Necroptosis regulates tumor repopulation after radiotherapy via RIP1/RIP3/MLKL/JNK/IL8 pathway

GSK'872 Improves Prognosis of Traumatic Brain Injury by Switching Receptor-Interacting Serine/Threonine-Protein Kinase 3-dependent Necroptosis to Cysteinyl Aspartate Specific Proteinase-8-Dependent Apoptosis

BACKGROUND

Traumatic brain injury (TBI) is an important health concern in the society. Previous studies have suggested that necroptosis occurs following TBI. However, the underlying mechanisms and roles of necroptosis are not well understood. In this study, we aimed to assess the role of receptor-interacting serine/threonine-protein kinase 3 (RIP3)-mediated necroptosis after TBI both in vitro and in vivo.

METHODS

We established a cell-stretching injury and mouse TBI model by applying a cell injury controller and controlled cortical impactor to evaluate the relationships among necroptosis, apotosis, inflammation, and TBI both in vitro and in vivo.

RESULTS

The results revealed that necroptosis mediated by RIP1, RIP3, and mixed lineage kinase domain-like protein was involved in secondary TBI. Additionally, protein kinase B (Akt), phosphorylated Akt, mammalian target of rapamycin (mTOR), and phosphorylated mTOR potentially contribute to necroptosis. The inhibition of RIP3 by GSK'872 (a specific inhibitor) blocked necroptosis and reduced the activity of Akt/mTOR, leading to the alleviation of inflammation by reducing the levels of NOD-, LRR- and pyrin domain-containing protein 3. Moreover, the inhibition of RIP3 by GSK'872 promoted the activity of cysteinyl aspartate specific proteinase-8, an enzyme involved in apoptosis and inflammation.

CONCLUSIONS

These data demonstrate that RIP3 inhibition could improve the prognosis of TBI, based on the attenuation of inflammation by switching RIP3-dependent necroptosis to cysteinyl aspartate specific proteinase-8-dependent apoptosis.

cGAS-ISG15-RAGE axis reprogram necroptotic microenvironment and promote lymphatic metastasis in head and neck cancer

BACKGROUND

Cancer cells frequently evolve necroptotic resistance to overcome various survival stress during tumorigenesis. However, we have previously showed that necroptosis is widespread in head and neck squamous cell carcinoma (HNSCC) and contributes to tumor progression and poor survival via DAMPs-induced migration and invasiveness in peri-necroptotic tumor cells. This implicated an alternative strategy that cancers cope with necroptotic stress by reprogramming a pro-invasive necroptotic microenvironment (NME). Here, we aim to decipher how necroptotic cells shape the NME and affect HNSCC progression.

METHODS

Both our pre-established cellular necroptotic model and newly established Dox-induce intratumoral necroptosis model were used to investigate how necroptosis affect HNSCC progression. Transcriptomic alterations in peri-necroptotic tumor cells were analyzed by RNA-seq and validated in the NME in mice and patients' samples. The differential DAMPs compositon among apopotosis. Necrosis, and necroptosis were analyzed by label-free proteomic technique, and the necroptosis-specific DAMPs were then identified and validated. The potential receptor for ISG15 were simulated using molecular docking and further validated by in vitro assays. Then the ISG15-RAGE axis was blocked by either knockdown of necroptotic-ISG15 release and RAGE inhibitor FPS-ZM1, and the impact on tumor progression were tested. Last, we further tested our findings in a HNSCC-patients cohort.

RESULTS

Necroptosis played a crucial role in driving tumor-cell invasiveness and lymphatic metastasis via tumor-type dependent DAMPs-releasing. Mechanistically, necroptotic DAMPs induced peri-necroptotic EMT via NF-κB and STAT3 signaling. Furthermore, intrinsic orchestration between necroptotic and cGAS-STING signaling resulted in producing a group of interferon stimulated genes (ISGs) as HNSCC-dependent necroptotic DAMPs. Among them, ISG15 played an essential role in reprogramming the NME. We then identified RAGE as a novel receptor for extracellular ISG15. Either blockage of ISG15 release or ISG15-RAGE interaction dramatically impeded necroptosis-driven EMT and lymphatic metastasis in HNSCC. Lastly, clinicopathological analysis showed high ISG15 expression in NME. Extensive necroptosis and high tumor-cell RAGE expression correlated with tumor progression and poor survival of HNSCC patients.

CONCLUSIONS

Our data revealed a previously unknown cGAS-ISG15-RAGE dependent reprogramming of the necroptotic microenvironment which converts the necroptotic stress into invasive force to foster HNSCC-cell dissemination. By demonstrating the programmatic production of ISG15 via necroptosis-cGAS orchestration and its downstream signaling through RAGE, we shed light on the unique role of ISG15 in HNSCC progression. Targeting such machineries may hold therapeutic potential for restoring intratumoral survival stress and preventing lymphatic metastasis in HNSCC.

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.

Naringenin reduces oxidative stress and necroptosis, apoptosis, and pyroptosis in random-pattern skin flaps by enhancing autophagy

BACKGROUND

Random skin flap grafting is one of the most commonly used techniques in plastic and orthopedic surgery. However, necrosis resulting from ischemia and ischemia-reperfusion injury in the distal part of the flap can severely limit the clinical application of the flap. Studies have revealed that naringenin reduces pyroptosis, apoptosis, and necroptosis, inhibits oxidative stress, and promotes autophagy. In this study, the effects of Naringenin on flap viability and its underlying mechanism were evaluated.

METHODS

Mice with random skin flaps were randomly allocated to control, Naringenin, and Naringenin + 3-methyladenine groups. On postoperative day 7, flap tissues were collected to estimate angiogenesis, necroptosis, apoptosis, pyroptosis, oxidative stress, and autophagy via hematoxylin and eosin staining, immunofluorescence, and immunohistochemistry.

RESULTS

The results revealed that naringenin promoted the viability of the random flaps as well as angiogenesis, while inhibiting oxidative stress and decreasing pyroptosis, apoptosis, and necroptosis. These effects were reversed by the autophagy inhibitor 3-methyladenine.

CONCLUSIONS

The findings indicated that naringenin treatment could promote flap survival by inhibiting pyroptosis, apoptosis, necroptosis, and alleviating oxidative stress, caused by the activation of autophagy.

HIST3H2A promotes the progression of prostate cancer through inhibiting cell necroptosis

In recent years, there has been an increase in the incidence and mortality rates of prostate cancer (PCa). However, the specific molecular mechanisms underlying its occurrence and development remain unclear, necessitating the identification of new therapeutic targets. Through bioinformatics analysis, we discovered a previously unstudied differential gene called HIST3H2A in prostate cancer. Our study revealed that HIST3H2A is highly expressed in PCa tissues, as confirmed by analysis of both the GEO and UALCAN databases. Further analysis using the KEGG database demonstrated that HIST3H2A regulates the pathway of programmed necroptosis in cells. Additionally, we observed significant up-regulation of HIST3H2A in PCa tissues and cell lines. HIST3H2A was found to regulate cell proliferation, migration, invasion, and the epithelial-mesenchymal transition (EMT) process in tumors. Notably, HIST3H2A's role in regulating programmed necroptosis in prostate cancer cells differs from its role in apoptosis. In vitro and in vivo experiments collectively support the key role of HIST3H2A in promoting the development of prostate cancer, highlighting its potential as a therapeutic target for patients with PCa.

Exosomal SOX21-AS1 Regulates EREG by Sponging miR-451a and Promotes the Malignancy of Pancreatic Ductal Adenocarcinoma

The incidence and mortality of pancreatic ductal adenocarcinoma (PDAC) have increased. Exosomes, as a regulatory mode of intercellular communication, contain lncRNAs. SOX21-AS1 has been studied in other cancers, and its expression is elevated in PDAC, but its role in PDAC remains unclear. First, we analyzed the expression of lncRNAs in PDAC tissues and nontumor tissues through the TCGA database. Next, the results of the RT-qPCR experiment confirmed the prediction that the expression of SOX21-AS1 was elevated in PDAC tissues. In vivo and in vitro cell function assays confirmed that the degree of malignancy of PDAC was proportional to the expression of SOX21-AS1. In addition, through exosome isolation and uptake experiments, we first found that PDAC could secrete exosomal SOX21-AS1 and play an angiogenic role in HUVECs. Subsequently, the relationship between SOX21-AS1, miR-451a and epiregulin (EREG) was verified through database prediction and analysis and RIP assays. Finally, functional recovery assays in vivo and in vitro verified that SOX21-AS1 regulates the expression of EREG through combination with miR-451a and thus promotes the malignancy of PDAC. SOX21-AS1 was upregulated in PDAC. The upregulation of SOX21-AS1 can stimulate the proliferation, migration, invasion, stemness and epithelial-mesenchymal transition (EMT) progression of PDAC cells. Furthermore, PDAC cells secrete exosomal SOX21-AS1, which is absorbed by HUVECs and promotes angiogenesis. Our study first identified that SOX21-AS1 promotes the malignancy of PDAC through the SOX21-AS1/miR-451a/EREG axis, and also that exosomal SOX21-AS1 promotes angiogenesis in PDAC.

