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- Title
Role of host angiotensin II type 1 receptor in tumor angiogenesis and growth.
- Authors
Egami, Kimiyasu; Murohara, Toyoaki; Shimada, Toshifumi; Sasaki, Ken-Ichiro; Shintani, Satoshi; Sugaya, Takeshi; Ishii, Masahiro; Akagi, Teiji; Ikeda, Hisao; Matsuishi, Toyojiro; Imaizumi, Tsutomu
- Abstract
Although the renin angiotensin system (RAS) is a major regulator of vascular homeostasis, the role of the RAS in tumor angiogenesis is little understood. Here we show that host angiotensin II (ATII) type 1 (AT1) receptor plays an important role in angiogenesis and growth of tumor cells engrafted in mice. Subcutaneous B16-F1 melanoma-induced angiogenesis as assessed by tissue capillary density and microangiography was prominent in WT mice but was reduced in AT1a receptor-deficient (AT1a-/-) mice. Consequently, tumor growth rate was significantly slower, and the mouse survival rate was greater, in AT1a-/- mice than in WT mice. Tumor growth was also reduced in WT mice treated with TCV-116, a selective blocker of AT1 receptor. Because the beta-galactosidase gene was inserted into the AT1a gene locus in AT1a-/- mice, the site of beta-galactosidase expression represents the AT1a receptor expression in these mutant mice. In tumor-implanted AT1a-/- mice, the major site of the beta-galactosidase expression was macrophages in tissues surrounding tumors. Moreover, the number of infiltrated macrophages was significantly lower in AT1a-/- mice than in WT mice, and double-immunofluorescence staining revealed that these macrophages expressed VEGF protein intensively. Therefore, the host ATII-AT1 receptor pathway supports tumor-associated macrophage infiltration, which results in enhanced tissue VEGF protein levels. The host ATII-AT1 receptor pathway thereby plays important roles in tumor-related angiogenesis and growth in vivo.
- Publication
The Journal of clinical investigation, 2003, Vol 112, Issue 1, p67
- ISSN
0021-9738
- Publication type
Journal Article
- DOI
10.1172/JCI16645