Pyroptosis in combinatorial treatment to improve cancer patients' outcome, is that what we want?

Crosstalk between hypoxia-induced pyroptosis and immune escape in cancer: From mechanisms to therapy

Pyroptosis can be triggered through both canonical and non-canonical inflammasome pathways, involving the cleavage of gasdermin (GSDM) protein family members, like GSDMD and GSDME. The impact of pyroptosis on tumors is nuanced, because its role in regulating cancer progression and anti-tumor immunity may vary depending on the tumor type, stage, location, and immune status. However, pyroptosis cannot be simply categorized as promoting or inhibiting tumors based solely on whether it is acute or chronic in nature. The interplay between pyroptosis and cancer is intricate, with some evidence suggesting that chronic pyroptosis may facilitate tumor growth, while the acute induction of pyroptosis could stimulate anti-cancer immune responses. Tumor hypoxia activates hypoxia inducible factor (HIF) signaling to modulate pyroptosis and immune checkpoint expression. Targeting this hypoxia-pyroptosis-immune escape axis could be a promising therapeutic strategy. This review highlights the complex crosstalk between hypoxia, pyroptosis, and immune evasion in the TME.

Penehyclidine hydrochloride alleviates lung ischemia-reperfusion injury by inhibiting pyroptosis

OBJECTIVE

The aim of this research was to examine how penehyclidine hydrochloride (PHC) impacts the occurrence of pyroptosis in lung tissue cells within a rat model of lung ischemia-reperfusion injury.

METHODS

Twenty-four Sprague Dawley (SD) rats, weighing 250 g to 270 g, were randomly distributed into three distinct groups as outlined below: a sham operation group (S group), a control group (C group), and a test group (PHC group). Rats in the PHC group received a preliminary intravenous injection of PHC at a dose of 3 mg/kg. At the conclusion of the experiment, lung tissue and blood samples were collected and properly stored for subsequent analysis. The levels of malondialdehyde, superoxide dismutase, and myeloperoxidase in the lung tissue, as well as IL-18 and IL-1β in the blood serum, were assessed using an Elisa kit. Pyroptosis-related proteins, including Caspase1 p20, GSDMD-N, and NLRP3, were detected through the western blot method. Additionally, the dry-to-wet ratio (D/W) of the lung tissue and the findings from the blood gas analysis were also documented.

RESULTS

In contrast to the control group, the PHC group showed enhancements in oxygenation metrics, reductions in oxidative stress and inflammatory reactions, and a decrease in lung injury. Additionally, the PHC group exhibited lowered levels of pyroptosis-associated proteins, including the N-terminal segment of gasdermin D (GSDMD-N), caspase-1p20, and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3).

CONCLUSION

Pre-administration of PHC has the potential to mitigate lung ischemia-reperfusion injuries by suppressing the pyroptosis of lung tissue cells, diminishing inflammatory reactions, and enhancing lung function. The primary mechanism behind anti-pyroptotic effect of PHC appears to involve the inhibition of oxidative stress.

Quercetin-induced pyroptosis in colon cancer through NEK7-mediated NLRP3 inflammasome-GSDMD signaling pathway activation

Pyroptosis, a gasdermin-mediated lytic cell death, is a new hotspot topic in cancer research, and induction of tumor pyroptosis has emerged as a new target in cancer management. Quercetin (Que), a natural substance, demonstrates promising anticancer action. However, further information is required to fully comprehend the function and mechanism of Que in pyroptosis in colon cancer. This study revealed the underlying mechanism of Que-induced pyroptosis in colon cancer in vitro and in vivo. Que inhibited colon cancer cell growth through gasdermin D (GSDMD)-mediated pyroptosis. Depletion of GSDMD, rather than gasdermin E (GSDME), reversed the cytotoxic effects of Que on colon cancer cells. Que treatment upregulated NIMA-related kinase 7 (NEK7) protein expression, thus facilitating the assembly of the NLRP3 inflammasome and cleavage of GSDMD. NEK7 silencing resulted in colon cancer cell growth in vitro and in vivo. Mechanistically, NEK7 depression restrained the activation of the NLRP3 inflammasome-GSDMD pathway, thus attenuating pyroptosis triggered by Que in colon cancer cells. Furthermore, lower NEK7 and NLRP3 expression levels indicated colon cancer progression. Our results unveiled a novel pattern of anti-colon cancer activity of Que, and activation of NEK7-mediated pyroptosis is potentially a promising therapeutic target for colon cancer, which provides novel experimental proof for the clinical application of Que.

