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

CD95/Fas, Non-Apoptotic Signaling Pathways, and Kinases

Endothelial cells lining new blood vessels that develop during inflammatory disorders or cancers act as doors that either allow or block access to the tumor or inflamed organ. Recent data show that these endothelial cells in cancer tissues and inflamed tissues of lupus patients overexpress CD95L, the biological role of which is a subject of debate. The receptor CD95 (also named Fas or apoptosis antigen 1) belongs to the tumor necrosis factor (TNF) receptor superfamily. Its cognate ligand, CD95L, is implicated in immune homeostasis and immune surveillance. Because mutations of this receptor or its ligand lead to autoimmune disorders such as systemic lupus erythematosus (SLE) and cancers, CD95 and CD95L were initially thought to play a role in immune homeostasis and tumor elimination via apoptotic signaling pathways. However, recent data reveal that CD95 also evokes non-apoptotic signals, promotes inflammation, and contributes to carcinogenesis; therefore, it is difficult to dissect its apoptotic effects from its non-apoptotic effects during pathogenesis of disease. CD95L is cleaved by metalloproteases and so exists in two different forms: a transmembrane form and a soluble ligand (s-CD95L). We recently observed that the soluble ligand is overexpressed in serum from patients with triple-negative breast cancer or SLE, in whom it contributes to disease severity by activating non-apoptotic signaling pathways and promoting either metastatic dissemination or accumulation of certain T cell subsets in damaged organs. Here, we discuss the roles of CD95 in modulating immune functions via induction of mainly non-apoptotic signaling pathways.

A study on the expression of apoptotic molecules related to death receptor and endoplasmic reticulum pathways in the jejunum of AFB1-intoxicated chickens

Aflatoxin B₁ (AFB₁) is a common contaminant of poultry feeds in tropical and subtropical climates. Early researches have well established the hepatotoxic, carcinogenic, and immunotoxic effects of AFB₁ on humans and animals. Recently, it has been shown that AFB₁ could cause the up- or down-alteration of mitochondrial pathway molecule expression. However, the information on the expression of death receptor and endoplasmic reticulum molecules in the jejunal apoptosis induced by AFB₁ were unavailable. So the present study was conducted to explore the expression of apoptotic molecules related to death receptor and endoplasmic reticulum in the jejunal cells of chickens exposed to AFB₁ diet for 3 weeks. Total of 144 one-day-old chickens was randomly divided into two groups, namely control group (containing 0 mg/kg AFB₁) and AFB₁ group (containing 0.6 mg/kg AFB₁). Histopathological observation and microscopic quantitative analysis revealed morphological changes in the jejunum such as the shedding of the mucosal epithelial cells in the apical region of villi along with the decrease of villus height, villus area and villus/crypt ratio in the AFB₁ group. Both TUNEL and flow cytometry assays showed that AFB₁ intake induced excessive apoptosis of jejunal cells. Quantitative real-time PCR test displayed the general upregulation of death receptors (FAS, FASL, TNF-α and TNF-R1), endoplasmic reticulum signals (GRP78 and GRP94) as well as initiator and executioner caspases (CASPASE-10, CASPASE-8 and CASPASE-3) in the jejunum of AFB₁-intoxicated chickens. It's the first study demonstrating that AFB₁ induced apoptosis of chickens’ jejunum accompanied by the alteration of death receptor and endoplasmic reticulum molecule expression.

Fas and Fas ligand gene polymorphisms in Turkish patients with Familial Mediterranean Fever

Familial Mediterranean Fever (FMF) is an autosomal recessive autoinflammatory disorder characterized by recurrent fever, serositis, abdominal pain, arthritis, arthralgia and erysipelas like erythema. Fas and Fas ligand molecules play a central role in the apoptosis signaling of various cell types including neutrophils. Neutrophils are the major cell population involved in acute inflammation in patients with FMF and the role of Fas and Fas ligand molecules in this cells of FMF patients may be crucial. Therefore, in the present study, we aimed to investigate whether the Fas cell surface receptor gene (FAS); NM_000043.5: c.-671A>G (rs1800682, MvaI) and Fas ligand gene (FASLG), NM_000639.2: c.-844C>T (rs763110, BsrD1) functional polymorphisms in patients with FMF and their relation to the main clinical features of the disease. The polymorphisms in the promoter regions of FAS c.-671A>G and FASLG c.-844C>T were investigated in 97 non-related FMF patients and 70 non-related healthy controls by using PCR-RFLP technique. The frequencies of FAS c-671AG genotype and G allele were not significantly different between FMF patients and healthy subjects. The frequency of FASLG -844TC genotype was found significantly different between the patients with FMF and healthy controls whereas T or C allele frequency was not significantly different between the groups. Haplotype frequencies of the studied polymorphisms were also not significantly different between FMF patients and controls. There were no correlations between the studied FAS c.-671A>G and FASLG c.-844C>T polymorphisms and the main clinical features of FMF such as fever, arthritis, abdominal and chest pain, arthralgia and erysipelas-like erythema. Our findings suggest that FAS c.-671AG genotype or G allele and FASLG c.-844 allele are not to be a risk factor, whereas FASLG c.-844TC genotype may be protective in the studied Turkish population. According to our results we may suggest that although not statistically significant, higher frequencies of FASLG c.-844CC genotype in FMF patients may be related to delayed apoptosis of neutrophils and ultimately cause neutrophilic inflammation by increasing FASLG expression.

Inhibition of Apoptosis by Expression of Antiapoptotic Proteins in Recombinant Human Keratinocytes

The Fas ligand/Fas interaction plays an important role in the regulation of immune responses. Allografted cells undergo Fas-mediated apoptosis induced by CD8+ T cells. Our objective was to prevent human keratinocytes from immunologically induced apoptosis. We focused on three proteins with inhibitory function on Fas-mediated apoptosis. Human keratinocytes were transfected with either Flip, Faim, or Lifeguard (LFG). The treatment proved to be practicable and efficient. The recombinant keratinocytes with expression of our target proteins were cocultured with CD8+ T cells and the apoptotic activity was then evaluated. Activation of caspase-8 was detectable in control but not in the recombinant cells. Quantitative analysis revealed significant induction of T-cell-induced apoptosis in nontransfected keratinocytes (p = 0.04, n = 12) but not in Flip (p = 0.66), Faim (p = 0.42), or LFG (p = 0.44) expressing cells. Our results suggest that heterotopic expression of antiapoptotic proteins can induce the resistance of keratinocytes to a major mechanism of rejection.

