No abstract

Transforming growth factor-beta1 (TGF-beta1) has been implicated in tumor progression. The relationship of this cytokine as measured in plasma to anti-tumor immunity and prognosis was investigated. This study consisted of 70 consecutive patients with unresectable hepatocellular carcinoma (HCC) (median age, 65 years). Forty-four healthy age-matched subjects and 32 patients with cirrhosis but no carcinoma served as controls. Patients with HCC were divided into those with plasma TGF-beta1 concentrations above (group A, n=21) or below (group B, n=49) 10 ng/ml (the mean concentration+2SD in the concentrations of the controls with cirrhosis was 8.7 ng/ml). Age, gender, Child-Pugh grade, and tumor stage distributions were similar in groups A and B. Considering all tumor stages together and individually, group A had a significantly shorter survival (median for all stages, 2 months) than group B (median for all stages, 10 months; P<0.01, generalized Wilcoxon's test). Groups A and B had significantly shorter survival than controls with cirrhosis (P<0.001 for each). Lymphokine-activated killer (LAK) activity in group A was significantly lower than that in group B (P<0.001). Natural killer (NK) activity in group A was also significantly lower than that in group B (P<0.05). Plasma TGF-beta1 concentration was a significant predictor of survival by Cox's proportional-hazards regression analysis (multivariate analysis, P<0.01). LAK and NK activities were also weak but significant predictors (P<0.05 and <0.05, respectively). These data suggest that plasma TGF-beta1 concentration is a predictor of outcome of patients with unresectable HCC. Circulating TGF-beta1 supposedly contributes to the suppression of anti-tumor immunity in the advanced disease.

The natural course of hepatitis C virus (HCV) infection has not been fully elucidated. To investigate whether HCV is spontaneously eliminated in chronic carriers, a long-term population-based cohort study was conducted on 435 chronic HCV carriers. Individual characteristics, serum HCV RNA, and liver function tests were analyzed, and ultra sonography (US) was performed in all subjects. Subjects were followed up for 7.2 +/- 2.4 years (mean +/- SD). Serum HCV RNA was spontaneously eliminated in 16/435 (3.7%) individuals during this period; thus, the incidence of spontaneous elimination of serum HCV RNA was 0.5%/year/person. Multivariate analysis revealed that both a low value of ZTT and no US finding of chronic liver disease were associated with spontaneous viral elimination in HCV carriers. Three of these 16 individuals had chronic hepatitis, and 13 of them had normal ALT levels. When the neutralization of binding (NOB) assay that evaluates inhibition of the HCV envelope-2 protein binding to human cells was examined using sera from these 16 individuals, the NOB antibody was detected in only 3 cases with chronic hepatitis. These results suggest that serum HCV RNA is spontaneously eliminated in chronic HCV carriers in a population, and that the development of NOB antibody is associated with a natural resolution of chronic hepatitis in the minority of them.

No abstract

In contrast to mammals, higher plants have evolved to express diverse protein phosphatase 2Cs (PP2Cs). Of all Arabidopsis thaliana PP2Cs, members of PP2C subfamily A, including ABI1, have been shown to be key negative regulators of abscisic acid (ABA) signalling pathways, which regulate plant growth and development as well as tolerance to adverse environmental conditions. However, little is known about the enzymatic and signalling roles of other PP2C subfamilies. Here, we report a novel Arabidopsis subfamily E PP2C gene, At3g05640, designated AtPP2CF1. AtPP2CF1 was dramatically expressed in response to exogenous ABA and was expressed in vascular tissues and guard cells, similar to most subfamily A PP2C genes. In vitro enzymatic activity assays showed that AtPP2CF1 possessed functional PP2C activity. However, yeast two-hybrid analysis revealed that AtPP2CF1 did not interact with PYR/PYL/RCAR receptors or three SnRK2 kinases, which are ABI1-interacting proteins. This was supported by homology-based structural modelling demonstrating that the putative active- and substrate-binding site of AtPP2CF1 differed from that of ABI1. Furthermore, while overexpression of ABI1 in plants induced an ABA-insensitive phenotype, Arabidopsis plants overexpressing AtPP2CF1 (AtPP2CF1oe) were weakly hypersensitive to ABA during seed germination and drought stress. Unexpectedly, AtPP2CF1oe plants also exhibited increased biomass yield, mainly due to accelerated growth of inflorescence stems through the activation of cell proliferation and expansion. Our results provide new insights into the physiological significance of AtPP2CF1 as a candidate gene for plant growth production and for potential application in the sustainable supply of plant biomass.