When pyro(ptosis) meets palm(itoylation)

Pyroptosis, a programmed cell death process, is vital for the immune response against microbial infections and internal danger signals. Recent studies have highlighted the importance of protein palmitoylation, a modification that involves attaching palmitate to cysteine residues, in regulating key proteins involved in pyroptosis. Palmitoylation of cGAS at residue C474 by ZDHHC18 affects its enzymatic activity and DNA binding ability. Similarly, ZDHHC9 promotes cGAS activity through palmitoylation at residues C404/405. NLRP3 palmitoylation at residue C844, mediated by ZDHHC12, impacts its stability and interactions with other proteins, crucial for activating the NLRP3 inflammasome and triggering inflammation. However, the role of ZDHHC5 in NLRP3 palmitoylation remains uncertain due to conflicting findings. Palmitoylation at C88/91 is essential for STING activation and induction of type I interferons. It modulates the formation of multimeric complexes and downstream signaling pathways. GSDMD palmitoylation at C191 is necessary for pore formation and membrane translocation, while GSDME palmitoylation at C407/408 is associated with drug-induced pyroptosis. Moreover, palmitoylation of NOD1 and NOD2 influences their membrane recruitment and immune signaling pathways in response to bacterial peptidoglycans, acting as upstream regulators of pyroptosis. This review summarizes the important roles for palmitoylation in regulating the function of key pyroptosis-related proteins, shedding light on the intricate mechanisms governing immune responses and inflammation.

Obstructive Sleep Apnea Plasma-Derived Exosomes Mediate Cognitive Impairment Through Hippocampal Neuronal Cell Pyroptosis

OBJECTIVE

Obstructive sleep apnea (OSA) is associated with impaired cognitive function. Exosomes are secreted by most cells and play a role in OSA-associated cognitive impairment (CI). The aim of this study was to investigate whether OSA plasma-derived exosomes cause CI through hippocampal neuronal cell pyroptosis, and to identify exosomal miRNAs in OSA plasma-derived.

MATERIALS AND METHODS

Plasma-derived exosomes were isolated from patients with severe OSA and healthy comparisons. Daytime sleepiness and cognitive function were assessed using the Epworth Sleepiness Scale (ESS) and the Beijing version of the Montreal Cognitive Assessment Scale (MoCA). Exosomes were coincubated with mouse hippocampal neurons (HT22) cells to evaluate the effect of exosomes on pyroptosis and inflammation of HT22 cells. Meanwhile, exosomes were injected into C57BL/6 male mice via caudal vein, and then morris water maze was used to evaluate the spatial learning and memory ability of the mice, so as to observe the effects of exosomes on the cognitive function of the mice. Western blot and qRT-PCR were used to detect the expressions of Gasdermin D (GSDMD) and Caspase-1 to evaluate the pyroptosis level. The expression of IL-1β, IL-6, IL-18 and TNF-α was detected by qRT-PCR to assess the level of inflammation. Correlations of GSDMD and Caspase-1 expression with clinical parameters were evaluated using Spearman's rank correlation analysis. In addition, plasma exosome miRNAs profile was identified, followed by Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways.

RESULTS

Compared to healthy comparisons, body mass index (BMI), apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and ESS scores were increased in patients with severe OSA, while lowest oxygen saturation during sleep (LSaO2), mean oxygen saturation during sleep (MSaO2) and MoCA scores were decreased. Compared to the PBS group (NC) and the healthy comparison plasma-derived exosomes (NC-EXOS), the levels of GSDMD and Caspase-1 and IL-1β, IL-6, IL-18 and TNF-α were increased significantly in the severe OSA plasma-derived exosomes (OSA-EXOS) coincubated with HT22 cells. Compared to the NC and NC-EXOS groups, the learning and memory ability of mice injected with OSA-EXOS was decreased, and the expression of GSDMD and Caspase-1 in hippocampus were significantly increased, along with the levels of IL-1β, IL-6, IL-18 and TNF-α. Spearman correlation analysis found that clinical AHI in HCs and severe OSA patients was positively correlated with GSDMD and Caspase-1 in HT22 cells from NC-EXOS and OSA-EXOS groups, while negatively correlated with clinical MoCA. At the same time, clinical MoCA in HCs and severe OSA patients was negatively correlated with GSDMD and Caspase-1 in HT22 cells from NC-EXOS and OSA-EXOS groups. A unique exosomal miRNAs profile was identified in OSA-EXOS group compared to the NC-EXOS group, in which 28 miRNAs were regulated and several KEGG and GO pathways were identified.

