Resistance to hypoxia-induced necroptosis is conferred by glycolytic pyruvate scavenging of mitochondrial superoxide in colorectal cancer cells. Cell Death Dis. 2013;4:e622. [PMID: 23640464 PMCID: PMC3674358 DOI: 10.1038/cddis.2013.149]

The function of necroptosis in liver cancer

Liver cancer is one of the most lethal cancers, and apoptosis resistance is a major obstacle contributing to chemotherapy failure in liver cancer treatment. Inducing cancer cell death by bypassing the apoptotic pathway is considered a promising approach to overcome this problem. Necroptosis is a non-caspase-dependent regulated mode of cell death mainly mediated by receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like (MLKL) protein, and the utilization of necroptosis for treating hepatocellular carcinoma (HCC) also offers a new hope for addressing liver cancer in the clinic. In this paper, the role of necroptosis in HCC as well as the effect on differentiation of liver cancer are reviewed. We also comparatively analyze the relationship among necroptosis, apoptosis, and necrosis, as well as summarize the characteristics and functions of key proteins involved in this pathway. The bidirectional regulation of necroptosis and the mitochondrial machinery within this pathway deserve attention.

Oxidative Stress and Redox Imbalance: Common Mechanisms in Cancer Stem Cells and Neurodegenerative Diseases

Oxidative stress (OS) is an established hallmark of cancer and neurodegenerative disorders (NDDs), which contributes to genomic instability and neuronal loss. This review explores the contrasting role of OS in cancer stem cells (CSCs) and NDDs. Elevated levels of reactive oxygen species (ROS) contribute to genomic instability and promote tumor initiation and progression in CSCs, while in NDDs such as Alzheimer's and Parkinson's disease, OS accelerates neuronal death and impairs cellular repair mechanisms. Both scenarios involve disruption of the delicate balance between pro-oxidant and antioxidant systems, which leads to chronic oxidative stress. Notably, CSCs and neurons display alterations in redox-sensitive signaling pathways, including Nrf2 and NF-κB, which influence cell survival, proliferation, and differentiation. Mitochondrial dynamics further illustrate these differences: enhanced function in CSCs supports adaptability and survival, whereas impairments in neurons heighten vulnerability. Understanding these common mechanisms of OS-induced redox imbalance may provide insights for developing interventions, addressing aging hallmarks, and potentially mitigating or preventing both cancer and NDDs.

Programmed cell death in nasopharyngeal carcinoma: Mechanisms and therapeutic targets

Programmed cell death is a type of autonomic and orderly cell death mode controlled by genes that maintain homeostasis and growth. Tumor is a typical manifestation of an imbalance in environmental homeostasis in the human body. Currently, several tumor treatments are designed to trigger the death of tumor cells. Nasopharyngeal carcinoma is one of the most common malignant tumors in China. It displays obvious regional and ethnic differences in its incidence, being typically high in the south and low in the north of China. Nasopharyngeal carcinoma is currently considered to be a polygenic inherited disease and is often mediated by the interaction between multiple genes or between genes and the environment. Apoptosis has long been considered the key to tumor treatment, while other cell death pathways have often been overlooked. The current study provides an overview of the relationship among apoptosis, autophagy, pyroptosis, necroptosis, ferroptosis, and nasopharyngeal carcinoma, and the regulatory pathways of nasopharyngeal carcinoma based on five cell death modes were synthesized from the view of molecule. We hope this review will help explore additional, novel programmed cell death targets for the treatment of nasopharyngeal carcinoma and thus promote in-depth research.

Proteomics and Metabolomics Study on the Responses of Sertoli Cells Infected With Brucella and Its bvfA-Deletion Strains

OBJECTIVE

To investigate the potential effects of BvfA in reproductive system damage caused by Brucella.

METHODS

Brucella intracellular multiplication ability was determined by a gentamicin protection assay; the LDH method was used to determine the lethal effect of Brucella on TM4 cells. Afterward, Label-free proteomics and LC-MS/MS metabolomics assays were combined to reveal differential abundant proteins and metabolites of TM4 cells infected with bvfA-deletion strains and parental strains. Finally, PRM mass spectrometry and western blot analysis were carried out to confirm differential expression of proteins.

RESULTS

This report demonstrated that bvfA-deletion strains failed to invade TM4 cells and reconstitution of invasion when a strain with gene bvfA was reintroduced to the deletion strain in 3 h. The bvfA-deletion exhibited weakened intracellular multiplication compared with parental strains in TM4 cells in 12 h; however, the death rate of TM4 cells infected with bvfA-deletion strains was higher than that of TM4 cells infected with parental strains. Combined proteomics and metabolomics analyses revealed that the differential abundant proteins and metabolites in TM4 cells infected with bvfA-deletion and parental strains mainly involved the mineral absorption-related pathway, NADH:ubiquinone oxidoreductase subunit-related mitochondrial respiratory signaling pathway, and sphingolipid signaling pathway of TM4 cells. These three signaling pathways were involved in expression changes of TRPM6/7, STEAP1, Gnaq, Trp53, Pbk, Tns2, Akt2, and the NADH:ubiquinone oxidoreductase subunit, as well as content changes of l-Valine, l-Isoleucine, l-Methionine, PC, PE DG, and SM metabolites.

SIGNIFICANCE

These results indicated that BvfA of Brucella abortus S19 affected the above proteins and metabolites in TM4 cells.

Role of glucose metabolic reprogramming in colorectal cancer progression and drug resistance

Colorectal cancer (CRC), with the incidence and mortality rising on a yearly basis, greatly threatens people's health. It is considered an important hallmark of tumorigenesis that aberrant glucose metabolism in cancer cells, particularly the Warburg effect. In CRC, the Warburg effect predominantly influences cancer development and progression via its involvement in the glycolytic pathway regarding cell metabolism. The critical mechanisms underlying this process include key glycolytic enzymes, transport proteins, regulatory molecules, and signaling pathways. Furthermore, targeting the reprogrammed glucose metabolism in cancer cells can be potentially used for CRC treatment. However, the mechanisms driving CRC onset and progression, especially in relation to glucose metabolism reprogramming, are not fully understood and represent an emerging field of research. The review aims at providing new insights into the role that glucose metabolism reprogramming plays in the progression of CRC progression together with its resistance to treatment. Ultimately, these insights strive to diminish the risks of CRC metastasis and recurrence.

Gentiopicroside-Induced gastric cancer necroptosis via the HIF-1 signaling pathway: A study involving molecular docking and experimental validation

OBJECTIVES

Gentiopicroside is an effective treatment for several types of cancer, inducing numerous forms of programmed cancer cell death. However, there are few investigations into the role of necroptosis. By utilizing molecular docking, and experimental validation, this study aims to investigate whether gentiopicroside elicits necroptosis in gastric cancer.

METHODS

Using software PyMOL and AutoDock, gentiopicroside was docked with RIPK1, RIPK3, MLKL and HIF-1α proteins. And a cell study was performed based on SGC7901 cells. The necroptosis-related proteins and HIF-1 signaling pathways were explored using western blot (WB) analysis. Finally, an animal study was performed to test the inhibitory effect in vivo.

RESULTS

Docking studies indicated that the docking energies of gentiopicroside to necroptosis-related proteins and necroptosis-characteristic proteins are all below -5 kcal/mol. Additionally, gentiopicroside cells reduce gastric cancer viability and inhibit proliferation. Results from the animal experiments indicated that gentiopicroside inhibits the growth of the gastric cancer xenograft tumor. Western blot and immunohistochemistry (IHC) staining demonstrated that gentiopicroside higher p-receptor-interacting protein kinase 3(p-RIPK3) levels in vitro and in vivo.

CONCLUSION

The findings of this study revealed that necroptosis is involved in the inhibitory effect of gentiopicroside toward gastric cancer.

