A bioorthogonal system reveals antitumour immune function of pyroptosis

A new silicon phthalocyanine dye induces pyroptosis in prostate cancer cells during photoimmunotherapy

Photoimmunotherapy (PIT) combines the specificity of antibodies with the cytotoxicity of light activatable photosensitizers (PS) and is a promising new cancer therapy. We designed and synthesized, in a highly convergent manner, the silicon phthalocyanine dye WB692-CB2, which is novel for being the first light-activatable PS that can be directly conjugated via a maleimide linker to cysteines. In the present study we conjugated WB692-CB2 to a humanized antibody with engineered cysteines in the heavy chains that specifically targets the prostate-specific membrane antigen (PSMA). The resulting antibody dye conjugate revealed high affinity and specificity towards PSMA-expressing prostate cancer cells and induced cell death after irradiation with red light. Treated cells exhibited morphological characteristics associated with pyroptosis. Mechanistic studies revealed the generation of reactive oxygen species, triggering a cascade of intracellular events involving lipid peroxidation, caspase-1 activation, gasdermin D cleavage and membrane rupture followed by release of pro-inflammatory cellular contents. In first in vivo experiments, PIT with our antibody dye conjugate led to a significant reduction of tumor growth and enhanced overall survival in mice bearing subcutaneous prostate tumor xenografts. Our study highlights the future potential of the new phthalocyanine dye WB692-CB2 as PS for the fluorescence-based detection and PIT of cancer, including local prostate tumor lesions, and systemic activation of anti-tumor immune responses by the induction of pyroptosis.

Small-molecule GSDMD agonism in tumors stimulates antitumor immunity without toxicity

Gasdermin-mediated inflammatory cell death (pyroptosis) can activate protective immunity in immunologically cold tumors. Here, we performed a high-throughput screen for compounds that could activate gasdermin D (GSDMD), which is expressed widely in tumors. We identified 6,7-dichloro-2-methylsulfonyl-3-N-tert-butylaminoquinoxaline (DMB) as a direct and selective GSDMD agonist that activates GSDMD pore formation and pyroptosis without cleaving GSDMD. In mouse tumor models, pulsed and low-level pyroptosis induced by DMB suppresses tumor growth without harming GSDMD-expressing immune cells. Protection is immune-mediated and abrogated in mice lacking lymphocytes. Vaccination with DMB-treated cancer cells protects mice from secondary tumor challenge, indicating that immunogenic cell death is induced. DMB treatment synergizes with anti-PD-1. DMB treatment does not alter circulating proinflammatory cytokine or leukocyte numbers or cause weight loss. Thus, our studies reveal a strategy that relies on a low level of tumor cell pyroptosis to induce antitumor immunity and raise the possibility of exploiting pyroptosis without causing overt toxicity.

Zinc-Nickel Bimetallic Hydroxide Nanosheets Activate the Paraptosis-Pyroptosis Positive Feedback Cycle for Enhanced Tumor Immunotherapy

Immunotherapy holds significant promise for cancer treatment. However, the highly immunosuppressive nature of solid tumors limits its effectiveness. Herein, we developed bioactive zinc-nickel hydroxide (ZnNi(OH)4) nanosheets (NSs) that can effectively initiate the paraptosis-pyroptosis positive feedback cycle through synergistic ionic effect, thereby mitigating the immunosuppression of solid tumors and enhancing the efficacy of immunotherapy. The acid-sensitive ZnNi(OH)4 NSs releases Ni2+ and Zn2+ in the weakly acidic tumor microenvironment. The released Ni2+ alleviated pyroptosis inhibition by inducing paraptosis and inhibiting autophagic flux. Concurrently, Ni2+ triggered release of endogenous Zn2+ within the cell through a coordination competition mechanism, further amplifying zinc overload-mediated pyroptosis. Interestingly, pyroptosis-associated oxidative stress and endoplasmic reticulum stress further promote Ni2+-mediated paraptosis, forming a positive feedback loop between pyroptosis and paraptosis. This process not only effectively kills tumor cells but also stimulates a strong inflammatory response, enhancing the antitumor immune response and immunotherapy efficacy. Overall, this study proposes an effective paraptosis-pyroptosis induction strategy based on metal ions and demonstrates the effectiveness of the positive feedback loop of paraptosis-pyroptosis in potentiating immunotherapy.

C6 and KLRG2 are pyroptosis subtype-related prognostic biomarkers and correlated with tumor-infiltrating lymphocytes in lung adenocarcinoma

Pyroptosis plays an important role in lung adenocarcinoma (LUAD). In this study, we aimed to explore the pyroptosis-related gene (PRG) expression pattern and to identify promising pyroptosis-related biomarkers to improve the prognosis of LUAD. The gene expression profiles and clinical information of LUAD patients were downloaded from the Cancer Genome Atlas (TCGA), and validation cohort information was extracted from the Gene Expression Omnibus database. Gene expression data were analyzed using the limma package and visualized using the ggplot2 package as well as the pheatmap package in R software. Functional enrichment analysis was also performed for the 44 differentially expressed PRGs (DEPRGs). Then, consensus clustering revealed pyroptosis-related tumor subtypes, and differentially expressed genes (DEGs) were screened according to the subtypes. Next, univariate Cox and multivariate Cox regression analyses were used to identify independent prognostic PRGs. After overlapping DEGs and the Lasso regression analysis-based prognostic genes, the predictive risk model was established and validated. Correlation analysis between PRGs and clinicopathological variables was also explored. Finally, the TIMER and TISIDB databases were used to further explore the correlation analysis between immune cell infiltration levels, the risk score, and clinicopathological variables in the predictive risk model. A total of 52 genes from the PubMed were identified as PRGs, and 44 of the 52 genes were pooled as DEPRGs. The most significant GO term was "collagen trimer" (P = 2.46E-13), and KEGG analysis results indicated that 44 DEPRGs were significantly enriched in Salmonella infection (P < 0.001). Then, consensus clustering analysis divided LUAD patients into two clusters, and a total of 79 DEGs were identified according to these cluster subtypes. Subsequently, univariate and multivariate Cox regression analyses were used to identify 12 genes that could serve as independent prognostic indicators and we also performed Lasso regression analysis and screened 23 DEGs. After overlapping 23 DEGs and 12 genes, only 4 (KLRG2, MAPK4, C6 and SFRP5) of 12 genes were selected for the further exploration of the prognostic pattern. Survival analysis results indicated that this risk model effectively predicted the prognosis (P < 0.001). Combined with the correlation analysis results between the 4 genes and clinicopathological variables, C6 and KLRG2 were screened as prognostic genes. In this study, we constructed a predictive risk model and identified two pyroptosis subtype-related gene expression patterns to improve the prognosis of LUAD. Understanding the subtypes of LUAD is helpful for accurately characterizing the LUAD and developing personalized treatment.

Pyroptosis induced by natural products and their derivatives for cancer therapy

Natural products, which are compounds extracted and/or refined from plants and microbes in nature, have great potential for the discovery of therapeutic agents, especially for infectious diseases and cancer. In recent years, natural products have been reported to induce multiple cell death pathways to exhibit antitumor effects. Among them, pyroptosis is a unique programmed cell death (PCD) characterized by continuous cell membrane permeability and intracellular content leakage. According to the canonical and noncanonical pathways, the formation of gasdermin-N pores involves a variety of transcriptional targets and post-translational modifications. Thus, tailored control of PCD may facilitate dying cells with sufficient immunogenicity to activate the immune system to eliminate other tumor cells. Therefore, we summarized the currently reported natural products or their derivatives and their nano-drugs that induce pyroptosis-related signaling pathways. We reviewed six main categories of bioactive compounds extracted from natural products, including flavonoids, terpenoids, polyphenols, quinones, artemisinins, and alkaloids. Correspondingly, the underlying mechanisms of how these compounds and their derivatives engage in pyroptosis are also discussed. Moreover, the synergistic effect of natural bioactive compounds with other antitumor therapies is proposed as a novel therapeutic strategy for traditional chemotherapy, radiotherapy, chemodynamic therapy, photodynamic therapy, photothermal therapy, hyperthermal therapy, and sonodynamic therapy. Consequently, we provide insights into natural products to develop a novel antitumor therapy or qualified adjuvant agents by inducing pyroptosis, which may eventually be applied clinically.

