cGAS-STING drives the IL-6-dependent survival of chromosomally instable cancers

Porcine cGAS-STING signalling induced apoptosis negatively regulates STING downstream IFN response and autophagy via different mechanisms

The innate immune cGAS-STING signalling pathway recognizes double-stranded DNA and induces the interferon (IFN) response, autophagy and apoptosis, exerting a broad antiviral effect. However, the mechanisms and interrelationship between STING induced downstream IFN, autophagy, and apoptosis in livestock have not been fully elucidated. Our previous study defined porcine STING (pSTING) induced IFN, autophagy and apoptosis, and showed that IFN does not affect autophagy and apoptosis, whereas autophagy inhibits both IFN and apoptosis, likely by promoting pSTING degradation. In this study, we further explored the underlying mechanism of pSTING induced apoptosis and the regulation of IFN and autophagy by apoptosis. First, pSTING induces endoplasmic reticulum (ER) stress and mitochondrial damage to activate caspases 9, 3, and 7, which drive intrinsic apoptosis. Second, pSTING triggered apoptosis inhibits the IFN response by activating caspase 7, which cleaves pIRF3 at the species specific D197/D198 site. Third, pSTING activated apoptotic caspases 9, 3, and 7 reduce the expression of ATG proteins, and cleave the ATG5-ATG12L1 complex, effectively inhibiting autophagy. Fourth, knockout of pSTING activated apoptosis heightens the IFN response and autophagy, while suppressing the replication of Herpes Simplex Virus type 1 (HSV-1), Vesicular Stomatitis Virus (VSV) and Pseudorabies Virus (PRV). This study sheds light on the molecular mechanisms of innate immunity in pigs.

Pushing the boundaries of radiotherapy-immunotherapy combinations: highlights from the 7th immunorad conference

Over the last decade, the annual Immunorad Conference, held under the joint auspicies of Gustave Roussy (Villejuif, France) and the Weill Cornell Medical College (New-York, USA) has aimed at exploring the latest advancements in the fields of tumor immunology and radiotherapy-immunotherapy combinations for the treatment of cancer. Gathering medical oncologists, radiation oncologists, physicians and researchers with esteemed expertise in these fields, the Immunorad Conference bridges the gap between preclinical outcomes and clinical opportunities. Thus, it paves a promising way toward optimizing radiotherapy-immunotherapy combinations and, from a broader perspective, improving therapeutic strategies for patients with cancer. Herein, we report on the topics developed by key-opinion leaders during the 7th Immunorad Conference held in Paris-Les Cordeliers (France) from September 27th to 29th 2023, and set the stage for the 8th edition of Immunorad which will be held at Weill Cornell Medical College (New-York, USA) in October 2024.

A self-accelerating 'copper bomb' strategy activated innate and adaptive immune response against triple-negative breast cancer

Triple-negative breast cancer (TNBC) presents therapeutic challenges due to its aggressive, drug-resistance, and low immunological reactivity. Cuproptosis, an emerging therapeutic modality, is a promising strategic intervention for treating TNBC. Nonetheless, the effectiveness of cuproptosis is compromised by tumor adaptations, including the Warburg effect, increased intracellular glutathione (GSH), and copper efflux, thus breaking the barrier of cuproptosis is the basis for developing cuproptosis-based clinical therapies. Herein, a self-accelerating strategy utilizing a pH-responsive copper framework encapsulating glucose oxidase (GOx), modified with polyethylene glycol (PEG) and tumor-penetrating peptide (tLyp1) has been developed. Upon reaching the acidic tumor microenvironment, the released GOx increases intracellular acidity and hydrogen peroxide (H2O2). The elevated intracellular GSH and H2O2 serve as "fuel" to amplify the copper-based catalytic within tumor cells. Concurrently, the reduction of copper efflux proteins (ATP7B) and the depletion of GSH lead to copper overload in tumor cells, leading to cuproptosis via copper overload, mitochondrial disruption, and Fe-S protein instability. This constellation of interrelated events constitutes a potent "Copper Bomb," which concurrently triggers the immune system and effectively kills the tumor. It robustly engages innate and adaptive immunity via the release of mitochondrial DNA, facilitating the cGAS-STING pathway and precipitating immunogenic cell death. This process reverses the immunosuppressive tumor microenvironment, eliminates tumor cells, and suppresses metastasis, thus offering a novel therapeutic modality for the comprehensive treatment of triple-negative breast cancer (TNBC).

Ultrasound-induced mechanical damage of cancer cell cytoskeleton causes disruption of nuclear envelope and activation of cGAS-STING

Neoplastic transformation is accompanied by critical changes in cell mechanical properties, including reduced cell elasticity. By leveraging such mechanical flaw, exposure to low intensity therapeutic ultrasounds (LITUS) has been proposed as a tool for selective killing of cancer cells. Here, we have developed dynamic models to address the morpho-mechanical differences between prostate cancer and non-tumoral counterparts and studied the effects of LITUS on cell viability. We show that LITUS exposure (1 MHz) leads to cancer-selective cytoskeletal disruption associated to loss of nuclear envelope integrity, DNA damage marked by γH2AX and 53BP1 foci, and release of DNA into the cytosol with activation of the cGAS-STING signaling cascade. Mechanistically, the LINC complex, which connects the cytoskeleton to nucleoskeleton and chromosomes, is critical to mediate nuclear rupture triggered by LITUS. Accordingly, genetic ablation of the LINC component SUN2 tuned down DNA damage and cGAS-STING signaling while the inactivation of the endosomal sorting complex (ESCRT), required for the transport machinery that preserves the nuclear envelope integrity, enhanced cell killing by LITUS. In conclusion, LITUS induce cancer cell DNA damage and an innate immune response, this suggesting LITUS treatment as a mechanobiology-driven anti-neoplastic strategy.

