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 further 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, p16ink4a, 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 significantly 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.