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1.
Functional absence of FADD in PLC/PRF/5 hepatoma cells: possible involvement in the transformation to hepatoma in HBV-infected hepatocytes. 总被引:6,自引:0,他引:6
A Suzuki T Araki M Miura Y Tsutomi 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1999,221(1):72-79
The death receptor Fas transduces apoptotic death signaling upon stimulation by Fas ligand and plays a key role in viral hepatitis. When hepatitis-B virus (HBV) infects hepatocytes, the Fas ligand/Fas system responds as the triggering machinery of hepatitis. However, some HBV-infected cells may circumvent Fas-mediated apoptosis and transform to hepatoma cells, as do PLC/PRF/5 hepatoma cells. Therefore, in the present study, we used PLC/PRF/5 hepatoma cells to investigate this ability to avoid Fas-mediated apoptosis. When the cells were treated with an agonistic Fas antibody, they showed resistance to Fas-mediated apoptosis. In contrast, HepG2 cells of the same hepatoma line succumbed. Caspase 3 and 8, which are essential regulators for Fas-mediated cell death, were expressed in both hepatoma cell lines, but only HepG2 cells showed activation of the caspases. A comparison study of expression of other death-associated factors between PLC/PRF/5 and HepG2 cells revealed no apparent differences. However, Far-Western blotting analysis using the Fas death domain (FDD) showed a significant difference. Molecular weight comparison and immunoblotting analysis revealed that PLC/PRF/5 cells lack the FDD-associated protein FADD. In addition, FDD-injected HepG2 cells showed a resistance to Fas-mediated apoptosis, and PLC/PRF/5 cells acquired Fas-sensitivity by FADD injection. Here, we propose that a functional absence of FADD is one of the pathways for the carcinogenesis of HBV-infected hepatocytes. 相似文献
2.
Jiwei Li Xiuting Zheng Ning Lou Wenbin Zhong Daoguang Yan 《Journal of lipid research》2016,57(10):1845-1853
Oxysterols are 27-carbon oxidized derivatives of cholesterol or by-products of cholesterol biosynthesis that can induce cell apoptosis in addition to a number of other bioactions. However, the mechanisms underlying this cytotoxicity are not completely understood. ORP8 is a member of the oxysterol binding protein-related protein (ORP) family, implicated in cellular lipid homeostasis, migration, and organization of the microtubule cytoskeleton. Here, we report that 25-hydroxycholesterol (OHC) induced apoptosis of the hepatoma cell lines, HepG2 and Huh7, via the endoplasmic reticulum (ER) stress response pathway, and ORP8 overexpression resulted in a similar cell response as 25-OHC, indicating a putative functional relationship between oxysterol cytotoxicity and ORP8. Further experiments demonstrated that ORP8 overexpression significantly enhanced the 25-OHC effect on ER stress and apoptosis in HepG2 cells. A truncated ORP8 construct lacking the ligand-binding domain or a closely related protein, ORP5, was devoid of this activity, evidencing for specificity of the observed effects. Importantly, ORP8 knockdown markedly dampened such responses to 25-OHC. Taken together, the present study suggests that ORP8 may mediate the cytotoxicity of 25-OHC. 相似文献
3.
Expression of Bcl—2 inhibited Fas—mediated apoptosis in human hepatocellular carcinoma BEL—7404 cells 总被引:22,自引:0,他引:22
Apoptosis plays an important role in embryonic development,tissue remodeling,immune regulation and tumor regression.Two groups of molecules(Bcl-2 family and “Death factor” family) are involved in regulating apoptosis.In order to know about the effect of Bcl-2 on apoptosis induced by Fas,a typical member of “Death factor” family,the transfection experiments with expression vectors pcDNA3-fl and pcDNA3-bcl-2 were performed in BEL-7404 cells,a human hepatocellular carcinoma cell line which expresses endogenous Fas,but not FasL and Bcl-2.The data showed that the expression of FasL in pcDNA3-fl transfected hepatoma cells obviously induced the apoptosis of the cells.However,the overexpression of Bcl-2 in pcDNA3-bcl-2 transfected 7404/b-16 cells counteracted pcDNA3-fl transient transfection mediated apoptosis.Further study by cotransfection experiments indicated that Bid but not Bax (both were pro-apoptotic proteins of Bcl-2 family) blocked the inhibitory effect of Bcl-2 on Fas-mediated apoptosis.These results suggested that Fas-mediated apoptosis in human hepatoma cells is possibly regulated by Bcl-2 family proteins via mitochondria pathway. 相似文献
4.