CONCLUSIONS

The results of this study show a hypothesis that plasma-derived exosomes from severe OSA patients promote pyroptosis and increased expression of inflammatory factors in vivo and in vitro, and lead to impaired cognitive function in mice, suggesting that OSA-EXOS can mediate CI through pyroptosis of hippocampal neurons. In addition, exosome cargo from OSA-EXOS showed a unique miRNAs profile compared to NC-EXOS, suggesting that plasma exosome associated miRNAs may reflect the differential profile of OSA related diseases, such as CI.

Caffeic acid phenethyl ester: A review on its pharmacological importance, and its association with free radicals, COVID-19, and radiotherapy

Caffeic acid phenethyl ester (CAPE), a main active component of propolis and a flavonoid, is one of the natural products that has attracted attention in recent years. CAPE, which has many properties such as anti-cancer, anti-inflammatory, antioxidant, antibacterial and anti-fungal, has shown many pharmacological potentials, including protective effects on multiple organs. Interestingly, molecular docking studies showed the possibility of binding of CAPE with replication enzyme. In addition, it was seen that in order to increase the binding security of the replication enzyme and CAPE, modifications can be made at three sites on the CAPE molecule, which leads to the possibility of the compound working more powerfully and usefully to prevent the proliferation of cancer cells and reduce its rate. Also, it was found that CAPE has an inhibitory effect against the main protease enzyme and may be effective in the treatment of SARS-CoV-2. This review covers in detail the importance of CAPE in alternative medicine, its pharmacological value, its potential as a cancer anti-proliferative agent, its dual role in radioprotection and radiosensitization, and its use against coronavirus disease 2019 (COVID-19).

PCSK9: A emerging participant in heart failure

Heart failure (HF) is a complex clinical syndrome caused by various cardiovascular diseases. Its main pathogenesis includes cardiomyocyte loss, myocardial energy metabolism disorder, and activation of cardiac inflammation. Due to the clinically unsatisfactory treatment of heart failure, different mechanisms need to be explored to provide new targets for the treatment of this disease. Proprotein convertase subtilisin/kexin type 9 (PCSK9), a gene mainly related to familial hypercholesterolemia, was discovered in 2003. Aside from regulating lipid metabolism, PCSK9 may be involved in other biological processes such as apoptosis, autophagy, pyroptosis, inflammation, and tumor immunity and related to diabetes and neurodegenerative diseases. Recently, clinical data have shown that the circulating PCSK9 level is significantly increased in patients with heart failure, and it is related to the prognosis for heart failure. Furthermore, in animal models and patients with myocardial infarction, PCSK9 in the infarct margin area was also found to be significantly increased, which further suggested that PCSK9 might be closely related to heart failure. However, the specific mechanism of how PCSK9 participates in heart failure remains to be further explored. The purpose of this review is to summarize the potential mechanism of PCSK9's involvement in heart failure, thereby providing a new treatment strategy for heart failure.

Pyroptosis relates to tumor microenvironment remodeling and prognosis: A pan-cancer perspective

Background and aim

Pyroptosis is an inflammatory form of programmed cell death implicated in inflammation and disease. Moreover, inducing pyroptosis has been appreciated as anti-cancer therapy for its ability to unleash anti-cancer immune responses.