[The Miao medicine Sidaxue alleviates rheumatoid arthritis in rats possibly by downregulating matrix metalloproteinases]

OBJECTIVE

To explore the inhibitory effect of Sidaxue, a traditional Miao herbal medicine formula, on articular bone and cartilage destruction and synovial neovascularization in rats with collagen-induced arthritis (CIA).

METHODS

In a SD rat model of CIA, we tested the effects of daily gavage of Sidaxue at low, moderate and high doses (10, 20, and 40 g/kg, respectively) for 21 days, with Tripterygium glycosides (GTW) as the positive control, on swelling in the hind limb plantar regions by arthritis index scoring. Pathologies in joint synovial membrane of the rats were observed with HE staining, and serum TNF-α and IL-1β levels were detected with ELISA. The expressions of NF-κB p65, matrix metalloproteinase 1 (MMP1), MMP2 and MMP9 at the mRNA and protein levels in the synovial tissues were detected using real-time PCR and Western blotting. Network pharmacology analysis was conducted to identify the important target proteins in the pathways correlated with the therapeutic effects of topical Sidaxue treatment for RA, and the core target proteins were screened by topological analysis.

RESULTS

Treatment with GTW and Sidaxue at the 3 doses all significantly alleviated plantar swelling, lowered arthritis index scores, improved cartilage and bone damage and reduced neovascularization in CIA rats (P<0.05), and the effects of Sidaxue showed a dose dependence. Both GTW and Sidaxue treatments significantly lowered TNF-α, IL-1β, NF-κB p65, MMP1, MMP2, and MMP9 mRNA and protein expressions in the synovial tissues of CIA rats (P<0.05). Network pharmacological analysis identified MMPs as the core proteins associated with topical Sidaxue treatment of RA.

CONCLUSION

Sidaxue alleviates articular bone and cartilage damages and reduces synovial neovascularization in CIA rats possibly by downregulating MMPs via the TNF-α/IL-1β/NF-κB-MMP1, 2, 9 signaling pathway, and MMPs probably plays a key role in mediating the effect of Sidaxue though the therapeutic pathways other than oral administration.

Crosstalk between metabolism and cell death in tumorigenesis

It is generally recognized that tumor cells proliferate more rapidly than normal cells. Due to such an abnormally rapid proliferation rate, cancer cells constantly encounter the limits of insufficient oxygen and nutrient supplies. To satisfy their growth needs and resist adverse environmental events, tumor cells modify the metabolic pathways to produce both extra energies and substances required for rapid growth. Realizing the metabolic characters special for tumor cells will be helpful for eliminating them during therapy. Cell death is a hot topic of long-term study and targeting cell death is one of the most effective ways to repress tumor growth. Many studies have successfully demonstrated that metabolism is inextricably linked to cell death of cancer cells. Here we summarize the recently identified metabolic characters that specifically impact on different types of cell deaths and discuss their roles in tumorigenesis.

Phytocompounds-based therapeutic approach: Investigating curcumin and green tea extracts on MCF-7 breast cancer cell line

BACKGROUND

Breast cancer (BC) has transcended lung cancer as the most common cancer in the world. Due to the disease's aggressiveness, rapid growth, and heterogeneity, it is crucial to investigate different therapeutic approaches for treatment. According to the World Health Organization (WHO), Plant-based therapeutics continue to be utilized as safe/non-toxic complementary or alternative treatments for cancer, even in developed countries, regardless of how cutting-edge conventional therapies are. Despite their low bioavailability, curcumin (CUR) and green tea (GT) represent safer therapeutic options. Due to their potent molecular-modulating properties on various cancer-related molecules and signaling pathways, they are considered gold-standard therapeutic agents and have been incorporated into the development of one or more therapeutic strategies of BC treatment.

METHODS

We investigated the modulatory role of CUR and GT extracts on significant multi molecular targets in MCF-7 BC cell line to assess their potential as BC multi-targeting agents. We analyzed the phytocompounds in GT leaves using High-performance liquid chromatography (HPLC) and Gas chromatography-mass spectrometry (GC-MS) techniques. The mRNA expression levels of Raf-1, Telomerase, Tumor necrosis factor alpha (TNF-α) and Interleukin-8 (IL-8) genes in MCF-7 cells were quantified using quantitative real-time PCR (qRT-PCR). The cytotoxicity of the extracts was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the released Lactate dehydrogenase (LDH), a valuable marker for identifying the programmed necrosis (necroptosis). Additionally, the concentrations of the necroptosis-related proinflammatory cytokines (TNF-α and IL-8) were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

In contrast to the GT, the results showed the anticancer and cytotoxic properties of CUR against MCF-7 cells, with a relatively higher level of released LDH. The CUR extract downregulated the oncogenic Raf-1, suppressed the Telomerase and upregulated the TNF-α and IL-8 genes. Results from the ELISA showed a notable increase in IL-8 and TNF-α cytokines levels after CUR treatment, which culminated after 72 h.

CONCLUSIONS

Among both extracts, only CUR effectively modulated the understudy molecular targets, achieving multi-targeting anticancer activity against MCF-7 cells. Moreover, the applied dosage significantly increased levels of the proinflammatory cytokines, which represent a component of the cytokines-targeting-based therapeutic strategy. However, further investigations are recommended to validate this therapeutic approach.

Tryptophan alleviates intestinal damage through regulating necroptosis and TLR4/NOD signaling pathways in pigs after lipopolysaccharide challenge

This study aimed to test the hypothesis that necroptosis, toll-like receptor 4 (TLR4)/nucleotide-binding oligomerization domain (NOD) signaling pathway in the jejunum of lipopolysaccharide (LPS)-challenged piglets are involved in the alleviation of intestinal injury and inflammation by tryptophan supplementation. Tryptophan supplementation has improved intestinal morphology. Also, tryptophan has been found to increase the mRNA and protein expression of tight junction proteins and decrease the expression of pro-inflammatory cytokines. Dietary tryptophan decreased the mRNA expression of heat shock protein 70, TLR4, NOD1, NOD2, myeloid differentiation primary response gene 88, interleukin 1 receptor-associated kinase 1, TNF receptor-associated factor 6, receptor-interacting serine/threonine-protein kinase 2-like, nuclear factor-kappaB transcription factor P65 in the jejunum of piglets. Tryptophan alleviated LPS-induced necroptosis and decreased the mRNA expression of mixed lineage kinase domain-like, receptor-interacting serine/threonine kinase 1, receptor-interacting serine/threonine-protein kinase 3-like, Fas (TNFRSF6)-associated via death domain, PGAM family member 5. Collectively, our results suggest that tryptophan supplementation helps in the attenuation of intestinal injury and inflammation by alleviating necroptosis and TLR4/NOD in lipopolysaccharide-challenged pigs.

Targeting Neutrophil Extracellular Traps: A Novel Antitumor Strategy

The clinical efficacy of surgery, radiotherapy, and chemotherapy for cancer is usually limited by the deterioration of tumor microenvironment (TME). Neutrophil extracellular traps (NETs) are decondensed chromatin extruded by neutrophils and are widely distributed among various cancers, such as pancreatic cancer, breast cancer, and hepatocellular carcinoma. In the TME, NETs interact with stromal components, immune cells and cancer cells, which allows for the reshaping of the matrix and the extracellular environment that favors the initiation, progression, and metastasis of cancer. In addition, NETs impair the proliferation and activation of T cells and NK cells, thus producing a suppressive TME that restricts the effect of immunotherapy. A better understanding of the function of NETs in the TME will provide new opportunities for the prevention of cancer metastasis and the discovery of novel therapy strategies.

A systematic framework for identifying prognostic necroptosis-related lncRNAs and verification of lncRNA CRNDE/miR-23b-3p/IDH1 regulatory axis in glioma

Glioma remains the most frequent malignancy of the central nervous system. Recently, necroptosis has been identified as a cell death process that mediates the proliferation and development of tumor cells. LncRNAs play a key role in the diagnosis and treatment of various diseases. However, the impact that necrosis-related lncRNAs (NRLs) have on glioma remains unclear. In our studies, we selected 9 NRLs to construct a prognostic model. Meanwhile, we assessed the survival curves of these 9 NRLs. Our findings found ADGRA1-AS1 and WAC-AS1 were protective lncRNAs, while MIR210HG, LINC01503, CRNDE, HOXC-AS1, ZIM2-AS1, MIR22HG and PLBD1-AS1 were risk lncRNAs. Specifically, 12 immune cells, 25 immune-correlated pathways, and TME score were differentially expressed in the both risk groups. Additionally, the study predicted and validated the necroptosis-related lncRNA CRNDE/miR-23b-3p/IDH1 axis. CRNDE was strongly expressed in glioma specimens and several cell lines. Inhibiting CRNDE resulted in a substantial reduction in the proliferation and migration of U-118MG and U251 cells. Furthermore, the study predicted that CRNDE may exhibit oncogenic features by adsorbing miR-23b-3p and positively regulating IDH1 expression. Overall, the study constructed a prognostic model in glioma, and predicted a lncRNA CRNDE/miR-23b-3p/IDH1 axis, which could potentially be useful for gene therapy of glioma.

