Endothelial nitric oxide synthase mediates lymphangiogenesis and lymphatic metastasis

Cancer Res. 2009 Apr 1;69(7):2801-8. doi: 10.1158/0008-5472.CAN-08-4051. Epub 2009 Mar 24.

Abstract

Lymphatic metastasis is a critical determinant of cancer prognosis. Recently, several lymphangiogenic molecules such as vascular endothelial growth factor (VEGF)-C and VEGF-D were identified. However, the mechanistic understanding of lymphatic metastasis is still in infancy. Nitric oxide (NO) plays a crucial role in regulating blood vessel growth and function as well as lymphatic vessel function. NO synthase (NOS) expression correlates with lymphatic metastasis. However, causal relationship between NOS and lymphatic metastasis has not been documented. To this end, we first show that both VEGF receptor-2 and VEGF receptor-3 stimulation activate eNOS in lymphatic endothelial cells and that NO donors induce proliferation and/or survival of cultured lymphatic endothelial cells in a dose-dependent manner. We find that an NOS inhibitor, L-NMMA, blocked regeneration of lymphatic vessels. Using intravital microscopy that allows us to visualize the steps of lymphatic metastasis, we show that genetic deletion of eNOS as well as NOS blockade attenuates peritumor lymphatic hyperplasia of VEGF-C-overexpressing T241 fibrosarcomas and decreases the delivery of metastatic tumor cells to the draining lymph nodes. Genetic deletion of eNOS in the host also leads to a decrease in T241 tumor cell dissemination to the lymph nodes and macroscopic lymph node metastasis of B16F10 melanoma. These findings indicate that eNOS mediates VEGF-C-induced lymphangiogenesis and, consequently, plays a critical role in lymphatic metastasis. Our findings explain the correlation between NOS and lymphatic metastasis seen in a number of human tumors and open the door for potential therapies exploiting NO signaling to treat diseases of the lymphatic system.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Growth Processes / physiology
  • Endothelial Cells / enzymology
  • Endothelial Cells / pathology
  • Fibrosarcoma / blood supply*
  • Fibrosarcoma / metabolism
  • Fibrosarcoma / pathology
  • Humans
  • Lymph Nodes / enzymology*
  • Lymph Nodes / pathology
  • Lymphangiogenesis
  • Lymphatic Metastasis
  • Melanoma, Experimental / blood supply*
  • Melanoma, Experimental / metabolism
  • Melanoma, Experimental / pathology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Nude
  • Nitric Oxide / metabolism
  • Nitric Oxide Synthase Type III / antagonists & inhibitors
  • Nitric Oxide Synthase Type III / genetics
  • Nitric Oxide Synthase Type III / metabolism*
  • Phosphatidylinositol 3-Kinases / metabolism
  • Tail / blood supply
  • Vascular Endothelial Growth Factor C / biosynthesis
  • Vascular Endothelial Growth Factor C / metabolism
  • Vascular Endothelial Growth Factor Receptor-2 / metabolism
  • Vascular Endothelial Growth Factor Receptor-3 / metabolism
  • omega-N-Methylarginine / pharmacology

Substances

  • Vascular Endothelial Growth Factor C
  • omega-N-Methylarginine
  • Nitric Oxide
  • Nitric Oxide Synthase Type III
  • Phosphatidylinositol 3-Kinases
  • Vascular Endothelial Growth Factor Receptor-2
  • Vascular Endothelial Growth Factor Receptor-3