Methods

Utilizing the data available in The Cancer Genome Atlas (TCGA), pyroptosis-related genes' (PRGs) expression, genomic aberrations, and clinical significance were systematically analyzed in pan-cancer. A GSVA score was obtained to rate pyroptosis level and divide the cancers into pyroptosis-low and pyroptosis-high groups. Immunohistochemistry (IHC) was used to evaluate the differential expression of major PRGs (GSDMC, GSDMD, GSDME, NLRP3, NLRC4, IL1B) in selected tumor types (COAD, HNSC, KIRC, LIHC, LUAD, LUSC). Selection of tumors for immunohistochemistry (IHC) was based on their expression pattern in TCGA cancers, clinical relevance, tumor epidemiology, and sample availability.

Results

Differential expression of PRGs was evident in various cancers and associated with prognosis which was driven by genomic variations and epigenetic abnormalities, such as single nucleotide variations (SNVs), copy number variation (CNV) and DNA methylation level. For example, methylation of PRGs in lower grade glioma (LGG), uveal melanoma (UVM) and kidney renal clear cell carcinoma (KIRC) were predictive of improved survival as upregulation of PRGs was risky in these cancers. Pyroptosis level significantly differentiated tumor from normal samples in 15 types of cancers, exhibited a progressive trend with cancer stage, observed variation among cancer subtypes, and showed a significant association with cancer prognosis. Higher pyroptosis level was associated with worst prognosis in majority of the cancers in terms of OS (KIRC, LGG, and UVM), PFS (GBM, KIRC, LGG, PRAD, THCA, and THYM) and DSS (KIRC and LGG) as estimated by Kaplan-Meier survival curves. Moreover, Pyroptosis level was strongly indicative of a hot tumor immune microenvironment with high presence of CD8+ T cell and other T cell subtypes. Several oncogenic pathways, such as P53 pathway, DNA repair, KRAS signaling, epithelial-mesenchymal transition (EMT), IL6 JAK STAT3 signaling, IL2 STAT5 signaling, PI3K AKT MTOR signaling and angiogenesis, were enriched in pyroptosis-hi subgroups across cancers.

Conclusions

Genetic alterations in PRGs greatly influence the pyroptosis level and cancer prognosis. A relatively hot tumor immune microenvironment was associated with pyroptosis irrespective of the cancer prognosis. Overall, our study reveals the critical role of pyroptosis in cancer and highlights pyroptosis-based therapeutic vulnerabilities.

LINC00511/hsa-miR-573 axis-mediated high expression of Gasdermin C associates with dismal prognosis and tumor immune infiltration of breast cancer

Breast cancer (BC) is considered the second commonest human carcinoma and the most incident and mortal in the female population. Despite promising treatments for breast cancer, mortality rates of metastatic disease remain high. Gasdermin C (GSDMC) is an affiliate of the gasdermin (GSDM) family, which is involved in the process of pyroptosis. Pyroptosis is implicated in tumorigenesis, but the role of GSDMC in cancer cells is yet to be fully elucidated. In this study, we investigated the role and mechanism of GSDMC in breast cancer. We conducted a pan-cancer analysis of the expression and prognosis of GSDMC utilizing multidimensional data from The Cancer Genome Atlas (TCGA). We investigated GSDMC expression levels in 15 BC tissues and matched adjacent normal tissues by immunohistochemistry (IHC). Further verification was performed in the Gene Expression Omnibus (GEO) database. We discovered that elevated GSDMC expression was considerably linked to a worse prognosis in breast invasive carcinoma (BRCA). Next, we identified noncoding RNAs (ncRNAs) which contributing to higher expression of GSDMC by a series of expression, survival, and correlation analysis. We finally identified LINC00511/hsa-miR-573 axis to be the most promising ncRNA-associated pathways that account for GSDMC in BRCA. Furthermore, we demonstrated the significant correlations between GSDMC expression and immune infiltrates, immune checkpoints, and immune markers in BRCA. This study illustrated that ncRNAs-mediated upregulation of GSDMC linked to dismal prognosis and also exhibited a correlation with tumor immune cell infiltration in BRCA. It is anticipated to offer novel ideas for the link between pyroptosis and tumor immunotherapy.

A Predictive Model Based on Pyroptosis-Related Gene Features Can Effectively Predict Clear Cell Renal Cell Carcinoma Prognosis and May Be an Underlying Target for Immunotherapy

Methods

The clinical information and RNA-seq data of ccRCC patients were collected from the TCGA dataset to first explore differential pyroptosis-related genes (PRGs). Univariate Cox regression and consensus clustering were applied to identify ccRCC subtypes. The prognostic PRGs were subjected to LASSO regression analysis to establish a prognostic model and to investigate its value and function. Finally, the relationship of the model immunity checkpoints and immunity infiltration was assessed.

