Regulating the balance between necroptosis, apoptosis and inflammation by inhibitors of apoptosis proteins

Spatial proteomics identifies JAKi as treatment for a lethal skin disease

Toxic epidermal necrolysis (TEN) is a fatal drug-induced skin reaction triggered by common medications and is an emerging public health issue1-3. Patients with TEN undergo severe and sudden epidermal detachment caused by keratinocyte cell death. Although molecular mechanisms that drive keratinocyte cell death have been proposed, the main drivers remain unknown, and there is no effective therapy for TEN4-6. Here, to systematically map molecular changes that are associated with TEN and identify potential druggable targets, we utilized deep visual proteomics, which provides single-cell-based, cell-type-resolution proteomics7,8. We analysed formalin-fixed, paraffin-embedded archived skin tissue biopsies of three types of cutaneous drug reactions with varying severity and quantified more than 5,000 proteins in keratinocytes and skin-infiltrating immune cells. This revealed a marked enrichment of type I and type II interferon signatures in the immune cell and keratinocyte compartment of patients with TEN, as well as phosphorylated STAT1 activation. Targeted inhibition with the pan-JAK inhibitor tofacitinib in vitro reduced keratinocyte-directed cytotoxicity. In vivo oral administration of tofacitinib, baricitinib or the JAK1-specific inhibitors abrocitinib or upadacitinib ameliorated clinical and histological disease severity in two distinct mouse models of TEN. Crucially, treatment with JAK inhibitors (JAKi) was safe and associated with rapid cutaneous re-epithelialization and recovery in seven patients with TEN. This study uncovers the JAK/STAT and interferon signalling pathways as key pathogenic drivers of TEN and demonstrates the potential of targeted JAKi as a curative therapy.

The Evolution and Biological Activity of Metazoan Mixed Lineage Kinase Domain-Like Protein (MLKL)

In mammals, mixed lineage kinase domain-like protein (MLKL) is the executor of necroptosis. MLKL comprises an N-terminal domain (NTD), which alone suffices to trigger necroptosis by forming pores in the plasma membrane, and a C-terminal domain that inhibits the NTD activity. Evolutionarily, MLKL is poorly conserved in animals and not found in Protostomia. Although MLKL orthologs exist in invertebrate Deuterostomia, the biological activity of invertebrate MLKL is unknown. Herein, we examined 34 metazoan phyla and detected MLKL not only in Deuterostomia but also in Protostomia (Rotifera). The Rotifera MLKL exhibited low identities with non-Rotifera MLKL but shared relatively high identities with non-metazoan MLKL. In invertebrates, MLKL formed two phylogenetic clades, one of which was represented by Rotifera. In vertebrates, MLKL expression was tissue-specific and generally rich in immune organs. When expressed in human cells, the MLKL-NTD of Rotifera, Echinodermata, Urochordata, and Cephalochordata induced strong necroptosis. The necroptotic activity of Rotifera MLKL depended on a number of conserved residues. Together these findings provided new insights into the evolution of MLKL in Metazoa and revealed the biological activity of invertebrate MLKL.

E3 ubiquitin ligase gene BIRC3 modulates TNF-induced cell death pathways and promotes aberrant proliferation in rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by synovitis, degradation of articular cartilage, and bone destruction. Fibroblast-like synoviocytes (FLS) play a central role in RA, producing a significant amount of inflammatory mediators such as tumor necrosis factor(TNF)-α and IL-6, which promote inflammatory responses within the joints. Moreover, FLS exhibit tumor-like behavior, including aggressive proliferation and enhanced anti-apoptotic capabilities, which collectively drive chronic inflammation and joint damage in RA. TNF is a major pro-inflammatory cytokine that mediates a series of signaling pathways through its receptor TNFR1, including NF-κB and MAPK pathways, which are crucial for inflammation and cell survival in RA. The abnormal proliferation and anti-apoptotic characteristics of FLS in RA may result from dysregulation in TNF-mediated cell death pathways such as apoptosis and necroptosis. Ubiquitination is a critical post-translational modification regulating these signaling pathways. E3 ubiquitin ligases, such as cIAP1/2, promote the ubiquitination and degradation of target proteins within the TNF receptor complex, modulating the signaling proteins. The high expression of the BIRC3 gene and its encoded protein, cIAP2, in RA regulates various cellular processes, including apoptosis, inflammatory signaling, immune response, MAPK signaling, and cell proliferation, thereby promoting FLS survival and inflammatory responses. Inhibiting BIRC3 expression can reduce the secretion of inflammatory cytokines by RA-FLS under both basal and inflammatory conditions and inhibit their proliferation. Although BIRC3 inhibitors show potential in RA treatment, their possible side effects must be carefully considered. Further research into the specific mechanisms of BIRC3, including its roles in cell signaling, apoptosis regulation, and immune evasion, is crucial for identifying new therapeutic targets and strategies.

Guanine nucleotide exchange factor RABGEF1 facilitates TNF-induced necroptosis by targeting cIAP1

Necroptosis is a form of regulated cell death that depends on the receptor-interacting serine-threonine kinase 3 (RIPK3) and mixed lineage kinase domain-like (MLKL). The molecular mechanisms underlying distinct instances of necroptosis have only recently begun to emerge. In the present study, we characterized RABGEF1 as a positive regulator of RIPK1/RIPK3 activation in vitro. Based on the overexpression and knockdown experiments, we determined that RABGEF1 accelerated the phosphorylation of RIPK1 and promoted necrosome formation in L929 cells. The pro-necrotic effect of RABGEF1 is associated with its E3 ubiquitin ligase activity and guanine nucleotide exchange factor (GEF) activity. We further confirmed that RABGEF1 interacts with cIAP1 protein by inhibiting its function and plays a regulatory role in necroptosis, which can be abolished by treatment with the antagonist Smac mimetic (SM)-164. In conclusion, our study highlights a potential and novel role of RABGEF1 in promoting TNF-induced cell necrosis.

Neosetophomone B induces apoptosis in multiple myeloma cells via targeting of AKT/SKP2 signaling pathway

Multiple myeloma (MM) is a hematologic malignancy associated with malignant plasma cell proliferation in the bone marrow. Despite the available treatments, drug resistance and adverse side effects pose significant challenges, underscoring the need for alternative therapeutic strategies. Natural products, like the fungal metabolite neosetophomone B (NSP-B), have emerged as potential therapeutic agents due to their bioactive properties. Our study investigated NSP-B's antitumor effects on MM cell lines (U266 and RPMI8226) and the involved molecular mechanisms. NSP-B demonstrated significant growth inhibition and apoptotic induction, triggered by reduced AKT activation and downregulation of the inhibitors of apoptotic proteins and S-phase kinase protein. This was accompanied by an upregulation of p21Kip1 and p27Cip1 and an elevated Bax/BCL2 ratio, culminating in caspase-dependent apoptosis. Interestingly, NSP-B also enhanced the cytotoxicity of bortezomib (BTZ), an existing MM treatment. Overall, our findings demonstrated that NSP-B induces caspase-dependent apoptosis, increases cell damage, and suppresses MM cell proliferation while improving the cytotoxic impact of BTZ. These findings suggest that NSP-B can be used alone or in combination with other medicines to treat MM, highlighting its importance as a promising phytoconstituent in cancer therapy.

In vitro evaluation of Neosetophomone B inducing apoptosis in cutaneous T cell lymphoma by targeting the FOXM1 signaling pathway

BACKGROUND

Cutaneous T cell lymphoma (CTCL) is a T cell-derived non-Hodgkin lymphoma primarily affecting the skin, with treatment posing a significant challenge and low survival rates.

OBJECTIVE

In this study, we investigated the anti-cancer potential of Neosetophomone B (NSP-B), a fungal-derived secondary metabolite, on CTCL cell lines H9 and HH.

METHODS

Cell viability was measured using Cell counting Kit-8 (CCK8) assays. Apoptosis was measured by annexin V/PI dual staining. Immunoblotting was performed to examine the expression of proteins. Applied Biosystems' high-resolution Human Transcriptome Array 2.0 was used to examine gene expression.