Exploring the TRAILs less travelled: TRAIL in cancer biology and therapy

The discovery that the tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce apoptosis of cancer cells without causing toxicity in mice has led to the in-depth study of pro-apoptotic TRAIL receptor (TRAIL-R) signalling and the development of biotherapeutic drug candidates that activate TRAIL-Rs. The outcome of clinical trials with these TRAIL-R agonists has, however, been disappointing so far. Recent evidence indicates that many cancers, in addition to being TRAIL resistant, use the endogenous TRAIL-TRAIL-R system to their own advantage. However, novel insight on two fronts - how resistance of cancer cells to TRAIL-based pro-apoptotic therapies might be overcome, and how the pro-tumorigenic effects of endogenous TRAIL might be countered - gives reasonable hope that the TRAIL system can be harnessed to treat cancer. In this Review we assess the status quo of our understanding of the biology of the TRAIL-TRAIL-R system - as well as the gaps therein - and discuss the opportunities and challenges in effectively targeting this pathway.

Potential Toxicity of Polymyxins in Human Lung Epithelial Cells

Inhaled polymyxins are of considerable utility in achieving optimal exposure in the respiratory tract for the treatment of lung infections caused by multidrug-resistant Gram-negative pathogens. Current inhaled polymyxin therapy is empirical, and often large doses are used that may lead to potential pulmonary adverse effects. This study aimed to investigate the effect of polymyxins on human lung epithelial (A549) cells. The viability of A549 cells was examined after treatment with polymyxins by flow cytometry. Activation of caspases 3, 8, and 9, expression of Fas ligand (FasL), loss of mitochondrial membrane potential, and mitochondrial oxidative stress induced by polymyxin B were evaluated. The concentration of polymyxin B required to induce 50% of maximal cell death was 1.74 mM (95% confidence interval, 1.60 to 1.90 mM). Colistin was at least 2-fold less toxic than polymyxin B, while colistimethate was nontoxic. With 2.0 mM polymyxin B, 30.6% ± 11.5% (mean ± standard deviation) of the cells were apoptotic at 8 h and this increased to 71.3% ± 3.72% at 24 h. Concentration- and time-dependent activation of caspases 3, 8, and 9 was evident, while the activation of caspase 9 was more dramatic. Furthermore, polymyxin B caused concentration- and time-dependent FasL expression, production of mitochondrial reactive oxygen species, and changes in mitochondrial membrane potential. This is the first study to demonstrate that both extrinsic death receptor and intrinsic mitochondrial pathways are involved in polymyxin-induced toxicity in A549 cells. This knowledge base is critical for the development of novel strategies for the safe and effective inhalation therapy of polymyxins against Gram-negative "superbugs."

Use of Lentiviral Particles As a Cell Membrane-Based mFasL Delivery System for In Vivo Treatment of Inflammatory Arthritis

During budding, lentiviral particles (LVP) incorporate cell membrane proteins in the viral envelope. We explored the possibility of harnessing this process to generate LVP-expressing membrane proteins of therapeutic interest and studied the potential of these tools to treat different pathologies. Fas-mediated apoptosis is central to the maintenance of T cell homeostasis and prevention of autoimmune processes. We prepared LVP that express murine FasL on their surface. Our data indicate that mFasL-bearing LVP induce caspase 3 and 9 processing, cytochrome C release, and significantly more cell death than control LVP in vitro. This cytotoxicity is blocked by the caspase inhibitor Z-VAD. Analysis of the application of these reagents for the treatment of inflammatory arthritis in vivo suggests that FasL-expressing LVP could be useful for therapy in autoimmune diseases such as rheumatoid arthritis, where there is an excess of Fas-expressing activated T cells in the joint. LVP could be a vehicle not only for mFasL but also for other membrane-bound proteins that maintain their native conformation and might mediate biological activities.

Short-Term Subclinical Zinc Deficiency in Weaned Piglets Affects Cardiac Redox Metabolism and Zinc Concentration

Background: Subclinical zinc deficiency (SZD) represents the common zinc malnutrition phenotype. However, its association with oxidative stress is not well understood. The heart muscle may be a promising target for studying early changes in redox metabolism.Objective: We investigated the effects of short-term SZD on cardiac redox metabolism in weaned piglets.Methods: Forty-eight weaned German Large White × Landrace × Piétrain piglets (50% castrated males and 50% females; body weight of 8.5 kg) were fed diets with different zinc concentrations for 8 d. Measurements included cardiac parameters of antioxidative capacity, stress-associated gene expression, and tissue zinc status. Analyses comprised (linear, broken-line) regression models and Pearson correlation coefficients.Results: Glutathione and α-tocopherol concentrations as well as catalase, glutathione reductase, B-cell lymphoma 2-associated X protein, and caspase 9 gene expression plateaued in response to reduction in dietary zinc from 88.0 to 57.6, 36.0, 36.5, 41.3, 55.3, and 33.8 mg/kg, respectively (P < 0.0001). Further reduction in dietary zinc promoted a linear decrease of glutathione and α-tocopherol (30 and 0.6 nmol/mg dietary Zn, respectively; P < 0.05) and a linear increase of gene expression [0.02, 0.01, 0.003, and 0.02 Log₁₀(2^-ΔΔCt)/mg dietary Zn, respectively; P < 0.05)]. Tissue zinc declined linearly with reduction in dietary zinc (0.21 mg tissue Zn/mg dietary Zn; P = 0.004) from 88.0 to 42.7 mg/kg (P < 0.0001), below which it linearly increased inversely to further reduction in dietary zinc (0.57 mg tissue Zn/mg dietary Zn; P = 0.006). H₂O₂-detoxification activity and metallothionein 1A gene expression decreased linearly with reduction in dietary zinc from 88.0 to 28.1 mg/kg [0.02 mU and 0.008 Log₁₀(2^-ΔΔCt)/mg dietary Zn, respectively; P < 0.05]. Fas cell-surface death receptor, etoposide-induced 2.4 and cyclin-dependent kinase inhibitor 1A gene expression correlated positively to cardiac zinc in piglets fed ≤42.7 mg Zn/kg (r ≥ 0.97; P < 0.05).Conclusions: Short-term SZD decreased cardiac antioxidative capacity of weaned piglets while simultaneously increasing stress-associated gene expression and zinc concentration. This is the first report to our knowledge on the effects of SZD on redox metabolism.

Daxx plays a novel role in T cell survival but is dispensable in Fas-induced apoptosis

Daxx was originally isolated as a Fas-binding protein. However, the in vivo function of Daxx in Fas-induced apoptosis has remained enigmatic. Fas plays an important role in homeostasis in the immune system. Fas gene mutations lead to autoimmune-lymphoproliferation (lpr) diseases characterized by hyperplasia of secondary lymphoid organs. It is well established that the FADD adaptor binds to Fas, and recruits/activates caspase 8. However, additional proteins including Daxx have also been indicated to associate with Fas. It was proposed that Daxx mediates a parallel apoptotic pathway that is independent of FADD and caspase 8, but signals through ASK1-mediated apoptotic pathway. However, because the deletion of Daxx leads to embryonic lethality, the in vivo function of Daxx has not been properly analyzed. In the current study, analysis was performed using a conditional mutant mouse in which Daxx was deleted specifically in T cells. The data show that Daxx^-/- T cells were able to undergo normal Fas-induced apoptosis. While containing normal thymocyte populations, the T cell-specific Daxx^-/- mice have a reduced peripheral T cell pool. Importantly, Daxx-deficient T cells displayed increased death responses upon activation through TCR stimulation. These results unequivocally demonstrated that Daxx does not mediate Fas-induced apoptosis, but rather that it plays a critical role in survival responses in primary mature T cells.