cGAS/STING-Independent Induction of Type I Interferon by Inhibitors of the Histone Methylase KDM5B

Studies support the role of hexamethylene bis-acetamide [HMBA] induced protein 1 (HEXIM1) as a tumor suppressor. We previously reported that the histone demethylase, KDM5B, inhibits the expression of HEXIM1, and KDM5B inhibitors (KDM5Bi) upregulate HEXIM1 expression. As a consequence, KDM5Bi inhibited cell proliferation, induced differentiation, potentiated sensitivity to cancer chemotherapy, and inhibited breast tumor metastasis. HEXIM1 is crucial for the regulation of triple-negative breast cancer (TNBC) phenotype by KDM5Bi. Type I Interferon (IFN-I) employs the immune system in the tumor microenvironment to restrict tumor growth. Moreover, therapeutic approaches (including mainstay chemotherapy) engage IFN-I signaling. We report herein that HEXIM1 and KDM5Bi induce IFN-I in TNBC. HEXIM1 and KDM5Bi downregulate the expression of polyribonucleotide nucleotidyltransferase 1 (PNPT1) resulting in the release of mitochondrial dsRNA (mt-dsRNA) into the cytoplasm. HEXIM1 also upregulates melanoma differentiation-associated protein 5 (MDA5), a cytoplasmic viral RNA receptor in the innate immune system. MDA5 is required for HEXIM1 and KDM5Bi to induce IFN-I and downstream signaling factors. We observed the augmentation of DNA damage response to Doxorubicin in the presence of KDM5Bi, and this action is a contributing factor in KDM5Bi-induced IFN-I. These actions of HEXIM1 and KDM5Bi occur independently of Cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (cGAS/STING), a major DNA sensing pathway and inducer of innate immunity. Via the upregulation of HEXIM1, KDM5Bi represent pharmacologically induced and tumor intrinsic IFN-I production that is cGAS/STING independent. This is critical because cGAS/STING induce an inflammatory response that promotes the survival of cancer cells, and STING is often impaired in malignant cancers.

Targeting vulnerabilities of aneuploid cells for cancer therapy

Aneuploidy is a common feature of cancer that drives tumor evolution, but it also creates cellular vulnerabilities that might be exploited therapeutically. Recent advances in genomic technologies and experimental models have uncovered diverse cellular consequences of aneuploidy, revealing dependencies on mitotic regulation, DNA replication and repair, proteostasis, metabolism, and immune interactions. Harnessing aneuploidy for precision oncology requires the combination of genomic, functional, and clinical studies that will enable translation of our improved understanding of aneuploidy to targeted therapies. In this review we discuss approaches to targeting both highly aneuploid cells and cells with specific common aneuploidies, summarize the biological underpinning of these aneuploidy-induced vulnerabilities, and explore their therapeutic implications.

Single-cell chromosome and bulk transcriptome analysis as a diagnostic tool to differentiate between localized and metastatic pheochromocytoma and sympathetic paraganglioma

Approximately 10-20% of patients with pheochromocytoma or sympathetic paraganglioma (PPGL) develop metastatic disease, most often as metachronous lesions. Unfortunately, there is a lack of accurate biomarkers that can predict the biologic behavior of a PPGL at the initial diagnosis. We investigated tumor samples from patients with PPGL and a diagnosis of either localized or metastatic disease with synchronous or metachronous metastases and performed a comprehensive molecular analysis through application of single-cell whole-genome sequencing and bulk transcriptome analysis, including variant detection analysis of RNA sequences. We found that PPGL displayed complex karyotypes with recurrent aneuploidies and substantial cell-to-cell karyotype variability, indicating ongoing chromosomal instability (CIN) in both localized and metastatic tumors. Transcriptome analysis on the other hand revealed several differences between localized and metastatic PPGL including TNFα and TGFβ signaling in metastatic PPGL that were already detectable in primary tumor samples of initially non-metastatic-appearing PPGLs that developed metachronous metastases. Altogether our findings indicate that while localized and metastatic PPGL in general have comparable genomic landscapes, they do show transcriptional differences that are already detectable in primary tumor PPGL before development of metastases. This finding could provide an important tool for improvement of patient stratification at initial diagnosis.

STING Agonists and How to Reach Their Full Potential in Cancer Immunotherapy

As cancer continues to rank among the leading causes of death, the demand for novel treatments has never been higher. Immunotherapy shows promise, yet many solid tumors such as pancreatic cancer or glioblastoma remain resistant. In these, the "cold" tumor microenvironment with low immune cell infiltration and inactive anti-tumoral immune cells leads to increased tumor resistance to these drugs. This resistance has driven the development of several drug candidates, including stimulators of interferon genes (STING) agonists to reprogram the immune system to fight off tumors. Preclinical studies demonstrated that STING agonists can trigger the cancer immunity cycle and increase type I interferon secretion and T cell activation, which subsequently induces tumor regression. Despite promising preclinical data, biological and physical challenges persist in translating the success of STING agonists into clinical trials. Nonetheless, novel combination strategies are emerging, investigating the combination of these agonists with other immunotherapies, presenting encouraging preclinical results. This review will examine these potential combination strategies for STING agonists and assess the benefits and challenges of employing them in cancer immunotherapy.

