The polypeptide encoded by the cDNA for human cell surface antigen Fas can mediate apoptosis

Single nucleotide polymorphisms of the Fas gene are associated with papillary thyroid cancer

OBJECTIVES

Fas is the prototypic representative of the death receptor subgroup of the tumor necrosis factor (TNF) receptor family. Recently, single nucleotide polymorphisms (SNPs) of the Fas or Fas ligand (FasL) genes have been shown to be associated with an increased risk of several cancers and with the prognosis of several cancers. The objective of this study was to evaluate the association between the SNPs of the Fas and FasL genes and papillary thyroid cancer (PTC) and to assess the relationship between these SNPs and the clinicopathological characteristics of PTC.

METHODS

Five SNPs located within the two genes of Fas and FasL were genotyped using direct sequencing in 94 patients with PTC and 364 healthy controls. Genetic data were analyzed using commercially available software. And, the statistical analyses were performed according to clinicopathologic characteristics of PTC.

RESULTS

Genotyping analysis demonstrated that the intron SNP (rs1571013), promoter SNP (rs1800682) and 3'-UTR SNP (rs1468063) of Fas were significantly associated with the development of PTC. We also detected a significant difference between patients with PTC and healthy controls with respect to Fas gene allele frequencies. Furthermore, we found that the 3'-UTR SNP (rs1468063) of Fas was associated with the multifocality of cancer [dominant model, OR 0.28, p=0.028; log-additive model, OR 0.43, p=0.033].

CONCLUSION

We observed a significant association between SNPs of the Fas gene and the development of PTC. In addition, there was a significant association between a Fas SNP and the multifocality of PTC.

Cumulus cells accelerate oocyte aging by releasing soluble Fas ligand in mice

Although previous studies have suggested that cumulus cells (CCs) accelerate oocyte aging by secreting soluble and heat-sensitive paracrine factors, the factors involved are not well characterized. Because Fas-mediated apoptosis represents a major pathway in induction of apoptosis in various cells, we proposed that CCs facilitate oocyte aging by releasing soluble Fas ligand (sFasL). In this study, we reported that when the aging of freshly ovulated mouse oocytes were studied in vitro, both the apoptotic rates of CCs and the amount of CCs produced sFasL increased significantly with the culture time. We found that oocytes expressed stable levels of Fas receptors up to 24 h of in vitro aging. Moreover, culture of cumulus-denuded oocytes in CCs-conditioned CZB medium (CM), in CZB supplemented with recombinant sFasL, or in CM containing sFasL neutralizing antibodies all showed that sFasL impaired the developmental potential of the oocytes whereas facilitating activation and fragmentation of aging oocytes. Furthermore, CCs from the FasL-defective gld mice did not accelerate oocyte aging due to the lack of functional FasL. In conclusion, we propose that CCs surrounding aging oocytes released sFasL in an apoptosis-related manner, and the released sFasL accelerated oocyte aging by binding to Fas receptors.

Upregulation of the sFas/sFasL system in psoriatic patients

PURPOSE

Psoriasis is a chronic, recurrent, inflammatory disease. Recent investigations indicate its autoimmune pathogenesis. Apoptosis plays an important role in the development of many autoimmune diseases. The aim of this study was to evaluate the influence of topical treatment of psoriasis on soluble Fas (sFas) and soluble Fas-ligand (sFasL).

MATERIAL/METHODS

Serum concentrations of sFas and sFasL were measured using ELISA in 40 psoriatic patients before and after topical treatment with dithranol and compared to the values obtained from 16 healthy subjects. Data were analyzed with respect to severity of psoriasis, duration of the disease and coexisting obesity, diabetes and hypertension.

RESULTS

We found that serum levels of sFas before (11.9±2.4ng/mL) and after treatment (12.2±2.5ng/mL) were significantly higher in patients with psoriasis as compared to the control group (6.4±1.8ng/mL). Concentrations of sFasL did not differ significantly from healthy subjects, but increased after treatment. The sFas/sFasL ratio was significantly higher in psoriasis (128±47) than in the control group and, even though it tended to decrease after treatment, it still remained higher than in the control group (65±22). Additionally we observed a positive correlation of sFas/sFasL ratio with the age of patients and duration of the disease. Psoriatic patients suffering from hypertension and overweight had significantly higher sFas/sFasL ratio than other psoriatic patients.

CONCLUSIONS

Our data indicate upregulation of the sFas/sFasL system in psoriatic patients. We demonstrate association of sFas/sFasL with commorbidities - components of metabolic syndrome.

MicroRNA 196B regulates FAS-mediated apoptosis in colorectal cancer cells

Using miRNA microarray analysis, we identified 31 miRNAs that were significantly up-regulated or down-regulated in colon cancer tissues. We chose MIR196B, which was specifically up-regulated in colon cancer, for further study. We identified 18 putative MIR196B target genes by comparing between the mRNAs down-regulated in MIR196B-overexpressed cells and the assumed MIR196B target genes predicted by public bioinformatics tools. The association between MIR196B and FAS was verified in this study. FAS expression was constitutively elevated in normal human colorectal tissues. However, its expression was often reduced in human colorectal cancer. The decrease in FAS expression could be responsible for the reduction of apoptosis in colorectal cancer cells. In colorectal cancer tissue, we showed that MIR196B up-regulation was mutually followed by down regulation of FAS expression. We also showed that MIR196B directly repressed FAS expression in colorectal cells. Furthermore, anti-MIR196B up-regulated FAS expression and increased apoptosis in colorectal cancer cell lines. Our results suggest that the up-regulation of MIR196B modulates apoptosis in colorectal cancer cells by partially repressing FAS expression and that anti-MIR196B could be a potential candidate as an anti-cancer drug in colorectal cancer therapy.

Association between the CTLA-4, CD226, FAS polymorphisms and rheumatoid arthritis susceptibility: a meta-analysis

OBJECTIVE

We explored whether cytotoxic T lymphocyte antigen-4 (CTLA-4) rs5742909, CD226 rs763361, FAS rs1800682, and FASL rs763110 polymorphisms are associated with rheumatoid arthritis (RA).

METHODS

We performed a meta-analysis on the association between the four gene polymorphisms and RA.

