Expression of the inhibitor of apoptosis (IAP) family members in human neutrophils: up-regulation of cIAP2 by granulocyte colony-stimulating factor and overexpression of cIAP2 in chronic neutrophilic leukemia

Expression of Forkhead Box M1 and Anticancer Effects of FOXM1 Inhibition in Epithelioid Sarcoma

Epithelioid sarcoma (ES) is a rare aggressive sarcoma that, unlike most soft-tissue sarcomas, shows a tendency toward local recurrence and lymph node metastasis. Novel antitumor agents are needed for ES patients. Forkhead box transcription factor 1 (FOXM1) is a member of the Forkhead transcription factor family and is associated with multiple oncogenic functions; FOXM1 is known to be overexpressed and correlated with pathogenesis in various malignancies. In this study, we immunohistochemically analyzed FOXM1 expression levels and their clinical, clinicopathologic, and prognostic significance in 38 ES specimens. In addition, to investigate potential correlations between FOXM1 downregulation and oncologic characteristics, we treated ES cell lines with thiostrepton, a naturally occurring antibiotic that inhibits both small interfering RNA (siRNA) and FOXM1. In the analyses using ES samples, all 38 specimens were diagnosed as positive for FOXM1 by immunohistochemistry. We separated specimens into high (n = 19) and low (n = 19) FOXM1-protein expression groups by staining index score, and into large (n = 12), small (n = 25), and unknown (n = 1) tumor-size groups using a cutoff of 5 cm maximum diameter. Although there were significantly more samples with high FOXM1 expression in the large tumor group (P = .013), there were no significant differences with respect to age (P = 1.00), sex (P = .51), primary site of origin (P = .74), histologic subtypes (P = 1.00), depth (P = .74), or survival rate (P = .288) between the high and low FOXM1-protein expression groups. In the in vitro experiments using ES cell lines, FOXM1 siRNA and thiostrepton successfully downregulated FOXM1 mRNA and protein expression. Furthermore, downregulation of FOXM1 inhibited cell proliferation, drug resistance against chemotherapeutic agents, migration, and invasion and caused cell cycle arrest in the ES cell lines. Finally, cDNA microarray analysis data showed that FOXM1 regulated cIAP2, which is one of the apoptosis inhibitors activated by the TNFα-mediated NF-κB pathway. In conclusion, the FOXM1 gene may be a promising therapeutic target for ES.

The Role of miR-29a and miR-143 on the Anti-apoptotic MCL-1/cIAP-2 Genes Expression in EGFR Mutated Non-small Cell Lung Carcinoma Patients

The survival rate of lung cancer is low due to the high frequency of drug resistance in patients with mutations in the driver genes. Overexpression of anti-apoptotic genes is one of the most prominent features of tumor drug resistance. EGFR signaling induces the expression of anti-apoptotic genes. Also, microRNAs (miRNAs) have a critical role in regulating biological functions such as apoptosis; a process mostly eluded in cancer progression. The mutation screening was performed on one thousand non-small cell lung carcinoma patients to enroll clinical samples in this study. Bioinformatics analysis predicted that miRNAs (miR-29a, miR-143) might regulate MCL-1 and cIAP-2 expression. We investigated the expression of MCL-1, cIAP-2, miR-29a, and miR-143 encoding genes in adenocarcinoma patients with or without EGFR mutations before treatment. The potential role of miR-29a and miR-143 on gene expression was evaluated by overexpression and luciferase assays in HEK-293T cells. EGFR mutations were found in 262 patients (26.2%) with a greater incidence in females (36.23% vs. 20.37%, P = 0.001). The expression levels of MCL-1 and cIAP-2 genes in patients with mutated EGFR were higher than those of wild-type EGFR. In contrast, compared to those of patients with wild-type EGFR, the expression levels of miR-29a and miR-143 were lower in the patients carrying EGFR mutations. In cell culture, overexpression of miR-29a and miR-143 significantly downregulated the expression of MCL-1 and cIAP-2. Dual-luciferase reporter experiments confirmed that miR-29a and miR-143 target MCL-1 and cIAP-2 mRNAs, respectively. Our results suggest that upregulation of EGFR signaling in lung cancer cells may increase anti-apoptotic MCL-1 and cIAP-2 gene expression, possibly through downregulation of miR-29a-3p and miR-143-3p.

STAT3 protects dopaminergic neurons against degeneration in animal model of Parkinson's disease

INTRODUCTION

Parkinson's disease (PD) is the most prevalent disorder of the basal ganglia, propagated by the degeneration of axon terminals within the striatum and subsequent loss of dopaminergic neurons in the substantia nigra (SN). Exposure of environmental neurotoxins and mutations of several mitochondrial and proteasomal genes are primarily responsible.

METHODS

To determine whether signal transducer and activator of transcription 3 (STAT3) could protect dopaminergic neurons against degeneration, we first screened it in the in vitro capacity using immortalized rat dopaminergic N27 cells under 6-OHDA neurotoxicity. We then evaluated the effectiveness of constitutively active (ca) STAT3 as a neuroprotective agent on N27 cells in a 6-hydroxydopamine (6-OHDA) induced rat model of PD and compared it to control animals or animals where AAV/caRheb was expressed in SN. Behavioral outcomes were assessed using rotational and cylinder assays and mitochondrial function using reactive oxygen species (ROS) levels.

RESULTS

Using flow cytometry, the in vitro analysis determined caSTAT3 significantly decreased dopaminergic neuronal death under 6-OHDA treatment conditions. Importantly, in vivo overexpression of caSTAT3 in SN dopaminergic neurons using AAV-mediated expression demonstrated significant neuroprotection of dopaminergic neurons following 6-OHDA. Both caSTAT3 and caRheb + caSTAT3 co-injection into substantia nigra reduced D-amphetamine-induced rotational behavior and increased ipsilateral forelimb function when compared to control animals. In addition, caSTAT3 decreased mitochondrial ROS production following 6-OHDA induced neurotoxicity.

CONCLUSION

caSTAT3 confers resistance against ROS production in mitochondria of susceptible SN dopaminergic neurons potentially offering a new avenue for treatment against PD.

Targeting Upregulated cIAP2 in SOX10-Deficient Drug Tolerant Melanoma

Drug tolerance and minimal residual disease (MRD) are likely to prelude acquired resistance to targeted therapy. Mechanisms that allow persister cells to survive in the presence of targeted therapy are being characterized but selective vulnerabilities for these subpopulations remain uncertain. We identified cellular inhibitor of apoptosis protein 2 (cIAP2) as being highly expressed in SOX10-deficient drug tolerant persister (DTP) melanoma cells. Here, we show that cIAP2 is sufficient to induce tolerance to MEK inhibitors, likely by decreasing the levels of cell death. Mechanistically, cIAP2 is upregulated at the transcript level in SOX10-deficient cells and the AP-1 complex protein, JUND, is required for its expression. Using a patient-derived xenograft model, we demonstrate that treatment with the cIAP1/2 inhibitor, birinapant, during the MRD phase delays the onset of resistance to BRAF inhibitor and MEK inhibitor combination therapy. Together, our data suggest that cIAP2 upregulation in SOX10-deficient subpopulations of melanoma cells induces drug tolerance to MAPK targeting agents and provides a rationale to test a novel therapeutical approach to target MRD.