A dual-pathway pyroptosis inducer based on Au-Cu2-xSe@ZIF-8 enhances tumor immunotherapy by disrupting the zinc ion homeostasis

The regulation of intracellular ionic homeostasis to trigger antigen-specific immune responses has attracted extensive interest in tumor therapy. In this study, we developed a dual-pathway nanoreactor, Au-Cu2-xSe@ZIF-8@P18 NPs (ACS-Z-P NPs), which targets danger-associated molecular patterns (DAMPs) and releases Zn2+ and reactive oxygen species (ROS) within the tumor microenvironment (TME). Zn2+ released from the metal-organic frameworks (MOFs) was deposited in the cytoplasm, leading to aberrant transcription levels of intracellular zinc-regulated proteins and DNA damage, thereby inducing pyroptosis and immunogenic cell death (ICD) dependent on caspase1/gasdermin D (GSDMD) pathway. Furthermore, upon laser irradiation, ACS-Z-P NPs could break through the limitations of inherent defects of immunosuppression in TME, enhance ROS generation through a Fenton-like reaction cascade, which subsequently triggered the activation of inflammatory vesicles and the release of damage-associated molecular patterns (DAMPs). This cascade effect led to the amplification of pyroptosis and immunogenic cell death (ICD), thereby remodeling the immunosuppressed TME. Consequently, this process improved dendritic cell (DC) antigen presentation and augmented anti-tumor T-cell responses, effectively initiating antigen-specific immune responses and further enhancing pyroptosis and ICD. This study explores the therapeutic properties of these mechanisms in detail. STATEMENT OF SIGNIFICANCE: The synthesized Au-Cu2-xSe@ZIF-8@P18 nanoparticles (ACS-Z-Ps) can effectively enhance the body's immune response by regulating zinc ion levels within cells. This regulation leads to abnormal levels of zinc-regulated protein transcription and DNA damage, which induces cellular pyroptosis. As a result, antigen presentation to dendritic cells (DCs) is improved, and anti-tumor T-cell responses are enhanced. The ACS-Z-P NPs overcome the limitations of ROS deficiency and immunosuppression in the tumor microenvironment by using H2O2 in the tumor microenvironment through a Fenton-like reaction. This leads to an increased production of ROS and O2, remodeling of the immunosuppressed tumor microenvironment, and enhanced induction of cell pyroptosis and immunogenic cell death. ACS-Z-P NPs targeted B16 cells using the photosensitizer P18 in combination with PDT treatment. This approach significantly inhibited the proliferation of B16 cells and effectively inhibited tumor growth.

IRE1α silences dsRNA to prevent taxane-induced pyroptosis in triple-negative breast cancer

Chemotherapy is often combined with immune checkpoint inhibitor (ICIs) to enhance immunotherapy responses. Despite the approval of chemo-immunotherapy in multiple human cancers, many immunologically cold tumors remain unresponsive. The mechanisms determining the immunogenicity of chemotherapy are elusive. Here, we identify the ER stress sensor IRE1α as a critical checkpoint that restricts the immunostimulatory effects of taxane chemotherapy and prevents the innate immune recognition of immunologically cold triple-negative breast cancer (TNBC). IRE1α RNase silences taxane-induced double-stranded RNA (dsRNA) through regulated IRE1-dependent decay (RIDD) to prevent NLRP3 inflammasome-dependent pyroptosis. Inhibition of IRE1α in Trp53-/- TNBC allows taxane to induce extensive dsRNAs that are sensed by ZBP1, which in turn activates NLRP3-GSDMD-mediated pyroptosis. Consequently, IRE1α RNase inhibitor plus taxane converts PD-L1-negative, ICI-unresponsive TNBC tumors into PD-L1high immunogenic tumors that are hyper-sensitive to ICI. We reveal IRE1α as a cancer cell defense mechanism that prevents taxane-induced danger signal accumulation and pyroptotic cell death.

Synergistic immunotherapy with a calcium-based nanoinducer: evoking pyroptosis and remodeling tumor-associated macrophages for enhanced antitumor immune response

The challenges posed by low immunogenicity and the immunosuppressive tumor microenvironment (TME) significantly hinder the efficacy of cancer immunotherapy. Pyroptosis, characterized as a pro-inflammatory cell death pathway, emerges as a promising approach to augment immunotherapy by promoting immunogenic cell death (ICD). The predominance of M2 phenotype tumor-associated macrophages (TAMs) in the TME underscores the critical need for TAM reprogramming to mitigate this immunosuppression. Herein, we introduce a calcium-based, intelligent-responsive nanoinducer (CaZCH NPs), designed to concurrently initiate pyroptosis and remodel TAMs, thereby amplifying antitumor immunotherapy effects. Modified with hyaluronic acid, CaZCH NPs can target tumor cells. Once internalized, CaZCH NPs respond to the acidic environment, releasing Ca2+, curcumin and H2O2 to induce mitochondrial Ca2+ overload and oxidation stress, leading to caspase-3/GSDME-mediated cell pyroptosis. Concurrently, O2 produced by CaZCH and pro-inflammatory cytokines from pyroptotic cells work together to shift TAM polarization towards the M1 phenotype, effectively countering TME's immunosuppressive effect. Notably, the synergistic effect of Ca2+-mediated pyroptosis and TAM remodeling demonstrates superior antitumor efficiency in colorectal cancer models. The induced ICD, coupled with M1-type TAMs, effectively enhances immunogenicity and mitigates immunosuppression, promoting dendritic cell maturation and activating CD8+ T cell-dependent systemic antitumor immunity. Our study presents a promising synergistic strategy for achieving highly efficient immunotherapy using a simple calcium-based nanoinducer.

Bufalin CaCO3 Nanoparticles Triggered Pyroptosis through Calcium Overload via Na+/Ca2+ Exchanger Reverse for Cancer Immunotherapy

Bufalin is a promising active ingredient in traditional Chinese medicine but has shown limited anticancer applications due to its toxicity. Here, we report BCNPs@gel, a bufalin-containing CaCO3 nanoparticle hydrogel, for enhancing cancer treatment through inducing cellular pyroptosis. Under the tumor microenvironment's low pH conditions, bufalin and Ca2+ are released from the delivery system. Bufalin serves as a direct anticancer drug and a Na+/K+-ATPase inhibitor by forcing the Na+/Ca2+ exchanger to reverse its function, which transfers Ca2+ into cytoplasm and ultimately causes Ca2+ overload-triggered pyroptosis. Meanwhile, we found that bufalin can upregulate PD-L1 in tumor cells. In combination with the PD-1 antibody, the delivery system showed a greater performance during the cancer treatment. BCNPs@gel enhances antitumor efficiency, reduces systemic side effects, extends antitumor mechanism of bufalin, and provides new strategies for inducing pyroptosis and calcium overload in cancer immunotherapy via Na+/K+-ATPase inhibitor. This work provides an application model for numerous other traditional Chinese medicine ingredients.

Intermetallics triggering pyroptosis and disulfidptosis in cancer cells promote anti-tumor immunity

Pyroptosis, an immunogenic programmed cell death, could efficiently activate tumor immunogenicity and reprogram immunosuppressive microenvironment for boosting cancer immunotherapy. However, the overexpression of SLC7A11 promotes glutathione biosynthesis for maintaining redox balance and countering pyroptosis. Herein, we develop intermetallics modified with glucose oxidase (GOx) and soybean phospholipid (SP) as pyroptosis promoters (Pd2Sn@GOx-SP), that not only induce pyroptosis by cascade biocatalysis for remodeling tumor microenvironment and facilitating tumor cell immunogenicity, but also trigger disulfidptosis mediated by cystine accumulation to further promote tumor pyroptosis in female mice. Experiments and density functional theory calculations show that Pd2Sn nanorods with an intermediate size exhibit stronger photothermal and enzyme catalytic activity compared with the other three morphologies investigated. The peroxidase-mimic and oxidase-mimic activities of Pd2Sn cause potent reactive oxygen species (ROS) storms for triggering pyroptosis, which could be self-reinforced by photothermal effect, hydrogen peroxide supply accompanied by glycometabolism, and oxygen production from catalase-mimic activity of Pd2Sn. Moreover, the increase of NADP+/NADPH ratio induced by glucose starvation could pose excessive cystine accumulation and inhibit glutathione synthesis, which could cause disulfidptosis and further augment ROS-mediated pyroptosis, respectively. This two-pronged treatment strategy could represent an alternative therapeutic approach to expand anti-tumor immunotherapy.

PARP inhibitors enhance antitumor immune responses by triggering pyroptosis via TNF-caspase 8-GSDMD/E axis in ovarian cancer

BACKGROUND

In addition to their established action of synthetic lethality in tumor cells, poly(ADP-ribose) polymerase inhibitors (PARPis) also orchestrate tumor immune microenvironment (TIME) that contributes to suppressing tumor growth. However, it remains not fully understood whether and how PARPis trigger tumor-targeting immune responses.

METHODS

To decode the immune responses reshaped by PARPis, we conducted T-cell receptor (TCR) sequencing and immunohistochemical (IHC) analyses of paired clinical specimens before and after niraparib monotherapy obtained from a prospective study, as well as ID8 mouse ovarian tumors. To validate the induction of immunogenic cell death (ICD) by PARPis, we performed immunofluorescence/IHC staining with homologous recombination deficiency tumor cells and patient-derived xenograft tumor tissues, respectively. To substantiate that PARPis elicited tumor cell pyroptosis, we undertook comprehensive assessments of the cellular morphological features, cleavage of gasdermin (GSDM) proteins, and activation of TNF-caspase signaling pathways through genetic downregulation/depletion and selective inhibition. We also evaluated the critical role of pyroptosis in tumor suppression and immune activation following niraparib treatment using a syngeneic mouse model with implanting CRISPR/Cas9 edited Gsdme-/ - ID8 tumor cells into C57BL/6 mice.