Fructose shields human colorectal cancer cells from hypoxia-induced necroptosis

Recent studies have shown that high dietary fructose intake enhances intestinal tumor growth in mice. Our previous work indicated that glucose enables hypoxic colorectal cancer (CRC) cells to resist receptor-interacting protein (RIP)-dependent necroptosis. Despite having the same chemical formula, glucose and fructose are absorbed through different transporters yet both can enter the glycolytic metabolic pathway. The excessive intake of dietary fructose, leading to its overflow into the colon, allows colonic cells to absorb fructose apically. This study explores the mechanisms behind apical fructose-mediated death resistance in CRC cells under hypoxic stress. Utilizing three CRC cell lines (Caco-2, HT29, and T84) under normoxic and hypoxic conditions with varying fructose concentrations, we assessed lactate dehydrogenase (LDH) activity, RIP1/3 complex formation (a necroptosis marker), and cell integrity. We investigated the role of fructose in glycolytic-mediated death resistance using glycolytic inhibitors iodoacetate (IA, a glycolytic inhibitor to glyceraldehyde 3-phosphate dehydrogenase), and UK5099 (UK, an inhibitor to mitochondrial pyruvate carrier). Our findings reveal that apical fructose prevents the hypoxia-induced RIP-dependent necroptosis in Caco-2 and HT29 cells. Fructose exposure under hypoxia also preserved epithelial integrity. IA, but not UK, blocked fructose-mediated glycolytic metabolite production and necrosis, indicating that anaerobic glycolytic metabolites facilitate death resistance. Notably, fructose treatment upregulated pyruvate kinase (PK)-M1 mRNA in hypoxic Caco-2 and HT29 cells, while PKM2 upregulation was exclusive to HT29 cells. In conclusion, apical fructose utilization through glycolysis effectively inhibits hypoxia-induced RIP-dependent necroptosis in CRC cells, shedding light on potential metabolic adaptation mechanisms in the tumor microenvironment and suggesting novel targets for therapeutic intervention.

Challenges of Regulated Cell Death: Implications for Therapy Resistance in Cancer

Regulated cell death, a regulatory form of cell demise, has been extensively studied in multicellular organisms. It plays a pivotal role in maintaining organismal homeostasis under normal and pathological conditions. Although alterations in various regulated cell death modes are hallmark features of tumorigenesis, they can have divergent effects on cancer cells. Consequently, there is a growing interest in targeting these mechanisms using small-molecule compounds for therapeutic purposes, with substantial progress observed across various human cancers. This review focuses on summarizing key signaling pathways associated with apoptotic and autophagy-dependent cell death. Additionally, it explores crucial pathways related to other regulated cell death modes in the context of cancer. The discussion delves into the current understanding of these processes and their implications in cancer treatment, aiming to illuminate novel strategies to combat therapy resistance and enhance overall cancer therapy.

Hypoxia-mediated programmed cell death is involved in the formation of wooden breast in broilers

BACKGROUND

Wooden breast (WB) myopathy is a common myopathy found in commercial broiler chickens worldwide. Histological examination has revealed that WB myopathy is accompanied by damage to the pectoralis major (PM) muscle. However, the underlying mechanisms responsible for the formation of WB in broilers have not been fully elucidated. This study aimed to investigate the potential role of hypoxia-mediated programmed cell death (PCD) in the formation of WB myopathy.

RESULTS

Histological examination and biochemical analysis were performed on the PM muscle of the control (CON) and WB groups. A significantly increased thickness of the breast muscle in the top, middle, and bottom portions (P<0.01) was found along with pathological structure damage of myofibers in the WB group. The number of capillaries per fiber in PM muscle, and the levels of pO2 and sO2 in the blood, were significantly decreased (P < 0.01), while the levels of pCO2 and TCO2 in the blood were significantly increased (P < 0.05), suggesting hypoxic conditions in the PM muscle of the WB group. We further evaluated the PCD-related pathways including autophagy, apoptosis, and necroptosis to understand the consequence response to enhanced hypoxic conditions in the PM muscle of birds with WB. The ratio of LC3 II to LC3 I, and the autophagy-related factors HIF-1α, BNIP3, Beclin1, AMPKα, and ULK1 at the mRNA and protein levels, were all significantly upregulated (P < 0.05), showing that autophagy occurred in the PM muscle of the WB group. The apoptotic index, as well as the expressions of Bax, Cytc, caspase 9, and caspase 3, were significantly increased (P < 0.05), whereas Bcl-2 was significantly decreased (P < 0.05) in the WB-affected PM muscle, indicating the occurrence of apoptosis mediated by the mitochondrial pathway. Additionally, the expressions of necroptosis-related factors RIP1, RIP3, and MLKL, as well as NF-κB and the pro-inflammatory cytokines TNF-α, IL-1β, and IL-6, were all significantly enhanced (P < 0.05) in the WB-affected PM muscle.

CONCLUSIONS

The WB myopathy reduces blood supply and induces hypoxia in the PM muscle, which is closely related to the occurrence of PCD including apoptosis, autophagy, and necroptosis within myofibers, and finally leads to abnormal muscle damage and the development of WB in broilers.

Non-apoptotic regulated cell death mediates reprogramming of the tumour immune microenvironment by macrophages

Tumour immune microenvironment (TIME) plays an indispensable role in tumour progression, and tumour-associated macrophages (TAMs) are the most abundant immune cells in TIME. Non-apoptotic regulated cell death (RCD) can avoid the influence of tumour apoptosis resistance on anti-tumour immune response. Specifically, autophagy, ferroptosis, pyroptosis and necroptosis mediate the crosstalk between TAMs and tumour cells in TIME, thus reprogram TIME and affect the progress of tumour. In addition, although some achievements have been made in immune checkpoint inhibitors (ICIs), there is still defect that ICIs are only effective for some people because non-apoptotic RCD can bypass the apoptosis resistance of tumour. As a result, ICIs combined with targeting non-apoptotic RCD may be a promising solution. In this paper, the basic molecular mechanism of non-apoptotic RCD, the way in which non-apoptotic RCD mediates crosstalk between TAMs and tumour cells to reprogram TIME, and the latest research progress in targeting non-apoptotic RCD and ICIs are reviewed.

Creation of signatures and identification of molecular subtypes based on disulfidptosis-related genes for glioblastoma patients' prognosis and immunological activity

BACKGROUND

In recent times, disulfidptosis, an intricate form of cellular demise, has garnered attention due to its impact on prognosis, tumor progression and treatment response. Nevertheless, the exact significance of disulfidptosis-related genes (DisRGs) in glioblastoma (GBM) remains enigmatic.

METHODS

The GEO and TCGA databases provided transcriptional and clinically relevant data on tumor samples, while the GTEx database provided data on healthy tissues. Disulfidptosis-related genes (DisRGs) were procured from previous scholarly investigations. The expression profile of DisRGs was initially scrutinized among patients diagnosed with GBM, subsequent to which their prognostic value was explored. Through consensus clustering, we constructed DisRGs-related clusters and gene subtypes. Our results established that the DisRG-related clusters had differentially expressed genes, resulting in a DisulfidptosisScore model, which had a positive prognostic value.

RESULTS

The differential expression profile of 24 DisRGs between GBM samples and healthy samples was acquired. Through consensus cluster analysis, two distinct disulfidptosis subtypes, namely DisRGcluster A and DisRGcluster B, were identified. Then, the DisulfidptosisScore model including 4 characteristic genes was constructed.Notably, patients with GBM assigned with lower score demonstrated a considerably longer overall survival (OS) compared to those with higher score.

CONCLUSION

We have effectively devised a prognostic model associated with disulfidptosis, presenting autonomous prognostic predictions for patients with GBM. These findings serve as a valuable addition to the current comprehension of disulfidptosis and offer fresh theoretical substantiation for the development of enhanced treatment strategies.

Targeting the Warburg effect: A revisited perspective from molecular mechanisms to traditional and innovative therapeutic strategies in cancer

Cancer reprogramming is an important facilitator of cancer development and survival, with tumor cells exhibiting a preference for aerobic glycolysis beyond oxidative phosphorylation, even under sufficient oxygen supply condition. This metabolic alteration, known as the Warburg effect, serves as a significant indicator of malignant tumor transformation. The Warburg effect primarily impacts cancer occurrence by influencing the aerobic glycolysis pathway in cancer cells. Key enzymes involved in this process include glucose transporters (GLUTs), HKs, PFKs, LDHs, and PKM2. Moreover, the expression of transcriptional regulatory factors and proteins, such as FOXM1, p53, NF-κB, HIF1α, and c-Myc, can also influence cancer progression. Furthermore, lncRNAs, miRNAs, and circular RNAs play a vital role in directly regulating the Warburg effect. Additionally, gene mutations, tumor microenvironment remodeling, and immune system interactions are closely associated with the Warburg effect. Notably, the development of drugs targeting the Warburg effect has exhibited promising potential in tumor treatment. This comprehensive review presents novel directions and approaches for the early diagnosis and treatment of cancer patients by conducting in-depth research and summarizing the bright prospects of targeting the Warburg effect in cancer.