RESULTS

NSP-B induced apoptosis in CTCL cells by activating mitochondrial signaling pathways and caspases. We observed downregulated expression of BUB1B, Aurora Kinases A and B, cyclin-dependent kinases (CDKs) 4 and 6, and polo-like kinase 1 (PLK1) in NSP-B treated cells, which was further corroborated by Western blot analysis. Notably, higher expression levels of these genes showed reduced overall and progression-free survival in the CTCL patient cohort. FOXM1 and BUB1B expression exhibited a dose-dependent reduction in NSP-B-treated CTCL cells.FOXM1 silencing decreased cell viability and increased apoptosis via BUB1B downregulation. Moreover, NSP-B suppressed FOXM1-regulated genes, such as Aurora Kinases A and B, CDKs 4 and 6, and PLK1. The combined treatment of Bortezomib and NSP-B showed greater efficacy in reducing CTCL cell viability and promoting apoptosis compared to either treatment alone.

CONCLUSION

Our findings suggest that targeting the FOXM1 pathway may provide a promising therapeutic strategy for CTCL management, with NSP-B offering significant potential as a novel treatment option.

Differential regulation of BIRC2 and BIRC3 expression by inflammatory cytokines and glucocorticoids in pulmonary epithelial cells

Roles for the baculoviral inhibitor of apoptosis repeat-containing (BIRC) genes, BIRC2 and BIRC3, may include signaling to the inflammatory transcription factor, nuclear factor-κB (NF-κB) and protection from cell death. However, distinct functions for each BIRC are not well-delineated. Given roles for the epithelium in barrier function and host defence, BIRC2 and BIRC3 expression was characterized in pulmonary epithelial cell lines and primary human bronchial epithelial cells (pHBECs) grown as undifferentiated cells in submersion culture (SC) or as highly differentiated cells at air-liquid interface (ALI). In A549 cells, interleukin-1β (IL1B) and tumor necrosis factor α (TNF) induced BIRC3 mRNA (~20-50-fold), with maximal protein expression from 6-24 h. Similar effects occurred in BEAS-2B and Calu-3 cells, as well as SC and ALI pHBECs. BIRC2 protein was readily detected in unstimulated cells, but was not markedly modulated by IL1B or TNF. Glucocorticoids (dexamethasone, budesonide) modestly increased BIRC3 mRNA and protein, but showed little effect on BIRC2 expression. In A549 cells, BIRC3 mRNA induced by IL1B was unchanged by glucocorticoids and showed supra-additivity with TNF-plus-glucocorticoid. Supra-additivity was also evident for IL1B-plus-budesonide induced-BIRC3 in SC and ALI pHBECs. Using A549 cells, IL1B- and TNF-induced BIRC3 expression, and to a lesser extent, BIRC2, was prevented by NF-κB inhibition. Glucocorticoid-induced BIRC3 expression was prevented by silencing and antagonism of the glucocorticoid receptor. Whereas TNF, but not IL1B, induced degradation of basal BIRC2 and BIRC3 protein, IL1B- and TNF-induced BIRC3 protein remained stable. Differential regulation by cytokines and glucocorticoids shows BIRC2 protein expression to be consistent with roles in rapid signaling events, whereas cytokine-induced BIRC3 may be more important in later effects. While TNF-induced degradation of both BIRCs may restrict their activity, cytokine-enhanced BIRC3 expression could prime for its function. Finally, shielding from glucocorticoid repression, or further enhancement by glucocorticoid, may indicate a key protective role for BIRC3.

QiShenYiQi pill for myocardial collagen metabolism and apoptosis in rats of autoimmune cardiomyopathy

CONTEXT

QiShenYiQi pill (QSYQ) is a traditional Chinese medicine with a myocardial protective effect.

OBJECTIVE

To explore the effect of QSYQ on myocardial collagen metabolism in rats with autoimmune cardiomyopathy and explore the underlying mechanism from the aspect of apoptosis.

MATERIALS AND METHODS

We established an autoimmune cardiomyopathy model using Lewis rats. The rats were then randomly divided into six groups (n = 8): control, model, 3-methyladenine (15 mg/kg, intraperitoneal injection), QSYQ low-dose (135 mg/kg, gavage), QSYQ medium dose (270 mg/kg, gavage), and QSYQ high-dose (540 mg/kg, gavage) for four weeks. Van Gieson staining was applied for myocardial pathological characteristics, TUNEL fluorescence for myocardial cell apoptosis, enzyme-linked immunosorbent assay (ELISA) for serum PICP, PIIINP, and CTX-I levels, and western blot analysis for type I/III myocardial collagen, Bcl-2, Bax, and caspase-3 proteins.

RESULTS

Results showed that QSYQ (135, 270, or 540 mg/kg) significantly reduced the expression of myocardial type I/III collagen, and concentrations of serum PICP, PIIINP, and CTX-I in rats. Moreover, QSYQ could alleviate myocardial fibrosis more effectively at a higher dose. QSYQ could also inhibit myocardial apoptosis via downregulating Bcl-2 expression, and upregulating Bax and caspase-3 expression levels.

DISCUSSION AND CONCLUSIONS

The QSYQ can improve myocardial collagen metabolism by inhibiting apoptosis, which provides a potential therapeutic approach for autoimmune cardiomyopathy.

Advances in RIPK1 kinase inhibitors

Programmed necrosis is a new modulated cell death mode with necrotizing morphological characteristics. Receptor interacting protein 1 (RIPK1) is a critical mediator of the programmed necrosis pathway that is involved in stroke, myocardial infarction, fatal systemic inflammatory response syndrome, Alzheimer's disease, and malignancy. At present, the reported inhibitors are divided into four categories. The first category is the type I ATP-competitive kinase inhibitors that targets the area occupied by the ATP adenylate ring; The second category is type Ⅱ ATP competitive kinase inhibitors targeting the DLG-out conformation of RIPK1; The third category is type Ⅲ kinase inhibitors that compete for binding to allosteric sites near ATP pockets; The last category is others. This paper reviews the structure, biological function, and recent research progress of receptor interaction protein-1 kinase inhibitors.

Ferroptosis interaction with inflammatory microenvironments: Mechanism, biology, and treatment

Ferroptosis is a newly discovered form of regulated cell death. Ferroptosis is an iron-dependent lipid peroxidation reaction of cell membrane lipids, and it is closely related to the occurrence and development of many inflammatory diseases, such as ischemia-reperfusion injury, nonalcoholic steatohepatitis, and tumors. Although the precise role of ferroptosis in these inflammatory diseases is still unclear, recent evidence indicates that the association between ferroptosis and inflammatory diseases is related to the interaction of ferroptosis and inflammatory microenvironments. In inflammatory microenvironments, ferroptosis can be regulated by metabolic changes or the secretion of related substances between microorganisms and host cells or between host cells. At the same time, ferroptotic cells can also recruit immune cells by releasing injury-related molecular patterns, which in turn induces the generation of inflammatory microenvironments. Molecular crosstalk between ferroptosis and other cell death types also exists in inflammatory microenvironments. In addition, the interaction of ferroptosis and the tumor microenvironment is also correlated with tumor growth. This article reviews the main metabolic processes of ferroptosis, describes the interaction mechanism between ferroptosis and inflammatory microenvironments, and summarizes the role of ferroptosis in the treatment of diseases.

Classical epithelial-mesenchymal transition (EMT) and alternative cell death process-driven blebbishield metastatic-witch (BMW) pathways to cancer metastasis

Metastasis is a pivotal event that accelerates the prognosis of cancer patients towards mortality. Therapies that aim to induce cell death in metastatic cells require a more detailed understanding of the metastasis for better mitigation. Towards this goal, we discuss the details of two distinct but overlapping pathways of metastasis: a classical reversible epithelial-to-mesenchymal transition (hybrid-EMT)-driven transport pathway and an alternative cell death process-driven blebbishield metastatic-witch (BMW) transport pathway involving reversible cell death process. The knowledge about the EMT and BMW pathways is important for the therapy of metastatic cancers as these pathways confer drug resistance coupled to immune evasion/suppression. We initially discuss the EMT pathway and compare it with the BMW pathway in the contexts of coordinated oncogenic, metabolic, immunologic, and cell biological events that drive metastasis. In particular, we discuss how the cell death environment involving apoptosis, ferroptosis, necroptosis, and NETosis in BMW or EMT pathways recruits immune cells, fuses with it, migrates, permeabilizes vasculature, and settles at distant sites to establish metastasis. Finally, we discuss the therapeutic targets that are common to both EMT and BMW pathways.