RESULTS

Our findings revealed that PARPis augmented the proportion of neoantigen-recognized TCR clones and TCR clonal expansion, and induced an inflamed TIME characterized by increased infiltration of both innate and adaptive immune cells. This PARPis-strengthened immune response was associated with the induction of ICD, specifically identified as pyroptosis, which possessed distinctive morphological features and GSDMD/E cleavage. It was validated that the cleavage of GSDMD/E was due to elevated caspase 8 activity downstream of the TNFR1, rather than FAS and TRAIL-R. On PARP inhibition, the NF-κB signaling pathway was activated, leading to increased secretion of TNF-α and subsequent initiation of the TNFR1-caspase 8 cascade. Impeding pyroptosis through the depletion of Gsdme significantly compromised the tumor-suppressing effects of PARP inhibition and undermined the anti-immune response in the syngeneic ID8 mouse model.

CONCLUSIONS

PARPis induce a specific type of ICD called pyroptosis via TNF-caspase 8-GSDMD/E axis, resulting in an inflamed TIME and augmentation of tumor-targeting immune responses. These findings deepen our understanding of PARPis activities and point toward a promising avenue for synergizing PARPis with immunotherapeutic interventions.

TRIAL REGISTRATION NUMBER

NCT04507841.

Smart Bioorthogonal Nanozymes: From Rational Design to Appropriate Bioapplications

Bioorthogonal chemistry has provided an elaborate arsenal to manipulate native biological processes in living systems. As the great advancement of nanotechnology in recent years, bioorthogonal nanozymes are innovated to tackle the challenges that emerged in practical biomedical applications. Bioorthogonal nanozymes are uniquely positioned owing to their advantages of high customizability and tunability, as well as good adaptability to biological systems, which bring exciting opportunities for biomedical applications. More intriguingly, the great advancement in nanotechnology offers an exciting opportunity for innovating bioorthogonal catalytic materials. In this comprehensive review, the significant progresses of bioorthogonal nanozymes are discussed with both spatiotemporal controllability and high performance in living systems, and highlight their design principles and recent rapid applications. The remaining challenges and future perspectives are then outlined along this thriving field. It is expected that this review will inspire and promote the design of novel bioorthogonal nanozymes, and facilitate their clinical translation.

Characterization of AB598, a CD39 Enzymatic Inhibitory Antibody for the Treatment of Solid Tumors

AB598 is a CD39 inhibitory antibody being pursued for the treatment of solid tumors in combination with chemotherapy and immunotherapy. CD39 metabolizes extracellular adenosine triphosphate (eATP), an alarmin capable of promoting antitumor immune responses, into adenosine, an immuno-inhibitory metabolite. By inhibiting CD39, the consumption of eATP is reduced, resulting in a proinflammatory milieu in which eATP can activate myeloid cells to promote antitumor immunity. The preclinical characterization of AB598 provides a mechanistic rationale for combining AB598 with chemotherapy in the clinic. Chemotherapy can induce ATP release from tumor cells and, when preserved by AB598, both chemotherapy-induced eATP and exogenously added ATP promote the function of monocyte-derived dendritic cells via P2Y11 signaling. Inhibition of CD39 in the presence of ATP can promote inflammasome activation in in vitro-derived macrophages, an effect mediated by P2X7. In a MOLP8 murine xenograft model, AB598 results in full inhibition of intratumoral CD39 enzymatic activity, an increase in intratumoral ATP, a decrease of extracellular CD39 on tumor cells, and ultimately, control of tumor growth. In cynomolgus monkeys, systemic dosing of AB598 results in effective enzymatic inhibition in tissues, full peripheral and tissue target engagement, and a reduction in cell surface CD39 both in tissues and in the periphery. Taken together, these data support a promising therapeutic strategy of harnessing the eATP generated by standard-of-care chemotherapies to prime the tumor microenvironment for a productive antitumor immune response.

Biodegradable Persistent Luminescence Nanoparticles as Pyroptosis Inducer for High-Efficiency Tumor Immunotherapy

Pyroptosis possesses potent antitumor immune activity, making pyroptosis inducer development a promising direction for tumor immunotherapy. Persistent luminescence nanoparticles (PLNPs) are highly sensitive optical probes extensively employed in tumor diagnosis and therapy. However, a pyroptosis inducer based on PLNPs has not been reported yet. Herein, polyethylene glycol-poly lactic acid-co-glycolic acid (PEG-PLGA: PP) modified biodegradable CaS:Eu2+ (CSE@PP) PLNPs are synthesized as a pyroptosis inducer for tumor immunotherapy for the first time. The synthesized CSE@PP possesses biowindow persistent luminescence (PersL) and pH-responsive degradation properties, allowing it to remain stable under neutral pH but degrade when exposed to weak acid (pH < 6.5). During degradation within the tumor, CSE@PP constantly releases H2S and Ca2+ while its PersL gradually fades away. Thus, the PersL signal can self-monitor H2S and Ca2+ release. Furthermore, the released H2S and Ca2+ result in mitochondrial dysfunction and the inactivation of reactive oxygen species scavenging enzymes, synergistic facilitating intracellular oxidative stress, which induces caspase-1/GSDM-D dependent pyroptosis and subsequent antitumor immune responses. In a word, it is confirmed that CSE@PP can self-monitor H2S and Ca2+ release and pyroptosis-mediated tumor Immunotherapy. This work will facilitate biomedical applications of PLNPs and inspire pyroptosis-induced tumor immunotherapy.

Applications of pyroptosis activators in tumor immunotherapy

Contemporary progress in tumor immunotherapy has solidified its role as an effective approach in combating cancer. Nonetheless, the prevalent "immune cold" state within the tumor microenvironment poses a substantial barrier to its efficacy. Addressing this, pyroptosis-a gasdermin-mediated programmed cell death characterized by its inflammatory profile-emerges as a crucial mechanism. It catalyzes the release of vast quantities of pro-inflammatory cytokines and immunogens, potentially transforming immunosuppressive "cold" tumors into reactive "hot" ones. Herein, we will initially present an overview of pyroptosis as a distinct form of cell death, along with its molecular mechanisms. Subsequently, we will focus on introducing how pyroptosis activators are utilized in the field of tumor immunotherapy. Insights gained from applications of pyroptosis activators in tumor immunotherapy could lead to the development of safe and efficient pyroptosis activators, significantly enriching the arsenal for tumor immunotherapy.

Programmed Cascade Polydopamine Nanoclusters for Pyroptosis-Based Tumor Immunotherapy

Pyroptosis, an inflammatory cell death, plays a pivotal role in activating inflammatory response, reversing immunosuppression and enhancing anti-tumor immunity. However, challenges remain regarding how to induce pyroptosis efficiently and precisely in tumor cells to amplify anti-tumor immunotherapy. Herein, a pH-responsive polydopamine (PDA) nanocluster, perfluorocarbon (PFC)@octo-arginine (R8)-1-Hexadecylamine (He)-porphyrin (Por)@PDA-gambogic acid (GA)-cRGD (R-P@PDA-GC), is rationally design to augment phototherapy-induced pyroptosis and boost anti-tumor immunity through a two-input programmed cascade therapy. Briefly, oxygen doner PFC is encapsulated within R8 linked photosensitizer Por and He micelles as the core, followed by incorporation of GA and cRGD peptides modified PDA shell, yielding the ultimate R-P@PDA-GC nanoplatforms (NPs). The pH-responsive NPs effectively alleviate hypoxia by delivering oxygen via PFC and mitigate heat resistance in tumor cells through GA. Upon two-input programmed irradiation, R-P@PDA-GC NPs significantly enhance reactive oxygen species production within tumor cells, triggering pyroptosis via the Caspase-1/GSDMD pathway and releasing numerous inflammatory factors into the TME. This leads to the maturation of dendritic cells, robust infiltration of cytotoxic CD8+ T and NK cells, and diminution of immune suppressor Treg cells, thereby amplifying anti-tumor immunity.

Novel Arf1 Inhibitors Drive Cancer Stem Cell Aging and Potentiate Anti-Tumor Immunity

The small G protein Arf1 has been identified as playing a selective role in supporting cancer stem cells (CSCs), making it an attractive target for cancer therapy. However, the current Arf1 inhibitors have limited translational potential due to their high toxicity and low specificity. In this study, two new potent small-molecule inhibitors of Arf1, identified as DU101 and DU102, for cancer therapy are introduced. Preclinical tumor models demonstrate that these inhibitors triggered a cascade of aging in CSCs and enhance anti-tumor immunity in mouse cancer and PDX models. Through single-cell sequencing, the remodeling of the tumor immune microenvironment induced by these new Arf1 inhibitors is analyzed and an increase in tumor-associated CD8+ CD4+ double-positive T (DPT) cells is identified. These DPT cells exhibit superior features of active CD8 single-positive T cells and a higher percentage of TCF1+PD-1+, characteristic of stem-like T cells. The frequency of tumor-infiltrating stem-like DPT cells correlates with better disease-free survival (DFS) in cancer patients, indicating that these inhibitors may offer a novel cancer immunotherapy strategy by converting the cold tumor immune microenvironment into a hot one, thus expanding the potential for immunotherapy in cancer patients.