The dual role of citrate in cancer

Citrate is a key metabolite of the Krebs cycle that can also be exported in the cytosol, where it performs several functions. In normal cells, citrate sustains protein acetylation, lipid synthesis, gluconeogenesis, insulin secretion, bone tissues formation, spermatozoid mobility, and immune response. Dysregulation of citrate metabolism is implicated in several pathologies, including cancer. Here we discuss how cancer cells use citrate to sustain their proliferation, survival, and metastatic progression. Also, we propose two paradoxically opposite strategies to reduce tumour growth by targeting citrate metabolism in preclinical models. In the first strategy, we propose to administer in the tumor microenvironment a high amount of citrate, which can then act as a glycolysis inhibitor and apoptosis inducer, whereas the other strategy targets citrate transporters to starve cancer cells from citrate. These strategies, effective in several preclinical in vitro and in vivo cancer models, could be exploited in clinics, particularly to increase sensibility to current anti-cancer agents.

[Liposome nanoparticles for targeted delivery of parthenolide induce colorectal cancer necroptosis to ameliorate tumor-infiltrating T cell exhaustion in mice]

OBJECTIVE

To investigate the mechanism of parthenolide for inducing necroptosis and ameliorating CD8+ T cell exhaustion in colorectal cancer (CRC) and construct liposome nanoparticles for targeted delivery of parthenolide.

METHODS

The inhibitory effect of parthenolide on proliferation of different CRC cell lines was examined using CCK8 assay, and ROS LDH detection and Western blotting were used to analyze the cell death pathways. In a mouse model bearing subcutaneous MC38 cell xenografts, the effects of 5 and 15 mg/kg parthenolide on tumor growth and CD8+ T cell depletion were observed. In a mouse model bearing orthotopic CRC cell xenograft in the ileocecal region, free parthenolide (100 μg/mL) or low (100 μg/mL) and high doses (200 μg/mL) of liposome nanoparticles loaded with parthenolide were injected via the tail vein, and the changes in CD8 expression in the xenografts were analyzed using immunohistochemistry.

RESULTS

Treatment with parthenolide dose-dependently lowered the viability of the CRC cell lines SW480, DLD1, HCT116 and MC38 cells, and its effect was obviously antagonized by Nec-1. Immunoblotting analysis showed that parthenolide treatment resulted in increased RIP3 and MLKL phosphorylation in the CRC cells. In the mouse model bearing subcutaneous xenografts, parthenolide treatment at the high dose, but not at the low dose, significantly increased the number of infiltrating CD3+ CD8+ T cells and PD1hiTIM3+ T cell percentage (P<0.01) and lowered the percentage of PD1loTIM3- T cells in the tumor tissue (P<0.01). In the mouse models bearing orthotopic CRC xenograft, intravenous injection of the liposomes loaded with parthenolide, especially at the high dose, significantly increased CD8 expression in the tumor tissue (P<0.01).

CONCLUSION

Parthenolide induces necroptosis in CRC and increases infiltrating CD8+ T cells to ameliorate CD8+ T cell exhaustion in the tumor. Liposome nanoparticles for targeted delivery of parthenolide produce stronger, anti-tumor effect.

Prognostic Value of Necroptosis-Related Genes Signature in Oral Squamous Cell Carcinoma

The dual role of necroptosis in inhibiting and promoting tumor development has gradually received much attention because of its essential significance for targeted treatment. Accordingly, this study aims to explore the relationship between necroptosis and oral squamous cell carcinoma (OSCC), and search for novel prognostic factors for OSCC. RNA-seq data and clinical information were downloaded from TCGA and GTEx databases. The prognostic signature of necroptosis-related genes (NRGs) was constructed by univariate Cox regression analysis and the LASSO Cox regression model. Moreover, survival analyses, ROC curves, and nomograms were adopted to further analyze. GO and KEGG analyses and immune infiltration analyses were used for function enrichment and immune feature research in turn. The NRG prognostic signature expression was higher in OSCC tissues than in normal tissues, and the overall survival (OS) rate of the high-expression group was much lower. HPRT1 was proved to be an independent prognostic factor in OSCC. Furthermore, the function enrichment analyses revealed that NRGs were involved in necroptosis, apoptosis, inflammation, and immune reaction. The expression of NRGs was related to immunosuppression in OSCC. Furthermore, the knockdown of HPRT1 could suppress the proliferation and migration of OSCC. In conclusion, the high expression of NRG prognostic signature is associated with poor prognosis in OSCC, and HPRT1 can serve as a novel independent prognostic factor for OSCC.

Ferroptosis, Necroptosis, and Pyroptosis in Gastrointestinal Cancers: The Chief Culprits of Tumor Progression and Drug Resistance

In recent years, the incidence of gastrointestinal cancers is increasing, particularly in the younger population. Effective treatment is crucial for improving patients' survival outcomes. Programmed cell death, regulated by various genes, plays a fundamental role in the growth and development of organisms. It is also critical for maintaining tissue and organ homeostasis and takes part in multiple pathological processes. In addition to apoptosis, there are other types of programmed cell death, such as ferroptosis, necroptosis, and pyroptosis, which can induce severe inflammatory responses. Notably, besides apoptosis, ferroptosis, necroptosis, and pyroptosis also contribute to the occurrence and development of gastrointestinal cancers. This review aims to provide a comprehensive summary on the biological roles and molecular mechanisms of ferroptosis, necroptosis, and pyroptosis, as well as their regulators in gastrointestinal cancers and hope to open up new paths for tumor targeted therapy in the near future.

Triple‑negative breast cancer cells that survive ionizing radiation exhibit an Axl‑dependent aggressive radioresistant phenotype

This study aimed to investigate the aggressive behavior of triple-negative breast cancer (TNBC) cells that had survived ionizing radiation and explore the potential targets of TNBC combination treatment. Consistent with the previous literature, Axl was highly expressed in TNBC and closely associated with the degree of malignancy based on immunohistochemical staining. Using a gradient irradiation method, the ionizing radiation-resistant mouse TNBC cell line 4T-1/IRR was established. It was found that Axl expression was upregulated in 4T-1/IRR cells. After irradiation by X-ray, the cell viability and colony formation ability of 4T-1/IRR cells were significantly increased when compared with the 4T-1 cells. Combined radiotherapy with Axl inhibition by treatment with R428 and small interfering RNA lentivirus targeting Axl infection significantly reduced cell viability, colony formation ability, DNA double-stranded break repair, and the invasive and migratory ability of 4T-1/IRR cells. In vivo, the small animal radiation research platform was applied to precisely administer radiotherapy of the tumor-bearing mice. R428 treatment combined with 6 Gy X-ray significantly inhibited the growth of 4T-1/IRR cells-derived xenograft tumors in the BALB/c mouse. The results of western blotting showed that the critical molecular mechanism involved in the radioresistance of TNBC cells was the PI3K/Akt/mTOR signaling pathway induced by Axl activation. Thus, it is hypothesized that targeted Axl therapy combined with radiotherapy may have significant potential for the treatment of TNBC.

Can pyroptosis be a new target in rheumatoid arthritis treatment?

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease of undefined etiology, with persistent synovial inflammation and destruction of articular cartilage and bone. Current clinical drugs for RA mainly include non-steroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, disease modifying anti-rheumatic drugs (DMARDs) and so on, which can relieve patients' joint symptoms. If we want to have a complete cure for RA, there are still some limitations of these drugs. Therefore, we need to explore new mechanisms of RA to prevent and treat RA radically. Pyroptosis is a newly discovered programmed cell death (PCD) in recent years, which is characterized by the appearance of holes in cell membranes, cell swelling and rupture, and the release of intracellular pro-inflammatory factors into the extracellular space, resulting in a strong inflammatory response. The nature of pyroptosis is pro-inflammatory, and whether it is participating in the development of RA has attracted a wide interest among scholars. This review describes the discovery and mechanism of pyroptosis, the main therapeutic strategies for RA, and the role of pyroptosis in the mechanism of RA development. From the perspective of pyroptosis, the study of new mechanisms of RA may provide a potential target for the treatment of RA and the development of new drugs in the clinics.

LncRNAs and regulated cell death in tumor cells

Regulated Cell Death (RCD) is a mode of cell death that occurs through drug or genetic intervention. The regulation of RCDs is one of the significant reasons for the long survival time of tumor cells and poor prognosis of patients. Long non-coding RNAs (lncRNAs) which are involved in the regulation of tumor biological processes, including RCDs occurring on tumor cells, are closely related to tumor progression. In this review, we describe the mechanisms of eight different RCDs which contain apoptosis, necroptosis, pyroptosis, NETosis, entosis, ferroptosis, autosis and cuproptosis. Meanwhile, their respective roles in the tumor are aggregated. In addition, we outline the literature that is related to the regulatory relationships between lncRNAs and RCDs in tumor cells, which is expected to provide new ideas for tumor diagnosis and treatment.