Genome-wide CRISPR activation screen identifies ARL11 as a sensitivity determinant of PARP inhibitor therapy

Resistance to poly-(ADP)-ribose polymerase inhibitors (PARPi) remains a significant challenge in clinical practice, leading to treatment failure in many patients. It is crucial to better understand the molecular mechanisms that underlie PARPi resistance. In this study, utilizing a genome-wide CRISPR activation screen with olaparib, we identified ARL11 as a potential modulator of PARPi treatment response in BRCA-wild-type MDA-MB-231 cells. Mechanistically, ARL11 interacts with STING to enhance innate immunity and forms positive feedback with type I interferon (IFN) induction, which induces ARL11 up-regulation and contributes to resistance to PARPi therapy. Additionally, we observed that ARL11 interacts with the RUVBL1 and RUVBL2 (RUVBL1/2) complex, the key DNA double-strand repair proteins, facilitating DNA homologous recombination (HR) repair and significantly reducing PARPi-induced DNA double-strand damages. Clinical sample analysis reveals that the expression levels of ARL11 and RUVBL1/2 are significantly elevated in breast cancer patients compared to healthy controls. Collectively, our findings suggested that ARL11 and RUVBL1/2 may be promising therapeutic targets to sensitize breast cancer cells to PARPi therapy.

The carcinogenic metabolite acetaldehyde impairs cGAS activity to negatively regulate antiviral and antitumor immunity

The cGAS-MITA/STING pathway plays critical roles in both host defense against DNA virus and intrinsic antitumor immunity by sensing viral genomic DNA or dis-located mitochondrial/cellular DNA. Whether carcinogenic metabolites can target the cGAS-MITA axis to promote tumorigenesis is unknown. In this study, we identified acetaldehyde, a carcinogenic metabolite, as a suppressor of the cGAS-MITA pathway. Acetaldehyde inhibits the DNA virus herpes simplex virus 1 (HSV-1)- and transfected DNA-triggered but not cGAMP-induced activation of downstream components and induction of downstream effector genes. Mechanistically, acetaldehyde impairs the binding of cGAS to DNA as well as the phase separation of the cGAS-DNA complex in cells. In mouse models, acetaldehyde inhibits antiviral cytokine production, promotes viral replication and lethality upon HSV-1 infection. In a colorectal tumor xenograft model, acetaldehyde promotes tumor growth and inhibits CD8+ T cell infiltration by targeting cGAS in both the tumor cells and immune cells in mice. Bioinformatic analysis indicates that expression of acetaldehyde dehydrogenase 2 (ALDH2), which converts acetaldehyde to acetic acid, is negatively correlated with stimulatory immune signatures in clinical colorectal tumors, and higher ALDH2 expression exhibits better prognosis of colorectal cancer patients. Collectively, our results suggest that acetaldehyde impairs cGAS activity to inhibit the cGAS-MITA axis, which contributes to its effects on carcinogenesis.

MYC controls STING levels to downregulate inflammatory signaling in breast cancer cells upon DNA damage

Amplification of the MYC proto-oncogene is frequently observed in various cancer types, including triple-negative breast cancer (TNBC). Emerging evidence suggests that suppression of local antitumor immune responses by MYC, at least in part, explains the tumor-promoting effects of MYC. Specifically, MYC upregulation was demonstrated to suppress the tumor-cell intrinsic activation of a type I interferon response and thereby hamper innate inflammatory signaling, which may contribute to the disappointing response to immunotherapy in patients with TNBC. In this study, we show that MYC interferes with protein expression and functionality of the STING pathway. MYC-mediated STING downregulation in BT-549 and MDA-MB-231 TNBC cell lines requires the DNA-binding ability of MYC and is independent of binding of MYC to its co-repressor MIZ1. Both STAT1 and STAT3 promote the steady-state expression levels of STING, and STAT3 cooperates with MYC in regulating STING. Conversely, MYC-mediated downregulation of STING affects protein levels of STAT1 and downstream chemokine production. Furthermore, we show that MYC overexpression hampers immune cell activation triggered by DNA damage through etoposide or irradiation treatment and specifically impedes the activation of natural killer cells. Collectively, these results show that MYC controls STING levels and thereby regulates tumor cell-intrinsic inflammatory signaling. These results contribute to our understanding of how MYC suppresses inflammatory signaling in TNBC and may explain why a large fraction of patients with TNBC do not benefit from immunotherapy.

Cell-Autonomous Immunity: From Cytosolic Sensing to Self-Defense

As an evolutionarily conserved and ubiquitous mechanism of host defense, non-immune cells in vertebrates possess the intrinsic ability to autonomously detect and combat intracellular pathogens. This process, termed cell-autonomous immunity, is distinct from classical innate immunity. In this review, we comprehensively examine the defense mechanisms employed by non-immune cells in response to intracellular pathogen invasion. We provide a detailed analysis of the cytosolic sensors that recognize aberrant nucleic acids, lipopolysaccharide (LPS), and other pathogen-associated molecular patterns (PAMPs). Specifically, we elucidate the molecular mechanisms underlying key signaling pathways, including the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs)-mitochondrial antiviral signaling (MAVS) axis, and the guanylate-binding proteins (GBPs)-mediated pathway. Furthermore, we critically evaluate the involvement of these pathways in the pathogenesis of various diseases, including autoimmune disorders, inflammatory conditions, and malignancies, while highlighting their potential as therapeutic targets.