Starvation-induced phosphorylation activates gasdermin A to initiate pyroptosis

Pyroptosis, a pro-inflammatory form of programmed cell death, is crucial for host defense against pathogens and danger signals. Proteolytic cleavage of gasdermin proteins B-E (GSDMB-GSDME) is well established as a trigger for pyroptosis, but the intracellular activation mechanism of GSDMA remains elusive. Here, we demonstrate that severe starvation induces pyroptosis through phosphorylation-induced activation of GSDMA. Nutrient stresses stimulate GSDMA activation via phosphorylation mediated by Unc-51-like autophagy-activating kinase 1 (ULK1). Phosphorylation of Ser353 on human GSDMA by ULK1 or the phospho-mimetic Ser353Asp mutant of GSDMA liberates GSDMA from auto-inhibition, facilitating its membrane targeting and initiation of pyroptosis. To further validate the significance of GSDMA phosphorylation, we generated a constitutively active mutant Ser354Asp of mouse Gsdma, which induced skin inflammation and hyperplasia in mice, reminiscent of phenotypes with activated Gsdma. This study uncovers phosphorylation of GSDMA as a mechanism underlying pyroptosis initiation and cellular response to nutrient stress.

Local anesthetic tetracaine hydrochloride induces pyroptosis via caspase-3/gasdermin E in uveal melanoma

BACKGROUND

Evasion of pyroptosis is an effective survival strategy employed by cancer cells to evade immune cell attacks and drug-induced cytotoxicity. Exploring potent molecules capable of inducing pyroptosis in cancer cells has significant clinical implications for the control of cancer progression. Unexpectedly, we found that the local anesthetic tetracaine hydrochloride (TTC) induced pyroptosis, specifically in uveal melanoma but not in acral or cutaneous melanoma.

METHODS

We investigated the effects of TTC on various melanoma cell lines and performed transcriptome sequencing of TTC-treated uveal melanoma cells. The role of gasdermin E (GSDME), an executive protein responsible for pyroptosis, was explored using CRISPR-Cas13d knockdown, caspase-3 inhibitor treatment, and western blot analysis. Differential gene expression and pathway enrichment analyses were performed. Furthermore, we used tissue microarrays to assess GSDME expression levels in melanoma tissues from different anatomical sites.

RESULTS

TTC significantly induced pyroptosis specifically in uveal melanoma cells with high GSDME expression levels. TTC treatment could lead to GSDME cleavage by the caspase-3 in uveal melanoma C918 cells. GSDME knockdown or caspase-3 inhibition suppressed TTC-induced pyroptosis. Transcriptome analysis revealed differentially expressed genes enriched in signaling pathways related to pyroptosis, immunity, and cytokines.

CONCLUSIONS

This study showed that the local anesthetic TTC effectively induces pyroptosis in uveal melanoma through the caspase-3/GSDME pathway, highlighting its potential application in immunotherapy. Notably, the use of TTC has potential as an agent for inducing pyroptosis and as an adjuvant anticancer therapy in uveal melanoma.

Pyroptosis in health and disease: mechanisms, regulation and clinical perspective

Pyroptosis is a type of programmed cell death characterized by cell swelling and osmotic lysis, resulting in cytomembrane rupture and release of immunostimulatory components, which play a role in several pathological processes. Significant cellular responses to various stimuli involve the formation of inflammasomes, maturation of inflammatory caspases, and caspase-mediated cleavage of gasdermin. The function of pyroptosis in disease is complex but not a simple angelic or demonic role. While inflammatory diseases such as sepsis are associated with uncontrollable pyroptosis, the potent immune response induced by pyroptosis can be exploited as a therapeutic target for anti-tumor therapy. Thus, a comprehensive review of the role of pyroptosis in disease is crucial for further research and clinical translation from bench to bedside. In this review, we summarize the recent advancements in understanding the role of pyroptosis in disease, covering the related development history, molecular mechanisms including canonical, non-canonical, caspase 3/8, and granzyme-mediated pathways, and its regulatory function in health and multiple diseases. Moreover, this review also provides updates on promising therapeutic strategies by applying novel small molecule inhibitors and traditional medicines to regulate pyroptosis. The present dilemmas and future directions in the landscape of pyroptosis are also discussed from a clinical perspective, providing clues for scientists to develop novel drugs targeting pyroptosis.

The therapeutic potential of andrographolide in cancer treatment

Cancer poses a substantial global health challenge, necessitating the widespread use of chemotherapy and radiotherapy. Despite these efforts, issues like resistance development and severe side effects remain. As such, the search for more effective alternatives is critical. Andrographolide, a naturally occurring compound, has recently gained attention for its extensive biological activities. This review explores the role of andrographolide in cancer therapy, especially focusing on the molecular mechanisms that drive its anti-tumor properties. It also examines innovative methods to enhance andrographolide's bioavailability, thus boosting its effectiveness against cancer. Notably, andrographolide has potential for use in combination with various clinical drugs, and both preclinical and clinical studies provide strong evidence supporting its broader anticancer applications. Additionally, this paper proposes future research directions for andrographolide's anti-cancer effects and discusses the challenges in its clinical usage along with current research efforts to address these issues. In summary, this review underscores andrographolide's potential roles and contributes to the development of improved cancer treatment strategies.

Devising Biocompatible, NIR-Activated Helical Pyroptosis Agents via 𝛑-Twisting Strategy for Promoting Antitumor Immunity

Specifically controlling cell pyroptosis is advantageous for oncotherapy as it allows simultaneous ablation of primary tumors and activation of immunogenicity of tumor environment. Herein, a facile and robust strategy is presented to construct efficient NIR-activated helical pyroptosis agents (PyroAs) with negligible dark cytotoxicity. It is demonstrated that the construction of four intramolecular B-X bonds (X = O or N) within the BODIPY chromophore enforces a significant twisting of its π-conjugation, yielding a variety of helical HBD molecules with desired high photosensitivity and negligible dark toxicity. A robust approach is established to extend HBD into the near-infrared (NIR) region through site-selective incorporation of an electron-withdrawing ester moiety. It is also proved that targeted delivery of the NIR-activated HBD-ER to the endoplasmic reticulum (ER) specifically activates pyroptosis pathway by equipping it with an ER-targeting moiety. Finally, the favorable biocompatibility, excellent antitumor efficacy, and remarkable systematic immune response of this unique NIR-activated helical PyroAs are shown in vivo, demonstrating its potential application in solid tumor immunotherapy.

Locally unlocks prodrugs by radiopharmaceutical in tumor for cancer therapy

Chemotherapy is the first-line treatment for cancer, but its systemic toxicity can be severe. Tumor-selective prodrug activation offers promising opportunities to reduce systemic toxicity. Here, we present a strategy for activating prodrugs using radiopharmaceuticals. This strategy enables the targeted release of chemotherapeutic agents due to the high tumor-targeting capability of radiopharmaceuticals. [18F]FDG (2-[18F]-fluoro-2-deoxy-D-glucose), one of the most widely used radiopharmaceuticals in clinics, can trigger Pt(IV) complex for controlled release of axial ligands in tumors, it might be mediated by hydrated electrons generated by water radiolysis resulting from the decay of radionuclide 18F. Its application offers the controlled release of fluorogenic probes and prodrugs in living cells and tumor-bearing mice. Of note, an OxaliPt(IV) linker is designed to construct an [18F]FDG-activated antibody-drug conjugate (Pt-ADC). Sequential injection of Pt-ADC and [18F]FDG efficiently releases the toxin in the tumor and remarkably suppresses the tumor growth. Radiotherapy is booming as a perturbing tool for prodrug activation, and we find that [18F]FDG is capable of deprotecting various radiotherapy-removable protecting groups (RPGs). Our results suggest that tumor-selective radiopharmaceutical may function as a trigger, for developing innovative prodrug activation strategies with enhanced tumor selectivity.