Triggering endogenous Z-RNA sensing for anti-tumor therapy through ZBP1-dependent necroptosis

ZBP1 senses viral Z-RNAs to induce necroptotic cell death to restrain viral infection. ZBP1 is also thought to recognize host cell-derived Z-RNAs to regulate organ development and tissue inflammation in mice. However, it remains unknown how the host-derived Z-RNAs are formed and how these endogenous Z-RNAs are sensed by ZBP1. Here, we report that oxidative stress strongly induces host cell endogenous Z-RNAs, and the Z-RNAs then localize to stress granules for direct sensing by ZBP1 to trigger necroptosis. Oxidative stress triggers dramatically increase Z-RNA levels in tumor cells, and the Z-RNAs then directly trigger tumor cell necroptosis through ZBP1. Localization of the induced Z-RNAs to stress granules is essential for ZBP1 sensing. Oxidative stress-induced Z-RNAs significantly promote tumor chemotherapy via ZBP1-driven necroptosis. Thus, our study identifies oxidative stress as a critical trigger for Z-RNA formation and demonstrates how Z-RNAs are directly sensed by ZBP1 to trigger anti-tumor necroptotic cell death.

Recent advances in natural compounds inducing non-apoptotic cell death for anticancer drug resistance

The induction of cell death is recognized as a potent strategy for cancer treatment. Apoptosis is an extensively studied form of cell death, and multiple anticancer drugs exert their therapeutic effects by inducing it. Nonetheless, apoptosis evasion is a hallmark of cancer, rendering cancer cells resistant to chemotherapy drugs. Consequently, there is a growing interest in exploring novel non-apoptotic forms of cell death, such as ferroptosis, necroptosis, pyroptosis, and paraptosis. Natural compounds with anticancer properties have garnered significant attention due to their advantages, including a reduced risk of drug resistance. Over the past two decades, numerous natural compounds have been discovered to exert anticancer and anti-resistance effects by triggering these four non-apoptotic cell death mechanisms. This review primarily focuses on these four non-apoptotic cell death mechanisms and their recent advancements in overcoming drug resistance in cancer treatment. Meanwhile, it highlights the role of natural compounds in effectively addressing cancer drug resistance through the induction of these forms of non-apoptotic cell death.

Role of glycolysis in inflammatory bowel disease and its associated colorectal cancer

Inflammatory bowel disease (IBD) has been referred to as the "green cancer," and its progression to colorectal cancer (CRC) poses a significant challenge for the medical community. A common factor in their development is glycolysis, a crucial metabolic mechanism of living organisms, which is also involved in other diseases. In IBD, glycolysis affects gastrointestinal components such as the intestinal microbiota, mucosal barrier function, and the immune system, including macrophages, dendritic cells, T cells, and neutrophils, while in CRC, it is linked to various pathways, such as phosphatidylinositol-3-kinase (PI3K)/AKT, AMP-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), and transcription factors such as p53, Hypoxia-inducible factor (HIF), and c-Myc. Thus, a comprehensive study of glycolysis is essential for a better understanding of the pathogenesis and therapeutic targets of both IBD and CRC. This paper reviews the role of glycolysis in diseases, particularly IBD and CRC, via its effects on the intestinal microbiota, immunity, barrier integrity, signaling pathways, transcription factors and some therapeutic strategies targeting glycolytic enzymes.

A necroptosis-related gene signature to predict prognosis and immune features in hepatocellular carcinoma

BACKGROUND AND AIM

Necroptosis plays an important role in hepatocellular carcinoma (HCC) development, recurrence, and immunotherapy tolerance. We aimed to build a new prognostic necroptosis-related gene signature that could be used for survival and immunotherapy prediction in HCC patients.

METHODS

We found that necroptosis was associated with HCC progression and survival outcomes and was involved in the immune infiltration of HCC. Multiple bioinformatics methods including WGCNA, LASSO-Cox regression, stepwise Cox regression, and Random Forest and Boruta model analysis, were used to establish a prognostic profile related to necroptosis. The necroptosis-related gene signature was validated in ICGC and GSE14520 datasets.

RESULTS

This five-gene signature showed excellent predictive performance and was an independent risk factor for patients' overall survival outcome in the three cohorts. Moreover, this signature was an exact predictor using fewer genes than previous gene signatures. Finally, qRT-PCR and immunohistochemical staining investigations were performed in previously collected fresh frozen tumor tissues from HCC patients and their paracancerous normal tissues, and the results were consistent with the bioinformatics results. We found that LGALS3 not only affected the proliferation and migration ability of HepG2 cells but also affected necroptosis and the expression of inflammatory cytokines.

CONCLUSION

In summary, we established and validated an individualized prognostic profile related to necroptosis to forecast the therapeutic response to immune therapy, which might offer a potential non-apoptotic therapeutic target for HCC patients.

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.

Ferroptosis and tumor immunotherapy: A promising combination therapy for tumors

Low response rate and treatment resistance are frequent problems in the immunotherapy of tumors, resulting in the unsatisfactory therapeutic effects. Ferroptosis is a form of cell death characterized by the accumulation of lipid peroxides. In recent years, it has been found that ferroptosis may be related to the treatment of cancer. Various immune cells (including macrophages and CD8⁺ T cells) can induce ferroptosis of tumor cells, and synergistically enhance the anti-tumor immune effects. However, the mechanisms are different for each cell types. DAMP released in vitro by cancer cells undergoing ferroptosis lead to the maturation of dendritic cells, cross-induction of CD8⁺ T cells, IFN-γ production and M1 macrophage production. Thus, it activates the adaptability of the tumor microenvironment and forms positive feedback of the immune response. It suggests that induction of ferroptosis may contribute to reducing resistance of cancer immunotherapy and has great potential in cancer therapy. Further research into the link between ferroptosis and tumor immunotherapy may offer hope for those cancers that are difficult to treat. In this review, we focus on the role of ferroptosis in tumor immunotherapy, explore the role of ferroptosis in various immune cells, and discuss potential applications of ferroptosis in tumor immunotherapy.

Glutamine induces remodeling of tight junctions in Caco-2 colorectal cancer cell

Malignant cells often exhibit significant metabolic alterations, including the utilization of different nutrients to meet energetic and biosynthetic demands. Recent studies have shown that glutamine can support primary colorectal tumor growth and also serve as an alternate energy source during distant metastasis under glucose-limited conditions. However, the overall effects of glutamine on cancer cell physiology are not completely understood. In this study, we investigated how glutamine impacts epithelial integrity in colorectal cancer cells under glucose deprivation. Human colorectal cancer (Caco-2) cells were grown to confluency in transwells and cultured in glucose/pyruvate-free DMEM with various glutamine concentrations (0-50 mM). Cell viability was assessed, and monolayer integrity was examined in terms of transepithelial resistance (TER) and paracellular permeability. Tight junction (TJ) component proteins were examined by immunofluorescence staining and Western blotting. A dose-dependent decrease in TER was observed in Caco-2 cells, but paracellular permeability was not affected after 24 h incubation with glutamine. At the same time, the TJ proteins, zonula occludens (ZO)-1 and Claudin-1, showed lateral undulations and punctate staining patterns accompanied by enlargement of cellular and nuclear sizes. Furthermore, decreased protein levels of ZO-1, but not claudin-1, were found in detergent-insoluble cellular fractions. Notably, the decreased TER and alterations in TJ structure were not associated with cell viability changes. Moreover, the addition of glutamate, which is produced by the first step of glutamine catabolism, had no impact on TER. Our results suggested that the enteral glutamine may play an important role in the regulation of TJ dynamics in colorectal cancer cells.