Anticancer activity of Neosetophomone B by targeting AKT/SKP2/MTH1 axis in leukemic cells

Neosetophomone B (NSP-B), a meroterpenoid fungal secondary metabolite, was investigated for its anticancer potential in leukemic cell lines (K562 and U937). NSP-B treatment of leukemic cells suppressed cell viability by triggering apoptotic cell death. Apoptosis induced by NSP-B is triggered by mitochondrial signaling and caspase activation. Additionally, NSP-B treatment of leukemic cells causes AKT's inactivation accompanied by downregulation of SKP2 oncogene and MTH1 with a concomitant increase of p21Cip1and p27Kip1. Furthermore, NSP-B causes suppression of antiapoptotic proteins, including cIAP1, cIAP2, XIAP, survivin and BCl-XL. Overall, NSP-B reduces cell viability by mitochondrial and caspase-dependent apoptosis. The inhibition of AKT and SKP2 axis could be a promising therapeutic target for leukemia treatment.

Perkinsus marinus suppresses in vitro eastern oyster apoptosis via IAP-dependent and caspase-independent pathways involving TNFR, NF-kB, and oxidative pathway crosstalk

The protozoan parasite Perkinsus marinus causes Dermo disease in eastern oysters, Crassostrea virginica, and can suppress apoptosis of infected hemocytes using incompletely understood mechanisms. This study challenged hemocytes in vitro with P. marinus for 1 h in the presence or absence of caspase inhibitor Z-VAD-FMK or Inhibitor of Apoptosis protein (IAP) inhibitor GDC-0152. Hemocytes exposure to P. marinus significantly reduced granulocyte apoptosis, and pre-incubation with Z-VAD-FMK did not affect P. marinus-induced apoptosis suppression. Hemocyte pre-incubation with GDC-0152 prior to P. marinus challenge further reduced apoptosis of granulocytes with engulfed parasite, but not mitochondrial permeabilization. This suggests P. marinus-induced apoptosis suppression may be caspase-independent, affect an IAP-involved pathway, and occur downstream of mitochondrial permeabilization. P. marinus challenge stimulated hemocyte differential expression of oxidation-reduction, TNFR, and NF-kB pathways. WGCNA analysis of P. marinus expression in response to hemocyte exposure revealed correlated protease, kinase, and hydrolase expression that could contribute to P. marinus-induced apoptosis suppression.

Phytochemical identification, acute and subchronic oral toxicity assessments of hydroalcoholic extract of Acroptilon repens in BALB/c mice: A toxicological and mechanistic study

Acroptilon repens (L.) DC, commonly known as Rhaponticum repens, is a popular traditional phytomedicine. The current study was conducted to evaluate the acute and subchronic toxicity of the hydroalcoholic extract of this herb with regard to its terpenoid contents in a BALB/c mice model and to investigate the toxicity of this medicinal herb. Identification of extract components of the plant was done using gas chromatography (GC)-mass spectrometry. In order to establish the acute toxicity model, a single dose of 2000 mg/kg of the extract was given orally to male mice and in the subchronic toxicity study, the extract was consecutively administered at doses 250, 500, and 1000 mg/kg for 28 days. After 28 and 42 days, signs of toxicity and mortality were observed. Organ weight changes and the toxicity-associated parameters such as biochemical indicators, oxidative stress indices, mitochondrial parameters, apoptosis-associated gene expression levels, and pro-inflammatory cytokines were evaluated along with the histopathological examination. GC analysis showed that the terpenoids are the major components of the extract. The LD50 value (2 g/kg) was obtained in the acute toxicity assay; the subchronic administration caused a significant elevation in the serum biomarkers as well as in the levels of lipid peroxidation, protein carbonyl, and ROS. Besides, significant reductions in the superoxide dismutase and catalase activities were observed. This toxic effect was further confirmed by histological studies, cytokine assay, and gene expression assays. Following the treatment discontinuation, the abnormalities in the values of biochemical parameters and histopathological changes returned to normal. These findings demonstrate that the subchronic administration of the hydroalcoholic extract of A. repens can reversibly cause toxicity by inducing oxidative stress and mitochondrial dysfunction.

Chronic Ethanol Consumption Induces Osteopenia via Activation of Osteoblast Necroptosis

Chronic high-dose alcohol consumption impairs bone remodeling, reduces bone mass, and increases the risk of osteoporosis and bone fracture. However, the mechanisms underlying alcohol-induced osteoporosis are yet to be elucidated. In this study, we showed that excess intake of ethyl alcohol (EtOH) resulted in osteopenia and osteoblast necroptosis in mice that led to necrotic lesions and reduced osteogenic differentiation in bone marrow mesenchymal stem cells (BMMSCs). We found that EtOH treatment led to the activation of the RIPK1/RIPK3/MLKL signaling, resulting in increased osteoblast necroptosis and decreased osteogenic differentiation and bone formation both in vivo and in vitro. We further discovered that excessive EtOH treatment-induced osteoblast necroptosis might partly depend on reactive oxygen species (ROS) generation; concomitantly, ROS contributed to necroptosis of osteoblasts through a positive feedback loop involving RIPK1/RIPK3. In addition, blocking of the RIPK1/RIPK3/MLKL signaling by necrostatin-1 (Nec-1), a key inhibitor of RIPK1 kinase in the necroptosis pathway, or antioxidant N-acetylcysteine (NAC), an inhibitor of ROS, could decrease the activation of osteoblast necroptosis and ameliorate alcohol-induced osteopenia both in vivo and in vitro. Collectively, we demonstrated that chronic high-dose alcohol consumption induced osteopenia via osteoblast necroptosis and revealed that RIPK1 kinase may be a therapeutic target for alcohol-induced osteopenia.

Epigenetic Markers Are Associated With Differences in Isocyanate Biomarker Levels in Exposed Spray-Painters

Isocyanates are respiratory and skin sensitizers that are one of the main causes of occupational asthma globally. Genetic and epigenetic markers are associated with isocyanate-induced asthma and, before asthma develops, we have shown that genetic polymorphisms are associated with variation in plasma and urine biomarker levels in exposed workers. Inter-individual epigenetic variance may also have a significant role in the observed biomarker variability following isocyanate exposure. Therefore, we determined the percent methylation for CpG islands from DNA extracted from mononuclear blood cells of 24 male spray-painters exposed to 1,6-hexamethylene diisocyanate (HDI) monomer and HDI isocyanurate. Spray-painters' personal inhalation and skin exposure to these compounds and the respective biomarker levels of 1,6-diaminohexane (HDA) and trisaminohexyl isocyanurate (TAHI) in their plasma and urine were measured during three repeated industrial hygiene monitoring visits. We controlled for inhalation exposure, skin exposure, age, smoking status, and ethnicity as covariates and performed an epigenome-wide association study (EWAS) using likelihood-ratio statistical modeling. We identified 38 CpG markers associated with differences in isocyanate biomarker levels (Bonferroni < 0.05). Annotations for these markers included 18 genes: ALG1, ANKRD11, C16orf89, CHD7, COL27A, FUZ, FZD9, HMGN1, KRT6A, LEPR, MAPK10, MED25, NOSIP, PKD1, SNX19, UNC13A, UROS, and ZFHX3. We explored the functions of the genes that have been published in the literature and used GeneMANIA to investigate gene ontologies and predicted protein-interaction networks. The protein functions of the predicted networks include keratinocyte migration, cell-cell adhesions, calcium transport, neurotransmitter release, nitric oxide production, and apoptosis regulation. Many of the protein pathway functions overlap with previous findings on genetic markers associated with variability both in isocyanate biomarker levels and asthma susceptibility, which suggests there are overlapping protein pathways that contribute to both isocyanate toxicokinetics and toxicodynamics. These predicted protein networks can inform future research on the mechanism of allergic airway sensitization by isocyanates and aid in the development of mitigation strategies to better protect worker health.

EGF-Induced miR-223 Modulates Goat Mammary Epithelial Cell Apoptosis and Inflammation via ISG15

The health of mammary gland is essential for lactation. Epidermal growth factor (EGF) is reported to play an important role in lactation initiation and miR-223 is a conserved microRNA in anti-inflammation. In this study, EGF was found to induce a higher expression of miR-223 in goat mammary epithelial cell (gMEC). The downstream genes of miR-223 were screened by RNA sequencing, including Interferon-stimulated gene product 15 (ISG15), a pivotal immune responder, which was detected to be downregulated by EGF and miR-223. Due to the correlation between inflammation and apoptosis, the gMEC apoptosis modulated by EGF, miR-223, and ISG15 was investigated, and the protein expressions of Bcl-2/Bax, Caspase 3 and p53 were examined to evaluate the apoptosis of gMEC. The protein expressions of p-STAT3/STAT3, PR, FOXC1, and HOXA10, which had been shown to be related to inflammation, were detected to assess the inflammation of gMEC. This study provided a regulation axis, EGF/miR-223/ISG15, and illustrated its regulation to gMEC apoptosis and inflammation.

