Necroptosis as an alternative form of programmed cell death

Siwu decoction suppress myeloid-derived suppressor cells through tumour cells necroptosis to inhibit hepatocellular carcinoma

BACKGROUND

Human hepatocellular carcinoma (HCC) acquired resistance to anti-cancer agents due to the presence of immunosuppressive tumour microenvironment (TME) established by the interaction between tumour cells and immune populations. New treatment targeting the interaction is urgently needed and clinically beneficial to patients with HCC. This study aims to explore the anti-tumour effect of a Traditional Chinese Medicine formula Siwu Decoction (SWD) and its potential mechanism.

MATERIALS AND METHODS

The chemical profile of SWD was determined by high-performance liquid chromatography coupled with mass spectrometry. In vitro and in vivo effects of SWD in regressing HCC were assessed. The role of myeloid-derived suppressor cells (MDSCs) in mediating SWD-induced HCC inhibition was determined by adoptive transfer assay. The regulation of SWD-induced interaction between HCC cells and MDSCs was also confirmed both in vitro and in vivo.

RESULTS

SWD dose-dependent inhibited the HCC growth and lung metastasis in an orthotopic growth tumour in mice, without significant toxicity and adverse side effect. SWD induced necroptosis in HCC cells, but did not directly inhibit in vitro culture of MDSCs, instead, SWD-treated HCC cell culture supernatant suppressed MDSCs by inducing its cell apoptosis. The necroptotic response of HCC cells can also suppress the MDSCs population in the TME without reducing circulating MDSCs infiltration into the tumours. Adoptive transfer of MDSCs recovered tumour growth and lung metastasis of HCC in SWD-treated mice. In HCC cells, SWD induced a necroptotic response, and blockade of necroptotic response in HCC cells recovered the MDSCs population in vitro and in vivo, and restored tumour growth and lung metastasis in SWD-treated mice. A combination of SWD improves the anti-HCC efficacy of sorafenib without inducing adverse side effects. Albiflorin, the effective compound of SWD, its anti-HCC manner has been verified to be consistent with that of SWD.

CONCLUSION

Our study observed for the first time that SWD can suppress HCC by regulating MDSCs through necroptosis of tumour cells in the TME. The main effective compound of SWD, albiflorin can be a potential adjuvant therapy in the clinical management of human HCC.

Ginsenoside Rg3 improves microcystin-induced cardiotoxicity through the miR-128-3p/MDM4 axis

Microcystin (MC) is the byproduct of cyanobacteria metabolism that is associated with oxidative stress and heart damage. This study aimed to investigate the effect of ginsenoside Rg3 on MC-induced cardiotoxicity. A mouse model of myocardial infarction was constructed by oral MC administration. H9C2 cells were used for in vitro analysis. Cellular oxidative stress, apoptosis, and the relationship between miR-128-3p and double minute 4 protein (MDM4) were analyzed. MiR-128-3p expression was upregulated in vitro and in vivo after MC treatment, which was downregulated after Rg3 treatment. Left ventricular ejection fraction (LVEF) and left ventricular systolic pressure (LVSP) were increased and left ventricular end-diastolic pressure (LVEDP) was decreased after Rg3 treatment. Moreover, Rg3 alleviated MC-induced pathological changes and apoptosis in myocardial tissues. Meanwhile, Rg3 treatment decreased the lactate dehydrogenase (LDH) and malondialdehyde (MDA) levels and inhabited cell apoptosis and oxidative stress in MC-treated myocardial cells. MiR-128-3p overexpression attenuated the protective effect of Rg3 on MC-induced cardiotoxicity. MiR-128-3p negatively regulated MDM4 expression. This study revealed that Rg3 alleviated MC-induced cardiotoxicity through the miR-128-3p/MDM4 axis, which emphasized the potential of Rg3 as a therapeutic agent for MC-induced cardiotoxicity, and miR-128-3p as a target for the Rg3 therapy.

Godanti bhasma (anhydrous CaSO4) induces massive cytoplasmic vacuolation in mammalian cells: A model for phagocytosis assay

Phagocytosis is an essential physiological mechanism; its impairment is associated with many diseases. A highly smart particle is required for understanding detailed sequential cellular events in phagocytosis. Recently, we identified an Indian traditional medicine named Godanti Bhasma (GB), a bioactive calcium sulfate particle prepared by thermo-transformation ofgypsum. Thermal processing of the gypsum transforms its native physicochemical properties by removing water molecules into the anhydrous GB, which was confirmed by Raman and FT-IR spectroscopy. GB particle showed a 0.5-5 µm size range and a neutral surface charge. Exposure of mammalian cells to GB particles showed a rapid cellular uptake through phagocytosis and induced massive cytoplasmic vacuolation in cells. Interestingly, no cellular uptake and cytoplasmic vacuolation were observed with the parent gypsum particle. The presence of the GB particles in intra-vacuolar space was confirmed using FESEM coupled with EDX. Flow cytometry analysis and live tracking of GB-treated cells showed particle internalization, vacuole formation, particle dissolution, and later vacuolar turnover. Quantification of GB-induced vacuolation was done using neutral red uptake assay in cells. Treatment of lysosomal inhibitors (BFA1 or CQ) with GB could not induce vacuolation, suggesting the requirement of an acidic environment for the vacuolation. In the mimicking experiment, GB particle dissolution in acidic cell-free solution suggested that degradation of GB occurs by acidic pH inside the cell vacuole. Vacuole formation generally accompanies with cell death, whereas GB-induced massive vacuolation does not cause cell death. Moreover, the cell divides and proliferates with the vacuolar process, intra-vacuolar cargo degradation, and eventually vacuolar turnover. Taken together, the sequential cellular events in this study suggest that GB can be used as a smart particle for phagocytosis assay development in animal cells.

Both TREM2-dependent macrophages and Kupffer cells play a protective role in APAP-induced acute liver injury

The inflammatory response is a significant factor in acetaminophen (APAP)-induced acute liver injury. And it can be mediated by macrophages of different origins. However, whether Kupffer cells and mononuclear-derived macrophages play an injury or protective role in APAP hepatotoxicity is still unclear. In this study, C57/BL6N mice were performed to establish the APAP acute liver injury model. Intervention experiments were also carried out using clodronate liposomes or TREM2 knockout. We found that APAP overdose triggered the activation of inflammatory factors and enhanced the expression of the RIPK1-MLKL pathway in mice's livers. Moreover, our study showed that inflammation-related protein expression was increased after clodronate liposome administration or TREM2 knockout. The RIPK1-MLKL-mediated necroptosis was also significantly activated after the elimination of Kupffer cells or the inhibition of mononuclear-derived macrophages. More importantly, clodronate liposomes treatment and TREM2 deficiency all worsen APAP-induced liver damage in mice. In conclusion, the results indicate that Kupffer cells and mononuclear macrophages play a protective role in APAP-induced liver injury by regulating necroptosis. Therefore, macrophages hold as a potential therapeutic target for APAP-induced liver damage.

Knockdown of iPLA2γ enhances cisplatin-induced apoptosis by increasing ROS-dependent peroxidation of mitochondrial phospholipids in bladder cancer cells

Cisplatin (CDDP) is a platinum-based drug with anti-cancer activity and is widely used as a standard therapy for bladder cancer. It is well known that CDDP causes cell death by increasing the generation of reactive oxygen species (ROS) and lipid peroxidation, but the mechanism of its anti-cancer effects has not been fully elucidated. There are still some problems such as chemoresistance in CDDP therapy. In the present study, we found the expression of Ca2+-independent phospholipase A2γ (iPLA2γ), which has been reported to regulate cellular redox homeostasis by inhibiting lipid peroxide accumulation, in human bladder cancer tissues. Thus, we investigated the effect of iPLA2γ knockdown on CDDP-induced bladder cancer cell death. As a result, we found that iPLA2γ knockdown significantly enhanced CDDP-induced apoptosis, intracellular and mitochondrial ROS production, cytochrome c release and caspase activation in bladder cancer cells. Moreover, mitochondrial membrane potential was decreased and peroxidation of mitochondrial phospholipids was increased by iPLA2γ knockdown. It was also shown that co-treatment of bromoenol lactone, an iPLA2 inhibitor, increased CDDP-induced apoptosis. These results indicated that iPLA2γ plays an important role in protecting bladder cancer cells from CDDP-induced apoptosis, and that iPLA2γ inhibitors might represent a novel strategy in CDDP-based multi-drug therapy.

FASLG as a Key Member of Necroptosis Participats in Acute Myocardial Infarction by Regulating Immune Infiltration

Background

Acute myocardial infarction (AMI) is a major cause of human health risk. Necroptosis is a newly and recently reported mode of cell death, whose role in AMI has not been fully elucidated. This study aimed to search for necroptosis biomarkers associated with the occurrence of AMI and to explore their possible molecular mechanisms through bioinformatics analysis.

Methods

The dataset GSE48060 was used to perform weighted gene co-expression network analysis (WGCNA) and differential analysis. Key modules, differential genes, and necroptosis-related genes (NRGs) were intersected to obtain candidate biomarkers. Groups were classified and differentially analyzed according to the expression of the key biomarker. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, gene set enrichment analysis (GSEA), and construction of protein-protein interaction (PPI) networks are performed on differentially expressed genes (DEGs). Finally, CIBERSORT was used to assess immune cell infiltration in AMI and the correlation of key biomarkers with immune cells. Immune cell infiltration analysis revealed the correlation between FASLG and multiple screened immune cells.