Apoptotic cell death in disease-Current understanding of the NCCD 2023

Apoptosis is a form of regulated cell death (RCD) that involves proteases of the caspase family. Pharmacological and genetic strategies that experimentally inhibit or delay apoptosis in mammalian systems have elucidated the key contribution of this process not only to (post-)embryonic development and adult tissue homeostasis, but also to the etiology of multiple human disorders. Consistent with this notion, while defects in the molecular machinery for apoptotic cell death impair organismal development and promote oncogenesis, the unwarranted activation of apoptosis promotes cell loss and tissue damage in the context of various neurological, cardiovascular, renal, hepatic, infectious, neoplastic and inflammatory conditions. Here, the Nomenclature Committee on Cell Death (NCCD) gathered to critically summarize an abundant pre-clinical literature mechanistically linking the core apoptotic apparatus to organismal homeostasis in the context of disease.

Pharmacological Induction of Granulocyte Cell Death as Therapeutic Strategy

Apoptosis is central for the maintenance of health. In the immune system, apoptosis guarantees proper development of immune cells and shutdown of immune reactions by the coordinated elimination of activated immune cells. Limitation of the life span of granulocytes is important, as overactivation of these cells is associated with chronic inflammation and collateral tissue damage. Consequently, targeted induction of granulocyte apoptosis may be beneficial in the course of respective immune disorders. Anti-inflammatory drugs such as glucocorticoids and monoclonal antibodies against IL-5Rα exert their function in part by triggering eosinophil apoptosis. Agonistic antibodies targeting Siglec-8 or death receptors are tested (pre)clinically. Moreover, a new class of inhibitors targeting antiapoptotic BCL-2 proteins shows great promise for anticancer treatments. Because of their specificity and tolerable side effects, these so-called BH3 mimetics may be worthwhile to evaluate in inflammatory disorders. Here, we review past and recent data on pharmacological apoptosis induction of granulocytes and highlight respective therapeutic potential.

Molecular Mechanisms for Regulation of Neutrophil Apoptosis under Normal and Pathological Conditions

Neutrophils are one of the main cells of innate immunity that perform a key effector and regulatory function in the development of the human inflammatory response. Apoptotic forms of neutrophils are important for regulating the intensity of inflammation and restoring tissue homeostasis. This review summarizes current data on the molecular mechanisms of modulation of neutrophil apoptosis by the main regulatory factors of the inflammatory response-cytokines, integrins, and structural components of bacteria. Disturbances in neutrophil apoptosis under stress are also considered, molecular markers of changes in neutrophil lifespan associated with various diseases and pathological conditions are presented, and data on pharmacological agents for modulating apoptosis as potential therapeutics are also discussed.

Expression and Correlation of Cell-Free cIAP-1 and cIAP-2 mRNA in Breast Cancer Patients: A Study from India

Background

Inhibitors of apoptosis proteins such as cIAP-1 and cIAP-2 have recently emerged as the key mechanism in resistance to apoptosis in various cancers and lead to cell survival. Therefore, the present study aimed to evaluate the cIAP-1 and cIAP-2 expression in breast cancer patients, as well as their association with overall patient survival.

Methods

Histopathologically confirmed 100 invasive ductal carcinoma patients and healthy controls were included in the present study. Total RNA extraction was done from the serum sample of the patients; further, 100 ng of total RNA was used to synthesise cDNA from patients' as well as from healthy controls' serum. Quantitative real-time PCR was performed using the maxima SYBR Green dye to study the expression of cIAP-1 and cIAP-2, and beta-actin was used as the internal control.

Results

The study observed that breast cancer patients had 13.50 mean fold increased cIAP-1 mRNA and 8.76 mean fold increased cIAP-2 mRNA expression compared to the control subjects. Breast cancer patients in the TNM stages I, II, III, and IV showed 9.54, 11.80, 15.19, and 16.83 mean fold increased cIAP-1 mRNA expression (p=0.004). Distant organ metastasis, (p=0.008), PR status of breast cancer patients (p < 0.0001), and HER2 status of breast cancer patients (p < 0.0001) were found to be associated with cIAP-1 mRNA expression. Breast cancer patients with different TNM stages such as stages I, II, III, and IV showed 7.8, 8.09, 7.97, and 12.85 mean fold increased cIAP-2 mRNA expression (p=0.0002). Breast cancer patients with distant organ metastases status were found to be associated with cIAP-2 mRNA expression (p < 0.0001). Breast cancer patients with <13-fold and >13-fold cIAP-1 mRNA expression showed 37.39 months and 34.70 months of overall median survival, and the difference among them was found to be significant (p=0.0001). However, cIAP-2 mRNA expression among <8-fold and >8-fold mRNA expression groups showed 35 months and 27.90 months of overall median survival time (p < 0.0001). Higher cIAP-1 mRNA expression was linked with smoking and alcoholism among the breast cancer patients (p < 0.0001 and p < 0.0001). Significant association of higher cIAP-1 mRNA expression was found with the advancement of the disease, while higher mRNA expression of cIAP-1 was associated with distant organ metastases in ROC curve analysis.

Conclusion

The present study suggested that increased cell-free cIAP-1 and cIAP-2 mRNA expression was correlated with the advancement of disease, progression of disease, and overall reduced patient survival. Cell-free cIAP-1 and cIAP-2 mRNA expression could be the predictive indicator of the disease.

Identification of key protein-coding genes and lncRNAs in spontaneous neutrophil apoptosis

Polymorphonuclear leukocytes (PMNs) are the most abundant cells of the innate immune system in humans, and spontaneous PMN apoptosis plays crucial roles in maintaining neutrophil homeostasis and resolving inflammation. However, the detailed mechanisms of spontaneous PMN apoptosis remain to be elucidated. By analysis of the public microarray dataset GSE37416, we identified a total of 3050 mRNAs and 220 long non-coding RNAs (lncRNAs) specifically expressed during PMN apoptosis in a time-dependent manner. By short time-series expression miner (STEM) analysis, Gene Ontology analysis, and lncRNA-mRNA co-expression network analyses, we identified some key molecules specifically related to PMN apoptosis. STEM analysis identified 12 gene profiles with statistically significance, including 2 associated with apoptosis. Protein-protein interaction (PPI) network analysis of the genes from 2 profiles and lncRNA-mRNA co-expression network analysis identified a 12-gene hub (including NFκB1 and BIRC3) associated with apoptosis, as well as 2 highly correlated lncRNAs (THAP9-AS1, and AL021707.6). We experimentally examined the expression profiles of two mRNA (NFκB1 and BIRC3) and two lncRNAs (THAP9-AS1 andAL021707.6) by quantitative real-time polymerase chain reaction to confirm their time-dependent expressions. These data altogether demonstrated that these genes are involved in the regulation of spontaneous neutrophil apoptosis and the corresponding gene products could also serve as potential key regulatory molecules for PMN apoptosis and/or therapeutic targets for over-reactive inflammatory response caused by the abnormality in PMN apoptosis.