Global publication trends and research trends of necroptosis application in tumor: A bibliometric analysis

Introduction: Necroptosis is an alternative, caspase-independent programmed cell death that appears when apoptosis is inhibited. A gowing number of studies have reflected the link between necroptosis and tumors. However, only some systematical bibliometric analyses were focused on this field. In this study, we aimed to identify and visualize the cooperation between countries, institutions, authors, and journals through a bibliometric analysis to help understand the hotspot trends and emerging topics regarding necroptosis and cancer research. Methods: The articles and reviews on necroptosis and cancer were obtained from the Web of Science Core Collection on 16 September 2022. Countries, institutions, authors, references, and keywords in this field were visually analyzed by CtieSpace 5.8.R3, VOSviewer 1.6.18, and R package "bibliometrix." Results: From 2006 to 2022, 2,216 qualified original articles and reviews on necroptosis in tumors were published in 685 academic journals by 13,009 authors in 789 institutions from 75 countries/regions. Publications focusing on necroptosis and cancer have increased violently in the past 16 years, while the citation number peaked around 2008-2011. Most publications were from China, while the United States maintained the dominant position as a "knowledge bridge" in necroptosis and cancer research; meanwhile, Ghent University and the Chinese Academy of Sciences were the most productive institutions. Moreover, only a tiny portion of the articles were multiple-country publications. Peter Vandenabeele had the most significant publications, while Alexei Degterev was most often co-cited. Peter Vandenabeele also gets the highest h-index and g-index in this research field. Cell Death and Disease was the journal with the most publications on necroptosis and cancer, which was confirmed to be the top core source by Bradford's Law. At the same time, Cell was the leading co-cited journal, and the focus area of these papers was molecular, biology, and immunology. High-frequency keywords mainly contained those that are molecularly related (MLKL, NF-kB, TNF, RIPK3, RIPK1), pathological process related (necroptosis, apoptosis, cell-death, necrosis, autophagy), and mechanism related (activation, expression, mechanisms, and inhibition). Conclusion: This study comprehensively overviews necroptosis and cancer research using bibliometric and visual methods. Research related to necroptosis and cancer is flourishing. Cooperation and communication between countries and institutions must be further strengthened. The information in our paper would provide valuable references for scholars focusing on necroptosis and cancer.

Necroptosis: A Pathogenic Negotiator in Human Diseases

Over the past few decades, mechanisms of programmed cell death have attracted the scientific community because they are involved in diverse human diseases. Initially, apoptosis was considered as a crucial mechanistic pathway for programmed cell death; recently, an alternative regulated mode of cell death was identified, mimicking the features of both apoptosis and necrosis. Several lines of evidence have revealed that dysregulation of necroptosis leads to pathological diseases such as cancer, cardiovascular, lung, renal, hepatic, neurodegenerative, and inflammatory diseases. Regulated forms of necrosis are executed by death receptor ligands through the activation of receptor-interacting protein kinase (RIPK)-1/3 and mixed-lineage kinase domain-like (MLKL), resulting in the formation of a necrosome complex. Many papers based on genetic and pharmacological studies have shown that RIPKs and MLKL are the key regulatory effectors during the progression of multiple pathological diseases. This review focused on illuminating the mechanisms underlying necroptosis, the functions of necroptosis-associated proteins, and their influences on disease progression. We also discuss numerous natural and chemical compounds and novel targeted therapies that elicit beneficial roles of necroptotic cell death in malignant cells to bypass apoptosis and drug resistance and to provide suggestions for further research in this field.

Necroptosis-related lncRNAs: Combination of bulk and single-cell sequencing reveals immune landscape alteration and a novel prognosis stratification approach in lung adenocarcinoma

Necroptosis, which is recently recognized as a form of programmed cell death, plays a critical role in cancer biology, including tumorigenesis and cancer immunology. It was recognized not only to defend against tumor progression by suppressing adaptive immune responses but also to promote tumorigenesis and cancer metastasis after recruiting inflammatory responses. Thus the crucial role of necrosis in tumorigenesis has attracted increasing attention. Due to the heterogeneity of the tumor immune microenvironment (TIME) in lung adenocarcinoma (LUAD), the prognosis and the response to immunotherapy vary distinctly across patients, underscoring the need for a stratification algorithm for clinical practice. Although previous studies have formulated the crucial role of lncRNAs in tumorigenicity, the relationship between necroptosis-related lncRNAs, TIME, and the prognosis of patients with LUAD was still elusive. In the current study, a robust and novel prognostic stratification model based on Necroptosis-related LncRNA Risk Scoring (NecroLRS) and clinicopathological parameters was constructed and systemically validated in both internal and external validation cohorts. The expression profile of four key lncRNAs was further validated by qRT-PCR in 4 human LUAD cell lines. And a novel immune landscape alteration was observed between NecroLRS-High and -Low patients. To further elucidate the mechanism of necroptosis in the prognosis of LUAD from a single-cell perspective, a novel stratification algorithm based on K-means clustering was introduced to extract both malignant and NecroLRS-High subsets from epithelial cells. And the necroptosis-related immune infiltration landscape and developmental trajectory were investigated respectively. Critically, NecroLRS was found to be positively correlated with neutrophil enrichment, inflammatory immune response, and malignant phenotypes of LUAD. In addition, novel ligand-receptor pairs between NecroLRS-High cells and other immunocytes were investigated and optimal therapeutic compounds were screened to provide potential targets for future studies. Taken together, our findings reveal emerging mechanisms of necroptosis-induced immune microenvironment alteration on the deteriorative prognosis and may contribute to improved prognosis and individualized precision therapy for patients with LUAD.

Crosstalk between regulated necrosis and micronutrition, bridged by reactive oxygen species

The discovery of regulated necrosis revitalizes the understanding of necrosis from a passive and accidental cell death to a highly coordinated and genetically regulated cell death routine. Since the emergence of RIPK1 (receptor-interacting protein kinase 1)-RIPK3-MLKL (mixed lineage kinase domain-like) axis-mediated necroptosis, various other forms of regulated necrosis, including ferroptosis and pyroptosis, have been described, which enrich the understanding of pathophysiological nature of diseases and provide novel therapeutics. Micronutrients, vitamins, and minerals, position centrally in metabolism, which are required to maintain cellular homeostasis and functions. A steady supply of micronutrients benefits health, whereas either deficiency or excessive amounts of micronutrients are considered harmful and clinically associated with certain diseases, such as cardiovascular disease and neurodegenerative disease. Recent advance reveals that micronutrients are actively involved in the signaling pathways of regulated necrosis. For example, iron-mediated oxidative stress leads to lipid peroxidation, which triggers ferroptotic cell death in cancer cells. In this review, we illustrate the crosstalk between micronutrients and regulated necrosis, and unravel the important roles of micronutrients in the process of regulated necrosis. Meanwhile, we analyze the perspective mechanism of each micronutrient in regulated necrosis, with a particular focus on reactive oxygen species (ROS).

Prognosis analysis of necroptosis-related genes in colorectal cancer based on bioinformatic analysis

Background: Colorectal cancer (CRC) is one gastrointestinal malignancy, accounting for 10% of cancer diagnoses and cancer-related deaths worldwide each year. Therefore, it is urgent to identify genes involved in CRC predicting the prognosis.

Methods: CRC’s data were acquired from the Gene Expression Omnibus (GEO) database (GSE39582 and GSE41258 datasets) and The Cancer Genome Atlas (TCGA) database. The differentially expressed necroptosis-related genes (DENRGs) were sorted out between tumor and normal tissues. Univariate Cox regression analysis and least absolute shrinkage and selectionator operator (LASSO) analysis were applied to selected DENRGs concerning patients’ overall survival and to construct a prognostic biomarker. The effectiveness of this biomarker was assessed by the Kaplan–Meier curve and the receiver operating characteristic (ROC) analysis. The GSE39582 dataset was utilized as external validation for the prognostic signature. Moreover, using univariate and multivariate Cox regression analyses, independent prognostic factors were identified to construct a prognostic nomogram. Next, signaling pathways regulated by the signature were explored through the gene set enrichment analysis (GSEA). The single sample gene set enrichment analysis (ssGSEA) algorithm and tumor immune dysfunction and exclusion (TIDE) were used to explore immune correlation in the two groups, high-risk and low-risk ones. Finally, prognostic genes’ expression was examined in the GSE41258 dataset.

Results: In total, 27 DENRGs were filtered, and a necroptosis-related prognostic signature based on 6 DENRGs was constructed, which may better understand the overall survival (OS) of CRC. The Kaplan–Meier curve manifested the effectiveness of the prognostic signature, and the ROC curve showed the same result. In addition, univariate and multivariate Cox regression analyses revealed that age, pathology T, and risk score were independent prognostic factors, and a nomogram was established. Furthermore, the prognostic signature was most significantly associated with the apoptosis pathway. Meanwhile, 24 immune cells represented significant differences between two groups, like the activated B cell. Furthermore, 32 immune checkpoints, TIDE scores, PD-L1 scores, and T-cell exclusion scores were significantly different between the two groups. Finally, a 6-gene prognostic signature represented different expression levels between tumor and normal samples significantly in the GSE41258 dataset.

Conclusion: Our study established a signature including 6 genes and a prognostic nomogram that could significantly assess the prognosis of patients with CRC.