Results

The receiver operating characteristic (ROC) showed that the 1-year, 3-year, and 5-year prediction rates of the prognostic model were 0.715, 0.693, and 0.732, respectively. The high-risk group had lower overall survival and higher stage than the low-risk group. Functional enrichment analysis showed that PRGs were significantly enriched mainly in the PPAR pathway, inflammatory pathway, and immune activity. ccRCC patient prognosis correlates with immune components in the microenvironment, and immune checkpoint molecules are significantly expressed in the high-risk group. Immunotherapy may be effective in the high-risk group.

Conclusion

Pyroptosis-related gene has an important impact on the progression of ccRCC and can be used as an independent predictor of patient prognosis. In addition, immune checkpoint molecules are significantly upregulated in high-risk populations, which may be a potential target for immunotherapy.

A Comparative Review of Pyroptosis in Mammals and Fish

Pyroptosis is a form of programmed cell death, which is executed by gasdermin family proteins. Under the stimulation of pathogen- and/or damage-associated molecular patterns, pattern recognition receptors (PRRs) such as Nod like receptors could recruit apoptosis-associated speck-like protein containing a CARD (ASC) and pro-caspases to form inflammasomes and then activate caspases through various pathways. The activated caspases then cleave gasdermin family proteins, and N-terminal (NT) domains of gasdermins were released to form oligomeric pores, resulting in the increased membrane permeability, cell swelling, and final pyroptosis. During this process, caspases also promote the maturation and release of inflammatory cytokines such as IL-1β and IL-18, thus pyroptosis is also named inflammatory cell death. Unlike numerous gasdermin family proteins in mammals, only gasdermin E (GSDME) has been identified in fish. GSDME in fish can be cleaved by caspase-a/-b to release its NT domain and induce pyroptosis. Studies indicated that pyroptosis in fish mainly depends on NLR family pyrin domain-containing 3 (NLRP3) inflammasome. ASC and different caspase proteins also were identified in different fish species. The influences of pathogenic microorganism infection and environmental pollutants on fish pyroptosis were studied in recent years. Considering that fish living environment is affected by multiple factors such as water salinity, temperature, oxygen supply, and highly fluctuating food supply, the in-depth research about fish pyroptosis will contribute to revealing the mechanism of pyroptosis during evolution.

Pyroptosis-related lncRNAs are potential biomarkers for predicting prognoses and immune responses in patients with UCEC

Uterine corpus endometrial carcinoma (UCEC) is a malignant disease globally, and there is no unified prognostic signature at present. In our study, two clusters were identified. Cluster 1 showed better prognosis and higher infiltration level, such as tumor microenvironment (TME), tumor mutation burden (TMB), and immune checkpoint genes expression. Gene set enrichment analysis (GSEA) indicated that some tumor-related pathways and immune-associated pathways were exposed. What is more, six pyroptosis-related long noncoding RNAs (lncRNAs) (PRLs) were applied to establish a prognostic signature through multiple Cox regression analysis. In both training and testing sets, patients with higher risk score had poorer survival than patients with low risk. The area under the curve (AUC) of receiver operating characteristic (ROC) curves performed that the survival probability was better in people with lower risk score. Mechanism analysis revealed that high risk score was correlated with reduced immune infiltration and T cells exhaustion, matching the definition of an "immune-desert" phenotype. Patients with lower risk score were characterized by higher immune checkpoint gene expression and TMB and have a sensitive response to immunotherapy and chemotherapy compared with patients with high risk score. The signature has accurate prediction ability of UCEC and is a promising therapeutic target to improve the effect of immunotherapy.

A Pyroptosis-Related Gene Signature to Predict Patients’ Prognosis and Immune Landscape in Liver Hepatocellular Carcinoma

Background

Liver hepatocellular carcinoma (LIHC) is a malignance with high incidence and recurrence. Pyroptosis is a programed cell death pattern which both activates the effective immune response and causes cell damage. However, their potential applications of pyroptosis-related genes (PRGs) in the prognostic evaluation and immunotherapy of LIHC are still rarely discussed.