Nickel chloride-induced apoptosis via mitochondria- and Fas-mediated caspase-dependent pathways in broiler chickens

Ni, a metal with industrial and commercial uses, poses a serious hazard to human and animal health. In the present study, we used flow cytometry, immunohistochemistry and qRT-PCR to investigate the mechanisms of NiCl₂-induced apoptosis in kidney cells. After treating 280 broiler chickens with 0, 300, 600 or 900 mg/kg NiCl₂ for 42 days, we found that two caspase-dependent pathways were involved in the induced renal tubular cell apoptosis. In the mitochondria-mediated caspase-dependent apoptotic pathway, cyt-c, HtrA2/Omi, Smac/Diablo, apaf-1, PARP, and caspase-9, 3, 6 and 7 were all increased, while. XIAP transcription was decreased. Concurrently, in the Fas-mediated caspase-dependent apoptotic pathway, Fas, FasL, caspase-8, caspase-10 and Bid levels were all increased. These results indicate that dietary NiCl₂ at 300+ mg/kg induces renal tubular cell apoptosis in broiler chickens, involving both mitochondrial and Fas-mediated caspase-dependent apoptotic pathways. Our results provide novel insight into Ni and Ni-compound toxicology evaluated in vitro and in vivo.

cIAP2 promotes gallbladder cancer invasion and lymphangiogenesis by activating the NF-κB pathway

Several studies have produced contradictory findings about the prognostic implications for inhibitor of apoptosis proteins (IAP) in different types of cancer. Cellular inhibitor of apoptosis 2 (cIAP2/BIRC) is one of the most extensively characterized human IAP. To date, no studies have focused on the expression level of cIAP2 in human gallbladder cancer (GBC), and the mechanism of cIAP2 in GBC invasion and lymphangiogenesis remains unclear. Therefore, in the present study, cIAP2 expression in GBC was detected using quantitative real‐time polymerase chain reaction and immunohistochemistry, and the relationship between cIAP2 levels in cancer tissues and the clinicopathological characteristics of patients was analyzed. The biological effect of cIAP2 in GBC cells was tested using the Cell Counting Kit‐8 Assay, Transwell assays and the ability of human dermal lymphatic endothelial cells (HDLEC) to undergo tube formation. The role of cIAP2 in activating the NF‐κB pathway was determined using a dual‐luciferase reporter assay, immunofluorescence staining, western blotting and ELISA. Finally, an animal model was used to further confirm the role of cIAP2 in lymphangiogenesis. We showed that cIAP2 expression was elevated in human GBC tissues and correlated with a negative prognosis for patients. Moreover, cIAP2 was identified as a lymphangiogenic factor of GBC cells and, thus, promoted lymph node metastasis in GBC cells. Our study is the first to suggest that cIAP2 can promote GBC invasion and lymphangiogenesis by activating the NF‐κB pathway.

The Role of cIAP1 and XIAP in Apoptosis Induced by Tumor Necrosis Factor Alpha in Esophageal Squamous Cell Carcinoma Cells

BACKGROUND

The inhibitor of apoptosis protein (IAP) family are reported to play important roles in cancer cells evading apoptosis. However, the significance of their expression in human esophageal squamous cell carcinoma (ESCC) cells remains uncertain.

AIMS

The present study aimed to investigate the role of the IAP family members in tumor necrosis factor-α (TNF-α)-induced apoptosis of human ESCC cells.

METHODS

Five human ESCC cell lines were pretreated with TNF-α, cycloheximide (CHX, protein synthesis inhibitor), epoxomicin (proteasome inhibitor). Apoptosis assay and protein study with Western blot testing were conducted. Knockdown experiments with IAP siRNA were conducted, and the effect on cell apoptosis was analyzed.

RESULTS

Significant apoptosis was induced in five ESCC cell lines by TNF-α plus CHX stimulation, but not when treated with TNF-α or CHX alone. The protein expression levels of cIAP1 and XIAP were decreased by treatment with TNF-α in the presence of CHX, and the degree of cIAP1 and XIAP expression decrease was correlated with sensitivity to TNF-α plus CHX-induced apoptosis. Epoxomicin suppressed TNF-α plus CHX-induced degradation of survivin, cIAP1, and XIAP, in addition to apoptosis. A caspase inhibitor (z-VAD-fmk) suppressed TNF-α plus CHX-induced apoptosis, but did not suppress degradation of survivin, cIAP1, and XIAP. Furthermore, cIAP1 or XIAP siRNA transfected cells underwent apoptosis in response to treatment with TNF-α alone. Double knockdown of both genes resulted in further increased apoptosis.

CONCLUSION

cIAP1 and XIAP play an essential role in the resistance of ESCC cells against apoptosis.

Research Advances on Pathways of Nickel-Induced Apoptosis

High concentrations of nickel (Ni) are harmful to humans and animals. Ni targets a number of organs and produces multiple toxic effects. Apoptosis is important in Ni-induced toxicity of the kidneys, liver, nerves, and immune system. Apoptotic pathways mediated by reactive oxygen species (ROS), mitochondria, endoplasmic reticulum (ER), Fas, and c-Myc participate in Ni-induced cell apoptosis. However, the exact mechanism of apoptosis caused by Ni is still unclear. Understanding the mechanism of Ni-induced apoptosis may help in designing measures to prevent Ni toxicity.

Tumor necrosis factor-α-induced apoptosis of gastric cancer MKN28 cells: accelerated degradation of the inhibitor of apoptosis family members

The role of the inhibitor of apoptosis (IAP) family members in tumor necrosis factor-α (TNF-α)-induced apoptosis of human gastric cancer MKN28 cells was explored. TNF-α induced up-regulation of cIAP2, whereas cycloheximide (CHX) induced down-regulation of XIAP and survivin. Degradation of cIAP1 and XIAP, but not survivin, was accelerated by co-treatment of cells with TNF-α and CHX, and TNF-α-induced up-regulation of cIAP2 was inhibited by BMS-345541 (NF-κB inhibitor). Treatment of MKN28 cells with TNF-α plus CHX induced degradation of survivin and activation of caspase-8 and -3, followed by degradation of cIAP1 and XIAP and apoptosis. Proteasome inhibitors (MG132 and epoxomicin) suppressed TNF-α plus CHX-induced degradation of survivin, cIAP1, and XIAP as well as apoptosis. A caspase inhibitor (z-VAD-fmk) suppressed TNF-α plus CHX-induced apoptosis, but allowed degradation of survivin, cIAP1 and XIAP. TNF-α receptor 1 and 2 were expressed on MKN28 cells. The magnitude of apoptosis induced by TNF-α plus BMS-345541 was much less than that induced by TNF-α plus CHX. These findings suggest that TNF-α plus CHX-induced apoptosis of gastric cancer MKN28 cells may be caused by accelerated degradation of the IAP family members (survivin, cIAP1, and XIAP), in addition to inhibition of NF-κB-dependent synthesis of anti-apoptotic molecules.

Assessment of neutrophil apoptosis

Timely neutrophil apoptosis and cell clearance by surrounding phagocytes are essential components of the resolution phase of acute inflammation. Programmed cell death by apoptosis occurs with maintenance of an intact cell membrane in order to prevent the release of histotoxic intracellular products such as proteases and reactive oxidant species into the extracellular surroundings as occurs during necrosis. Macrophage phagocytosis results in attenuation of toll-like receptor-driven proinflammatory mediator production further promoting inflammation resolution. Failures in this cascade of events can result in tissue damage, chronic inflammation and disease. By studying human neutrophil apoptosis and phagocytic clearance in vitro, it is possible to delineate key control mechanisms in the regulation of these processes and therefore also identify potential therapeutic targets. Apoptotic signalling pathways are well described in the literature using a variety of laboratory techniques. In this paper, we outline the key in vitro assays used to assess neutrophil apoptosis, activation of key components of the apoptotic machinery, and phagocytic clearance of these cells.

