Expression of cyclooxygenase 2 and cytosolic phospholipase A(2) in the liver tissue of patients with chronic hepatitis and liver cirrhosis.

Cyclooxgenase (COX) and phospholipase A(2) (PLA(2)) are crucial rate-limiting enzymes involved in the conversion of arachidonic acid to prostaglandin H(2), the precursor of various compounds including prostaglandins (PGs), prostacyclin, and thromboxanes in the process of PGs' synthesis. Recent studies have shown increased levels of COX(2) in adjacent cirrhotic tissue of hepatocellular carcinoma. The relationship between the expression of COX(2) or cytosolicPLA(2) (cPLA(2)) and liver fibrosis has not been described previously. We used 45 formalin-fixed, paraffin-embedded liver tissue samples obtained by needle biopsies from patients with chronic hepatitis, consisting of 7 cases of F(0), 10 cases of F(1), 10 cases of F(2), 9 cases of F(3) and 9 cases of liver cirrhosis (LC) according to the New Inuyama Classification of the staging of liver fibrosis. The expression of COX(2) and cPLA(2) was investigated by immunohistochemistry, western blotting and image analysis. The positive signals for COX(2) and cPLA(2) were observed in the cytoplasm of hepatocytes. The signal intensity of COX(2) increased significantly with the progression of liver fibrosis (P<0.001) and no significant difference was observed in the relative amount of cPLA(2) from group F(0) to group LC. According to the New Inuyama Classification of hepatitis activity grading, 45 samples were classified as group A(1) (23 cases), group A(2) (19 cases) and group A(3) (3 cases). No significant differences were found in the relative amount of COX(2) and cPLA(2) between group A(1) and group A(2-3). Significant correlation was observed between the relative amount of COX(2) and hyaluronan (P<0.01). Our findings suggested that COX(2) may be involved in liver fibrogenesis.

Evaluation of interleukin-12-induced interferon-y production in vitro by peripheral blood mononuclear cells in patients with chronic liver disease.

BACKGROUND/AIMS: Interleukin-12 plays an important role in anti-tumor immune response by induction of interferon-gamma production by T cells and NK cells, and by activation of cytotoxic T cells and NK cells. We evaluated interleukin-12-induced interferon-gamma production as one of the immunological markers of patients with chronic liver diseases. METHODOLOGY: Interleukin-12-induced interferon-gamma production was measured in vitro in peripheral blood mononuclear cells from 28 hepatocellular carcinoma patients, 10 liver cirrhosis patients, 14 chronic hepatitis patients and 16 healthy individuals. RESULTS: The hepatocellular carcinoma patients exhibited a reduced interleukin-12 responsiveness for interferon-gamma production compared to the liver cirrhosis patients, the chronic hepatitis patients and the healthy individuals. The reduced interferon-gamma production seemed to roughly reflect clinical stage in the hepatocellular carcinoma patients. The interferon-gamma production correlated with neither alpha-fetoprotein nor protein induced by vitamin K absence II. CONCLUSIONS: The level of interleukin-12-induced interferon-gamma production by peripheral blood mononuclear cells in the patients with hepatocellular carcinoma was significantly lower than that in the patients with liver cirrhosis which is thought to be a premalignant state. The measurement of interferon-gamma production may be useful in evaluating severity of chronic liver disease from an immunological point of view.

NS-398, a selective cyclooxygenase 2 inhibitor, inhibited cell growth and induced cell cycle arrest in human hepatocellular carcinoma cell lines.

Cyclooxygenase 2 (COX-2) has been suggested to be associated with liver carcinogenesis. Several reports have shown that NSAIDs inhibit the growth of hepatocellular carcinoma cell lines. There is little evidence of how COX-2 inhibitors regulate the proliferation of hepatocellular carcinoma cells or the mechanism involved. In our study, we investigated the growth-inhibitory mechanism of a selective COX-2 inhibitor, NS-398, in 4 hepatocellular carcinoma cell lines by studying cell growth, COX-2 and proliferating cell nuclear antigen (PCNA) expression, cell cycle distribution and the evidence of apoptosis. NS-398 inhibited the growth of all 4 cell lines in a time- and dose-dependent manner and the inhibitory effects were independent of the level of COX-2 protein expression. PCNA expression was downregulated by NS-398 in a dose-independent manner. NS-398 caused cell cycle arrest in the S phase with a reduction in cell numbers and cell accumulation in the G0/G1 phase, for all 4 cell lines. No evidence of apoptosis was observed in our present study. Our findings suggest that a selective COX-2 inhibitor might serve as an effective tool for the chemoprevention and treatment of hepatocellular carcinomas. A reduction in cell number in the S phase may be an important event in cell cycle arrest caused by NS-398 in hepatocellular carcinoma cell lines.