Programmed cell death and the immune system

More than 50 years ago, cells were observed to die during insect development via a process that was named 'programmed cell death'. Later, a similar cell death process was found to occur in humans, and the process was renamed 'apoptosis'. In the 1990s, a number of apoptosis-regulating molecules were identified, and apoptosis was found to have essential roles in the immune system. In this Timeline article, we highlight the key events that have demonstrated the importance of programmed cell death processes, including apoptosis and programmed necrosis, in the immune system.

Sketching of CD95 Oligomers by In Silico Investigations

This work aimed at building a 3D model of trimeric apo CD95. By combining different molecular modeling approaches and experimental information, we have been able to obtain a consensual organization of the complex. Our strategy permitted the construction of a plausible trimer, and to sketch the interface between protomers. The final model will guide further experimental investigations and understanding of CD95 structure and functions.

FAS and FASL genetic polymorphisms impact on clinical outcome of malignant pleural mesothelioma

Background

FAS-670 A>G (rs1800682) and FASL-844 C>T (rs763110) polymorphisms have been previously correlated with clinical outcome of non-small cell lung cancer (NSCLC) and breast and bladder cancers. We investigated the influence of these polymorphisms on clinical outcome of malignant pleural mesothelioma (MPM) patients.

Patients and methods

In this cohort study (NCT02269878), 68 epithelioid MPM Egyptian patients treated with first-line platinum-based chemotherapy were recruited in the period between April 2014 and May 2015. The genotype analysis was performed using TaqMan^® single-nucleotide polymorphism genotyping assay. The association between the selected polymorphisms and response rate, progression-free survival (PFS) and overall survival (OS) at 18 months was evaluated.

Results

The median age of patients was 55 years and 45.6% of them received platinum in combination with pemetrexed, while 54.4% received platinum in combination with gemcitabine. FASL-844 CC genotype was more common than expected in early-stage tumor (P=0.042). It was found that there was no association between the investigated polymorphisms and response rate or 18-month OS. However, the PFS rate at 18 months for FASL-844 CC genotype carriers was 45% versus 10.6% for FASL-844 CT/TT genotypes carriers (log-rank: 6.2; P=0.013). Also, the number of platinum-based cycles and tumor stage were found to be significant variables for PFS by univariate analysis (P≤0.001 and P=0.006, respectively). Stratified Cox regression showed that the carriers of FASL-844 CT/TT genotypes were still more susceptible to disease progression than carriers of FASL-844 CC genotype (adjusted HR =3.77, 95% CI: 1.34–10.62, P=0.012).

Conclusion

The results of this study suggest that FASL-844 C/T polymorphism could predict PFS in MPM patients receiving platinum-based chemotherapy; therefore, this should be further evaluated as a potential marker for the prediction of clinical outcome in patients with MPM.

A novel transgenic mouse model of lysosomal storage disorder

Knockout technology has proven useful for delineating functional roles of specific genes. Here we describe and provide an explanation for striking pathology that occurs in a subset of genetically engineered mice expressing a rat Ca_Vβ2a transgene under control of the cardiac α-myosin heavy chain promoter. Lesions were limited to mice homozygous for transgene and independent of native Cacnb2 genomic copy number. Gross findings included an atrophied pancreas; decreased adipose tissue; thickened, orange intestines; and enlarged liver, spleen, and abdominal lymph nodes. Immune cell infiltration and cell engulfment by macrophages were associated with loss of pancreatic acinar cells. Foamy macrophages diffusely infiltrated the small intestine's lamina propria, while similar macrophage aggregates packed liver and splenic red pulp sinusoids. Periodic acid-Schiff-positive, diastase-resistant, iron-negative, Oil Red O-positive, and autofluorescent cytoplasm was indicative of a lipid storage disorder. Electron microscopic analysis revealed liver sinusoids distended by clusters of macrophages containing intracellular myelin "swirls" and hepatocytes with enlarged lysosomes. Additionally, build up of cholesterol, cholesterol esters, and triglycerides, along with changes in liver metabolic enzyme levels, were consistent with a lipid processing defect. Because of this complex pathology, we examined the transgene insertion site. Multiple transgene copies inserted into chromosome 19; at this same site, an approximate 180,000 base pair deletion occurred, ablating cholesterol 25-hydroxylase and partially deleting lysosomal acid lipase and CD95 Loss of gene function can account for the altered lipid processing, along with hypertrophy of the immune system, which define this phenotype, and serendipitously provides a novel mouse model of lysosomal storage disorder.

A Pair of Identical Twins Discordant for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Differ in Physiological Parameters and Gut Microbiome Composition

BACKGROUND Patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) present with profound fatigue, flu-like symptoms, pain, cognitive impairment, orthostatic intolerance, and post-exertional malaise (PEM), and exacerbation of some or all of the baseline symptoms. CASE REPORT We report on a pair of 34-year-old monozygotic twins discordant for ME/CFS, with WELL, the non-affected twin, and ILL, the affected twin. Both twins performed a two-day cardiopulmonary exercise test (CPET), pre- and post-exercise blood samples were drawn, and both provided stool samples for biochemical and molecular analysis. At peak exertion for both CPETs, ILL presented lower VO2peak and peak workload compared to WELL. WELL demonstrated normal reproducibility of VO2@ventilatory/anaerobic threshold (VAT) during  CPET2, whereas ILL experienced an abnormal reduction of 13% in VAT during  CPET2. A normal rise in lactate dehydrogenase (LDH), creatine kinase (CK), adrenocorticotropic hormone (ACTH), cortisol, creatinine, and ferritin content was observed following exercise for both WELL and ILL at each CPET. ILL showed higher increases of resistin, soluble CD40 ligand (sCD40L), and soluble Fas ligand (sFasL) after exercise compared to WELL. The gut bacterial microbiome and virome were examined and revealed a lower microbial diversity in ILL compared to WELL, with fewer beneficial bacteria such as Faecalibacterium and Bifidobacterium, and an expansion of bacteriophages belonging to the tailed dsDNA Caudovirales order.  CONCLUSIONS Results suggest dysfunctional immune activation in ILL following exercise and that prokaryotic viruses may contribute to mucosal inflammation and bacterial dysbiosis. Therefore, a two-day CPET and molecular analysis of blood and microbiomes could provide valuable information about ME/CFS, particularly if applied to a larger cohort of monozygotic twins.