R S Biswas H J Cha J M Hardwick R K Srivastava 《Molecular and cellular biochemistry》2001,225(1-):7-20
Fas/Fas ligand system triggers apoptosis in many cell types. Bcl-XL overexpresion antagonizes Fas/Fas ligand-mediated cell death. The mechanism by which Bcl-XL influences Fas-mediated cell death is unclear. We have found that microtubule-damaging drugs (e.g. Paclitaxel) induce apoptosis in a Fas/FasL-dependent manner. Inhibition of Fas/FasL pathway by anti-FasL antibody, mutant Fas or a dominant negative FADD blocks paclitaxel-induced apoptosis. Paclitaxel induced apoptosis through activation of both caspase-8 and caspase-3. Overexpression of Bcl-XL leads to inhibition of paclitaxel-induced FasL expression and apoptosis. Bcl-XL prevents the nuclear translocation of NFAT (nuclear factor of activated T lymphocytes) by inhibiting the activation of calcineurin, a calcium-dependent phosphatase that must dephosphorylate NFAT for it to move to the nucleus. The loop domain in Bcl-XL can suppress the anti-apoptotic function of Bcl-XL and may be a target for regulatory post-translational modifications. Upon phosphorylation, Bcl-XL loses its ability to bind with calcineurin. Without NFAT nuclear translocation, the FasL gene is not transcribed. Thus, paclitaxel and other drugs that disturb microtubule function kill cells, at least in part, through the induction of FasL, and Bcl-XL-mediated resistance to these agents is related to failure to induce FasL expression. 相似文献
5.
Lee JK Sayers TJ Back TC Wigginton JM Wiltrout RH 《Apoptosis : an international journal on programmed cell death》2003,8(2):151-160
Lewis lung carcinoma (3LL) cells were constitutively resistant to Fas-mediated apoptosis, but overexpression of Fas on 3LL cells allowed Fas-mediated apoptosis after crosslinking with agonist anti-Fas antibody (Jo2) in vitro. Surprisingly, Fas-overexpressing 3LL cells showed enhanced in vivo tumor progression, whereas no promotion of in vivo tumor growth was observed for dominant negative (DN) Fas-overexpressing 3LL transfectants in which the cytoplasmic death domain was deleted. In addition, the promotion of in vivo tumor growth by Fas-overexpression was reduced in gld (FasL-mutation) mice compared to normal mice. These data indicate that intact Fas/FasL cell signaling is required for the promotion of in vivo tumor growth by Fas overexpression in 3LL cells. In contrast to the efficient Fas-mediated killing induced in vitro by crosslinking with anti-Fas antibody, Fas-overexpressing 3LL cells were resistant in vitro to Fas-mediated apoptosis by activated T cells or transient FasL transfection. These data suggest that agonist anti-Fas antibody and natural FasL can transmit qualitatively different signals, and crosslinking of Fas with natural FasL on 3LL cells does not deliver the expected death signal. Thus, our results demonstrate that in some cases overexpression of Fas can result in a survival advantage for tumor cells in vivo. 相似文献
6.
Hepatitis B virus X protein (HBx) plays important roles in the development of hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) contribute to cancer development by acting as oncogenes or tumor suppressors. Previously, we reported that HBx was able to promote the migration of hepatoma HepG2 cells. However, the regulation of miRNAs in the development of HBV-related HCC is poorly understood. In the present study, we reported that miR-29a was a novel regulator of migration of hepatoma cells mediated by HBx. Our data showed that the expression of miR-29a was dramatically increased in p21-HBx transgenic mice, HBx-transfected hepatoma HepG2-X (or H7402-X) cells and HepG2.2.15 cells that constitutively replicate HBV. However, our data showed that miR-29a was upregulated in 4 of the 11 clinical HCC samples. We found that the overexpression of miR-29a promoted the migration of HepG2 cells, while a specific miR-29a inhibitor could partially abolish the enhanced migration of HepG2-X cells. Moreover, we identified PTEN was one of the target genes of miR-29a in HepG2 cells. The deletion of the miR-29a-binding site was able to abolish the role of miR-29a in suppression of luciferase activity of the PTEN 3'UTR reporter. Meanwhile, the overexpression of PTEN was able to reverse the promoted migration of HepG2 cells mediated by miR-29a. Moreover, our data showed that the modulation of Akt phosphorylation, a downstream factor of PTEN, was involved in the cell migration enhanced by miR-29a, suggesting that miR-29a is responsible for the cell migration through its target gene PTEN. Thus, we conclude that miR-29a is involved in the regulation of migration of hepatoma cells mediated by HBx through PTEN in cell culture model. 相似文献
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Differential regulation and function of the Fas/Fas ligand system in human trophoblast cells 总被引:14,自引:0,他引:14
Aschkenazi S Straszewski S Verwer KM Foellmer H Rutherford T Mor G 《Biology of reproduction》2002,66(6):1853-1861
11.
