pylori disease. Second, AT1R induces vascular endothelial growth factor (VEGF), VEGF-2 receptor and angiopoietin-II by combined paracrine-autocrine mechanisms that transactivate the epidermal growth factor (EGF) receptor, resulting in angiogenesis in cancer tissues.36 Tumor cell expression of VEGF, a major angiogenic factor, induces neovascularization, which enables cancers to metastasize. VEGF mRNA levels and angiogenesis mediated by head AG-14699 and neck squamous cell carcinoma cells are reduced in a dose-dependent manner by administering ACE-I.37 In pancreatic cancer, by combination treatment with losartan and gemcitabine, neovascularization and the expression

of VEGF in the tumor are both markedly suppressed in a magnitude similar to the inhibitory effects against the tumor growth.38 Many studies have demonstrated that the clinically used ACE-I and ARB significantly attenuated the liver fibrosis development in experimental studies learn more and clinical practice and ACE-I significantly attenuated hepatocellular carcinoma growth and hepatocarcinogenesis

along with suppression of neovascularization by inhibition of VEGF expression.39 These observations suggest that RAS signaling involves VEGF-related angiogenesis. Third, AT1R stimulation induces prostate and breast tumor cell proliferation mediated by growth factor-triggered (e.g. EGF) signal transduction pathways.40 However, although the progression of gastric cancer is also related with EGF expression, there is no direct evidence that RAS stimulation induces gastric tumor cell proliferation by interaction with EGF. Important insights into RAS’s role in oncogenesis have come from studies that have taken advantage of experimental mouse tumor models. A role for AT1R in tumor growth, angiogenesis, and metastasis

is supported by studies in which cells were exposed to candesartan, a polycyclic ATIIR antagonist used to treat hypertension. This drug strongly reduces sarcoma size and vascularization and reduces the number of lung cancer metastases as effectively as lisinopril.41 Significant reductions in tumor growth and vascularization have also been observed in response to candesartan in syngeneic mouse melanomas (B16-F1) and in xenograft models of human MCE prostate and ovarian (SKOV-3) cancer cells.42 Orally administered candesartan strongly inhibits lung metastases induced in mice by injected renal carcinoma cells, and reduces VEGF levels and the number of neovessels in the lung nodules.43 Losartan, another AT1R antagonist, also inhibits the production of several growth factors, including VEGF, and reduces rat C6 glioma cell growth in vitro and in vivo.44 These results suggest that AT1R blockade might serve as an effective anticancer strategy. The observation that AT1R is expressed in tumor endothelial cells (in addition to cancer cells themselves)41,43 suggests that AT1R signaling influences tumor neovascularization.