[FAS- and TNF-dependent ways participation in apoptosis mechanisms in hypotalumus in physiological and pathological aging.]

The cell resistance to apoptosis can be related to the activity of cytokine-dependent signaling. So, the aim of the work is to investigate the mechanisms of cytokine-dependent FAS/TNF-mediated regulation of apoptosis of neurosecretory cells in the physiological and pathological (overexpression of the oncogene HER-2/Neu) aging. HER2/Neu transgenic accelerated aged mice of different ages and wild type FVB/N were examined. The apoptosis level of neurons in hypothalamic sections (supraoptic and paraventricular nuclei) (TUNEL) and expression of caspase-8, CD178 (FASL), FAS, FADD, TRADD (Western blotting) was determined. Participation of the proinflammatory component in the aging process is shown. FAS, adapter proteins associated with the death domain (FADD and TRADD), caspase-8 expression is activated in hypothalamus in FVB/N mice (wild type) during aging, and it correlates with an increase in the apoptosis level. HER-2/Neu expression leads to the extrinsic apoptotic pathway suppression. In this case, the reception of an apoptotic signal (FAS-receptor expression) and its further transmission (expression of FADD and TRADD) is suppressed. However, in young transgenic mice, increased expression of TRADD can activate one of the survival ways - NF-κB, ERK or PI3K-AKT cascade. Thus, the HER-2/Neu tyrosine kinase receptor plays a role in the mechanism of cell resistance to age-dependent apoptosis, and the FAS/TNF-signaling pathway is one of the targets of HER-2/Neu.

Interferon-γ affects leukemia cell apoptosis through regulating Fas/FasL signaling pathway

OBJECTIVE

Imbalance of hematopoietic cell proliferation and apoptosis is one of the major causes of leukemia. Enhanced cell proliferation and reduced apoptosis lead to hemocytes accumulation. Fas/FasL signaling pathway promotes cell apoptosis. This study investigated the impact of interferon γ (IFN-γ) on chronic myelogenous leukemia cell proliferation and apoptosis to elucidate its interaction with Fas/FasL signaling pathway.

PATIENTS AND METHODS

Leukemia K562 cells were routinely cultivated and treated with 10 U/ml, 100 U/ml, and 1000 U/ml interferon for 12 h, 24 h, and 48 h, respectively. MTT assay was applied to test cell proliferation. TUNEL assay was adopted to determine cell apoptosis. Western blot was selected to detect Fas/FasL expression.

RESULTS

Different concentrations of IFN-γ inhibited cell proliferation at various time points. IFN-γ at 1000 U/ml treatment for 48 h exhibited the strongest suppressive effect on cell proliferation (p < 0.05). IFN-γ intervention enhanced K562 cell apoptosis with concentration and time dependence (p < 0.05). Fas and FasL proteins expressions upregulated after treated by IFN-γ following dose elevation and time extension (p < 0.05).

CONCLUSIONS

IFN-γ inhibits leukemia K562 cell proliferation and promotes cell apoptosis via facilitating Fas and FasL proteins expressions.

Fluoride reduced the immune privileged function of mouse Sertoli cells via the regulation of Fas/FasL system

Previous investigations have demonstrated the adverse impacts of fluoride on Sertoli cells (SCs), such as oxidative stress and apoptosis. SCs are the crucial cellular components that can create the immune privileged environment in testis. However, the effect of fluoride on SCs immune privilege is unknown. In this study, mouse SCs were exposed to sodium fluoride with varying concentrations of 10^-5, 10^-4, and 10^-3 mol/L to establish the model of fluoride-treated SCs (F-SCs) in vitro. After 48 h of incubation, F-SCs were transplanted underneath the kidney capsule of mice for 21 days, or cocultured with spleen lymphocytes for another 48 h. Immunohistochemical analysis of GATA4 in SCs grafts underneath kidney capsule presented less SCs distribution and obvious immune cell infiltration in F-SCs groups. In addition, the levels of FasL protein and mRNA in non-cocultured F-SCs decreased with the increase of fluoride concentration. When cocultured with F-SCs, lymphocytes presented significantly high cell viability and low apoptosis in F-SCs groups. Protein and mRNA expressions of FasL in cocultured F-SCs and Fas in lymphocytes were reduced, and the caspase 8 and caspase 3 mRNA levels were also decreased in fluoride groups in a dose-dependent manner. These findings indicated that fluoride influenced the testicular immune privilege through disturbing the Fas/FasL system.

Soluble Fas Concentrations in the Follicular Fluid and Oocyte-Cumulus Complex Culture Medium From Women Undergoing In Vitro Fertilization: Association With Oocyte Maturity, Fertilization, and Embryo Quality

OBJECTIVE

Because soluble Fas (sFas) inhibits Fas-mediated apoptosis by preventing death signal transduction, we determined sFas concentrations in the follicular fluid (FF) and oocyte-cumulus complex culture medium (CM) from women undergoing in vitro fertilization (IVF) in order to associate its concentrations with oocyte maturity, fertilization, and embryo quality.

METHODS

We studied 82 follicles from 11 healthy women (mean age, 35.4 +/- 3.8 years) using a long protocol for IVF treatment. Individual FF and matched CM samples were immediately centrifuged at 4C and sFas concentrations were determined by sandwich enzyme-linked immunosorbent assays.

RESULTS

sFas concentrations were significantly higher in FF than in CM (P <.0001) and when oocytes were mature rather than immature (P <.002). Of 70 mature and 12 immature oocytes, 56 (80%) and two (16.6%), respectively, were fertilized. sFas concentrations in CM were significantly lower when mature oocytes were fertilized versus nonfertilized (P <.005). sFas concentrations in FF and CM were significantly related in an inverse manner to embryo quality (P = .004 and P = .0002, respectively).

CONCLUSION

FF and CM from women undergoing IVF contain sFas. The latter has anti-apoptotic properties and levels are higher: in FF when oocytes are mature and in CM when oocytes are nonfertilized. Furthermore, FF and CM sFas concentrations are negatively correlated with embryo quality.

Efficient analysis of mouse genome sequences reveal many nonsense variants

Genetic polymorphisms in coding genes play an important role when using mouse inbred strains as research models. They have been shown to influence research results, explain phenotypical differences between inbred strains, and increase the amount of interesting gene variants present in the many available inbred lines. SPRET/Ei is an inbred strain derived from Mus spretus that has ∼1% sequence difference with the C57BL/6J reference genome. We obtained a listing of all SNPs and insertions/deletions (indels) present in SPRET/Ei from the Mouse Genomes Project (Wellcome Trust Sanger Institute) and processed these data to obtain an overview of all transcripts having nonsynonymous coding sequence variants. We identified 8,883 unique variants affecting 10,096 different transcripts from 6,328 protein-coding genes, which is about 28% of all coding genes. Because only a subset of these variants results in drastic changes in proteins, we focused on variations that are nonsense mutations that ultimately resulted in a gain of a stop codon. These genes were identified by in silico changing the C57BL/6J coding sequences to the SPRET/Ei sequences, converting them to amino acid (AA) sequences, and comparing the AA sequences. All variants and transcripts affected were also stored in a database, which can be browsed using a SPRET/Ei M. spretus variants web tool (www.spretus.org), including a manual. We validated the tool by demonstrating the loss of function of three proteins predicted to be severely truncated, namely Fas, IRAK2, and IFNγR1.