Xiao S Jodo S Sung SS Marshak-Rothstein A Ju ST 《The Journal of biological chemistry》2002,277(52):50907-50913
Soluble CD95 (Fas) ligand (sFasL) is known to be deficient in transducing signals upon engagement with membrane Fas. Here we report that sFasL tranduces, in synergy with non-cytotoxic anti-Fas monoclonal antibody (mAb), signals for apoptosis and nuclear translocation of the NF-kappaB (p65/p50) heterodimer. Activation of the specific signaling pathways correlates with target Fas-associated death domain-like interleukin-1beta-converting enzyme inhibitory protein expression. Synergy with anti-Fas mAb was demonstrated with a trimeric unit of sFasL bearing a single binding site for Fas trimer. In contrast, membrane-bound FasL as expressed on cell-derived vesicles was fully competent in transducing Fas-mediated signals for apoptosis and NF-kappaB nuclear translocation. We propose a model in which the trimeric sFasL signaling requires target expression of a high focal density of Fas, which is induced by the signaling-incompetent anti-Fas mAb. Membrane-bound FasL induces powerful Fas-mediated signals because it possesses both Fas-focusing and signal-transducing functions. 相似文献
12.
Stel AJ Ten Cate B Jacobs S Kok JW Spierings DC Dondorff M Helfrich W Kluin-Nelemans HC de Leij LF Withoff S Kroesen BJ 《Journal of immunology (Baltimore, Md. : 1950)》2007,178(4):2287-2295
Ab binding to CD20 has been shown to induce apoptosis in B cells. In this study, we demonstrate that rituximab sensitizes lymphoma B cells to Fas-induced apoptosis in a caspase-8-dependent manner. To elucidate the mechanism by which Rituximab affects Fas-mediated cell death, we investigated rituximab-induced signaling and apoptosis pathways. Rituximab-induced apoptosis involved the death receptor pathway and proceeded in a caspase-8-dependent manner. Ectopic overexpression of FLIP (the physiological inhibitor of the death receptor pathway) or application of zIETD-fmk (specific inhibitor of caspase-8, the initiator-caspase of the death receptor pathway) both specifically reduced rituximab-induced apoptosis in Ramos B cells. Blocking the death receptor ligands Fas ligand or TRAIL, using neutralizing Abs, did not inhibit apoptosis, implying that a direct death receptor/ligand interaction is not involved in CD20-mediated cell death. Instead, we hypothesized that rituximab-induced apoptosis involves membrane clustering of Fas molecules that leads to formation of the death-inducing signaling complex (DISC) and downstream activation of the death receptor pathway. Indeed, Fas coimmune precipitation experiments showed that, upon CD20-cross-linking, Fas-associated death domain protein (FADD) and caspase-8 were recruited into the DISC. Additionally, rituximab induced CD20 and Fas translocation to raft-like domains on the cell surface. Further analysis revealed that, upon stimulation with rituximab, Fas, caspase-8, and FADD were found in sucrose-gradient raft fractions together with CD20. In conclusion, in this study, we present evidence for the involvement of the death receptor pathway in rituximab-induced apoptosis of Ramos B cells with concomitant sensitization of these cells to Fas-mediated apoptosis via Fas multimerization and recruitment of caspase-8 and FADD to the DISC. 相似文献
13.