Methods

Comprehensive bioinformatics analyses based on TCGA-LIHC dataset were performed in the current study.

Results

A total of 33 PRGs were selected to perform the current study. Of these 33 PRGs, 26 PRGs with upregulation or downregulation in LIHC tissues were identified. We also summarized the related genetic mutation variation landscape. GO and KEGG pathway analysis demonstrated that these 26 PRGs were primarily associated with pyroptosis, positive regulation of interleukin-1 beta production, and NOD-like receptor signaling pathway. An unfavorable OS appeared in LIHC patients with high CASP3, CASP4, CASP6, CASP8, GPX4, GSDMA, GSDME, NLRP3, NLRP7, NOD1, NOD2, PLCG1, and SCAF11 expression and low NLRP6 expression. A prognostic signature constructed by the above 14 prognostic PRGs had moderate to high accuracy to predict LIHC patients' prognosis. And risk score was correlated with the expression of CASP6, CASP8, GPX4, GSDMA, GSDME, NLRP6, and NOD2. Of these 7 genes, CASP8 was identified as the core gene in PPI network. Moreover, lncRNA MIR17HG/hsa-miRNA-130b-3p/CASP8 regulatory axis in LIHC was also detected.

Conclusions

The current study indicated the crucial role of PRGs in the prognostic evaluation of LIHC patients and their correlations with tumor microenvironment in LIHC.

Inhibition of FOSL2 aggravates the apoptosis of ovarian cancer cells by promoting the formation of inflammasomes

Background

Ovarian cancer is a common gynecological malignancy among female patients and poses a serious threat to women’s health. Although it has been established that Fos-like antigen 2 (FOSL2) is linked to ovarian cancer (OC), its exact role in the development of OC remains unknown.

Objective

This article aims to investigate the role of FOSL2 in ovarian cancer development.

Methods

FOSL2 expression in ovarian carcinoma and adjacent tissues was assessed using real-time fluorescent quantitative PCR and western blot. We constructed OE/sh-FOSL2 plasmids and Caspase-1 specific inhibitors (Yvad-CMK) and transfected A 2780 cells with them to identify the relevant cell functions. Furthermore, we used western blot assay to determine the changes in expression of apoptosis-associated speck-like protein containing a CARD (ASC), cysteine aspartate-specific proteasezymogen procaspase 1 (pro-caspase-1), cysteinyl aspartate-specific proteinase-1 (caspase-1), interleukin-1β precursor (pro-IL-1β), interleukin-1β (IL-1β), interleukin-18 precursor (pro-IL-18), and interleukin-18 (IL-18). In addition, we measured the concentration of IL-1β and IL-18 using an enzyme-linked immunosorbent assay (ELISA). Moreover, Tthe level of lactate dehydrogenase (LDH) in the cell supernatant was measured by LDH release assay kit.

Results

The expression of FOSL2 was significantly higher compared with the surrounding tissues. The proliferation, migration, and invasion of A2780 cells were enhanced after transfection with OE-FOSL2 plasmids; however, the cell apoptosis was significantly decreased. When FOSL2 was overexpressed, the inflammasome-associated proteins such as ASC, caspase-1, IL-1β, and IL-18 were downregulated. Furthermore, FOSL2 induced apoptosis and activated the production of inflammasomes in A2780 cells. Co-therapy with Yvad-CMK and substantially inhibited apoptosis and activation of inflammasomes.

Conclusions

Inhibition of FOSL2 promotes the apoptosis of OC cells by mediating the formation of an inflammasome.

Role of PKM2-Mediated Immunometabolic Reprogramming on Development of Cytokine Storm

The cytokine storm is a marker of severity of various diseases and increased mortality. The altered metabolic profile and energy generation of immune cells affects their activation, exacerbating the cytokine storm. Currently, the emerging field of immunometabolism has highlighted the importance of specific metabolic pathways in immune regulation. The glycolytic enzyme pyruvate kinase M2 (PKM2) is a key regulator of immunometabolism and bridges metabolic and inflammatory dysfunction. This enzyme changes its conformation thus walks in different fields including metabolism and inflammation and associates with various transcription factors. This review summarizes the vital role of PKM2 in mediating immunometabolic reprogramming and its role in inducing cytokine storm, with a focus on providing references for further understanding of its pathological functions and for proposing new targets for the treatment of related diseases.

