonic adenocarcinoms,in-situ xenograft lymphangiogenic models of human colonic adenocarcinomas were established through the in situ growth of human colonic adenocarcinoma cell line HT-29 in nude mice.The number of lymphangiogenetic microvessels,the expression of lymphatic endothelial cell markers lymphatic vessel endothelial hyaloronic acid receptor-1 (LYVE-1),D2-40 and lymphatic endothelial growth factors vascular endothelial growth factor-C (VEGF-C),-D (VEGF-D) and receptor-3 (VEGFR-3) were compared by immunohistochemical staining,Western bolt and quantitative RT-PCR in xenograft in-situ models.Results Some microlymphatics with thin walls,large and irregular or collapsed cavities and increased LMVD,with strong positive of LYVE-1,D2-40 in immunohistochemistry,were observed,and identical with the morphological characteristic of the lymphatic vessels and capillaries.And,the expression of LYVE-1 and D2-40 proteins and mRNAs were significantly higher in xenografts in-situ than those of the negative control group (both P<0.01).Moreover,the expression of VEGF-C,VEGF-D and VEGFR-3 proteins and mRNAs were significantly higher in xenografts in-situ (both P<0.01),that was in conformity with the signal regulation of VEGF-C,-D/VEGFR-3 axis of tumor lymphangiogennesis.Conclusions In situ xenografts of human colonic adenocarcinomas there have been tumor lymphangiogenesis.The in-situ model of xenograft lymphangiogenesis may act as an ideal,referential,new animal model for further studying of lymph node metastasis mechanism,drug intervention and anti-metastasis therapy in colorectal cancer.

Key words: Colonic neoplasm, Models,animal, Lymphangiogenesis