A functional immune system not only requires rapid expansion of antigenic specific T cells, but also requires efficient deletion of clonally expanded T cells to avoid accumulation of T cells. Fas/Fas ligand (FasL)-mediated apoptosis plays a critical role in the deletion of activated peripheral T cells, which is clearly demonstrated by superantigen-induced expansion and subsequent deletion of T cells. In this study, we show that in the absence of protein kinase C-theta (PKC-theta), superantigen (staphylococcal enterotoxin B)-induced deletion of Vbeta8(+) CD4(+) T cells was defective in PKC-theta(-/-) mice. In response to staphylococcal enterotoxin B challenge, up-regulation of FasL, but not Fas, was significantly reduced in PKC-theta(-/-) mice. PKC-theta is thus required for maximum up-regulation of FasL in vivo. We further show that stimulation of FasL expression depends on PKC-theta-mediated activation of NF-AT pathway. In addition, PKC-theta(-/-) T cells displayed resistance to Fas-mediated apoptosis as well as activation-induced cell death (AICD). In the absence of PKC-theta, Fas-induced activation of apoptotic molecules such as caspase-8, caspase-3, and Bid was not efficient. However, AICD as well as Fas-mediated apoptosis of PKC-theta(-/-) T cells were restored in the presence of high concentration of IL-2, a critical factor required for potentiating T cells for AICD. PKC-theta is thus required for promoting FasL expression and for potentiating Fas-mediated apoptosis. 相似文献
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Microcystin-LR (MC-LR) is the most frequent and most toxic microcystin identified. This natural toxin has multiple features, including inhibitor of protein phosphatases 1 and 2A, inducer of oxidative stress, as well as, tumor initiator and promoter. One unique character of MC-LR is this chemical can accumulate into liver after contacting and lead to severe damage to hepatocytes, such as apoptosis. Fas receptor (Fas) and Fas ligand (FasL) system is a critical signaling system initiating apoptosis. In current study, we explored whether MC-LR could induce Fas and FasL expression in HepG2 cells, a well used in vitro model for the study of human hepatocytes. The data showed MC-LR induced Fas and FasL expression, at both mRNA and protein levels. We also found MC-LR induced apoptosis at the same incubation condition at which it induced Fas and FasL expression. The data also revealed MC-LR promoted nuclear translocation and activation of p65 subunit of NF-κB. By applying siRNA to knock down p65 in HepG2 cells, we successfully impaired the activation of NF-κB by MC-LR. In these p65 knockdown cells, we also observed significant reduction of MC-LR-induced Fas expression, FasL expression, and apoptosis. These findings demonstrate that the NF-κB mediates the induction of Fas and FasL as well as cellular apoptosis by MC-LR in HepG2 cells. The results bring important information for understanding how MC-LR induces apoptosis in hepatocytes. 相似文献
16.
Wenbin Zhong You Zhou Jiwei Li Raghavendra Mysore Wei Luo Shiqian Li Mau-Sun Chang Vesa M. Olkkonen Daoguang Yan 《Experimental cell research》2014
We earlier identified OSBP-related protein 8 (ORP8) as an endoplasmic reticulum/nuclear envelope oxysterol-binding protein implicated in cellular lipid homeostasis, migration, and organization of the microtubule cytoskeleton. Here, a yeast two-hybrid screen identified Homo sapiens sperm associated antigen 5 (SPAG5)/Astrin as interaction partner of ORP8. The putative interaction was further confirmed by pull-down and co-immunoprecipitation assays. ORP8 did not colocalize with kinetochore-associated SPAG5 in mitotic HepG2 or HuH7 cells, but overexpressed ORP8 was capable of recruiting SPAG5 onto endoplasmic reticulum membranes in interphase cells. In our experiments, 25-hydroxycholesterol (25OHC) retarded the HepG2 cell cycle, causing accumulation in G2/M phase; ORP8 overexpression resulted in the same phenotype. Importantly, ORP8 knock-down dramatically inhibited the oxysterol effect on HepG2 cell cycle, suggesting a mediating role of ORP8. Furthermore, knock-down of SPAG5 significantly reduced the effects of both ORP8 overexpression and 25OHC on the cell cycle, placing SPAG5 downstream of the two cell-cycle interfering factors. Taken together, the present results suggest that ORP8 may via SPAG5 mediate oxysterol interference of the HepG2 cell cycle. 相似文献
17.