Regulation of the miRNA expression by TEL/AML1, BCR/ABL, MLL/AF4 and TCF3/PBX1 oncoproteins in acute lymphoblastic leukemia (Review)

MicroRNAs (miRNAs) are a class of small endogenous non-coding RNAs that play important regulatory roles by targeting mRNAs for cleavage or translational repression. miRNAs act in diverse biological processes including development, cell growth, apoptosis, and hematopoiesis. The miRNA expression is associated with specific cytogenetic changes and can also be used to discriminate between the different subtypes of leukemia in acute lymphoblastic leukemia with common translocations, it is shown that the miRNAs have the potential to be used for clinical diagnosis and prognosis. We reviewed the roles of miRNA here with emphasis on their function in human leukemia and the mechanisms of the TEL/AML1, BCR/ABL, MLL/AF4 and TCF3/PBX1 oncoproteins on miRNAs expression in acute lymphoblastic leukemia.

Mathematical model of tumor-immune surveillance

We present a novel mathematical model involving various immune cell populations and tumor cell populations. The model describes how tumor cells evolve and survive the brief encounter with the immune system mediated by natural killer (NK) cells and the activated CD8(+) cytotoxic T lymphocytes (CTLs). The model is composed of ordinary differential equations describing the interactions between these important immune lymphocytes and various tumor cell populations. Based on up-to-date knowledge of immune evasion and rational considerations, the model is designed to illustrate how tumors evade both arms of host immunity (i.e. innate and adaptive immunity). The model predicts that (a) an influx of an external source of NK cells might play a crucial role in enhancing NK-cell immune surveillance; (b) the host immune system alone is not fully effective against progression of tumor cells; (c) the development of immunoresistance by tumor cells is inevitable in tumor immune surveillance. Our model also supports the importance of infiltrating NK cells in tumor immune surveillance, which can be enhanced by NK cell-based immunotherapeutic approaches.

CD95 maintains stem cell-like and non-classical EMT programs in primary human glioblastoma cells

Glioblastoma (GBM) is one of the most aggressive types of cancer with limited therapeutic options and unfavorable prognosis. Stemness and non-classical epithelial-to-mesenchymal transition (ncEMT) features underlie the switch from normal to neoplastic states as well as resistance of tumor clones to current therapies. Therefore, identification of ligand/receptor systems maintaining this privileged state is needed to devise efficient cancer therapies. In this study, we show that the expression of CD95 associates with stemness and EMT features in GBM tumors and cells and serves as a prognostic biomarker. CD95 expression increases in tumors and with tumor relapse as compared with non-tumor tissue. Recruitment of the activating PI3K subunit, p85, to CD95 death domain is required for maintenance of EMT-related transcripts. A combination of the current GBM therapy, temozolomide, with a CD95 inhibitor dramatically abrogates tumor sphere formation. This study molecularly dissects the role of CD95 in GBM cells and contributes the rational for CD95 inhibition as a GBM therapy.

Quantitative assessment of the association between Fas/FasL gene polymorphism and susceptibility to esophageal carcinoma in a north Chinese population

The case–control study aims to investigate the association of Fas and FasL genetic polymorphisms (Fas‐670A/G (rs1800682), Fas‐1377G/A (rs2234767) and FasL‐844T/C (rs763110)) with esophageal carcinoma susceptibility in a north Chinese population. A total of 204 patients with esophageal carcinoma and 248 healthy controls were enrolled from Henan, China and genotyped by the polymerase chain reaction and restriction fragment length polymorphism method. There were no significant differences in distributions of their genotypes frequencies between patients and controls in Fas‐670A/G, Fas‐1377G/A and FasL‐844T/C polymorphisms (P > 0.05). Stratified analysis showed that no significant association was found between esophageal carcinoma and gene polymorphisms of Fas‐670 A/G, Fas‐1377G/A, and FasL‐844T/C (P > 0.05). Genetic polymorphisms in the death pathway genes Fas and FasL were not associated with risk of developing esophageal carcinoma in a north Chinese population.

Apoptotic Cell Death Induced by ofLBP6A, Lipopolysaccharide Binding Protein Model Peptide, Derived from Paralichthy olivaceus on MKN-28 Cells

The aim of this study was to evaluate the anti-cancer effects of lipopolysaccharide binding protein (LBP) analogs derived from the marine resource Paralichthy olivaceus on MKN-28 gastric cancer cells. Five LBP analogs were used: ofLBP1N, ofLBP2A, ofLBP4N, ofLBP5A, and ofLBP6A. ofLBP6A induced cell death of MKN-28 cells at a concentration of 40 μM. While the anti-proliferation effects ofLBP6A showed on MKN-28 cells at concentration of 40 μM, it did not affect non-cancerous HEK-293 cells at the same concentration. The mechanism study showed that ofLBP6A lead to the inhibition of cell proliferation by apoptosis along with morphological changes. The phosphorylation of Fas associated death domain (FADD) as well as the expressions of cleaved caspase-8, -7, and -3 were increased by ofLBP6A treatment. Increased the expression level of cleaved caspase-3 was confirmed by immunofluorescence staining. The expressions of Bid, Bax, and cytochrome C were also increased by the treatment. However, the expressions of cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein (FLIP), Bcl-XL, and Bcl-2 were decreased by ofLBP6A treatment. The results of this study were the first to demonstrate the apoptotic anti-cancer effects of ofLBP6A, derived from P. olivavaceus on gastric cancer cells.

Cytotoxic L-amino-acid oxidases from Amanita phalloides and Clitocybe geotropa induce caspase-dependent apoptosis

L-amino-acid oxidases (LAO) purified from fungi induce cell death in various mammalian cells including human tumor cell lines. The mechanism, however, remains poorly understood. In this study, we aimed to define a precise mechanism of cell death induced in Jurkat and MCF7 cancer cell lines by ApLAO and CgLAO, LAOs isolated from Amanita phalloides and Clitocybe geotropa, respectively. Cell death induced by both LAOs is shown to be concentration- and time-dependent, with higher toxic effects in Jurkat cells. LAO activity is required for the cytotoxicity. Detailed study on Jurkat cells further demonstrated that ApLAO and CgLAO both induce the intrinsic mitochondrial pathway of apoptosis, accompanied by a time-dependent depolarization of the mitochondrial membrane through the generation of reactive oxygen species. Treatment with the LAOs resulted in an increased ratio of the expression of proapoptotic Bax to that of antiapoptotic Bcl-2, subsequently leading to the activation of caspase-9 and -3. However, the pancaspase inhibitor, Z-VAD-FMK, did not completely abolish the cell death induced by either ApLAO or CgLAO, suggesting an alternative pathway for LAO-induced apoptosis. Indeed, caspase-8 activity in ApLAO- and CgLAO-treated cells was increased. Further, Fas/FasL (Fas ligand) antagonist caused a slight reduction in toxin-induced cell death, supporting the involvement of ApLAO and CgLAO in death-receptor-mediated apoptosis. These results thus provide new evidence that ApLAO and CgLAO induce apoptosis in Jurkat cells via both the intrinsic and extrinsic pathways, although the significantly higher increase of caspase-9 over caspase-8 activity suggests that it is the intrinsic pathway that is the predominant mode of ApLAO- and CgLAO-induced apoptosis.