Results

WGCNA determined that the MEsaddlebrown module was the most significantly associated with AMI. Intersecting it with DEGs as well as NRGs, we obtained two key genes, FASLG and IFNG. But only FASLG showed statistically significant differences between the AMI group and the normal control group. Further analysis suggested that the down-regulation of FASLG may exert its function through the regulation of the central genes CD247 and YES1. Furthermore, FASLG was positively correlated with T-cell CD4 memory activation and T-cell gamma delta, and negatively correlated with macrophage M0.

Conclusion

In conclusion, FASLG and its regulatory genes CD247 and YES1 might be involved in the development of AMI by regulating immune cell infiltration. FASLG might be a potential biomarker for AMI and provides a new direction for the diagnosis of AMI.

Mitochondria-Targeting Metallodrugs for Cancer Therapy: Perspectives from Cell Death Modes

Mitochondria, recognized as the cellular powerhouses, are indispensable organelles responsible for crucial cellular processes, such as energy metabolism, material synthesis, and signaling transduction. Their intricate involvement in a broad spectrum of diseases, particularly cancer, has propelled the exploration of mitochondria-targeting treatment as a promising strategy for cancer therapy. Since the groundbreaking discovery of cisplatin, the trajectory of research on the development of metal complexes have been marked by continuous advancement, giving rise to a diverse array of metallodrugs characterized by variations in ligand types, metal center properties, and oxidation states. By specifically targeting mitochondria, these metallodrugs exhibit the remarkable ability to elicit various programmed cell death pathways, encompassing apoptosis, autophagy, and ferroptosis. This review primarily focuses on recent developments in transition metal-based mitochondria-targeting agents, offering a comprehensive exploration of their capacity to induce distinct cell death modes. The aim is not only to disseminate knowledge but also to stimulate an active field of research toward new clinical applications and novel anticancer mechanisms.

Identification and Validation of a Necroptosis-Related Prognostic Model in Tumor Recurrence and Tumor Immune Microenvironment in Breast Cancer Management

Background

Breast cancer is the leading cause of cancer-related death in women. Necroptosis, a form of programmed necrotic cell death, occurs in many solid tumors, including breast cancer, and influences anti-tumor immunity. The role of necroptosis in managing breast cancer recurrence remains unclear.

Methods

Gene expression profiles and clinical data of breast cancer patients were obtained from the GEO (GSE20685, GSE21653, GSE25055) and TCGA databases. Data analysis and visualization were performed using R. Unsupervised Consensus Clustering and LASSO-COX regression stratified breast cancer patients. GO, KEGG, GSVA, ESTIMATE, and ROC analyses were used to investigate necroptotic signatures. In vitro and in vivo experiments validated necroptosis's role in breast cancer immunity.

Results

The potential function of necroptotic signature in immunity was first indicated with GO analysis in BRCA cohort. Next, two prognostic models based on the necroptotic profiles both suggested a link between low-risk group with a particular necroptotic immune signature. And a variety of immune cells and immune pathways were shown to be positively associated with a patient's risk score. As an altered immune checkpoint pattern was observed after regulating necroptotic genes, where TIM-3 and LAGLS9 elevated significantly in low-risk group, further validation in vitro and in vivo demonstrated that manipulating a subset of necroptotic gene set could sensitize tumor response to the co-blockade immunotherapy of anti-TIM-3 and anti-PD-1.

Conclusion

We demonstrated two strategies to stratify breast cancer patients based on their necroptotic profiles and showed that necroptotic signature could assign patients with different tumor immune microenvironment patterns and different recurrence-related prognosis. A subset of necroptotic gene set, composed of TLR3, RIPK3, NLRP3, CASP1, ALDH2 and EZH2, was identified as a biomarker set for predicting immunotherapy-response and recurrence-related prognosis. Targeting necroptosis could helpfacilitate the development of novel breast cancer treatments and tailor personalized medical treatment.

Necroptosis in recurrent implantation failure: A bioinformatics analysis of key genes and therapeutic targets

Recurrent implantation failure (RIF), a major issue in assisted reproductive technology (ART), may be influenced by necroptosis, a form of cell death linked to several diseases. This study was aimed at investigating the involvement of necroptosis in RIF. Using RNA-sequencing data from the Gene Expression Omnibus database, we identified differentially expressed necroptosis-related genes (DENRGs) in RIF patients compared with those in controls. Functional enrichment, protein-protein interaction (PPI) networks, and transcription factor (TF) regulatory networks were analyzed to identify key genes. Immune cell infiltration was analyzed using the single-sample gene set enrichment analysis (ssGSEA) algorithm. Finally, potential therapeutic drugs targeting key genes were explored using a Drug Gene Interaction Database. In total, 20 DENRGs associated with RIF were identified, with a focus on 6 key genes (MLKL, FASLG, XIAP, CASP1, BIRC3, and TLR3) implicated in necroptosis and immune processes. These genes were used to develop a predictive model for RIF, which was validated in 2 datasets. The model and TF network analysis underscored the importance of TLR3. Immune infiltration analysis showed reduced levels of 16 immune cells in RIF patients, highlighting immune system alterations. Several drugs targeting CASP1, such as nivocasan and emricasan, were identified as potential treatments. The study sheds light on the role of necroptosis in RIF, identifying key genes and immune alterations that could serve as biomarkers and therapeutic targets. These findings pave the way for future experimental research and clinical applications targeting necroptosis in RIF treatment.

The importance of murine phospho-MLKL-S345 in situ detection for necroptosis assessment in vivo

Necroptosis is a caspase-independent modality of cell death implicated in many inflammatory pathologies. The execution of this pathway requires the formation of a cytosolic platform that comprises RIPK1 and RIPK3 which, in turn, mediates the phosphorylation of the pseudokinase MLKL (S345 in mouse). The activation of this executioner is followed by its oligomerisation and accumulation at the plasma-membrane where it leads to cell death via plasma-membrane destabilisation and consequent permeabilisation. While the biochemical and cellular characterisation of these events have been amply investigated, the study of necroptosis involvement in vivo in animal models is currently limited to the use of Mlkl-/- or Ripk3-/- mice. Yet, even in many of the models in which the involvement of necroptosis in disease aetiology has been genetically demonstrated, the fundamental in vivo characterisation regarding the question as to which tissue(s) and specific cell type(s) therein is/are affected by the pathogenic necroptotic death are missing. Here, we describe and validate an immunohistochemistry and immunofluorescence-based method to reliably detect the phosphorylation of mouse MLKL at serine 345 (pMLKL-S345). We first validate the method using tissues derived from mice in which Caspase-8 (Casp8) or FADD are specifically deleted from keratinocytes, or intestinal epithelial cells, respectively. We next demonstrate the presence of necroptotic activation in the lungs of SARS-CoV-infected mice and in the skin and spleen of mice bearing a Sharpin inactivating mutation. Finally, we exclude necroptosis occurrence in the intestines of mice subjected to TNF-induced septic shock. Importantly, by directly comparing the staining of pMLKL-345 with that of cleaved Caspase-3 staining in some of these models, we identify spatio-temporal and functional differences between necroptosis and apoptosis supporting a role of RIPK3 in inflammation independently of MLKL versus the role of RIPK3 in activation of necroptosis.

The fate and function of non-coding RNAs during necroptosis

Necroptosis is a novel form of cell death which is activated when apoptotic cell death signals are disrupted. Accumulating body of observations suggests that noncoding RNAs, which are the lately discovered mystery of the human genome, are significantly associated with necroptotic signaling circuitry. The fate and function of miRNAs have been well documented in human disease, especially cancer. Recently, lncRNAs have gained much attention due to their diverse regulatory functions. Although available studies are currently based on bioinformatic analysis, predicted interactions desires further attention, as these hold significant promise and should not be overlooked. In the light of these, here we comprehensively review and discuss noncoding RNA molecules that play significant roles during execution of necroptotic cell death.

Mts1 (S100A4) and Its Peptide Demonstrate Cytotoxic Activity in Complex with Tag7 (PGLYRP1) Peptide

Receptors of cytokines are major regulators of the immune response. In this work, we have discovered two new ligands that can activate the TNFR1 (tumor necrosis factor receptor 1) receptor. Earlier, we found that the peptide of the Tag (PGLYRP1) protein designated 17.1 can interact with the TNFR1 receptor. Here, we have found that the Mts1 (S100A4) protein interacts with this peptide with a high affinity (Kd = 1.28 × 10-8 M), and that this complex is cytotoxic to cancer cells that have the TNFR1 receptor on their surface. This complex induces both apoptosis and necroptosis in cancer cells with the involvement of mitochondria and lysosomes in cell death signal transduction. Moreover, we have succeeded in locating the Mts1 fragment that is responsible for protein-peptide interaction, which highly specifically interacts with the Tag7 protein (Kd = 2.96 nM). The isolated Mts1 peptide M7 also forms a complex with 17.1, and this peptide-peptide complex also induces the TNFR1 receptor-dependent cell death. Molecular docking and molecular dynamics experiments show the amino acids involved in peptide binding and that may be used for peptidomimetics' development. Thus, two new cytotoxic complexes were created that were able to induce the death of tumor cells via the TNFR1 receptor. These results may be used in therapy for both cancer and autoimmune diseases.