Construction of a Novel Prognostic Signature in Lung Adenocarcinoma Based on Necroptosis-Related lncRNAs

Background: Long non-coding RNAs (lncRNAs) are drawing increasing attention as promising predictors of prognosis for lung adenocarcinoma (LUAD) patients. Necroptosis, a novel regulated mechanism of necrotic cell death, plays an important role in the biological process of cancer. The aim of this study was to identify the necroptosis-related lncRNAs (NRLRs) in a LUAD cohort and establish a necroptosis-related lncRNA signature (NRLSig) to stratify LUAD patients.

Methods: NRLRs were identified in LUAD patients from The Cancer Genome Atlas (TCGA) database using Pearson correlation analysis between necroptosis-related genes and lncRNAs. Then the NRLSig was identified using univariate Cox regression analysis and LASSO regression analysis. Assessments of the signature were performed based on survival analysis, receiver operating characteristic (ROC) curve analysis and clustering analysis. Next, a nomogram containing the NRLSig and clinical information was developed through univariate and multivariate Cox regression analysis. Further, functional enrichment analysis of the selected lncRNAs in NRLSig and the association between NRLSig and the immune infiltration were also evaluated.

Results: A 4-lncRNA signature, incorporating LINC00941, AP001453.2, AC026368.1, and AC236972.3, was identified to predict overall survival (OS) and stratify LUAD patients into different groups. Survival analysis, ROC curve analysis and clustering analysis showed good performance in the prognostic prediction of the lncRNA signature. Then, a nomogram containing the NRLSig was developed and showed satisfactory predictive accuracy, calibration and clinical usefulness. The co-expressed genes of selected NRLRs were enriched in several biological functions and signaling pathways. Finally, differences in the abundance of immune cells were investigated among the high-risk group and low-risk group divided by the NRLSig.

Conclusion: The proposed NRLSig may provide promising therapeutic targets or prognostic predictors for LUAD patients.

Metabolic tricks of cancer cells

One of the characteristics of cancer cells important for tumorigenesis is their metabolic plasticity. Indeed, in various stress conditions, cancer cells can reshape their metabolic pathways to support the increased energy request due to continuous growth and rapid proliferation. Moreover, selective pressures in the tumor microenvironment, such as hypoxia, acidosis, and competition for resources, force cancer cells to adapt by complete reorganization of their metabolism. In this review, we highlight the characteristics of cancer metabolism and discuss its clinical significance, since overcoming metabolic plasticity of cancer cells is a key objective of modern cancer therapeutics and a better understanding of metabolic reprogramming may lead to the identification of possible targets for cancer therapy.

TDP-43 Proteinopathy Causes Broad Metabolic Alterations including TCA Cycle Intermediates and Dopamine Levels in Drosophila Models of ALS

ALS is a fatal, complex neurodegenerative disorder that causes selective degeneration of motor neurons. ALS patients exhibit symptoms consistent with altered cellular energetics such as hypermetabolism, weight loss, dyslipidemia, insulin resistance, and altered glucose tolerance. Although evidence supports metabolic changes in ALS patients, metabolic alterations at a cellular level remain poorly understood. Here, we used a Drosophila model of ALS based on TDP-43 expression in motor neurons that recapitulates hallmark features of motor neuron disease including TDP-43 aggregation, locomotor dysfunction, and reduced lifespan. To gain insights into metabolic changes caused by TDP-43, we performed global metabolomic profiling in larvae expressing TDP-43 (WT or ALS associated mutant variant, G298S) and identified significant alterations in several metabolic pathways. Here, we report alterations in multiple metabolic pathways and highlight upregulation of TCA cycle metabolites and defects in neurotransmitter levels. We also show that modulating TCA cycle flux either genetically or by dietary intervention mitigates TDP-43-dependent locomotor defects. In addition, dopamine levels are significantly reduced in the context of TDP-43G298S, and we find that treatment with pramipexole, a dopamine agonist, improves locomotor function in vivo in Drosophila models of TDP-43 proteinopathy.

Targeting the Interplay between Cancer Metabolic Reprogramming and Cell Death Pathways as a Viable Therapeutic Path

In cancer cells, metabolic adaptations are often observed in terms of nutrient absorption, biosynthesis of macromolecules, and production of energy necessary to meet the needs of the tumor cell such as uncontrolled proliferation, dissemination, and acquisition of resistance to death processes induced by both unfavorable environmental conditions and therapeutic drugs. Many oncogenes and tumor suppressor genes have a significant effect on cellular metabolism, as there is a close relationship between the pathways activated by these genes and the various metabolic options. The metabolic adaptations observed in cancer cells not only promote their proliferation and invasion, but also their survival by inducing intrinsic and acquired resistance to various anticancer agents and to various forms of cell death, such as apoptosis, necroptosis, autophagy, and ferroptosis. In this review we analyze the main metabolic differences between cancer and non-cancer cells and how these can affect the various cell death pathways, effectively determining the susceptibility of cancer cells to therapy-induced death. Targeting the metabolic peculiarities of cancer could represent in the near future an innovative therapeutic strategy for the treatment of those tumors whose metabolic characteristics are known.

RIPK3 signaling and its role in the pathogenesis of cancers

RIPK3 (receptor-interacting protein kinase 3) is a serine/threonine-protein kinase. As a key component of necrosomes, RIPK3 is an essential mediator of inflammatory factors (such as TNFα-tumor necrosis factor α) and infection-induced necroptosis, a programmed necrosis. In addition, RIPK3 signaling is also involved in the regulation of apoptosis, cytokine/chemokine production, mitochondrial metabolism, autophagy, and cell proliferation by interacting with and/or phosphorylating the critical regulators of the corresponding signaling pathways. Similar to apoptosis, RIPK3-signaling-mediated necroptosis is inactivated in most types of cancers, suggesting RIPK3 might play a critical suppressive role in the pathogenesis of cancers. However, in some inflammatory types of cancers, such as pancreatic cancers and colorectal cancers, RIPK3 signaling might promote cancer development by stimulating proliferation signaling in tumor cells and inducing an immunosuppressive response in the tumor environment. In this review, we summarize recent research progress in the regulators of RIPK3 signaling, and discuss the function of this pathway in the regulation of mixed lineage kinase domain-like (MLKL)-mediated necroptosis and MLKL-independent cellular behaviors. In addition, we deliberate the potential roles of RIPK3 signaling in the pathogenesis of different types of cancers and discuss the potential strategies for targeting this pathway in cancer therapy.

Targeting Drug Chemo-Resistance in Cancer Using Natural Products

Cancer is one of the leading causes of death globally. The development of drug resistance is the main contributor to cancer-related mortality. Cancer cells exploit multiple mechanisms to reduce the therapeutic effects of anticancer drugs, thereby causing chemotherapy failure. Natural products are accessible, inexpensive, and less toxic sources of chemotherapeutic agents. Additionally, they have multiple mechanisms of action to inhibit various targets involved in the development of drug resistance. In this review, we have summarized the basic research and clinical applications of natural products as possible inhibitors for drug resistance in cancer. The molecular targets and the mechanisms of action of each natural product are also explained. Diverse drug resistance biomarkers were sensitive to natural products. P-glycoprotein and breast cancer resistance protein can be targeted by a large number of natural products. On the other hand, protein kinase C and topoisomerases were less sensitive to most of the studied natural products. The studies discussed in this review will provide a solid ground for scientists to explore the possible use of natural products in combination anticancer therapies to overcome drug resistance by targeting multiple drug resistance mechanisms.

Vaccination with early ferroptotic cancer cells induces efficient antitumor immunity

Background

Immunotherapy represents the future of clinical cancer treatment. The type of cancer cell death determines the antitumor immune response and thereby contributes to the efficacy of anticancer therapy and long-term survival of patients. Induction of immunogenic apoptosis or necroptosis in cancer cells does activate antitumor immunity, but resistance to these cell death modalities is common. Therefore, it is of great importance to find other ways to kill tumor cells. Recently, ferroptosis has been identified as a novel, iron-dependent form of regulated cell death but whether ferroptotic cancer cells are immunogenic is unknown.

Methods

Ferroptotic cell death in murine fibrosarcoma MCA205 or glioma GL261 cells was induced by RAS-selective lethal 3 and ferroptosis was analyzed by flow cytometry, atomic force and confocal microscopy. ATP and high-mobility group box 1 (HMGB1) release were detected by luminescence and ELISA assays, respectively. Immunogenicity in vitro was analyzed by coculturing of ferroptotic cancer cells with bone-marrow derived dendritic cells (BMDCs) and rate of phagocytosis and activation/maturation of BMDCs (CD11c⁺CD86⁺, CD11c⁺CD40⁺, CD11c⁺MHCII⁺, IL-6, RNAseq analysis). The tumor prophylactic vaccination model in immune-competent and immune compromised (Rag-2^−/−) mice was used to analyze ferroptosis immunogenicity.