The contribution of Fas-mediated death pathway to doxorubicin-induced death of MCF-7 cells is not unambiguously elucidated. Thus, this study was conducted to explore doxorubicin-induced Fas/FasL signaling pathway activation in MCF-7 cells and doxorubicin-resistant MCF-7 (MCF-7/Dox) cells. Doxorubicin-induced caspase-8 activation was found to be mediated through Akt/ERK inactivation and FasL-independent Fas pathway in MCF-7 cells, while caspase-8 activation in MCF-7/Dox cells depended exclusively on FasL-stimulated Fas pathway. Suppression of caspase-8 activation restored the viability of doxorubicin-treated MCF-7 cells and MCF-7/Dox cells. Contrary to FasL surface expression exclusively detected in MCF-7/Dox cells, intracellular FasL expression was noted with MCF-7 cells. Promotion of FasL translocation to the cell surface by lysophosphatidic acid evoked a FasL-activated Fas death pathway in MCF-7 cells. Doxorubixin-evoked β-TrCP up-regulation promoted Sp1 degradation, which subsequently suppressed ADAM10 expression in MCF-7 and MCF-7/Dox cells. Doxorubicin-induced down-regulation of ADAM10 reduced FasL shedding, leading to Fas pathway activation in MCF-7/Dox cells. Knock-down of ADAM10 induced death in MCF-7/Dox cells, but marginally reduced the viability of MCF-7 cells. Taken together, our data indicate that Akt/ERK-mediated caspase-8 activation and Fas/FasL-mediated caspase-8 activation mostly elucidate doxorubicin-induced death in MCF-7 cells and MCF-7/Dox cells, respectively. These observations suggest a promising therapeutic modality for overcoming doxorubicin-resistant breast cancer by targeting ADAM10 sheddase activity. 相似文献
18.
目的探讨Fas/FasL(Fas配体)在原发性肝细胞肝癌(HCC)组织中的表达及其与乙肝病毒(HBV)感染的关系。方法用免疫组化S-P法检测21例肝癌组织及其10例癌旁组织Fas/FasL的表达。结果在肝癌和癌旁组织中Fas表达的阳性率分别为52.38%和80.00%(P〈0.05),FasL分别为66.67%和40.00%(P〈0.05)。在HBsAg阳性和阴性组Fas表达的阳性率分别为50.00%和66.67%(P〉0.05);FasL分别为61.11%和100%(P〈0.05)。肝癌组织中Fas、FasL表达与性别、年龄、肿瘤大小无关,与癌栓转移呈负相关,FasL与分化程度有关。结论肝癌细胞能下调Fas及上调FasL的表达而使凋亡受阻,HBV感染能抑制肝癌组织FasL的表达,可能是HBV在HCC的发牛及发展讨稃中的致痛机制。 相似文献
19.
The Fas/FasL system has been suggested to play an important role in the establishment of immune privilege status for tumors
by inducing Fas-mediated apoptosis in tumor-specific lymphocytes. However, the role of cell-surface expressed FasL in tumor
cell protection has recently become controversial.
Our laboratory has focused on the study of the role of the Fas/FasL system in the normal tissue remodeling of the female reproductive
tract and in immune-privileged organs. Our studies have demonstrated a connection between sex hormones and the regulation
of the Fas/FasL pathway in immune and reproductive cells. More recently, we have investigated the resistance of tumor cells
to Fas-mediated apoptosis. We have also characterized a new form of FasL, different from the classical membranal form, which
is secreted by ovarian cancer cells. In this review we describe the main techniques used in these studies. 相似文献
20.
Localization of Fas/CD95 into the lipid rafts on down-modulation of the phosphatidylinositol 3-kinase signaling pathway 总被引:1,自引:0,他引:1
Bénéteau M Pizon M Chaigne-Delalande B Daburon S Moreau P De Giorgi F Ichas F Rebillard A Dimanche-Boitrel MT Taupin JL Moreau JF Legembre P 《Molecular cancer research : MCR》2008,6(4):604-613
Activation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway is known to protect tumor cells from apoptosis and more specifically from the Fas-mediated apoptotic signal. The antitumoral agent edelfosine sensitizes leukemic cells to death by inducing the redistribution of the apoptotic receptor Fas into plasma membrane subdomains called lipid rafts. Herein, we show that inhibition of the PI3K signal by edelfosine triggers a Fas-mediated apoptotic signal independently of the Fas/FasL interaction. Furthermore, similarly to edelfosine, blockade of the PI3K activity, using specific inhibitors LY294002 and wortmannin, leads to the clustering of Fas whose supramolecular complex is colocalized within the lipid rafts. These findings indicate that the antitumoral agent edelfosine down-modulates the PI3K signal to sensitize tumor cells to death through the redistribution of Fas into large platform of membrane rafts. 相似文献