MLKL regulates radiation-induced death in breast cancer cells: an interplay between apoptotic and necroptotic signals

Resistance to caspase-dependent apoptosis is often responsible for treatments failure in cancer. Necroptosis is a type of programmed necrosis that occurs under caspase-deficient conditions that could overcome apoptosis resistance. Our purpose was to investigate the interrelationship between apoptotic and necroptotic death pathways and their influence on the response of breast cancer cells to radiotherapy in vitro. Human BC cell lines MCF-7 and MDA-MB-231 were treated with ionizing radiation, and then several markers of apoptosis, necroptosis, and survival were assessed in the presence and absence of necroptosis inhibition. MLKL knockdown was achieved by siRNA transfection. Our main findings emphasize the role of necroptosis in cellular response to radiation represented in the dose- and time-dependent elevated expression of necroptotic markers RIPK1, RIPK3, and MLKL. Knockdown of necroptotic marker MLKL by siRNA led to a significant elevation in MDA-MB-231 and MCF-7 survival with a dose modifying factor (DMF) of 1.23 and 1.61, respectively. Apoptotic markers Caspase 8 and TRADD showed transitory or delayed upregulation, indicating that apoptosis was not the main mechanism by which cells respond to radiation exposure. Apoptotic markers also showed a significant elevation following MLKL knockdown, suggesting its role either as a secondary or death alternative pathway. The result of our study emphasizes the critical role of the necroptotic pathway in regulating breast cancer cells responses to radiotherapy and suggests a promising utilization of its key modulator, MLKL, as a treatment strategy to improve the response to radiotherapy.

ZBP1-mediated apoptosis and inflammation exacerbate steatotic liver ischemia/reperfusion injury

Steatotic donor livers are becoming more and more common in liver transplantation. However, the current use of steatotic grafts is less acceptable than normal grafts due to their higher susceptibility to ischemia/reperfusion (I/R) injury. To investigate the mechanism underlying the susceptibility of steatotic liver to I/R injury, we detected cell death markers and inflammation in clinical donor livers and animal models. We found that caspase-8-mediated hepatic apoptosis is activated in steatotic liver I/R injury. However, ablation of caspase-8 only slightly mitigated steatotic liver I/R injury without affecting inflammation. We further demonstrated that RIPK1 kinase induces both caspase-8-mediated apoptosis and cell death-independent inflammation. Inhibition of RIPK1 kinase significantly protects against steatotic liver I/R injury by alleviating both hepatic apoptosis and inflammation. Additionally, we found that RIPK1 activation is induced by Z-DNA binding protein 1 (ZBP1) but not the canonical TNF-α pathway during steatotic liver I/R injury. Deletion of ZBP1 substantially decreases the steatotic liver I/R injury. Mechanistically, ZBP1 is amplified by palmitic acid-activated JNK pathway in steatotic livers. Upon I/R injury, excessive reactive oxygen species trigger ZBP1 activation by inducing its aggregation independent of the Z-nucleic acids sensing action in steatotic livers, leading to the kinase activation of RIPK1 and the subsequent aggravation of liver injury. Thus, ZBP1-mediated RIPK1-driven apoptosis and inflammation exacerbate steatotic liver I/R injury, which could be targeted to protect steatotic donor livers during transplantation.

Photothermal therapy: a novel potential treatment for prostate cancer

Prostate cancer (PCa) is a leading cause of cancer-related death in men, and most PCa patients treated with androgen deprivation therapy will progress to metastatic castration-resistant prostate cancer (mCRPC) due to the lack of efficient treatment. Recently, lots of research indicated that photothermal therapy (PTT) was a promising alternative that provided an accurate and efficient prostate cancer therapy. A photothermic agent (PTA) is a basic component of PPT and is divided into organic and inorganic PTAs. Besides, the combination of PTT and other therapies, such as photodynamic therapy (PDT), immunotherapy (IT), chemotherapy (CT), etc., provides an more efficient strategy for PCa therapy. Here, we introduce basic information about PTT and summarize the PTT treatment strategies for prostate cancer. Based on recent works, we think the combination of PPT and other therapies provides a novel possibility for PCa, especially CRPC clinical treatment.

RIPK3 signaling and its role in regulated cell death and diseases

Receptor-interacting protein kinase 3 (RIPK3), a member of the receptor-interacting protein kinase (RIPK) family with serine/threonine protein kinase activity, interacts with RIPK1 to generate necrosomes, which trigger caspase-independent programmed necrosis. As a vital component of necrosomes, RIPK3 plays an indispensable role in necroptosis, which is crucial for human life and health. In addition, RIPK3 participates in the pathological process of several infections, aseptic inflammatory diseases, and tumors (including tumor-promoting and -suppressive activities) by regulating autophagy, cell proliferation, and the metabolism and production of chemokines/cytokines. This review summarizes the recent research progress of the regulators of the RIPK3 signaling pathway and discusses the potential role of RIPK3/necroptosis in the aetiopathogenesis of various diseases. An in-depth understanding of the mechanisms and functions of RIPK3 may facilitate the development of novel therapeutic strategies.

The 12-Membered TNFR1 Peptide, as Well as the 16-Membered and 6-Membered TNF Peptides, Regulate TNFR1-Dependent Cytotoxic Activity of TNF

Understanding the exact mechanisms of the activation of proinflammatory immune response receptors is very important for the targeted regulation of their functioning. In this work, we were able to identify the sites of the molecules in the proinflammatory cytokine TNF (tumor necrosis factor) and its TNFR1 (tumor necrosis factor receptor 1), which are necessary for the two-stage cytotoxic signal transduction required for tumor cell killing. A 12-membered TNFR1 peptide was identified and synthesized, interacting with the ligands of this receptor protein's TNF and Tag7 and blocking their binding to the receptor. Two TNF cytokine peptides interacting with different sites of TNFR1 receptors were identified and synthesized. It has been demonstrated that the long 16-membered TNF peptide interferes with the binding of TNFR1 ligands to this receptor, and the short 6-membered peptide interacts with the receptor site necessary for the transmission of a cytotoxic signal into the cell after the ligands' interaction with the binding site. This study may help in the development of therapeutic approaches to regulate the activity of the cytokine TNF.

Oxytosis/Ferroptosis in Neurodegeneration: the Underlying Role of Master Regulator Glutathione Peroxidase 4 (GPX4)

Oxytosis/ferroptosis is an iron-dependent oxidative form of cell death triggered by lethal accumulation of phospholipid hydroperoxides (PLOOHs) in membranes. Failure of the intricate PLOOH repair system is a principle cause of ferroptotic cell death. Glutathione peroxidase 4 (GPX4) is distinctly vital for converting PLOOHs in membranes to non-toxic alcohols. As such, GPX4 is known as the master regulator of oxytosis/ferroptosis. Ferroptosis has been implicated in a number of disorders such as neurodegenerative diseases (amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD), etc.), ischemia/reperfusion injury, and kidney degeneration. Reduced function of GPX4 is frequently observed in degenerative disorders. In this study, we examine how diminished GPX4 function may be a critical event in triggering oxytosis/ferroptosis to perpetuate or initiate the neurodegenerative diseases and assess the possible therapeutic importance of oxytosis/ferroptosis in neurodegenerative disorders. These discoveries are important for advancing our understanding of neurodegenerative diseases because oxytosis/ferroptosis may provide a new target to slow the course of the disease.

Therapeutic potential of melatonin in targeting molecular pathways of organ fibrosis

Fibrosis, the excessive deposition of fibrous connective tissue in an organ in response to injury, is a pathological condition affecting many individuals worldwide. Fibrosis causes the failure of tissue function and is largely irreversible as the disease progresses. Pharmacologic treatment options for organ fibrosis are limited, but studies suggest that antioxidants, particularly melatonin, can aid in preventing and controlling fibrotic damage to the organs. Melatonin, an indole nocturnally released from the pineal gland, is commonly used to regulate circadian and seasonal biological rhythms and is indicated for treating sleep disorders. While it is often effective in treating sleep disorders, melatonin's anti-inflammatory and antioxidant properties also make it a promising molecule for treating other disorders such as organ fibrosis. Melatonin ameliorates the necrotic and apoptotic changes that lead to fibrosis in various organs including the heart, liver, lung, and kidney. Moreover, melatonin reduces the infiltration of inflammatory cells during fibrosis development. This article outlines the protective effects of melatonin against fibrosis, including its safety and potential therapeutic effects. The goal of this article is to provide a summary of data accumulated to date and to encourage further experimentation with melatonin and increase its use as an anti-fibrotic agent in clinical settings.

Integrated analysis of necroptosis related gene signature to predict clinical outcomes, immune status and drug sensitivity in lower grade Glioma

Background

The treatment of lower grade gliomas (LGG) is currently the most challenging dilemma in the management of intracranial tumors. Necroptosis is a type of programmed cell death that is closely associated with tumor progression, However, the role of necroptosis related genes in LGG is not yet well elucidated.

Methods

Online databases were used to obtain gene expression and clinical information. After gene differential expression analysis, a risk score model based on prognostic differentially expressed necroptosis-related genes (DENGs) were constructed to predict prognosis for LGG patients. The validity of the risk score model was then assessed with Kaplan-Meier survival curve. The prognostic DENGs included in the risk score model were then subjected to gene expression analysis, functional enrichment analysis, consensus clustering analysis, and single cell sequencing analysis. Finally, we investigated the correlation of the risk score and immune infiltration in LGG tumor microenvironment and drug sensitivity for LGG patients in different risk groups.