Role of apoptosis in common variable immunodeficiency and selective immunoglobulin A deficiency

Common variable immunodeficiency (CVID) and selective IgA deficiency (SIgAD) are the most common primary immunodeficiencies in human. Both diseases share clinical manifestation and molecular defects. Increased apoptosis may be one of the mechanisms involved in the pathogenesis of CVID and SIgAD. Elevated apoptosis in this disorder leads to defective long-term survival of B-cells, reduced antibody production, decreased lymphocyte proliferation and defective cytokine secretion. For the first time, we reviewed the role of apoptosis in CVID and SIgAD.

Fas/FasL, Bcl2 and Caspase-8 gene polymorphisms in Chinese patients with rheumatoid arthritis

Apoptosis signals are necessary for maintaining homeostasis and an adequate immune response. Dysregulation of apoptosis-related genes in the immune system has an important impact on autoimmune diseases such as rheumatoid arthritis (RA). Thus, we investigated the association between Fas rs2234767 G/A, FasL rs763110 C/T, Bcl2 rs12454712 T/C, Bcl2 rs17757541 C/G, and Caspase-8 rs1035142 G/T polymorphisms and RA susceptibility in a Chinese population. These five single-nucleotide polymorphisms (SNPs) were studied in a Chinese population consisting of 615 patients with RA and 839 controls. Genotyping was performed using a custom-by-design 48-Plex SNP scan TM kit. Furthermore, we undertook a meta-analysis between FasL rs763110 C/T and RA. This study indicated that Fas rs2234767 and Bcl2 rs17757541 polymorphisms were risk factors for RA. No association was observed between FasL rs763110 C/T, Bcl2 rs12454712 T/C, and Caspase-8 rs1035142 G/T polymorphisms and RA in this study. The results of this meta-analysis suggested no significant association between FasL rs763110 C/T and RA. However, stratification analysis of this meta-analysis indicated that FasL rs763110 C/T increased the risk of Caucasian RA patients. In conclusion, this study demonstrated that Fas rs2234767 G/A and Bcl2 rs17757541 T/C polymorphisms might be associated with an increased risk of RA. This meta-analysis revealed that FasL rs763110 C/T was associated with an increased risk of Caucasian RA patients.

Fas-670A>G polymorphism is not associated with an increased risk of acute myeloid leukemia development

The association between the increased risk of acute myeloid leukemia (AML) and Fas promoter polymorphisms has been reported previously; however, the results are inconclusive. The present study performed one case-control study to investigate the association, and a total of 98 AML patients and 2,014 healthy controls were genotyped. The data showed that the distribution of Fas-670AA, GA and GG genotypes among the AML patients were not significantly different from those of the healthy controls, all P>0.05. Following this a sub-study was conducted to analyze individuals who neither smoked nor drank. The results demonstrated that there was still no significant association between the Fas-670 polymorphism and risk of AML development, all P>0.05. Furthermore, in order to address a more accurate estimation of the association, a meta-analysis was conducted. Data were systematically collected from the Pubmed, EMBASE and the Wanfang Library. A total of 3 studies were included in this meta-analysis, which contained 1,144 AML cases and 3,806 controls. No significant association was detected between the Fas-670A>G polymorphism and AML risk [GA+GG vs. AA: odds ratio (OR) 0.93; 95% confidence interval (CI), 0.79–1.09; GG vs. AA: OR, 1.01; 95% CI, 0.82–1.24; GA vs. AA: OR, 1.12; 95% CI, 0.94–1.32; GG vs. AA+GA: OR, 0.94; 95% CI, 0.79–1.12; G vs. A: OR, 1.01; 95% CI, 0.91–1.12; all P>0.05). The analysis clearly indicated that there was no significant connection between the Fas-670A>G polymorphism and the increased risk of AML.

Significant association between FasL gene -844T/C polymorphism and risk to hepatocellular carcinoma in Egyptian patients

Fas/Fas ligand (FasL) system is the most critical apoptotic signaling entity in the extrinsic apoptotic pathway; hence mutations affecting this pathway may prevent the immune system from the removal of newly-formed tumor cells, and thus lead to tumor formation. The present study investigated the association between the FasL -844T/C polymorphism and the risk of hepatocellular carcinoma (HCC) in a cohort of Egyptian patients and explored the relationship of various clinical and pathological parameters with this single nucleotide polymorphism (SNP). Blood samples were withdrawn from hundred HCC patients and 100 age-, sex- and ethnically matched controls. The FasL -844T/C (rs763110) gene polymorphism was typed from genomic DNA using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) assay. Genotype distributions and allelic frequencies between patients and control subjects showed that the TT homozygous patients were two times more likely to develop HCC (p=0.011). Also, the T allele was found to be a significant risk factor for the disease (OR 1.970, 95% CI 1.250-3.105, p=0.003). No association was detected between different parameters of the disease and the SNP. For the first time, our results suggest that the -844T/C polymorphism in the FasL gene confers risk to HCC. The alarming increase in the incidence of HCC in Egypt encourages further studies to document our results in a larger sample, and recommends more genetic studies hoping to define a genomic risk prediction specific to this cancer in our population.

The cell's dilemma, or the story of cell death: an entertainment in three acts

Cells. They assemble, thrive, and cooperate to compose an organism, simple or complex. And like any living thing, they die. They die by catastrophe, they become sabotaged by condition, or they remove themselves on command from within or without. Each small life is followed by a death, to the benefit or the harm of the whole. Our story, here, is not of how each quietus occurs, but instead, of our ongoing effort to understand these tiny demises, to manipulate them, and to some day control them.

Site disparities in apoptotic variants as predictors of risk for second primary malignancy in patients with squamous cell carcinoma of the head and neck

Background

FAS/FASL promoter variants are considered in altering transcriptional activity of those genes and consequently alter regulation of cell death. However, no studies have investigated whether tumor sites contribute to the association between FAS/FASL polymorphisms and risk for second primary malignancy (SPM).

Method

In this study, FAS670 A > G, FAS1377 G > A, FASL124 A > G, and FASL844C > T polymorphisms were genotyped in 752 OPC and 777 non-OPC patients. Both univariate and multivariable cox proportional hazard models were used to assess the associations.