Controlled decompression alleviates early brain injury in rabbit intracranial hypertension model by regulating apoptosis/necroptosis

Purpose

To evaluate the effects of controlled decompression and rapid decompression, explore the potential mechanism, provide the theoretical basis for the clinical application, and explore the new cell death method in intracranial hypertension.

Methods

Acute intracranial hypertension was triggered in rabbits by epidural balloon compression. New Zealand white rabbits were randomly put into the sham group, the controlled decompression group, and the rapid decompression group. Brain water content, etc., was used to evaluate early brain injury. Western blotting and double immunofluorescence staining were used to detect necroptosis and apoptosis.

Results

Brain edema, neurological dysfunction, and brain injury appeared after traumatic brain injury (TBI). Compared with rapid decompression, brain water content was significantly decreased, neurological scores were improved by controlled decompression treatment. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining and Nissl staining showed neuron death decreased in the controlled decompression group. Compared with rapid decompression, it was also found that apoptosis-related protein caspase-3/ tumor necrosis factor (TNF)-a was reduced markedly in the brain cortex and serum, and the expression levels of necroptosis-related protein, receptor-interacting protein 1 (RIP1)/receptor-interacting protein 1 (RIP3) reduced significantly in the controlled decompression group.

Conclusions

Controlled decompression can effectively reduce neuronal damage and cerebral edema after craniocerebral injury and, thus, protect the brain tissue by alleviating necroptosis and apoptosis.

Combined Anti-Cancer Effects of Platycodin D and Sorafenib on Androgen-Independent and PTEN-Deficient Prostate Cancer

Castration-resistant (androgen-independent) and PTEN-deficient prostate cancer is a challenge in clinical practice. Sorafenib has been recommended for the treatment of this type of cancer, but is associated with several adverse effects. Platycodin D (PD) is a triterpene saponin with demonstrated anti-cancer effects and a good safety profile. Previous studies have indicated that PC3 cells (PTEN -/-, AR -/-) are sensitive to PD, suggesting that it may also be a useful treatment for castration-resistance prostate cancer. We herein investigated the effects of combining PD with sorafenib to treat PTEN-deficient prostate cancer cells. Our data show that PD promotes sorafenib-induced apoptosis and cell cycle arrest in PC3 cells. Of interest, PD only promoted the anti-cancer effects of sorafenib in Akt-positive and PTEN-negative prostate cancer cells. Mechanistic studies revealed that PD promoted p-Akt ubiquitination by increasing the p-Akt level. PD also increased the protein and mRNA expression of FOXO3a, the downstream target of Akt. Meanwhile, PD promoted the activity of FOXO3a and increased the protein expression of Fasl, Bim and TRAIL. Interestingly, when FOXO3a expression was inhibited, the antitumor effects of both PD and sorafenib were individually inhibited, and the more potent effects of the combination treatment were inhibited. Thus, the combination of PD and sorafenib may exert potent anti-cancer effects specifically via FOXO3a. The use of Akt inhibitors or FOXO3a agonists, such as PD, may represent a promising approach for the treatment of androgen-independent and PTEN-deficient prostate cancer.

Proteomic Level Changes on Treatment in MCF-7/DDP Breast Cancer Drug- Resistant Cells

Background

LCL161, a SMAC’S small molecule mimetic, can bind to a variety of IAPs and activate Caspases. We found that on its own, LCL161induces apoptosis of drug-resistant breast cancer cells by binding to a variety of IAPs and activating Caspases. However, when LCL161 is used in combination with Caspase Inhibitors (CI), its capacity to induce apoptosis of breast cancer cells is enhanced.

Objective

To carry out proteomic and bioinformatics analysis of LCL161 in combination with CI. We aim to identify the key proteins and mechanisms of breast cancer drug-resistant apoptosis, thereby aiding in the breast cancer drug resistance treatment and identification of drug targeting markers.

Methods

Cell culture experiments were carried out to explore the effect of LCL161 combined with CI on the proliferation of breast cancer drug-resistant cells. Proteomic analysis was carried out to determine the protein expression differences between breast cancer drug-resistant cells and LCL161 combined with CI treated cells. Bioinformatics analysis was carried out to determine its mechanism of action. Validation of proteomics results was done using Parallel Reaction Monitoring (PRM).

Results

Cell culture experiments showed that LCL161 in combination with CI can significantly promote the apoptosis of breast cancer drug-resistant cells. Up-regulation of 92 proteins and down-regulation of 114 proteins protein were noted, of which 4 were selected for further validation.

Conclusion

Our results show that LCL161 combined with CI can promote the apoptosis of drug-resistant breast cancer cells by down-regulation of RRM2, CDK4, and ITGB1 expression through Cancer pathways, p53 or PI3K-AKT signaling pathway. In addition, the expression of CDK4, RRM2, and CDC20 can be down-regulated by the nuclear receptor pathway to affect DNA transcription and replication, thereby promoting apoptosis of breast cancer drug-resistant cells.

TRIM21, a New Component of the TRAIL-Induced Endogenous Necrosome Complex

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a well-known apoptosis inducer and a potential anticancer agent. When caspases and inhibitors of apoptosis proteins (IAPs) are inhibited, TRAIL induces necroptosis. Molecular mechanisms of necroptosis rely on kinase activation, and on the formation of a necrosome complex, bringing together the receptor-interacting protein kinases 1 and 3 (RIPK1, RIPK3), and the mixed lineage kinase domain-like protein (MLKL). In this study, mass spectrometry approach allowed to identify the tripartite motif containing 21 (TRIM21), an E3 ubiquitin-protein ligase as a new partner of the endogenous TRAIL-induced necrosome. Alteration of TRIM21 expression level, obtained by transient transfection of HT29 or HaCat cells with TRIM21-targeted siRNAs or cDNA plasmids coding for TRIM21 demonstrated that TRIM21 is a positive regulator of TRAIL-induced necroptosis. Furthermore, the invalidation of TRIM21 expression in HT29 cells by CRISPR-Cas9 technology also decreased cell sensitivity to TRAIL-induced necroptosis, a shortcoming associated with a reduction in MLKL phosphorylation, the necroptosis executioner. Thus, TRIM21 emerged as a new partner of the TRAIL-induced necrosome that positively regulates the necroptosis process.

cIAP2 expression and clinical significance in pigmented villonodular synovitis

Pigmented villonodular synovitis (PVNS) is a rare hyperplasia disease of the synovium with a predilection for the knee in either a localized (LPVNS) or a diffuse form (DPVNS). But the exact cause is not clear. The aim of this study was to explore the relationship between the expression of cellular inhibitor of apoptosis 2 (cIAP2) and proliferation, apoptosis, invasive growth and postoperative recurrence in PVNS. Clinical significance of cIAP2 expression in synovium from 63 patients' knee joints with PVNS (40 DPVNS; 23 LPVNS) were investigated with 20 normal subjects acting as controls. The cIAP2 gene was screened by Human Cancer Pathway Finder PCR Array and real-time polymerase chain reaction (RT-PCR). We also used immunohistochemistry to detect cIAP2 and proliferating cell nuclear antigen (PCNA) protein expression and analyzed their relationship with PVNS type, invasive growth, and postoperative recurrence. The expression of cIAP2, PCNA, caspase-8, caspase-9 and caspase-3 protein was tested in Western blot. Screening results of Human Cancer Pathway Finder PCR array and RT-PCR showed significantly more cIAP2 mRNA in DPVNS synovium than in normal or LPVNS synovium (P < 0.05). Immunohistochemistry and western blot showed that the cIAP2 protein expression level in DPVNS was significantly higher than in LPVNS tissue (P < 0.01). As cIAP2 expression increased, the expression of PCNA increased (P < 0.05) and expression of cleaved caspase-3, -8, -9 decreased (P < 0.01). cIAP2 and PCNA overexpression were found to be related to ligament and bone erosion in PVNS and to disease recurrence (P < 0.05). This study suggested that cIAP2 overexpression plays an important role in the anti-apoptotic, proliferative and invasive growth of PVNS, which may account for the recurrence and poor prognosis of DPVNS.