Results

A survival risk score model was constructed based on seven prognostic DENGs, which demonstrated satisfactory performance in predicting the prognosis of LGG patients. According to functional enrichment analyses, these seven DENGs may play a regulatory role in LGG tumorigenesis through several immune and metabolic pathways. LGG patients could be categorized into two clusters with distinct prognosis and clinicopathologic characteristics based on the expression of seven DENGs. Single-cell sequencing analysis demonstrated that the DENG signature was differentially expressed in various types of cells in LGG and may play a vital role in oncogenesis. Additionally, drug sensitivity analysis suggested that the seven-gene signature could guide clinical medication for LGG patients.

Conclusion

Our study developed a reliable necroptosis-related signature to predict the prognosis of LGG patients. This gene signature may also help estimate immune status and anti-cancer drug sensitivity in LGG patients. Our findings may pave the way to enhance our understanding of necroptosis in LGG.

In situ vaccination caused by diverse irradiation-driven cell death programs

Interest surrounding the effect of irradiation on immune activation has exponentially grown within the last decade. This includes work regarding mechanisms of the abscopal effect and the success achieved by combination of radiotherapy and immunotherapy. It is hypothesized that irradiation triggers the immune system to eliminate tumors by inducing tumor cells immunogenic cell death (ICD) in tumor cells. Activation of the ICD pathways can be exploited as an in situ vaccine. In this review, we provide fundamental knowledge of various forms of ICD caused by irradiation, describe the relationship between various cell death pathways and the immune activation effect driven by irradiation, and focus on the therapeutic value of exploiting these cell death programs in the context of irradiation. Furthermore, we summarize the immunomodulatory effect of different cell death programs on combinative radiotherapy and immunotherapy. In brief, differences in cell death programs significantly impact the irradiation-induced immune activation effect. Evaluating the transition between them will provide clues to develop new strategies for radiotherapy and its combination with immunotherapy.

Identification of TNFRSF21 as an inhibitory factor of osteosarcoma based on a necroptosis-related prognostic gene signature and molecular experiments

BACKGROUND

Osteosarcoma is one of the most common malignant bone tumors with bad prognosis. Necroptosis is a form of programmed cell death. Recent studies showed that targeting necroptosis was a new promising approach for tumor therapy. This study aimed to establish a necroptosis-related gene signature to evaluated prognosis and explore the relationship between necroptosis and osteosarcoma.

METHODS

Data from The Cancer Genome Atlas was used for developing the signature and the derived necroptosis score (NS). Data from Gene Expression Omnibus served as validation. Principal component analysis (PCA), Cox regression, receiver operating characteristic (ROC) curves and Kaplan-Meier survival analysis were used to assess the performance of signature. The association between the NS and osteosarcoma was analyzed via gene set enrichment analysis, gene set variation analysis and Pearson test. Single-cell data was used for further exploration. Among the genes that constituted the signature, the role of TNFRSF21 in osteosarcoma was unclear. Molecular experiments were used to explore TNFRSF21 function.

RESULTS

Our data revealed that lower NS indicated more active necroptosis in osteosarcoma. Patients with lower NS had a better prognosis. PCA and ROC curves demonstrated NS was effective to predict prognosis. NS was negatively associated with immune infiltration levels and tumor microenvironment scores and positively associated with tumor purity and stemness index. Single-cell data showed necroptosis heterogeneity in osteosarcoma. The cell communication pattern of malignant cells with high NS was positively correlated with tumor progression. The expression of TNFRSF21 was down-regulated in osteosarcoma cell lines. Overexpression of TNFRSF21 inhibited proliferation and motility of osteosarcoma cells. Mechanically, TNFRSF21 upregulated the phosphorylation levels of RIPK1, RIPK3 and MLKL to promote necroptosis in osteosarcoma.

CONCLUSIONS

The necroptosis prognostic signature and NS established in this study could be used as an independent prognostic factor, TNFRSF21 may be a necroptosis target in osteosarcoma therapy.

A Novel Necroptosis-Related Signature Can Predict Prognosis and Chemotherapy Sensitivity in Multiple Myeloma

BACKGROUND

Necroptosis is an inflammatory cell death mode, and its association with multiple myeloma (MM) remains unclear.

METHODS

This prospective study first analyzed the association between necroptosis-related signature as well as prognosis and chemotherapy sensitivity in MM using the necroptosis score. Consensus clustering was used to identify necroptosis-related molecular clusters. Least absolute shrinkage and selection operator analysis and multivariate Cox regression analysis were performed to establish the prognostic model of necroptosis-related genes (NRGs).

RESULTS

A high necroptosis score was associated with poor prognosis and abundant immune infiltration. Two molecular clusters (clusters A and B) significantly differed in terms of prognosis and tumor microenvironment. Cluster B had a worse prognosis and higher tumor marker pathway activity than cluster A. The risk score model based on four NRGs can accurately predict the prognosis of patients with MM, which was validated in two validation cohorts. Receiver operating characteristic curve analysis showed that the area under the curves of the risk score in predicting the 1-, 3-, and 5-year survival rates were 0.710, 0.758, and 0.834, respectively. Further, the activity of pathways related to proliferation and genetic regulation in the high-risk group significantly increased. The drug prediction results showed that the low-risk score group was more sensitive to bortezomib, cytarabine, and doxorubicin than the high-risk score group. Meanwhile, the high-risk score group was more sensitive to lenalidomide and vinblastine than the low-risk score group. Finally, the upregulation of model genes CHMP1A, FAS, JAK3, and HSP90AA1 in clinical samples collected from patients with MM was validated via real-time polymerase chain reaction.

CONCLUSION

A systematic analysis of NRGs can help identify potential necroptosis-related mechanisms and provide novel biomarkers for MM prognosis prediction, tumor microenvironment evaluation, and personalized treatment planning.

Homer1 ameliorates ischemic stroke by inhibiting necroptosis-induced neuronal damage and neuroinflammation

OBJECTIVE

Proinflammatory necroptosis is the main pathological mechanism of ischemic stroke. Homer scaffolding protein 1 (Homer1) is a postsynaptic scaffolding protein that exerts anti-inflammatory effects in most central nervous system diseases. However, the relationship between Homer1 and proinflammatory necroptosis in ischemic stroke remains unclear.

AIM

This study aimed to investigate the role of Homer1 in ischemia-induced necroptosis.

METHODS

C57BL/6 mice were used to establish a model of permanent middle cerebral artery occlusion model (pMCAO). Homer1 knockdown mice were generated using adeno-associated virus (AAV) infection to explore the role of Homer1 and its impact on necroptosis in pMCAO. Finally, Homer1 protein was stereotaxically injected into the ischemic cortex of Homer1flox/flox/Nestin-Cre +/- mice, and the efficacy of Homer1 was investigated using behavioral assays and molecular biological assays to explore potential mechanisms.

RESULTS

Homer1 expression peaked at 8 h in the ischemic penumbral cortex after pMCAO and colocalized with neurons. Homer1 knockdown promoted neuronal death by enhancing necroptotic signaling pathways and aggravating ischemic brain damage in mice. Furthermore, the knockdown of Homer1 enhanced the expression of proinflammatory cytokines. Moreover, injection of Homer1 protein reduced necroptosis-induced brain injury inhibited the expression of proinflammatory factors, and ameliorated the outcomes in the Homer1flox/flox/Nestin-Cre+/- mice after pMCAO.

CONCLUSIONS

Homer1 ameliorates ischemic stroke by inhibiting necroptosis-induced neuronal damage and neuroinflammation. These data suggested that Homer1 is a novel regulator of neuronal death and neuroinflammation.

Identifying the programmed cell death index of hepatocellular carcinoma for prognosis and therapy response improvement by machine learning: a bioinformatics analysis and experimental validation

Background

Despite advancements in hepatocellular carcinoma (HCC) treatments, the prognosis for patients remains suboptimal. Cumulative evidence suggests that programmed cell death (PCD) exerts crucial functions in HCC. PCD-related genes are potential predictors for prognosis and therapeutic responses.

Methods

A systematic analysis of 14 PCD modes was conducted to determine the correlation between PCD and HCC. A novel machine learning-based integrative framework was utilized to construct the PCD Index (PCDI) for prognosis and therapeutic response prediction. A comprehensive analysis of PCDI genes was performed, leveraging data including single-cell sequencing and proteomics. GBA was selected, and its functions were investigated in HCC cell lines by in vitro experiments.

Results

Two PCD clusters with different clinical and biological characteristics were identified in HCC. With the computational framework, the PCDI was constructed, demonstrating superior prognostic predictive efficacy and surpassing previously published prognostic models. An efficient clinical nomogram based on PCDI and clinicopathological factors was then developed. PCDI was intimately associated with immunological attributes, and PCDI could efficaciously predict immunotherapy response. Additionally, the PCDI could predict the chemotherapy sensitivity of HCC patients. A multilevel panorama of PCDI genes confirmed its stability and credibility. Finally, the knockdown of GBA could suppress both the proliferative and invasive capacities of HCC cells.

Conclusion

This study systematically elucidated the association between PCD and HCC. A robust PCDI was constructed for prognosis and therapy response prediction, which would facilitate clinical management and personalized therapy for HCC.