RESULTS

Nineteen studies were included in the meta-analysis. Meta-analysis of all study subjects showed no association between RA and the CTLA-4 rs5742909 T allele (OR=1.057, 95% CI=0.782-1.429, p=0.719). However, the meta-analysis revealed an association between RA and the CD226 rs763361 T allele in all study subjects (OR=1.294, 95% CI=1.063-1.576, p=0.010), and an association was found between the CD226 rs763361 TT genotype and RA in Asians (OR=1.363, 95% CI=1.126-1.651, p=0.001). Meta-analysis showed no association between RA and the FAS rs1800682 G/A polymorphism. However, meta-analysis revealed an association between RA and the FASL rs763110 T allele in all study subjects (OR=1.366, 95% CI=1.093-1.707, p=0.006) and in Asians (OR=1.402, 95% CI=1.059-1.855, p=0.014).

CONCLUSIONS

Our meta-analysis demonstrates that the CD226 rs763361 and FASL rs763110 polymorphisms are associated with RA, especially in Asians.

Major pathways of polymyxin-induced apoptosis in rat kidney proximal tubular cells

Identifying the pathways involved in the apoptotic cell death that is associated with polymyxin-induced nephrotoxicity is crucial for the development of strategies to ameliorate this dose-limiting side effect and for the development of novel safer polymyxins. The primary aim of this study was to identify the major pathways which lead to polymyxin-induced apoptosis in cultured rat kidney proximal tubular cells (NRK-52E). Caspase-3, -8, and -9 were activated by polymyxin B treatment in a concentration-dependent manner. Concentration- and time-dependent expression of FasL and deformation of mitochondrial morphology were revealed following polymyxin B treatment. The proportion of cells with filamentous mitochondria (regular morphology) following an 8-h treatment with 1.0 mM polymyxin B was 56.2% ± 9.7% (n = 3). This was decreased to 30.7% ± 7.5% when the polymyxin B concentration was increased to 2.0 mM. The mitochondrial membrane potential (Δψm) decreased to 14.1% ± 2.9% in the cells treated with 1.0 mM polymyxin B for 24 h (n = 3) compared to that in the untreated control group. Concomitantly, concentration- and time-dependent production of mitochondrial superoxide was also observed. This study is the first to have demonstrated that polymyxin-induced apoptosis is mediated through both the death receptor and mitochondrial pathways in cultured renal tubular cells. It provides key information not only for the amelioration of polymyxin-induced nephrotoxicity but also for the discovery of novel safer polymyxin-like antibiotics against Gram-negative "superbugs."

Oxysterol-binding protein-related protein 8 (ORP8) increases sensitivity of hepatocellular carcinoma cells to Fas-mediated apoptosis

Human hepatoma (HCC) has been reported to be strongly resistant to Fas-mediated apoptosis. However, the underlying mechanisms are poorly understood. In this study the function of oxysterol-binding protein-related protein 8 (ORP8) in human hepatoma cells apoptosis was assessed. We found that ORP8 is down-regulated, whereas miR-143, which controls ORP8 expression, is up-regulated in clinical HCC tissues as compared with liver tissue from healthy subjects. ORP8 overexpression triggered apoptosis in primary HCC cells and cell lines, which coincided with a relocation of cytoplasmic Fas to the cell plasma membrane and FasL up-regulation. Co-culture of HepG2 cells or primary HCC cells with Jurkat T-cells or T-cells, respectively, provided further evidence that ORP8 increases HCC cell sensitivity to Fas-mediated apoptosis. ORP8-induced Fas translocation is p53-dependent, and FasL was induced upon ORP8 overexpression via the endoplasmic reticulum stress response. Moreover, ORP8 overexpression and miR-143 inhibition markedly inhibited tumor growth in a HepG2 cell xenograft model. These results indicate that ORP8 induces HCC cell apoptosis through the Fas/FasL pathway. The role of ORP8 in Fas translocation to the plasma membrane and its down-regulation by miR-143 offer a putative mechanistic explanation for HCC resistance to apoptosis. ORP8 may be a potential target for HCC therapy.

Lipid rafts as major platforms for signaling regulation in cancer

Cell signaling does not apparently occur randomly over the cell surface, but it seems to be integrated very often into cholesterol-rich membrane domains, termed lipid rafts. Membrane lipid rafts are highly ordered membrane domains that are enriched in cholesterol, sphingolipids and gangliosides, and behave as major modulators of membrane geometry, lateral movement of molecules, traffic and signal transduction. Because the lipid and protein composition of membrane rafts differs from that of the surrounding membrane, they provide an additional level of compartmentalization, serving as sorting platforms and hubs for signal transduction proteins. A wide number of signal transduction processes related to cell adhesion, migration, as well as to cell survival and proliferation, which play major roles in cancer development and progression, are dependent on lipid rafts. Despite lipid rafts harbor mainly critical survival signaling pathways, including insulin-like growth factor I (IGF-I)/phosphatidylinositol 3-kinase (PI3K)/Akt signaling, recent evidence suggests that these membrane domains can also house death receptor-mediated apoptotic signaling. Recruitment of this death receptor signaling pathway in membrane rafts can be pharmacologically modulated, thus opening up the possibility to regulate cell demise with a therapeutic use. The synthetic ether phospholipid edelfosine shows a high affinity for cholesterol and accumulates in lipid rafts in a number of malignant hematological cells, leading to an efficient in vitro and in vivo antitumor activity by inducing translocation of death receptors and downstream signaling molecules to these membrane domains. Additional antitumor drugs have also been shown to act, at least in part, by recruiting death receptors in lipid rafts. The partition of death receptors together with downstream apoptotic signaling molecules in membrane rafts has led us to postulate the concept of a special liquid-ordered membrane platform coined as "cluster of apoptotic signaling molecule-enriched rafts" (CASMER), referring to raft platforms enriched in apoptotic molecules. CASMERs act as scaffolds for apoptosis signaling compartmentalization, facilitating and stabilizing protein-protein interactions by local assembly of cross-interacting molecules, which leads to apoptosis amplification and a decrease in apoptotic signal threshold. Edelfosine also displaced survival PI3K/Akt signaling from lipid rafts, leading to Akt inhibition, in mantle cell lymphoma cells. Thus, membrane rafts could act as scaffold structures where segregation of pro- from anti-apoptotic molecules could take place. In this review, we summarize our view of how reorganization of the protein composition of lipid raft membrane domains regulates cell death and therefore it might be envisaged as a novel target in the treatment of cancer.

Structural modeling, in vitro antiproliferative activity, and the effect of substituents on the DNA fastening and scission actions of heteroleptic copper(ii) complexes with terpyridines and naproxen

A new series of heteroleptic copper(ii) complexes with terpyridines and naproxen are reported. The results of biological activity are laying a foundation for the design of new anticancer agents.