CDO1 phosphorylation is required for IL-6-induced tumor cell proliferation through governing cysteine availability

Inflammatory pathways are often hijacked by cancer cells to favor their own proliferation and survival. Cysteine dioxygenase type 1 (CDO1), an iron-dependent thiol dioxygenase enzyme, catalyzes the rate-limiting step for cysteine oxidation, and so that functions as an important regulator of cellular cysteine availability. However, whether inflammatory environment affects CDO1 activity and cysteine oxidation and its potential impact on tumor growth remains substantially elusive. In the present study, we demonstrate that CDO1 activity and cysteine oxidation is inhibited upon IL-6 treatment, without noticeable alterations in CDO1 expression. Mechanistically, AKT1 phosphorylates CDO1 T89 under IL-6 treatment, which represses CDO1 enzymatic activity by disrupting iron incorporation. Further, AKT1-mediated CDO1 T89 phosphorylation is required for IL-6-elicited oral squamous cell carcinoma (OSCC) growth, and is associated with the progression of OSCC development. The present data discover a new mechanism by which AKT1-mediated CDO1 T89 phosphorylation governs cysteine oxidation to support OSCC growth, thereby highlighting its value as a potential anti-tumor target.

Unveiling the crossroads of STING signaling pathway and metabolic reprogramming: the multifaceted role of the STING in the TME and new prospects in cancer therapies

The cGAS-STING signaling pathway serves as a critical link between DNA sensing and innate immunity, and has tremendous potential to improve anti-tumor immunity by generating type I interferons. However, STING agonists have shown decreasing biotherapeutic efficacy in clinical trials. Tumor metabolism, characterized by aberrant nutrient utilization and energy production, is a fundamental hallmark of tumorigenesis. And modulating metabolic pathways in tumor cells has been discovered as a therapeutic strategy for tumors. As research concerning STING progressed, emerging evidence highlights its role in metabolic reprogramming, independent its immune function, indicating metabolic targets as a strategy for STING activation in cancers. In this review, we delve into the interplay between STING and multiple metabolic pathways. We also synthesize current knowledge on the antitumor functions of STING, and the metabolic targets within the tumor microenvironment (TME) that could be exploited for STING activation. This review highlights the necessity for future research to dissect the complex metabolic interactions with STING in various cancer types, emphasizing the potential for personalized therapeutic strategies based on metabolic profiling.

CMPK2 promotes microglial activation through the cGAS-STING pathway in the neuroinflammatory mechanism

The activation of microglia and the resulting neuroinflammation play crucial regulatory roles in the pathogenesis and progression of neurological diseases, although the specific mechanisms remain incompletely understood. Cytidine monophosphate kinase 2 (CMPK2) is a key mitochondrial nucleotide kinase involved in cellular energy metabolism and nucleotide synthesis. Recent studies suggest that CMPK2 plays a role in microglial-mediated neuroinflammation; however, its specific impact on microglial activation remains unclear. In this study, we hypothesize that CMPK2 promotes microglial-mediated neuroinflammation by activating the cGAS-STING signaling pathway. To investigate this mechanism, we employed lipopolysaccharide (LPS)-treated microglial cells to investigate the detailed mechanisms by which CMPK2 regulates neuroinflammation. Our experimental results indicate that in the BV2 and mouse primary microglial neuroinflammation model, both CMPK2 protein and transcript levels were significantly elevated, accompanied by microglial activation phenotypes such as increased cell size, shortened processes, transformation to round or rod-like shapes, and elevated CD40 expression. Concurrently, there was an increase in pro-inflammatory cytokine levels and a decrease in anti-inflammatory cytokine levels. Further investigation revealed that in the microglial, the expression of cGAS and STING was elevated, along with an increase in oxidative products and inflammatory responses. CMA stimulation further intensified these changes, while cGAS knockdown mitigated them. Finally, we demonstrated that cGAS knockdown inhibited the oxidative stress, cell activation-related changes, and neuroinflammatory responses induced by CMPK2 overexpression in the BV2 neuroinflammation model. Molecular docking experiments showed that CMPK2 stably binds to cGAS at the protein level. These findings suggest that the cGAS-STING pathway mediates CMPK2-induced microglial activation. In summary, our study demonstrates that LPS-induced CMPK2 overactivity promotes microglial activation and neuroinflammatory through the cGAS-STING pathway.

The cGAS‒STING pathway in cancer immunity: mechanisms, challenges, and therapeutic implications

Innate immunity represents the body's first line of defense, effectively countering the invasion of external pathogens. Recent studies have highlighted the crucial role of innate immunity in antitumor defense, beyond its established function in protecting against external pathogen invasion. Enhancing innate immune signaling has emerged as a pivotal strategy in cancer therapy. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway is a key innate immune signal that activates the immune response and exerts antitumor effects; this is primarily attributed to the DNA receptor function of cGAS, which recognizes exogenous DNA to activate downstream STING signaling. This, in turn, promotes the activation of downstream targets such as IRF-3(Interferon Regulatory Factor 3) and NF-κB, leading to the secretion of type I interferons and proinflammatory cytokines, thereby increasing cellular immune activity. The activation of the cGAS-STING pathway may thus play a crucial role in enhancing anticancer immunity. In this paper, we reviewed the role of cGAS-STING signaling in anticancer immunity and its molecular mechanisms. Additionally, we briefly discuss the current applications of the cGAS-STING pathway in cancer immunity, summarize recent developments in STING agonists, and address the challenges facing the use of the cGAS-STING pathway in cancer therapy. Finally, we provide insights into the role of the cGAS‒STING pathway in cancer and propose new directions for cancer immunotherapy.

