Angiotensin II Enhances Proliferation and Inflammation through AT1/PKC/NF-κB Signaling Pathway in Hepatocellular Carcinoma Cells

BACKGROUND/AIMS: The pathogenesis of hepatocellular carcinoma (HCC) is mainly characterized by persistent cycles of liver injury, inflammation, and compensatory hepatocyte proliferation. Angiotensin II (Ang II) behaves as an endogenous pro-inflammatory molecule playing a significant role in HCC, however, the molecular link between Ang II, proliferation and inflammation remains unclear. METHODS: Human HCC cell lines (HepG-2, SMMC-7721, MHCC97-H) were incubated with Ang II at the indicated concentrations for 24, 48, 72 h. MTT, BrdU ELISA, plate colony formation assay, immunohistochemistry, ELISA, small-interfering RNA(siRNA) transfection, quantitative real-time PCR and western blot were applied to assess their functional, morphological and molecular mechanisms in HCC cell lines. RESULTS: High expression of Ang II type 1 receptor (AT1) and low expression of AT2 in HCC cells and tissues were found. Next, Ang II could significantly enhance cell growth and proliferation. Albeit Ang II slightly increased the percentage of HCC cells in the G0/G1 phase using flow cytometry analysis, no statistically significant alterations were shown. Further studies suggested that Ang II could directly induce proliferation associated proteins C-myc and proliferating cell nuclear antigen (PCNA) expressions, and inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and C-reactive protein (CRP) productions in HCC cells. Interestingly, blocking AT1 and AT1 siRNA evidently inhibited Ang II-induced cell proliferation and inflammatory responses in HCC cells. More importantly, these effects may be mediated by AT1/PKC/NF-κB signaling pathway in HCC cell lines. CONCLUSIONS: The results propose that Ang II/AT1/PKC/NF-κB signaling pathway is necessary for proliferation and inflammation of HCC cells, which increases our understanding of the pathogenesis and provides clues for developing new strategies against Ang II-related progress of HCC.