The signaling pathways by which the Fas/FasL system accelerates oocyte aging

In spite of great efforts, the mechanisms for postovulatory oocyte aging are not fully understood. Although our previous work showed that the FasL/Fas signaling facilitated oocyte aging, the intra-oocyte signaling pathways are unknown. Furthermore, the mechanisms by which oxidative stress facilitates oocyte aging and the causal relationship between Ca2+ rises and caspase-3 activation and between the cell cycle and apoptosis during oocyte aging need detailed investigations. Our aim was to address these issues by studying the intra-oocyte signaling pathways for Fas/FasL to accelerate oocyte aging. The results indicated that sFasL released by cumulus cells activated Fas on the oocyte by increasing reactive oxygen species via activating NADPH oxidase. The activated Fas triggered Ca2+ release from the endoplasmic reticulum by activating phospholipase C-γ pathway and cytochrome c pathway. The cytoplasmic Ca2+ rises activated calcium/calmodulin-dependent protein kinase II (CaMKII) and caspase-3. While activated CaMKII increased oocyte susceptibility to activation by inactivating maturation-promoting factor (MPF) through cyclin B degradation, the activated caspase-3 facilitated further Ca2+releasing that activates more caspase-3 leading to oocyte fragmentation. Furthermore, caspase-3 activation and fragmentation were prevented in oocytes with a high MPF activity, suggesting that an oocyte must be in interphase to undergo apoptosis.

Memory T cell-driven differentiation of naive cells impairs adoptive immunotherapy

Adoptive cell transfer (ACT) of purified naive, stem cell memory, and central memory T cell subsets results in superior persistence and antitumor immunity compared with ACT of populations containing more-differentiated effector memory and effector T cells. Despite a clear advantage of the less-differentiated populations, the majority of ACT trials utilize unfractionated T cell subsets. Here, we have challenged the notion that the mere presence of less-differentiated T cells in starting populations used to generate therapeutic T cells is sufficient to convey their desirable attributes. Using both mouse and human cells, we identified a T cell-T cell interaction whereby antigen-experienced subsets directly promote the phenotypic, functional, and metabolic differentiation of naive T cells. This process led to the loss of less-differentiated T cell subsets and resulted in impaired cellular persistence and tumor regression in mouse models following ACT. The T memory-induced conversion of naive T cells was mediated by a nonapoptotic Fas signal, resulting in Akt-driven cellular differentiation. Thus, induction of Fas signaling enhanced T cell differentiation and impaired antitumor immunity, while Fas signaling blockade preserved the antitumor efficacy of naive cells within mixed populations. These findings reveal that T cell subsets can synchronize their differentiation state in a process similar to quorum sensing in unicellular organisms and suggest that disruption of this quorum-like behavior among T cells has potential to enhance T cell-based immunotherapies.

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.

Effects of a simulated tennis match on lymphocyte subset measurements

Tennis is an activity requiring both endurance and anaerobic components, which could have immunosuppressive effects postexercise.

PURPOSE

The purpose of this investigation was to determine the effect of a simulated tennis match on apoptotic and migratory markers on lymphocyte subsets.

METHOD

Male high school (n = 5) and college (n = 3) tennis players (M(age) = 18.9 +/- 3.3 years) completed 10 sets of a tennis protocol including serves, forehand strokes, and backhand groundstrokes with 1-min rest periods between sets. Apoptosis antigen 1 receptor (CD95) and chemokine receptor fractalkine (CX3CR1) expression was analyzed on helper T lymphocytes (CD4+), cytotoxic T lymphocytes (CD8+), and B lymphocytes (CD19+) twice, at resting baseline and immediately after all 10 sets of the tennis protocol.

RESULTS

An increase was observed in each lymphocyte subtype (p < .02, effect size = .41), and comparison of absolute changes revealed increases in CD4+/CD95+, CD8+/CD95+, and CD8+/CX3CR1 lymphocytes following the tennis protocol (p < .01, effect size = .43), but not in CD19+ cells.

CONCLUSIONS

A simulated tennis match has adequate intensity to induce immune modulations in terms of increased cell death and cellular migration in T lymphocyte subsets. Lymphocytopenia following tennis play is influenced by both apoptotic and migratory mechanisms.

Exercise-induced leukocyte apoptosis

Physical exercise is well known to affect leukocyte numbers and function. While regular exercise training has been shown to enhance specific immune functions, acute bouts of intensive exercise often lead to a pro-inflammatory response accompanied by a transient lymphocytopenia and neutrophilia. It can be assumed, that lymphocytopenia can be attributed at least partially to an enhanced lymphocyte apoptosis. In contrast, regulation of neutrophil apoptosis after exercise remains controversial since studies demonstrated both an up-regulation as well as a down-regulation of cell death. However, these discrepancies may be due to differences in exercise protocols, subjects' fitness levels, and to different methodological approaches. Two major signalling pathways of exercise induced apoptosis have been identified. First the external receptor mediated pathway using death receptors, and second the internal, oxidative-mediated pathway which encompasses the mitochondria. Potential apoptosis modulating mediators are reactive oxygen species (ROS), glucocorticoids and cytokines which are part of the systemic inflammatory response evoked after acute intensive exercise. Finally, the physiological impact and clinical relevance of leukocyte apoptosis will be discussed. On the one hand, exercise-induced apoptosis might be a mechanism to remove activated and potentially autoreactive immune cells. On the other hand, apoptosis might be a regulatory mechanism which is necessary for tissue reorganization and adaptational training processes.

GABA tea prevents cardiac fibrosis by attenuating TNF-alpha and Fas/FasL-mediated apoptosis in streptozotocin-induced diabetic rats

GABA tea is a tea product that contains a high level of gamma-aminobutyric acid (GABA). This study investigated the effects of GABA tea on the heart in a diabetic rat model. Male Wistar rats were injected with 55mg/kg streptozotocin (STZ) to induce diabetes for 2weeks and then orally given dosages of 4.55 and 45.5mg/kg/day GABA tea extract for 6weeks. The results revealed that fasting blood glucose levels returned to normal levels in GABA tea-treated diabetic rats, but not in the untreated diabetic rats. Additionally, GABA tea effectively inhibited cardiac fibrosis induced by STZ. Further experiments showed that the STZ-induced protein levels of tumor necrosis factor-alpha (TNF-alpha), Fas, activated caspase-8 and caspase-3 were significantly inhibited by the GABA tea treatment. Therefore, our data suggest that the inhibiting effect of GABA tea on STZ-induced cardiac fibrosis in diabetic rats may be mediated by reducing blood glucose and further attenuating TNF-alpha expression and/or Fas/Fas ligand (FasL)-mediated apoptosis. These findings will provide implications for the potential anti-diabetic properties of GABA tea.

Mechanism of cadmium induced apoptosis in human peripheral blood lymphocytes: the role of p53, Fas and Caspase-3

Cadmium (Cd) is a major pollutant of environment. It can be fatal to human. In spite of bulk of research and literatures, the mechanism of a fatality against human is still not understood completely. Toxic and carcinogenic effects of Cd in rodents and humans are well known. However, effects of Cd on induction of apoptosis are still elusive. This study indicates immunosuppression and immunotoxicity due to Cd exposure. Present study was undertaken to determine the mechanism of cell death in vitro in human peripheral blood lymphocytes induced by Cd. Our findings suggest the toxicity due to Cd is attributed to programmed cell death-apoptosis. IC₅₀ was calculated at 21.74 μM. A significant increase of expression of the pro-apoptotic genep53, Fas and Caspase-3 in human lymphocytes was found. Cd induced p53-dependent apoptosis through cooperation between Bak upregulation without changing the Bcl-2 and Bax expression. Data of this study compel to speculate that apoptosis may also be attributed to CD95/Fas complex formation, and p53 direct apoptogenic potential at mitochondria. It was confirmed by the increased expression of Caspase-3. Although, this work does not address all the questions regarding the mechanism of Cd induced apoptosis, but these findings establish an important role of p53 and mitochondrial function during apoptosis in human lymphocyte. Moreover, based upon our findings, the role of Fas in Cd induced apoptosis is also undeniable. Hence further investigations are required to understand the different mechanism involved into apoptosis of lymphocytes due to Cd exposure.

