Tacrolimus Enhances the Invasion Potential of Hepatocellular Carcinoma Cells and Promotes Lymphatic Metastasis in a Rat Model of Hepatocellular Carcinoma: Involvement of Vascular Endothelial Growth Factor-C

Purpose. The purpose of this study was to elucidate the effect of tacrolimus treatment on tumor growth and metastasis of hepatocellular carcinoma (HCC). Methods. The effect of tacrolimus was investigated on tumor growth and lymph node metastasis in a rat model of HCC. Angiogenesis and lymphangiogenesis were assessed by CD31 and vascular endothelial growth factor receptor 3 (VEGFR-3) immunostaining. Cell proliferation and invasion were monitored in vitro using the Cell Counting Kit-8 (CCK8) and Matrigel Invasion Chambers, respectively. Levels of vascular endothelial growth factor-C (VEGF-C) expression were measured using quantitative real-time polymerase chain reaction (qRT-PCR), immunohistochemisty and Western blots. Results. Tacrolimus had no effect on the proliferation of HCC in vitro or in vivo. Treatment with tacrolimus resulted in a dose-dependent increase in the invasive potential of HCC cells in vitro, in the density of peritumoral lymphatic vessels, and in the number and volume of metastatic lymph nodes in August Copenhagen Irish (ACT) rats. qRT-PCR, immunohistochemisty, and Western blot revealed that tacrolimus increased the levels of expression of VEGF-C in HCC. Conclusions. Tacrolimus enhanced the invasive potential of HCC cells, facilitating HCC lymphangiogenesis and promoting lymphatic metastasis in a rat model of HCC. This influence may be the result of an increase in VEGF-C expression by HCC cells. Targeting the VEGF-C/Fms-related tyrosine kinase 4 axis may be a novel treatment for HCC patients after liver transplantation.