Pyroptosis-associated genes and tumor immune response in endometrial cancer

The occurrence and progression of tumors are linked to the process of pyroptosis. However, the precise involvement of pyroptosis-associated genes (PRGs) in endometrial cancer (EC) remains uncertain. 29 PRGs were identified as being either up-regulated or down-regulated in EC. PRGs subgroup analysis demonstrated distinct survival outcomes and diverse responses to chemotherapy and immune checkpoint blockade therapy. A higher expression of GPX4 and NOD2, coupled with lower levels of CASP6, PRKACA, and NLRP2, were found to be significantly associated with higher overall survival (OS) rates (p < 0.05). Conversely, lower expression of NOD2 was linked to lower progression-free survival (p = 0.021) and advanced tumor stage(p = 0.0024). NOD2, NLRP2, and TNM stages were identified as independent prognostic factors (p < 0.001). The LASSO prognostic model exhibited a notable decrease in OS among EC patients in the high-risk score group (ROC-AUC10-years: 0.799, p = 0.00644). Furthermore, NOD2 displayed a positive correlation with the infiltration of immune cells and the expression of immune checkpoints (p < 0.001). GPX4 and CASP6 are significantly associated with TMB and MSI (RTMB = 0.39; RMSI = 0.23). Additionally, a substantial upregulation of NOD2 was confirmed in both EC cells and tissue, indicating a positive relationship between advanced TNM stage (p < 0.0001) and infiltration of M1 phenotype macrophages. Nonetheless, its impact on patient OS did not reach statistical significance (p = 0.141). Our findings have contributed to the advancement of a prognostic model for EC patients. NOD2 receptor-mediated pyroptosis mechanism potentially regulates tumor immunity and promotes the transformation of macrophages from the M2 phenotype to the M1 phenotype, which significantly impacts the progression of EC.

A Membrane-Anchoring Self-Assembling Peptide Allows Bioorthogonal Coupling of Type-I AIEgens for Pyroptosis-Induced Cancer Therapy

Enrichment of photosensitizers (PSs) on cancer cell membranes via bioorthogonal reactions is considered to be a very promising therapeutic modality. However, azide-modified sugars-based metabolic labeling processes usually lack targeting and the labeling speed is relatively slow. Moreover, it has been rarely reported that membrane-anchoring pure type-I PSs can induce cancer cell pyroptosis. Here, we report an alkaline phosphatase (ALP) and cholecystokinin-2 receptor (CCK2R) dual-targeting peptide named DBCO-pYCCK6, which can selectively and rapidly self-assemble on cancer cell membrane, and then bioorthogonal enrich type-I aggregation-induced emission luminogens (AIEgen) PSs (SAIE-N3) on the cell membrane. Upon light irradiation, the membrane-anchoring SAIE-N3 could effectively generate type-I reactive oxygen species (ROS) to induce gasdermin E (GSDME)-mediated pyroptosis. In vivo experiments demonstrated that the bioorthogonal combination strategy of peptide and AIEgen PSs could significantly inhibit tumor growth, which is accompanied by CD8+ cytotoxic T cell infiltration. This work provides a novel self-assembly peptide-mediated bioorthogonal reaction strategy to bridge the supramolecular self-assembly and AIE field through strain-promoted azide-alkyne cycloaddition (SPAAC) and elucidates that pure type-I membrane-anchoring PSs can be used for cancer therapy via GSDME-mediated pyroptosis.

HDAC inhibitor regulates the tumor immune microenvironment via pyroptosis in triple negative breast cancer

Pyroptosis, an inflammatory form of cell death, promotes the release of immunogenic substances and stimulates immune cell recruitment, a process, which could turn cold tumors into hot ones. Thus, instigating pyroptosis in triple-negative breast cancer (TNBC) serves as a viable method for restoring antitumor immunity. We analyzed the effects of Histone Deacetylase Inhibitors (HDACi) on TNBC cells using the Cell Counting Kit-8 and colony formation assay. Apoptosis and lactate dehydrogenase (LDH) release assays were utilized to determine the form of cell death. The pyroptotic executor was validated by quantitative real-time polymerase chain reaction and western blot. Transcriptome was analyzed to investigate pyroptosis-inducing mechanisms. A subcutaneously transplanted tumor model was generated in BALB/c mice to evaluate infiltration of immune cells. HDACi significantly diminished cell proliferation, and pyroptotic "balloon"-like cells became apparent. HDACi led to an intra and extracellular material exchange, signified by the release of LDH and the uptake of propidium iodide. Among the gasdermin family, TNBC cells expressed maximum quantities of GSDME, and expression of GSDMA, GSDMB, and GSDME were augmented post HDACi treatment. Pyroptosis was instigated via the activation of the caspase 3-GSDME pathway with the potential mechanisms being cell cycle arrest and altered intracellular REDOX balance due to aberrant glutathione metabolism. In vivo experiments demonstrated that HDACi can activate pyroptosis, limit tumor growth, and escalate CD8+ lymphocyte and CD11b+ cell infiltration along with an increased presence of granzyme B in tumors. HDACi can instigate pyroptosis in TNBC, promoting infiltration of immune cells and consequently intensifying the efficacy of anticancer immunity.

Potentially functional variants of CHMP4A and PANX1 in the pyroptosis-related pathway predict survival of patients with non-oropharyngeal head and neck squamous cell carcinoma

BACKGROUND

Pyroptosis has been implicated in the advancement of various cancers. Triggering pyroptosis within tumors amplifies the immune response, thereby fostering an antitumor immune environment. Nonetheless, few published studies have evaluated associations between functional variants in the pyroptosis-related genes and clinical outcomes of patients with non-oropharyngeal head and neck squamous cell carcinoma (NON-ORO HNSCC).

METHODS

We conducted an association study of 985 NON-ORO HNSCC patients who were randomly divided into two groups: the discovery group of 492 patients and the replication group of 493 patients. We used Cox proportional hazards regression analysis to examine associations between genetic variants of the pyroptosis-related genes and survival of patients with NON-ORO HNSCC. Bayesian false discovery probability (BFDP) was used for multiple testing correction. Functional annotation was applied to the identified survival-associated genetic variants.

RESULTS

There are 8254 single-nucleotide polymorphisms (SNPs) located in 82 pyroptosis-related genes, of which 202 SNPs passed multiple testing correction with BFDP < 0.8 in the discovery and six SNPs retained statistically significant in the replication. In subsequent stepwise multivariable Cox regression analysis, two independent SNPs (CHMP4A rs1997996 G > A and PANX1 rs56175344 C > G) remained significant with an adjusted hazard ratios (HR) of 1.31 (95% confidence interval [CI] = 1.09-1.57, p = 0.004) and 0.65 (95% CI = 0.51-0.83, p = 0.0005) for overall survival (OS), respectively. Further analysis of the combined genotypes revealed progressively worse OS associated with the number of unfavorable genotypes (ptrend < 0.0001 and 0.021 for OS and disease-specific survival, respectively). Moreover, both PANX1 rs56175344G and CHMP4A rs1997996A alleles were correlated with reduced mRNA expression levels.

CONCLUSIONS

Genetic variants in the pyroptosis pathway genes may predict the survival of NON-ORO HNSCC patients, likely by reducing the gene expression, but our findings need to be replicated by larger studies.

Emerging role of immunogenic cell death in cancer immunotherapy: Advancing next-generation CAR-T cell immunotherapy by combination

Immunogenic cell death (ICD) is a stress-driven form of regulated cell death (RCD) in which dying tumor cells' specific signaling pathways are activated to release damage-associated molecular patterns (DAMPs), leading to the robust anti-tumor immune response as well as a reversal of the tumor immune microenvironment from "cold" to "hot". Chimeric antigen receptor (CAR)-T cell therapy, as a landmark in anti-tumor immunotherapy, plays a formidable role in hematologic malignancies but falls short in solid tumors. The Gordian knot of CAR-T cells for solid tumors includes but is not limited to, tumor antigen heterogeneity or absence, physical and immune barriers of tumors. The combination of ICD induction therapy and CAR-T cell immunotherapy is expected to promote the intensive use of CAR-T cell in solid tumors. In this review, we summarize the characteristics of ICD, stress-responsive mechanism, and the synergistic effect of various ICD-based therapies with CAR-T cells to effectively improve anti-tumor capacity.

Iridium(III) Photosensitizers Induce Simultaneous Pyroptosis and Ferroptosis for Multi-Network Synergistic Tumor Immunotherapy

The integration of pyroptosis and ferroptosis hybrid cell death induction to augment immune activation represents a promising avenue for anti-tumor treatment, but there is a lack of research. Herein, we developed two iridium (III)-triphenylamine photosensitizers, IrC and IrF, with the capacity to disrupt redox balance and induce photo-driven cascade damage to DNA and Kelch-like ECH-associated protein 1 (KEAP1). The activation of the absent in melanoma 2 (AIM2)-related cytoplasmic nucleic acid-sensing pathway, triggered by damaged DNA, leads to the induction of gasdermin D (GSDMD)-mediated pyroptosis. Simultaneously, iron homeostasis, regulated by the KEAP1/nuclear factor erythroid 2-related factor 2 (NRF2)/heme oxygenase 1 (HO-1) pathway, serves as a pivotal bridge, facilitating not only the induction of gasdermin E (GSDME)-mediated non-canonical pyroptosis, but also ferroptosis in synergy with glutathione peroxidase 4 (GPX4) depletion. The collaborative action of pyroptosis and ferroptosis generates a synergistic effect that elicits immunogenic cell death, stimulates a robust immune response and effectively inhibits tumor growth in vivo. Our work introduces the first metal-based small molecule dual-inducers of pyroptosis and ferroptosis for potent cancer immunotherapy, and highlights the significance of iron homeostasis as a vital hub connecting synergistic effects of pyroptosis and ferroptosis.