Chromosomal Instability and Clonal Heterogeneity in Breast Cancer: From Mechanisms to Clinical Applications

BACKGROUND

Chromosomal instability (CIN) and clonal heterogeneity (CH) are fundamental hallmarks of breast cancer that drive tumor evolution, disease progression, and therapeutic resistance. Understanding the mechanisms underlying these phenomena is essential for improving cancer diagnosis, prognosis, and treatment strategies.

METHODS

In this review, we provide a comprehensive overview of the biological processes contributing to CIN and CH, highlighting their molecular determinants and clinical relevance.

RESULTS

We discuss the latest advances in detection methods, including single-cell sequencing and other high-resolution techniques, which have enhanced our ability to characterize intratumoral heterogeneity. Additionally, we explore how CIN and CH influence treatment responses, their potential as therapeutic targets, and their role in shaping the tumor immune microenvironment, which has implications for immunotherapy effectiveness.

CONCLUSIONS

By integrating recent findings, this review underscores the impact of CIN and CH on breast cancer progression and their translational implications for precision medicine.

STING activation and overcoming the challenges associated with STING agonists using ADC (antibody-drug conjugate) and other delivery systems

In current immunotherapy cGAS (cyclic GMP-AMP synthase)-STING (stimulator of interferon genes) pathway considered as most focused area after CAR-T cell. Exploitation of host immunity against cancer using STING agonists generates the most interest as a therapeutic target. Classically cGAS activation through cytoplasmic DNA generates 2'3'cGAMP that is naturally identified STING agonist. Activation of STING leads to activation of type-1 interferon response and pro-inflammatory cytokines through TBK/IRF-3, TBK/NF-κB pathways. Pro-inflammatory cytokines attract immune cells to the tumor microenvironment and type-1 interferon exposes tumor antigens to T cells and NK cells, which leads to the activation of cellular immunity against tumor cells and eliminates tumor cells. Initially bacterial-derived c-di-AMP and c-di-GMP were identified as CDNs (Cyclic-dinucleotide) STING agonists. Moreover, chemically modified CDNs and completely synthetic STING agonists have been developed. Even though the breakthrough preclinical development none of the STING agonists were approved the by FDA for cancer therapy. All identified natural CDNs have poor pharmacokinetic properties due to high hydrophilicity and negative charge. Moreover, phosphodiester bonds in CDNs are most vulnerable to enzymatic degradation. Synthetic STING agonists have an off-target effect that generates autoimmunity and cytokine storm. STING agonist needs to improve for pharmacokinetics, efficacy, and safety. In this scenario delivery systems can overcome the challenges associated with STING agonists. Here, we highlight the ways of STING agonisms as direct and indirect, and further, we also discuss the existing STING agonists associated challenges and ongoing efforts for delivery of STING agonists in the tumor microenvironment (TME) via different non-targeted carriers like Nanoparticle, Hydrogel, Micelle, Liposome. We also discussed the most advanced targeted deliveries of ADC (Antibody-drug conjugate) and aptamers-based delivery.

A novel biosensor for the spatiotemporal analysis of STING activation during innate immune responses to dsDNA

The cGAS-STING signalling pathway has a central role in the innate immune response to extrinsic and intrinsic sources of cytoplasmic dsDNA. At the core of this pathway is cGAS-dependent production of the intra- and extra-cellular messenger cGAMP, which activates STING and leads to IRF3-dependent expression of cytokines and interferons. Despite its relevance to viral and bacterial infections, cell death, and genome instability, the lack of specific live-cell reporters has precluded spatiotemporal analyses of cGAS-STING signalling. Here, we generate a fluorescent biosensor termed SIRF (STING-IRF3), which reports on the functional interaction between activated STING and IRF3 at the Golgi. We show that cells harbouring SIRF react in a time- and concentration-dependent manner both to STING agonists and to microenvironmental cGAMP. We demonstrate that the new biosensor is suitable for single-cell characterisation of immune responses to HSV-1 infection, mtDNA release upon apoptosis, or other sources of cytoplasmic dsDNA. Furthermore, our results indicate that STING signalling is not activated by ruptured micronuclei, suggesting that other cytosolic pattern recognition receptors underlie the interferon responses to chromosomal instability.

Colorectal cancer cell-derived extracellular vesicles trigger macrophage production of IL6 through activating STING signaling to drive metastasis

Emerging evidence shows that extracellular vesicles (EVs)-mediated cargo shuttling between different kinds of cells constantly occurs in the tumor microenvironment, leading to the progression of a variety of cancers, but the biological role of DNA enriched in EVs has not been fully elucidated. Here, nuclear chromatin-originated DNA fragments were identified in human serum-derived EVs and exhibited a mild increase in the colorectal cancer patient group, unveiling their potential as a biomarker for cancer diagnosis. Molecular experiments showed that chromatin and mitochondrial DNA fragments adhered to the outer membrane of EVs were released from colorectal cancer cells and transported into macrophages where they stimulated STING signaling cascades, resulting in enhanced STAT1 phosphorylation and IL6 production. Further experiments revealed that STAT1 functioned as a potential IL6 transcription regulator through directly locating at its promoter regions to facilitate IL6 expression in macrophages. In the tumor microenvironment, the accumulated IL6 released by macrophages, in turn, provoked colorectal cancer cell epithelial to mesenchymal transition (EMT) through activating IL6R/STAT3 signaling. Our findings highlighted the importance of DNA carried by EVs in shaping the tumor environment and revealed their potential as a clinical diagnostic biomarker for colorectal cancer.