Gender difference in tumor necrosis factor-α production in human neutrophils stimulated by lipopolysaccharide and interferon-γ

The gender difference in tumor necrosis factor-α (TNF-α) production in human neutrophils stimulated by lipopolysaccharide (LPS) and interferon-γ (IFN-γ) was explored by using peripheral blood neutrophils from young men and women. As compared with female neutrophils, male neutrophils released greater amounts of TNF-α, and exhibited stronger activation of mitogen-activated protein kinases and phosphatidylinositol 3-kinase in response to LPS stimulation. LPS-induced TNF-α production was markedly enhanced by pretreatment of cells with IFN-γ, and IFN-γ-mediated priming in male neutrophils was significantly greater than that in female neutrophils. Male neutrophils showed higher expression of TLR4, but not IFN-γ receptors, than female neutrophils, and its expression was increased by stimulation with IFN-γ or IFN-γ plus LPS. These findings indicate that male neutrophils show higher responsiveness to stimulation with LPS and IFN-γ than female neutrophils, and suggest that the gender difference in neutrophil responsiveness to LPS and IFN-γ is partly responsible for that in the outcome of sepsis, in which premenopausal women show a favorable prognosis as compared with men.

Mechanisms regulating neutrophil survival and cell death

Neutrophils not only play a critical role as a first line of defense against bacteria and fungi infections but also contribute to tissue injury associated with autoimmune and inflammatory diseases. Neutrophils are rapidly and massively recruited from the circulation into injured tissues displaying an impressive arsenal of toxic weapons. Although effective in their ability to kill pathogens, these weapons were equally effective to induce tissue damage. Therefore, the inflammatory activity of neutrophils must be regulated with exquisite precision and timing, a task mainly achieved through a complex network of mechanisms, which regulate neutrophil survival. Neutrophils have the shortest lifespan among leukocytes and usually die via apoptosis although new forms of cell death have been characterized over the last few years. The lifespan of neutrophils can be dramatically modulated by a large variety of agents such as cytokines, pathogens, danger-associated molecular patterns as well as by pharmacological manipulation. Recent findings shed light about the complex mechanisms responsible for the regulation of neutrophil survival in different physiological, pathological, and pharmacological scenarios. Here, we provide an updated review on the current knowledge and new findings in this field and discuss novel strategies that could be used to drive the resolution of neutrophil-mediated inflammatory diseases.

Prevention of methamphetamine-induced microglial cell death by TNF-α and IL-6 through activation of the JAK-STAT pathway

Background

It is well known that methamphetamine (METH) is neurotoxic and recent studies have suggested the involvement of neuroinflammatory processes in brain dysfunction induced by misuse of this drug. Indeed, glial cells seem to be activated in response to METH, but its effects on microglial cells are not fully understood. Moreover, it has been shown that cytokines, which are normally released by activated microglia, may have a dual role in response to brain injury. This led us to study the toxic effect of METH on microglial cells by looking to cell death and alterations of tumor necrosis factor-alpha (TNF-α) and interleukine-6 (IL-6) systems, as well as the role played by these cytokines.

Methods

We used the N9 microglial cell line, and cell death and proliferation were evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling assay and incorporation of bromodeoxyuridine, respectively. The TNF-α and IL-6 content was quantified by enzyme-linked immunosorbent assay, and changes in TNF receptor 1, IL-6 receptor-alpha, Bax and Bcl-2 protein levels by western blotting. Immunocytochemistry analysis was also performed to evaluate alterations in microglial morphology and in the protein expression of phospho-signal transducer and activator of transcription 3 (pSTAT3).

Results

METH induced microglial cell death in a concentration-dependent manner (EC₅₀ = 1 mM), and also led to significant morphological changes and decreased cell proliferation. Additionally, this drug increased TNF-α extracellular and intracellular levels, as well as its receptor protein levels at 1 h, whereas IL-6 and its receptor levels were increased at 24 h post-exposure. However, the endogenous proinflammatory cytokines did not contribute to METH-induced microglial cell death. On the other hand, exogenous low concentrations of TNF-α or IL-6 had a protective effect. Interestingly, we also verified that the anti-apoptotic role of TNF-α was mediated by activation of IL-6 signaling, specifically the janus kinase (JAK)-STAT3 pathway, which in turn induced down-regulation of the Bax/Bcl-2 ratio.

Conclusions

These findings show that TNF-α and IL-6 have a protective role against METH-induced microglial cell death via the IL-6 receptor, specifically through activation of the JAK-STAT3 pathway, with consequent changes in pro- and anti-apoptotic proteins.

Maintenance of surface antigens and the absence of an apoptotic marker are observed during storage of granulocyte concentrates collected by bag separation method

Granulocytes were collected by the bag separation method and stored in whole blood for up to 72h. We evaluated the expressions of various surface antigens: CD62L, CD11b, CD18, CD64, CD16b, and CD95. Apoptosis was assessed both by flow cytometry and by light microscopy. Expression levels of all the surface antigens were shown to be maintained during storage for up to 72h. Approximately 80% of granulocytes were annexin V negative until 72h after collection. The storage of granulocyte concentrates collected by the bag separation method may maintain granulocyte surface antigens and lack an apoptotic marker.

Co-expression of XIAP and cyclin D1 complex correlates with a poor prognosis in patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the world. Despite improved diagnosis and treatment, the prognosis for HCC patients remains poor. The goal of this study was to identify key regulatory proteins and signaling pathways important for cell apoptosis and proliferation as biomarkers for prognostication and targeted therapy. Protein Pathway Array was applied to screen 38 signaling proteins and phosphoproteins in 12 paired HCC tumors and surrounding benign tissues and found that 20 of them, including XIAP, CDK4, CDK6, and Cyclin D1, were overexpressed in HCC tissues. Immunostaining results of XIAP, CDK4, and Cyclin D1 in an additional 59 HCC tissues showed that the expression of XIAP correlated with the expression of CDK4/Cyclin D1, and that the increased expression of these proteins correlated with poor overall survival in these patients. Further studies using the HCC Huh7 cell line transfected with XIAP siRNA or expression vector demonstrated that XIAP regulated the expression of CDK4, CDK6, and Cyclin D1 via NF-êB and PTEN pathways. Finally, inhibition of XIAP using embelin, a XIAP-specific small molecule, leads to an increased apoptosis and decreased cell proliferation via arrest at G1 phase. Taken together, XIAP is a central modulator regulating cell apoptosis and cell cycle progression. Therefore, XIAP together with cell cycle regulatory proteins can be used as prognostic markers and therapeutic targets.

Decreased neutrophil apoptosis in quiescent ANCA-associated systemic vasculitis

Background

ANCA-Associated Systemic Vasculitis (AASV) is characterized by leukocytoclasis, accumulation of unscavenged apoptotic and necrotic neutrophils in perivascular tissues. Dysregulation of neutrophil cell death may contribute directly to the pathogenesis of AASV.

Methods

Neutrophils from Healthy Blood Donors (HBD), patients with AASV most in complete remission, Polycythemia Vera (PV), Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA) and renal transplant recipients (TP) were incubated in vitro, and the rate of spontaneous apoptosis was measured by FACS. Plasma levels of cytokines and sFAS were measured with cytometric bead array and ELISA. Expression of pro/anti-apoptotic factors, transcription factors C/EBP-α, C/EBP-β and PU.1 and inhibitors of survival/JAK2-pathway were measured by real-time-PCR.