Nanoparticle-mediated cell pyroptosis: a new therapeutic strategy for inflammatory diseases and cancer

Pyroptosis, a lytic form of cell death mediated by the gasdermin family, is characterized by cell swelling and membrane rupture. Inducing pyroptosis in cancer cells can enhance antitumor immune responses and is a promising strategy for cancer therapy. However, excessive pyroptosis may trigger the development of inflammatory diseases due to immoderate and continuous inflammatory reactions. Nanomaterials and nanobiotechnology, renowned for their unique advantages and diverse structures, have garnered increasing attention owing to their potential to induce pyroptosis in diseases such as cancer. A nano-delivery system for drug-induced pyroptosis in cancer cells can overcome the limitations of small molecules. Furthermore, nanomedicines can directly induce and manipulate pyroptosis. This review summarizes and discusses the latest advancements in nanoparticle-based treatments with pyroptosis among inflammatory diseases and cancer, focusing on their functions and mechanisms and providing valuable insights into selecting nanodrugs for pyroptosis. However, the clinical application of these strategies still faces challenges owing to a limited understanding of nanobiological interactions. Finally, future perspectives on the emerging field of pyroptotic nanomaterials are presented.

Nanohybrid-Based Redox Homeostasis Perturbators Escaped from Early Lysosomes toward Amplified Sensitization of Tumor Cells and Photothermally Maneuvered Pyroptosis Therapy

Reactive oxygen species (ROS) hold great potential in tumor pyroptosis therapy, yet they are still limited by short species lifespan and limited diffusion distance. Inducing cells into a metastable state and then applying external energy can effectively trigger pyroptosis, but systemic sensitization still faces challenges, such as limited ROS content, rapid decay, and short treatment windows. Herein, a nanohybrid-based redox homeostasis-perturbator system was designed that synergistically induce early lysosomal escape, autophagy inhibition, and redox perturbation functions to effectively sensitize cells to address these challenges. Specifically, weakly alkaline layered double hydroxide nanosheets (LDH NSs) with pH-responsive degradation properties enabled early lysosomal escape within 4 h, releasing poly(L-dopa) nanoparticles for inducing catechol-quinone redox cycling in the cytoplasm. The intracellular ROS levels were systematically rebounded by 3-4 times in tumor cells and lasted for over 4 h. Subsequently induced lysosomal stress and Ca2+ signaling activation resulted in severe mitochondrial dysfunction, as well as a perilous metastable state. Thereby, sequential near-infrared light was applied to trigger amplified stress through a local photothermal conversion. This led to sufficiently high levels of cleaved caspase-1 and GSDMD activation (2.5-2.8-fold increment) and subsequent pyroptosis response. In addition, OH- released by LDH elevated pH to alleviate the limitation of glutathione depletion by quinones at acidic pH and inhibit protective autophagy. Largely secreted inflammatory factors (2.5-5.6-fold increment), efficient maturation of dendritic cells, and further immune stimulation were boosted for tumor inhibition as a consequence. This study offers a new paradigm and insights into the synergy of internal systematic cellular sensitization and sequential external energy treatment to achieve tumor suppression through pyroptosis.

Gold(III)-Induced Amide Bond Cleavage In Vivo: A Dual Release Strategy via π-Acid Mediated Allyl Substitution

Selective cleavage of amide bonds holds prominent significance by facilitating precise manipulation of biomolecules, with implications spanning from basic research to therapeutic interventions. However, achieving selective cleavage of amide bonds via mild synthetic chemistry routes poses a critical challenge. Here, we report a novel amide bond-cleavage reaction triggered by Na[AuCl4] in mild aqueous conditions, where a crucial cyclization step leads to the formation of a 5-membered ring intermediate that rapidly hydrolyses to release the free amine in high yields. Notably, the reaction exhibits remarkable site-specificity to cleave peptide bonds at the C-terminus of allyl-glycine. The strategic introduction of a leaving group at the allyl position facilitated a dual-release approach through π-acid catalyzed substitution. This reaction was employed for the targeted release of the cytotoxic drug monomethyl auristatin E in combination with an antibody-drug conjugate in cancer cells. Finally, Au-mediated prodrug activation was shown in a colorectal zebrafish xenograft model, leading to a significant increase in apoptosis and tumor shrinkage. Our findings reveal a novel metal-based cleavable reaction expanding the utility of Au complexes beyond catalysis to encompass bond-cleavage reactions for cancer therapy.

Icaritin Exerts Anti-Cancer Effects through Modulating Pyroptosis and Immune Activities in Hepatocellular Carcinoma

Icaritin (ICT), a natural compound extracted from the dried leaves of the genus Epimedium, possesses antitumor and immunomodulatory properties. However, the mechanisms through which ICT modulates pyroptosis and immune response in hepatocellular carcinoma (HCC) remain unclear. This study demonstrated that ICT exhibits pyroptosis-inducing and anti-hepatocarcinoma effects. Specifically, the caspase1-GSDMD and caspase3-GSDME pathways were found to be involved in ICT-triggered pyroptosis. Furthermore, ICT promoted pyroptosis in co-cultivation of HepG2 cells and macrophages, regulating the release of inflammatory cytokines and the transformation of macrophages into a proinflammatory phenotype. In the Hepa1-6+Luc liver cancer model, ICT treatment significantly increased the expression of cleaved-caspase1, cleaved-caspase3, and granzyme B, modulated cytokine secretion, and stimulated CD8+ T cell infiltration, resulting in a reduction in tumor growth. In conclusion, the findings in this research suggested that ICT may modulate cell pyroptosis in HCC and subsequently regulate the immune microenvironment of the tumor. These observations may expand the understanding of the pharmacological mechanism of ICT, as well as the therapy of liver cancer.

GSDMD is associated with survival in human breast cancer but does not impact anti-tumor immunity in a mouse breast cancer model

Inflammation plays a pivotal role in cancer development, with chronic inflammation promoting tumor progression and treatment resistance, whereas acute inflammatory responses contribute to protective anti-tumor immunity. Gasdermin D (GSDMD) mediates the release of pro-inflammatory cytokines such as IL-1β. While the release of IL-1β is directly linked to the progression of several types of cancers, the role of GSDMD in cancer is less clear. In this study, we show that GSDMD expression is upregulated in human breast, kidney, liver, and prostate cancer. Higher GSDMD expression correlated with increased survival in primary breast invasive carcinoma (BRCA), but not in liver hepatocellular carcinoma (LIHC). In BRCA, but not in LIHC, high GSDMD expression correlated with a myeloid cell signature associated with improved prognosis. To further investigate the role of GSDMD in anticancer immunity, we induced breast cancer and hepatoma tumors in GSDMD-deficient mice. Contrary to our expectations, GSDMD deficiency had no effect on tumor growth, immune cell infiltration, or cytokine expression in the tumor microenvironment, except for Cxcl10 upregulation in hepatoma tumors. In vitro and in vivo innate immune activation with TLR ligands, that prime inflammatory responses, revealed no significant difference between GSDMD-deficient and wild-type mice. These results suggest that the impact of GSDMD on anticancer immunity is dependent on the tumor type. They underscore the complex role of inflammatory pathways in cancer, emphasizing the need for further exploration into the multifaceted effects of GSDMD in various tumor microenvironments. As several pharmacological modulators of GSDMD are available, this may lead to novel strategies for combination therapy in cancer.

Lung-specific supramolecular nanoparticles for efficient delivery of therapeutic proteins and genome editing nucleases

Protein therapeutics play a critical role in treating a large variety of diseases, ranging from infections to genetic disorders. However, their delivery to target tissues beyond the liver, such as the lungs, remains a great challenge. Here, we report a universally applicable strategy for lung-targeted protein delivery by engineering Lung-Specific Supramolecular Nanoparticles (LSNPs). These nanoparticles are designed through the hierarchical self-assembly of metal-organic polyhedra (MOP), featuring a customized surface chemistry that enables protein encapsulation and specific lung affinity after intravenous administration. Our design of LSNPs not only addresses the hurdles of cell membrane impermeability of protein and nonspecific tissue distribution of protein delivery, but also shows exceptional versatility in delivering various proteins, including those vital for anti-inflammatory and CRISPR-based genome editing to the lung, and across multiple animal species, including mice, rabbits, and dogs. Notably, the delivery of antimicrobial proteins using LSNPs effectively alleviates acute bacterial pneumonia, demonstrating a significant therapeutic potential. Our strategy not only surmounts the obstacles of tissue-specific protein delivery but also paves the way for targeted treatments in genetic disorders and combating antibiotic resistance, offering a versatile solution for precision protein therapy.