Results

Ferroptosis can be induced in cancer cells by inhibition of glutathione peroxidase 4, as evidenced by confocal and atomic force microscopy and inhibitors’ analysis. We demonstrate for the first time that ferroptosis is immunogenic in vitro and in vivo. Early, but not late, ferroptotic cells promote the phenotypic maturation of BMDCs and elicit a vaccination-like effect in immune-competent mice but not in Rag-2^−/− mice, suggesting that the mechanism of immunogenicity is very tightly regulated by the adaptive immune system and is time dependent. Also, ATP and HMGB1, the best-characterized damage-associated molecular patterns involved in immunogenic cell death, have proven to be passively released along the timeline of ferroptosis and act as immunogenic signal associated with the immunogenicity of early ferroptotic cancer cells.

Conclusions

These results pave the way for the development of new therapeutic strategies for cancers based on induction of ferroptosis, and thus broadens the current concept of immunogenic cell death and opens the door for the development of new strategies in cancer immunotherapy.

New insights into crosstalk between apoptosis and necroptosis co-induced by chlorothalonil and imidacloprid in Ctenopharyngodon idellus kidney cells

Overuse and co-exposure of pesticides have become a public health problem and threat seriously water health and environmental organisms and even humans. Chlorothalonil (CT) and imidacloprid (IMI) are high-selling pesticides worldwide, which can persist in the environment, and present a series of severely toxic effects on non-target animals. However, the effect of co-application on aquatic organisms is unknown. Based on the concept of the toxic unit (TU), toxic interaction of CT and IMI was evaluated and showed the additive and synergistic toxicity on Ctenopharyngodon idellus (grass carp) kidney cell line (CIK cells). Cell death analysis found an obvious increase of the apoptosis and necrosis rates exposed to CT and IMI, and aggravation when applied together. Moreover, CT and IMI co-exposure accelerated the inhibition of CYP450s/ROS/HIF-1α signal, the decline of energy metabolism, mitochondrial dynamics disorder, activation of Bcl2/Bax/Cyt C/Casp3/Casp9 pathway and RIP1/RIP3/MLKL pathway. Bioinformatics analysis showed autophagy, cell response, NOD-like receptor signaling pathway might be affected by co-exposure. In summary, the above results indicate that co-exposure to CT and IMI has synergistic toxicity and aggravates cell death via inhibition of the CYP450s/ROS/HIF-1α signal. These data provide new insights for evaluating the stacking interaction and revealing the toxicological effects of pesticide mixture.

Sodium iodate induces ferroptosis in human retinal pigment epithelium ARPE-19 cells

Sodium iodate (SI) is a widely used oxidant for generating retinal degeneration models by inducing the death of retinal pigment epithelium (RPE) cells. However, the mechanism of RPE cell death induced by SI remains unclear. In this study, we investigated the necrotic features of cultured human retinal pigment epithelium (ARPE-19) cells treated with SI and found that apoptosis or necroptosis was not the major death pathway. Instead, the death process was accompanied by significant elevation of intracellular labile iron level, ROS, and lipid peroxides which recapitulated the key features of ferroptosis. Ferroptosis inhibitors deferoxamine mesylate (DFO) and ferrostatin-1(Fer-1) partially prevented SI-induced cell death. Further studies revealed that SI treatment did not alter GPX4 (glutathione peroxidase 4) expression, but led to the depletion of reduced thiol groups, mainly intracellular GSH (reduced glutathione) and cysteine. The study on iron trafficking demonstrated that iron influx was not altered by SI treatment but iron efflux increased, indicating that the increase in labile iron was likely due to the release of sequestered iron. This hypothesis was verified by showing that SI directly promoted the release of labile iron from a cell-free lysate. We propose that SI depletes GSH, increases ROS, releases labile iron, and boosts lipid damage, which in turn results in ferroptosis in ARPE-19 cells.

Adaptive Mechanisms of Tumor Therapy Resistance Driven by Tumor Microenvironment

Cancer is a disease which frequently has a poor prognosis. Although multiple therapeutic strategies have been developed for various cancers, including chemotherapy, radiotherapy, and immunotherapy, resistance to these treatments frequently impedes the clinical outcomes. Besides the active resistance driven by genetic and epigenetic alterations in tumor cells, the tumor microenvironment (TME) has also been reported to be a crucial regulator in tumorigenesis, progression, and resistance. Here, we propose that the adaptive mechanisms of tumor resistance are closely connected with the TME rather than depending on non-cell-autonomous changes in response to clinical treatment. Although the comprehensive understanding of adaptive mechanisms driven by the TME need further investigation to fully elucidate the mechanisms of tumor therapeutic resistance, many clinical treatments targeting the TME have been successful. In this review, we report on recent advances concerning the molecular events and important factors involved in the TME, particularly focusing on the contributions of the TME to adaptive resistance, and provide insights into potential therapeutic methods or translational medicine targeting the TME to overcome resistance to therapy in clinical treatment.

Deoxypodophyllotoxin Inhibits Non-Small Cell Lung Cancer Cell Growth by Reducing HIF-1α-Mediated Glycolysis

Cancer cell proliferation is a metabolically demanding process that requires high rate of glycolysis to support anabolic growth. Deoxypodophyllotoxin (DPT) is a natural flavonolignan with various pharmacological activities, including antitumor effect. However, whether DPT affects the metabolic reprogramming of cancer cells is unknown. The purpose of this study is to investigate the role of DPT on non-small cell lung cancer (NSCLC) and to explore whether HIF-1α-mediated glycolysis is involved in its mechanism of action.The level of HIF-1α mRNA and protein in NSCLC cells following DPT treatment was detected using qRT-PCR and western blotting, respectively. Cell Counting Kit-8 (CCK-8) and caspase-3 activity assays were performed to analyze cell proliferation and apoptosis. The underlying molecular mechanism was identified by dual luciferase assay, Western blotting, qRT-PCR, glucose consumption, lactate production, and immunoprecipitation. A murine NSCLC model was used to clarify the effect of DPT treatment on tumor cell proliferation. Our findings showed that DPT treatment inhibited NSCLC cell growth in a dose- and time-dependent manner. Further analysis suggested that DPT treatment inhibited HIF-1α signaling pathway by Parkin-mediated protein degradation in NSCLC cells. DPT treatment significantly decreased glucose consumption and lactate production. In addition, DPT treatment reduced the expression of HIF-1α target genes, including GLUT1, HK2 and LDHA, resulting in reduction in glycolysis. We further revealed that DPT-induced cell growth inhibition and increased glucose and lactate levels could be reversed by overexpressing HIF-1α. Additionally, we found that DPT repressed NSCLC growth and GLUT1, HK2 and LDHA expression in vivo. Overall, this study suggested that DPT inhibited NSCLC growth by preventing HIF-1α-mediated glycolysis.

Down-Regulation of Hypoxia-Inducible Factor-1α and Downstream Glucose Transporter Protein-1 Gene by β-elemene Enhancing the Radiosensitivity of Lung Adenocarcinoma Transplanted Tumor

Purpose

To study the effect of β-elemene on the radiosensitivity of A549 cell xenograft tumor and potential mechanisms by which β-elemene regulates the expression of hypoxia-inducible factor-1α (HIF-1α) and glucose transporter protein-1 (GLUT-1).

Methods

Using an A549 cell transplantation tumor model with male nude mice, we studied the effect of β-elemene on the radiosensitivity of non-small cell lung cancer (NSCLC). The expression of HIF-1α and GLUT-1 was detected by real-time PCR, Western blotting and immunohistochemistry. The relationship between the radiosensitivity of β-elemene and the expression of HIF-1α and GLUT-1 was analyzed.

Results

β-elemene and radiotherapy intervened in the growth of transplanted tumors in varying degrees. The enhancement factor (EF=2.44>1) was calculated; β-elemene at 45 mg/kg had the most significant enhanced effect on radiosensitivity. When β-elemene was used in combination with radiation, the expression of HIF-1α and GLUT-1 was significantly decreased, and there was a positive correlation between the two genes.

Conclusion

β-elemene exhibits a radiosensitizing effect on A549 cell xenograft tumor. The underlying molecular mechanism is probably associated with the down-regulation of HIF-1α and GLUT-1 expression, suggesting that β-elemene may directly or indirectly inhibit the expression of HIF-1α and GLUT-1. There is a positive significant correlation between expression of HIF-1α and GLUT-1. HIF-1α and downstream GLUT-1 could be used as a new target for the radiosensitization of NSCLC.