Results

AASV, PV and RA neutrophils had a significantly lower rate of apoptosis compared to HBD neutrophils (AASV 50±14% vs. HBD 64±11%, p<0.0001). In RA but not in AASV and PV, low apoptosis rate correlated with increased plasma levels of GM-CSF and high mRNA levels of anti-apoptotic factors Bcl-2A1 and Mcl-1. AASV patients had normal levels of G-CSF, GM-CSF and IL-3. Both C/EBP-α, C/EBP-β were significantly higher in neutrophils from AASV patients than HBD. Levels of sFAS were significantly higher in AASV compared to HBD.

Conclusion

Neutrophil apoptosis rates in vitro are decreased in AASV, RA and PV but mechanisms seem to differ. Increased mRNA levels of granulopoiesis-associated transcription factors and increased levels of sFAS in plasma were observed in AASV. Additional studies are required to define the mechanisms behind the decreased apoptosis rates, and possible connections with accumulation of dying neutrophils in regions of vascular lesions in AASV patients.

Impact of uremic environment on peritoneum: a proteomic view

Peritoneal morphology and function are abnormal in uremia patients, but the contributing mechanisms are unclear. Here we attempted to characterize the protein targets that may be related to peritoneal change in patients with uremia and have not exposed to peritoneal dialysis fluid. Protein profiles of peritoneal fluids collected from patients with uremia and patients with normal renal function receiving laparoscopic cholecystectomy were displayed by two-dimensional gel electrophoresis (2-DE). Altered protein spots were excised and subjected to tryptic digestion followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Sixteen 2-DE protein spots were altered between two groups. Western blots confirmed that kininogen-1, apoptosis inhibitor 2, cat eye syndrome critical region protein 1, and apolipoprotein A-I had higher expression levels in the uremia samples. In contrast, synaptic vesicle 2-related protein, glial fibrillary acidic protein, and envelope glycoprotein (C2-V5 region) showed lower levels. The increased expression may result from a change in the permeability of the peritoneal membrane to middle-sized proteins or peritoneal inflammation with proteins sloughing off. All the identified proteins may provide a novel understanding of peritoneal changes caused by uremic toxins and may function as biomarkers or drug targets.

Exploiting inhibitor of apoptosis proteins as therapeutic targets in hematological malignancies

Resistance to apoptosis is one of the hallmarks of human cancers and contributes to the insensitivity of many cancers to commonly used treatment approaches. Inhibitor of apoptosis (IAP) proteins, a family of anti-apoptotic proteins, have an important role in evasion of apoptosis, as they can both block apoptosis-signaling pathways and promote survival. High expression of IAP proteins is observed in multiple cancers, including hematological malignancies, and has been associated with unfavorable prognosis and poor patients' outcome. Therefore, IAP proteins are currently considered as promising molecular targets for therapy. Indeed, drug-discovery approaches over the last decade aiming at neutralizing IAP proteins have resulted in the generation of small-molecule inhibitors or antisense oligonucleotides that demonstrated in vitro and in vivo antitumor activities in preclinical studies. As some of these strategies have already entered the stage of clinical evaluation, for example, in leukemia, an update on this promising molecular-targeted strategy to interfere with apoptotic pathways is of broad interest.

Human papillomavirus-16 (HPV-16) infection association with CIAP-2 expression in head and neck cancer

Human papillomavirus (HPV-16) E6 proteins inhibit apoptosis in both p53-dependent and p53-independent manners. So it was relevant to assess the impact of such infection on head and neck cancers and its relation to the inhibitors of apoptosis (IAPs). CIAP2 is one of these IAPs that is postulated to upregulated by E6 proteins of HPV-16 by amplification of the locus bearing it in many tissues. In this study, we aimed to search for the amplification of the locus bearing CIAP-2 and its relation to HPV-16 in head and neck cancer that may have prognostic and therapeutic impacts on these patients. Total 30 patients diagnosed as head and neck cancer (2 tissue samples were taken from each patient: from the tumor and from the safety margin). All samples were subjected to qualitative polymerase chain reaction analysis for HPV-16 and qualitative and semiquantitative reverse transcription polymerase chain reaction of CIAP-2. There was a significant association between HPV-16 and CIAP2 positivity and head and neck tumors (P=0.01). CIAP-2 expression in malignant tissues was highly associated with HPV-16 infection with 73.9% sensitivity and absolute specificity.

Peculiarities of cell death mechanisms in neutrophils

Analyses of neutrophil death mechanisms have revealed many similarities with other cell types; however, a few important molecular features make these cells unique executors of cell death mechanisms. For instance, in order to fight invading pathogens, neutrophils possess a potent machinery to produce reactive oxygen species (ROS), the phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Evidence is emerging that these ROS are crucial in the execution of most neutrophil cell death mechanisms. Likewise, neutrophils exhibit many diverse granules that are packed with cytotoxic mediators. Of those, cathepsins were recently shown to activate pro-apoptotic B-cell lymphoma-2 (Bcl-2) family members and caspases, thus acting on apoptosis regulators. Moreover, neutrophils have few mitochondria, which hardly participate in ATP synthesis, as neutrophils gain energy from glycolysis. In spite of relatively low levels of cytochrome c in these cells, the mitochondrial death pathway is functional. In addition to these pecularities defining neutrophil death pathways, neutrophils are terminally differentiated cells, hence they do not divide but undergo apoptosis shortly after maturation. The initial trigger of this spontaneous apoptosis remains to be determined, but may result from low transcription and translation activities in mature neutrophils. Due to the unique biological characteristics of neutrophils, pharmacological intervention of inflammation has revealed unexpected and sometimes disappointing results when neutrophils were among the prime target cells during therapy. In this study, we review the current and emerging models of neutrophil cell death mechanisms with a focus on neutrophil peculiarities.

NF-kappaB protects human papillomavirus type 38 E6/E7-immortalized human keratinocytes against tumor necrosis factor alpha and UV-mediated apoptosis

Constitutive activation of NF-κB signaling is a key event in virus- and non-virus-induced carcinogenesis. We have previously reported that cutaneous human papillomavirus type 38 (HPV38) displays transforming properties in in vitro and in vivo experimental models. However, the involvement of NF-κB signaling in HPV38-induced cell growth transformation remains to be determined. In this study, we showed that HPV38 E6 and E7 activate NF-κB and that inhibition of the pathway with the IκBα superrepressor sensitizes HPV38E6E7-immortalized human keratinocytes to tumor necrosis factor alpha (TNF-α)- and UVB radiation-mediated apoptosis. Accordingly, inhibition of NF-κB signaling resulted in the downregulation of NF-κB-regulated antiapoptotic genes, including cIAP1, cIAP2, and xIAP genes. These findings demonstrate a critical role of NF-κB activity in the survival of HPV38E6E7-immortalized human keratinocytes exposed to cytokine or UV radiation. Our data provide additional evidence for cooperation between beta HPV infection and UV irradiation in skin carcinogenesis.

The molecular mechanisms of glucocorticoids-mediated neutrophil survival

Neutrophil-dominated inflammation plays an important role in many airway diseases including asthma, chronic obstructive pulmonary disease (COPD), bronchiolitis and cystic fibrosis. In cases of asthma where neutrophil-dominated inflammation is a major contributing factor to the disease, treatment with corticosteroids can be problematic as corticosteroids have been shown to promote neutrophil survival which, in turn, accentuates neutrophilic inflammation. In light of such cases, novel targeted medications must be developed that could control neutrophilic inflammation while still maintaining their antibacterial/anti-fungal properties, thus allowing individuals to maintain effective innate immune responses to invading pathogens. The aim of this review is to describe the molecular mechanisms of neutrophil apoptosis and how these pathways are modulated by glucocorticoids. These new findings are of potential clinical value and provide further insight into treatment of neutrophilic inflammation in lung disease.