Necroptosis in human cancers with special emphasis on oral squamous cell carcinoma

Necroptosis is a type of caspase independent 'programmed or regulated' necrotic cell death that has a morphological resemblance to necrosis and mechanistic analogy to apoptosis. This type of cell death requires RIPK1, RIPK3, MLKL, death receptors, toll like receptors, interferons, and various other proteins. Necroptosis is implicated in plethora of diseases like rheumatoid arthritis, Alzheimer's disease, Crohn's disease, and head and neck cancers including oral squamous cell carcinoma. Oral carcinomas show dysregulation or mutation of necroptotic proteins, mediate antitumoral immunity, activate immune response and control tumor progression. Necroptosis is known to play a dual role (pro tumorigenic and anti-tumorigenic) in cancer progression and targeting this pathway could be an effective approach in cancer therapy. Necroptosis based chemotherapy has been proposed in malignancies, highlighting the importance of necroptotic pathway to overcome apoptosis resistance and serve as a "fail-safe" pathway to modulate cancer initiation, progression, and metastasis. However, there is dearth of information regarding the use of necroptotic cell death mechanism in the treatment of oral squamous cell carcinoma. In this review, we summarise molecular mechanism of necroptosis, and its protumorigenic and antitumorigenic role in cancers to shed light on the possible therapeutic significance of necroptosis in oral squamous cell carcinoma.

Oxidative stress and docosahexaenoic acid injury lead to increased necroptosis and ferroptosis in retinal pigment epithelium

Age-related macular degeneration (AMD) is a complex disease caused by different genetic and environmental risk factors leading to loss of cells in the central part of the retina. Oxidative stress appears to be an important environmental risk factor that contributes to both the initiation and progression of AMD. Retinal pigment epithelium (RPE) plays an important role in regulating oxidative stress in the retina and is one of the main retinal cell types affected in AMD. A main function of RPE is to phagocytose photoreceptor outer segments (POS) which are rich in the polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA), making this cell type potentially more susceptible to oxidative stress-induced lipid peroxidation which can lead to cell death. RPE is known to undergo necrotic cell death in response to oxidative stress. The aim of this study was to determine if DHA in POS can increase oxidative damage to RPE. It was found that RPE undergo increased lipid peroxidation and decreased cell viability when stressed with hydrogen peroxide in combination with DHA or POS. H2O2-induced oxidative stress was found to cause both ferroptosis and necroptosis. However, the ferroptosis regulator acyl-CoA synthetase long-chain family member 4 (ACSL4) was found to be downregulated in RPE exposed to H2O2 and this effect was exacerbated when the RPE cells were simultaneously treated with DHA. Together, these results show a response of RPE when stressed which will likely be overwhelmed under disease conditions such as AMD resulting in cell death.

Insight from Linker Investigations: Discovery of a Novel Phenylbenzothiazole Necroptosis Inhibitor Targeting Receptor-Interacting Protein Kinase 1 (RIPK1) from a Phenoxybenzothiazole Compound with Dual RIPK1/3 Targeting Activity

Necroptosis, a regulated cell death form, is a critical contributor in various inflammatory diseases. We previously identified a phenoxybenzothiazole SZM-610 as a RIPK1 and RIPK3 necroptosis inhibitor. We conducted extensive studies to investigate different chemical components' effects on antinecroptosis activity and RIPK1/3 activity. This study focused on replacing the linker in phenoxybenzothiazoles to assess its impact. Remarkably, compound 10, bearing a novel 3,2'-phenylbenzothiazole scaffold, exhibited fourfold more potent nanomolar activity than SZM-610. Unlike SZM-610, this compound inhibited RIPK1 (Kd = 17 nM) and eliminated RIPK3 inhibition at 5000 nM. Various linkages confirmed the 3,2'-phenylbenzothiazole superior potency. Moreover, this compound specifically inhibited necroptosis by inhibiting RIPK1, RIPK3, and MLKL phosphorylation. In a TNF-induced inflammatory model, it dose-dependently (1.25-5 mg/kg) protected mice from hypothermia and death, surpassing SZM-610's effectiveness. These findings highlight 3,2'-phenylbenzothiazole as a promising lead structure for developing drugs targeting necroptosis-related diseases.

Mitochondrial transplantation strategies in multifaceted induction of cancer cell death

Otto Warburg hypothesized that some cancer cells reprogram their metabolism, favoring glucose metabolism by anaerobic glycolysis (Warburg effect) instead of oxidative phosphorylation, mainly because the mitochondria of these cells were damaged or dysfunctional. It should be noted that mitochondrial apoptosis is decreased because of the dysfunctional mitochondria. Strategies like mitochondrial transplantation therapy, where functional mitochondria are transplanted to cancer cells, could increase cell death, such as apoptosis, because the intrinsic apoptosis mechanisms would be reactivated. In addition, mitochondrial transplantation is associated with the redox state, which could promote synergy with common anticancer treatments such as ionizing radiation, chemotherapy, or radiotherapy, increasing cell death due to the presence or decrease of oxidative stress. On the other hand, mitochondrial transfer, a natural process for sharing mitochondrial between cells, induces an increase in chemoresistance and invasiveness in cancer cells that receive mitochondria from cells of the tumor microenvironment (TME), which indicates an antitumor therapeutic target. This review focuses on understanding mitochondrial transplantation as a therapeutic outcome induced by a procedure in aspects including oxidative stress, metabolism shifting, mitochondrial function, auto-/mitophagy, invasiveness, and chemoresistance. It also explores how these mechanisms, such as apoptosis, necroptosis, and parthanatos, impact cell death pathways. Finally, it discusses the chemoresistance and invasiveness in cancer cells associated with mitochondria transfer, indicating an antitumor therapeutic target.

Profiling of small-molecule necroptosis inhibitors based on the subpockets of kinase-ligand interactions

Necroptosis is a highly regulated cell death (RCD) form in various inflammatory diseases. Receptor-interacting protein kinase 1 (RIPK1) and RIPK3 are involved in the pathway. Targeting the kinase domains of RIPK1 and/or 3 is a drug design strategy for related diseases. It is generally accepted that essential reoccurring features are observed across the human kinase domains, including RIPK1 and RIPK3. They present common N- and C-terminal domains that are built up mostly by α-helices and β-sheets, respectively. The current RIPK1/3 kinase inhibitors mainly interact with the kinase catalytic cleft. This article aims to present an in-depth profiling for ligand-kinase interactions in the crucial cleft areas by carefully aligning the kinase-ligand cocrystal complexes or molecular docking models. The similarity and differential structural segments of ligands are systematically evaluated. New insights on the adaption of the conserved and selective kinase domains to the diversity of chemical scaffolds are also provided. In a word, our analysis can provide a better structural requirement for RIPK1 and RIPK3 inhibition and a guide for inhibitor discovery and optimization of their potency and selectivity.

A novel necroptosis-related long non-coding RNA signature predicts prognosis and immune response in cervical cancer patients

BACKGROUND

Necroptosis has been linked to the development of tumors. Long non-coding RNAs (IncRNAs) have been identified as having a major role in numerous biological and pathological procedures. Despite this, the precise role that necroptosis-related lncRNAs (NRLs) have in cervical cancer (CC) and their potential for predicting its prognosis is still to a large extent unclear.

METHODS

Gene expression RNA-sequencing data, mutational data, and clinical profiles for 309 CC patients were obtained from the Cancer Genome Atlas (TCGA) database. The NRLs were then identified with Pearson correlation analysis followed by splitting of the patients into training and validation sets in a 3:2 ratio. Cox and LASSO regression models were performed to construct a cervical cancer prognostic signature based on NRLs. This 5-NRLs signature was then verified by Kaplan-Meier survival analysis, receiver operating characteristic (ROC) curve, and nomogram for prognostic prediction. Further, a correlation study between the risk score (RS) and immune cell infiltration, immune checkpoint molecules, tumor mutation burden (TMB), and the sensitivity of chemotherapy drug was conducted. To validate the 5-NRLs, a quantitative reverse transcription polymerase chain reaction (qRT-PCR) was finally performed.

RESULTS

The 5-NRLs signature was designed to accurately predict the prognosis of CC. It consists of AC092153.1, AC007686.3, LINC01281, AC009097.2, and RUSC1-AS1 and was found to be highly predictive using ROC and Kaplan-Meier curves. Furthermore, when analyzed through stratified survival analysis, it was confirmed to be an independent risk factor for prognosis. The nomogram and calibration curves further validated its clinical utility. Moreover, distinct differences between two risk groups were observed when examining immune cell infiltration, immune checkpoint molecules, somatic gene alterations and half-inhibitory concentration of anticancer drug.

CONCLUSIONS

The 5-NRLs signature is a novel and valuable tool for evaluating the prognosis of CC patients, providing clinicians with an informed decision-making framework to formulate tailored treatment plans for their patients.

p53 at the crossroad between mitochondrial reactive oxygen species and necroptosis

p53 is a redox-sensitive transcription factor that can regulate multiple cell death programs through different signaling pathways. In this review, we assess the role of p53 in the regulation of necroptosis, a programmed form of lytic cell death highly involved in the pathophysiology of multiple diseases. In particular, we focus on the role of mitochondrial reactive oxygen species (mtROS) as essential contributors to modulate necroptosis execution through p53. The enhanced generation of mtROS during necroptosis is critical for the correct interaction between receptor-interacting serine/threonine-protein kinase 1 (RIPK1) and 3 (RIPK3), two key components of the functional necrosome. p53 controls the occurrence of necroptosis by modulating the levels of mitochondrial H2O2 via peroxiredoxin 3 and sulfiredoxin. Furthermore, in response to increased levels of H2O2, p53 upregulates the long non-coding RNA necrosis-related factor, favoring the translation of RIPK1 and RIPK3. In parallel, a fraction of cytosolic p53 migrates into mitochondria, a process notably involved in necroptosis execution via its interaction with the mitochondrial permeability transition pore. In conclusion, p53 is located at the intersection between mtROS and the necroptosis machinery, making it a key protein to orchestrate redox signaling during necroptosis.

