Angiogenesis and antiangiogenic therapy in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a hypervascular tumor characterized by neovascularization, which plays an important role in the growth and progression of HCC. Angiogenesis provides a target for novel prognostic and therapeutic approaches to HCC. Assessment of microvessel density using immunohistochemical staining for specific endothelial cell markers such as CD34 has been shown to provide prognostic information independent of conventional pathological parameters in HCC patients. Recent studies have unveiled the important angiogenic factors involved in the regulation of angiogenesis in HCC, although the exact molecular pathways are far from clear. Current data suggest that vascular endothelial growth factor (VEGF) plays a critical role in angiogenesis of HCC. Tumor expression of VEGF has been shown to correlate with tumor invasiveness and prognosis in patients with HCC. VEGF is an important molecular target for antiangiogenic therapy. Studies in animal models have demonstrated the efficacy of antiangiogenic agents such as anti-VEGF antibody and antagonists of VEGF receptors in suppressing hepatocarcinogenesis and growth of HCC. Antiangiogenic therapy has already entered clinical trials in HCC patients and holds the promise of providing an effective novel treatment for HCC, which is of great clinical significance because there is no existing effective systemic therapy for HCC.