Ferroptosis, necroptosis, and pyroptosis in cancer: Crucial cell death types in radiotherapy and post-radiotherapy immune activation

Tumor cell death and antitumor immune activation induced by radiotherapy are extensively well-studied. While radiotherapy is believed to mainly induce tumor cell necrosis and apoptosis, recent studies have shown that it can also induce ferroptosis, necroptosis, and pyroptosis in tumor cells. However, studies on the role of ferroptosis, necroptosis, and pyroptosis in radiotherapy and post-radiotherapy immune activation are limited. In this review, we summarize the comprehensive literature on the molecular mechanisms and more recent research progress related to radiotherapy-induced ferroptosis, necroptosis, and pyroptosis in tumor cells. Further, we discuss the role of tumor cells undergoing these types of cell death in immune activation after radiotherapy. In addition, we highlight some unresolved questions on the association of radiotherapy with ferroptosis, necroptosis, and pyroptosis. This review can improve our current understanding of the relationship between radiotherapy and different cell death pathways and provide a theoretical framework to improve the therapeutic effect of tumor radiotherapy in the future.

Photodynamic Therapy Can Modulate the Nasopharyngeal Carcinoma Microenvironment Infected with the Epstein-Barr Virus: A Systematic Review and Meta-Analysis

Nasopharyngeal carcinoma is a malignancy from epithelial cells predominantly associated with the Epstein-Barr virus (EBV) infection, and it is responsible for 140,000 deaths annually. There is a current need to develop new strategies to increase the efficacy of antineoplastic treatment and reduce side effects. Thus, the present study aimed to perform a systematic review and meta-analysis of the ability of photodynamic therapy (PDT) to modulate the tumor microenvironment and PDT efficacy in nasopharyngeal carcinoma treatment. The reviewers conducted all steps in the systematic review. PubMed, Science Direct, Scopus, Scielo, Lilacs, EMBASE, and the Cochrane library databases were searched. The OHAT was used to assess the risk of bias. Meta-analysis was performed with a random-effects model (α = 0.05). Nasopharyngeal carcinoma cells treated with PDT showed that IL-8, IL-1α, IL-1β, LC3BI, LC3BII, MMP2, and MMP9 levels were significantly higher than in groups that did not receive PDT. NF-ĸB, miR BART 1-5p, BART 16, and BART 17-5p levels were significantly lower in the PDT group than in the control group. Apoptosis levels and the viability of nasopharyngeal carcinoma cells (>70%) infected with EBV were effective after PDT. This treatment also increased LMP1 levels (0.28-0.50/p < 0.05) compared to the control group. PDT showed promising results for efficacy in killing nasopharyngeal carcinoma cells infected with EBV and modulating the tumor microenvironment. Further preclinical studies should be performed to validate these results.

Chemotherapeutic drugs-induced pyroptosis mediated by gasdermin E promotes the progression and chemoresistance of pancreatic cancer

Pyroptosis is closely associated with cancer development; however, the role of pyroptosis in pancreatic ductal adenocarcinoma (PDAC), a fatal malignant tumour with a poor overall survival rate, remains elusive. Here, we explored the mechanism of chemotherapy-induced pyroptosis and elucidated the role of pyroptosis in mediating PDAC progression and chemoresistance. The results demonstrated first- and second-line chemotherapeutic drugs against PDAC, including gemcitabine, irinotecan, 5-fluorouracil, paclitaxel, and cisplatin, induced concurrent pyroptosis and apoptosis. During this process, gasdermin E (GSDME) was cleaved by activated caspase-3, which was accompanied by pro-apoptotic caspase-7/8 activation. GSDME knockdown switched pyroptosis to apoptosis, decreased invasion and migration, and enhanced the sensitivity of PDAC cells to chemotherapy in vitro and in vivo. GSDME was highly expressed in PDAC tissues and positively correlated with histological differentiation and vascular invasion. Furthermore, cells that survived pyroptosis promoted proliferation and invasion and impaired the chemosensitivity of PDAC cells, which was attenuated by the GSDME knockdown. Our findings demonstrated that chemotherapeutics against PDAC induce GSDME-dependent pyroptosis, and GSDME expression positively correlated with PDAC progression and chemoresistance. Targeting GSDME may be a novel approach to overcoming chemoresistance in PDAC.

Interleukin 8 in plasma is an efficacy marker for advanced non-small cell lung cancer treated with hypofractionated radiotherapy and PD-1 blockade

BACKGROUND

Programmed death-1 (PD-1) blockade promotes combination therapy in advanced non-small cell lung cancer (NSCLC), hypofractionated radiotherapy (HFRT) and chemotherapy combined with immunotherapy improves the outcome of prognosis in advanced NSCLC, while effective biomarkers to follow prognostic efficacy are still to be found.

METHODS

We enrolled 44 NSCLC patients with HFRT combined with PD-1 blockade, 13 patients with chemotherapy combined with immunotherapy, additionally collected tissue samples from 8 patients with earlystage NSCLC without therapy, and peripheral whole blood from 16 healthy donors, detected the expression differences of cytokines Interleukin 6 (IL-6), Interleukin 8 (IL-8) and Interleukin 17A (IL-17A) in the peripheral plasma and tissues by flow cytometry, immunofluorescence, and real-time fluorescence quantitative PCR. Cultured peripheral blood mononuclear cell (PBMC) and tumor-infiltrating T cells with recombinant human IL-8 in vitro to observe the changes of immune memory T cell subtypes and apoptosis.

RESULTS

Our results show that IL-6, IL-8, and IL-17A are highly expressed in advanced NSCLC, high levels of IL-8 are significantly associated with poor prognosis in advanced NSCLC patients treated with HFRT + PD1 blockade, high circulating IL-8 in NSCLC increased apoptosis of effector memory RA (TemRA; CD45RA⁺CCR7^-) T cell subsets and CD8⁺ T cell subsets in tissues, resulting in decreased peripheral TemRA and stem cell-like memory T cells (TSCM: CD45RA ⁺CCR7 ⁺ CD95 ⁺) in tissue.

CONCLUSION

We suggest that IL-8 can impair immune memory function in NSCLC. It is a useful biomarker to evaluate the efficacy of HFRT + PD1 blockade in advanced NSCLC. Further exploration of easily available plasma biomarkers for personalized treatment of NSCLC is required.

Progress in study on the final executor of necroptosis MLKL and its inhibitors

Necroptosis is one of the regulated cell death, which involves receptor interacting protein kinase (RIPK) 1/RIPK3/mixed lineage kinase domain like protein (MLKL) signaling pathway. Among them, MLKL is the final execution of necroptosis. The formation of RIPK1/RIPK3/MLKL necrosome induces the phosphorylated MLKL, and the activated MLKL penetrates into the membrane bilayer to form membrane pores, which damages the integrity of the membrane and leads to cell death. In addition to participating in necroptosis, MLKL is also closely related to other cell death, such as NETosis, pyroptosis, and autophagy. Therefore, MLKL is involved in the pathological processes of various diseases related to abnormal cell death pathways (such as cardiovascular diseases, neurodegenerative diseases and cancer), and may be a therapeutic target of multiple diseases. Understanding the role of MLKL in different cell death can lay a foundation for seeking various MLKL-related disease targets, and also guide the development and application of MLKL inhibitors.

HMGB1/TLR4 signaling pathway enhances abdominal aortic aneurysm progression in mice by upregulating necroptosis

OBJECTIVE AND DESIGN

The age-associated increases in aseptic inflammation and necroptosis are closely related to the emergence of various age-associated diseases.

METHODS

In this study, the role of HMGB1/TLR4-induced necroptosis in abdominal aortic aneurysm (AAA) formation was investigated. First, the levels of sterile inflammatory mediators (HMGB1, TLR4) and necroptosis markers were measured in the abdominal aortas of young and old C57BL/6JNifdc mice. We observed that sterile inflammatory mediators and necroptosis markers were greatly increased in the abdominal aortas of old mice. Then, angiotensin II (Ang II)-induced AAA model in APOE^-/- mice was used in this study. Mice AAA models were treated with the RIP1 inhibitor necrostatin-1 (Nec-1) or the TLR4 inhibitor TAK-242, respectively.

RESULTS

We found that HMGB1, TLR4, and necroptosis markers were elevated in old mice compared with those in young mice. Same elevation was also found in the development of AAA in APOE^-/- mice. In addition, the necroptosis inhibitor Nec-1 alleviated Ang II-induced AAA development while downregulating the expression of HMGB1/TLR4. After blocking TLR4 with TAK-242, the expression of necroptosis markers decreased significantly, and the progression of AAA was also alleviated in APOE^-/- mice.