[Role of bone marrow-derived mesenchymal stem cells in treating colitis through Fas/FasL-mediated immune regulation]

OBJECTIVE

To investigate the difference in the therapeutic effects of bone marrow-derived mesenchymal stem cells (BMSCs) of mice from ovariectomy (OVX) group and sham group in treating colitis, and then further study the differences of Fas/FasL expression and downstream T cell migration and apoptosis between the two groups.

METHODS

The osteoporosis animal models were set up by ovariectomy in C57BL6 mice. Meanwhile, 3% dextran sulfate sodium (DSS) was administered for inducing colitis. We compared the therapeutic effects of BMSCs from OVX and sham groups in treating colitis, in addition, detected the expression of Fas/FasL in BMSCsby means of RT-PCR and Western blotting. The ability of BMSCs from the two groups of inducing T cell migaration and apoptosis was also detected.

RESULTS

Compared with the sham group, BMSCs from OVX mice expressed a lower level of Fas/FasL and displayed a decreased ability of inducing T cell migration and apoptosis, thus leading to an inferior therapeutic effect in treating colitis in animal models.

CONCLUSION

Fas/FasL expression of BMSCs from the OVX mice is down regulated, thus leading to a decrease of the migration and apoptosis for T cells from mouse colitis.

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.

CEACAM1 regulates Fas-mediated apoptosis in Jurkat T-cells via its interaction with β-catenin

CEACAM1 (Carcinoembryonic Antigen Cell Adhesion molecule 1), an activation induced cell surface marker of T-cells, modulates the T-cell immune response by inhibition of the T-cell and IL-2 receptors. Since T-cells undergo activation induced cell death via Fas activation, it was of interest to determine if this pathway was also affected by CEACAM1. Previously, we identified a novel biochemical interaction between CEACAM1 and the armadillo repeats of β-catenin in Jurkat cells, in which two critical residues, H469 and K470 of the cytoplasmic domain of CEACAM1-4L played an essential role; while in other studies, β-catenin was shown to regulate Fas-mediated apoptosis in Jurkat cells. CEACAM1 expression in Jurkat cells leads to the re-distribution of β-catenin to the actin cytoskeleton as well as inhibition of β-catenin tyrosine phosphorylation and its degradation after Fas stimulation. As a result, Fas-mediated apoptosis in these cells was inhibited. The K470A mutation of CEACAM1 partially rescued the inhibitory effect, in agreement with the prediction that a CEACAM1-β-catenin interaction pathway is involved. Although CEACAM1 has two ITIMs, they were not tyrosine-phosphorylated upon Fas ligation, indicating an ITIM independent mechanism; however, mutation of the critical residue S508, located between the ITIMs, to aspartic acid and a prerequisite for ITIM activation, abrogates the inhibitory activity of CEACAM1 to Fas-mediated apoptosis. Since Fas-mediated apoptosis is a major form of activation-induced cell death, our finding supports the idea that CEACAM1 is a general inhibitory molecule for T-cell activation utilizing a variety of pathways.

Human β-cell killing by autoreactive preproinsulin-specific CD8 T cells is predominantly granule-mediated with the potency dependent upon T-cell receptor avidity

The end-stage immunopathology of type 1 diabetes resulting in β-cell destruction appears to be strongly dominated by cytotoxic CD8 T lymphocytes (CD8 T cells). However, the mechanism of cytotoxicity used by autoreactive CD8 T cells in the human setting remains unknown. Using type 1 diabetes patient-derived preproinsulin-specific CD8 T-cell clones recognizing either an HLA-A2 (A*0201) or HLA-A24 (A*2402)-restricted epitope (peptide of preproinsulin [PPI](15-24), ALWGPDPAAA; or PPI(3-11), LWMRLLPLL), we assessed the use of conventional mediators of cytotoxicity in the destruction of human β-cells in vitro compared with virus-specific cytotoxic CD8 T-cell clones. We show that PPI-specific CD8 T-cell clones are mainly reliant upon cytotoxic degranulation for inducing β-cell death. Furthermore, we find that in comparison with virus-specific CD8 T cells, there are differences in the killing potency of PPI-specific CD8 T cells that are not due to cell-intrinsic differences, but rather are mediated by differences in strength of signaling by peptide-HLA ligands. The study highlights the regulation of β-cell killing as a potential point for therapeutic control, including the possibility of blocking autoreactive CD8 T-cell function without impacting upon general immune competence.

Interventions to improve chronic cyclosporine A nephrotoxicity through inhibiting renal cell apoptosis: a systematic review

OBJECTIVE

To reveal interventions for chronic cyclosporine A nephrotoxicity (CCN) and provide new targets for further studies, we analyzed all relevant studies about interventions in renal cell apoptosis.

DATA SOURCES

We collected all relevant studies about interventions for cyclosporine A (CsA)-induced renal cell apoptosis in Medline (1966 to July 2010), Embase (1980 to July 2010) and ISI (1986 to July 2010), evaluated their quality, extracted data following PICOS principles and synthesized the data.

STUDY SELECTION

We included all relevant studies about interventions in CsA-induced renal cell apoptosis no limitation of research design and language) and excluded the duplicated articles, meeting abstracts and reviews without specific data.

RESULTS

There were three kinds of intervention, include anti-oxidant (sulfated polysaccharides, tea polyphenols, apigenin, curcumin, spirulina, etc), biologics (recombinant human erythropoietin (rhEPO), a murine pan-specific transforming growth factor (TGF)-beta-neutralizing monoclonal antibody1D11, cartilage oligomeric matrix protein (COMP)-angiopoietin-1 and hepatocyte growth factor (HGF) gene), and other drugs (spironolactone, rosiglitazone, pirfenidone and colchicine). These interventions significantly improved the CCN, renal cell apoptosis and renal dysfunction through intervening in four apoptotic pathways in animals or protected renal cells from apoptosis induced by CsA and increased cell survival through respectively four pathways in vitro.

CONCLUSIONS

There are three group interventions for CCN. Especially anti-oxidant drugs can significantly improve CCN, renal cell apoptosis and renal dysfunction. Many drugs can improve CCN through intervening in Fas/Fas ligand or mitochondrial pathway with sufficient evidences. Angiotensin II, nitric oxide (NO) and endoplasmic reticulum (ER) pathways will be new targets for CCN.

Altered expression of survivin, Fas and FasL contributed to cervical cancer development and metastasis

OBJECTIVE

To evaluate the expression of apoptosis-related genes and their correlation with prognosis in cervical cancer patients.

MATERIALS AND METHODS

The expressions of Survivin, Fas and FasL in tissues of cervical cancer, cervical intraepithelial neoplasia (CIN), chronic cervicitis and normal cervix wer detected by immunohistochemical staining, and the relationship between the expression of Survivin, Fas and FasL and clinical pathologic characteristics of cervical cancer was correlation analysis.