Expression of cluster of differentiation-95 and relevant signaling molecules in liver cancer

The present study investigated the protein expression levels of cluster of differentiation (CD)95, caspase‑8, caspase‑3 and poly(ADP‑ribose) polymerase 1 (PARP1) in liver cancer and its association with clinical pathological parameters. The results demonstrated that the expression of CD95 correlated with histological differentiation, liver cirrhosis, lymph node metastasis and distant metastasis (P<0.05), however, no correlations with gender, age, quantity of tumor nodules or T stage were observed (P>0.05). The expression of CD95 was upregulated using a plasmid, which led to an increase in the expression levels of caspase‑8 and caspase‑3 and a decrease in the expression of PARP1. Upregulation of CD95 also promoted the apoptosis of the liver cancer cells. These results indicated that CD95 was associated with liver cancer and promoted the apoptosis of liver cancer cells by caspase‑8, caspase‑3 and PARP1.

Recent advancement in understanding colitis-associated tumorigenesis

Chronic inflammation predisposes patients with inflammatory bowel disease to the risk of developing colitis-associated cancer (CAC). Growing evidence strongly suggests that CAC development is multifactorial and is attributed to concurrent, dynamic dysregulations in host immunity, enteric microbiota, and epithelial restitution during the course of chronic inflammation. This article discusses the recent advances in understanding the different forms of CAC that may develop in patients with inflammatory bowel disease and animal models, as well as molecular alterations and other processes that orchestrate the development of CAC.

Immunological response in Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening cutaneous adverse drug reactions that induce widespread epidermal necrosis. Recent advances in pharmacogenomic studies have provided evidence of genetic predispositions to SJS/TEN. Several concepts have been proposed to explain the pathogenesis of severe cutaneous adverse drug reactions. In the hapten concept, small molecules called haptens elicit an immune response only when attached to proteins. The "p-i" concept postulates that the causative drugs can stimulate cells by binding directly and reversibly to immune receptors. In addition, there is the idea that drugs alter the antigen by binding to the human leukocyte antigen pocket. With regard to keratinocyte death, several cell death mediators, such as FasL, granulysin and annexin A1, have been proposed as playing a role in SJS/TEN pathogenesis. A subset of T lymphocytes, including regulatory T cells, also may play a role in SJS/TEN.

The CD95/CD95L Signaling Pathway: A Role in Carcinogenesis

Apoptosis is a fundamental process contributing to tissue homeostasis, immune response, and development. CD95, also called Fas, is a member of the tumor necrosis factor receptor (TNF-R) superfamily. Its ligand, CD95L, was initially detected at the plasma membrane of activated T lymphocytes and natural killer (NK) cells where it contributes to the elimination of transformed and infected cells. Given its implication in immune homeostasis and immune surveillance combined with the fact that various lineages of malignant cells exhibit loss-of-function mutations, CD95 was initially classified as a tumor suppressor gene. Nonetheless, in different pathophysiological contexts, this receptor is able to transmit non-apoptotic signals and promote inflammation and carcinogenesis. Although the different non-apoptotic signaling pathways (NF-κB, MAPK, and PI3K) triggered by CD95 are known, the initial molecular events leading to these signals, the mechanisms by which the receptor switches from an apoptotic function to an inflammatory role, and, more importantly, the biological functions of these signals remain elusive.

Mechanisms of apoptosis in irradiated and sunitinib-treated follicular thyroid cancer cells

The multikinase inhibitor sunitinib (S) seems to have promising potential in the treatment of thyroid cancer. We focused on the impact of S and/or irradiation (R) on mechanisms of apoptosis in follicular thyroid cancer cells. The effects of R, S and their combination were evaluated 2 and 4 days after treatment, using the human thyroid cancer cell line CGTH W-1. The transcription of genes involved in the regulation of apoptosis was investigated using quantitative real-time PCR. Western blot analyses of caspases and survivin were also performed. S elevated BAX (day 4), CASP9, CASP3, BIRC5 (day 4) and PRKACA (day 4) gene expression, whereas the mRNAs of BCL2, CASP8, PRKCA, ERK1, and ERK2 were not significantly changed. S, R and R+S clearly induced caspase-9 protein and elevated caspase-3 activity. Survivin was down-regulated at day 4 in control cells and the expression was blunted by S treatment. R+S induced survivin expression at day 2 followed by a reduction at day 4 of treatment. Sunitinib and the combined application with radiation induced apoptosis in follicular thyroid cancer cells via the intrinsic pathway of apoptosis. In addition, sunitinib might induce apoptosis via decreased expression of the anti-apoptotic protein survivin. These findings suggest the potential use of sunitinib for the treatment of poorly differentiated follicular thyroid carcinomas.

The CD95/CD95L signaling pathway: a role in carcinogenesis

Apoptosis is a fundamental process that contributes to tissue homeostasis, immune responses, and development. The receptor CD95, also called Fas, is a member of the tumor necrosis factor receptor (TNF-R) superfamily. Its cognate ligand, CD95L, is implicated in immune homeostasis and immune surveillance, and various lineages of malignant cells exhibit loss-of-function mutations in this pathway; therefore, CD95 was initially classified as a tumor suppressor gene. However, more recent data indicate that in different pathophysiological contexts, this receptor can transmit non-apoptotic signals, promote inflammation, and contribute to carcinogenesis. A comparison with the initial molecular events of the TNF-R signaling pathway leading to non-apoptotic, apoptotic, and necrotic pathways reveals that CD95 is probably using different molecular mechanisms to transmit its non-apoptotic signals (NF-κB, MAPK, and PI3K). As discussed in this review, the molecular process by which the receptor switches from an apoptotic function to an inflammatory role is unknown. More importantly, the biological functions of these signals remain elusive.

Differential regulation of inflammation and apoptosis in Fas-resistant hepatocyte-specific Bid-deficient mice

BACKGROUND & AIMS

Activation of Fas death receptor results in apoptosis in multiple organs, particularly liver, in a process dependent on Bid cleavage. Mice injected with an anti-Fas antibody die within hours of acute liver failure associated with massive apoptosis and hemorrhage. Our aim was to investigate the crosstalk of apoptotic and inflammatory pathways and the contribution of selective hepatocellular apoptosis during in vivo Fas activation.

METHODS

We generated hepatocyte-specific Bid deficient mice (hBid(-/-)). Acute liver injury was induced by Fas-activating antibody (Jo2) in a time-course study.

