Objective: To determine whether polymorphism of NOS2A promoter -969G>C is associated with the portal hypertension of liver cirrhosis.
Methods: A case control study covering 106 patients with liver cirrhosis due to hepatitis B virus(HBV) in comparison with 108 controls was performed using PCR-restriction fragment length polymorphism. The NOS2A mRNA and protein expression in liver cirrhosis tissues were detected by reverse transcription-PCR and Western blot. The recombinant plasmids of NOS2A promoter luciferase reporter gene were constructed and were transfected transiently into HepG2 cells for analyzing the functional activity of the promoter.
Results: The frequencies of the C allele and GC genotype at NOS2A promoter -969G>C were significantly higher in portal hypertension group (16.9%, 33.8%) than in control group(8.8%, 17.6%)(P<0.05), and positive correlation (r=0.18) and association (OR=2.42) were noted. There was no significant difference in frequency distribution between single liver cirrhosis group and control group(P>0.05). The expressions of NOS2A mRNA and protein in liver cirrhosis tissues were more increased in C allele carriers with liver cirrhosis than in G allele carriers with liver cirrhosis, which led to higher functional activity of the promoter. Multivariate logistic regression analysis revealed that NOS2A polymorphism at promoter -969G>C is an independent novel risk factor for the occurrence of portal hypertension in patients with liver cirrhosis.
Conclusion: The polymorphism of NOS2A promoter -969(G>C) is associated with portal hypertension of liver cirrhosis, which results in functional activity increase of NOS2A promoter and is an independent risk factor for portal hypertension.