Inhibition of tumour angiogenesis and growth by small hairpin HIF-1 alpha and IL-8 in hepatocellular carcinoma

Abstract

Background & Aims Hypoxia-inducible factor-1 alpha (HIF-1 alpha), a key transcription factor in the cellular response to hypoxia, and interleukin 8 (IL-8), a key mediator of angiogenesis, are important in cancerous tumour growth. In this study, we evaluated the effects of HIF-1 alpha and IL-8 knockdown on angiogenesis and tumour growth in hepatocellular carcinoma (HCC). Methods Hepatocellular carcinoma cell lines were infected with adenoviruses expressing small-hairpin RNA (shRNA) specific for HIF-1 alpha or IL-8, cultured under hypoxic conditions (1% O2), and examined for their levels of HIF-1 alpha, IL-8, and angiogenesis factors using immunoblot. The effects of adenovirus-mediated shRNA-induced HIF-1 alpha and IL-8 knockdown on tumour growth and angiogenesis were also investigated in a subcutaneous Hep3B-tumour mouse model. Results Hypoxia-inducible factor-1 alpha knockdown directly repressed tumour growth, whereas IL-8 knockdown indirectly repressed tumour growth. Combined knockdown of HIF-1 alpha and IL-8 increased survival rates of mice. HIF-1 alpha and IL-8 knockdown also decreased microvessel density and tumour volume in vivo. Similarly, HIF-1 alpha and IL-8 knockdown inhibited the angiogenic effects of HCC cell-conditioned media on tube formation and invasion by endothelial cells in vitro. Conclusion These findings indicate that shRNA-induced HIF-1 alpha and IL-8 knockdown inhibit angiogenesis and tumour growth in HCC. Further development of HIF-1 alpha and IL-8 shRNA technologies could lead to effective therapies for HCC.