RESULTS

In contrast to controls, nearly all Jo2 injected hBid(-/-) survived. Their livers showed complete protection against hepatocellular apoptosis with minimal focal hemorrhagic changes and mainly non-parenchymal cell apoptosis. In agreement, the hepatocytes had no mitochondrial cytochrome c release in cytosol, or caspase 3 activation. hBid(-/-) livers showed marked increase in acute inflammatory foci composed of neutrophils and monocytes associated with the increased expression of proinflammatory chemokines and cytokines, in the manner dependent on non-canonical interleukin-1β activation and amplified in the absence of caspase-3 activation. In addition, hBid(-/-) mice were completely protected from hepatotoxicity and the infiltrated cells were cleared 2 weeks post single Jo2 injection.

CONCLUSIONS

Hepatocyte Bid suppression is critical for the resistance to the lethal effects of Fas activation in vivo. Fas signaling induces differential activation of non-canonical interleukin-1β maturation, amplified in the absence of apoptotic Bid-mitochondrial loop, in hepatocytes. These findings may have important pathophysiological and therapeutic implications in a variety of liver disorders associated with Fas activation.

Getting TRAIL back on track for cancer therapy

Unlike other members of the TNF superfamily, the TNF-related apoptosis-inducing ligand (TRAIL, also known as Apo2L) possesses the unique capacity to induce apoptosis selectively in cancer cells in vitro and in vivo. This exciting discovery provided the basis for the development of TRAIL-receptor agonists (TRAs), which have demonstrated robust anticancer activity in a number of preclinical studies. Subsequently initiated clinical trials testing TRAs demonstrated, on the one hand, broad tolerability but revealed, on the other, that therapeutic benefit was rather limited. Several factors that are likely to account for TRAs' sobering clinical performance have since been identified. First, because of initial concerns over potential hepatotoxicity, TRAs with relatively weak agonistic activity were selected to enter clinical trials. Second, although TRAIL can induce apoptosis in several cancer cell lines, it has now emerged that many others, and importantly, most primary cancer cells are resistant to TRAIL monotherapy. Third, so far patients enrolled in TRA-employing clinical trials were not selected for likelihood of benefitting from a TRA-comprising therapy on the basis of a valid(ated) biomarker. This review summarizes and discusses the results achieved so far in TRA-employing clinical trials in the light of these three shortcomings. By integrating recent insight on apoptotic and non-apoptotic TRAIL signaling in cancer cells, we propose approaches to introduce novel, revised TRAIL-based therapeutic concepts into the cancer clinic. These include (i) the use of recently developed highly active TRAs, (ii) the addition of efficient, but cancer-cell-selective TRAIL-sensitizing agents to overcome TRAIL resistance and (iii) employing proteomic profiling to uncover resistance mechanisms. We envisage that this shall enable the design of effective TRA-comprising therapeutic concepts for individual cancer patients in the future.

RNA Viruses: ROS-Mediated Cell Death

Reactive oxygen species (ROS) are well known for being both beneficial and deleterious. The main thrust of this review is to investigate the role of ROS in ribonucleic acid (RNA) virus pathogenesis. Much evidences has accumulated over the past decade, suggesting that patients infected with RNA viruses are under chronic oxidative stress. Changes to the body's antioxidant defense system, in relation to SOD, ascorbic acid, selenium, carotenoids, and glutathione, have been reported in various tissues of RNA-virus infected patients. This review focuses on RNA viruses and retroviruses, giving particular attention to the human influenza virus, Hepatitis c virus (HCV), human immunodeficiency virus (HIV), and the aquatic Betanodavirus. Oxidative stress via RNA virus infections can contribute to several aspects of viral disease pathogenesis including apoptosis, loss of immune function, viral replication, inflammatory response, and loss of body weight. We focus on how ROS production is correlated with host cell death. Moreover, ROS may play an important role as a signal molecule in the regulation of viral replication and organelle function, potentially providing new insights in the prevention and treatment of RNA viruses and retrovirus infections.

Hyperthermia Using Antibody-Conjugated Magnetic Nanoparticles and Its Enhanced Effect with Cryptotanshinone

Heat dissipation by magnetic nanoparticles (MNPs) under an alternating magnetic field can be used to selectively treat cancer tissues. Antibodies conjugated to MNPs can enhance the therapeutic effects of hyperthermia by altering antibody-antigen interactions. Fe₃O₄ nanoparticles (primary diameter, 20–30 nm) coated with polyethylenimine (PEI) were prepared and conjugated with CH11, an anti-Fas monoclonal antibody. HeLa cell growth was then evaluated as a function of antibody and MNP/antibody complex doses. HeLa cell growth decreased with increased doses of the antibody and complexes. However, MNPs alone did not affect cell growth; thus, only the antibody affected cell growth. In hyperthermia experiments conducted using an alternating magnetic field frequency of 210 kHz, cell viability varied with the intensity of the applied alternating magnetic field, because the temperature increase of the culture medium with added complexes was dependent on magnetic field intensity. The HeLa cell death rate with added complexes was significantly greater as compared with that with MNPs alone. Cryptotanshinone, an anti-apoptotic factor blocker, was also added to cell cultures, which provided an additional anti-cancer cell effect. Thus, an anti-cancer cell effect using a combination of magnetic hyperthermia, an anti-Fas antibody and cryptotanshinone was established.

Inactivation of the transcription factor GLI1 accelerates pancreatic cancer progression

The role of GLI1 in pancreatic tumor initiation promoting the progression of preneoplastic lesions into tumors is well established. However, its function at later stages of pancreatic carcinogenesis remains poorly understood. To address this issue, we crossed the gli1 knock-out (GKO) animal with cre-dependent pancreatic activation of oncogenic kras concomitant with loss of the tumor suppressor tp53 (KPC). Interestingly, in this model, GLI1 played a tumor-protective function, where survival of GKO/KPC mice was reduced compared with KPC littermates. Both cohorts developed pancreatic cancer without significant histopathological differences in survival studies. However, analysis of mice using ultrasound-based imaging at earlier time points showed increased tumor burden in GKO/KPC mice. These animals have larger tumors, decreased body weight, increased lactate dehydrogenase production, and severe leukopenia. In vivo and in vitro expression studies identified FAS and FAS ligand (FASL) as potential mediators of this phenomenon. The FAS/FASL axis, an apoptotic inducer, plays a role in the progression of pancreatic cancer, where its expression is usually lost or significantly reduced in advanced stages of the disease. Chromatin immunoprecipitation and reporter assays identified FAS and FASL as direct targets of GLI1, whereas GKO/KPC mice showed lower levels of this ligand compared with KPC animals. Finally, decreased levels of apoptosis were detected in tumor tissue in the absence of GLI1 by TUNEL staining. Together, these findings define a novel pathway regulated by GLI1 controlling pancreatic tumor progression and provide a new theoretical framework to help with the design and analysis of trials targeting GLI1-related pathways.

