Hepatitis B virus mutations associated with in situ expression of hepatitis B core antigen, viral load and prognosis in chronic hepatitis B patients.

In this retrospective study, we investigated the prevalence and significance of mutations in part of the hepatitis B virus (HBV) x gene, and tried to clarify their relationship with clinicopathological or histopathological characteristics and prognosis in patients with chronic hepatitis B (CHB). A total of 83 consecutive CHB patients (1986-1994) were chosen for the present study. Sequence analysis was performed using polymerase chain reaction (PCR) and the direct sequencing method. The histological activity index was described using Scheuer scores. Two-step immunohistochemical staining showed the expression of viral antigens in situ. Tissue HBV DNA levels were determined by fluorescence quantitative real-time PCR. For the prognostic study, all the patients were followed up using clinical and laboratory data. Mutation at nt1726-1730 correlated significantly with decreased expression of HBcAg in situ (P = 0.006) and with lower HBV DNA levels in the liver (P = 0.004). In particular, the CTGAC mutation showed the strongest decrease of the viral load (P = 0.007). By contrast, nt1762/1764 mutation correlated with increased HBcAg (P = 0.005) and higher HBV DNA levels (P = 0.006). The mutants with the wild-type of nt1726-1730 or nt1762/1764 mutation were more prevalent in hepatocellular carcinoma (HCC) patients than in CHB patients. Although the mutations did not correlate with cirrhosis, the frequency of nt1762/1764 mutation in patients with hepatocarcinogenesis was significantly higher than in those without hepatocarcinogenesis (P = 0.011). Mutations at nt1726-1730 and nt1762/1764 are associated with in situ expression of HBcAg and viral load. Higher HBV DNA levels in the liver may be associated with hepatocarcinogenesis. Mutation at nt1762/1764 remarkably increases the risk of hepatocarcinogenesis.

[Chronic hepatitis B virus infection and the methylation status of p16INK4A promoter].

OBJECTIVE: To explore the relationship among HBV-associated histopathological indexes, x gene mutations and the methylation status of p16INK4A promoter in liver with chronic hepatitis B virus infection, in order to illustrate their role in p16INK4A hypermethylation and HCC progression. METHODS: Twenty-three cases of surgically resected HBV-associated hepatocellular carcinoma and twenty-five fine needle aspiration biopsy cases of chronic hepatitis B were chosen for this study. The methylation status of the p16INK4A promoter in tumors, their corresponding peritumoral samples and chronic hepatitis B cases was determined by methylation-specific polymerase chain reaction (MSP). EnVision two-step immunohistochemical staining showed the expression of viral antigens in situ. Tissue HBV DNA levels were determined by real-time fluorescence quantitative PCR. Polymerase chain reaction and the direct sequencing method was used for mutation analysis of HBV x gene. RESULTS: In peritumoral samples (P = 0. 025) and chronic hepatitis B cases (P = 0.029), the expression of HBx protein in methylated groups was all significantly higher than that in unmethylated groups of p16INK4A gene. But in tumors, there was no such significant difference. Other HBV antigens including HBsAg and HBcAg, tissue HBV DNA levels and point mutations of HBV x gene did not show a relationship with the methylation status of p16INK4A gene. CONCLUSION: The data suggest that p16INK4A hypermethylation correlated closely with higher HBx expression in precancerous lesions. HBx may play an important role in the early stage of HBV-associated hepatocarcinogenesis via induction of hepermethylation of p16INK4A promoter.

[Effects of hypoxia and hyperoxia on the regulation of the expression and activity of matrix metalloproteinase-2 in hepatic stellate cell].

OBJECTIVE: To study the effects of hypoxia and hyperoxia on the expression and activity regulation of matrix metalloproteinase-2 (MMP-2) of the hepatic stellate cell (HSC). METHODS: The expression of MMP-2, tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and membrane type matrix metalloproteinase-1 (MT1-MMP) in cultured rat HSC under hypoxic or hyperoxic conditions were detected with immunocytochemistry (LSAB method), the contents of MMP-2, TIMP-2 in culture supernatant with ELISA and the activity of MMP-2 in supernatant with zymography. RESULTS: (1) In the situation of hypoxia for 12 h, the expression of MMP-2 increased (hypoxia group positive indexes: 5.7 +/- 2.0; control: 3.2 +/- 1.0; P < 0.01), while TIMP-2 decreased (hypoxia group positive indexes: 2.5 +/- 0.7; control: 3.6 +/- 1.0; P < 0.05) in HSC, and the activity of MMP-2 in supernatant declined obviously (hypoxia group: 7.334 +/- 1.922; control: 17.277 +/- 7.424; P < 0.01). At the different time courses of hypoxia, the change of expression and activity of MMP-2 was most notable at 6 h. (2) In the situation of hyperoxia for 12 h, the protein contents of MMP-2, TIMP-2 in supernatant were both higher than those of the control, especially the TIMP-2 (hyperoxia group A(450): 0.050 +/- 0.014; control: 0.022 +/- 0.010; P < 0.01), and so was the activity of MMP-2 (hyperoxia group total A: 5.252 +/- 0.771; control: 4.304 +/- 1.083; P < 0.05). The expression of MT1-MMP was also increased. CONCLUSIONS: The HSC is sensitive to the oxygen. Hypoxia accelerates the expression of MMP-2 and the effect is more marked at the early stage. Hyperoxia increases the activity of MMP-2.

Association of p16INK4A hypermethylation with hepatitis B virus X protein expression in the early stage of HBV-associated hepatocarcinogenesis.

The aim of the present study was to explore the relationship between methylation status of the p16(INK4A) promoter and some HBV-related factors, and the role of these factors in p16(INK4A) hypermethylation and hepatocellular carcinoma (HCC) progression. Twenty-three cases of surgically resected HBV-associated HCC and 25 fine-needle aspiration biopsy cases of chronic hepatitis B (CHB) were studied. The methylation status of the p16(INK4A) promoter was determined by methylation-specific polymerase chain reaction (PCR). Two-step immunohistochemical staining showed the expression of viral antigens in situ. Tissue HBV-DNA levels were determined by fluorescence quantitative real-time PCR. PCR and the direct sequencing method were used for mutation analysis. In peritumoral tissues (P = 0.025) and CHB samples (P = 0.029), the expression of hepatitis B virus X protein (HBx) was higher in methylated groups of p16(INK4A) promoter than in unmethylated groups. Other HBV factors including hepatitis B surface antigen and hepatitis B core antigen, tissue HBV-DNA levels and HBV x gene mutations had no relation to the methylation status of p16(INK4A) promoter. The data indicate that p16(INK4A) promoter hypermethylation correlated closely with higher HBx expression in the precancerous lesions, suggesting that HBx may play an important role in the early stage of HBV-associated hepatocarcinogenesis via induction of hypermethylation of p16(INK4A) promoter.