GABA-B receptor activation inhibits the in vitro migration of malignant hepatocytes.

There are conflicting data regarding whether activation of γ-aminobutyric acid-B (GABA-B) receptors results in inhibition of tumor growth and invasion. The objectives of this study were to document the effects of the GABA-B receptor agonist baclofen on malignant hepatocyte proliferation and migration. We also sought to determine whether any effects on cell migration were mediated by changes in cyclic adenosine monophosphate (cAMP) signaling or matrix metalloproteinase (MMP) expression. Finally, GABA-B(1) and -B(2) receptor expression was documented in 2 malignant hepatocyte cell lines (PLC/PRF/5 and Huh-7) and 12 sets of human hepatocellular carcinoma and adjacent nontumor tissues. Cell proliferative activity was documented by WST-1 absorbance, migration by wound healing assays, cAMP levels by enzyme-linked immunoassay (ELISA), MMP by immunohistochemistry and ELISA, and GABA-B receptor expression by flow cytometry and reverse transcriptase - polymerase chain reaction. Although baclofen had no effect on cell proliferation, wound healing was delayed, an effect that was reversed by the GABA-B receptor antagonist CGP. cAMP levels were decreased in Huh-7 but not PLC cells exposed to baclofen. MMP expression remained unaltered in both cell lines. Finally, GABA-B(1) receptor expression was present and consistently expressed, but GABA-B(2) expression was limited and varied with the number of cell passages and (or) duration of culture. In conclusion, activation of GABA-B receptors has no effect on malignant hepatocyte proliferation but does decrease cell migration. This inhibitory effect may involve cAMP signaling but not MMP expression. GABA-B(2) receptor expression is limited and variable, which may help to explain discrepancies with previously published results.

Hepatitis B and hepatitis C viral infections in patients with chronic lymphocytic leukemia.

BACKGROUND: Whether chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infections contribute to the pathogenesis and/or course of chronic lymphocytic leukemia is unclear. OBJECTIVE: To document the prevalences of HBV and HCV infections in chronic lymphocytic leukemia patients, and to determine whether infected patients experience more aggressive disease than those without infection. METHODS: Patient sera were screened for antibodies to HBV core antigen and HCV (anti-HCV) using ELISA; both sera and peripheral blood lymphocytes were further tested (regardless of antibody results) for HBV-DNA and HCV-RNA using real-time polymerase chain reaction. Prognostic markers for chronic lymphocytic leukemia included Rai stage, IgVH mutational status, ß2-microglobulin levels, Zap-70 and CD38 status. RESULTS: Fourteen of 222 (6.3%) chronic lymphocytic leukemia patients and two of 72 (2.8%) healthy controls tested positive for previous or ongoing HBV infection (OR 2.4 [95% CI 0.5 to 7.7]; P=0.25) while four of 222 (1.8%) chronic lymphocytic leukemia patients and one of 72 (1.4%) controls tested positive for HCV markers (OR 1.3 [95% CI 0.2 to 6.4]; P=0.81). The levels and distribution of the various indicators of aggressive chronic lymphocytic leukemia disease were similar among HBV- and HCV-infected and uninfected patients. Survival times were also similar. Occult HBV and HCV infection (HBV-DNA or HCV-RNA positive in the absence of diagnostic serological markers) were uncommon in chronic lymphocytic leukemia patients (0.5% and 1.8%, respectively). CONCLUSIONS: The results of the present study do not support the hypothesis that HBV or HCV infections play an important role in the pathogenesis or course of chronic lymphocytic leukemia.

Activation of ß-adrenergic receptors increases the in vitro migration of malignant hepatocytes.

AIM: Activation of adrenergic receptors (AR) has been reported to enhance the growth and invasion of various malignancies. The effects of AR agonists on malignant hepatocyte proliferation and migration have yet to be determined. METHODS: PLC/PRF/5 (PLC) and Huh-7 cells were exposed to a wide range of concentrations of the AR agonists noradrenaline (NA) and isoprenaline. Cell proliferation, migration, intracellular cyclic adenosine monophosphate (cAMP), protein kinase A (PKA) and C (PKC), matrix metalloproteinases (MMP)-2, -3, -7 and -9, and α(1) -, ß(1) - and ß(2) -AR expression were documented in both cell lines. RESULTS: Cell proliferative activity was unaltered following exposure to physiological and stress-related concentrations of AR agonists but migration was accelerated, an effect that was inhibited by the nonselective ß-AR antagonist labetalol. cAMP, PKA, PKC or MMP expression remained unchanged. Although α(1) - and ß(1) -AR expressions were abundant, ß(2) -AR expression was limited in both cell lines. CONCLUSION: Unlike other malignancies studied to date, in this study, the proliferative activity of malignant hepatocytes was not increased by exposure to AR agonists, a finding that could be explained by downregulation of ß(2) -AR expression. The increase in malignant hepatocyte migration observed remains unexplained but does not appear to involve adenyl cyclase or MMP signaling pathways.