Pyroptosis: mechanisms and diseases

Currently, pyroptosis has received more and more attention because of its association with innate immunity and disease. The research scope of pyroptosis has expanded with the discovery of the gasdermin family. A great deal of evidence shows that pyroptosis can affect the development of tumors. The relationship between pyroptosis and tumors is diverse in different tissues and genetic backgrounds. In this review, we provide basic knowledge of pyroptosis, explain the relationship between pyroptosis and tumors, and focus on the significance of pyroptosis in tumor treatment. In addition, we further summarize the possibility of pyroptosis as a potential tumor treatment strategy and describe the side effects of radiotherapy and chemotherapy caused by pyroptosis. In brief, pyroptosis is a double-edged sword for tumors. The rational use of this dual effect will help us further explore the formation and development of tumors, and provide ideas for patients to develop new drugs based on pyroptosis.

Regulated Necrotic Cell Death in Alternative Tumor Therapeutic Strategies

The treatment of tumors requires the induction of cell death. Radiotherapy, chemotherapy, and immunotherapy are administered to kill cancer cells; however, some cancer cells are resistant to these therapies. Therefore, effective treatments require various strategies for the induction of cell death. Regulated cell death (RCD) is systematically controlled by intracellular signaling proteins. Apoptosis and autophagy are types of RCD that are morphologically different from necrosis, while necroptosis, pyroptosis, and ferroptosis are morphologically similar to necrosis. Unlike necrosis, regulated necrotic cell death (RNCD) is caused by disruption of the plasma membrane under the control of specific proteins and induces tissue inflammation. Various types of RNCD, such as necroptosis, pyroptosis, and ferroptosis, have been used as therapeutic strategies against various tumor types. In this review, the mechanisms of necroptosis, pyroptosis, and ferroptosis are described in detail, and a potential effective treatment strategy to increase the anticancer effects on apoptosis- or autophagy-resistant tumor types through the induction of RNCD is suggested.

A Small Molecule Stabilizer of the MYC G4-Quadruplex Induces Endoplasmic Reticulum Stress, Senescence and Pyroptosis in Multiple Myeloma

Simple Summary

The DNA G-quadruplex (G4) present in the promoter of the MYC oncogene, commonly amplified in cancers, including multiple myeloma, represents a potential anti-cancer target. A previously identified MYC G4-stablizer, which demonstrated cytotoxicity and senescence in myeloma cells, was discovered to induce endoplasmic reticulum stress and non-apoptotic cell death, pyroptosis. Cancers including myeloma escape apoptosis through upregulation of anti-apoptotic proteins and drug resistance; therefore, induction of pyroptosis provides an alternate therapeutic option. Thus, our study provides a disease-specific experimental strategy for identifying new investigational drugs in cancer treatment.

Abstract

New approaches to target MYC include the stabilization of a guanine-rich, G-quadruplex (G4) tertiary DNA structure in the NHE III region of its promoter. Recent screening of a small molecule microarray platform identified a benzofuran, D089, that can stabilize the MYC G4 and inhibit its transcription. D089 induced both dose- and time-dependent multiple myeloma cell death mediated by endoplasmic reticulum induced stress. Unexpectedly, we uncovered two mechanisms of cell death: cellular senescence, as evidenced by increased levels of p16, p21 and γ-H2AX proteins and a caspase 3-independent mechanism consistent with pyroptosis. Cells treated with D089 exhibited high levels of the cleaved form of initiator caspase 8; but failed to show cleavage of executioner caspase 3, a classical apoptotic marker. Cotreatment with the a pan-caspase inhibitor Q-VD-OPh did not affect the cytotoxic effect of D089. In contrast, cleaved caspase 1, an inflammatory caspase downstream of caspases 8/9, was increased by D089 treatment. Cells treated with D089 in addition to either a caspase 1 inhibitor or siRNA-caspase 1 showed increased IC₅₀ values, indicating a contribution of cleaved caspase 1 to cell death. Downstream effects of caspase 1 activation after drug treatment included increases in IL1B, gasdermin D cleavage, and HMGB1 translocation from the nucleus to the cytoplasm. Drug treated cells underwent a ‘ballooning’ morphology characteristic of pyroptosis, rather than ‘blebbing’ typically associated with apoptosis. ASC specks colocalized with NLRP3 in proximity ligation assays after drug treatment, indicating inflammasome activation and further confirming pyroptosis as a contributor to cell death. Thus, the small molecule MYC G4 stabilizer, D089, provides a new tool compound for studying pyroptosis. These studies suggest that inducing both tumor senescence and pyroptosis may have therapeutic potential for cancer treatment.