Results

The univariate and multivariable analyses showed that patients with index OPC and FASL844 CT/TT genotype had significantly increased risk of SPM (cHR, 2.5; 95 % CI, 1.1–5.8, P = 0.043 and aHR, 2.7; 95 % CI, 1.2–6.0, P = 0.032) compared with those with FASL844 CC genotype as the reference group, while index non-OPC patients with FAS670 AG/GG and FasL844 CT/TT genotypes had significantly increased risk of SPM (cHR, 2.2 and 1.8; 95 % CI, 1.2–5.7 and 1.1–3.2; and P = 0.04 and 0.041, respectively and aHR, 2.4 and 1.7; 95 % CI, 1.1–5.1 and 1.0-3.0; and P = 0.043 and 0.049, respectively) compared with their corresponding AA and CC genotypes . Moreover, patients carrying more FAS/FASL variants significantly increased risk of SPM among index non-OPC patients. The stratified analysis showed that smoking status differently modified the associations between FAS/FASL polymorphisms and risk of SPM among index non-OPC from OPC patients.

Conclusion

These results suggested that FAS/FASL polymorphisms might significantly modify SPM risk among patients with SCCHN in a tumor site-specific manner.

Thirty years of BCL-2: translating cell death discoveries into novel cancer therapies

The 'hallmarks of cancer' are generally accepted as a set of genetic and epigenetic alterations that a normal cell must accrue to transform into a fully malignant cancer. It follows that therapies designed to counter these alterations might be effective as anti-cancer strategies. Over the past 30 years, research on the BCL-2-regulated apoptotic pathway has led to the development of small-molecule compounds, known as 'BH3-mimetics', that bind to pro-survival BCL-2 proteins to directly activate apoptosis of malignant cells. This Timeline article focuses on the discovery and study of BCL-2, the wider BCL-2 protein family and, specifically, its roles in cancer development and therapy.

Structural Characterizations of the Fas Receptor and the Fas-Associated Protein with Death Domain Interactions

The Fas receptor is a representative death receptor, and the Fas-associated protein with death domain (FADD) is a crucial adapter protein needed to support the Fas receptor's activity. The Fas-FADD interactions constitute an important signaling pathway that ultimately induces apoptosis or programmed cell death in biological systems. The interactions responsible for this cell-death process are governed by the binding process of the Fas ligand to the Fas, followed by the caspase cascade activation. Using a computational approach, the present communication explores certain essential structural aspects of the Fas-FADD death domains and their interfacial interactions.

Identification of Single Nucleotide Polymorphism Marker and Association Analysis of Marbling Score in Fas Gene of Hanwoo

The Fas (APO-1, TNFRSF6) gene known as a member of the tumor necrosis factor receptor superfamily was selected for DNA marker development in Korean cattle. It is a cell membrane protein and mediates programmed cell death (apoptosis). We discovered single nucleotide polymorphisms (SNPs) within Fas gene in order to develop novel DNA markers related to economical traits at the genomic level. The sequences of whole exon and 1 kb range of both front and back of the gene were determined by direct-sequencing methods using 24 cattle. A total of 55 SNPs were discovered and we selected 31 common polymorphic sites considering their allele frequencies, haplotype-tagging status and linkage disequilibrium (LD) for genotyping in larger-scale subjects. The SNPs were confirmed genotype through the SNaPshot method (n = 274) and were examined for a possible genetic association between Fas polymorphisms and marbling score. So, the SNPs that were identified significant are g.30256G>C, g.31474C>A, g.31940A>G, and g.32982G>A. These results suggest that SNPs of Fas gene were associated with intramuscular fat content of meat quality traits in Korean cattle.

Identification of the Calmodulin-Binding Domains of Fas Death Receptor

The extrinsic apoptotic pathway is initiated by binding of a Fas ligand to the ectodomain of the surface death receptor Fas protein. Subsequently, the intracellular death domain of Fas (FasDD) and that of the Fas-associated protein (FADD) interact to form the core of the death-inducing signaling complex (DISC), a crucial step for activation of caspases that induce cell death. Previous studies have shown that calmodulin (CaM) is recruited into the DISC in cholangiocarcinoma cells and specifically interacts with FasDD to regulate the apoptotic/survival signaling pathway. Inhibition of CaM activity in DISC stimulates apoptosis significantly. We have recently shown that CaM forms a ternary complex with FasDD (2:1 CaM:FasDD). However, the molecular mechanism by which CaM binds to two distinct FasDD motifs is not fully understood. Here, we employed mass spectrometry, nuclear magnetic resonance (NMR), biophysical, and biochemical methods to identify the binding regions of FasDD and provide a molecular basis for the role of CaM in Fas-mediated apoptosis. Proteolytic digestion and mass spectrometry data revealed that peptides spanning residues 209-239 (Fas-Pep1) and 251-288 (Fas-Pep2) constitute the two CaM-binding regions of FasDD. To determine the molecular mechanism of interaction, we have characterized the binding of recombinant/synthetic Fas-Pep1 and Fas-Pep2 peptides with CaM. Our data show that both peptides engage the N- and C-terminal lobes of CaM simultaneously. Binding of Fas-Pep1 to CaM is entropically driven while that of Fas-Pep2 to CaM is enthalpically driven, indicating that a combination of electrostatic and hydrophobic forces contribute to the stabilization of the FasDD-CaM complex. Our data suggest that because Fas-Pep1 and Fas-Pep2 are involved in extensive intermolecular contacts with the death domain of FADD, binding of CaM to these regions may hinder its ability to bind to FADD, thus greatly inhibiting the initiation of apoptotic signaling pathway.

Killing Two Cells with One Stone: Pharmacologic BCL-2 Family Targeting for Cancer Cell Death and Immune Modulation

A crucial component of regulating organismal homeostasis is maintaining proper cell number and eliminating damaged or potentially malignant cells. Apoptosis, or programed cell death, is the mechanism responsible for this equilibrium. The intrinsic apoptotic pathway is also especially important in the development and maintenance of the immune system. Apoptosis is essential for proper positive and negative selection during B- and T-cell development and for efficient contraction of expanded lymphocytes following an immune response. Tight regulation of the apoptotic pathway is critical, as excessive cell death can lead to immunodeficiency while apoptotic resistance can lead to aberrant lymphoproliferation and autoimmune disease. Dysregulation of cell death is implicated in a wide range of hematological malignancies, and targeting various components of the apoptotic machinery in these cases is an attractive chemotherapeutic strategy. A wide array of compounds has been developed with the purpose of reactivating the intrinsic apoptotic pathway. These compounds, termed BH3 mimetics are garnering considerable attention as they gain greater clinical oncologic significance. As their use expands, it will be imperative to understand the effects these compounds have on immune homeostasis. Uncovering their potential immunomodulatory activity may allow for administration of BH3 mimetics for direct tumor cell killing as well as novel therapies for a wide range of immune-based directives. This review will summarize the major proteins involved in the intrinsic apoptotic pathway and define their roles in normal immune development and disease. Clinical and preclinical BH3 mimetics are described within the context of what is currently known about their ability to affect immune function. Prospects for future antitumor immune amplification and immune modulation are then proposed.