RESULTS

The positive expression rates of Survivin and FasL in cervical cancer tissues were significantly higher than those in tissues of normal cervix, chronic cervicitis and CIN (p < 0.05), but lower positive expression rate of Fas was observed in cervical cancer tissues when compared with that in normal cervix, chronic cervicitis and CIN tissues (p < 0.05). The expression of Survivin was significantly correlated with clinical staging and lymph node metastases of cervical cancer (p < 0.05). The expression of FasL was correlated with lymph node metastases, clinical staging and pathological grading of cervical cancer (p < 0.05). The expression of Survivin was negatively correlated with that of Fas (r = -0.517, p < 0.01), but positively correlated with that of FasL (r = 0.381, p < 0.01) in tissues of cervical cancer.

CONCLUSIONS

The up-regulated expression of Survivin and FasL and down-regulated expression of Fas may be involved in the carcinogenesis and development of cervical cancer. The expression of FasL may be one of the prediction indexes for disease progression and prognosis in cervical cancer.

Correlated expression of Fas, NF-kappaB, and VEGF-C in infiltrating ductal carcinoma of the breast

OBJECTIVE

To investigate the expressions of Fas, NF-kappaB, and vascular endothelial growth factor-C (VEGF-C) in infiltrating ductal carcinoma of the breast and provide scientific basis for early diagnosis and prognosis of breast cancer.

MATERIALS AND METHODS

The immunohistochemical technique (SP method) was used to detect expression of Fas, NF-kappaB, and VEGF-C in 137 cases of breast-infiltrating ductal carcinoma, 17 cases of intraductal carcinoma of the breast, and 20 cases of normal breast tissues, and analyze its relationship with clinicopathologic factors of breast cancer and patients' survival rate, as well as the correlation among their expression, clinicopathologic factors, and survival rate.

RESULTS

Fas expression was less commonly detected in infiltrating ductal carcinoma than in intraductal carcinoma and normal tissue. In contrast, both NF-kappaB and VEGF-C were more commonly detected in infiltrating ductal carcinoma than in intraductal carcinoma and normal tissue. Fas expression was correlated with tumor size, histological grade, and clinicopathological stage; NF-kappaB expression was correlated with tumor size, histological grade, lymph node metastasis; VEGF-C expression was correlated with lymph node metastasis and clinical and pathological stages of breast cancer (p < or = 0.05). Spearman rank correlation analysis revealed a negative correlation between Fas expression and both NF-kappaB and VEGF-C expression in infiltrating breast cancer (p < 0.05) Additionally, Kaplan-Meier survival analysis demonstrated that five-year survival was higher for patients with Fas-positive samples but lower for those with VEGF-C-positive samples.

CONCLUSIONS

The present results demonstrate that Fas and NF-B play a role in the initiation and development of breast cancer, while VEGF-C appears to promote lymph node metastasis. Thus, these proteins may serve as useful diagnostic and prognostic markers of invasive breast cancer.

Fas/FasL-mediated apoptosis and inflammation are key features of acute human spinal cord injury: implications for translational, clinical application

The Fas/FasL system plays an important role in apoptosis, the inflammatory response and gliosis in a variety of neurologic disorders. A better understanding of these mechanisms could lead to effective therapeutic strategies following spinal cord injury (SCI). We explored these mechanisms by examining molecular changes in postmortem human spinal cord tissue from cases with acute and chronic SCI. Complementary studies were conducted using the in vivo Fejota™ clip compression model of SCI in Fas-deficient B6.MRL-Fas-lpr (lpr) and wild-type (Wt) mice to test Fas-mediated apoptosis, inflammation, gliosis and axonal degeneration by immunohistochemistry, Western blotting, gelatin zymography and ELISA with Mouse 32-plex cytokine/chemokine panel bead immunoassay. We report novel evidence that shows that Fas-mediated apoptosis of neurons and oligodendrocytes occurred in the injury epicenter in all cases of acute and subacute SCI and not in chronic SCI or in control cases. We also found significantly reduced apoptosis, expression of GFAP, NF-κB, p-IKappaB and iba1, increased number of CD4 positive T cells and MMP2 expression and reduced neurological dysfunction in lpr mice when compared with Wt mice after SCI. We found dramatically reduced inflammation and cytokines and chemokine expression in B6.MRL-Fas-lpr mice compared to Wt mice after SCI. In conclusion, we report multiple lines of evidence that Fas/FasL activation plays a pivotal role in mediating apoptosis, the inflammatory response and neurodegeneration after SCI, providing a compelling rationale for therapeutically targeting Fas in human SCI.

Involvement of FOXO transcription factors, TRAIL-FasL/Fas, and sirtuin proteins family in canine coronavirus type II-induced apoptosis

n our previous study, we have shown that canine coronavirus type II (CCoV-II) activates both extrinsic and intrinsic apoptotic pathway in a canine fibrosarcoma cell line (A-72 cells). Herein we investigated the role of Sirtuin and Forkhead box O (FOXO) families in this experimental model using Nortern Blot and Western Blot analysis. Our results demonstrated that mitochondrial SIRT3 and SIRT4 protein expression increased from 12 and 24 h post infection (p.i.) onwards, respectively, whereas the nuclear SIRT1 expression increased during the first 12 h p.i. followed by a decrease after 36 h p.i., reaching the same level of control at 48 h p.i. Sirtuins interact with/and regulate the activity of FOXO family proteins, and we herein observed that FOXO3A and FOXO1 expression increased significantly and stably from 12 h p.i. onwards. In addition, CCoV-II induces a remarkable increase in the expression of TNF-related apoptosis-inducing ligand (TRAIL), while we observed a slight up-regulation of FasL/Fas at 36 p.i. with a decrease of both proteins at the end of infection. Furthermore, we found that virus infection increased both bax translocation into mitochondria and decreased bcl-2 expression in cytosol in a time-dependent manner.These data suggest that FOXO transcription factors mediate pro-apoptotic effects of CCoV-II, in part due to activation of extrinsic apoptosis pathway, while some Sirtuin family members (such as SIRT3 and SIRT4) may be involved in intrinsic apoptotic pathway. Moreover, these results propose that TRAIL is an important mediator of cell death induced by CCoV-II during in vitro infection.

Overexpression of gastrokine 1 in gastric cancer cells induces Fas-mediated apoptosis

Gastrokine 1 (GKN1) is involved in the replenishment of the surface lumen epithelial cell layer, in maintaining the mucosal integrity, and could play a role in cell proliferation and differentiation. In fact, after injury of the gastric mucosa, restoration may occur very rapidly in the presence of GKN1. In contrast, if the protein is downregulated, the repair process may be hampered; however, application of GKN1 to gastrointestinal cells promoted epithelial restoration. Because GKN1 possesses some mitogenic effects on intestinal epithelial cells (IEC-6) whereas this protein was also capable of inhibiting proliferation in gastric cancer cells (MKN28), we decided to study its involvement in apoptosis to understand the role of GKN1 in the modulation of inflammatory damage or tumorigenesis in gastric mucosa. We found by cytofluorimetry, Western blot and RT-PCR that the overexpression of GKN1 in gastric cancer cell lines (AGS and MKN28) stimulated the expression of Fas receptor. Moreover, compared to control cells, a significant increase of apoptosis, evaluated by TUNEL, was observed when GKN1 transfected cells were treated with a monoclonal antibody (IgM) anti-Fas. The activation of Fas expression was also observed by the overexpression of GKN1 in other cancer cell lines. Moreover, in GKN1-overexpressing gastric cancer cells exposed to FasL, the activation of caspase-3 was also observed by Western blot and fluorescence assays. Our data represent the first report for GKN1 as modulator of apoptotic signals and suggest that GKN1 might play an important role for tissue repair during the early stages of neoplastic transformation.