Galleria mellonella larvae fat body disruption (Lepidoptera: Pyralidae) caused by the venom of Habrobracon brevicornis (Hymenoptera: Braconidae)

The ability of Habrobracon brevicornis venom to elevate the nutritional suitability of a host by affecting the host larvae fat body condition was studied. To understand whether H. brevicornis crude venom impacts the host biochemical profile, the concentrations of total lipids and main sugars in the host larvae lymph were analyzed. All measurements were carried out during the first 3 days after envenomation. A significant increase in the lipid level was fixed only on the second day after envenomation. A significant increase in the total trehalose count was detected during all 3 days, while a significant increase in glucose concentration was noted only on the first day. Well-observed disruptions were fixed in thin and semithin sections of the G. mellonella larval fat body starting from the second day after envenomation. Significant increases in both phospholipase A₂ and C enzyme activity as well as acid proteases were detected in the wax moth fat body after envenomation during all experimental times. At the same time, imbalances in the antioxidant system, including changes in the activities of superoxide dismutase, peroxidases, catalase, and glutathione-S-transferase, were detected. The reliable increase in the expression of the gene encoding Hsp70 was fixed both for 24 and 48 h after envenomation, while a reliable increase in the expression of the gene encoding inhibitor of apoptosis protein was detected only 24 h after wax moth larvae envenomation. Considering the absence of DNA fragmentation, the imbalance in the "ROS/antioxidants" system, and the increased activity of phospholipases and acid proteases in the fat body cells from envenomated wax moth larvae, we can hypothesize that the fat body disruption occurs in a necrotic manner. The results of the work expand the knowledge about the biochemical aspects of interaction between ectoparasitoids and their hosts.

NLRP12 negatively regulates EtOH-induced liver macrophage activation via NF-κB pathway and mediates hepatocyte apoptosis in alcoholic liver injury

Alcohol-induced liver injury is characterized by abnormal liver dysfunction and excessive inflammation response. Recent years a wealth of data have been yielded indicating that EtOH (ethyl alcohol)-induced macrophage activation along with liver inflammation plays a dominating role in the progression of alcohol-induced liver injury. Here we found high expression of NLRP12 (Nucleotide-binding oligomerization domain protein 12, which is generally considered to be a negative regulator of inflammatory response) in EtOH-fed mouse liver tissue, primary Kupffer cells and EtOH-induced RAW264.7 cells. Additionally, overexpression of NLRP12 following Ad (adenovirus)-NLRP12-EGFP contributed to the attenuation of steatosis and inflammation in EtOH-fed mice model and EtOH-primed RAW264.7 cells. In parallel, Knockdown of NLRP12 aggravated the inflammatory response in RAW264.7 cells triggered by EtOH. Meanwhile, after administration of overexpression or inhibition of NLRP12 expression in vitro, the expression of phosphorylated protein of NF-kB signaling pathway was significantly affected. After increasing or decreasing the expression of NLRP12 in RAW264.7 cells, AML-12 cells were cultured with the supernatant of RAW264.7 cells stimulated by EtOH, and the percent of apoptosis ratio of AML-12 cells was remarkably altered. The study suggested that reduced inflammatory response induced by NLRP12-mediated inhibition of NF-kB pathway participated in the decrease of hepatocyte apoptosis in alcohol-induced liver injury. Collectively, these findings suggested the significance of NLRP12-mediated macrophage activation in alcohol-induced liver injury.

Apoptosis of lung cells regulated by mitochondrial signal pathway in crotonaldehyde-induced lung injury

Crotonaldehyde, a highly toxic α, β-unsaturated aldehyde, is a ubiquitous hazardous pollutant. Because of its extreme toxicity and ubiquity in all types of smoke, most current research focuses on the lung toxicity of such air pollutants. However, the specific mechanism of pulmonary toxicity caused by crotonaldehyde remains unclear, especially after long-term exposure to crotonaldehyde at low dose. Therefore, the aim of the present study is to determine whether crotonaldehyde-induced oxidative damage and inflammation promote apoptosis in rats via the mitochondrial pathway using histopathology, immunohistochemistry, biochemistry analysis and Western blot analysis. The results show that crotonaldehyde elicited oxidative damage and inflammation in rats in a concentration-dependent manner. Crotonaldehyde-induced lung injury which was confirmed by H&E, Masson's trichrome staining and TUNEL. And crotonaldehyde-induced lung cell apoptosis showed a concentration-response relationship. Immunohistochemistry and Western blot results showed that apoptotic mitochondrial signaling pathway is abnormally activated in crotonaldehyde-induced lung injury. Collectively, this study demonstrates that exposure of rats to crotonaldehyde induces lung injury by inducing apoptosis, which is related to oxidative damage and inflammation through mitochondrial pathway.

Calcitriol inhibits apoptosis via activation of autophagy in hyperosmotic stress stimulated corneal epithelial cells in vivo and in vitro

BACKGROUND

Previously, calcitriol has been demonstrated as a potential therapeutic agent for dry eye, whilst its role on corneal epithelium death remains unclear. This study aims to investigate the relationship between apoptosis and autophagy on dry eye related scenario, as well as the effect of calcitriol and its potential mechanism.

METHODS

In vitro, immortalized human corneal epithelial cells (iHCEC) were cultured in hyperosmotic medium with or without various concentrations of calcitriol and other reagents. In vivo, Wistar rats were applied with benzalkonium chloride to induce dry eye. Then rats were topically treated with calcitriol (10^-6 M) for 14 days. Autophagy flux (LC3B-II and SQSTM1/P62) was examined by western blotting or immunostaining. To test cell apoptosis, western blotting for cleaved caspase-3, Annexin V/PI double staining and TUNEL assay were used. CCK-8 assay was performed to detect the cell viability. Small interfering RNA was used to knock down the expression of vitamin D receptor in iHCECs.

RESULTS

Autophagy activation could protect iHCECs against HS induced apoptosis in vitro, and calcitriol was able to augment autophagy flux via VDR signaling, shown as the remarkably elevated expression of LC3B-II, as well as the declined p62 expression. In vivo results further supported the protective role of calcitriol on corneal epithelium apoptosis through promoting autophagy in dry eye rats.

CONCLUSION

The current study indicated that autophagy was an adaptive change of corneal epithelial cells in response to hyperosmotic stress and calcitriol could prevent cells from apoptosis via further activation of autophagy through VDR pathway.

Bufalin Induces Glioma Cell Death by Apoptosis or Necroptosis

Introduction

Bufalin is a component of Chinese traditional medicine, Chansu, which is reported to induce cell death among various kinds of tumors. Apoptosis evasion is a common problem of cancer treatment.

Materials and Methods

The proliferation of U-87 and U-373 treated by bufalin combined with or without apoptosis inhibitor was detected by MTT assay. The protein levels related to apoptosis and necroptosis were measured by Western blotting. Immunoprecipitation (IP) was applied for monitoring the formation of necrosome. The gene knockdown by CRISPR/Cas9 was applied to determine the roles of the proteins in apoptosis and necroptosis.

Results

In this study, we found that bufalin could induce apoptosis or necroptosis when U-87 and U-373 escaped from apoptosis. Bufalin triggered cell death by upregulating tumor necrosis factor (TNF) -α, TNF receptor 1 (TNFR1) and receptor-interacting protein 1 (RIPK1). Antagonizing cellular inhibitor of apoptosis 1 (cIAP1) and cIAP2 were also contributory. Caspase-8 activation led to apoptosis. When caspase-8 was functionally lost, necrosome consisted of RIPK1, receptor-interacting protein 3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL) formed and necroptosis happened. The knockdown of above genes or the drug treatment confirmed the mechanism of bufalin-induced cell death. Cytotoxicity of bufalin to caspase-8 knockdown cell lines made control cell lines more sensitive to bufalin in their mixture.

Discussion

The cytotoxicity of bufalin to U-87 and U-373 was by inducing apoptosis or necroptosis when they were sensitive to apoptosis or not. The results indicated that seeking for treatments that could induce apoptosis and necroptosis was a good solution for the tumor evasion of apoptosis.