Nanostructured toxins for the selective destruction of drug-resistant human CXCR4+ colorectal cancer stem cells

Current therapies fail to eradicate colorectal Cancer Stem Cells (CSCs). One of the proposed reasons for this failure is the selection, by chemotherapy exposure, of resistant cells responsible for tumor recurrence. In this regard, CXCR4 overexpression in tumor associates with resistance and poor prognosis in colorectal cancer (CRC) patients. In this study, the effectiveness of engineered CXCR4-targeted self-assembling toxin nanoparticles has been explored in the selective killing of CXCR4⁺ human colon-CSCs compared to 5-Fluorouracil and Oxaliplatin, both classical CRC chemotherapeutic agents. To assess this, 3D spheroid colon-CSCs cultures directly derived from CRC patients and CRC-CSC spheroid-derived tumor mouse models were developed. In these animal models, nanostructured toxins show highly selective induction of pyroptosis in the absence of apoptosis, thus having a great potential to overcome tumor resistance, since the same tumor models show resistance to chemotherapeutics. Results set the basis for further development of more efficient therapies focused on selective CXCR4⁺ CSCs elimination activating non-apoptotic mechanisms and represent a pre-clinical proof of concept for the use of CSCs-targeted nanostructured toxins as protein drugs for CRC therapy.

Induction of Pyroptosis and Its Implications in Cancer Management

Pyroptosis is a gasdermins mediated programmed cell death, which has been widely studied in inflammatory disease models. Recently, there are growing evidences that pyroptosis can be chemically induced in cancer cells without any bacterial or viral infection. Pyroptosis may affect all stages of carcinogenesis and has become a new topic in cancer research. In this review, we first briefly introduced pyroptosis. In the subsequent section, we discussed the induction of pyroptosis in cancer and its potential role as a promising target for cancer therapy. In addition, the biological characteristics of gasdermin D (GSDMD) and gasdermin E (GSDME), two important pyroptosis substrates, and their prognostic role in cancer management were reviewed. These results help us to understand the pathogenesis of cancer and develop new drugs, which based on pyroptosis modulation, for cancer patients.

Downregulation of LncRNA-XIST inhibited development of non-small cell lung cancer by activating miR-335/SOD2/ROS signal pathway mediated pyroptotic cell death

LncRNA-XIST participated in the regulation of Non-small cell lung cancer (NSCLC) progression, but the underlying mechanisms are still unclear. This study showed that LncRNA-XIST aberrantly overexpressed in either NSCLC tissues or cell lines comparing to their paired control groups. Knock-down of LncRNA-XIST promoted NSCLC cell apoptosis and inhibited cell proliferation, which were reversed by synergistically treating cells with pyroptosis inhibitor Necrosulfonamide (NSA). In addition, knock-down of LncRNA-XIST also promoted reactive oxygen species (ROS) production and NLRP3 inflammasome activation. In parallel, ROS scavenger N-acetyl cysteine (NAC) abrogated the effects of downregulated LncRNA-XIST on NSCLC cell pyroptosis. Furthermore, miR-335 was the downstream target of LncRNA-XIST and overexpressed LncRNA-XIST increased SOD2 expression levels by sponging miR-335. Mechanistically, miR-335 inhibitor reversed the effects of downregulated LncRNA-XIST on ROS levels and cell pyroptosis, which were abrogated by synergistically knocking down SOD2. Taken together, knock-down of LncRNA-XIST inhibited NSCLC progression by triggering miR-335/SOD2/ROS signal pathway mediated pyroptotic cell death.