New Model of In-situ Xenograft Lymphangiogenesis by a Human Colonic Adenocarcinoma Cell Line in Nude Mice

Objective: To explore a new model of in-situ xenograft lymphangiogenesis of human colonic adenocarcinomasin nude mice.
Method: On the basis of establishing subcutaneous xenograft lymphangiogenesis model of humancolonic adenocarcinoms, in-situ xenografts were established through the in situ growth of the HT-29 humancolonic adenocarcinoma cell line in nude mice. The numbers of lymphangiogenic microvessels, the expressionof lymphatic endothelial cell markers lymphatic vessel endothelial hyaloronic acid receptor-1 (LYVE-1), D2-40and the lymphatic endothelial growth factors vascular endothelial growth factor-C (VEGF-C), -D (VEGF-D) andreceptor-3 (VEGFR-3) were compared by immunohistochemical staining, Western bolt and quantitative RT-PCRin xenograft in-situ models.
Results: Some microlymphatics with thin walls, large and irregular or collapsedcavities and increased LMVD, with strong positive of LYVE-1, D2-40 in immunohistochemistry, were observed,identical with the morphological characteristics of lymphatic vessels and capillaries. Expression of LYVE-1 andD2-40 proteins and mRNAs were significantly higher in xenografts in-situ than in the negative control group (bothP<0.01). Moreover, the expression of VEGF-C, VEGF-D and VEGFR-3 proteins and mRNAs were significantlyhigher in xenografts in-situ (both P<0.01), in conformity with the signal regulation of the VEGF-C,-D/VEGFR-3axis of tumor lymphangiogenesis.
Conclusions: In-situ xenografts of a human colonic adenocarcinoma cell linedemonstrate tumor lymphangiogenesis. This novel in-situ animal model should be useful for further studyingmechanisms of lymph node metastasis, drug intervention and anti-metastasis therapy in colorectal cancer.