Necroptosis in Intestinal Inflammation and Cancer: New Concepts and Therapeutic Perspectives

Necroptosis is a caspases-independent programmed cell death displaying intermediate features between necrosis and apoptosis. Albeit some physiological roles during embryonic development such tissue homeostasis and innate immune response are documented, necroptosis is mainly considered a pro-inflammatory cell death. Key actors of necroptosis are the receptor-interacting-protein-kinases, RIPK1 and RIPK3, and their target, the mixed-lineage-kinase-domain-like protein, MLKL. The intestinal epithelium has one of the highest rates of cellular turnover in a process that is tightly regulated. Altered necroptosis at the intestinal epithelium leads to uncontrolled microbial translocation and deleterious inflammation. Indeed, necroptosis plays a role in many disease conditions and inhibiting necroptosis is currently considered a promising therapeutic strategy. In this review, we focus on the molecular mechanisms of necroptosis as well as its involvement in human diseases. We also discuss the present developing therapies that target necroptosis machinery.

Targeting necroptosis in anticancer therapy: mechanisms and modulators

Necroptosis, a genetically programmed form of necrotic cell death, serves as an important pathway in human diseases. As a critical cell-killing mechanism, necroptosis is associated with cancer progression, metastasis, and immunosurveillance. Targeting necroptosis pathway by small molecule modulators is emerging as an effective approach in cancer therapy, which has the advantage to bypass the apoptosis-resistance and maintain antitumor immunity. Therefore, a better understanding of the mechanism of necroptosis and necroptosis modulators is necessary to develop novel strategies for cancer therapy. This review will summarize recent progress of the mechanisms and detecting methods of necroptosis. In particular, the relationship between necroptosis and cancer therapy and medicinal chemistry of necroptosis modulators will be focused on.

Necroptosis in Immuno-Oncology and Cancer Immunotherapy

Immune-checkpoint blockers (ICBs) have revolutionized oncology and firmly established the subfield of immuno-oncology. Despite this renaissance, a subset of cancer patients remain unresponsive to ICBs due to widespread immuno-resistance. To "break" cancer cell-driven immuno-resistance, researchers have long floated the idea of therapeutically facilitating the immunogenicity of cancer cells by disrupting tumor-associated immuno-tolerance via conventional anticancer therapies. It is well appreciated that anticancer therapies causing immunogenic or inflammatory cell death are best positioned to productively activate anticancer immunity. A large proportion of studies have emphasized the importance of immunogenic apoptosis (i.e., immunogenic cell death or ICD); yet, it has also emerged that necroptosis, a programmed necrotic cell death pathway, can also be immunogenic. Emergence of a proficient immune profile for necroptosis has important implications for cancer because resistance to apoptosis is one of the major hallmarks of tumors. Putative immunogenic or inflammatory characteristics driven by necroptosis can be of great impact in immuno-oncology. However, as is typical for a highly complex and multi-factorial disease like cancer, a clear cause versus consensus relationship on the immunobiology of necroptosis in cancer cells has been tough to establish. In this review, we discuss the various aspects of necroptosis immunobiology with specific focus on immuno-oncology and cancer immunotherapy.

Distinct patterns of interleukin-12/23 and tumor necrosis factor α synthesis by activated macrophages are modulated by glucose and colon cancer metabolites

Chronic inflammation is a major risk factor for colitis-associated colorectal carcinoma (CRC). Macrophages play a key role in altering the tumor microenvironment by producing pro-inflammatory and anti-inflammatory cytokines. Our previous studies showed that glucose metabolism conferred death resistance for tumor progression and exerted anti-inflammatory effects in ischemic gut mucosa. However, the effect of glucose and cancer metabolites in modulating macrophage cytokine profiles remains poorly defined. We used an in vitro system to mimic intestinal microenvironment and to investigate the roles of glucose and cancer metabolites in the cross-talk between carcinoma cells and macrophages. Human monocyte-derived THP-1 macrophages were stimulated with bacterial lipopolysaccharide (LPS) in the presence of conditioned media (CM) collected from human CRC Caco-2 cells incubated in either glucose-free or glucose-containing media. Our results demonstrated that glucose modulated the macrophage cytokine production, including decreased LPS-induced pro-inflammatory cytokines (i.e., tumor necrosis factor [TNF]α and interleukin [IL]-6) and increased anti-inflammatory cytokine (i.e., IL-10), at resting state. Moreover, glucose-containing CM reduced the macrophage secretion of TNFα and IL-8 but elevated the IL-12 and IL-23 levels, showing an opposite pattern of distinct pro-inflammatory cytokines modulated by cancer glucose metabolites. In contrast, LPS-induced production of macrophage inflammatory protein-1 (a macrophage-derived chemoattractant for granulocytes) was not altered by glucose or CM, indicating that resident macrophages may play a more dominant role than infiltrating granulocytes for responding to cancer metabolites. In conclusion, glucose metabolites from CRC triggered distinct changes in the cytokine profiles in macrophages. The downregulation of death-inducing TNFα and upregulation of Th1/17-polarizing IL-12/IL-23 axis in macrophages caused by exposure to cancer-derived glucose metabolites may contribute to tumor progression.

Glucose Metabolites Exert Opposing Roles in Tumor Chemoresistance

Reprogrammed glucose metabolism and increased glycolysis have been implicated in tumor chemoresistance. The aim was to investigate the distinct roles of the glucose metabolites pyruvate and ATP in chemoresistance mechanisms, including cell death and proliferation. Our data showed higher glucose transporters in colorectal cancer (CRC) from non-responsive patients than those responsive to chemotherapy. Human CRC cell lines exposed to 5-fluorouracil (5-FU) displayed elevated cell viability and larger tumors in xenograft mouse models if cultured in high-glucose medium. Glucose conferred resistance to 5-FU-induced necroptosis via pyruvate scavenging of mitochondrial free radicals, whereas ATP replenishment had no effect on cell death. Glucose attenuated the 5-FU-induced G0/G1 shift but not the S phase arrest. Opposing effects were observed by glucose metabolites; ATP increased while pyruvate decreased the G0/G1 shift. Lastly, 5-FU-induced tumor spheroid destruction was prevented by glucose and pyruvate, but not by ATP. Our finding argues against ATP as the main effector for glucose-mediated chemoresistance and supports a key role of glycolytic pyruvate as an antioxidant for dual modes of action: necroptosis reduction and a cell cycle shift to a quiescent state.

Current translational potential and underlying molecular mechanisms of necroptosis

Cell death has a fundamental impact on the evolution of degenerative disorders, autoimmune processes, inflammatory diseases, tumor formation and immune surveillance. Over the past couple of decades extensive studies have uncovered novel cell death pathways, which are independent of apoptosis. Among these is necroptosis, a tightly regulated, inflammatory form of cell death. Necroptosis contribute to the pathogenesis of many diseases and in this review, we will focus exclusively on necroptosis in humans. Necroptosis is considered a backup mechanism of apoptosis, but the in vivo appearance of necroptosis indicates that both caspase-mediated and caspase-independent mechanisms control necroptosis. Necroptosis is regulated on multiple levels, from the transcription, to the stability and posttranslational modifications of the necrosome components, to the availability of molecular interaction partners and the localization of receptor-interacting serine/threonine-protein kinase 1 (RIPK1), receptor-interacting serine/threonine-protein kinase 3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL). Accordingly, we classified the role of more than seventy molecules in necroptotic signaling based on consistent in vitro or in vivo evidence to understand the molecular background of necroptosis and to find opportunities where regulating the intensity and the modality of cell death could be exploited in clinical interventions. Necroptosis specific inhibitors are under development, but >20 drugs, already used in the treatment of various diseases, have the potential to regulate necroptosis. By listing necroptosis-modulated human diseases and cataloging the currently available drug-repertoire to modify necroptosis intensity, we hope to kick-start approaches with immediate translational potential. We also indicate where necroptosis regulating capacity should be considered in the current applications of these drugs.