Transplantation of co-aggregates of Sertoli cells and islet cells into liver without immunosuppression

BACKGROUND

Transplantation of islets of Langerhans (islets) was used to treat insulin-dependent diabetes mellitus. However, islet grafts must be maintained by administration of immunosuppressive drugs, which can lead to complications in the long term. An approach that avoids immunosuppressive drug use is desirable.

METHODS

Co-aggregates of Sertoli cells and islet cells from BALB/c mice that were prepared by the hanging drop method were transplanted into C57BL/6 mouse liver through the portal vein as in human clinical islet transplantation.

RESULTS

The core part of the aggregates contained mainly Sertoli cells, and these cells were surrounded by islet cells. The co-aggregates retained the functions of both Sertoli and islet cells. When 800 co-aggregates were transplanted into seven C57BL/6 mice via the portal vein, six of seven recipient mice demonstrated quasi-normoglycemia for more than 100 days.

CONCLUSIONS

The hanging drop method is suitable for preparing aggregates of Sertoli and islet cells for transplantation. Notably, transplantation of these allogeneic co-aggregates into mice with chemically induced diabetes via the portal vein resulted in long-term graft survival without systemic immunosuppression.

Understanding the conservation patterns and molecular phylogenetics of human death receptors family through computational biology

Human death receptors (TNFR1, FAS, DR3, DR4, DR5, DR6 and TNFBR), primarily from tumor necrosis receptor super family, play an essential role in the process of the extrinsic pathway of apoptosis. We performed conserved domain, amino acid residues analysis in which cysteine residues were found to be highly conserved for all the family members. Sixteen (16) highly conserved residues were observed in TNFR1, DR3 and TNFBR; and in case of Fas, only seven (7) residues are highly conserved. From molecular phylogenetics, we found that DR5 and DR4, TNFR1 and DR3 and TNFR1 and DR3 had the same point of origin. Alternatively, Fas was found to be distant from the rest of the death receptors. A network map was developed to explain these proteins are not only interlinked among themselves, but also interlinked with several other proteins. We have also observed from this system that scores of all the nodes ranges from 0.996 to 0.999.

Therapeutic effect of polysaccharide of large yellow croaker swim bladder on lupus nephritis of mice

The therapeutic effect of polysaccharide of large yellow croaker swim bladder (PLYCSB) on lupus nephritis has been studied in vivo. A high concentration (50 mg/kg dose) of PLYCSB reduced the levels of serum inflammatory cytokine levels of IL-6, IL-12, TNF-α and IFN-γ compared to a low concentration (25 mg/kg dose) and control mice. SCr, BUN, TC and TG serum levels of PLYCSB treated mice were lower than those of control mice, and TP and ALB serum levels were higher than control mice. Control mice tested ds-DNA positive at the 6th week, and 50 mg/kg treated mice tested at the 10th week after the experiment began. The output of urine protein of 50 mg/kg PLYCSB treated mice was most closely comparable to the normal mice. The glomerular number of 50 mg/kg PLYCSB treated mice was more than the 25 mg/kg dose and control groups, and the 50 mg/kg dose group showed the lowest glomerular sclerosis index in lupus nephritis mice. By RT-PCR and western blot assay, PLYCSB significantly induced inflammation in kidney tissues of mice by downregulating NF-κB-p65, TGF-β1, Fas, FasL and upregulating IκB-α. These results suggest that PLYCSB showed a potential curative effect on lupus nephritis as a drug or functional food.

FAS-670 gene polymorphism and cervical carcinogenesis risk: A meta-analysis

FAS is a cell surface receptor that plays an important role in the etiology of cancer. Previous studies on the association between FAS-670 polymorphism and cervical carcinogenesis failed to reach a consensus; therefore, this meta-analysis was conducted to estimate the association of FAS-670 polymorphism and the risk of cervical cancer. This meta-analysis included 10 studies on FAS-670 genotyping, including a total of 2,901 cases and 2,831 controls. The complete overdominant model was applied in our meta-analysis [AB vs. AA: odds ratio (OR)=0.879, 95% confidence interval (CI): 0.775-0.998, P=0.046; BB vs. AA: OR=0.903, 95% CI: 0.775-1.052, P=0.190]. The random effects OR was 1.13 (95% CI: 0.95-1.34, I²=52.7%, P_{heterogeneity}=0.03). An ethnic subgroup analysis was subsequently performed. The OR for Asians was 1.25 (6 comparisons, 95% CI: 1.05-1.48, I²=23.5%, P_{heterogeneity}=0.03), whereas for Caucasians, no significant association was observed between FAS-670 polymorphism and cervical carcinogenesis (4 comparisons, OR=0.96, 95% CI: 0.75-1.24, I²=45.9%, P_{heterogeneity}=0.14).

Association of the polymorphisms in the Fas/FasL promoter regions with cancer susceptibility: a systematic review and meta-analysis of 52 studies

Fas and its ligand (FasL) play an important role in apoptosis and carcinogenesis. Therefore, the potential association of polymorphisms in the Fas (-670A>G, rs1800682; -1377G>A, rs2234767) and FasL (-844C>T, rs763110) with cancer risk has been widely investigated. However, all the currently available results are not always consistent. In this work, we performed a meta-analysis to further determine whether carriers of the polymorphisms in Fas and FasL of interest could confer an altered susceptibility to cancer. All relevant data were retrieved by PubMed and Web of Science, and 52 eligible studies were chosen for this meta-analysis. There was no association of the Fas -670A>G polymorphism with cancer risk in the pooled data. For the Fas -1377G>A and FasL -844C>T polymorphisms, results revealed that the homozygotes of -1377A and -844C were associated with elevated risk of cancer as a whole. Further stratified analysis indicated markedly increased risk for developing breast cancer, gastric cancer, and esophageal cancer, in particular in Asian population. We conclude that carriers of the Fas-1377A and the FasL -844C are more susceptible to the majority of cancers than non-carriers.

Clinical utility of urinary soluble Fas in screening for bladder cancer

AIM

Early diagnosis of carcinoma of urinary bladder remains a challenge. Urine cytology, as an adjunct to cystoscopy, is less sensitive for low-grade tumors. Soluble Fas (sFas), a cell-surface receptor and member of the tumor necrosis factor superfamily, is frequently expressed in urinary bladder carcinoma. The objective of this study was to investigate the urinary sFas for diagnosis of transitional cell carcinoma (TCC) of urinary bladder.

METHODS

We examined urinary sFas concentration in 74 controls and 117 cases of TCC, both primary and recurrent disease, by using enzyme-linked immunosorbent assay and compared it with urinary cytology.