Pyroptosis and the fight against lung cancer

Pyroptosis, a newly characterized type of inflammatory programmed cell death (PCD), is usually triggered by multiple inflammasomes which can recognize different danger or damage-associated molecular patterns (DAMPs), leading to the activation of caspase-1 and the cleavage of gasdermin D (GSDMD). Gasdermin family pore-forming proteins are the executers of pyroptosis and are normally maintained in an inactive state through auto-inhibition. Upon caspases mediated cleavage of gasdermins, the pro-pyroptotic N-terminal fragment is released from the auto-inhibition of C-terminal fragment and oligomerizes, forming pores in the plasma membrane. This results in the secretion of interleukin (IL)-1β, IL-18, and high-mobility group box 1 (HMGB1), generating osmotic swelling and lysis. Current therapeutic approaches including chemotherapy, radiotherapy, molecularly targeted therapy and immunotherapy for lung cancer treatment efficiently force the cancer cells to undergo pyroptosis, which then generates local and systemic antitumor immunity. Thus, pyroptosis is recognized as a new therapeutic regimen for the treatment of lung cancer. In this review, we briefly describe the signaling pathways involved in pyroptosis, and endeavor to discuss the antitumor effects of pyroptosis and its potential application in lung cancer therapy, focusing on the contribution of pyroptosis to microenvironmental reprogramming and evocation of antitumor immune response.

Targeting novel regulated cell death: Ferroptosis, pyroptosis and necroptosis in anti-PD-1/PD-L1 cancer immunotherapy

Chemotherapy, radiotherapy, and immunotherapy represent key tumour treatment strategies. Notably, immune checkpoint inhibitors (ICIs), particularly anti-programmed cell death 1 (PD1) and anti-programmed cell death ligand 1 (PD-L1), have shown clinical efficacy in clinical tumour immunotherapy. However, the limited effectiveness of ICIs is evident due to many cancers exhibiting poor responses to this treatment. An emerging avenue involves triggering non-apoptotic regulated cell death (RCD), a significant mechanism driving cancer cell death in diverse cancer treatments. Recent research demonstrates that combining RCD inducers with ICIs significantly enhances their antitumor efficacy across various cancer types. The use of anti-PD-1/PD-L1 immunotherapy activates CD8+ T cells, prompting the initiation of novel RCD forms, such as ferroptosis, pyroptosis, and necroptosis. However, the functions and mechanisms of non-apoptotic RCD in anti-PD1/PD-L1 therapy remain insufficiently explored. This review summarises the emerging roles of ferroptosis, pyroptosis, and necroptosis in anti-PD1/PD-L1 immunotherapy. It emphasises the synergy between nanomaterials and PD-1/PD-L1 inhibitors to induce non-apoptotic RCD in different cancer types. Furthermore, targeting cell death signalling pathways in combination with anti-PD1/PD-L1 therapies holds promise as a prospective immunotherapy strategy for tumour treatment.

Molecular probes for monitoring pyroptosis: design, imaging and theranostic application

Pyroptosis is a recently discovered process of programmed cell death that is linked with tumor progression and potential treatment strategies. Unlike other forms of programmed cell death, such as apoptosis or necrosis, pyroptosis is associated with pore-forming proteins gasdermin D (GSDMD), which are cleaved by caspase enzymes to form oligomers. These oligomers are then inserted into the cell surface membrane, causing pores to consequently result in rapid cell death. Pyroptosis, in conjunction with immunotherapy, represents a promising avenue for prognostication and antitumor therapy, providing a more precise direction for disease treatment. To gain deeper insight into the mechanisms underlying pyroptosis in real-time, non-invasive and live cell imaging techniques are urgently needed. Non-invasive imaging techniques can enhance future diagnostic and therapeutic approaches for inflammatory diseases, including different types of tumors. This review article discusses various non-invasive molecular probes for detecting pyroptosis, including genetic reporters and nanomaterials. These strategies can enhance scientists' understanding of pyroptosis and help discover personalized and effective ways to treat inflammatory diseases, particularly tumors.

Targeting ROS in cancer: rationale and strategies

Reactive oxygen species (ROS) in biological systems are transient but essential molecules that are generated and eliminated by a complex set of delicately balanced molecular machineries. Disruption of redox homeostasis has been associated with various human diseases, especially cancer, in which increased ROS levels are thought to have a major role in tumour development and progression. As such, modulation of cellular redox status by targeting ROS and their regulatory machineries is considered a promising therapeutic strategy for cancer treatment. Recently, there has been major progress in this field, including the discovery of novel redox signalling pathways that affect the metabolism of tumour cells as well as immune cells in the tumour microenvironment, and the intriguing ROS regulation of biomolecular phase separation. Progress has also been made in exploring redox regulation in cancer stem cells, the role of ROS in determining cell fate and new anticancer agents that target ROS. This Review discusses these research developments and their implications for cancer therapy and drug discovery, as well as emerging concepts, paradoxes and future perspectives.

Radiotherapy activates picolinium prodrugs in tumours

Radiotherapy-induced prodrug activation provides an ideal solution to reduce the systemic toxicity of chemotherapy in cancer therapy, but the scope of the radiation-activated protecting groups is limited. Here we present that the well-established photoinduced electron transfer chemistry may pave the way for developing versatile radiation-removable protecting groups. Using a functional reporter assay, N-alkyl-4-picolinium (NAP) was identified as a caging group that efficiently responds to radiation by releasing a client molecule. When evaluated in a competition experiment, the NAP moiety is more efficient than other radiation-removable protecting groups discovered so far. Leveraging this property, we developed a NAP-derived carbamate linker that releases fluorophores and toxins on radiation, which we incorporated into antibody-drug conjugates (ADCs). These designed ADCs were active in living cells and tumour-bearing mice, highlighting the potential to use such a radiation-removable protecting group for the development of next-generation ADCs with improved stability and therapeutic effects.

Enhanced pyroptosis induction with pore-forming gene delivery for osteosarcoma microenvironment reshaping

Osteosarcoma is the most common malignant bone tumor without efficient management for improving 5-year event-free survival. Immunotherapy is also limited due to its highly immunosuppressive tumor microenvironment (TME). Pore-forming gasdermins (GSDMs)-mediated pyroptosis has gained increasing concern in reshaping TME, however, the expressions and relationships of GSDMs with osteosarcoma remain unclear. Herein, gasdermin E (GSDME) expression is found to be positively correlated with the prognosis and immune infiltration of osteosarcoma patients, and low GSDME expression was observed. A vector termed as LPAD contains abundant hydroxyl groups for hydrating layer formation was then prepared to deliver the GSDME gene to upregulate protein expression in osteosarcoma for efficient TME reshaping via enhanced pyroptosis induction. Atomistic molecular dynamics simulations analysis proved that the hydroxyl groups increased LPAD hydration abilities by enhancing coulombic interaction. The upregulated GSDME expression together with cleaved caspase-3 provided impressive pyroptosis induction. The pyroptosis further initiated proinflammatory cytokines release, increased immune cell infiltration, activated adaptive immune responses and create a favorable immunogenic hot TME. The study not only confirms the role of GSDME in the immune infiltration and prognosis of osteosarcoma, but also provides a promising strategy for the inhibition of osteosarcoma by pore-forming GSDME gene delivery induced enhanced pyroptosis to reshape the TME of osteosarcoma.

In situ bioorthogonal-modulation of m6A RNA methylation in macrophages for efficient eradication of intracellular bacteria

N6-Methyladenosine (m6A) methylation plays a critical role in controlling the RNA fate. Emerging evidence has demonstrated that aberrant m6A methylation in immune cells such as macrophages could alter cell homeostasis and function, which can be a promising target for disease treatment. Despite tremendous progress in regulating the level of m6A methylation, the current methods suffer from the time-consuming operation and annoying off-target effect, which hampers the in situ manipulation of m6A methylation. Here, a bioorthogonal in situ modulation strategy of m6A methylation was proposed. Well-designed covalent organic framework (COF) dots (CIDM) could deprotect the agonist prodrug of m6A methyltransferase, resulting in a considerable hypermethylation of m6A modification. Simultaneously, the bioorthogonal catalyst CIDM showed oxidase (OXD)-mimic activity that further promoted the level of m6A methylation. Ultimately, the potential therapeutic effect of bioorthogonal controllable regulation of m6A methylation was demonstrated through intracellular bacteria eradication. The remarkable antimicrobial outcomes indicate that upregulating m6A methylation in macrophages could reprogram them into the M1 phenotype with high bactericidal activity. We believe that our bioorthogonal chemistry-controlled epigenetics regulatory strategy will provide a unique insight into the development of controllable m6A methylation.

Mitoxantrone Combined with Engineered TRAIL-Nanovesicles for Enhanced Cancer Immunotherapy Via Converting Apoptosis into Pyroptosis

Pyroptosis, a highly inflammatory form of programmed cell death, has emerged as a promising target for cancer immunotherapy. However, in the context of pyroptosis execution, while both caspase-3 and GSDME are essential, it is noteworthy that GSDME is frequently under-expressed in cold tumors. To overcome this limitation, engineered cellular nanovesicles (NVs) presenting TRAIL on their membranes (NVTRAIL) are developed to trigger the upregulation of cleaved caspase-3. When strategically combined with the chemotherapeutic agent mitoxantrone (MTO), known for its ability to enhance GSDME expression, MTO@NVTRAIL can convert cancer cells from apoptosis into pyroptosis, inhibit the tumor growth and metastasis successfully in primary tumor. The microparticles released by pyroptotic tumor cells also exhibited certain cytotoxicity against other tumor cells. In addition, tumor cells exposed to the combination treatment of MTO@NVTRAIL in vitro have also demonstrated potential utility as a novel form of vaccine for cancer immunotherapy. Flow analysis of the tumor microenvironment and draining lymph nodes reveals an increased proportion of matured dendritic cells and activation of T cells. In summary, the research provided a reference and alternative approach to induce cancer pyroptosis for clinical antitumor therapy based on engineered cellular nanovesicles and chemotherapy.