Gonadal steroids modulate Fas-induced apoptosis of lactotropes and somatotropes

We have previously reported that Fas activation induces apoptosis of anterior pituitary cells from rats at proestrus but not at diestrus and in an estrogen-dependent manner. In this study, we evaluated the effect of Fas activation on apoptosis of lactotropes and somatotropes during the estrous cycle and explored the action of gonadal steroids on Fas-induced apoptosis. Also, we studied whether changes in Fas expression are involved in the apoptotic response of anterior pituitary cells. Fas activation increased the percentage of TUNEL-positive lactotropes and somatotropes at proestrus but not at diestrus. FasL triggered apoptosis of somatotropes only when cells from ovariectomized rats were cultured in the presence of 17 β-estradiol (E2). Progesterone (P4) blocked the apoptotic action of the Fas/FasL system in lactotropes and somatotropes incubated with E2. Both E2 and P4 increased the percentage of cells expressing Fas at the cell membrane. Our results show that Fas activation induces apoptosis of lactotropes and somatotropes at proestrus but not at diestrus. Gonadal steroids may be involved in the apoptotic response of lactotropes and somatotropes, suggesting that Fas activation is implicated in the renewal of these pituitary subpopulations during the estrous cycle. The effect of gonadal steroids on Fas expression may be only partially involved in regulation of the Fas/FasL apoptotic pathway in the anterior pituitary gland.

Identification of c-FLIP(L) and c-FLIP(S) as critical regulators of death receptor-induced apoptosis in pancreatic cancer cells

BACKGROUND

Evasion of apoptosis is a hallmark of pancreatic cancer. However, the underlying mechanisms are still only partly understood and may involve antiapoptotic proteins such as c-FLIP. Here, the role of c-FLIP in the regulation of death receptor-mediated apoptosis in pancreatic cancer was investigated.

METHODS

Expression of c-FLIP(L) and c-FLIP(S) was analysed in primary pancreatic carcinoma samples, pancreatic carcinoma cell lines and primary tumour cells together with its function as a regulator of death receptor-induced apoptosis by knockdown and overexpression studies and through modulation by chemotherapeutics.

RESULTS

c-FLIP is expressed in pancreatic intraepithelial neoplasm (PanIN) lesions and in pancreatic ductal adenocarcinomas, whereas normal pancreatic ducts were consistently negative for c-FLIP. Simultaneous downregulation of c-FLIP(L) and c-FLIP(S) as well as individual knockdown of either isoform by RNA interference significantly enhances TRAIL (tumour necrosis factor-related apoptosis-inducing ligand)- and CD95-induced caspase activation and caspase-dependent apoptosis. Also, pretreatment with chemotherapeutic drugs--that is, 5-fluorouracil (5-FU), cisplatin or gemcitabine--downregulates c-FLIP and renders cells sensitive to death receptor-triggered apoptosis. Similarly, primary cultured pancreatic cancer cells are primed for TRAIL-induced apoptosis by pre-exposure to 5-FU or cisplatin. Mechanistic studies revealed that 5-FU-mediated suppression of c-FLIP results in increased TRAIL-induced recruitment and activation of caspase-8 at the death-inducing signalling complex (DISC), leading to caspase-3 activation and caspase-dependent cell death. Overexpression of c-FLIP(L) rescues cells from 5-FU- or cisplatin-mediated sensitisation for TRAIL-induced apoptosis, indicating that c-FLIP suppression is a key event in this chemotherapy-mediated sensitisation to TRAIL. Further, concomitant neutralisation of c-FLIP and XIAP acts in concert to potentiate TRAIL-induced apoptosis.

CONCLUSIONS

Both the long and the short isoform of the antiapoptotic protein c-FLIP are critical regulators of death receptor-induced apoptosis in pancreatic carcinoma cells and are suppressed by chemotherapeutics. Targeting either c-FLIP(L) or c-FLIP(S) is sufficient to promote death receptor-induced apoptosis in pancreatic carcinoma cells. These findings have important implications for the design of TRAIL-based combination protocols in pancreatic cancer.

Dysregulation of autoimmunity caused by silica exposure and alteration of Fas-mediated apoptosis in T lymphocytes derived from silicosis patients

Silicosis patients suffer from pulmonary fibrosis caused by silica inhalation, as well as autoimmune diseases known as the adjuvant effects of silica. Caplan syndrome complicated with rheumatoid arthritis (RA) is well known epidemiologically, and the incidence of complicated systemic sclerosis (SSc), systemic lupus erythematosus (SLE) and antineutrophilic cytoplasmic antibody (ANCA)-related nephritis have been reported frequently in silicosis patients. To explore the detailed mechanisms of silica-induced dysregulation of autoimmunity, we had focused on Fas/CD95 and Fas-mediated apoptosis because Fas is one of the most important molecules regarding apoptosis of lymphocytes and its alteration makes some T cells survive longer. Additionally, if the long-survived T cells include the self-recognizing T-cell clones, it is easily thought that autoimmune diseases will appear in this situation. Furthermore, regulatory T cells (Treg) showing CD4+25+ and forkhead box P3 (FoxP3)-positive have been a central player in regulating activation of self- and foreign-antigen recognizing T cells, and it has been reported that activation of Treg causes its higher expression of Fas/CD95. Thus, in this review, we introduce the alteration of Fas and related molecules as found in silicosis and also present the Treg function of the CD4+25+ fraction in peripheral blood mononuclear cells derived from silicosis patients.

Upregulation of the pro-apoptotic genes BID and FAS in septic shock patients

INTRODUCTION

Lymphocyte apoptosis has been suggested to play a central role in sepsis pathophysiology, and studies in animal models demonstrated that blocking this pathway improves outcome. However, no routine biomarkers of apoptosis are so far available in patients. Thus, the aim of our study was to assess the different biomarkers of apoptosis putatively usable on a routine basis in septic shock.

METHODS

Thirteen septic shock patients (sampled twice between days 1 to 2 and days 3 to 5 after diagnosis of shock) and 15 sex-matched and age-matched healthy controls were prospectively enrolled. Apoptosis was measured in lymphocyte subpopulations using flow cytometry (Annexin-V binding, activated caspase-3 and Bcl-2 expressions). Representative pro-apoptotic and anti-apoptotic gene expressions were assessed by quantitative reverse-transcription PCR. Monocyte HLA-DR expression and lymphocyte subpopulation cell counts were measured as markers of sepsis-induced immune dysfunctions. To test for statistical significance, the Mann-Whitney U test was used with correction by the number of tests performed.

RESULTS

Flow cytometric measurements of apoptosis in septic shock patients showed an increased Annexin-V binding on CD4+ T cells and an increased active caspase-3 expression on B cells only at days 3 to 5 (sixfold change and twofold change, respectively). Gene expression analysis showed an increased BCL-XL mRNA and an upregulation of the pro-apoptotic genes BID and FAS in septic shock patients (10-fold change and fivefold change, respectively) compared with healthy controls.

CONCLUSIONS

The present study highlights the difficulties encountered in monitoring apoptosis on a routine basis in septic patients, whereas in the same sampling conditions and on the same patients, HLA-DR expression and lymphocyte subpopulation cell counts showed characteristics described in the literature. However, pro-apoptotic genes BID and FAS appear to constitute promising apoptosis markers in our hands.

