Angiotensin-I-converting enzyme inhibitors may be an alternative anti-angiogenic strategy in the treatment of liver fibrosis and hepatocellular carcinoma. Possible role of vascular endothelial growth factor.

The renin-angiotensin system (RAS) is frequently activated in patients with chronic liver diseases. Angiotensin-II (AT-II), which is produced by angiotensin-converting enzyme (ACE), has many physiological effects, including strong pro-angiogenic activity. AT-II induces the potent angiogenic factor, vascular endothelial growth factor (VEGF). Recent studies have revealed that angiogenesis is an essential process in many pathological events, such as tumor growth including hepatocellular carcinoma (HCC), and even in liver fibrogenesis. ACE inhibitors are currently widely used as anti-hypertensive agents in clinical practice. Studies have found that the ACE inhibitor, perindopril (PE), which is a potent inhibitor of experimental HCC growth and angiogenesis, is associated with the suppression of VEGF at a clinically comparable dose. PE also markedly suppressed the hepatocarcinogenesis step. In liver fibrogenesis, AT-II is known to stimulate proliferation and production of tissue inhibitor of metalloproteinases-1 (TIMP-1) in activated hepatic stellate cells (Ac-HSC), which play a pivotal role in liver fibrosis development. PE markedly inhibited liver fibrogenesis associated with suppression of Ac-HSC proliferation and TIMP-1 expression via protein kinase-C, which serves as an intracellular signaling pathway. Since ACE inhibitor is used widely in clinical practice without serious side effects, it may provide an alternative new strategy for the treatment of liver fibrosis and HCC.