Reciprocal regulation between ferroptosis and STING-type I interferon pathway suppresses head and neck squamous cell carcinoma growth through dendritic cell maturation

Head and neck squamous cell carcinoma (HNSCC) presents a serious clinical challenge mainly due to its resistance to conventional therapies and its complex, immunosuppressive tumor microenvironment. While recent studies have identified ferroptosis as a new therapeutic option, its impact on the immune microenvironment in HNSCC remains controversial, which may hinder its translational application. Although the role of the stimulator of interferon genes (STING)-type I interferon (IFN-I) pathway in antitumor immune responses has been widely investigated, its relationship with ferroptosis in HNSCC has not been fully explored. In this study, we discovered that ferroptosis in HNSCC inhibited tumor growth, activated STING-IFN-I pathway and subsequently improved recruitment and maturation of dendritic cells. We further demonstrated that IFN-I could enhance ferroptosis by inhibiting xCT-glutathione peroxidase 4 (GPX4) antioxidant system. To harness this positive feedback loop, we treated HNSCC tumors with both ferroptosis inducer and STING agonist, resulting in significant tumor suppression, elevated ferroptosis levels and enhanced dendritic cell infiltration. Overall, our findings reveal a mutually regulatory relationship between ferroptosis and the intrinsic STING-IFN-I pathway, providing novel insights into immune-mediated tumor suppression and suggesting its potential as therapeutic approach in HNSCC.

Chromosomal Instability Is Associated with cGAS-STING Activation in EGFR-TKI Refractory Non-Small-Cell Lung Cancer

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are standard therapies for EGFR-mutated non-small-cell lung cancer (NSCLC); however, their efficacy is inconsistent. Secondary mutations in the EGFR or other genes that lead to resistance have been identified, but resistance mechanisms have not been fully identified. Chromosomal instability (CIN) is a hallmark of cancer and results in genetic diversity. In this study, we demonstrated by transcriptomic analysis that CIN activates the cGAS-STING signaling pathway, which leads to EGFR-TKI refractoriness in a subset of EGFR-mutated NSCLC patients. Furthermore, EGFR-mutated H1975dnMCAK cells, which frequently underwent chromosomal mis-segregation, demonstrated refractoriness to the EGFR-TKI osimertinib compared to control cells. Second, H1975dnMCAK cells exhibited activation of cGAS-STING signaling and its downstream signaling, including tumor-promoting cytokine IL-6. Finally, chromosomally unstable EGFR-mutated NSCLC exhibited enhanced epithelial-mesenchymal transition (EMT). Blockade of cGAS-STING-TBK1 signaling reversed EMT, resulting in restored susceptibility to EGFR-TKIs in vitro and in vivo. These results suggest that CIN may lead to the activation of cGAS-STING signaling in some EGFR-mutated NSCLC, resulting in EMT-associated EGFR-TKI resistance.

The cGAS-STING pathway in cancer immunity: dual roles, therapeutic strategies, and clinical challenges

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway is a crucial component of the host's innate immunity and plays a central role in detecting cytosolic double-stranded DNA from endogenous and exogenous sources. Upon activation, cGAS synthesizes cGAMP, which binds to STING, triggering a cascade of immune responses, including the production of type I interferons and pro-inflammatory cytokines. In the context of cancers, the cGAS-STING pathway can exert dual roles: on the one hand, it promotes anti-tumor immunity by enhancing antigen presentation, stimulating T-cell responses, and inducing direct tumor cell apoptosis. On the other hand, chronic activation, particularly in tumors with chromosomal instability, can lead to immune suppression and tumor progression. Persistent cGAS-STING signaling results in the up-regulation of immune checkpoint molecules such as PD-L1, contributing to immune evasion and metastasis. Consequently, anti-tumor strategies targeting the cGAS-STING pathway have to consider the balance of immune activation and the immune tolerance caused by chronic activation. This review explores the mechanisms underlying both the anti-tumor and protumor roles of the cGAS-STING pathway, with a focus on potential therapeutic approaches, and the challenges faced in their clinical application, along with corresponding solutions.

Inhibition of the STAT3/Fanconi anemia axis is synthetic lethal with PARP inhibition in breast cancer

The targeting of cancer stem cells (CSCs) has proven to be an effective approach for limiting tumor progression, thus necessitating the identification of new drugs with anti-CSC activity. Through a high-throughput drug repositioning screen, we identify the antibiotic Nifuroxazide (NIF) as a potent anti-CSC compound. Utilizing a click chemistry strategy, we demonstrate that NIF is a prodrug that is specifically bioactivated in breast CSCs. Mechanistically, NIF-induced CSC death is a result of a synergistic action that combines the generation of DNA interstrand crosslinks with the inhibition of the Fanconi anemia (FA) pathway activity. NIF treatment mimics FA-deficiency through the inhibition of STAT3, which we identify as a non-canonical transcription factor of FA-related genes. NIF induces a chemical HRDness (Homologous Recombination Deficiency) in CSCs that (re)sensitizes breast cancers with innate or acquired resistance to PARP inhibitor (PARPi) in patient-derived xenograft models. Our results suggest that NIF may be useful in combination with PARPi for the treatment of breast tumors, regardless of their HRD status.