RESULT

Urinary sFas concentration was found to be significantly higher in the patient as compared to control group (P < 0.05). An optimal cutoff value of 174.0 pg/mL was proposed. The urinary sFas level was found to have an approximate sensitivity and specificity of 88.03% and 89.19% (P < 0.001), whereas urine cytology had sensitivity of 66.67% and specificity of 95.95%. sFas had better sensitivity in higher grade and both primary and recurrent cases of urinary bladder cancer in comparison with cytology. Out of 15 node positive bladder cancer cases, 13 had high urinary sFas levels, whereas 12 were urinary cytology positive for malignancy.

CONCLUSION

Urinary sFas can be used as a non-invasive diagnostic biomarker for TCC of urinary bladder, both for primary and recurrent disease.

Bcl-2 knockdown accelerates T cell receptor-triggered activation-induced cell death in jurkat T cells

Cell death and survival are tightly controlled through the highly coordinated activation/inhibition of diverse signal transduction pathways to insure normal development and physiology. Imbalance between cell death and survival often leads to autoimmune diseases and cancer. Death receptors sense extracellular signals to induce caspase-mediated apoptosis. Acting upstream of CED-3 family proteases, such as caspase-3, Bcl-2 prevents apoptosis. Using short hairpin RNAs (shRNAs), we suppressed Bcl-2 expression in Jurkat T cells, and this increased TCR-triggered AICD and enhanced TNFR gene expression. Also, knockdown of Bcl-2 in Jurkat T cells suppressed the gene expression of FLIP, TNF receptor-associated factors 3 (TRAF3) and TRAF4. Furthermore, suppressed Bcl-2 expression increased caspase-3 and diminished nuclear factor kappa B (NF-κB) translocation.

Recent progress and new perspectives in lymphoma glycobiology

Glycosylation has recently become one of the most significant subjects in tumor biology, and cell surface glycosylation is closely associated with various biological phenomena in tumor cells. However, the biological significance of cell surface glycosylation and sialic acid linked to glycans in human malignant lymphoma is not well elucidated. We have determined that 1) sialylation or loss of N-glycosylation is closely associated with a worse prognosis in human diffuse large B-cell lymphoma (DLBCL), and 2) glycosylation or sialic acid on the surface of lymphoma cells plays significant roles in cell adhesion or invasion to the extracellular matrix, cell growth, apoptosis and cell death. In the present review, the biological functions of glycosylation or sialic acid in human malignant lymphoma are discussed.

Human cytomegalovirus suppresses Fas expression and function

Human cytomegalovirus (HCMV) is known to evade extrinsic pro-apoptotic pathways not only by downregulating cell surface expression of the death receptors TNFR1, TRAIL receptor 1 (TNFRSF10A) and TRAIL receptor 2 (TNFRSF10B), but also by impeding downstream signalling events. Fas (CD95/APO-1/TNFRSF6) also plays a prominent role in apoptotic clearance of virus-infected cells, so its fate in HCMV-infected cells needs to be addressed. Here, we show that cell surface expression of Fas was suppressed in HCMV-infected fibroblasts from 24 h onwards through the late phase of productive infection, and was dependent on de novo virus-encoded gene expression but not virus DNA replication. Significant levels of the fully glycosylated (endoglycosidase-H-resistant) Fas were retained within HCMV-infected cells throughout the infection within intracellular membranous structures. HCMV infection provided cells with a high level of protection against Fas-mediated apoptosis. Downregulation of Fas was observed with HCMV strains AD169, FIX, Merlin and TB40.

hnRNP A1 contacts exon 5 to promote exon 6 inclusion of apoptotic Fas gene

Fas is a transmembrane cell surface protein recognized by Fas ligand (FasL). When FasL binds to Fas, the target cells undergo apoptosis. A soluble Fas molecule that lacks the transmembrane domain is produced from skipping of exon 6 encoding this region in alternative splicing procedure. The soluble Fas molecule has the opposite function of intact Fas molecule, protecting cells from apoptosis. Here we show that knockdown of hnRNP A1 promotes exon 6 skipping of Fas pre-mRNA, whereas overexpression of hnRNP A1 reduces exon 6 skipping. Based on the bioinformatics approach, we have hypothesized that hnRNP A1 functions through interrupting 5' splice site selection of exon 5 by interacting with its potential binding site close to 5' splice site of exon 5. Consistent with our hypothesis, we demonstrate that mutations of the hnRNP A1 binding site on exon 5 disrupted the effects of hnRNP A1 on exon 6 inclusion. RNA pull-down assay and then western blot analysis with hnRNP A1 antibody prove that hnRNP A1 contacts the potential binding site RNA sequence on exon 5 but not the mutant sequence. In addition, we show that the mutation of 5' splice site on exon 5 to a less conserved sequence destructed the effects of hnRNP A1 on exon 6 inclusion. Therefore we conclude that hnRNP A1 interacts with exon 5 to promote distal exon 6 inclusion of Fas pre-mRNA. Our study reveals a novel alternative splicing mechanism of Fas pre-mRNA.

Spatiotemporal changes in NFATc4 expression of retinal ganglion cells after light-induced damage

Nuclear factor of activated T cells, cytoplasmic 4 (NFATc4) is one of the four members of the NFAT family, which were described first as essential components of T cells activation and lately as important regulators for the initiation and coordination of the immune response, including B cells and natural killer cells. Accumulating evidence has demonstrated that NFATc4 exerted a pro-apoptotic effect in the pathogenesis of various experimental central nervous system diseases by upregulating Fas ligand (FasL) levels. However, the function of NFATc4 in the retina is still with limited acquaintance. To investigate whether NFATc4 is involved in retinal neuron apoptosis, we performed a light-induced retinal damage model in adult rats. A significant upregulation of NFATc4 was detected in the retina after light-induced damage by using Western blotting and reverse transcriptase PCR (RT-PCR). Besides this, NFATc4 was observed to be localized mainly in the retinal ganglion cells (RGCs). In addition, the expression patterns of active caspase-3, active caspase-8, and FasL were parallel with that of NFATc4. We also found the co-localization of NFATc4 with active caspase-3 and FasL in RGCs after light exposure. Collectively, we hypothesized that NFATc4 might participate in RGCs apoptosis by upregulating FasL levels.

Sodium hydrosulfide alleviates lung inflammation and cell apoptosis following resuscitated hemorrhagic shock in rats

AIM

To investigate the protective effects of hydrogen sulfide (H2S) against inflammation, oxidative stress and apoptosis in a rat model of resuscitated hemorrhagic shock.