CONCLUSIONS

Our results indicated that HMGB1/TLR4-mediated necroptosis enhances AAA development in the Ang II-induced AAA model in APOE^-/- mice and that TLR4 might be a potential therapeutic target for AAA management.

Mechanosensitive channel MscL induces non-apoptotic cell death and its suppression of tumor growth by ultrasound

Mechanosensitive channel of large conductance (MscL) is the most thoroughly studied mechanosensitive channel in prokaryotes. Owing to its small molecular weight, clear mechanical gating mechanism, and nanopore forming ability upon opening, accumulating studies are implemented in regulating cell function by activating mechanosensitive channel of large conductance in mammalian cells. This study aimed to investigate the potentials of mechanosensitive channel of large conductance as a nanomedicine and a mechano-inducer in non-small cell lung cancer (NSCLC) A549 cells from the view of molecular pathways and acoustics. The stable cytoplasmic vacuolization model about NSCLC A549 cells was established via the targeted expression of modified mechanosensitive channel of large conductance channels in different subcellular organelles. Subsequent morphological changes in cellular component and expression levels of cell death markers are analyzed by confocal imaging and western blots. The permeability of mitochondrial inner membrane (MIM) exhibited a vital role in cytoplasmic vacuolization formation. Furthermore, mechanosensitive channel of large conductance channel can be activated by low intensity focused ultrasound (LIFU) in A549 cells, and the suppression of A549 tumors in vivo was achieved by LIFU with sound pressure as low as 0.053 MPa. These findings provide insights into the mechanisms underlying non-apoptotic cell death, and validate the nanochannel-based non-invasive ultrasonic strategy for cancer therapy.

Comprehensive analysis illustrating the role of PANoptosis-related genes in lung cancer based on bioinformatic algorithms and experiments

Background: Recently, PANoptosis has aroused the interest of researchers for its role in cancers. However, the studies that investigated PANoptosis in lung cancer are still few. Methods: The public data were mainly collected from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus database. R software was utilized for the analysis of public data. Quantitative real-time (qRT) polymerase chain reaction (PCR) was used to measure the RNA level of FADD. The cell proliferation ability was evaluated using the CCK8, colony formation, and 5-ethynyl-2'-deoxyuridine (EdU) assays. Western blot was used to detect the protein level of specific molecules. Flow cytometry analysis and TUNEL staining were used to evaluate cell apoptosis. Results: In our study, we collected the PANoptosis-related genes from previous studies. Through series analysis, we identified the FADD, an adaptor of PANoptosis and apoptosis, for further analysis. Results showed that FADD is one of the prominent risk factors in lung cancer, mainly localized in nucleoplasm and cytosol. We next performed immune infiltration analysis and biological enrichment to illustrate the underlying cause of FADD in lung cancer. Subsequently, we discovered that the patients with a high level of FADD might respond worse to immunotherapy but better to AICAR, bortezomib, docetaxel, and gemcitabine. In vitro experiments indicated that inhibiting FADD could reduce significantly the ability of cancerous lung cells to proliferate. Meanwhile, we found that the knockdown of FADD promotes the apoptosis and pyroptosis. Ultimately, a prognosis signature was identified based on the FADD-regulated genes, which showed satisfactory prediction efficiency on patients with lung cancer. Conclusion: Our result can provide a novel direction for future studies focused on the role of PANoptosis in lung cancer.

Targeting Cell Membranes, Depleting ROS by Dithiane and Thioketal-Containing Polymers with Pendant Cholesterols Delivering Necrostatin-1 for Glaucoma Treatment

Glaucoma is the leading cause of irreversible blindness worldwide, characterized by progressive vision loss due to the selective damage to retinal ganglion cells (RGCs) and their axons. Oxidative stress is generally believed as one key factor of RGCs death. Recently, necroptosis was identified to play a key role in glaucomatous injury. Therefore, depletion of reactive oxygen species (ROS) and inhibition of necroptosis in RGCs has become one of treatment strategies for glaucoma. However, existing drugs without efficient drug enter into the retina and have controlled release due to a short drug retention. Herein, we designed a glaucomatous microenvironment-responsive drug carrier polymer, which is characterized by the presence of thioketal bonds and 1,4-dithiane unit in the main chain for depleting ROS as well as the pendant cholesterols for targeting cell membranes. This polymer was adopted to encapsulate an inhibitor of necroptosis, necrostatin-1, into nanoparticles (designated as NP1). NP1 with superior biosafety could scavenge ROS in RGCs both in vitro and in vivo of an acute pathological glaucomatous injury model. Further, NP1 was found to effectively inhibit the upregulation of the necroptosis pathway, reducing the death of RGCs. The findings in this study exemplified the use of nanomaterials as potential strategies to treat glaucoma.

[Sidaxue, a traditional Guizhou Miao herbal medicine formula, reduces necroptosis and synovial vascular proliferation in rats with collagen-induced arthritis by inhibiting the RIPK1/RIPK3/MLKL pathway]

OBJECTIVE

To explore the inhibitory effect of Sidaxue (SX), a traditional Guizhou Miao herbal medicine formula, on necrotic apoptosis and synovial angiogenesis in rats with collagen-induced arthritis (CIA) and the role of the RIPK1/RIPK3/MLKL pathway in mediating this effect.

METHODS

Forty-two SD rats were randomized into 6 groups (n=7), including a normal control group, a CIA model group, 3 SX treatment groups at low (10 g/kg), moderate (20 g/kg) and high (40 g/kg) doses, and a GTW treatment group. CIA rat models were established by subcutaneous injections of bovine type II collagen, and the treatments were administered daily by gavage for 21 days. The rats were observed for swelling of the hind limb joints, which was rated using the arthritis index (AI) score on a weekly basis. Serum levels of TNF-α, IL-1β and IL-17 in the rats were detected using ELISA, and the pathological changes in the synovium were observed with HE staining. Real-time PCR was performed to detect the mRNA expression levels of VEGF, MMP-9, Ang-1, RIPK1, RIPK3, and caspase-8 in the synovial tissues, and the protein expressions of VEGF, MMP9, Ang-1, Stat-3, RIPK1, RIPK3, MLKLl, p-MLKL and caspase-8 were detected using Western blotting.

RESULTS

Compared with those in CIA model group, the rats receiving treatment with GTW and SX showed milder swelling of the hind limb joints with significantly lower AI scores (P < 0.05). In CIA model group, a large number of inflammatory cells were observed in the synovium with obvious damages of the tissue structure. In the drug treatment groups, inflammatory cell infiltration, synovial angiogenesis and synovial hyperplasia were alleviated, and the therapeutic effects were obviously enhanced as SX dose increased. Compared with those in the model group, the rats treated with GTW and high-dose SX showed significantly decreased serum levels of IL-1β, IL-17 and TNF-α (P < 0.05), lower mRNA and protein expressions of RIPK1, RIPK3, VEGF, Ang-1, and MMP9 (P < 0.05), higher expressions of caspase-8 (P < 0.01), and obviously lowered expression of Stat-3 protein and phosphorylation level of MLKL (P < 0.05).

CONCLUSION

SX can improve synovial angiogenesis in CIA rats possibly by inhibiting the activation of RIP1/RIP3/MLKL signaling pathway and down-regulating the expression of the vascular growth factors VEGF, Ang-1, MMP9, and Stat-3.

Necroptosis pathways in tumorigenesis

Necroptosis is a caspase-independent form of programmed cell death executed by the receptor interacting protein kinase 1 (RIPK1)-RIPK3-mixed lineage kinase domain-like protein (MLKL) signaling cascade, deregulation of which can cause various human diseases including cancer. Escape from programmed cell death is a hallmark of cancer, leading to uncontrolled growth and drug resistance. Therefore, it is crucial to further understand whether necroptosis plays a key role in therapeutic resistance. In this review, we summarize the recent findings of the link between necroptosis and cancer, and discuss that targeting necroptosis is a new strategy to overcome apoptosis resistance in tumor therapy.

Development of necroptosis-related gene signature to predict the prognosis of colon adenocarcinoma

Colon adenocarcinoma (COAD) is a common malignancy and has a high mortality rate. However, the current tumor node metastasis (TNM) staging system is inadequate for prognostic assessment of COAD patients. Therefore, there is an urgent need to identify reliable biomarkers for the prognosis COAD patients. The aberrant expression of necroptosis-related genes (NRGs) is reported to be associated with tumorigenesis and metastasis. In the present work, we compared the expression profiles of NRGs between COAD patients and normal individuals. Based on seven differentially expressed NRGs, a risk score was defined to predict the prognosis of COAD patients. The validation results from both training and independent external cohorts demonstrated that the risk score is able to distinguish the high and low risk COAD patients with higher accuracies, and is independent of the other clinical factors. To facilitate its clinical use, by integrating the proposed risk score, a nomogram was built to predict the risk of individual COAD patients. The C-index of the nomogram is 0.75, indicating the reliability of the nomogram in predicting survival rates. Furthermore, two candidate drugs, namely dapsone and xanthohumol, were screed out and validated by molecular docking, which hold the potential for the treatment of COAD. These results will provide novel clues for the diagnosis and treatment of COAD.