Novel, non-conventional pathways of necroptosis in the heart and other organs: Molecular mechanisms, regulation and inter-organelle interplay

Necroptosis, a cell death modality that is defined as a necrosis-like cell death depending on the receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like pseudokinase (MLKL), has been found to underlie the injury of various organs. Nevertheless, the molecular background of this cell loss seems to also involve, at least under certain circumstances, some novel axes, such as RIPK3-PGAM5-Drp1 (mitochondrial protein phosphatase 5-dynamin-related protein 1), RIPK3-CaMKII (Ca2+/calmodulin-dependent protein kinase II) and RIPK3-JNK-BNIP3 (c-Jun N-terminal kinase-BCL2 Interacting Protein 3). In addition, endoplasmic reticulum stress and oxidative stress via the higher production of reactive oxygen species produced by the mitochondrial enzymes and the enzymes of the plasma membrane have been implicated in necroptosis, thereby depicting an inter-organelle interplay in the mechanisms of this cell death. However, the role and relationship between these novel non-conventional signalling and the well-accepted canonical pathway in terms of tissue- and/or disease-specific prioritisation is completely unknown. In this review, we provide current knowledge on some necroptotic pathways being not directly associated with RIPK3-MLKL execution and report studies showing the role of respective microRNAs in the regulation of necroptotic injury in the heart and in some other tissues having a high expression of the pro-necroptotic proteins.

Dexamethasone-induced mitochondrial ROS-mediated inhibition of AMPK activity facilitates osteoblast necroptosis

Long-term or high-dose glucocorticoid use can lead to serious orthopedic complications, including femoral head necrosis. Both basic and clinical studies have shown that high doses dexamethasone (Dex) can directly induce osteoblasts death. This study investigated the mechanism underlying Dex induced osteoblast death. In this study, we showed that Dex induces osteoblast necroptosis, rather than apoptosis, through the inhibition of AMP-activated protein kinase (AMPK) activity. We also demonstrated that inactivation of AMPK-mediated necroptosis is through receptor-interacting protein kinase 3 (RIP3), but not RIP1. Furthermore, we found that Dex-induced necroptosis is dependent on mitochondrial reactive oxygen species (ROS) following with directly activation of RIP1 and inactivation of AMPK. These findings provide new insights into the mechanism of Dex-induced osteoblast death and may have implications for the development of new therapies for osteoporosis and other bone-related diseases.

Cancer Cachexia: Underlying Mechanisms and Potential Therapeutic Interventions

Cancer cachexia, a multifactorial metabolic syndrome developed during malignant tumor growth, is characterized by an accelerated loss of body weight accompanied by the depletion of skeletal muscle mass. This debilitating condition is associated with muscle degradation, impaired immune function, reduced functional capacity, compromised quality of life, and diminished survival in cancer patients. Despite the lack of the known capability of fully reversing or ameliorating this condition, ongoing research is shedding light on promising preclinical approaches that target the disrupted mechanisms in the pathophysiology of cancer cachexia. This comprehensive review delves into critical aspects of cancer cachexia, including its underlying pathophysiological mechanisms, preclinical models for studying the progression of cancer cachexia, methods for clinical assessment, relevant biomarkers, and potential therapeutic strategies. These discussions collectively aim to contribute to the evolving foundation for effective, multifaceted counteractive strategies against this challenging condition.

Zymosan A Improved Doxorubicin-Induced Ventricular Remodeling by Evoking Heightened Cardiac Inflammatory Responses and Healing in Mice

Background Doxorubicin-induced myocardial injury is reflected by the presence of vacuolization in both clinical and animal models. The lack of scar tissue to replace the vacuolizated cardiomyocytes indicates that insufficient cardiac inflammation and healing occurred following doxorubicin injection. Whether improved macrophage activity by zymosan A (zymosan) ameliorates doxorubicin-induced ventricular remodeling in mice is unknown. Methods and Results Mice were intravenously injected with vehicle or doxorubicin (5 mg/kg per week, 4 weeks), and cardiac structure and function were assessed by echocardiography. Two distinct macrophage subsets in hearts following doxorubicin injection were measured at different time points by flow cytometry. Moreover, cardiomyocyte vacuolization, capillary density, collagen content, and ventricular tensile strength were assessed. The therapeutic effect of zymosan (3 mg/kg, single injection) on doxorubicin-induced changes in the aforementioned parameters was determined. At the cellular level, the polarization of monocytes to proinflammatory or reparative macrophages were measured, with or without doxorubicin (0.25 and 0.5 μmol/L). Doxorubicin led to less proinflammatory and reparative macrophage infiltration in the heart in the early phase, with decreased cardiac capillary density and collagen III in the chronic phase. In cell culture, doxorubicin (0.5 μmol/L) repressed macrophage transition toward both proinflammatory and reparative subset. Zymosan enhanced both proinflammatory and reparative macrophage infiltration in doxorubicin-injected hearts, evoking a heightened acute inflammatory response. Zymosan alleviated doxorubicin-induced cardiomyocyte vacuolization in the chronic phase, in parallel with enhanced collagen content, capillary density, and ventricular tensile strength. Conclusions Zymosan improved cardiac healing and ameliorated doxorubicin-induced ventricular remodeling and dysfunction by activating macrophages at an optimal time.

Establishment of a novel signature to predict prognosis and immune characteristics of pancreatic cancer based on necroptosis-related long non-coding RNA

BACKGROUND

Necroptosis plays an important role in tumorigenesis and tumour progression. Long noncoding RNAs (lncRNAs) have been proven to be regulatory factors of necroptosis in various tumours. However, the real role of necroptosis-related lncRNAs (NRLs) and their potential to predict the prognosis of pancreatic cancer (PC) remain largely unclear. The goal of this study was to identify NRLs and create a predictive risk signature in PC, explore its prognostic predictive performance, and further assess immunotherapy and chemotherapy responses.

METHODS

RNA sequencing data, tumour mutation burden (TMB) data, and clinical profiles of 178 PC patients were downloaded from The Cancer Genome Atlas (TCGA) database. NRLs were identified using Pearson correlation analysis. Then, patients were divided into the training set and the validation set at a 1:1 ratio. Subsequently, Cox and LASSO regression analyses were conducted to establish a prognostic NRL signature in the training set and validation set. The predictive efficacy of the 5-NRL signature was assessed by survival analysis, nomogram, Cox regression, clinicopathological feature correlation analysis, and receiver operating characteristic (ROC) curve analysis. Furthermore, correlations between the risk score (RS) and immune cell infiltration, immune checkpoint molecules, somatic gene mutations, and anticancer drug sensitivity were analysed. Finally, we used quantitative reverse transcription polymerase chain reaction (qRT-PCR) to validate the 5-NRLs.

RESULTS

A 5-NRL signature was established to predict the prognosis of PC, including LINC00857, AL672291.1, PTPRN2-AS1, AC141930.2, and MEG9. The 5-NRL signature demonstrated a high degree of predictive power according to ROC and Kaplan‒Meier curves and was revealed to be an independent prognostic risk factor via stratified survival analysis. Nomogram and calibration curves indicated the clinical adaptability of the signature. Immune-related pathways were linked to the 5-NRL signature according to enrichment analysis. Additionally, immune cell infiltration, immune checkpoint molecules, somatic gene mutations and the half-maximal inhibitory concentration (IC50) of chemotherapeutic agents were significantly different between the two risk subgroups. These results suggested that our model can be used to evaluate the effectiveness of immunotherapy and chemotherapy, providing a potential new strategy for treating PC.

CONCLUSIONS

The novel 5-NRL signature is helpful for assessing the prognosis of PC patients and improving therapy options, so it can be further applied clinically.

Necroptosis in the sarcoma immune microenvironment: From biology to therapy

Apoptosis resistance remains a major obstacle to treatment failure in sarcoma. Necroptosis is a caspase-independent programmed cell death, investigated as a novel strategy to eradicate anti-apoptotic tumor cells. The process is mediated by the receptor-interacting proteins kinase family and mixed lineage kinase domain-like proteins, which is morphologically similar to necrosis. Recent studies suggest that necroptosis in the tumor microenvironment has pro- or anti-tumor effects on immune response and cancer development. Necroptosis-related molecules display a remarkable value in prognosis prediction and therapeutic response evaluation of sarcoma. Furthermore, the induction of tumor necroptosis has been explored as a feasible therapeutic strategy against sarcoma and to synergize with immunotherapy. This review discusses the dual roles of necroptosis in the immune microenvironment and tumor progression, and explores the potential of necroptosis as a new target for sarcoma treatment.

Inhibition of inflammatory factor TNF-α by ferrostatin-1 in microglia regulates necroptosis of oligodendrocyte precursor cells

OBJECTIVE

Inflammation of the surrounding environment is a major reason causing loss or injury of oligodendrocyte precursor cells (OPCs) in myelin-associated diseases. Lipopolysaccharide-activated microglia can release various inflammatory factors such as tumor necrosis factor-α (TNF-α). One of the ways of OPC death is necroptosis, which can be triggered by TNF-α, a death receptor ligand, by activating receptor-interacting protein kinase 1 (RIPK1)/RIPK3/mixed lineage kinase domain-like protein (MLKL) signaling pathway. This study investigated whether inhibiting microglia ferroptosis can decrease TNF-α release to alleviate OPC necroptosis.