[Alkylglycerolipids--modulators of tumor cells death]

The review is summarizes current information on biological activity and search of the antineoplastic mechanism of action of alkyl glycerolipids. Special attention is paid to following problems: selective ability phosphorus alkyl glycerolipids, antineoplastic activity, cytostatic and cytotoxic effects of edelfosine and its analogues. The review contains set of the data known for today from the literature, on the possible mechanism cytoyoxic actions of such connections.

Cisplatin augments FAS-mediated apoptosis through lipid rafts

Cisplatin is widely and effectively used for the treatment of various types of cancer. However, its biochemical mechanisms are still unelucidated. Previously, we reported that membrane sphingomyelin (SM) was important for FAS-mediated apoptosis through lipid raft function. In this study, we strikingly show that cisplatin combined with CH11 (anti-FAS antibody, IgM) was able to induce marked apoptosis in SM synthase-restored WR/Fas-SMS1 cells, but not in SM synthase-deficient WR/FAS-SM(-) cells. In addition, we demonstrated that membrane SM played an important role in cisplatin/CH11-induced apoptosis through the classical caspase-dependent pathway, mainly by enhancing the formation of FAS-associated signaling complexes.

Apoptotic effects of mahanine on human leukemic cells are mediated through crosstalk between Apo-1/Fas signaling and the Bid protein and via mitochondrial pathways

Apo-1 (Fas/CD95), a cell surface receptor, triggers apoptosis after binding to its physiological ligand, Apo-1L (FasL/CD95L). This study reports that mahanine, purified from the leaves of Murraya koenigii, has a dose- and time-dependent anti-proliferative activity in acute lymphoid (MOLT-3) and chronic myeloid (K562) leukemic cell lines and in the primary cells of leukemic and myeloid patients, with minimal effect on normal immune cells including CD34(+) cells. Leukemic cells underwent phosphatidylserine externalization and DNA fragmentation, indicating mahanine-induced apoptosis. An increase in reactive oxygen species suggests that the mahanine-induced apoptosis was mediated by oxidative stress. A significant drop in the Bcl2/Bax ratio, the loss of mitochondrial transmembrane potential as well as cytochrome c release from the mitochondria to the cytosol suggested involvement of the mitochondrial pathway of apoptosis. Cytochrome c release was followed by the activation of caspase-9, caspase-3 and caspase-7, and cleavage of PARP in both MOLT-3 and K562 cells. In MOLT-3 cells, formation of the Fas-FasL-FADD-caspase-8 heterotetramer occurred, leading to the cleavage of Bid to its truncated form, which consequently resulted in formation of the mitochondrial transmembrane pore. The incubation of MOLT-3 cells with mahanine in the presence of caspase-8 inhibitor or FasL-neutralizing NOK-2 antibody resulted in the decrease of mahanine-induced cell death. Mahanine was also a potent inhibitor of K562 xenograft growth, which was evident in an athymic nude mice model. In summary, these results provide evidence for involvement of the death receptor-mediated extrinsic pathway of apoptosis in the mahanine-induced anticancer activity in MOLT-3 cells, but not in K562 cells, which are deficient in Fas/FasL.

Progesterone stimulates mitochondrial activity with subsequent inhibition of apoptosis in MCF-10A benign breast epithelial cells

The effects of progesterone on breast epithelial cells remain poorly defined with observations showing both proliferative and antiproliferative effects. As an example, progesterone levels correlate with increased epithelial cell proliferation, but there is discordance between the dividing cells and the cells with nuclear progesterone receptor expression. The release of paracrine growth factors from nuclear receptor-positive cells has been postulated as a mechanism, since in vitro studies show a lack of growth effect by progesterone in breast epithelial cells lacking nuclear receptors. This study examined possible nongenomic effects of progesterone in breast epithelia by using MCF-10A cells known to lack nuclear progesterone receptor expression. Treatment for 30-60 min with progesterone or the progestin, R5020, increased mitochondrial activity as shown by an increase in mitochondrial membrane potential (hyperpolarization) with a concordant increase in total cellular ATP. The reaction was inhibited by a specific progesterone receptor antagonist and not affected by the translation inhibitor cycloheximide. Progestin treatment inhibited apoptosis induced by activation of the FasL pathway, as shown by a decrease in sub-G(1) cell fraction during fluorescence-activated cell sorting and a decrease in caspase 3/7 levels. Progestin treatment did not alter the cell cycle over 48 h. Our study demonstrates a nongenomic action of progesterone on benign breast epithelial cells, resulting in enhanced cellular respiration and protection from apoptosis.

Apoptosis and cancer: the genesis of a research field

In multicellular organisms, the total number of cells is a balance between the cell-generating effects of mitosis and cell death that is induced through apoptosis. A disruption of this delicate balance can lead to the development of cancer. This Timeline article focuses on how the field of apoptosis biology has developed in the context of its contribution to our understanding of cell death, or lack of it, in the development of malignant disease. It traces the course of research from key discoveries in fundamental biology to potential therapeutic applications.

[Receptor caspase-dependent and caspase-independent ways of human lymphocytes apoptosis induced by UV-radiation]

Changes of a structural condition of DNA, expression level of the membrane Fas-receptor and of functional activity of the human lymphocytes caspase-3 in dynamics of apoptosis development, induced by influence of UV-light (240-390 nm) in doses 151, 1510 and 3020 J/m2 are studied. It is established, that the UV-irradiation of lymphocytes in doses of 151 and 1510 J/m2 causes realisation of receptor caspase-dependent apoptosis way. The assumption about switching possibility of receptor caspase-dependent way apoptosis on receptor caspase-independent way at increase of a dose of UV-light to 3020 J/m2 is made.

Stat3-siRNA induces Fas-mediated apoptosis in vitro and in vivo in breast cancer

Stat3, a member of the signal transducer and activator of transcription family, has the potential to mediate cell survival, growth and differentiation. Stat3 is constitutively activated in numerous cancers, including >50% of breast cancers. Previous studies demonstrated that constitutively activated Stat3 plays an important role in breast cancer development and progression by promoting cell proliferation and inhibiting apoptosis. The present study was designed to investigate the potential use of RNA interference (RNAi) to block Stat3 expression and activation, as well as the subsequent effect on human breast cancer cell growth. Our studies show that knockdown of STAT3 expression by siRNA reduced expression of Bcl-xL and survivin in MDA-MB-231 cells, and also led to Fas mediated intrinsic apoptotic pathway by activating caspases -8, -9, -3 and PARP1 cleavage. In nude mice, pRNAi-Stat3 significantly suppressed tumor growth compared with controls. It also suppressed Stat3 expression, and downregulated BcL-xL and upregulated Fas, Fas-L and cleaved caspase-3 expression within the tumor, which significantly induced apoptosis and led to tumor suppression. Thus, targeting Stat3 signaling using siRNA may serve as a novel therapeutic strategy for the treatment of breast cancers expressing constitutively activated Stat3.

The role of MMP7 and its cross-talk with the FAS/FASL system during the acquisition of chemoresistance to oxaliplatin

Background

The efficacy of oxaliplatin in cancer chemotherapy is limited by the development of drug resistance. MMP7 has been related to the loss of tumor cell response to cytotoxic agents although the exact mechanism is not fully understood. Moreover, MMP7 is an independent prognosis factor for survival in patients with colorectal cancer. The aim of the present study was to analyze the role of MMP7 and its cross-talk with the Fas/FasL system during the acquisition of oxaliplatin resistance in colon cancer cells.