Analysis and identification of the necroptosis landscape on therapy and prognosis in bladder cancer

Bladder cancer (BLCA) is one of the most common malignant tumors of the urinary system, but the current therapeutic strategy based on chemotherapy and immune checkpoint inhibitor (ICI) therapy cannot meet the treatment needs, mainly owing to the endogenous or acquired apoptotic resistance of cancer cells. Targeting necroptosis provides a novel strategy for chemotherapy and targeted drugs and improves the efficacy of ICIs because of strong immunogenicity of necroptosis. Therefore, we systemically analyzed the necroptosis landscape on therapy and prognosis in BLCA. We first divided BLCA patients from The Cancer Genome Atlas (TCGA) database into two necroptosis-related clusters (C1 and C2). Necroptosis C2 showed a significantly better prognosis than C1, and the differential genes of C2 and C1 were mainly related to the immune response according to GO and KEGG analyses. Next, we constructed a novel necroptosis-related gene (NRG) signature consisting of SIRT6, FASN, GNLY, FNDC4, SRC, ANXA1, AIM2, and IKBKB to predict the survival of TCGA-BLCA cohort, and the accuracy of the NRG score was also verified by external datasets. In addition, a nomogram combining NRG score and several clinicopathological features was established to more accurately and conveniently predict the BLCA patient’s survival. We also found that the NRG score was significantly related to the infiltration levels of CD8 T cells, NK cells, and iDC cells, the gene expression of CTLA4, PD-1, TIGIT, and LAG3 of TME, and the sensitivity to chemotherapy and targeted agents in BLCA patients. In conclusion, the NRG score has an excellent performance in evaluating the prognosis, clinicopathologic features, tumor microenvironment (TME), and therapeutic sensitivity of BLCA patients, which could be utilized as a guide for chemotherapy, ICI therapy, and combination therapy.

A prognosis model for clear cell renal cell carcinoma based on four necroptosis-related genes

Necroptosis is a type of caspase-independent cell death, and it plays a critical role in regulating the development of cancer. To date, little is known about the role of necroptosis-related genes (NRGs) in clear cell renal cell carcinoma (ccRCC). In this study, we downloaded data regarding the expression of NRGs and overall survival (OS) from The Cancer Genome Atlas (TCGA) database and constructed a risk model to determine the prognostic features of necroptosis using COX regression analysis. Patients with ccRCC were divided into low-risk and high-risk groups based on their risk scores. Thereafter, Kaplan–Meier curves were used to evaluate OS, and receiver operating characteristic (ROC) curves were used to determine the accuracy of prediction. Stratified analyses were performed according to different clinical variables. Furthermore, we assessed the correlation between clinical variables and risk scores; the NRGs with differential expression were mainly enriched in positive regulation of intracellular transport and platinum resistance pathways. We constructed prognostic signatures for OS based on four NRGs and showed that the survival time was significantly longer in the low-risk groups than in the high-risk groups (p < 0.001). The area of the ROC curve for OS was 0.717, indicating excellent predictive accuracy of the established model. Therefore, a predictive model based on NRGs was constructed, which can predict the prognosis of patients and provides insights into the biological mechanisms underlying necroptosis in patients with ccRCC.

Benzo[a]pyrene exposure promotes RIP1-mediated necroptotic death of osteocytes and the JNK/IL-18 pathway activation via generation of reactive oxygen species

Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon (PAH) of environmental pollutants, readily produced during the processing of petroleum and fatty foods. BaP exposure can cause skeletal deformities. However, whether BaP affects osteocytes, making up over 95% of all the bone cells, remains unknown. This study aimed to investigate the effect of BaP on osteocytes in vivo and in vitro, as well as explore the underlying mechanisms. The in vivo data showed that BaP (50mg/kg) exposure for 12 weeks could cause bone destruction, and increase osteocytes death in mouse cortical femur. Our in vitro results revealed that BaP (25-100 μmol/L) exposure inhibited cell viability of MLO-Y4 cells, and resulted in cell death in a dose-dependent manner. Furthermore, BaP exposure significantly triggered necroptosis of MLO-Y4 cells, as indicated by increased propidium iodide (PI)-positive cells and up-regulation of necroptosis-related protein expressions of receptor-interacting protein kinase 1 (RIP1), RIP3, and mixed lineage kinase domain-like protein (MLKL). This necrotic effect was reversed by the RIP1 inhibitor necrostatin-1 (Nec-1). Simultaneously, BaP activated the downstream c-Jun N-terminal kinase (JNK)/ interleukin (IL)-18 signaling pathway, which was suppressed after the JNK inhibitor SP600125 or Nec-1 treatment. In addition, BaP exposure promoted the production of intracellular reactive oxygen species (ROS), mitochondrial ROS (mtROS), and elevated malondialdehyde (MDA) levels; while BaP decreased superoxide dismutase (SOD) activity and antioxidant enzymes including nuclear factor E₂-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) levels, leading to oxidative damage. The ROS scavenger N-acetylcysteine (NAC) inhibited this necroptotic death and the JNK/IL-18 pathway activation. Collectively, BaP exposure may cause RIP1-mediated necroptotic death of osteocytes and activate the JNK/IL-18 pathway via ROS generation.

Characterization of Necroptosis-Related Molecular Subtypes and Therapeutic Response in Lung Adenocarcinoma

Lung adenocarcinoma (LUAD) is one of the most common malignant tumors with high morbidity and mortality and is usually associated with therapeutic resistance and poor prognosis because of individual biological heterogeneity. There is an unmet need to screen for reliable parameters, especially immunotherapy-related biomarkers to predict the patient’s outcomes. Necroptosis is a special caspase-independent form of necrotic cell death associated with the pathogenesis, progression, and prognosis of multiple tumors but the potential connection between necroptosis-related genes (NRGs) and LUAD still remains unclear. In this study, we expounded mutational and transcriptional alterations of 67 NRGs in 522 LUAD samples and proposed a consensus-clustering subtype of these patients into two cohorts with distinct immunological and clinical prognosis characteristics. Cluster B patients were associated with a better prognosis and characterized by relatively lower expression of NRGs, higher immune scores in the tumor microenvironment (TME), more mild clinical stages, and downregulated expression of immunotherapy checkpoints. Subsequently, the NRG score was further established to predict the overall survival (OS) of LUAD patients using univariate Cox, LASSO, and multivariate Cox regression analyses. The immunological characteristics and potential predictive capability of NRG scores were further validated by 583 LUAD patients in external datasets. In addition to better survival and immune-activated conditions, low-NRG-score cohorts exhibited a significant positive correlation with the mRNA stem index (mRNAsi) and tumor mutation burden (TMB) levels. Combined with classical clinical characteristics and NRG scores, we successfully defined a novel necroptosis-related nomogram to accurately predict the 1/3/5-year survival rate of individual LUAD patients, and the potential predictive capability was further estimated and validated in multiple test datasets with high AUC values. Integrated transcriptomic analysis helps us seek vital NRGs and supplements a novel clinical application of NRG scores in predicting the overall survival and therapeutic benefits for LUAD patients.

Necroptosis-Related Genes Associated With Immune Activity and Prognosis of Colorectal Cancer

This study aims at screening out the key necroptosis-related genes in colorectal cancer and elucidating the role of necroptosis-related genes in the immune activity and prognosis of colorectal cancer (CRC). The CRC patients’ data were downloaded from The Cancer Genome Atlas (TCGA). The non-negative matrix factorization method was applied to identify new molecular subgroups. Survival analysis and single sample Gene Set Enrichment Analysis were performed to determinate the differences in the overall survival time and immune status of the subgroups. Prognostic model was constructed on the basis of univariate Cox regression and LASSO analysis. Functional analyses were used to explore the potential mechanisms. Based on prognostic related necroptosis genes, we identify two molecular subgroups with significantly different survival. The better prognosis was associated with more active immune infiltration and upregulated expression of immune checkpoints. We screened nine necroptosis related genes as key prognostic genes and established a risk model, which showed a good potential for survival prediction in colorectal cancer. Nomogram assessment showed that the model had high reliability for predicting the prognosis of colorectal cancer patients. The high-risk and low-risk group also has different sensitivity to immunotherapy and commonly used drugs for colorectal cancer. Overall, necroptosis related genes were involved in the immune microenvironment of colorectal cancer patient, could be utilized to predict the prognosis of colorectal cancer and develop more individualized treatment.

