The significance of lymphatic space invasion and its association with vascular endothelial growth factor-C expression in ovarian cancer

The aim of this study is to investigate the significance of lymphatic space invasion (LSI) and tumor VEGF-C expression in the lymphatic spread of ovarian cancer. By performing immunostaining using human ovarian cancer specimens, we first investigated the association between the extent of LSI and tumor VEGF-C expression, tumor lymphangiogenesis, or the lymphatic metastasis. Moreover, by performing in vitro and in vivo experiments, we elucidated the role of VEGF-C in tumor lymphangiogenesis and lymph node metastasis as well as its role as a therapeutic target in ovarian cancer. The presence of LSI was associated with lymph node metastasis in patients with ovarian cancer. VEGF-C overexpression was significantly associated with the increased LSI and LVD in ovarian cancer. VEGF-C stimulated the lymphangiogenesis in vitro, induced the new lymph vessel formation, and increased the lymph node metastasis in mice models of ovarian cancer. The attenuation of VEGF-C expression by the treatment with mTORC1 inhibitor significantly inhibited lymphangiogenesis, and decreased lymph node metastasis in mice models of ovarian cancer. The presence of LSI is an indicator of nodal metastasis and is associated with higher tumor VEGF-C expression and worse clinical outcome of ovarian cancer patients. VEGF-C plays a crucial role in tumor lymphangiogenesis and lymph node metastasis of ovarian cancer.