Bortezomib synergizes TRAIL-induced apoptosis in gastric cancer cells

Background/Aims Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as a newly identified biological agent has shown promising antitumor effects in a wide range of cancers. However, gastric cancer cells are less sensitive than other cancer cells to TRAIL-induced apoptosis.Here, we combined TRAIL with bortezomib, a proteasomal inhibitor to induce apoptosis in three gastric cancer cell lines.Methods After the cells were treated with TRAIL and/or bortezomib, the cell viability, apoptosis and cell cycle distribution were examined. The levels of death receptors and the mitochondrial membrane potential were also detected. The expression of apoptosis-associated proteins was determined by Western blot.Results Bortezomib at low concentration significantly(P<0.05) enhanced the cytotoxic effect of TRAIL by enhancing apoptosis as well as cell cycle arrest at G2/M phase. The enhancement of efficiency of TRAIL by bortezomib involved up-regulation of death receptor 4 and 5, as well as reduction of the mitochondrial membrane potential. Further study showed that combined treatment with TRAIL and bortezomib down-regulated anti-apoptotic protein cIAP-1, and over expression of cIAP-1 significantly(P\0.05) reduced the synergistic effect between TRAIL and bortezomib.Conclusions Bortezomib synergizes TRAIL-induced apoptosis in human gastric cancer cells. The synergistic effect between these two drugs is associated with up-regulation of death receptors and down-regulation of cIAP-1.The combination of TRAIL and bortezomib might be an effective regimen for the treatment of advanced gastric cancer.

Differential expression of factors involved in the intrinsic and extrinsic apoptotic pathways in juvenile systemic lupus erythematosus

Dysregulated neutrophil apoptosis may result in the development of autoimmune disease by contributing to nuclear autoantigen exposure, leading to autoantibody generation and a breakdown in immune tolerance. It has previously been shown that neutrophil apoptosis is increased in juvenile-onset systemic lupus erythematosus (JSLE). This study aims to investigate the pathways involved in JSLE serum-induced apoptosis. Caspases 3, 7–9, IAP1/2, XIAP and FADD mRNA levels and TRAIL R2, BID/tBID, caspase 8 and 9 protein expression were measured in neutrophils from JSLE patients ( n = 14) and controls ( n = 10). The mRNA levels of caspases 7–9 were significantly higher in JSLE neutrophils than in controls, whereas the mRNA levels of IAP1, IAP2 and XIAP were decreased ( p < 0.05). A decrease in neutrophil apoptosis induced by JSLE serum was observed in the presence of caspase 8 and 9 inhibitors ( p < 0.05), and the activity of caspases 8 and 9 increased over time. tBID protein expression increased following incubation with JSLE serum. These data focus specifically on the expression and activity of the main caspases in the intrinsic and extrinsic apoptotic pathways. Increased expression of factors involved in the downstream signalling of the extrinsic apoptotic pathway indicates a prominent involvement of this pathway in JSLE serum-induced apoptosis.

New insights into the mechanisms controlling neutrophil survival

PURPOSE OF REVIEW

Neutrophil survival is regulated by a complex convergence of different pathways. The present review analyzes these pathways and discusses how neutrophil survival is modulated during the course of inflammatory reactions.

RECENT FINDINGS

Although apoptosis appears to be the predominant cell death pathway in the neutrophil, recent data reveal that neutrophil survival is also regulated by a number of nonconventional pathways including NETosis, autophagic cell death, and other less characterized mechanisms. This supports an even more complex picture of the mechanisms involved in the regulation of neutrophil survival than previously thought.

SUMMARY

The control of neutrophil survival is central to homoeostasis and resolution of inflammation. Cell death is usually discussed dichotomously in terms of apoptosis or necrosis. There are two main pathways responsible for the stimulation of apoptosis; a death receptor pathway triggered by Fas, tumor necrosis factor alpha, and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and a mitochondrial pathway stimulated by a number of stressors such as DNA damage, growth factor deprivation, and chemotherapy drugs. Nonconventional pathways of neutrophil death include NETosis and autophagic cell death as well as a number of poorly characterized mechanisms. Understanding the integrated pathways responsible for the control of neutrophil survival holds therapeutic promise in infectious and inflammatory diseases.

Granulocyte colony-stimulating factor negatively regulates Toll-like receptor agonist-induced cytokine production in human neutrophils

We studied the effect of G-CSF on TLR agonist-induced cytokine production in human neutrophils. Human neutrophils produced IL-8 and TNF-alpha in response to stimulation with TLR agonists such as LPS and N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-(R)-cysteinyl-seryl-(lysyl)(3)-lysine. This response was dependent on activation of ERK, p38, and PI3K, but not JNK. TLR agonist-induced cytokine production in neutrophils was inhibited by G-CSF, whereas it was enhanced by GM-CSF, and GM-CSF-mediated enhancement was attenuated by G-CSF. G-CSF and GM-CSF did not affect TLR agonist-induced phosphorylation of ERK, p38, JNK, Akt, and IkappaBalpha. STAT3 activation was much greater in G-CSF-stimulated neutrophils than that in GM-CSF-stimulated cells. G-CSF-mediated STAT3 phosphorylation and inhibition of TLR agonist-induced cytokine production were prevented by pretreatment of cells with AG-490 (JAK2 inhibitor). These findings suggest that G-CSF and GM-CSF exert the opposite effects on TLR agonist-induced cytokine production, and G-CSF negatively regulates TLR agonist-induced cytokine production in neutrophils via activation of STAT3.

LIM domain only 4 protein promotes granulocyte colony-stimulating factor-induced signaling in neurons

Granulocyte colony-stimulating factor (GCSF) is currently in clinical trials to treat neurodegenerative diseases and stroke. Here, we tested whether LIM domain only 4 protein (LMO4), a hypoxia-inducible gene that protects neurons from ischemic injury, could modulate the neuroprotective effect of GCSF. We showed that GCSF treatment acetylates and phosphorylates Stat3, activates expression of a Stat3-dependent anti-apoptotic gene, p27, and increases neuron survival from ischemic injury. LMO4 participates in Stat3 signaling in hepatocytes and associates with histone deacetylase 2 (HDAC2) in cancer cells. In the absence of LMO4, GCSF fails to rescue neurons from ischemic insults. In wild-type neurons, inhibition of HDAC promoted Stat3 acetylation and the antiapoptotic effect of GCSF. In LMO4 null cortical neurons, expression of wild-type but not HDAC-interaction-deficient LMO4 restored GCSF-induced Stat3 acetylation and p27 expression. Thus, our results indicate that LMO4 enhances GCSF-induced Stat3 signaling in neurons, in part by sequestering HDAC.

Effect of progesterone on gonococci-induced apoptosis and respiratory burst of human polymorphonuclear leukocytes in vitro

BACKGROUND

Progesterone may have clinical relevance in females with asymptomatic gonococcal infections.

AIM

To investigate the regulatory effect of progesterone on apoptosis and oxidative burst activity of polymorphonuclear leukocytes (PMNs) challenged by Neisseria gonorrhoeae in vitro.