Principal Findings

For this purpose we have developed three different oxaliplatin-resistant cell lines (RHT29, RHCT116 p53^+/+, RHCT116 p53^−/−) from the parental HT29, HCT116 p53^+/+ and HCT116 p53^−/− colon cancer cells. MMP7 basal expression was higher in the resistant compared to the parental cell lines. MMP7 was also upregulated by oxaliplatin in both HT29 (p53 mutant) and RHCT116 p53^−/− but not in the RHCT116 p53^+/+. Inhibition of MMP by 1,10-phenantroline monohydrate or siRNA of MMP7 restores cell sensitivity to oxaliplatin-induced apoptosis in both HT29 and RHCT116 p53^−/− but not in the RHCT116 p53^+/+. Some of these effects are caused by alterations in Fas receptor. Fas is upregulated by oxaliplatin in colon cancer cells, however the RHT29 cells treated with oxaliplatin showed a 3.8-fold lower Fas expression at the cell surface than the HT29 cells. Decrease of Fas at the plasma membrane seems to be caused by MMP7 since its inhibition restores Fas levels. Moreover, functional analysis of Fas demonstrates that this receptor was less potent in inducing apoptosis in RHT29 cells and that its activation induces MAPK signaling in resistant cells.

Conclusions

Taking together, these results suggest that MMP7 is related to the acquisition of oxaliplatin-resistance and that its inhibition restores drug sensitivity by increasing Fas receptor. Furthermore, Fas undergoes a change in its functionality in oxaliplatin-resistant cells inducing survival pathways instead of apoptotic signals.

Human circulating CD4+CD25highFoxp3+ regulatory T cells kill autologous CD8+ but not CD4+ responder cells by Fas-mediated apoptosis

Mechanisms utilized by human regulatory T cells (Treg) for elimination of effector cells may vary. We investigated the possibility that the mechanism of Treg suppression depends on Fas/FasL-mediated apoptosis of responder cells (RC). CD4(+)CD25(high)Foxp3(+) Treg and autologous CD4(+)CD25(-) and CD8(+)CD25(-) subsets of RC were isolated from blood of 25 cancer patients and 15 normal controls and cocultured in the presence of OKT3 and IL-2 (150 or 1000 IU/ml). Suppression of RC proliferation was measured in CFSE assays. RC and Treg apoptosis was monitored by 7-aminoactinomycin D staining in flow-based cytotoxicity assays. Treg from all subjects expressed CD95(+), but only Treg from cancer patients expressed CD95L. These Treg, when activated via TCR plus IL-2, up-regulated CD95 and CD95L expression (p < 0.001) and suppressed CD8(+) RC proliferation (p < 0.001) by inducing Fas-mediated apoptosis. However, Treg cocultured with CD4(+) RC suppressed proliferation independently of Fas/FasL. In cocultures, Treg were found to be resistant to apoptosis in the presence of 1000 IU/ml IL-2, but at lower IL-2 concentrations (150 IU/ml) they became susceptible to RC-induced death. Thus, Treg and RC can reciprocally regulate Treg survival, depending on IL-2 concentrations present in cocultures. This divergent IL-2-dependent resistance or sensitivity of Treg and RC to apoptosis is amplified in patients with cancer.

Apoptotic mechanisms after cerebral ischemia

BACKGROUND AND PURPOSE

Traditionally, cell death after cerebral ischemia was considered to be exclusively necrotic in nature, but research over the past decade has revealed that after a stroke, many neurons in the ischemic penumbra will undergo apoptosis.

SUMMARY OF REVIEW

This brief review provides a general overview and update of various signaling pathways in the development of apoptosis in ischemic lesions. Cerebral ischemia triggers two general pathways of apoptosis: the intrinsic pathway, originating from mitochondrial release of cytochrome c and associated stimulation of caspase-3; and the extrinsic pathway, originating from the activation of cell surface death receptors, resulting in the stimulation of caspase-8. Although many of the key apoptotic proteins have been identified, our understanding of the complex underlying mechanisms remains poor and hence treatment of stroke patients by manipulating apoptotic pathways remains a daunting task. However, recent advances in the field have helped broaden our knowledge of apoptosis after cerebral ischemia. Further to the simplistic concept that stroke-induced apoptosis occurs predominantly in neurons and is caspase-dependent, accumulating evidence now indicates that apoptosis is prevalent in nonneuronal cells and that caspase-independent mechanisms also play a key role.

CONCLUSIONS

Although the ischemic penumbra is under threat of infarction, it is potentially salvageable and thus represents an opportunity for therapeutic intervention.

Lindane induces testicular apoptosis in adult Wistar rats through the involvement of Fas-FasL and mitochondria-dependent pathways

Lindane, an organochlorine pesticide, is known to impair testicular functions and fertility. To elucidate the mechanism(s) underpinning the gonadal effects of lindane, we sought to investigate the levels of apoptosis-related proteins, namely cytochrome c, caspase-3 and-9, Fas and FasL in the testis of adult rats. Furthermore, the study aims to delineate whether nuclear factor kappa B (NF-kappaB) is involved in meditating the testicular effects of lindane. Animals were administered with a single dose of lindane (5mg/kg body weight) and sacrificed at specific post-treatment intervals (0, 3, 6, 12, 24 and 72h). Significant elevations in the levels of cytosolic cytochrome c with a parallel increase in pro-caspase-9 were observed as early as 6h following exposure. Time-dependent elevations in the levels of Fas, FasL and caspase-3 were observed. Immunofluorescence studies revealed increased colocalization of Fas and caspase-3 in peritubular germ cells. FasL levels were increased in Sertoli and peritubular germ cells. The cytoplasmic levels of NF-kappaB p65 decreased from 3h following exposure with a maximal decline at 12 and 24h. Changes in the localization of NF-kappaB were observed with maximal nuclear translocation in germ cells at 12 and 24h. Terminal deoxynucleotidyl transferase-mediated dUTP nickend-labeling (TUNEL) assay revealed a time-dependent increase in the number of apoptotic cells. Taken together, the data illustrate induction of testicular apoptosis in adult rats following exposure to a single dose of lindane. Early activation of NF-kappaB in contrast to late increase in Fas expression suggests a pro-apoptotic role of NF-kappaB in testicular response to lindane.

Short-term versus long-term intermittent hypobaric hypoxia on cardiac fibrosis and Fas death receptor dependent apoptotic pathway in rat hearts

It is unknown if short-term and long-term intermittent hypobaric hypoxic challenges both exert pro-apoptotic effects on Fas death receptor-dependent apoptotic pathway in rat hearts. Seventy-two Sprague-Dawley rats were randomly assigned into two groups. First, short-term intermittent hypobaric hypoxia (STIHH)-normobaric normoxia (n = 12), hypobaric hypoxia (380 mmHg, 12% O2, 8 hrs/day) for 1 day (n = 12), and for 4 days (n = 12) and second, long-term intermittent hypobaric hypoxia (LTIHH)-normobaric normoxia (n = 12), hypobaric hypoxia for 1 week (n = 12) and 2 weeks (n = 12). After STIHH or LTIHH challenge, Fas receptor related pathway and histopathological analysis in the excised left ventricle was determined by Western blotting, RT-PCR, Hematoxylin-eosin staining, Masson trichrome staining and TUNEL assay. Fas death receptor and TNFalpha were significantly decreased after STIHH whereas Fas receptor, TNFalpha, FAS-associated death domain (FADD), and caspase 8 were increased after LTIHH. In addition, cardiomyocyte disarray and fibrosis were observed in 1 week LTIHH. Cardiac hypertrophy and more severe disarray, fibrosis and cardiac apoptotic activities were observed in 2 week LTIHH. STIHH exerts anti-apoptotic effects on hearts such as downregulation of TNFalpha and Fas receptor whereas LTIHH exerts pro-apoptotic effects such as upregulation of TNFalpha and Fas-mediated apoptotic pathways and lead to cardiac fibrosis and apoptosis. Our findings imply that short-term versus long-term intermittent hypobaric hypoxia exerted protective versus deleterious effects on hearts.