The Role and Therapeutic Potential of Pyroptosis in Colorectal Cancer: A Review

Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality worldwide. The unlimited proliferation of tumor cells is one of the key features resulting in the malignant development and progression of CRC. Consequently, understanding the potential proliferation and growth molecular mechanisms and developing effective therapeutic strategies have become key in CRC treatment. Pyroptosis is an emerging type of regulated cell death (RCD) that has a significant role in cells proliferation and growth. For the last few years, numerous studies have indicated a close correlation between pyroptosis and the occurrence, progression, and treatment of many malignancies, including CRC. The development of effective therapeutic strategies to inhibit tumor growth and proliferation has become a key area in CRC treatment. Thus, this review mainly summarized the different pyroptosis pathways and mechanisms, the anti-tumor (tumor suppressor) and protective roles of pyroptosis in CRC, and the clinical and prognostic value of pyroptosis in CRC, which may contribute to exploring new therapeutic strategies for CRC.

Radiotherapy-triggered reduction of platinum-based chemotherapeutic prodrugs in tumours

Pt(II) drugs are a widely used chemotherapeutic, yet their side effects can be severe. Here we show that the radiation-induced reduction of Pt(IV) complexes to cytotoxic Pt(II) drugs is rapid, efficient and applicable in water, that it is mediated by hydrated electrons from water radiolysis and that the X-ray-induced release of Pt(II) drugs from an oxaliplatin prodrug in tumours inhibits their growth, as we show with nearly complete tumour regression in mice with subcutaneous human tumour xenografts. The combination of low-dose radiotherapy with a Pt(IV)-based antibody-trastuzumab conjugate led to the tumour-selective release of the chemotherapeutic in mice and to substantial therapeutic benefits. The radiation-induced local reduction of platinum prodrugs in the reductive tumour microenvironment may expand the utility of radiotherapy.

A Cascade-Amplified Pyroptosis Inducer: Optimizing Oxidative Stress Microenvironment by Self-Supplying Reactive Nitrogen Species Enables Potent Cancer Immunotherapy

Selective generation of sufficient pyroptosis inducers at the tumor site without external stimulation holds immense significance for a longer duration of immunotherapy. Here, we report a cascade-amplified pyroptosis inducer CSCCPT/SNAP that utilizes reactive nitrogen species (RNS), self-supplied from the diffusion-controlled reaction between reactive oxygen species (ROS) and nitric oxide (NO) to potentiate pyroptosis and immunotherapy, while both endogenous mitochondrial ROS stimulated by released camptothecin and released NO initiate pyroptosis. Mechanistically, cascade amplification of the antitumor immune response is prompted by the cooperation of ROS and NO and enhanced by RNS with a long lifetime, which could be used as a pyroptosis trigger to effectively compensate for the inherent drawbacks of ROS, resulting in long-lasting pyroptosis for favoring immunotherapy. Tumor growth is efficiently inhibited in mouse melanoma tumors through the facilitation of reactive oxygen/nitrogen species (RONS)-NO synergy. In summary, our therapeutic approach utilizes supramolecular engineering and nanotechnology to integrate ROS producers and NO donors of tumor-specific stimulus responses into a system that guarantees synchronous generation of these two reactive species to elicit pyroptosis-evoked immune response, while using self-supplied RNS as a pyroptosis amplifier. RONS-NO synergy achieves enhanced and sustained pyroptosis and antitumor immune responses for robust cancer immunotherapy.

Imaging and Downstaging Bladder Cancer with the 177Lu-Labeled Bioorthogonal Nanoprobe

Efforts on bladder cancer treatment have been shifting from extensive surgery to organ preservation in the past decade. To this end, we herein develop a multifunctional nanoagent for bladder cancer downstaging and bladder-preserving therapy by integrating mucosa penetration, reduced off-target effects, and internal irradiation therapy into a nanodrug. Specifically, an iron oxide nanoparticle was used as a carrier that was coated with hyaluronic acid (HA) for facilitating mucosa penetration. Dibenzocyclooctyne (DBCO) was introduced into the HA coating layer to react through bioorthogonal reaction with azide as an artificial receptor of bladder cancer cells, to improve the cellular internalization of the nanoprobe labeled with 177Lu. Through magnetic resonance imaging, the targeted imaging of both nonmuscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC) was realized after intravesical instillation of the multifunctional probe, both NMIBC and MIBC were found downstaged, and the metastasis was inhibited, which demonstrates the potential of the multifunctional nanoprobe for bladder preservation in bladder cancer treatment.

Visualizing the crucial roles of plasma membrane and peroxynitrite during abdominal aortic aneurysm using two-photon fluorescence imaging

Peroxynitrite (ONOO-) and cell plasma membrane (CPM) are two key factors in cell pyroptosis during the progression of abdominal aortic aneurysm (AAA). However, their combined temporal and spatial roles in initiating AAA pathogenesis remain unclear. Herein, we developed a two-photon fluorescence probe, BH-Vis, enabling real-time dynamic detection of CPM and ONOO- changes, and revealing their interplay in AAA. BH-Vis precisely targets CPM with reduced red fluorescence intensity correlating with diminished CPM tension. Concurrently, a blue shift of the fluorescence signal of BH-Vis occurs in response to ONOO- offering a reliable ratiometric detection mode with enhanced accuracy by minimizing external testing variables. More importantly, two photon confocal imaging with palmitic acid (PA) and ganglioside (GM1) manipulation, which modulating cell pyroptosis, showcases reliable fluorescence fluctuations. This groundbreaking application of BH-Vis in a mouse AAA model demonstrates its significant potential for accurately identifying cell pyroptosis levels during AAA development.

A General Molecular Structural Design for Highly Efficient Photopyroptosis that can be Activated within 10 s Irradiation

Photopyroptosis is an emerging research branch of photodynamic therapy (PDT), whereas there remains a lack of molecular structural principles to fabricate photosensitizers for triggering a highly efficient pyroptosis. Herein, a general and rational structural design principle to implement this hypothesis, is proposed. The principle relies on the clamping of cationic moieties (e.g., pyridinium, imidazolium) onto one photosensitive core to facilitate a considerable mitochondrial targeting (both of the inner and the outer membranes) of the molecules, thus maximizing the photogenerated reactive oxygen species (ROS) at the specific site to trigger the gasdermin E-mediated pyroptosis. Through this design, the pyroptotic trigger can be achieved in a minimum of 10 s of irradiation with a substantially low light dosage (0.4 J cm⁻2), compared to relevant work reported (up to 60 J cm⁻2). Moreover, immunotherapy with high tumor inhibition efficiency is realized by applying the synthetic molecules alone. This structural paradigm is valuable for deepening the understanding of PDT (especially the mitochondrial-targeted PDT) from the perspective of pyroptosis, toward the future development of the state-of-the-art form of PDT.

Hyperactivation of SREBP induces pannexin-1-dependent lytic cell death

Sterol-regulatory element binding proteins (SREBPs) are a conserved transcription factor family governing lipid metabolism. When cellular cholesterol level is low, SREBP2 is transported from the endoplasmic reticulum to the Golgi apparatus where it undergoes proteolytic activation to generate a soluble N-terminal fragment, which drives the expression of lipid biosynthetic genes. Malfunctional SREBP activation is associated with various metabolic abnormalities. In this study, we find that overexpression of the active nuclear form SREBP2 (nSREBP2) causes caspase-dependent lytic cell death in various types of cells. These cells display typical pyroptotic and necrotic signatures, including plasma membrane ballooning and release of cellular contents. However, this phenotype is independent of the gasdermin family proteins or mixed lineage kinase domain-like (MLKL). Transcriptomic analysis identifies that nSREBP2 induces expression of p73, which further activates caspases. Through whole-genome CRISPR-Cas9 screening, we find that Pannexin-1 (PANX1) acts downstream of caspases to promote membrane rupture. Caspase-3 or 7 cleaves PANX1 at the C-terminal tail and increases permeability. Inhibition of the pore-forming activity of PANX1 alleviates lytic cell death. PANX1 can mediate gasdermins and MLKL-independent cell lysis during TNF-induced or chemotherapeutic reagents (doxorubicin or cisplatin)-induced cell death. Together, this study uncovers a noncanonical function of SREBPs as a potentiator of programmed cell death and suggests that PANX1 can directly promote lytic cell death independent of gasdermins and MLKL.