Understanding Necroptosis in Pancreatic Diseases

Intermediate between apoptosis and necrosis, necroptosis is a regulated caspase-independent programmed cell death that induces an inflammatory response and mediates cancer development. As our understanding improves, its role in the physiopathology of numerous diseases, including pancreatic diseases, has been reconsidered, and especially in pancreatitis and pancreatic cancer. However, the exact pathogenesis remains elusive, even though some studies have been conducted on these diseases. Its unique mechanisms of action in diseases are expected to bring prospects for the treatment of pancreatic diseases. Therefore, it is imperative to further explore its molecular mechanism in pancreatic diseases in order to identify novel therapeutic options. This article introduces recent related research on necroptosis and pancreatic diseases, explores necroptosis-related molecular pathways, and provides a theoretical foundation for new therapeutic targets for pancreatic diseases.

Identification and Quantification of Necroptosis Landscape on Therapy and Prognosis in Kidney Renal Clear Cell Carcinoma

Kidney renal clear cell carcinoma (KIRC) has high morbidity and gradually increased in recent years, and the rate of progression once relapsed is high. At present, owing to lack of effective prognosis predicted markers and post-recurrence drug selection guidelines, the prognosis of KIRC patients is greatly affected. Necroptosis is a regulated form of cell necrosis in a way that is independent of caspase. Induced necroptosis is considered an effective strategy in chemotherapy and targeted drugs, and it can also be used to improve the efficacy of immunotherapy. Herein, we quantified the necroptosis landscape of KIRC patients from The Cancer Genome Atlas (TCGA) database and divided them into two distinct necroptosis-related patterns (C1 and C2) through the non-negative matrix factorization (NMF) algorithm. Multi-analysis revealed the differences in clinicopathological characteristics and tumor immune microenvironment (TIME). Then, we constructed the NRG prognosis signature (NRGscore), which contained 10 NRGs (PLK1, APP, TNFRSF21, CXCL8, MYCN, TNFRSF1A, TRAF2, HSP90AA1, STUB1, and FLT3). We confirmed that NRGscore could be used as an independent prognostic marker for KIRC patients and performed excellent stability and accuracy. A nomogram model was also established to provide a more beneficial prognostic indicator for the clinic. We found that NRGscore was significantly correlated with clinicopathological characteristics, TIME, and tumor mutation burden (TMB) of KIRC patients. Moreover, NRGscore had effective guiding significance for immunotherapy, chemotherapy, and targeted drugs.

Stereotactic body radiation combined with oncolytic vaccinia virus induces potent anti-tumor effect by triggering tumor cell necroptosis and DAMPs

Radiation is an integral part of cancer therapy. With the emergence of oncolytic vaccinia virus immunotherapy, it is important to study the combination of radiation and vaccinia virus in cancer therapy. In this study, we investigated the anti-tumor effect of and immune mechanisms underlying the combination of high-dose hypofractionated stereotactic body radiotherapy (SBRT) and oncolytic vaccinia virus in preclinical murine models. The combination enhanced the in vivo anti-tumor effect and increased the numbers of splenic CD4⁺Ki-67⁺ helper T lymphocytes and CD8⁺Ki-67⁺ cytotoxic T lymphocytes. Combinational therapy also increased tumor-infiltrating CD3⁺CD4⁺ helper T lymphocytes and CD3⁺CD8⁺ cytotoxic T lymphocytes, but decreased tumor-infiltrating regulatory T cells. In addition, SBRT combined with oncolytic vaccinia virus enhanced in vitro cell death, partly through necroptosis, and subsequent release of damage-associated molecular patterns (DAMPs), and shifted the macrophage M1/M2 ratio. We concluded that SBRT combined with oncolytic vaccinia virus can trigger tumor cell necroptosis and modify macrophages through the release of DAMPs, and then generate potent anti-tumor immunity and effects. Thus, combined therapy is potentially an important strategy for clinical cancer therapy.

Roles of the CXCL8-CXCR1/2 Axis in the Tumor Microenvironment and Immunotherapy

In humans, Interleukin-8 (IL-8 or CXCL8) is a granulocytic chemokine with multiple roles within the tumor microenvironment (TME), such as recruiting immunosuppressive cells to the tumor, increasing tumor angiogenesis, and promoting epithelial-to-mesenchymal transition (EMT). All of these effects of CXCL8 on individual cell types can result in cascading alterations to the TME. The changes in the TME components such as the cancer-associated fibroblasts (CAFs), the immune cells, the extracellular matrix, the blood vessels, or the lymphatic vessels further influence tumor progression and therapeutic resistance. Emerging roles of the microbiome in tumorigenesis or tumor progression revealed the intricate interactions between inflammatory response, dysbiosis, metabolites, CXCL8, immune cells, and the TME. Studies have shown that CXCL8 directly contributes to TME remodeling, cancer plasticity, and the development of resistance to both chemotherapy and immunotherapy. Further, clinical data demonstrate that CXCL8 could be an easily measurable prognostic biomarker in patients receiving immune checkpoint inhibitors. The blockade of the CXCL8-CXCR1/2 axis alone or in combination with other immunotherapy will be a promising strategy to improve antitumor efficacy. Herein, we review recent advances focusing on identifying the mechanisms between TME components and the CXCL8-CXCR1/2 axis for novel immunotherapy strategies.

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.

Tumor necroptosis is correlated with a favorable immune cell signature and programmed death-ligand 1 expression in cholangiocarcinoma

Necroptosis, a regulated form of necrosis, has emerged as a novel therapeutic strategy that could enhance cancer immunotherapy. However, its role in tumorigenesis is still debated because recent studies have reported both anti- and pro-tumoral effects. Here, we aimed to systematically evaluate the associations between tumor necroptosis (mixed lineage kinase domain-like protein, MLKL; phosphorylated MLKL, pMLKL; and receptor-interacting protein kinase 1-receptor-interacting protein kinase 3, RIPK1-RIPK3 interaction) and tumor-infiltrating immune cells (CD8+ and FOXp3+ T cells and CD163+ M2 macrophages) and tumor PD-L1 by immunohistochemistry in 88 cholangiocarcinoma (CCA) patients who had undergone surgical resection. Their associations with clinicopathological characteristics, survival data, and prognosis were evaluated. MLKL was found to be an unfavorable prognostic factor (p-value = 0.023, HR = 2.070) and was inversely correlated with a clinically favorable immune cell signature (high CD8+/high FOXp3+/low CD163+). Both pMLKL and RIPK1-RIPK3 interaction were detected in CCA primary tissues. In contrast to MLKL, pMLKL status was significantly positively correlated with a favorable immune signature (high CD8+/high FOXp3+/low CD163+) and PD-L1 expression. Patients with high pMLKL-positive staining were significantly associated with an increased abundance of CD8+ T cell intratumoral infiltration (p-value = 0.006). Patients with high pMLKL and PD-L1 expressions had a longer overall survival (OS). The results from in vitro experiments showed that necroptosis activation in an RMCCA-1 human CCA cell line selectively promoted proinflammatory cytokine and chemokine expression. Jurkat T cells stimulated with necroptotic RMCCA-1-derived conditioned medium promoted PD-L1 expression in RMCCA-1. Our findings demonstrated the differential associations of necroptosis activation (pMLKL) and MLKL with a clinically favorable immune signature and survival rates and highlighted a novel therapeutic possibility for combining a necroptosis-based therapeutic approach with immune checkpoint inhibitors for more efficient treatment of CCA patients.

Nrf2 alleviates radiation-induced rectal injury by inhibiting of necroptosis

Radiation-induced rectal injury is one of the common side effects of pelvic radiation therapy. This study aimed to explore the role of nuclear factor erythroid 2-related factor 2 (Nrf2) in this process. In vivo, knockout (KO) of Nrf2 led to aggravated radiation-induced histological changes in the rectums. In vitro, interference or overexpression of Nrf2 resulted in enhanced or reduced radiosensitivity in human intestinal epithelial crypts (HIEC) cells, respectively. A potential relationship between Nrf2 and necroptosis was identified using RNA sequencing (RNA-seq) and western blotting (WB), which showed that necroptosis-related proteins were negatively correlated with Nrf2. Upon treatment with necrostatin-1 (Nec-1), the increased radiosensitivity, decreased cell viability, increased γH2AX foci formation, and decreased mitochondrial membrane potential (MMP) in Nrf2-interfered HIEC cells were alleviated. A significant recovery in morphological alterations was also observed in Nrf2 KO mice administered with Nec-1. Taken together, our results highlight the important protective effect of Nrf2 in radiation-induced rectal injury through the inhibition of necroptosis, and the physiological significance of necroptosis in radiation-induced rectal injury.

