Roles for host and tumor angiotensin II type 1 receptor in tumor growth and tumor-associated angiogenesis.
Angiotensin II (AII) is a multifunctional bioactive peptide, and host renin-angiotensin system (RAS) is closely associated with tumor growth. Recent reports have described that AII is a proangiogenic growth factor, and that Angiotensin II type 1 (AT1) receptor antagonists reduce tumor growth and tumor-associated angiogenesis. In this paper, we investigated the participation of AT1 receptor-signaling in cancer progression using murine Lewis lung carcinoma (LLC) cells, which express AT1 receptor, and AT1a receptor gene-deficient (AT1a-/-) mice. When LLC cells were implanted subcutaneously into wild-type (WT) mice, developed tumors showed intensive angiogenesis with an induction of vascular endothelial growth factor (VEGF) a. Compared with WT mice, tumor growth and tumor-associated angiogenesis was reduced in AT1a-/- mice with reduced expression of VEGFa. In AT1a-/- mice, administration of the AT1 receptor antagonist, TCV-116, showed further reductions of tumor growth, tumor-associated angiogenesis, and VEGFa expression. In vitro study, the expression of VEGFa mRNA and the production of VEGFa protein in LLC cells were significantly increased by AII, which were cancelled by AT1 receptor antagonist, CV-11974. Although the expression of other angiogenic factors, such as angiopoietin-1, angiopoietin-2, epidermal growth factor, and VEGF receptor 2 mRNA, was also investigated in tumor tissues, the expression of VEGFa was most correlated with tumor size among those other angiogenic factors. VEGFa induction by AT1 receptor-signaling in both host and tumor tissues is one of key regulators of tumor growth and tumor-associated angiogenesis. In conclusion, tumor tissue RAS as well as host tissue RAS were found to have an important role in tumor growth. AT1 receptor-signaling blockade may be a novel and effective target in the treatment of cancer.
Imai
Nozomi
N
Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine and School of Medicine, Yokohama, Kanagawa, Japan.
Hashimoto
Tatsuo
T
Kihara
Minoru
M
Yoshida
Shin-ichiro
S
Kawana
Ichiro
I
Yazawa
Takuya
T
Kitamura
Hitoshi
H
Umemura
Satoshi
S
D048868:Adaptor Proteins, Signal Transducing / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000494:pharmacology; D015153:Blotting, Western; D018827:Carcinoma, Lewis Lung / Q000378:metabolism / Q000503:physiopathology*; D004797:Enzyme-Linked Immunosorbent Assay; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000503:physiopathology*; D034741:RNA, Small Interfering / Q000235:genetics; D011863:Radioimmunoassay; D012084:Renin-Angiotensin System / Q000187:drug effects / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013777:Tetrazoles / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; C119712:Agtrap protein, mouse; D001562:Benzimidazoles; D001713:Biphenyl Compounds; D034741:RNA, Small Interfering; D013777:Tetrazoles; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; C077793:candesartan cilexetil; C081643:candesartan