METHODS

Lipopolysaccharide and Fer-1 stimulate BV2 cells. The expressions of GPX4 and TNF-α were detected by western blot and quantitative real-time PCR; malondialdehyde, glutathione, iron, and reactive oxygen species were measured by the assay kits. After lipopolysaccharide stimulation of BV2 cells, the supernatant was taken to culture OPC. The protein expression levels of RIPK1, p-RIPK1, RIPK3, p-RIPK3, MLKL, and p-MLKL were detected by western blot.

RESULTS

Lipopolysaccharide administration could induce ferroptosis in microglia by decreasing ferroptosis marker GPX4, while ferroptosis inhibitor Fer-1 could significantly increase GPX4 level. Fer-1 prevented oxidative stress and iron concentration elevation and alleviated mitochondrial damage in lipopolysaccharide-induced BV2 cells. The results revealed that Fer-1 downregulated the release of lipopolysaccharide-induced TNF-α in microglia and attenuated OPC necroptosis by significantly decreasing the expression levels of RIPK1, p-RIPK1, MLKL, p-MLKL, RIPK3, and p-RIPK3.

CONCLUSION

Fer-1 may be a potential agent for inhibiting inflammation and treating myelin-related diseases.

Unraveling the Complexity of Regulated Cell Death in Esophageal Cancer: from Underlying Mechanisms to Targeted Therapeutics

Esophageal cancer (EC) is the sixth most common and the seventh most deadly malignancy of the digestive tract, representing a major global health challenge. Despite the availability of multimodal therapeutic strategies, the existing EC treatments continue to yield unsatisfactory results due to their limited efficacy and severe side effects. Recently, knowledge of the subroutines and molecular mechanisms of regulated cell death (RCD) has progressed rapidly, enhancing the understanding of key pathways related to the occurrence, progression, and treatment of many types of tumors, including EC. In this context, the use of small-molecule compounds to target such RCD subroutines has emerged as a promising therapeutic strategy for patients with EC. Thus, in this review, we firstly discussed the risk factors and prevention of EC. We then outlined the established treatment regimens for patients with EC. Furthermore, we not only briefly summarized the mechanisms of five best studied subroutines of RCD related to EC, including apoptosis, ferroptosis, pyroptosis, necroptosis and autophagy, but also outlined the recent advances in the development of small-molecule compounds and long non-coding RNA (lncRNA) targeting the abovementioned RCD subroutines, which may serve as a new therapeutic strategy for patients with EC in the future.

Atezolizumab Induces Necroptosis and Contributes to Hepatotoxicity of Human Hepatocytes

Atezolizumab is an immune checkpoint inhibitor (ICI) targeting PD-L1 for treatment of solid malignancies. Immune checkpoints control the immune tolerance, and the adverse events such as hepatotoxicity induced by ICIs are often considered as an immune-related adverse event (irAE). However, PD-L1 is also highly expressed in normal tissues, e.g., hepatocytes. It is still not clear whether, targeting PD-L1 on hepatocytes, the atezolizumab may cause damage to liver cells contributing to hepatotoxicity. Here, we reveal a novel mechanism by which the atezolizumab induces hepatotoxicity in human hepatocytes. We find that the atezolizumab treatment increases a release of LDH in the cell culture medium of human hepatocytes (human primary hepatocytes and THLE-2 cells), decreases cell viability, and inhibits the THLE-2 and THLE-3 cell growth. We demonstrate that both the atezolizumab and the conditioned medium (T-CM) derived from activated T cells can induce necroptosis of the THLE-2 cells, which is underscored by the fact that the atezolizumab and T-CM enhance the phosphorylation of RIP3 and MLKL proteins. Furthermore, we also show that necrostatin-1, a necrosome inhibitor, decreases the amount of phosphorylated RIP3 induced by the atezolizumab, resulting in a reduced LDH release in the culture media of the THLE-2 cells. This finding is further supported by the data that GSK872 (a RIP3 inhibitor) significantly reduced the atezolizumab-induced LDH release. Taken together, our data indicate that the atezolizumab induces PD-L1-mediated necrosome formation, contributing to hepatotoxicity in PD-L1⁺-human hepatocytes. This study provides the molecular basis of the atezolizumab-induced hepatotoxicity and opens a new avenue for developing a novel therapeutic approach to reducing hepatotoxicity induced by ICIs.

Comprehensive analysis of necroptosis-related lncRNA signature with potential implications in tumor heterogeneity and prediction of prognosis in clear cell renal cell carcinoma

BACKGROUND

Necroptosis has been reported to play a critical role in occurrence and progression of cancer. The dysregulation of long non-coding RNAs (lncRNAs) is associated with the progression and metastasis of clear cell renal cell carcinoma (CCRCC). However, research on necroptosis-related lncRNAs in the tumor heterogeneity and prognosis of CCRCC is not completely unclear. This study aimed to analysis the tumor heterogeneity among CCRCC subgroups and construct a CCRCC prognostic signature based on necroptosis-related lncRNAs.

METHODS

Weighted gene co-expression network analysis (WGCNA) was performed to identify necroptosis-related lncRNAs. A preliminary classification of molecular subgroups was performed by non-negative matrix factorization (NMF) consensus clustering analysis. Comprehensive analyses, including fraction genome altered (FGA), tumor mutational burden (TMB), DNA methylation alterations, copy number variations (CNVs), and single nucleotide polymorphisms (SNPs), were performed to explore the potential factors for tumor heterogeneity among the three subgroups. Subsequently, we constructed a predictive signature by multivariate Cox regression. Nomogram, calibration curves, decision curve analysis (DCA), and time-dependent receiver-operating characteristics (ROC) were used to validate and evaluate the signature. Finally, immune correlation analyses, including immune-related signaling pathways, immune cell infiltration status and immune checkpoint gene expression level, were also performed.

RESULTS

Seven necroptosis-related lncRNAs were screened out by WGCNA, and three subgroups were classified by NMF consensus clustering analysis. There were significant differences in survival prognosis, clinicopathological characteristics, enrichments of immune-related signaling pathway, degree of immune cell infiltration, and expression of immune checkpoint genes in the various subgroups. Most importantly, we found that 26 differentially expressed genes (DEGs) among the 3 subgroups were not affected by DNA methylation alterations, CNVs and SNPs. On the contrary, these DEGs were associated with the seven necroptosis-related lncRNAs. Subsequently, the identified RP11-133F8.2 and RP11-283G6.4 by multivariate Cox regression analysis were involved in the risk model, which could serve as an independent prognostic factor for CCRCC. Finally, qRT-PCR confirmed the differential expression of the two lncRNAs.

CONCLUSIONS

These findings contributed to understanding the function of necroptosis-related lncRNAs in CCRCC and provided new insights of prognostic evaluation and optimal therapeutic strategy for CCRCC.

Molecular regulation and therapeutic implications of cell death in pulmonary hypertension

Pulmonary hypertension (PH) is a clinical and pathophysiological syndrome caused by changes in pulmonary vascular structure or function that results in increased pulmonary vascular resistance and pulmonary arterial pressure, and it is characterized by pulmonary endothelial dysfunction, pulmonary artery media thickening, pulmonary vascular remodeling, and right ventricular hypertrophy, all of which are driven by an imbalance between the growth and death of pulmonary vascular cells. Programmed cell death (PCD), different from cell necrosis, is an active cellular death mechanism that is activated in response to both internal and external factors and is precisely regulated by cells. More than a dozen PCD modes have been identified, among which apoptosis, autophagy, pyroptosis, ferroptosis, necroptosis, and cuproptosis have been proven to be involved in the pathophysiology of PH to varying degrees. This article provides a summary of the regulatory patterns of different PCD modes and their potential effects on PH. Additionally, it describes the current understanding of this complex and interconnected process and analyzes the therapeutic potential of targeting specific PCD modes as molecular targets.

Integrated Transcriptome and Metabolome Analysis Revealed the Causal Agent of Primary Bud Necrosis in 'Summer Black' Grape

Primary bud necrosis of grape buds is a physiological disorder that leads to decreased berry yield and has a catastrophic impact on the double cropping system in sub-tropical areas. The pathogenic mechanisms and potential solutions remain unknown. In this study, the progression and irreversibility patterns of primary bud necrosis in 'Summer Black' were examined via staining and transmission electron microscopy observation. Primary bud necrosis was initiated at 60 days after bud break and was characterized by plasmolysis, mitochondrial swelling, and severe damage to other organelles. To reveal the underlying regulatory networks, winter buds were collected during primary bud necrosis progression for integrated transcriptome and metabolome analysis. The accumulation of reactive oxygen species and subsequent signaling cascades disrupted the regulation systems for cellular protein quality. ROS cascade reactions were related to mitochondrial stress that can lead to mitochondrial dysfunction, lipid peroxidation causing damage to membrane structure, and endoplasmic reticulum stress leading to misfolded protein aggregates. All these factors ultimately resulted in primary bud necrosis. Visible tissue browning was associated with the oxidation and decreased levels of flavonoids during primary bud necrosis, while the products of polyunsaturated fatty acids and stilbenes exhibited an increasing trend, leading to a shift in carbon flow from flavonoids to stilbene. Increased ethylene may be closely related to primary bud necrosis, while auxin accelerated cell growth and alleviated necrosis by co-chaperone VvP23-regulated redistribution of auxin in meristem cells. Altogether, this study provides important clues for further study on primary bud necrosis.