Ferroptosis as an emerging target in inflammatory diseases

Cell survival or death is one critical issue in inflammatory responses. Ferroptosis, which is characterized by iron-dependent lethal lipid peroxidation, has been found to participate in the development of cancers, degenerative brain diseases and ischemia-reperfusion injuries. Incorporation of polyunsaturated fatty acids (PUFAs) into cellular membranes represents a vulnerability to invasion of microbials and sterile stimuli. In addition, the competition for iron in the battle between microbials and host cells underlies infection development. Although host cells have been equipped with complex antioxidant systems to combat lethal accumulation of lipid peroxidation, emerging evidence suggests several pathogens may target PUFAs in the cell membrane, and manipulate ferroptosis as a way for pathogen propagation. Moreover, ferroptosis takes part in the progression of sterile inflammations, such as cigarette smoke-induced chronic obstructive pulmonary disease, stroke and ischemia-reperfusion injuries. As iron-dependent oxidative stress and lipid peroxidation are common features for ferroptosis and inflammatory diseases, underlying mechanisms linking such pathological conditions will be discussed in this review. Progress in the research of ferroptosis may shed more light on the etiology and treatment of inflammatory diseases.

Phenotypic high-throughput screening platform identifies novel chemotypes for necroptosis inhibition

Regulated necrosis or necroptosis, mediated by receptor-interacting kinase 1 (RIPK1), RIPK3 and pseudokinase mixed lineage kinase domain-like protein (MLKL), contributes to the pathogenesis of inflammatory, infectious and degenerative diseases. Recently identified necroptosis inhibitors display moderate specificity, suboptimal pharmacokinetics, off-target effects and toxicity, preventing these molecules from reaching the clinic. Here, we developed a cell-based high-throughput screening (HTS) cascade for the identification of small-molecule inhibitors of necroptosis. From the initial library of over 250,000 compounds, the primary screening phase identified 356 compounds that strongly inhibited TNF-α-induced necroptosis, but not apoptosis, in human and murine cell systems, with EC50 < 6.7 μM. From these, 251 compounds were tested for RIPK1 and/or RIPK3 kinase inhibitory activity; some were active and several have novel mechanisms of action. Based on specific chemical descriptors, 110 compounds proceeded into the secondary screening cascade, which then identified seven compounds with maximum ability to reduce MLKL activation, IC50 >100 μM, EC50 2.5-11.5 μM under long-term necroptosis execution in murine fibroblast L929 cells, and full protection from ATP depletion and membrane leakage in human and murine cells. As a proof of concept, compound SN-6109, with binding mode to RIPK1 similar to that of necrostatin-1, confirmed RIPK1 inhibitory activity and appropriate pharmacokinetic properties. SN-6109 was further tested in mice, showing efficacy against TNF-α-induced systemic inflammatory response syndrome. In conclusion, a phenotypic-driven HTS cascade promptly identified robust necroptosis inhibitors with in vivo activity, currently undergoing further medicinal chemistry optimization. Notably, the novel hits highlight the opportunity to identify new molecular mechanisms of action in necroptosis.

An inhibitor of apoptosis protein (EsIAP1) from Chinese mitten crab Eriocheir sinensis regulates apoptosis through inhibiting the activity of EsCaspase-3/7-1

Inhibitor of apoptosis proteins (IAPs) maintain the balance between cell proliferation and cell death by inhibiting caspase activities and mediating immune responses. In the present study, a homolog of IAP (designated as EsIAP1) was identified from Chinese mitten crab Eriocheir sinensis. EsIAP1 consisted of 451 amino acids containing two baculoviral IAP repeat (BIR) domains with the conserved Cx2 Cx6 Wx3 Dx5 Hx6 C motifs. EsIAP1 mRNA was expressed in various tissues and its expression level in hemocytes increased significantly (p < 0.01) at 12–48 h after lipopolysaccharide stimulation. In the hemocytes, EsIAP1 protein was mainly distributed in the cytoplasm. The hydrolytic activity of recombinant EsCaspase-3/7-1 against the substrate Ac-DEVD-pNA decreased after incubation with rEsIAP1. Moreover, rEsIAP1 could directly combine with rEsCaspase-3/7-1 in vitro. After EsIAP1 was interfered by dsRNA, the mRNA expression and the hydrolytic activity of EsCaspase-3/7-1 increased significantly, which was 2.26-fold (p < 0.05) and 1.71-fold (p < 0.05) compared to that in the dsGFP group, respectively. These results collectively demonstrated that EsIAP1 might play an important role in apoptosis pathway by regulating the activity of EsCaspase-3/7-1 in E. sinensis.

Apoptosis and necroptosis in the liver: a matter of life and death

Cell death represents a basic biological paradigm that governs outcomes and long-term sequelae in almost every hepatic disease condition. Acute liver failure is characterized by massive loss of parenchymal cells but is usually followed by restitution ad integrum. By contrast, cell death in chronic liver diseases often occurs at a lesser extent but leads to long-term alterations in organ architecture and function, contributing to chronic hepatocyte turnover, the recruitment of immune cells and activation of hepatic stellate cells. These chronic cell death responses contribute to the development of liver fibrosis, cirrhosis and cancer. It has become evident that, besides apoptosis, necroptosis is a highly relevant form of programmed cell death in the liver. Differential activation of specific forms of programmed cell death might not only affect outcomes in liver diseases but also offer novel opportunities for therapeutic intervention. Here, we summarize the underlying molecular mechanisms and open questions about disease-specific activation and roles of programmed cell death forms, their contribution to response signatures and their detection. We focus on the role of apoptosis and necroptosis in acute liver injury, nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH) and liver cancer, and possible translations into clinical applications.

Fenretinide Inhibits Neutrophil Recruitment and IL-1β Production in Aspergillus fumigatus Keratitis

Purpose:

Fungal keratitis is a major cause of corneal ulcers, resulting in significant visual impairment and blindness. Fenretinide, a derivative of vitamin A, has been shown to suppress inflammation in a multitude of diseases. In this study, we aimed to characterize the effect of fenretinide in Aspergillus fumigatus keratitis of the eye in a mouse model.

Methods:

In vivo and in vitro experiments were performed in mouse models and THP-1 macrophage cell cultures infected with A. fumigatus, respectively. Experimental subjects were first pretreated with fenretinide, and then the effect of the compound was assessed with clinical evaluation, neutrophil staining, myeloperoxidase assay, quantitative polymerase chain reaction (qRT-PCR), and western blot.

Results:

We confirmed that fenretinide contributed to protection of corneal transparency during early mouse A. fumigatus keratitis by reducing neutrophil recruitment, decreasing myeloperoxidase (MPO) levels and increasing apoptosis. Compared with controls, fenretinide impaired proinflammatory cytokine interleukin 1 beta (IL-1β) production in response to A. fumigatus exposure with contributions by lectin-type oxidized LDL receptor 1 (LOX-1) and c-Jun N-terminal kinase (JNK).

Conclusions:

Together, these findings demonstrate that fenretinide may suppress inflammation through reduced neutrophil recruitment and inflammatory cytokine production in A. fumigatus keratitis.

IAP genes partake weighty roles in the astogeny and whole body regeneration in the colonial urochordate Botryllus schlosseri

Inhibitors of Apoptosis Protein (IAP) genes participate in processes like apoptosis, proliferation, innate immunity, inflammation, cell motility, differentiation and in malignancies. Here we reveal 25 IAP genes in the tunicate Botryllus schlosseri's genome and their functions in two developmental biology phenomena, a new mode of whole body regeneration (WBR) induced by budectomy, and blastogenesis, the four-staged cycles of botryllid ascidian astogeny. IAP genes that were specifically upregulated during these developmental phenomena were identified, and protein expression patterns of one of these genes, IAP28, were followed. Most of the IAP genes upregulation recorded at blastogenetic stages C/D was in concert with the upregulation at 100 μM H₂O₂ apoptotic-induced treatment and in parallel to expressions of AIF1, Bax, Mcl1, caspase 2 and two orthologues of caspase 7. Wnt agonist altered the takeover duration along with reduced IAP expressions, and displacement of IAP28⁺ phagocytes. WBR was initiated solely at blastogenetic stage D, where zooidal absorption was attenuated and regeneration centers were formed either from remains of partially absorbed zooids or from deformed ampullae. Subsequently, bud-bearing zooids developed, in concert with a massive IAP28-dependent phagocytic wave that eliminated the old zooids, then proceeded with the establishment of morphologically normal-looking colonies. IAP4, IAP14 and IAP28 were also involved in WBR, in conjunction with the expression of the pro-survival PI3K-Akt pathway. IAPs function deregulation by Smac mimetics resulted in severe morphological damages, attenuation in bud growth and differentiation, and in destabilization of colonial coordination. Longtime knockdown of IAP functions prior to the budectomy, resulted in colonial death.

