Effect of steroids and adenine-arabinoside (araA) on growth and HBsAg production of a human hepatoma cell line

Hepatitis viruses under immunosuppressive agents

Clinical and experimental studies have shown that T cell-mediated immune mechanisms are involved in the pathogenesis of hepatitis B virus (HBV) and hepatitis C virus infection. Immunosuppressants may impair T cell function and thereby reduce immune-mediated hepatocytolysis and virus clearance. In addition, corticosteroid may activate the glucocorticoid responsive element in the HBV genome to enhance HBV replication and gene expression. These combined effects result in an increase of viraemia in association with a decrease of serum aminotransferase and hepatic necroinflammation. In acute infection, use of immunosuppressants will increase the incidence of chronic evolution. In chronic infection, withdrawal of immunosuppressants will be followed by a clinical flare due to a rebound of immune attack to hepatocytes with increased viral load. This may lead to a subsequent decrease of the viraemia. Therefore, short-term use of immunosuppressant before antiviral therapy may be beneficial in the treatment of chronic viral hepatitis. However, the clinical rebound may be extremely severe and lead to hepatitis failure; thus, the patients should be monitored closely upon tapering and after the withdrawal of immunosuppressants. Long-term use of immunosuppressants in patients with hepatitis virus infection is usually deleterious, particularly in patients after organ transplantation. These findings suggest that clinicians should be cautious in the use of immunosuppressants in patients with hepatitis virus infection.

Glucocorticoid stimulates hepatitis B viral gene expression in cultured human hepatoma cells

Glucocorticoids have been shown to influence the severity of hepatitis B virus-related chronic hepatitis in human. However, very little is known about the effects of glucocorticoids on hepatitis B virus replication in vitro. In this report, we used a well-differentiated human hepatoma cell line, Hep3B, transfected with hepatitis B virus complementary DNA as a model to show that a glucocorticoid analog, dexamethasone, can directly stimulate the production of HBsAg and HBeAg. Elevation of 3.5-kb pregenomic RNA and all other viral RNAs in the transfected Hep3B cells after dexamethasone treatment supports the hypothesis that glucocorticoids directly stimulate hepatitis B virus gene expression in vitro. The concentration of dexamethasone for its half-maximal stimulatory activity toward HBsAg, HBeAg and all viral transcripts was approximately 10(-8) mol/L, close to the affinity of glucocorticoid receptors to [3H]-triamcinolone acetonide in Hep3B cells (approximately 10(-8) mol/L). Specific glucocorticoid antagonist RU38486 completely blocked dexamethasone-induced HBV gene expression, suggesting that the stimulatory effect of dexamethasone was mediated through specific glucocorticoid receptors.

Growth-factor independence of a new differentiated hepatitis B virus DNA-negative human hepatoma cell line

The establishment of a new, differentiated, hepatitis B virus DNA-negative, human hepatoma cell line (named PLC/AN/2) is described. Neoplastic liver tissue was obtained during hepatectomy in an HBsAg-negative man. The established cell line is negative for alpha-fetoprotein and carcinoembryonic antigen; it has retained in vitro some of the differentiated functions of normal hepatocytes. Additionally, it presents a distinctive rearrangement (translocation) at the long arm of chromosome 4. The high degree of independence from serum growth factor requirements appears to be a major in vitro characteristic of PLC/AN/2 cells, making them a suitable model system for the more precise definition of the human hepatocellular carcinoma phenotype, including mechanisms of growth control.

Comparative effects of alpha, beta and gamma human interferons on a HBsAg-producing human hepatoma cell line

The effects of all the three types of human interferons (alpha, beta and gamma) on a human hepatoma cell line with hepatitis B virus (HBV)-DNA sequences integrated into the host DNA and producing hepatitis B surface antigen (HBsAg) in culture medium were assayed. The aim of the present research was to test human interferon preparations in an in vitro system for hepatitis B virus, and to compare the observed effects. The results evidenced both the antireplicative activity principally showed by preparations of beta and gamma human interferons and the inhibition of HBsAg production by high concentrations of gamma human interferon.

Characterization of growth parameters of a human hepatoma cell line cultured under serum-free conditions

The PLC/PRF/5 human hepatoma cell line has at least four complete series of hepatitis B virus (HBV)-DNA sequences integrated into the host DNA and produces hepatitis B surface antigen (HBsAg) and several serum proteins in the culture medium. In order to study serum proteins and HBsAg released by these cells under controlled conditions, the serum-free growth of several human hepatoma-derived cell lines was recently investigated. In this paper the growth of PLC/PRF/5 human hepatoma cell line in a serum- and hormone-free medium was investigated. The results represent a tool which might be used in pharmacological research, studies on hormone-binding and virus gene expression.

Insulin reduces HBsAg production by PLC/PRF/5 human hepatoma cell line. Brief report

Although its action at the molecular level is not completely understood, insulin, as well as its antagonist glucagon, certainly plays an important role in the modulation of protein synthesis. In order to observe whether insulin is involved in virus gene expression, we studied its effect on PLC/PRF/5 human hepatoma cell line, which posses HBV DNA sequences integrated at several sites. While human insulin had no effect on cell growth and increased the production of two plasma proteins, a selective inhibitory effect on HBsAg production could be detected. This observation might be useful for further studies both on virus gene expression and insulin action at the molecular level.

Modulation of production of hepatitis B surface antigen by a human hepatoma cell line

Three drugs were assayed for their capacity to inhibit hepatitis B surface antigen (HBsAg) production by the PLC/PRF/5 human hepatoma cell line. The effect on cell growth and HBsAg production of Cordycepin, 6-azauridine, and Hygromicin B is reported. Hygromicin B, a translation inhibitor unable to penetrate normal cells, greatly reduced HBsAg production by growing and confluent cells.

Induced underglycosylation of PLC/PRF/5 human hepatoma cells. Brief report

The production of HBsAg and human plasma proteins by PLC/PRF/5 human hepatoma cell line was studied in the presence of glycosylation inhibitors. The data presented here suggest that HBsAg release in culture medium by these cells is not reduced by an inhibition of glycosylation and that Tunicamycin may play a role in a mobilization of the intracellular pool of antigen.