The relationship between lymphangiogenesis and lymphatic metastasis in murine hepatic carcinoma of high and low metastatic potentialities

Objectives To study the relationship between lymphangiogenesis and lymphatic metastasis in mice bearing hepatic carcinoma and analyze the mechanism of the lymphatic metastasis. Methods Hepatic carcinoma cell lines of high and low potentialities of lymphatic metastasis were injected into the footpads of Balb/c mice. Their metastases to lymph nodes were examined. The tumor tissues of each group were stained with 5'-nucleotidase-ALP to observe the lymphoangiogenesis. The total RNA of high and low metastatic potential cell lines were extracted for metastasis gene DNA array. The vascular endothelial cell growth factor C (VEGF-C) and VEGF-D of each cell line were detected using semi-quantitative RT-PCR and were furthur quantatively analyzed using real time PCR. Results The para-common iliac a. and renal hilar lymph nodes metastases of the high metastatic potential cells were significantly higher than in the controls (P＞0.05). The quantity of lymphatic vessels in the high metastasis group was significantly larger than that of the control group (P＜0.05). The expressions of CD44, E-cadherin, HER2/neu, H-Ras and VEGF-C in the high metastasis group were higher than those in the low metastasis group shown by the cDNA micro array experiment but the expressions of nm23A, nm23-E4, pl6ink4a, CD61 were lower. The VEGF-C expression was higher and the VEGF-D was lower in the high metastasis group compared to those of the low metastasis group shown by semi- quantitative RT-PCR. The secretion of VEGF-D was significantly lower and the ratio of VEGF-C/VEGF-D was signifi- cantly higher in the high metastasis group than the low metastasis group (P＜0.05). Conclusions The lymphatic metastasis of hepatic carcinoma is related to lymphoangiogenesis. The changes of VEGF-C and VEGF-D expressions might be a cause influencing the lymphoangiogenesis. VEGF-C/VEGF-D might be an effective parameter in affecting lymphatic metastases.