V. J, Pal S, Nair BG, Kar R, Mishra N. Paraptosis: a unique cell death mode for targeting cancer

Programmed cell death (PCD) is the universal process that maintains cellular homeostasis and regulates all living systems' development, health and disease. Out of all, apoptosis is one of the major PCDs that was found to play a crucial role in many disease conditions, including cancer. The cancer cells acquire the ability to escape apoptotic cell death, thereby increasing their resistance towards current therapies. This issue has led to the need to search for alternate forms of programmed cell death mechanisms. Paraptosis is an alternative cell death pathway characterized by vacuolation and damage to the endoplasmic reticulum and mitochondria. Many natural compounds and metallic complexes have been reported to induce paraptosis in cancer cell lines. Since the morphological and biochemical features of paraptosis are much different from apoptosis and other alternate PCDs, it is crucial to understand the different modulators governing it. In this review, we have highlighted the factors that trigger paraptosis and the role of specific modulators in mediating this alternative cell death pathway. Recent findings include the role of paraptosis in inducing anti-tumour T-cell immunity and other immunogenic responses against cancer. A significant role played by paraptosis in cancer has also scaled its importance in knowing its mechanism. The study of paraptosis in xenograft mice, zebrafish model, 3D cultures, and novel paraptosis-based prognostic model for low-grade glioma patients have led to the broad aspect and its potential involvement in the field of cancer therapy. The co-occurrence of different modes of cell death with photodynamic therapy and other combinatorial treatments in the tumour microenvironment are also summarized here. Finally, the growth, challenges, and future perspectives of paraptosis research in cancer are discussed in this review. Understanding this unique PCD pathway would help to develop potential therapy and combat chemo-resistance in various cancer.

Understanding necroptosis and its therapeutic target for intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is a complex pathological condition associated with the development of low back pain. Despite numerous studies, the specific molecular mechanisms underlying IVDD remain unclear. At the cellular level, IVDD involves a series of changes, including cell proliferation, cell death, and inflammation. Of these, cell death plays a critical role in the progression of the condition. In recent years, necroptosis has been identified as a new form of programmed cell death (PCD). Necroptosis can be activated by ligands of death receptors, which then interact with RIPK1, RIPK3 and MLKL and lead to necrosome formation.. According to various previous studies, the necroptosis related pathway is activated in IVDD, and plays a significant role in the pathogenesis of IVDD. Furthermore, necroptosis may serve as a target for the IVDD treatment. Recently, several studies have reported the role of necroptosis in IVDD, but few studies have summarized the association between IVDD and necroptosis. The review gives a brief summary of the research progress of necroptosis, and discusses strategies and mechanisms that target necroptosis in IVDD. Lastly, matters needing attention in the necroptosis targeted therapy of IVDD are put forward at last. To the best of our knowledge, the review paper is the first one that integrates current research about the impact of necroptosis on IVDD, and contributes to the future therapy of IVDD from new perspectives.

RIPK1-dependent necroptosis promotes vasculogenic mimicry formation via eIF4E in triple-negative breast cancer

Necroptosis is a caspase-independent form of programmed cell death. Receptor interacting protein kinase 1 (RIPK1) is a key molecule in the initiation of necroptosis and the formation of the necrotic complex. Vasculogenic mimicry (VM) provides a blood supply to tumor cells that is not dependent on endothelial cells. However, the relationship between necroptosis and VM in triple-negative breast cancer (TNBC) is not fully understood. In this study, we found that RIPK1-dependent necroptosis promoted VM formation in TNBC. Knockdown of RIPK1 significantly suppressed the number of necroptotic cells and VM formation. Moreover, RIPK1 activated the p-AKT/eIF4E signaling pathway during necroptosis in TNBC. eIF4E was blocked by knockdown of RIPK1 or AKT inhibitors. Furthermore, we found that eIF4E promoted VM formation by promoting epithelial-mesenchymal transition (EMT) and the expression and activity of MMP2. In addition to its critical role in necroptosis-mediated VM, eIF4E was essential for VM formation. Knockdown of eIF4E significantly suppressed VM formation during necroptosis. Finally, through clinical significance, the results found that eIF4E expression in TNBC was positively correlated with the mesenchymal marker vimentin, the VM marker MMP2, and the necroptosis markers MLKL and AKT. In conclusion, RIPK1-dependent necroptosis promotes VM formation in TNBC. Necroptosis promotes VM formation by activating RIPK1/p-AKT/eIF4E signaling in TNBC. eIF4E promotes EMT and MMP2 expression and activity, leading to VM formation. Our study provides a rationale for necroptosis-mediated VM and also providing a potential therapeutic target for TNBC.

SIRT2 plays complex roles in neuroinflammation neuroimmunology-associated disorders

Neuroinflammation and neuroimmunology-associated disorders, including ischemic stroke and neurodegenerative disease, commonly cause severe neurologic function deficits, including bradypragia, hemiplegia, aphasia, and cognitive impairment, and the pathological mechanism is not completely clear. SIRT2, an NAD⁺-dependent deacetylase predominantly localized in the cytoplasm, was proven to play an important and paradoxical role in regulating ischemic stroke and neurodegenerative disease. This review summarizes the comprehensive mechanism of the crucial pathological functions of SIRT2 in apoptosis, necroptosis, autophagy, neuroinflammation, and immune response. Elaborating on the mechanism by which SIRT2 participates in neuroinflammation and neuroimmunology-associated disorders is beneficial to discover novel effective drugs for diseases, varying from vascular disorders to neurodegenerative diseases.

Development of a necroptosis-related gene signature and the immune landscape in ovarian cancer

BACKGROUND

Necroptosis is a novel type of programmed cell death distinct from apoptosis. However, the role of necroptosis in ovarian cancer (OC) remains unclear. The present study investigated the prognostic value of necroptosis-related genes (NRGs) and the immune landscape in OC.

METHODS

The gene expression profiling and clinical information were downloaded from the TCGA and GTEx databases. Differentially expressed NRGs (DE-NRGs) between OC and normal tissueswere identified. The regression analyses were conducted to screen the prognostic NRGs and construct the predictive risk model. Patients were then divided into high- and low-risk groups, and the GO and KEGG analyses were performed to explore bioinformatics functions between the two groups. Subsequently, the risk level and immune status correlations were assessed through the ESTIMATE and CIBERSORT algorithms. The tumor mutation burden (TMB) and the drug sensitivity were also analyzed based on the two-NRG signature in OC.

RESULTS

Totally 42 DE-NRGs were identified in OC. The regression analyses screened out two NRGs (MAPK10 and STAT4) with prognostic values for overall survival. The ROC curve showed a better predictive ability in five-year OS using the risk score. Immune-related functions were significantly enriched in the high- and low-risk group. Macrophages M1, T cells CD4 memory activated, T cells CD8, and T cells regulatory infiltration immune cells were associated with the low-risk score. The lower tumor microenvironment score was demonstrated in the high-risk group. Patients with lower TMB in the low-risk group showed a better prognosis, and a lower TIDE score suggested a better immune checkpoint inhibitor response in the high-risk group. Besides, cisplatin and paclitaxel were found to be more sensitive in the low-risk group.

CONCLUSIONS

MAPK10 and STAT4 can be important prognosis factors in OC, and the two-gene signature performs well in predicting survival outcomes. Our study provided novel ways of OC prognosis estimation and potential treatment strategy.

The roles of long non-coding RNAs in the necroptotic signaling of colon cancer cells

BACKGROUND

Necroptosis is a controlled form of necrosis which can be stimulated in cases where the apoptosis signal is absent. Necroptosis can be induced by DR family ligands and by various intracellular and extracellular stimuli that triggers the activation of DR family ligands. Necrostatins, which are specific RIP1 antagonists, prevent necroptosis by inhibiting RIP1 kinase, allowing survival and propagation of cells in the presence of DR ligands. Furthermore, there is a mounting evidence that long non-coding RNA (lncRNA) molecules accomplish vital functions in cell death processes such as apoptosis, autophagy, pyroptosis, and necroptosis. Accordingly, here we aimed to decipher the lncRNAs that are involved in the control and maintenance of necroptosis signaling.

METHODS AND RESULTS

Colon cancer cell lines, HT-29 and HCT-116 were used for the study. For the chemical modulation of necroptosis signaling, 5-Fluorouracil, TNF-α and/or Necrostatin-1 were used. Gene expression levels were determined by quantitative real-time PCR. Remarkably, lncRNA P50-associated COX-2 extragenic RNA (PACER) was identified to be suppressed in necroptosis-induced colon cancers, whereas the expression of PACER was restored when necroptosis was suppressed. In addition, no detectable change was observed in HCT-116 colon cancer cells, as these cells lack the expression of RIP3 kinase.

CONCLUSIONS

Collectively, current findings clearly imply that PACER have key regulatory roles in the control of necroptotic cell death signaling circuitry. Notably, the tumor promoter activity of PACER might be responsible for the lack of necroptotic death signal in cancer cells. Also, RIP3 kinase seems to be essential component in PACER-associated necroptosis.