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Background: Hepatitis B virus (HBV) infection in the body can damage liver cells and cause disorders in blood lipid metabolism. Apolipoprotein C3 (ApoC3) plays an important role in the regulation of lipid metabolism, but no study on the HBV regulation of ApoC3 has been reported. This purpose of this study was to investigate the effect of HBV on ApoC3 expression and its regulatory mechanism. Methods: The expression levels of ApoC3 mRNA and protein in the human hepatoma cell lines HepG2 and HepG2. 2.15 were determined using real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blot. The HepG2 cells were co-transfected with the ApoC3 gene promoter and either HBV-infected clone pHBV1.3 or its individual genes. The changes in luciferase activity were assayed. The expression levels of ApoC3 mRNA and protein were determined using RT-qPCR and Western blot. The content of ApoC3 in the supernatant of the cultured cells was determined using an enzyme-linked immunosorbent assay (ELISA). The sera were collected from 149 patients with HBV infection and 102 healthy subjects at physical examination as the normal controls. The serological levels of ApoC3 in the HBV group and the normal control group were determined using ELISA. The contents of serum triglyceride (TG) and very-low-density lipoprotein (VLDL) in the HBV patients and the normal control were determined using an automatic biochemical analyser. Results: The expression levels of ApoC3 mRNA and protein were lower in the HepG2.2.15 cells than in the HepG2 cells. pHBV1.3 and its X gene could inhibit the activity of the ApoC3 promoter and its mRNA and protein expression. The serum levels of ApoC3, VLDL and TG were 65.39 ± 7.48 μg/ml, 1.24 ± 0.49 mmol/L and 0.46 ± 0. 10 mmol/L in the HBV patients and 41.02 ± 6.88 μg/ml, 0.76 ± 0.21 mmol/L, 0.29 ± 0.05 mmol/L in the normal controls, respectively, statistical analysis revealed significantly lower serum levels of ApoC3, VLDL and TG in HBV patients than in the normal controls (P < 0.05). Conclusion: HBV can inhibit the in vivo and in vitro synthesis and secretion of ApoC3. [ABSTRACT FROM AUTHOR]

Background: Hepatitis B virus (HBV) infection causes acute and chronic liver disease, ultimately leading to the development of liver cirrhosis (LC) and hepatocellular carcinoma (HCC). Phospholipase A2 group IIA (PLA2G2A) plays important roles in the development and progression of many tumors. Thus far, there have been no reports on the association between HBV and PLA2G2A. The present study investigated the effect of HBV infection on PLA2G2A expression and its application in the diagnosis of HBV-related diseases. Methods: Serum levels of PLA2G2A in 308 HBV-infected patients and 185 healthy controls were measured using an enzyme-linked immunosorbent assay (ELISA). The difference in serum levels of PLA2G2A was analyzed among chronic hepatitis B (CHB), LC, and HCC patients. PLA2G2A mRNA and protein expression in HepG2 and HepG2.2.15 cells carrying the integrated HBV genome were measured using reverse transcription polymerase chain reaction (RT-PCR) and western blot assays. The HBV infectious clone pHBV1.3, the control plasmid pBlue-ks and PLA2G2A gene promoter were transfected into HepG2 and HepG2.2.15 cells. After transfection, the luciferase activity was measured in the cells. PLA2G2A mRNA and protein expression levels were examined using RT-PCR and western blot assays. Results: The serum levels of PLA2G2A were 258.3 ± 20.3ng/dl in the healthy controls and 329.0 ± 22.5ng/dl, 385.4 ± 29.3ng/dl and 459.2 ± 38.6ng/dl in the CHB, LC, and HCC patients, respectively. Statistical analyses revealed significantly higher serum levels of PLA2G2A in CHB, LC, and HCC patients than in the healthy controls (P < 0.05), and PLA2G2A levels were elevated in the order of HCC > LC > CHB group. High serum PLA2G2A levels in HCC patients were associated with a lower prevalence of lymph node metastasis and a lower TNM stage. HepG2.2.15 cells carrying the HBV genome expressed higher levels of PLA2G2A mRNA and protein than the HepG2 cells. In addition, HBV triggered PLA2G2A promoter activity and enhanced PLA2G2A mRNA and protein expression compared to the empty vector pBlue-ks. Conclusion: HBV can upregulate the expression of PLA2G2A, and serum levels of PLA2G2A are associated with the progression of HBV-related diseases. [ABSTRACT FROM AUTHOR]