Atrazine induces necroptosis by miR-181-5p targeting inflammation and glycometabolism in carp lymphocytes

Atrazine (ATR) causes environmental problems and damages the health of fish and aquatic animals. MicroRNAs (miRNAs) play important roles in immune regulation. However, the immunotoxicity mechanism of ATR in fish lymphocytes and the role of miRNA in this process remain unclear. To further study these mechanisms, spleen lymphocytes were exposed to 20, 40 and 60 μg/ml ATR for 18 h. Fluorescence staining and flow cytometry showed that the number of necrotic lymphocytes increased after ATR exposure. Compared with the control group, the mRNA expression of miR-181-5p was inhibited and the mRNA levels of TNF-α and HK2 were increased after ATR exposure. Additionally, the NF-κB inflammatory pathway and the levels of glycometabolism-related genes were upregulated. These results suggest that ATR induces inflammation and elevates glycometabolism in lymphocytes. We further found that the mRNA levels of receptor-interacting serine-threonine kinase 1 (RIP1), receptor-interacting serine-threonine kinase 3 (RIP3), mixed lineage kinase domain-like pseudokinase (MLKL), cylindromatosis (CYLD) and Fas-Associated protein with Death Domain (FADD) and the protein levels of RIP3 and MLKL in the treatment groups were significantly increased compared to those in control group, suggesting that ATR causes lymphocyte necroptosis. We conclude that miR-181-5p plays a key role in necroptosis in carp lymphocytes exposed to ATR by downregulating the expression of HK and TNF-α, which increases the level of glycometabolism and induces the inflammatory response, respectively.

MLKL contributes to shikonin-induced glioma cell necroptosis via promotion of chromatinolysis

Chromatinolysis refers to enzymatic degradation of nuclear DNA and is regarded as one of the crucial events leading to cell death. Mixed-lineage kinase domain-like protein (MLKL) has been identified as a key executor of necroptosis, but it remains unclear whether MLKL contributes to necroptosis via regulation of chromatinolysis. In this study, we find that shikonin induces MLKL activation and chromatinolysis in glioma cells in vitro and in vivo, which are accompanied with nuclear translocation of AIF and γ-H2AX formation. In vitro studies reveal that inhibition of MLKL with its specific inhibitor NSA or knockdown of MLKL with siRNA abrogates shikonin-induced glioma cell necroptosis, as well as chromatinolysis. Mechanistically, activated MLKL targets mitochondria and triggers excessive generation of mitochondrial superoxide, which promotes AIF translocation into nucleus via causing mitochondrial depolarization and aggravates γ-H2AX formation via improving intracellular accumulation of ROS. Inhibition of nuclear level of AIF by knockdown of AIF with siRNA or mitigation of γ-H2AX formation by suppressing ROS with antioxidant NAC effectively prevents shikonin-induced chromatinolysis. Then, we found that RIP3 accounts for shikonin-induced activation of MLKL, and activated MLKL reversely up-regulates the protein level of CYLD and promotes the activation of RIP1 and RIP3. Taken together, our data suggest that MLKL contributes to shikonin-induced glioma cell necroptosis via promotion of chromatinolysis, and shikonin induces a positive feedback between MLKL and its upstream signals RIP1 and RIP3.

Population Dynamics in Cell Death: Mechanisms of Propagation

Cell death can occur through numerous regulated mechanisms that are categorized by their molecular machineries and differing effects on physiology. Apoptosis and necrosis, for example, have opposite effects on tissue inflammation due to their different modes of execution. Another feature that can distinguish different forms of cell death is that they have distinct intrinsic effects on the cell populations in which they occur. For example, a regulated mechanism of necrosis called ferroptosis has the unusual ability to spread between cells in a wave-like manner, thereby eliminating entire cell populations. Here we discuss the ways in which cell death can propagate between cells in normal physiology and disease, as well as the potential exploitation of cell death propagation for cancer therapy.

Hydrogen Sulfide Gas Exposure Induces Necroptosis and Promotes Inflammation through the MAPK/NF-κB Pathway in Broiler Spleen

Hydrogen sulfide (H2S) is one of the main pollutants in the atmosphere, which is a serious threat to human health. The decomposition of sulfur-containing organics in chicken houses could produce a large amount of H2S, thereby damaging poultry health. In this study, one-day-old broilers were selected and exposed to 4 or 20 ppm of H2S gas (0-3 weeks: 4 ± 0.5 ppm, 4-6 weeks: 20 ± 0.5 ppm). The spleen samples were collected immediately after the chickens were euthanized at 2, 4, and 6 weeks. The histopathological and ultrastructural observations showed obvious necrosis characteristics of H2S-exposed spleens. H2S exposure suppressed GSH, CAT, T-AOC, and SOD activities; increased NO, H2O2, and MDA content and iNOS activity; and induced oxidative stress. ATPase activities and the expressions of energy metabolism-related genes were significantly decreased. Also, the expressions of related necroptosis (RIPK1, RIPK3, MLKL, TAK1, TAB2, and TAB3) were significantly increased, and the MAPK pathway was activated. Besides, H2S exposure activated the NF-κB classical pathway and induced TNF-α and IL-1β release. Taken together, we conclude that H2S exposure induces oxidative stress and energy metabolism dysfunction; evokes necroptosis; activates the MAPK pathway, eventually triggering the NF-κB pathway; and promotes inflammatory response in chicken spleens.

The role of necroptosis in cancer biology and therapy

Apoptosis resistance is to a large extent a major obstacle leading to chemotherapy failure during cancer treatment. Bypassing the apoptotic pathway to induce cancer cell death is considered to be a promising approach to overcoming this problem. Necroptosis is a regulated necrotic cell death modality in a caspase-independent fashion and is mainly mediated by Receptor-Interacting Protein 1 (RIP1), RIP3, and Mixed Lineage Kinase Domain-Like (MLKL). Necroptosis serves as an alternative mode of programmed cell death overcoming apoptosis resistance and may trigger and amplify antitumor immunity in cancer therapy.The role of necroptosis in cancer is complicated. The expression of key regulators of the necroptotic pathway is generally downregulated in cancer cells, suggesting that cancer cells may also evade necroptosis to survive; however, in certain types of cancer, the expression level of key mediators is elevated. Necroptosis can elicit strong adaptive immune responses that may defend against tumor progression; however, the recruited inflammatory response may also promote tumorigenesis and cancer metastasis, and necroptosis may generate an immunosuppressive tumor microenvironment. Necroptosis also reportedly promotes oncogenesis and cancer metastasis despite evidence demonstrating its antimetastatic role in cancer. In addition, necroptotic microenvironments can direct lineage commitment to determine cancer subtype development in liver cancer. A plethora of compounds and drugs targeting necroptosis exhibit potential antitumor efficacy, but their clinical feasibility must be validated.Better knowledge of the necroptotic pathway mechanism and its physiological and pathological functions is urgently required to solve the remaining mysteries surrounding the role of necroptosis in cancer. In this review, we briefly introduce the molecular mechanism and characteristics of necroptosis, the interplay between necroptosis and other cell death mechanisms, crosstalk of necroptosis and metabolic signaling and detection methods. We also summarize the intricate role of necroptosis in tumor progression, cancer metastasis, prognosis of cancer patients, cancer immunity regulation, cancer subtype determination and cancer therapeutics.

Molecular intricacies of aerobic glycolysis in cancer: current insights into the classic metabolic phenotype

Aerobic glycolysis is the process of oxidation of glucose into pyruvate followed by lactate production under normoxic condition. Distinctive from its anaerobic counterpart (i.e. glycolysis that occurs under hypoxia), aerobic glycolysis is frequently witnessed in cancers, popularly known as the "Warburg effect", and it is one of the earliest known evidences of metabolic alteration in neoplasms. Intracellularly, aerobic glycolysis circumvents mitochondrial oxidative phosphorylation (OxPhos), facilitating an increased rate of glucose hydrolysis. This in turn enables cancer cells to successfully compete with normal cells for glucose uptake in order to maintain uninterrupted growth. In addition, evading OxPhos mitigates excessive generation/accumulation of reactive oxygen species that otherwise may be deleterious to cells. Emerging data indicate that aerobic glycolysis in cancer also promotes glutaminolysis to satisfy the precursor requirements of certain biosynthetic processes (e.g. nucleic acids). Next, the metabolic intermediates of aerobic glycolysis also feed the pentose phosphate pathway (PPP) to facilitate macromolecular biosynthesis necessary for cancer cell growth and proliferation. Extracellularly, the extrusion of the end-product of aerobic glycolysis, i.e. lactate, alters the tumor microenvironment, and impacts cancer-associated cells. Collectively, accumulating data unequivocally demonstrate that aerobic glycolysis implicates myriad of molecular and functional processes to support cancer progression. This review, in the light of recent research, dissects the molecular intricacies of its regulation, and also deliberates the emerging paradigms to target aerobic glycolysis in cancer therapy.