METHODS

Isolated PMNs were incubated with progesterone or staurosporine. Staurosporine was used as a positive control for our in vitro model. Expression levels of inhibitory apoptosis proteins (IAPs), cellular IAP2 (cIAP2), and X-linked IAP (XIAP) were determined by real-time polymerase chain reaction (PCR). In addition, PMN apoptosis at various time points (3, 8, 12, and 24 h) was assayed by flow cytometry. Luminol amplified chemiluminescence methods were used to quantify the oxidative burst function of PMNs challenged with N. gonorrhoeae ST2951.

RESULTS

cIAP2 was upregulated significantly in PMNs with progesterone treatment in 3 h, and XIAP was upregulated slightly compared with the medium + ST2951 group, whereas cIAP2 was downregulated in staurosporine-challenged PMNs. In addition, we found that progesterone delayed the onset of apoptosis activity in N. gonorrhoeae ST2951-challenged PMNs, notably at 12 h. No statistically significant changes in PMN oxidative burst activity were observed at 10 ng/mL of progesterone. Staurosporine enhanced the production of superoxide anion (respiratory burst) of human PMNs stimulated by N. gonorrhoeae.

CONCLUSION

Progesterone plays an important regulatory role in the interaction of PMNs and N. gonorrhoeae. Delayed PMN apoptosis induced by progesterone presumably acts as a mechanism for N. gonorrhoeae to avoid the innate immune response and establish long-term, low-level infection in the female reproductive tract.

Enhancement of TRAIL cytotoxicity by AG-490 in human ALL cells is characterized by downregulation of cIAP-1 and cIAP-2 through inhibition of Jak2/Stat3

The ability of death-inducing tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to selectively kill a variety of cancer cells has been largely described, but one of the major concerns with the treatment is the occurrence of drug resistance and possible toxic side effects. Here, we report that TRAIL induces apoptosis in Jurkat and SUPT1 T cell lines and in human T-ALL blasts but not in healthy subject-derived peripheral blood mononuclear cells. In parallel, the treatment with TRAIL and Tyrphostin (AG-490), a selective Janus kinase 2 inhibitor, produces an evident enhancement of cytotoxicity, characterized by a significant inhibition of Stat3 phosphorylation compared to controls or to TRAIL alone-treated samples, and associated with a dramatic decrease of both cIAP-1 and cIAP-2 mRNA levels. Downregulation of cIAP-1 and cIAP-2 by specific small interference RNAs significantly amplifies TRAIL-reduced cytotoxicity. All together, these findings strongly indicate that cIAP-1 and cIAP-2 downregulation is a fundamental step in the signaling pathways mediating the combinatorial effect of TRAIL and AG-490 on T cell leukemia. These findings may help to open new routes for the development of less toxic pharmacological strategies in the treatment of patients affected by TRAIL-sensitive leukemias.

Role of signal transducer and activator of transcription 3 in neuronal survival and regeneration

Signal Transducers and Activators of Transcription (STATs) comprise a family of transcription factors that mediate a wide variety of biological functions in the central and peripheral nervous systems. Injury to neural tissue induces STAT activation, and STATs are increasingly recognized for their role in neuronal survival. In this review, we discuss the role of STAT3 during neural development and following ischemic and traumatic injury in brain, spinal cord and peripheral nerves. We focus on STAT3 because of the expanding body of literature that investigates protective and regenerative effects of growth factors, hormones and cytokines that use STAT3 to mediate their effect, in part through transcriptional upregulation of neuroprotective and neurotrophic genes. Defining the endogenous molecular mechanisms that lead to neuroprotection by STAT3 after injury might identify novel therapeutic targets against acute neural tissue damage as well as chronic neurodegenerative disorders.

MMP13, Birc2 (cIAP1), and Birc3 (cIAP2), amplified on chromosome 9, collaborate with p53 deficiency in mouse osteosarcoma progression

Osteosarcoma is the primary malignant cancer of bone and particularly affects adolescents and young adults, causing debilitation and sometimes death. As a model for human osteosarcoma, we have been studying p53(+/-) mice, which develop osteosarcoma at high frequency. To discover genes that cooperate with p53 deficiency in osteosarcoma formation, we have integrated array comparative genomic hybridization, microarray expression analyses in mouse and human osteosarcomas, and functional assays. In this study, we found seven frequent regions of copy number gain and loss in the mouse p53(+/-) osteosarcomas but have focused on a recurrent amplification event on mouse chromosome 9A1. This amplicon is syntenic with a similar chromosome 11q22 amplicon identified in several human tumor types. Three genes on this amplicon, the matrix metalloproteinase gene MMP13 and the antiapoptotic genes Birc2 (cIAP1) and Birc3 (cIAP2), show elevated expression in mouse and human osteosarcomas. We developed a functional assay using clonal osteosarcoma cell lines transduced with lentiviral short hairpin RNA vectors to show that down-regulation of MMP13, Birc2, or Birc3 resulted in reduced tumor growth when transplanted into immunodeficient recipient mice. These experiments revealed that high MMP13 expression enhances osteosarcoma cell survival and that Birc2 and Birc3 also enhance cell survival but only in osteosarcoma cells with the chromosome 9A1 amplicon. We conclude that the antiapoptotic genes Birc2 and Birc3 are potential oncogenic drivers in the chromosome 9A1 amplicon.

Granulocyte-colony stimulating factor inhibits neuronal apoptosis in a rat model of diabetic cerebral ischemia

Incidence of cerebral vascular disease (CVD) is higher in patients with diabetes mellitus (DM) than that in individuals without DM, and neuronal apoptosis determines the severity of cerebral infarction. However, there is no effective therapy for CVD. Granulocyte-colony stimulating factor (G-CSF), a potent hematopoietic factor, could inhibit apoptosis of hematopoietic progenitor cells. However, its effect on neuronal cells is still unclear. In this study, we investigated the anti-apoptosis properties of G-CSF in neurons following focal cerebral ischemia in diabetic rats. The diabetic condition was generated in rats by intravenous injection of streptozotocin. After 6 weeks, diabetic rats underwent middle cerebral artery occlusion (MCAO) and received subcutaneous administration of G-CSF (50 microg/kg) daily for 7, 14 or 21 days. We analyzed the changes in neurological severity scores, infarct volume, number of apoptotic neurons, and the expression of G-CSF receptor, phosphorylated signal transducer and activator of transcription 3 (pSTAT3), cellular inhibitor of apoptosis protein 2 (cIAP2), Bcl-2, and Bax in the brain tissue. Bax is a pro-apoptotic member of the Bcl-2 protein family. The DM rats treated with G-CSF not only showed the reduced infarct volume and decreased apoptosis cell number, but also presented improved neurological scores. The G-CSF also increased the expression of pSTAT3, Bcl-2, and cIAP2 proteins as well as Bcl-2 mRNA, but inhibited Bax protein expression in the brain. These results indicate that G-CSF partially increases neuronal survival by affecting apoptosis pathways. G-CSF provides a potential treatment for stroke and other neurological dysfunction accompanied by neuronal apoptosis.

