Fas/FasL Pathway (fas/fasl + pathway)

Distribution by Scientific Domains

Selected Abstracts

Plasma-soluble Fas (APO-1, CD95) and soluble Fas ligand in immune thrombocytopenic purpura

Chie Yoshimura
Abstract: We investigated the levels of various cytokines and soluble factors in ITP patients, in order to determine the influence of these factors on the pathogenesis of ITP. We found increases in IL-2, IL-6, IFN-,, and M-CSF levels in ITP patients compared with those in healthy individuals. On lymphocyte phenotype analysis, we found no clear difference in total T cell population (CD2+ CD19, cells) or cytotoxic T cell frequency (CD8+ CD11b, cells) between these two groups. The frequency of helper/inducer T cells (CD4+ CD8, cells) was decreased in ITP patients. There was a significant increase in activated T cells (CD3+ HLA-DR+ cells) in ITP patients. Furthermore, frequencies of NK cells of potent activity (CD16+ CD56+ cells) were significantly elevated in ITP patients. Seventeen of the 54 ITP patients (31.5%) had elevated levels of sFas, and 11 of the 54 patients (20.4%) of sFasL. In addition, a significant increase of sFasL was observed in sFas-positive ITP patients, and in these patients the sFasL level was correlated with that of sFas (r=0.687, p<0.01). We found significant increases in IL-2 and sIL-2R levels in sFas-positive ITP patients. For other factors examined, however, there were no differences in level between sFas-positive and-negative ITP patients. Percentages of activated T cells (CD3+ and HLA-DR+ cells) and NK cells (CD16+ and CD56+ cells) were significantly higher in sFas-positive ITP patients than in sFas-negative ITP patients. These findings suggests that the pathogenesis of ITP includes alteration of the Fas/FasL pathway. [source]

CC531S-induced damage of the rat liver sinusoidal endothelial lining is mediated by the Fas/FasL pathway

HEPATOLOGY, Issue 5 2003
Katrien Vekemans
No abstract is available for this article. [source]

FAP-1-mediated activation of NF-,B induces resistance of head and neck cancer to fas-induced apoptosis

Eva Wieckowski
Abstract Molecular mechanisms responsible for tumor resistance to apoptosis often involve the Fas/FasL pathway. While squamous cell carcinomas of the head and neck (SCCHN) express both Fas and FasL, their resistance to self-induced apoptosis or apoptosis mediated by Fas agonistic antibody (CH-11Ab) was independent of the level of Fas surface expression or the presence of soluble Fas in supernatants of primary or metastatic SCCHN cell lines. By in vitro immunoselection, using PCI-15A cell line treated with successive cycles of CH-11 Ab, Fas-resistant sublines with the parental genotype were selected. Such sublines failed to cleave caspase-8 upon Fas engagement and were resistant to CH-11 Ab, although they remained sensitive to VP-16 or staurosporin. In the presence of cycloheximide, the selected SCCHN sublines become susceptible to CH-11 Ab, and showed cleavage of caspase-8, suggesting that apoptosis resistance was mediated by an inhibitory protein(s) acting upstream of caspase-8. Overexpression of Fas-associated phosphatase 1 (FAP-1), but not cellular FLICE-inhibitory protein (cFLIP) in SCCHN sublines was documented by Western blots and RT-PCR analyses. The FAP-1+ selected sublines also downregulated cell surface Fas. A high phosphorylation level of I,B,, NF,B activation and upregulation of Bcl-2 expression were observed in the FAP-1+ sublines. Treatment with the phosphatase inhibitor, orthovanadate, or silencing of FAP-1 with siRNA abolished their resistance to apoptosis, suggesting that FAP-1 phosphatase activity could be responsible for NF-,B activation and resistance of SCCHN cells to Fas-mediated apoptosis. J. Cell. Biochem. 100: 16,28, 2007. 2006 Wiley-Liss, Inc. [source]

FasL/Fas pathway is involved in dengue virus induced apoptosis of the vascular endothelial cells,,

Hongwu Liao
Abstract The hallmark of the dengue hemorrhagic fever/dengue shock syndrome is hematologic abnormality. The pathogenesis of dengue hemorrhagic fever/dengue shock syndrome remains unknown. Our work showed that the dengue virus serotype-2 induced apoptosis in human umbilical vein endothelial cells. Fas (CD95), Tumor Necrosis Factor receptors, and Tumor Necrosis Factor-related apoptosis-inducing ligand receptors are the most common death receptors, which can induce apoptosis. Compared with the untreated human umbilical vein endothelial cells, Fas expression was increased both in the mRNA level and on the surface of infected human umbilical vein endothelial cells. FasL was expressed at similar levels on human umbilical vein endothelial cells over a course of dengue virus serotype-2 infection, but the expression in mRNA level was increased in infected human umbilical vein endothelial cells. It is possible that there is soluble FasL secreted from human umbilical vein endothelial cells in the supernatant. Tumor Necrosis Factor-related apoptosis-inducing ligand receptor 1 and Tumor Necrosis Factor receptors 1,2 were constantly very low, whereas Tumor Necrosis Factor-related apoptosis-inducing ligand receptors 2,4 decreased after dengue virus serotype-2 infection. This result suggested that dengue virus serotype-2 may inhibit Tumor Necrosis Factor-related apoptosis-inducing ligand receptors-induced apoptosis. The apoptotic rates in human umbilical vein endothelial cells were decreased upon the addition of caspase family inhibitors. In addition, activated caspase 8 and caspase 3 were also observed by Western blot following dengue virus serotype-2 infection. Thus, it is shown that the Fas/FasL pathway may participate in dengue virus-induced apoptosis of vascular endothelial cells in vitro. J. Med. Virol. 82:1392,1399, 2010. 2010 Wiley-Liss, Inc. [source]

CC531s colon carcinoma cells induce apoptosis in rat hepatic endothelial cells by the Fas/FasL-mediated pathway

Katrien Vekemans
Abstract The mechanisms involved in colorectal carcinoma with liver metastasis are not well known. Metastasizing colon carcinoma cells express more FasL than primary colon carcinoma cells and cancer cells induce apoptosis in hepatocytes by the Fas/FasL pathway. Therefore, this study focused on Fas/FasL expression and functionality in rat liver sinusoidal endothelial cells (LSECs) and CC531s colon carcinoma cells in vitro and in vivo. RT-PCR and immunochemistry revealed Fas and FasL in LSECs and CC531s, respectively. Functionality of Fas was assessed in vitro by incubation with human recombinant FasL (1,100 ng/ml) with or without enhancer. At concentrations of 10 and 100 ng/ml with enhancer, respectively 21% and 44% of endothelial cells showed signs of apoptosis using Hoechst 33342/propidium iodide staining and electron microscopy. In co-cultures, apoptosis could be detected in endothelial cells neighboring the CC531s and could be inhibited by an antagonistic FasL antibody. Moreover, 18 h after mesenteric injection of CC531s, the sinusoidal endothelium revealed disruption. In conclusion, (i) CC531s cells induce apoptosis in LSECs in vitro by using Fas/FasL; (ii) CC531s cells damage the sinusoidal endothelial lining in vivo; and (iii) this might provide FasL-positive tumor cells a gateway towards the hepatocytes. [source]