TNF-α Triggers RIP1/FADD/Caspase-8-Mediated Apoptosis of Astrocytes and RIP3/MLKL-Mediated Necroptosis of Neurons Induced by Angiostrongylus cantonensis Infection

Angiostrongylus cantonensis (AC) can cause severe eosinophilic meningitis or encephalitis in non-permissive hosts accompanied by apoptosis and necroptosis of brain cells. However, the explicit underlying molecular basis of apoptosis and necroptosis upon AC infection has not yet been elucidated. To determine the specific pathways of apoptosis and necroptosis upon AC infection, gene set enrichment analysis (GSEA) and protein-protein interaction (PPI) analysis for gene expression microarray (accession number: GSE159486) of mouse brain infected by AC revealed that TNF-α likely played a central role in the apoptosis and necroptosis in the context of AC infection, which was further confirmed via an in vivo rescue assay after treating with TNF-α inhibitor. The signalling axes involved in apoptosis and necroptosis were investigated via immunoprecipitation and immunoblotting. Immunofluorescence was used to identify the specific cells that underwent apoptosis or necroptosis. The results showed that TNF-α induced apoptosis of astrocytes through the RIP1/FADD/Caspase-8 axis and induced necroptosis of neurons by the RIP3/MLKL signalling pathway. In addition, in vitro assay revealed that TNF-α secretion by microglia increased upon LSA stimulation and caused necroptosis of neurons. The present study provided the first evidence that TNF-α was secreted by microglia stimulated by AC infection, which caused cell death via parallel pathways of astrocyte apoptosis (mediated by the RIP1/FADD/caspase-8 axis) and neuron necroptosis (driven by the RIP3/MLKL complex). Our research comprehensively elucidated the mechanism of cell death after AC infection and provided new insight into targeting TNF-α signalling as a therapeutic strategy for CNS injury.

5-((7-Chloro-6-fluoro-1h-indol-3-yl) methyl)-3-methylimidazolidine-2,4-dione as a RIP1 inhibitor protects LPS/D-galactosamine-induced liver failure

AIMS

Necroptosis, an inflammatory form of regulated necrosis mediated by receptor-interacting kinase 1 (RIP1), RIP3, and pseudokinase mixed lineage kinase domain-like protein (MLKL) is extensively implicated in liver inflammatory disease. Thus identification small-molecule inhibitor of necroptosis has emerged as a potential therapeutic strategy to prevent liver damage. In this study, we identified 5-((7-chloro-6-fluoro-1 h-indol-3-yl) methyl)-3-methylimidazolidine-2,4-dione (F-nec) as a novel potent necroptosis inhibitor.

MAIN METHODS

To find out the potent chemical inhibitors of necroptosis, human monocytic U937 cells were treated with a combination of tumor necrosis factor alpha (TNFα) and a pan-caspase inhibitor z-VAD-fmk. LPS and D-galactosamine (LPS/GalN) were further employed to simulate acute liver failure to explore therapeutic potency of F-nec in vivo. In addition, a specific inhibitor of c-Jun NH (2)-terminal kinases (JNK) SP600125 and its activator anisomycin are used to elucidate its mechanisms in acute liver failure therapy. Necroptosis pathway related proteins were tested by western blot.

KEY FINDINGS

In this study, we identified F-nec as a novel potent RIP1 inhibitor which efficiently blocked TNFα-induced necroptosis in human and mice cells. Furthermore, pre-treatment of F-nec could prevent hepatic necrosis by reducing RIP1-mediated necroptosis also effectively ameliorated LPS/GalN induced acute liver failure by attenuating cell death signaling-stimulated JNK pathway activation and then suppressing JNK-triggered inflammation.

SIGNIFICANCE

Altogether, this study demonstrates that F-nec is a potent inhibitor of RIP1 and highlights its great potential for use in the treatment of RIP1-driven inflammatory liver diseases.

A narrative review of the role of necroptosis in liver disease: a double-edged sword

Acute and chronic liver injuries lead to hepatocyte death and turnover. When injuries become chronic, continuous cell death and transformation lead to chronic inflammation, fibrosis, cirrhosis, and eventually carcinoma. A therapeutic strategy of great significance for liver disease is to control hepatocyte death in acute and chronic injuries. This strategy prevents hepatocytes from causing liver failure and inhibits both secondary inflammation and fibrosis. Both apoptosis and necrosis have been proven to occur in the liver, but the role of necroptosis in liver diseases is controversial. Necroptosis, which has features of necrosis and apoptosis, is a regulatory process that occurs in some cell types when caspases are inhibited. The signaling pathway of necroptosis is characterized by the activation of receptor-interacting proteins kinase (RIPK) and mixed lineage kinase domain-like (MLKL). Necroptosis is associated with a variety of inflammatory diseases and has been the focus of research in recent years. The incidence of necroptosis in liver tissues has been studied recently in several liver injury models, but the results of the studies are not consistent. The purpose of this review is to summarize the published data on the involvement of necroptosis in liver injury, focusing on the controversies, issues remaining to be discussed, and potential therapeutic applications in this area.

Compensatory combination of mTOR and TrxR inhibitors to cause oxidative stress and regression of tumors

Background: Cancer is a leading cause of death worldwide. Extensive research over decades has led to the development of therapies that inhibit oncogenic signaling pathways. The mammalian target of rapamycin (mTOR) signaling pathway plays an important role in the development of many cancers. Several mTOR inhibitors are approved for the treatment of cancers. However, the anticancer efficacies of mTOR inhibitor monotherapy are still limited.

Methods: Western blot was used to detect the expression of indicated molecules. Thioredoxin reductase (TrxR) activity in cells was determined by the endpoint insulin reduction assay. Immunofluorescence staining was used to analyze precise location and expression of target proteins. Nude mice were used for xenograft tumor models.

Results: We identified a synergistic lethal interaction of mTOR and TrxR inhibitors and elucidated the underlying molecular mechanisms of this synergism. We demonstrated that mTOR and TrxR inhibitors cooperated to induce cell death by triggering oxidative stress, which led to activation of autophagy, endoplasmic reticulum (ER) stress and c-Jun N-terminal Kinase (JNK) signaling pathway in cancer cells. Remarkably, we found that auranofin (AF) combined with everolimus significantly suppressed tumor growth in HCT116 and SGC-7901 xenograft models with no significant signs of toxicity.

Conclusion: Our findings identify a promising therapeutic combination for cancer and has important implications for developing mTOR inhibitor-based combination treatments.

Role of apoptosis repressor with caspase recruitment domain (ARC) in cell death and cardiovascular disease

Apoptosis repressor with caspase recruitment domain (ARC) is a highly effective and multifunctional inhibitor of apoptosis that is mainly expressed in postmitotic cells such as cardiomyocytes and skeletal muscle cells. ARC contains a C-terminal region rich in proline and glutamic acid residues and an N-terminal caspase recruitment domain (CARD). The CARD is originally described as a protein-binding motif that interacts with caspase through a CARD-CARD interaction. Initially, the inhibitory effect of ARC was only found in apoptosis, however, it was later found that ARC also played a regulatory role in other types of cell death. As a powerful cardioprotective factor, ARC can protect the heart by inhibiting the death of cardiomyocytes in various ways. ARC can reduce the cardiomyocyte apoptotic response to various stresses and injuries, including extrinsic apoptosis induced by death receptor ligands, cellular Ca²⁺ homeostasis and the dysregulation of endoplasmic reticulum (ER) stress, oxidative stress and hypoxia. In addition, changes in ARC transcription and translation levels in the heart can cause a series of physiological and pathological changes, and ARC can also perform corresponding functions through interactions with other molecules. Although there has been much research on ARC, the functional redundancy among proteins shows that ARC still has much research value. This review summarizes the molecular characteristics of ARC, its roles in the various death modes in cardiomyocytes and the roles of ARC in cardiac pathophysiology. This article also describes the potential therapeutic effect and research prospects of ARC.

Prediction of Clinical Outcome in Locally Advanced Non-Small Cell Lung Cancer Patients Treated With Chemoradiotherapy by Plasma Markers

Purpose

To identify cytokines in plasma that may predict objective response and progression-free survival (PFS) in patients with locally advanced non-small cell lung cancer (NSCLC) treated with chemoradiotherapy.

Materials and Methods

From April 2016 to May 2017, thirty-one patients with locally advanced inoperable/unresectable NSCLC were included, and treated with concurrent chemoradiotherapy (CCRT). No immune checkpoint inhibitors were administered after CCRT. Plasma from each patient was collected before radiotherapy, and 25 cytokines in the plasma were measured by Luminex or U-PLEX assays. Logistic regression and COX regression were performed to identify the predictive factors for objective response and PFS, respectively. Kaplan-Meier survival analysis was used to compare the PFS between the groups.

Results

High levels of IL-13 and TNF-α, and low levels of ICAM-1, IFN-γ, and soluble PD-L1 (sPD-L1) were significantly associated with objective response (P <0.05). High levels of IL-8, CCL5, and CXCL3 also showed a trend toward association with objective response (P <0.1). The combination of cytokines (IL-8 and ICAM-1, or TNF-α and sPD-L1) improved predictive accuracy. Univariate analysis identified IL-8 and ICAM-1 as potential markers to predict PFS. Multivariate analysis suggested that high level of IL-8 (P =0.010) and low level of ICAM-1 (P =0.011) correlated significantly with a longer PFS.

Conclusion

IL-8 and ICAM-1 in plasma have the potential to predict objective response and PFS in patients with locally advanced NSCLC underwent chemoradiotherapy.