No abstract

Background: Hepatitis C virus (HCV) infection is a major cause of human hepatocellular carcinoma (HCC). The precise mechanism of hepatocarcinogenesis in humans by HCV is currently unclear. It was recently shown, however, that transgenic mice with the HCV core gene often develop HCC, suggesting tumorigenic activity of the HCV core protein. Further, the HCV core protein expressed in HepG2 cells transfected with the core gene was shown to stimulate proliferation of transfectants through activation of nuclear factor-kB (NF-kB). The downstream target molecule(s) of NF-kB activated by the HCV core protein to evoke cell proliferation is not yet identified. Transforming growth factor (TGF) a, which is often overexpressed in various tumour tissues such as HCC, has been shown to stimulate hepatocyte proliferation through activation of the mitogen-activated protein kinase or extracellular signal-related protein kinase (MAPK/ ERK) cascade. Aims: To explore the possibility that TGFa might be a target molecule for NF-kB activated by the HCV core, and that TGFa participates in the growth promotion of the core transfectants in an autocrine manner, activating the MAPK/ERK pathway. Methods: A HCV core expression vector was transfected into human hepatoma Huh-7, HepG2 and Hep3B cells. NF-kB activity was examined by an electrophoretic mobility shift assay. TGFa transcription was assessed by a luciferase reporter assay. TGFa protein was determined by immunoblot and ELISA. MAPK/ ERK activity was examined by an in vitro kinase assay. Cell proliferation was assessed by a water-soluble tetrazolium salt-1 assay. Results: In the HCV core transfectants, NF-kB bound to the kB site in the TGFa proximal promoter region, resulting in an increase in TGFa transcription. Immunoblot as well as ELISA showed increased TGFa expression in the HCV core transfectants. SN50, a specific inhibitory peptide for NF-kB, cancelled HCV core-induced TGFa expression. HCV core protein increased cell proliferation as well as ERK activity of the HCV core transfectants as compared with the mock transfectants. The growth-promoting activity and activation of ERK by the HCV core protein were negated by treatment with anti-TGFa antibodies. Conclusions: These results suggest that the HCV core protein promotes proliferation of human hepatoma cells by activation of the MAPK/ERK pathway through up regulation of TGFa transcription via activation of NF-kB. Our finding provides a new insight into the mechanism of hepatocarcinogenesis by HCV infection.

Sphingosine 1-phosphate (S1P) regulates lymphocyte trafficking through the type 1 sphingosine 1-phosphate receptor (S1P1) and participates in many pathological conditions, including autoimmune diseases. We developed a novel S1P1-selective antagonist, TASP0277308, which is structurally unrelated to S1P. This antagonist competitively inhibited S1P-induced cellular responses, such as chemotaxis and receptor internalization. Furthermore, differing from previously reported S1P1 antagonists, TASP0277308 demonstrated in vivo activities to induce lymphopenia, a block in T cell egress from the thymus, displacement of marginal zone B cells, and upregulation of CD69 expression on both T and B cells, all of which recapitulate phenotypes of S1P1-deficient lymphocytes. In a mouse collagen-induced arthritis model, TASP0277308 significantly suppressed the development of arthritis, even after the onset of disease. These findings provide the first chemical evidence to our knowledge that S1P1 antagonism is responsible for immunosuppression in the treatment of autoimmune diseases and also resolve the discrepancies between genetic and chemical studies on the functions of S1P1 in lymphocytes.

Our results suggest the possibility that HEV infection is circulating in Japan at a low level. HEV infection was associated with male sex, but not with HAV infection.

The effect of oral dissolution therapy for pancreatic stones was evaluated in patients with chronic calcific pancreatitis. The anti-epileptic agent trimethadione was given orally to 30 outpatients at a dose of 0.9-1.5 g daily. On plain X-ray films and CT scans of the abdomen, pancreatic stones began to be dissolved around 8 months of treatment, and diminished in size and number or disappeared in 21 patients (70%) during the mean follow-up period of 32 months. The effect of trimethadione treatment on dissolution of stones was not closely related to the aetiology of the disease, distribution and size of stones, previous history of surgical interventions, or the degree of pancreatic dysfunctions. In three patients who stopped this medication of their own accord, pancreatic stones re-increased or reappeared about 6 months later. During trimethadione treatment, impaired exocrine pancreatic function returned to normal in four of nine patients examined, and diabetes mellitus was well controlled by either diet therapy alone or oral hypoglycaemic agents in eight of 10 patients who did not need insulin before trimethadione treatment. Complete relief of pain was noted in 73% of patients during the treatment. Overall gains and no change in bodyweight were observed in 83% of patients. Mild photophobia was the most common side effect, but could be easily overcome by wearing sunglasses. No severe side effects were observed in the liver, kidney, blood or the eyeground. Pancreatic stones in 30 patients not treated with trimethadione neither disappeared nor diminished spontaneously. Trimethadione treatment may be a useful tool for chemical dissolution of pancreatic stones.