Hypoxia-inducible factor-1α mediates and regulates angiogenesis-related factors expression in hepatocellular carcinoma

Abstract

Objective: To investigate the expression of hypoxia-inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2) during the progression of liver diseases and the molecular mechanism of HIF-1α in regulating the expression of angiogenic factors in hepatocellular carcinoma (HCC). Methods: Serum samples from hospitalized patients with liver cancer, liver cirrhosis, and chronic hepatitis were collected, and healthy people were used as controls. Mouse models of hepatocarcinogenesis were used to detect the dynamic expression of HIF-1α, VEGF and Ang-2. Enzyme-linked immunosorbent assay was used to quantitatively analyze the serum levels of HIF-1α, VEGF and Ang-2 in patients with liver disease and mice. HIF-1α-specific miRNA expression plasmids was constructed to transfect HepG2 human HCC cells. HIF-1α mRNA transcriptional interference effects were analyzed on biological behavior, VEGF and Ang-2 expression, and epithelial mesenchymal transformation (EMT) in human HCC cell line. The sample means of multiple groups were compared by analysis of variance and q test and the sample rate was compared by χ (2) test. Results: In patients with chronic liver disease, the serum expression of HIF-1α, VEGF and Ang-2 in the liver cancer group (145.6 ± 32.6) μg/L, (458.9 ± 125.3) μg/L and (42.9 ± 5.1) μg/L was significantly higher than the liver cirrhosis (P < 0.001) (79.5 ± 28.4) μg/L, (206.8 ± 56.8) μg/L and (26.2 ± 6.1) μg/L and chronic hepatitis group (60.1 ± 18.8) μg/L, (178.1 ± 85.4) μg/L and (21.8 ± 6.9) μg/L. In addition, HIF-1α was positively correlated with VEGF (r = 0.937, P < 0.001), HIF-1α and Ang-2 (r = 0.933, P < 0.001), and VEGF and Ang-2 (r = 0.910, P < 0.001). Mouse models of hepatocarcinogenesis confirmed that HIF-1α, VEGF and Ang-2 had progressively increased during the process of malignant transformation from normal hepatocytes, hepatocyte degeneration, and precancerous lesions to canceration. HIF-1α miRNA intervention plasmid had transformed HepG2 cells. Compared with the blank group, HIF-1α mRNA, HIF-1α, VEGF and Ang-2 were decreased by 88.1%, 59.8%, 54.0% and 36.0% at 72h, respectively. The expression level of EMT-related protein Snail (0.26 ± 0.02 and 0.67 ± 0.09, q = 6.75, P < 0.003), VIM (0.27±0.08 and 0.73±0.04, t = 10.35, P < 0.001) and Twist (0.24 ± 0.07 and 0.73 ± 0.02, q = 12.08, P < 0.001) was significantly reduced, but the expression level of E-cadherin (0.76 ± 0.08 and 0.27 ± 0.09, q = 7.05, P < 0.002) was significantly increased. Conclusion: HIF-1α mediates and regulates angiogenesis-related factors such as VEGF and Ang-2 expression in hepatocellular carcinoma. Furthermore, HIF-1α transcriptional interference can significantly affect the biological characteristics and EMT transformation of hepatocellular carcinoma cells.