A neuropeptide, calcitonin gene-related peptide (CGRP), is widely distributed in neuronal systems and exhibits numerous biological activities. Using CGRP-knockout mice (CGRP-/-), we examined whether or not endogenous CGRP facilitates angiogenesis indispensable to tumor growth. CGRP increased tube formation by endothelial cells in vitro and enhanced sponge-induced angiogenesis in vivo. Tumor growth and tumor-associated angiogenesis in CGRP-/- implanted with Lewis lung carcinoma (LLC) cells were significantly reduced compared with those in wild-type (WT) mice. A CGRP antagonist, CGRP8-37 or denervation of sciatic nerves (L1-5) suppressed LLC growth in the sites of denervation compared with vehicle infusion or sham operation. CGRP precursor mRNA levels in the dorsal root ganglion in LLC-bearing WT were increased compared with those in non-LLC-bearing mice. This increase was abolished by denervation. The expression of VEGF in tumor stroma was down-regulated in CGRP-/-. These results indicate that endogenous CGRP facilitates tumor-associated angiogenesis and tumor growth and suggest that relevant CGRP may be derived from neuronal systems including primary sensory neurons and may become a therapeutic target for cancers.
|Number of pages||6|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Publication status||Published - Sep 9 2008|
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