C-terminal-truncated hepatitis B virus X protein enhances the development of diethylnitrosamine-induced hepatocellular carcinogenesis.

Hepatitis B virus X protein (HBx) is involved in the development of hepatocellular carcinoma (HCC). The HBx sequence is a preferential site of integration into the human genome, leading to the formation of C-terminal-truncated HBx proteins (Ct-HBx). We previously reported that Ct-HBx proteins were able to potentiate cell transformation in vitro. Our present goal was to compare the ability of Ct-HBx and full-length HBx (FL-HBx) proteins to develop or enhance HCC in transgenic mice. In the absence of treatment, neither Ct-HBx- nor FL-HBx-transgenic mice developed HCC. In young mice treated with diethylnitrosamine (DEN) at 8 months of age, a significantly higher incidence and number of liver lesions were observed in Ct-HBx mice than in FL-HBx and control mice. The earlier development of tumours in Ct-HBx-transgenic mice was associated with increased liver inflammation. At 10 months, macroscopic and microscopic analyses showed that, statistically, FL-HBx mice developed more liver lesions with a larger surface area than control mice. Furthermore, during DEN-induced initiation of HCC, Ct-HBx- and FL-HBx-transgenic mice showed higher expression of IL-6, TNF-α and IL-1ß transcripts, activation of STAT3, ERK and JNK proteins and an increase in cell apoptosis. In conclusion, in DEN-treated transgenic mice, the expression of Ct-HBx protein causes a more rapid onset of HCC than does FL-HBx protein. HBV genome integration leading to the expression of a truncated form of HBx protein may therefore facilitate HCC development in chronically infected patients.

Antiviral activity of Bay 41-4109 on hepatitis B virus in humanized Alb-uPA/SCID mice.

Current treatments for HBV chronic carriers using interferon alpha or nucleoside analogues are not effective in all patients and may induce the emergence of HBV resistant strains. Bay 41-4109, a member of the heteroaryldihydropyrimidine family, inhibits HBV replication by destabilizing capsid assembly. The aim of this study was to determine the antiviral effect of Bay 41-4109 in a mouse model with humanized liver and the spread of active HBV. Antiviral assays of Bay 41-4109 on HepG2.2.15 cells constitutively expressing HBV, displayed an IC(50) of about 202 nM with no cell toxicity. Alb-uPA/SCID mice were transplanted with human hepatocytes and infected with HBV. Ten days post-infection, the mice were treated with Bay 41-4109 for five days. During the 30 days of follow-up, the HBV load was evaluated by quantitative PCR. At the end of treatment, decreased HBV viremia of about 1 log(10) copies/ml was observed. By contrast, increased HBV viremia of about 0.5 log(10) copies/ml was measured in the control group. Five days after the end of treatment, a rebound of HBV viremia occurred in the treated group. Furthermore, 15 days after treatment discontinuation, a similar expression of the viral capsid was evidenced in liver biopsies. Our findings demonstrate that Bay 41-4109 displayed antiviral properties against HBV in humanized Alb-uPA/SCID mice and confirm the usefulness of Alb-uPA/SCID mice for the evaluation of pharmaceutical compounds. The administration of Bay 41-4109 may constitute a new strategy for the treatment of patients in escape from standard antiviral therapy.

Rescue of fertility in homozygous mice for the urokinase plasminogen activator transgene by the transplantation of mouse hepatocytes.

Development of the urokinase plasminogen activator/SCID (uPA/SCID) transgenic mouse model has opened new perspectives for the study of different biological mechanisms such as liver regeneration, stem cell differentiation, and human hepatic pathogens. We observed that homozygous uPA/SCID mice (uPA+/+/SCID) had a small offspring, indicating a fertility defect. The goal of this study was thus to rescue the fertility of homozygous uPA mice. A deregulation of ovarian function with an absence of corpus luteum was observed in female uPA+/+/SCID mice. In male uPA+/+/SCID mice, a decrease of the weight of the testes, epididymis, seminal vesicle, and prostate was measured. This was associated with an absence of seminal and prostatic secretions and a reduction in testicular sperm production. We hypothesized that the infertility of mice was the consequence of uPA-induced liver injury. Thus, in order to rescue liver function, hepatocytes from mice negative for the uPA transgene were transplanted into uPA+/+/SCID mice. Thirty days after cell transplantation, the livers of transplanted uPA+/+/SCID mice were totally repopulated and presented a normal morphology. Furthermore, transplantation restored normal body weight, life span, and reproductive organ function. In conclusion, we demonstrated that the transplantation of uPA+/+/SCID mice with healthy hepatocytes was sufficient to rescue the reproductive capacity of female and male uPA homozygous animals, highlighting the importance of normal liver function to reproductive capability.