Greensporone C, a Freshwater Fungal Secondary Metabolite Induces Mitochondrial-Mediated Apoptotic Cell Death in Leukemic Cell Lines

Therapeutic agents used in the treatment of cancer are known to develop resistance against cancer cells. Hence, there is a continuing need to investigate novel agents for the treatment and management of cancer. Antitumor activity of greensporone C (GC), a new resorcylic acid lactone isolated from an organic extract of a culture of a Halenospora sp. freshwater fungus, was subjected for screening against a panel of leukemic cell lines (K562, U937, and AR320). In all the three cell lines, cell proliferation was inhibited in dose-dependent fashion. GC further arrested the cells in SubG0 phase in dose-dependent manner. Annexin V/PI dual staining data confirmed apoptotic death of treated K562 and U937 leukemic cells. Treatment with GC suppressed constitutively phosphorylated AKT and downregulated expression of inhibitor of apoptotic proteins XIAP, cIAP-1, and cIAP-2. In summation to this, GC-treated leukemic cells upregulated protein expression of pro-apoptotic proteins, Bax with concomitant decrease in expression of anti-apoptotic proteins including Bcl-2 and Bcl-xL. Upregulation of Bax was associated with cytochrome c release which was confirmed from the collapse of mitochondrial membrane. Released cytochrome c further activated caspase cascade which in turn initiated apoptosis process. Anticancer activity of this isolated fungal compound GC was potentiated via stimulating production of reactive oxygen species (ROS) along with depletion of reduced glutathione (GSH) levels in K562 and U937 leukemic cells. Pretreatment of these cells with N-acetyl cysteine prevented GC-induced depletion of reduced GSH level and mitochondrial-caspase-induced apoptosis. Altogether, our data show that GC modulates the apoptotic response of human leukemic cells and raises the possibility of its use as a novel therapeutic strategy for hematological malignancies.

G-quartet oligonucleotide mediated delivery of functional X-linked inhibitor of apoptosis protein into retinal cells following intravitreal injection

There is currently no efficient method available for the delivery of full length functional proteins into the cytoplasm of retinal cells in vivo. Historically, the most successful approach for the treatment of retinal diseases has been intravitreal injection of antibodies or recombinant proteins, but this approach is not yet utilized for the delivery of proteins that require intracellular access for a therapeutic effect. Here we describe a platform for the delivery of functional proteins into ganglion cells, photoreceptors and retinal pigment epithelium via intravitreal injection. A nucleolin binding aptamer, AS1411, was biotinylated and complexed with traptavidin and utilized as a platform for the delivery of GFP or X-linked inhibitor of apoptosis (XIAP) proteins by intravitreal injection in BALB/c mice. Retinal sections were analyzed for uptake of proteins in the retina. Apoptosis was induced by intravitreal injection of N-methyl-D-aspartate (NMDA). Retinas were harvested for analysis of TUNEL and caspase 3/7 activity. Intravitreal injection of AS1411-directed GFP or XIAP complexes enabled delivery of these proteins into ganglion cells, photoreceptors and retinal pigment epithelium in vivo. AS1411-XIAP complexes conferred significant protection to cells in the outer and inner nuclear layers following NMDA induced apoptosis. A concomitant decrease in activity of Caspase 3/7 was observed in eyes injected with the AS1411-XIAP complex. In conclusion, AS1411 can be used as a platform for the delivery of therapeutic proteins into retinal cells. This approach can potentially be utilized to introduce a large variety of therapeutically relevant proteins that are previously well characterized to maintain the structural integrity and function of retina, thus, preventing vision loss due to ocular trauma or inherited retinal degeneration.

Circular RNA VMA21 protects against intervertebral disc degeneration through targeting miR-200c and X linked inhibitor-of-apoptosis protein

OBJECTIVES

Circular RNAs (circRNAs) have been proven to function as competing endogenous RNAs to interact with microRNAs (miRNAs) and influence the expression of miRNA target mRNAs. In this study, we investigated whether circRNAs could act as competing endogenous RNAs to regulate the pathological process of intervertebral disc degeneration (IVDD).

METHODS

The role and mechanism of a circRNA, circVMA21, in IVDD were explored in nucleus pulposus (NP) cells and degenerative NP tissues from patients and rat models. The interaction between circVMA21 and miR-200c as well as the target mRNA, X linked inhibitor-of-apoptosis protein (XIAP), was examined.

RESULTS

The decreased expression of XIAP in the inflammatory cytokines-treated NP cells and the degenerative NP tissues was directly associated with excessive apoptosis and imbalance between anabolic and catabolic factors of extracellular matrix. miR-200c regulated NP cell viability and functions through inhibiting XIAP. circVMA21 acted as a sponge of miR-200c and functioned in NP cells through targeting miR-200c and XIAP. Intradiscal injection of circVMA21 alleviated IVDD in the rat model.

CONCLUSIONS

CircVMA21 could alleviate inflammatory cytokines-induced NP cell apoptosis and imbalance between anabolism and catabolism of extracellular matrix through miR-200c-XIAP pathway. It provides a potentially effective therapeutic strategy for IVDD.

Effects of Recombinant Circularly Permuted Tumor Necrosis Factor (TNF)-Related Apoptosis-Inducing Ligand (TRAIL) (Recombinant Mutant Human TRAIL) in Combination with 5-Fluorouracil in Human Colorectal Cancer Cell Lines HCT116 and SW480

Background

Circularly permuted tumor necrosis factor-related apoptosis-inducing ligand, a mutant form of tumor necrosis factor-related apoptosis-inducing ligand, is an effective antitumor cytokine. However, its antitumor effect in colorectal cancer is unclear. This study assessed the antitumor effect of circularly permuted tumor necrosis factor-related apoptosis-inducing ligand alone or with 5-fluorouracil in colorectal cancer cells in vitro and explored the underlying mechanisms.

Material/Methods

We used the (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay to analyze cell proliferation inhibition. The apoptotic effects of circularly permuted tumor necrosis factor-related apoptosis-inducing ligand, 5-fluorouracil, or both in human colorectal cancer cells were evaluated using flow cytometry. Furthermore, the levels of apoptosis-related proteins were examined by Western blotting.

Results

Compared to either agent alone, cotreatment with 5-fluorouracil and circularly permuted tumor necrosis factor-related apoptosis-inducing ligand showed obvious antitumor effects and induced significant apoptosis of colorectal cancer cells. 5-Fluorouracil enhanced circularly permuted tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis by increasing death receptor 4 and 5 levels in HCT116 cells, but only of death receptor 4 in SW480 cells. Moreover, 5-fluorouracil plus circularly permuted tumor necrosis factor-related apoptosis-inducing ligand increased apoptosis-related protein levels such as cleaved caspase-3, caspase-8, and poly-ADP-ribose polymerase and downregulated that of the survival protein B-cell lymphoma-extra-large. Pretreatment with the pan-caspase inhibitor, z-VAD-FMK, attenuated the caspase-dependent apoptosis induced by circularly permuted tumor necrosis factor-related apoptosis-inducing ligand alone or combined with 5-fluorouracil.

Conclusions

Cotreatment with 5-fluorouracil and circularly permuted tumor necrosis factor-related apoptosis-inducing ligand showed enhanced antitumor effects on colorectal cancer cells.

Necroptosis Execution Is Mediated by Plasma Membrane Nanopores Independent of Calcium

Necroptosis is a form of regulated necrosis that results in cell death and content release after plasma membrane permeabilization. However, little is known about the molecular events responsible for the disruption of the plasma membrane. Here, we find that early increase in cytosolic calcium in TNF-induced necroptosis is mediated by treatment with a Smac mimetic via the TNF/RIP1/TAK1 survival pathway. This does not require the activation of the necrosome and is dispensable for necroptosis. Necroptosis induced by the activation of TLR3/4 pathways does not trigger early calcium flux. We also demonstrate that necroptotic plasma membrane rupture is mediated by osmotic forces and membrane pores around 4 nm in diameter. This late permeabilization step represents a hallmark in necroptosis execution that is cell and treatment independent and requires the RIP1/RIP3/MLKL core. In support of this, treatment with osmoprotectants reduces cell damage in an in vivo necroptosis model of ischemia-reperfusion injury.

