This Article Full Text Full Text (PDF) Supplementary Data All Versions of this Article: 0008-5472.CAN-08-4051v1 69/7/2801    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lahdenranta, J. Articles by Fukumura, D. Search for Related Content PubMed PubMed Citation Articles by Lahdenranta, J. Articles by Fukumura, D.

Endothelial Nitric Oxide Synthase Mediates Lymphangiogenesis and Lymphatic Metastasis

Edwin L. Steele Laboratory, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts

Requests for reprints: Dai Fukumura or Rakesh K. Jain, Edwin L. Steele Laboratory for Tumor Biology, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, 100 Blossom Street - Cox 7, Boston MA 02114. Phone: 617-726-8143; Fax: 617-724-5841; E-mail: dai{at}steele.mgh.harvard.edu or jain{at}steele.mgh.harvard.edu.

Key Words: nitric oxide • lymphangiogenesis • lymphatic metastasis • intravital microscopy • VEGF-C

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. [Cancer Res 2009;69(7):2801–8]