Objectives: To investigate the relevance of lymphangiogenic gene expression in primary and liver metastasis of colorectal cancer (CRC) and identify determinants of lymphatic invasion.
Background: Lymphatic development promoting vascular endothelial growth factor C (VEGFC) is associated with poor outcome in primary CRC. For colorectal liver metastasis (CRLM), intrahepatic lymph invasion and lymph node metastasis are poor prognostic factors. Exact biological factors promoting lymphatic involvement remain elusive, just as the association with molecular subtypes of CRC.
Methods: We designed a lymphangiogenic gene set (VEGFC, Nrp-2, PDPN, LYVE-1, MRC1, CCL-21) and applied it to large datasets of CRC. Gene expression of the lymphangiogenic signature was assessed in resected CRLM specimens by Rt-QPCR. In vitro experiments were performed with colon cancer cell line Colo320 (high Nrp-2 expression) and human dermal microvascular lymphatic endothelial cells (LECs).
Results: Lymphangiogenic gene expression was associated with poor prognosis in both primary and liver metastasis of CRC. CRLM with high expression of consensus molecular subtype-4 identifier genes also exhibited high lymphangiogenic gene expression. Lymph node recurrence following CRLM resection was associated with high expression of VEGFC and Nrp-2. Blocking Nrp-2 significantly reduced invasion of Colo320 cells through an LEC monolayer.
Conclusions: Lymphangiogenic gene expression is correlated with worse prognosis and consensus molecular subtype-4 in both primary and liver metastatic CRC. VEGFC and Nrp-2 expression may be predictive of lymph node involvement in recurrence after resection of CRLM. Nrp-2, expressed on both tumor and LECs, may have a mechanistic role in lymphatic invasion and is a potential novel target in CRC.