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Early calcium signaling in TSZ necroptosis correlates with cellular levels of cIAP1/2

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Calcium flux is induced by a Smac mimetic and is dispensable for necroptosis execution

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Pores ∼4 nm in diameter mediate final plasma membrane disruption in necroptosis

TRADD mediates the tumor necrosis factor-induced apoptosis of L929 cells in the absence of RIP3

Receptor-interacting protein kinase 3 (RIP3) is a critical initiator in mediating necroptosis induced by tumor necrosis factor alpha (TNFα) in L929 cells, so knockdown of RIP3 inhibits TNFα-induced L929 cell necroptosis. However, RIP3 knockdown was shown to switch TNFα-induced necroptosis to apoptosis in L929 cells in other studies. Therefore, whether RIP3 knockdown blocks the TNFα-induced death of L929 cells is controversial. In this study, TNFα activated caspase pathway and induced cell death in RIP3 knockdown L929 cells, and the RIP3-independent cell death had been blocked by Z-VAD-FMK (pan-caspase inhibitor) or caspase 8 knockdown, demonstrating that RIP3 knockdown switched TNFα-induced necroptosis to caspase-dependent apoptosis. Although both TNF receptor type 1-associated death domain protein (TRADD) and RIP1 have been reported to mediate TNFα-induced apoptosis, the knockdown of TRADD, but not RIP1, suppressed TNFα-induced activation of the caspase pathway and subsequent apoptosis in RIP3 knockdown L929 cells. In addition, TRADD bound and activated caspase 8 during the RIP3-independent apoptosis process, indicating that TRADD initiates RIP3-independent apoptosis by activating the caspase pathway. Collectively, we identified the target and mechanism underlying RIP3-independent apoptosis and elucidated the coordinated roles of RIP3 and TRADD in mediating the programmed cell death of L929 cells following TNFα stimulation.

Porphyromonas gingivalis Differentially Modulates Apoptosome Apoptotic Peptidase Activating Factor 1 in Epithelial Cells and Fibroblasts

Porphyromonas gingivalis is able to invade and modulate host-immune response to promote its survival. This bacterium modulates the cell cycle and programed cell death, contributing to periodontal lesion worsening. Several molecular pathways have been identified as key triggers of apoptosis, including apoptosome apoptotic peptidase activating factor 1 (APAF-1). Apaf-1 and X-linked inhibitor of apoptosis protein (Xiap) mRNA were differentially expressed between gingival samples harvested from human healthy and chronic periodontitis tissues (Apaf-1, 19.2-fold; caspase-9, 14.5-fold; caspase-3, 6.8-fold; Xiap: 2.5-fold in chronic periodontitis) (P < 0.05), highlighting their potential role in periodontitis. An increased proteic expression of APAF-1 was also observed in a murine experimental periodontitis model induced by P. gingivalis-soaked ligatures. In vitro, it was observed that P. gingivalis targets APAF-1, XIAP, caspase-3, and caspase-9, to inhibit epithelial cell death at both mRNA and protein levels. Opposite effect was observed in fibroblasts in which P. gingivalis increased cell death and apoptosis. To assess if the observed effects were associated to APAF-1, epithelial cells and fibroblasts were transfected with siRNA targeting Apaf-1. Herein, we confirmed that APAF-1 is targeted by P. gingivalis in both cell types. This study identified APAF-1 apoptosome and XIAP as intracellular targets of P. gingivalis, contributing to the deterioration of periodontal lesion through an increased persistence of the bacteria within tissues and the subversion of host-immune response.

Heterologous expression of anti-apoptotic human 14-3-3β/α enhances iron-mediated programmed cell death in yeast

The induction of Programmed Cell Death (PCD) requires the activation of complex responses involving the interplay of a variety of different cellular proteins, pathways, and processes. Uncovering the mechanisms regulating PCD requires an understanding of the different processes that both positively and negatively regulate cell death. Here we have examined the response of normal as well as PCD resistant yeast cells to different PCD inducing stresses. As expected cells expressing the pro-survival human 14-3-3β/α sequence show increased resistance to numerous stresses including copper and rapamycin. In contrast, other stresses including iron were more lethal in PCD resistant 14-3-3β/α expressing cells. The increased sensitivity to PCD was not iron and 14-3-3β/α specific since it was also observed with other stresses (hydroxyurea and zinc) and other pro-survival sequences (human TC-1 and H-ferritin). Although microscopical examination revealed little differences in morphology with iron or copper stresses, cells undergoing PCD in response to high levels of prolonged copper treatment were reduced in size. This supports the interaction some forms of PCD have with the mechanisms regulating cell growth. Analysis of iron-mediated effects in yeast mutant strains lacking key regulators suggests that a functional vacuole is required to mediate the synergistic effects of iron and 14-3-3β/α on yeast PCD. Finally, mild sub-lethal levels of copper were found to attenuate the observed inhibitory effects of iron. Taken together, we propose a model in which a subset of stresses like iron induces a complex process that requires the cross-talk of two different PCD inducing pathways.

XIAP 3'-untranslated region serves as a competitor for HMGA2 by arresting endogenous let-7a-5p in human hepatocellular carcinoma

X-linked inhibitor of apoptosis protein functions as an intrinsic regulator of apoptosis by inhibition of caspase activity and possesses a pivotal role in human cancer development and progression. A growing body of literature has demonstrated that microRNAs lead to the degradation or translational repression of messenger RNAs by binding to the non-coding region of messenger RNA at the 3'-untranslated region. Here, we revealed that the expression of HMGA2 is upregulated with X-linked inhibitor of apoptosis protein after transfection of X-linked inhibitor of apoptosis protein 3'-untranslated region in hepatocellular carcinoma cells, suggesting that X-linked inhibitor of apoptosis protein 3'-untranslated region serves as a competitor for microRNAs and prevent the co-targeted messenger RNA, HMGA2, from being suppressed. We further identified that let-7a-5p could bind to both the X-linked inhibitor of apoptosis protein 3'-untranslated region and HMGA2 3'-untranslated region. Moreover, we demonstrated that the forced expression of X-linked inhibitor of apoptosis protein 3'-untranslated region increases the oncogenicity of hepatocellular carcinoma cells in vitro. Cell functional analyses were performed to examine the association of HMGA2 status and X-linked inhibitor of apoptosis protein 3'-untranslated region. We have also measured the functional readout of let-7a-5p and HMGA2, an assay often employed to provide substantial evidence for the effects of X-linked inhibitor of apoptosis protein 3'-untranslated region on hepatocellular carcinoma cells. In general, our findings suggest that X-linked inhibitor of apoptosis protein 3'-untranslated region serves as a competitive endogenous RNA for HMGA2 to activate hepatocellular carcinoma progression by arresting endogenous let-7a-5p.

MutY DNA Glycosylase Protects Cells From Tumor Necrosis Factor Alpha-Induced Necroptosis

Numerous studies have implied that mutY DNA glycosylase (MYH) is involved in the repair of post-replicative mispairs and plays a critical role in the base excision repair pathway. Recent in vitro studies have shown that MYH interacts with tumor necrosis factor receptor type 1-associated death domain (TRADD), a key effector protein of tumor necrosis factor receptor-1 (TNFR1) signaling. The association between MYH and TRADD is reversed during tumor necrosis factor alpha (TNF-α)- and camptothecin (CPT)-induced apoptosis, and enhanced during TNF-α-induced survival. After investigating the role of MYH interacts with various proteins following TNF-α stimulation, here, we focus on MYH and TRADD interaction functions in necroptosis and its effects to related proteins. We report that the level of the MYH and TRADD complex was also reduced during necroptosis induced by TNF-α and zVAD-fmk. In particular, we also found that MYH is a biologically important necrosis suppressor. Under combined TNF-α and zVAD-fmk treatment, MYH-deficient cells were induced to enter the necroptosis pathway but primary mouse embryonic fibroblasts (MEFs) were not. Necroptosis in the absence of MYH proceeds via the inactivation of caspase-8, followed by an increase in the formation of the kinase receptor- interacting protein 1 (RIP1)-RIP3 complex. Our results suggested that MYH, which interacts with TRADD, inhibits TNF-α necroptotic signaling. Therefore, MYH inactivation is essential for necroptosis via the downregulation of caspase-8. J. Cell. Biochem. 118: 1827-1838, 2017. © 2017 Wiley Periodicals, Inc.