Objective: To investigate the expressions of hepatitis B virus x protein (HBx) and hypoxia-inducible factor-1alpha (HIF-1alpha) in hepatocellular carcinoma (HCC) tissues and HepG2 cells under normoxic and hypoxic conditions.
Methods: Immunohistochemistry was used to detect the expressions of HBx and HIF-1alpha in 78 hepatic carcinoma tissues, and their possible relationships were analyzed using SPSS 10.0 statistical software. Immunofluorescence and Western blot were used to investigate the expression of HIF-1alpha in HepG2 and HepG2-X cells under normoxic and hypoxic conditions. Flow cytometric analysis was used to measure reactive oxygen species (ROS) in HepG2 and HepG2-Xd cells under normoxic and hypoxic conditions.
Results: The positive rate of HBx in the hepatocellular carcinoma tissues was 74.36% (58/78), while the positive rate of HIF-1alpha was 69.23% (54/78). Under normoxic condition, HIF-1alpha was mainly localized in the cytoplasm and partially translocated into the nuclei of most HepG2-X cells, while under hypoxic condition the expression of HIF-1alpha was positive in the cytoplasm and nuclei of HepG2 and HepG2-X cells. Under normoxic condition the expression of HIF-1alpha was negative in the HepG2 cells while it was positive in HepG2-X cells, but HIF-1alpha was upregulated time-dependently in both HepG2 and HepG2-X cells under hypoxia condition. Furthermore, HepG2-X cells had a higher level of ROS than HepG2 cells under normoxic condition, while under hypoxic condition, the levels of ROS in HepG2 and HepG2-X cells were not significantly different, but the levels of ROS in HepG2 and HepG2-X cells under hypoxia condition were higher than those under normoxia condition.
Conclusion: HBx and HIF-1alpha were widely expressed in HCC tissues and there is a positive relationship between them. HIF-1alpha can be upregulated by HBx in HepG2 cells under normoxic and hypoxia conditions. Regulation of HIF-1alpha by HBx in HCC might be via the ROS pathway.