Cultured murine thyroid epithelial cells expressing transgenic Fas-associated death domain-like interleukin-1beta converting enzyme inhibitory protein are protected from fas-mediated apoptosis

The antiapoptotic molecule Fas-associated death domain-like IL-1beta-converting enzyme inhibitory protein (FLIP) inhibits Fas-mediated apoptosis by blocking activation of caspase-8. We previously showed that expression of transgenic FLIP on thyroid epithelial cells (TECs) of DBA/1 and CBA/J mice promoted earlier resolution of granulomatous experimental autoimmune thyroiditis in vivo. This study was undertaken to directly determine whether transgenic FLIP expressed on cultured TECs can protect TECs from Fas-mediated apoptosis in vitro. The results indicate that cultured TECs from DBA/1 and CBA/J mice can be sensitized in vitro by interferon-gamma and TNF-alpha to undergo Fas-mediated apoptosis. Transgenic overexpression of FLIP protected cultured TECs of FLIP transgene (Tg)+ DBA/1 and CBA/J mice from Fas-mediated apoptosis, and FLIP small interfering RNA transfection of cultured TECs of FLIP Tg+ DBA/1 and CBA/J mice abolished the protective effect. These in vitro results are consistent with our previous in vivo studies using DBA/1 and CBA/J FLIP Tg+ mice and provide direct support for the hypothesis that transgenic expression of FLIP promotes resolution of granulomatous experimental autoimmune thyroiditis by protecting TECs from apoptosis.

Activation of the mitochondria-driven pathway of apoptosis in human PC-3 prostate cancer cells by a novel hydrophilic paclitaxel derivative, 7-xylosyl-10-deacetylpaclitaxel

Paclitaxel, a natural product originally isolated from Taxus brevifolia, belongs to the most successful anticancer drugs. Nevertheless, its poor water solubility represents a considerable disadvantage in clinical use, and novel derivatives with improved pharmacological features are required. We isolated 7-xylosyl-10-deacetylpaclitaxel from Taxus chinensis, which reveals higher water solubility than paclitaxel. This compound induced mitotic cell cycle arrest and apoptosis as measured by flow cytometry, DNA laddering, and transmission electron microscopy. Pro-apoptotic Bax and Bad protein expression was up-regulated and anti-apoptotic Bcl-2 and Bcl-XL expression down-regulated, which lead to a disturbance of the mitochondrial membrane permeability and to the activation of caspase-9. In turn, caspase-9 activated downstream caspases-3 and -6, but not caspase-8. Bid was also activated by caspase-3. Reversely, treatment with a caspase-10-specific inhibitor could not protect PC-3 cells from 7-xylosyl-10-deacetyl-paclitaxel-triggered apoptosis. Moreover, 7-xylosyl-10-deacetylpaclitaxel had no effect on the expression of CD95 and NF-kappaB proteins, indicating that apoptosis was induced through the mitochondrial-dependent pathway in PC-3 cells.

Beta cells in type 2 diabetes - a crucial contribution to pathogenesis

The healthy beta-cell has an enormous capacity to adapt to conditions of higher insulin demand (e.g. in obesity, pregnancy, cortisol excess) to maintain normoglycaemia with an increase in its functional beta-cell mass. This compensates in 80-90% of individuals for insulin resistance. However, in 10-20% of individuals, the beta-cells are unable to match the demands of insulin resistance and insulin levels are relatively insufficient to maintain normal glycaemic control. This eventually leads to glucose intolerance and type 2 diabetes (T2DM). Accordingly, preservation of functional beta-cell mass has become central in the treatment of type 1 diabetes as well as T2DM. The purpose of this review is to summarize the recently described mechanisms of beta-cell death in T2DM and to postulate possible new targets for treatment.

Epidermal growth factor receptor inhibitors enhance susceptibility to Fas-mediated apoptosis in oral squamous cell carcinoma cells

Molecular inhibition of epidermal growth factor receptor (EGFR) signaling is a promising cancer treatment strategy. We examined whether inhibition of EGFR signaling would affect the susceptibility of oral squamous cell carcinoma (OSCC) cells to Fas-mediated apoptosis. Treatment of OSCC cells with an anti-EGFR monoclonal antibody, C225, and an EGFR tyrosine kinase inhibitor, AG1478, which target the extracellular and intracellular domains of the receptor, respectively, inhibited phosphorylation of EGFR and its downstream effector molecule Akt and amplified the induction of Fas-mediated apoptosis. In OSCC cells treated with EGFR inhibitors, Fas-mediated apoptosis was accompanied by caspase-8 activation but not Bid cleavage. Caspase-3 and -8 inhibitors reduced the effect of EGFR inhibitors on Fas-mediated apoptosis in OSCC cells, but a caspase-9 inhibitor did not. These results indicate that the pro-apoptotic activity of EGFR inhibitors in OSCC cells depends on the extrinsic pathway of the caspase cascade. Although EGFR inhibitors did not affect the expression of Fas, the Fas-associated death domain protein, or procaspase-8 in OSCC cells, the inhibition downregulated cellular FLICE-inhibitory protein (c-FLIP). Moreover, knockdown of c-FLIP in HSC-2 cells with a small interfering RNA strongly enhanced Fas-mediated apoptosis. These results suggest that the EGFR signaling pathway may, in part, regulate Fas-mediated apoptosis in OSCC cells through c-FLIP expression.

Mechanism of action of l-CDB-4022, a potential nonhormonal male contraceptive, in the seminiferous epithelium of the rat testis

The present study was conducted to elucidate the possible molecular mechanisms involved in the antispermatogenic activity of l-CDB-4022, an indenopyridine. In this study 45-d-old male Sprague-Dawley rats were treated with a single oral dose of l-CDB-4022 (2.5 mg/kg) or vehicle, and blood and testes were collected at various time points. The rate of body weight gain was not affected, but a significant loss of testes weight was induced by l-CDB-4022. Serum hormones were assayed using specific RIAs or ELISAs, and testicular protein and RNA were analyzed by Western blotting and RT-PCR, respectively. There was a significant decrease in inhibin B and concomitant increase in FSH in serum from l-CDB-4022-treated rats, but serum levels of activin A, testosterone, and LH were unchanged. Western analysis of testicular lysates from l-CDB-4022-treated rats exhibited phosphorylation of ERK1/2 at 4 h and later time points. Loss of nectin/afadin complex occurred at 48 h, but there was an increase in levels of integrin-beta1, N-cadherin, alpha-catenin, and beta-catenin protein at 24 h and later time points. Increase in expression of Fas ligand and Fas receptor was detected 8 and 24 h after l-CDB-4022 treatment. The ratio of the membrane to soluble form of stem cell factor mRNA was decreased. Immunohistochemical analysis of testicular sections indicated a dramatic disruption of the Sertoli cell microtubule network in l-CDB-4022-treated rats. Collectively, these results suggest that l-CDB-4022 activates the MAPK pathway, reduces expression of prosurvival factors such as the membrane form of stem cell factor, alters expression of Sertoli-germ cell adherens junction proteins, disrupts Sertoli cell microtubule structure, and induces the proapoptotic factor, Fas, culminating in germ cell loss from the seminiferous epithelium.