PRODE recovers essential and context-essential genes through neighborhood-informed scores

Gene context-essentiality assessment supports precision oncology opportunities. The variability of gene effects inference from loss-of-function screenings across models and technologies limits identifying robust hits. We propose a computational framework named PRODE that integrates gene effects with protein-protein interactions to generate neighborhood-informed essential (NIE) and neighborhood-informed context essential (NICE) scores. It outperforms the canonical gene effect approach in recovering missed essential genes in shRNA screens and prioritizing context-essential hits from CRISPR-KO screens, as supported by in vitro validations. Applied to Her2 + breast cancer tumor samples, PRODE identifies oxidative phosphorylation genes as vulnerabilities with prognostic value, highlighting new therapeutic opportunities.

Application of nanoparticles with activating STING pathway function in tumor synergistic therapy

Although immunotherapy is currently one of the most promising methods for cancer treatment, its clinical application is limited due to issues such as excessive autoimmune responses and lack of specificity. Therefore, there is a need to improve immunotherapy by integrating emerging medical technologies with traditional treatments. The activation of the cGAS-STING pathway plays a crucial role in innate immunity and antiviral defense, making it highly promising for immunotherapy and attracting significant attention. In recent years, research on nanomaterials and immunotherapy has achieved groundbreaking progress in the medical field. Due to their unique size, shape, stiffness, surface effects, and quantum size effects, nanomaterials can either carry STING activators or directly activate the STING pathway, offering new opportunities for tumor-specific immunotherapy. These unique advantages of nanomaterials have opened up broader prospects for nanoparticle-based therapies targeting the STING pathway. This paper summarizes the current research on utilizing nanomaterials to activate the STING pathway, detailing the characteristics, classifications, and different approaches for targeting tumor cells. Additionally, it focuses on the latest advancements in combined nanotherapies based on cGAS-STING pathway activation, including the integration of nanomaterial-mediated STING pathway activation with immunotherapy, radiotherapy, chemotherapy, targeted therapy, and photodynamic therapy. This provides new ideas for nanoparticle-based combination therapies involving the STING pathway.

Predictive value of serum cytokines in patients with non-small-cell lung cancer receiving anti-PD-1 blockade therapy: a meta-analysis

Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related deaths worldwide. Immunotherapy, particularly PD-1 inhibitors, has revolutionized the treatment landscape for NSCLC. However, the predictive biomarkers for PD-1 inhibitor therapy are still limited. Serum cytokines have emerged as potential biomarkers for predicting treatment outcomes. This meta-analysis aims to investigate the predictive value of serum cytokines in PD-1 inhibitor therapy for NSCLC. We conducted a comprehensive literature search in major databases, including PubMed, Google scholar, Embase, and Cochrane database, with a focus on literature published up until October 22, 2024. Studies investigating the association between serum cytokine levels and treatment outcomes in NSCLC patients receiving PD-1 inhibitor therapy were included. The primary outcomes were progression-free survival (PFS) and overall survival (OS). The meta-analysis revealed that elevated IL-6 levels were significantly associated with poorer PFS in NSCLC patients (HR = 2.30, 95% CI [1.39-3.80], P = 0.001). Additionally, high IL-10 expression was related to poorer PFS in NSCLC after therapy (HR = 2.45, 95% CI [1.26-4.76], P = 0.009). In contrast, no significant associations were found between OS and the expression of various cytokines, including IL-4, IL-5, IL-6, IL-8, IL-10, IFN-γ, IL-1β, TNF-α, and IL-12p70. This meta-analysis demonstrates that elevated IL-6 and IL-10 levels are significantly associated with poorer PFS in NSCLC patients receiving PD-1 inhibitor therapy. These findings suggest that serum cytokine levels may serve as predictive biomarkers for treatment outcomes. Further studies are needed to validate these results and explore the underlying mechanisms.

Nanocarrier-mediated modulation of cGAS-STING signaling pathway to disrupt tumor microenvironment

The cGAS-STING signaling plays an important role in the immune response in a tumor microenvironment (TME) of triple-negative breast cancer (TNBC). The acute and controlled activation of cGAS-STING signaling results in tumor suppression, while chronic activation of cGAS-STING signaling results in immune-suppressive TME that could result in tumor survival. There is a need, therefore, to develop therapeutic strategies for harnessing tumor suppressive effects of cGAS-STING signaling while minimizing the risks associated with chronic activation. Combination therapies and nanocarriers-based delivery of cGAS-STING agonists have emerged as promising strategies in immunotherapy for controlled modulation of cGAS-STING signaling in cancer. These approaches aim to optimize the tumor suppressive effects of the cGAS-STING pathway while minimizing the challenges associated with modulators of cGAS-STING signaling. In the present review, we discuss recent advancements and strategies in combination therapies and nanocarrier-based delivery systems for effectively controlling cGAS-STING signaling in cancer immunotherapy. Further, we emphasized the significance of nanocarrier-based approaches for effective targeting of the cGAS-STING signaling, tackling resistance mechanisms, and overcoming key challenges like immune suppression, tumor heterogeneity, and off-target effects.