Experimental models of hepatotoxicity related to acute liver failure

Acute liver failure can be the consequence of various etiologies, with most cases arising from drug-induced hepatotoxicity in Western countries. Despite advances in this field, the management of acute liver failure continues to be one of the most challenging problems in clinical medicine. The availability of adequate experimental models is of crucial importance to provide a better understanding of this condition and to allow identification of novel drug targets, testing the efficacy of new therapeutic interventions and acting as models for assessing mechanisms of toxicity. Experimental models of hepatotoxicity related to acute liver failure rely on surgical procedures, chemical exposure or viral infection. Each of these models has a number of strengths and weaknesses. This paper specifically reviews commonly used chemical in vivo and in vitro models of hepatotoxicity associated with acute liver failure.

T-cell development of resistance to apoptosis is driven by a metabolic shift in carbon source and altered activation of death pathways

We developed a model system to investigate apoptotic resistance in T cells using osmotic stress (OS) to drive selection of death-resistant cells. Exposure of S49 (Neo) T cells to multiple rounds of OS followed by recovery of surviving cells resulted in the selection of a population of T cells (S49 (OS 4-25)) that failed to die in response to a variety of intrinsic apoptotic stimuli including acute OS, but remained sensitive to extrinsic apoptotic initiators. Genome-wide microarray analysis comparing the S49 (OS 4-25) with the parent S49 (Neo) cells revealed over 8500 differentially regulated genes, with almost 90% of those identified being repressed. Surprisingly, our data revealed that apoptotic resistance is not associated with expected changes in pro- or antiapoptotic Bcl-2 family member genes. Rather, these cells lack several characteristics associated with the initial signaling or activation of the intrinsic apoptosis pathway, including failure to increase mitochondrial-derived reactive oxygen species, failure to increase intracellular calcium, failure to deplete glutathione, failure to release cytochrome c from the mitochondria, along with a lack of induced caspase activity. The S49 (OS 4-25) cells exhibit metabolic characteristics indicative of the Warburg effect, and, despite numerous changes in mitochondria gene expression, the mitochondria have a normal metabolic capacity. Interestingly, the S49 (OS 4-25) cells have developed a complete dependence on glucose for survival, and glucose withdrawal results in cell death with many of the essential characteristics of apoptosis. Furthermore, we show that other dietary sugars such as galactose support the viability of the S49 (OS 4-25) cells in the absence of glucose; however, this carbon source sensitizes these cells to die. Our findings suggest that carbon substrate reprogramming for energy production in the S49 (OS 4-25) cells results in stimulus-specific recognition defects in the activation of intrinsic apoptotic pathways.

FAS -670 A/G polymorphism may be associated with the depletion of CD4(+) T lymphocytes in HIV-1 infection

In this study, the polymorphisms in the FAS and FASL genes was investigated in a sample of 198 HIV-1-seropositive individuals and 191 seronegative controls to evaluate a possible association between polymorphisms and the infection. The identification of the A and G alleles of the FAS -670 polymorphism was accomplished through polymerase chain reaction assays followed by digestion with the restriction enzyme MvaI. The identification of the A and G alleles of the FAS -124 polymorphism and the T and delT alleles of the FAS -169 polymorphism were performed using the amplification-created restriction site method followed by restriction fragment length polymorphism reactions. The comparative analysis of allelic and genotypic frequencies between the groups did not reveal any significant differences. However, the quantitative analysis of CD4(+) T lymphocytes suggests that the G allele of the FAS -670 A/G polymorphism can be a protective factor against the depletion of these cells in the course of an HIV-1 infection. Polymorphisms in the FAS and FASL genes were not associated with the number of CD8(+) T lymphocytes or the plasma viral load. Our findings suggest that the FAS -670 polymorphism may be associated with apoptosis of CD4(+) T lymphocytes after infection by HIV-1.

Therapeutic applications of TRAIL receptor agonists in cancer and beyond

TRAIL/Apo-2L is a member of the TNF superfamily first described as an apoptosis-inducing cytokine in 1995. Similar to TNF and Fas ligand, TRAIL induces apoptosis in caspase-dependent manner following TRAIL death receptor trimerization. Because tumor cells were shown to be particularly sensitive to this cytokine while normal cells/tissues proved to be resistant along with being able to synthesize and release TRAIL, it was rapidly appreciated that TRAIL likely served as one of our major physiologic weapons against cancer. In line with this, a number of research laboratories and pharmaceutical companies have attempted to exploit the ability of TRAIL to kill cancer cells by developing recombinant forms of TRAIL or TRAIL receptor agonists (e.g., receptor-specific mAb) for therapeutic purposes. In this review article we will describe the biochemical pathways used by TRAIL to induce different cell death programs. We will also summarize the clinical trials related to this pathway and discuss possible novel uses of TRAIL-related therapies. In recent years, the physiological importance of TRAIL has expanded beyond being a tumoricidal molecule to one critical for a number of clinical settings - ranging from infectious disease and autoimmunity to cardiovascular anomalies. We will also highlight some of these conditions where modulation of the TRAIL/TRAIL receptor system may be targeted in the future.

Curcumin inhibits apoptosis and brain edema induced by hypoxia-hypercapnia brain damage in rat models

Curcumin, extracted from South Asian spice turmeric, has been determined to have the promising ability in antioxidation and anti-inflammation. However, the effect of curcumin on treating brain damage has been not reported. In this article, the aim was to evaluate the effect of curcumin on cell apoptosis in rats exposed to hypoxia-hypercapnia and explore the therapeutic potential of curcumin in hypoxia-hypercapnia brain damage (HHBD). Sprague Dawley rats were randomly assigned into 3 groups: control group, hypoxia-hypercapnia group and curcumin group. The Fas/FasL expressions in HHBD rats treated by curcumin were measured by immunohistochemical staining and western blotting. The pathological changes of brain cells were observed by transmission electron microscope. Rats with HHBD showed significant increase of Fas/FasL expression and ultrastructural changes in brain tissue cells. Curcumin intervention effectively reversed the Fas/FasL-mediated apoptosis and HHBD-induced brain edema. Curcumin may be a potential therapeutic alternative for HHBD.