Inhibitor of apoptosis proteins in hematological malignancies

Apoptosis or programmed cell death is a key mechanism to control tissue homeostasis, for example, in the hematopoietic system. Thus, resistance to apoptosis can contribute to the development of leukemia or lymphoma. Inhibitors of apoptosis (IAP) proteins block cell death pathways at a central node by interfering with the activation of effector caspases. As increased expression levels of IAPs are found in hematological malignancies and have been correlated with poor prognosis, IAPs could be exploited as therapeutic targets and prognostic markers. Various strategies have been developed to target IAPs for therapeutic purposes in leukemia and lymphoma cells, including small-molecule inhibitors and antisense oligonucleotides. These agents could directly induce apoptosis in malignant cells or sensitize these cells to other cytotoxic agents. Thus, IAPs present promising targets for the development of new biomarkers and cancer therapeutics in hematological malignancies.

Characteristics of transplanted mouse myeloproliferative disease developed after repeated injections of granulocytic colony-stimulating factor

Transplanted myeloproliferative disease developed in mice against the background of repeated injections of granulocytic CSF was characterized using morphological and molecular biological methods. It was demonstrated that transplanted myeloproliferative disease had a non-viral nature and is probably induced by repeated injections of granulocytic CSF. Tumor cells actively populate the liver of sick animals, which leads to their rapid death. Expression of Myc, Abl, G-CSF, and MPO genes is enhanced, which is typical of myeloid neoplastic transformation.

Distinct role of c-Jun N-terminal kinase isoforms in human neutrophil apoptosis regulated by tumor necrosis factor-alpha and granulocyte-macrophage colony-stimulating factor

We studied the role of c-Jun N-terminal kinase (JNK) in human neutrophils stimulated by tumor necrosis factor-alpha (TNF-alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF). Stimulation of neutrophils with TNF-alpha and GM-CSF caused phosphorylation of p54 or p46 JNK or both. The phosphorylated p46 JNK band in TNF-alpha-stimulated neutrophils mobilized faster than that in GM-CSF-stimulated cells. The JNK isoform transcripts expressed in neutrophils were JNK1beta1, JNK1beta2, JNK2alpha1, and JNK2alpha2. The JNK isoforms phosphorylated by TNF-alpha and GM-CSF stimulation were found to be JNK1 and JNK2, respectively, on the basis of the molecular mass and the capture assay. TNF-alpha-induced JNK phosphorylation was sustained in the presence of cycloheximide, which was accompanied by accelerated neutrophil apoptosis. The JNK inhibitors (SP600125 and TAT-TI-JIP(153163)) suppressed neutrophil apoptosis induced by TNF-alpha plus cycloheximide, whereas they attenuated the GM-CSF-mediated antiapoptotic effect on neutrophils. The JNK inhibitor did not affect the levels of Mcl-1 and XIAP (antiapoptotic molecules), which were regulated by TNF-alpha plus cycloheximide and GM-CSF. The JNK inhibitor markedly suppressed TNF-alpha-induced and GM-CSF-induced superoxide release. These findings suggest that JNK1 and JNK2 are involved in TNF-alpha-induced neutrophil apoptosis and GM-CSF-mediated antiapoptotic effect on neutrophils, respectively, and both JNK isoforms are involved in TNF-alpha-induced and GM-CSF-induced superoxide release.

IL-3 induces a Pim1-dependent antiapoptotic pathway in primary human basophils

The contribution of basophils in allergic disease and other Th2-type immune responses depends on their persistence at sites of inflammation, but the ligands and molecular pathways supporting basophil survival are largely unknown. The comparison of rates of apoptosis and of the expression of antiapoptotic proteins in different human granulocyte types revealed that basophils have a considerably longer spontaneous life span than neutrophils and eosinophils consistent with high levels of constitutive Bcl-2 expression. Interleukin-3 (IL-3) is the only ligand that efficiently protects basophils from apoptosis as evidenced by screening a large number of stimuli. IL-3 up-regulates the expression of the antiapoptotic proteins cIAP2, Mcl-1, and Bcl-X(L) and induces a rapid and sustained de novo expression of the serine/threonine kinase Pim1 that closely correlates with cytokine-enhanced survival. Inhibitor studies and protein transduction of primary basophils using wild-type and kinase-dead Pim1-Tat fusion-proteins demonstrate the functional importance of Pim1 induction in the IL-3-enhanced survival. Our data further indicate that the antiapoptotic Pim1-mediated pathway operates independently of PI3-kinase but involves the activation of p38 MAPK. The induction of Pim1 leading to PI3-kinase-independent survival as described here for basophils may also be a relevant antiapoptotic mechanism in other terminally differentiated leukocyte types.

Calpain inhibition delays neutrophil apoptosis via cyclic AMP-independent activation of protein kinase A and protein kinase A-mediated stabilization of Mcl-1 and X-linked inhibitor of apoptosis (XIAP)

Human neutrophils underwent spontaneous apoptosis, which was accompanied with proteasome-mediated degradation of Mcl-1 and X-linked inhibitor of apoptosis (XIAP). Calpain inhibitors (PD150606 and N-acetyl-Leu-Leu-Nle-CHO) prevented spontaneous neutrophil apoptosis and degradation of Mcl-1 and XIAP, and the effects of calpain inhibitors on neutrophils were resistant to cycloheximide. Calpain inhibitors induced protein kinase A (PKA) activation, which was unaccompanied with an increase in intracellular cyclic AMP. Calpain inhibition-mediated delayed neutrophil apoptosis, stabilization of Mcl-1 and XIAP, and phosphorylation of PKA substrates were suppressed by H-89 (specific PKA inhibitor). These findings suggest that calpain inhibition delays neutrophil apoptosis via cyclic AMP-independent activation of PKA and PKA-mediated stabilization of Mcl-1 and XIAP.

Transmembrane TNF-alpha mediates "forward" and "reverse" signaling, inducing cell death or survival via the NF-kappaB pathway in Raji Burkitt lymphoma cells

Interestingly, some lymphoma cells, expressing high levels of transmembrane (tm)TNF-alpha, are resistant to secretory (s)TNF-alpha-induced necrosis but sensitive to tmTNF-alpha-mediated apoptosis. As tmTNF-alpha mediates "forward" as well as "reverse" signaling, we hypothesize that a balanced signaling between forward and reverse directions may play a critical role in determining the fate of cells bearing tmTNF-alpha. Using Raji cells as a model, we first added exogenous tmTNF-alpha on fixed, transfected NIH3T3 cells onto Raji cells to examine tmTNF-alpha forward signaling and its effects, showing that constitutive NF-kappaB activity and cellular inhibitor-of-apoptosis protein 1 transcription were down-regulated, paralleled with Raji cell death. As Raji cells express tmTNF-alpha, an inhibition of their tmTNF-alpha expression by antisense oligonucleotide caused down-regulation of NF-kappaB activity. Conversely, increasing tmTNF-alpha expression by suppressing expression of TNF-alpha-converting enzyme that cleaves tmTNF-alpha led to an enhanced activation of NF-kappaB, indicating that tmTNF-alpha, but not sTNF-alpha, contributes to constitutive NF-kappaB activation. We next transfected Raji cells with a mutant tmTNF-alpha lacking the intracellular domain to competitively suppress reverse signaling via tmTNF-alpha; as expected, constitutive NF-kappaB activity was decreased. In contrast, treating Raji cells with sTNFR2 to stimulate reverse signaling via tmTNF-alpha enhanced NF-kappaB activation. We conclude that tmTNF-alpha, when highly expressed on tumor cells and acting as a receptor, promotes NF-kappaB activation through reverse signaling, which is helpful to maintain tumor cell survival. On the contrary, tmTNF-alpha, when acting as a ligand, inhibits NF-kappaB activity through forward signaling, which is inclined to induce tumor cell death.