METHODS

Hemorrhagic shock was induced in adult male SD rats by drawing blood from the femoral artery for 10 min. The mean arterial pressure was maintained at 35-40 mmHg for 1.5 h. After resuscitation the animals were observed for 200 min, and then killed. The lungs were harvested and bronchoalveolar lavage fluid was prepared. The levels of relevant proteins were examined using Western blotting and immunohistochemical analyses. NaHS (28 μmol/kg, ip) was injected before the resuscitation.

RESULTS

Resuscitated hemorrhagic shock induced lung inflammatory responses and significantly increased the levels of inflammatory cytokines IL-6, TNF-α, and HMGB1 in bronchoalveolar lavage fluid. Furthermore, resuscitated hemorrhagic shock caused marked oxidative stress in lung tissue as shown by significant increases in the production of reactive oxygen species H2O2 and ·OH, the translocation of Nrf2, an important regulator of antioxidant expression, into nucleus, and the decrease of thioredoxin 1 expression. Moreover, resuscitated hemorrhagic shock markedly increased the expression of death receptor Fas and Fas-ligand and the number apoptotic cells in lung tissue, as well as the expression of pro-apoptotic proteins FADD, active-caspase 3, active-caspase 8, Bax, and decreased the expression of Bcl-2. Injection with NaHS significantly attenuated these pathophysiological abnormalities induced by the resuscitated hemorrhagic shock.

CONCLUSION

NaHS administration protects rat lungs against inflammatory responses induced by resuscitated hemorrhagic shock via suppressing oxidative stress and the Fas/FasL apoptotic signaling pathway.

Fas gene variants in childhood acute lymphoblastic leukemia and association with prognosis

Fas molecule is one of the main important molecules involved in apoptotic cell death. Single nucleotide polymorphisms in the promoter of Fas gene at positions -1377G/A and -670 A/G may affect its expression and play an important role in the pathology of leukemia. In the present study the association between these polymorphisms and risk of the development of acute lymphoblastic leukemia (ALL) in children with ALL compared to cancer-free control subjects was examined by polymerase chain reaction- based restriction fragment length polymorphism. The relationship between the polymorphisms and clinical and laboratory features of the patients and response to therapy were determined. No significant differences in genotype and allele frequencies between the patients and the control subjects at positions -670 and -1377 were detected. Evaluation of the prognostic factors revealed an association between the GG genotype at position -670 and liver involvement in ALL patients (p < 0.04). Although patients with -1377 AA genotype showed shorter mean complete remission duration, the result of survival analysis did not reach to be significant. In conclusion, results of this study showed no contribution of Fas genotypes at positions -670 and -1377 to risk of ALL in children. The association of Fas GG genotype at position -670 with liver involvement in the patients may show its important role in prognosis of ALL.

Down-regulation of Fas-mediated apoptosis by plasma transglutaminase factor XIII that catalyzes fetal-specific cross-link of the Fas molecule

The Fas antigen, also designated as APO-1 or CD95, is a member of the tumor necrosis factor receptor superfamily and can mediate apoptotic cell death in various cells. We report here that blood coagulation factor XIII (plasma transglutaminase, fibrin stabilizing factor) inhibits apoptosis induced by a cytotoxic anti-Fas monoclonal antibody in Jurkat cells. When cells were treated with the antibody in fetal calf serum-containing media, higher-molecular-weight (180K) polypeptides containing Fas molecule were detected by immunoblotting. Under conditions where the transglutaminase activity was eliminated or suppressed, the cross-link of Fas was not observed, and concurrently cell death was hastened. Moreover, an antibody against factor XIII strongly accelerated the Fas-mediated apoptosis. Furthermore, addition of partially purified factor XIII neutralized the apoptosis-promoting effect of anti-factor XIII antibody, indicating that this enzyme is involved in cross-link of Fas and down-regulates Fas-mediated apoptotic cell death. Significantly, the cross-link of Fas was seen only in fetal calf serum but not in newly-born calf serum, 1-year-old calf serum or adult bovine serum. These data suggest that plasma transglutaminase factor XIII may play a key role in fetal development of vertebrates via cross-link of Fas antigen.

Electronegative LDL: a circulating modified LDL with a role in inflammation

Electronegative low density lipoprotein (LDL(−)) is a minor modified fraction of LDL found in blood. It comprises a heterogeneous population of LDL particles modified by various mechanisms sharing as a common feature increased electronegativity. Modification by oxidation is one of these mechanisms. LDL(−) has inflammatory properties similar to those of oxidized LDL (oxLDL), such as inflammatory cytokine release in leukocytes and endothelial cells. However, in contrast with oxLDL, LDL(−) also has some anti-inflammatory effects on cultured cells. The inflammatory and anti-inflammatory properties ascribed to LDL(−) suggest that it could have a dual biological effect.

Antiapoptotic Effects of EGb 761

Ginkgo biloba extracts have long been used in Chinese traditional medicine for hundreds of years. The most significant extract obtained from Ginkgo biloba leaves has been EGb 761, a widely used phytopharmaceutical product in Europe. EGb 761 is a well-defined mixture of active compounds, which contains two main active substances: flavonoid glycosides (24-26%) and terpene lactones (6-8%). These compounds have shown antiapoptotic effects through the protection of mitochondrial membrane integrity, inhibition of mitochondrial cytochrome c release, enhancement of antiapoptotic protein transcription, and reduction of caspase transcription and DNA fragmentation. Other effects include the reduction of oxidative stress (which has been related to the occurrence of vascular, degenerative, and proliferative diseases), coupled to strong induction of phase II-detoxifying and cellular defense enzymes by Nrf2/ARE activation, in addition to the modulation of transcription factors, such as CREB, HIF-1 α , NF- κ B, AP-1, and p53, involved in the apoptosis process. This work reviews experimental results about the antiapoptotic effects induced by the standardized extract of Ginkgo biloba leaves (EGb 761).