Apoptotic variants as predictors of risk of oropharyngeal cancer recurrence after definitive radiotherapy

Single nucleotide polymorphisms (SNPs) in the promoter region of FAS and FASLG may alter their transcriptional activity. Thus, we determined the associations between four FAS and FASLG promoter variants (FAS1377G>A, rs2234767; 670A>G, rs1800682; FASLG844T>C, rs763110 and 124A>G, rs5030772) and the risk of recurrence of squamous cell carcinoma of the oropharynx (SCCOP). We evaluated the associations between FAS and FASLG genetic variants and the risk of recurrence in a cohort of 1,008 patients. The log-rank test and multivariate Cox models were used to evaluate the associations. Compared with patients with common homozygous genotypes of FAS670 and FASLG844 polymorphisms, patients with variant genotypes had lower disease-free survival rates (log-rank p < 0.0001 and p < 0.0001, respectively) and an approximately threefold higher risk of SCCOP recurrence (HR, 3.2;95% CI, 2.2-4.6; and HR, 3.1; 95% CI, 2.2-4.4, respectively) after multivariate adjustment. Furthermore, among patients with HPV16-positive tumors, those with variant genotypes of these two polymorphisms had lower disease-free survival rates (log-rank, p < 0.0001 and p < 0.0001, respectively) and a higher recurrence risk than did patients with common homozygous genotypes (HR, 12.9; 95% CI, 3.8-43.6; and HR, 8.1; 95% CI, 3.6-18.6, respectively), whereas no significant associations were found for FAS1377 and FASLG124 polymorphisms. Our findings suggest that FAS670 and FASLG844 polymorphisms modulate the risk of recurrence of SCCOP, particularly in patients with HPV16-positive tumors. Larger studies are needed to validate these results.

Apoptosis: role in myeloid cell development

Hematopoiesis is the process that generates blood cells in an organism from the pluripotent stem cells. Hematopoietic stem cells are characterized by their ability to undergo self-renewal and differentiation. The self-renewing ability ensures that these pluripotent cells are not depleted from the bone marrow niche. A proper balance between cell death and cell survival is necessary to maintain a homeostatic condition, hence, apoptosis, or programmed cell death, is an essential step in hematopoiesis. Recent studies, however, have introduced a new aspect to this process, citing the significance of the apoptosis mediator, caspase, in cell development and differentiation. Extensive research has been carried out to study the possible role of caspases and other apoptosis related factors in the developmental processes. This review focuses on the various apoptotic factors involved in the development and differentiation of myeloid lineage cells: erythrocytes, megakaryocytes, and macrophages.

HMGB1 Neutralizing Antibody Attenuates Cardiac Injury and Apoptosis Induced by Hemorrhagic Shock/Resuscitation in Rats

High-mobility group box 1 (HMGB1) and its natural receptor, Toll-like receptor-4 (TLR4), are involved in various infectious or noninfectious diseases including hemorrhagic shock. HMGB1 neutralizing antibody (anti-HMGB1 monoclonal antibody (mAb)) treatment was shown to alleviate ischemia-reperfusion injury effectively. The aim of this study was to explore whether and by what mechanisms anti-HMGB1 mAb attenuates hemorrhagic shock and resuscitation (HS/R)-induced cardiac injury. Employing rat HS/R models, we found that anti-HMGB1 mAb treatment improved HS/R-induced cardiac function deterioration, attenuated cardiac enzyme elevation, improved ATP loss, and protected cardiac tissue. Anti-HMGB1 mAb also inhibited the production of inflammatory factors interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α). Moreover, anti-HMGB1 mAb reduced apoptotic responses by suppressing activated caspase-3 and reversing apoptotic gene expression of capase-3, Bax, and Bcl-2 in rat cardiac tissue. Moreover, anti-HMGB1 mAb decreased HS/R-induced HMGB1 and TLR4 expression elevation. We further confirmed that anti-HMGB1 mAb inhibited lipopolysaccharide-activated HGMB1 and TLR4 expression and decreased inflammatory factors IL-1β, IL-6, and TNF-α at the cellular level. It was concluded that anti-HMGB1 mAb treatment protects rats from cardiac injury induced by HS/R, and the beneficial effects may be related to its inhibitory effects on the HMGB1-TLR4 axis.

Overexpression of Telomerase Protects Human and Murine Lung Epithelial Cells from Fas- and Bleomycin-Induced Apoptosis via FLIP Upregulation

High doses of bleomycin administered to patients with lymphomas and other tumors lead to significant lung toxicity in general, and to apoptosis of epithelial cells, in particular. Apoptosis of alveolar epithelium is an important step in the pathogenesis of bleomycin-induced pulmonary fibrosis. The Fas-FasL pathway is one of the main apoptotic pathways involved. Telomerase is a ribonucleoprotein RNA-dependent DNA polymerase complex consisting of an RNA template and a catalytic protein, telomerase reverse transcriptase (TERT). Telomerase also possess extra-telomeric roles, including modulation of transcription of anti-apoptotic genes, differentiation signals, and more. We hypothesized that telomerase overexpression affects Fas-induced epithelial cell apoptosis by an extra-telomeric role such as regulation of anti-apoptotic genes, specifically FLICE-like inhibitory protein (FLIP). Telomerase in mouse (MLE) and human (A549) lung epithelial cell lines was upregulated by transient transfection using cDNA hTERT expression vector. Telomerase activity was detected using a real-time PCR-based system. Bleomycin, and bleomycin-induced Fas-mediated apoptosis following treatment with anti-Fas activating mAb or control IgG, were assessed by Annexin V staining, FACS analysis, and confocal microscopy; caspase cleavage by Western blot; FLIP or Fas molecule detection by Western blot and flow cytometry. hTERT transfection of lung epithelial cells resulted in a 100% increase in their telomerase activity. Fas-induced lung epithelial cell apoptosis was significantly reduced in hTERT-transfected cells compared to controls in all experiments. Lung epithelial cells with increased telomerase activity had higher levels of FLIP expression but membrane Fas expression was unchanged. Upregulation of hTERT+ in human lung epithelial cells and subsequent downregulation of FLIP by shFLIP-RNA annulled hTERT-mediated resistance to apoptosis. Telomerase-mediated FLIP overexpression may be a novel mechanism to confer protection from apoptosis in bleomycin-exposed human lung epithelial cells.

Targeting TNF-related apoptosis-inducing ligand (TRAIL) receptor by natural products as a potential therapeutic approach for cancer therapy

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been shown to selectively induce apoptotic cell death in various tumor cells by engaging its death-inducing receptors (TRAIL-R1 and TRAIL-R2). This property has led to the development of a number of TRAIL-receptor agonists such as the soluble recombinant TRAIL and agonistic antibodies, which have shown promising anticancer activity in preclinical studies. However, besides activating caspase-dependent apoptosis in several cancer cells, TRAIL may also activate nonapoptotic signal transduction pathways such as nuclear factor-kappa B, mitogen-activated protein kinases, AKT, and signal transducers and activators of transcription 3, which may contribute to TRAIL resistance that is being now frequently encountered in various cancers. TRAIL resistance can be overcome by the application of efficient TRAIL-sensitizing pharmacological agents. Natural compounds have shown a great potential in sensitizing cells to TRAIL treatment through suppression of distinct survival pathways. In this review, we have summarized both apoptotic and nonapoptotic pathways activated by TRAIL, as well as recent advances in developing TRAIL-receptor agonists for cancer therapy. We also briefly discuss combination therapies that have shown great potential in overcoming TRAIL resistance in various tumors.