Structural and biophysical characterization of the interactions between the death domain of Fas receptor and calmodulin

The extrinsic apoptotic pathway is initiated by cell surface death receptors such as Fas. Engagement of Fas by Fas ligand triggers a conformational change that allows Fas to interact with adaptor protein Fas-associated death domain (FADD) via the death domain, which recruits downstream signaling proteins to form the death-inducing signaling complex (DISC). Previous studies have shown that calmodulin (CaM) is recruited into the DISC in cholangiocarcinoma cells, suggesting a novel role of CaM in Fas-mediated signaling. CaM antagonists induce apoptosis through a Fas-related mechanism in cholangiocarcinoma and other cancer cell lines possibly by inhibiting Fas-CaM interactions. The structural determinants of Fas-CaM interaction and the underlying molecular mechanisms of inhibition, however, are unknown. Here we employed NMR and biophysical techniques to elucidate these mechanisms. Our data show that CaM binds to the death domain of Fas (FasDD) with an apparent dissociation constant (Kd) of ~2 μM and 2:1 CaM:FasDD stoichiometry. The interactions between FasDD and CaM are endothermic and entropically driven, suggesting that hydrophobic contacts are critical for binding. We also show that both the N- and C-terminal lobes of CaM are important for binding. NMR and surface plasmon resonance data show that three CaM antagonists (N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide, tamoxifen, and trifluoperazine) greatly inhibit Fas-CaM interactions by blocking the Fas-binding site on CaM. Our findings provide the first structural evidence for Fas-CaM interactions and mechanism of inhibition and provide new insight into the molecular basis for a novel role of CaM in regulating Fas-mediated apoptosis.

Fas/Fas ligand-mediated apoptosis in different cell lineages and functional compartments of human lymph nodes

We have optimized an immunohistochemical double-staining method combining immunohistochemical lymphocyte lineage marker detection and apoptosis detection with terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling. The method was used to trace Fas-mediated apoptosis in human reactive lymph nodes according to cell lineage and anatomical location. In addition to Fas, we also studied the expression of Fas ligand (FasL), CD3, CD20, CD19, CD23, and CD68 of apoptotic cells. The presence of simultaneous Fas and FasL positivity indicated involvement of activation-induced death in the induction of paracortical apoptosis. FasL expression in the high endothelial venules might be an inductor of apoptosis of Fas-positive lymphoid cells. In addition to B-lymphocyte apoptosis in the germinal centers, there was often a high apoptosis rate of CD23-expressing follicular dendritic cells. In summary, our double-staining method provides valuable new information about the occurrence and mechanisms of apoptosis of different immune cell types in the lymph node compartments. Among other things, we present support for the importance of Fas/FasL-mediated apoptosis in lymph node homeostasis.

Cellular-FLIP, Raji isoform (c-FLIP R) modulates cell death induction upon T-cell activation and infection

Dysregulation of apoptosis caused by an imbalance of pro- and anti-apoptotic protein expression can lead to cancer, neurodegenerative, and autoimmune diseases. Cellular-FLIP (c-FLIP) proteins inhibit apoptosis directly at the death-inducing signaling complex of death receptors, such as CD95, and have been linked to apoptosis regulation during immune responses. While the isoforms c-FLIPL and c-FLIPS are well characterized, the function of c-FLIPR remains poorly understood. Here, we demonstrate the induction of endogenous murine c-FLIPR in activated lymphocytes for the first time. To analyze c-FLIPR function in vivo, we generated transgenic mice expressing murine c-FLIPR specifically in hematopoietic cells. As expected, lymphocytes from c-FLIPR transgenic mice were protected against CD95-induced apoptosis in vitro. In the steady state, transgenic mice had normal cell numbers and unaltered frequencies of B cells and T-cell subsets in lymphoid organs. However, when challenged with Listeria monocytogenes, c-FLIPR transgenic mice showed less liver necrosis and better bacterial clearance compared with infected wild-type mice. We conclude that c-FLIPR expression in hematopoietic cells supports an efficient immune response against bacterial infections.

Death receptor-ligand systems in cancer, cell death, and inflammation

The discovery of tumor necrosis factor (TNF) marked the beginning of one of the most fascinating journeys in modern biomedical research. For the moment, this journey has culminated in the development of drugs that inhibit TNF. TNF blockers have revolutionized the treatment of many chronic inflammatory diseases. Yet, the journey seems far from over. TNF is the founding member of a family of cytokines with crucial functions in cell death, inflammation, and cancer. Some of these factors, most prominently TNF, CD95L, and TRAIL, can induce cell death. The receptors that mediate this signal are therefore referred to as death receptors, even though they also activate other signals. Here I will take you on a journey into the discovery and study of death receptor-ligand systems and how this inspired new concepts in cancer therapy and our current understanding of the interplay between cell death and inflammation.

Functional polymorphisms in cell death pathway genes FAS and FAS ligand and risk of alopecia areata

FAS and FAS ligand (FASLG) are important proapoptotic proteins that have a significant function in regulating cell growth and apoptosis and play essential roles in many human autoimmune diseases. Alopecia areata (AA) is hypothesized to be an organ-specific autoimmune disease mediated by T cells to the hair follicles. The concept of an autoimmune mechanism as the basis for AA led us to investigate a possible association between the FAS and FASLG polymorphism with AA susceptibility and disease progression on AA patients in Turkish population. The study group consisted of 118 unrelated patients with AA and 118 unrelated healthy controls. We genotyped FAS-670 A/G and FASLG-124 A/G polymorphisms and assessed their association with AA risk. A statistically significant difference was observed between patients and controls according to genotype frequencies of FAS gene (p = 0.0002). GG genotype of 670 A/G polymorphism was found to be protective against AA (p = 0.000, OR 0.07, 95 % CI 0.00-0.41). It can be concluded there is a reduced risk of AA risk appeared to be associated with FAS-670 A/G. No association was observed between AA patients and controls according to genotype and allele distribution of FASLG gene 124 A/G polymorphism (p = 0.1297, p = 453, respectively). In conclusion, we provide evidence that FAS/FASLG polymorphisms may have an effect on the risk of AA in the Turkish population. These findings provide an additional support to a genetic basis for AA development.

Expression of Th17-related genes in PHA/IL-2-activated human T cells by Fas signaling via caspase-1- and Stat3-dependent pathway

T helper 17 (Th17) cells, which produce interleukin 17 (IL-17), are involved in the pathogenesis of autoimmune diseases and inflammatory conditions. Th17 cells have been detected in many Fas ligand-positive tumors. This study investigates the expression of Th17-related genes in PHA/IL-2-activated human T cells upon Fas ligation. Activated T cells transiently express RORγt, IL-17A, and IL-17F. A subsequent Fas receptor stimulation or contact with FasL-expressing glioma cells significantly prolongs the induction of RORγt and Th17-related cytokines. Treatments with inhibitors of caspase-1 and Stat3 reduce the Fas-signal-associated induction of RORγt, IL-17A, and IL-17F, as well as the phosphorylation of Stat3. Although the ligation of Fas results in caspase-8 cleavage and ERK1/2 phosphorylation, inhibitors for caspase-8 and MEK have no effect on the expressions of RORγt, IL-17A, and IL-17F. The results suggest that the Fas signal favors the Th17-phenotypic features of human T cells through the caspase-1/Stat3 signaling pathway.