Poly (ADP-Ribose) Polymerase 1 Induces Cyclic GMP-AMP Synthase-stimulator of Interferon Genes Pathway Dysregulation to Promote Immune Escape of Colorectal Cancer Cells

Colorectal cancer (CRC) ranks third globally in cancer incidence and mortality, posing a significant human concern. Recent advancements in immunotherapy are noteworthy. This study explores immune modulation for CRC treatment. Initially targeting poly (ADP-ribose) polymerase 1 (PARP-1), a gene overexpressed in CRC tissues per The Cancer Genome Atlas, we examined its correlation with immune cell infiltration using the Tumor Immune Estimation Resource tool. Quantitative reverse transcription polymerase chain reaction assessed PARP-1 mRNA and inflammation-related gene expression in tumor tissues and cells. Assessing CD8 + T-cell proliferation and cytotoxicity towards HCT116 cells involved carboxyfluorescein diacetate succinimidyl ester and lactate dehydrogenase kits. Chemotaxis was gauged using a Transwell system in a CD8 + T-cell coculture setup, with immunofluorescence revealing cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) levels in HCT116 cells. Enzyme-linked immunosorbent assay kits measured CD8 + T-cell cytokine secretion. The findings suggested that PARP-1 was overexpressed in CRC tissues and cells and this overexpression was positively correlated with Treg cell infiltration. Overexpression of PARP-1 could significantly reduce the proportion of cGAS and STING-positive cells in HCT116 cells, dampen the proliferation, tumor-killing capacity, and chemotaxis of CD8 + T cells, and inhibit the secretion of related cytokines. The introduction of STING agonists could reverse the effects caused by overexpressed PARP-1. In vivo experiments affirmed the independent anti-tumor effects of PARP-1 inhibitors and STING agonists, synergistically inhibiting tumor growth. Silencing PARP-1 in HCT116 cells potentially boosts CD8 + T-cell activity against these cells through the cGAS-STING pathway.

Chromothripsis in cancer

Chromothripsis is a mutational phenomenon in which a single catastrophic event generates extensive rearrangements of one or a few chromosomes. This extreme form of genome instability has been detected in 30-50% of cancers. Studies conducted in the past few years have uncovered insights into how chromothripsis arises and deciphered some of the cellular and molecular consequences of chromosome shattering. This Review discusses the defining features of chromothripsis and describes its prevalence across different cancer types as indicated by the manifestations of chromothripsis detected in human cancer samples. The different mechanistic models of chromothripsis, derived from in vitro systems that enable causal inference through experimental manipulation, are discussed in detail. The contribution of chromothripsis to cancer development, the selective advantages that cancer cells might gain from chromothripsis, the evolutionary trajectories of chromothriptic tumours, and the potential vulnerabilities and therapeutic opportunities presented by chromothriptic cells are also highlighted.

Mechanical Force-Induced cGAS Activation in Carcinoma Cells Facilitates Splenocytes into Liver to Drive Metastasis

Liver metastasis is the main cause of cancer-related mortality. During the metastasis process, circulating carcinoma cells hardly pass through narrow capillaries, leading to nuclear deformation. However, the effects of nuclear deformation and its underlying mechanisms on metastasis need further study. Here, it is shown that mechanical force-induced nuclear deformation exacerbates liver metastasis by activating the cGAS-STING pathway, which promotes splenocyte infiltration in the liver. Mechanical force results in nuclear deformation and rupture of the nuclear envelope with inevitable DNA leakage. Cytoplasmic DNA triggers the activation of cGAS-STING pathway, enhancing the production of IL6, TNFα, and CCL2. Additionally, splenocyte recruitment by the proinflammatory cytokines support carcinoma cell survival and colonization in the liver. Importantly, both intervening activity of cGAS and blocking of splenocyte migration to the liver efficiently ameliorate liver metastasis. Overall, these findings reveal a mechanism by which mechanical force-induced nuclear deformation exacerbates liver metastasis by regulating splenocyte infiltration into the liver and support targeting cGAS and blocking splenocyte recruitment as candidate therapeutic approaches for liver metastasis.

High CDC20 levels increase sensitivity of cancer cells to MPS1 inhibitors

Spindle assembly checkpoint (SAC) inhibitors are a recently developed class of drugs, which perturb chromosome segregation during cell division, induce chromosomal instability (CIN), and eventually lead to cell death. The molecular features that determine cellular sensitivity to these drugs are not fully understood. We recently reported that aneuploid cancer cells are preferentially sensitive to SAC inhibition. Here we report that sensitivity to SAC inhibition by MPS1 inhibitors is largely driven by the expression of CDC20, a main mitotic activator of the anaphase-promoting complex (APC/C), and that the effect of CDC20 is larger than that of the APC/C itself. Mechanistically, we discovered that CDC20 depletion prolongs metaphase duration, diminishes mitotic errors, and reduces sensitivity to SAC inhibition. We found that aneuploid cells express higher basal levels of CDC20, which shortens the duration of metaphase and leads to multiple mitotic errors, resulting in increased long-term sensitivity to the additional CIN induced by SAC inhibition. Our findings propose high CDC20 expression as a molecular feature associated with the sensitivity to SAC inhibition therapy and as a potential aneuploidy-induced cellular vulnerability.

A compendium of Amplification-Related Gain Of Sensitivity genes in human cancer

While the effect of amplification-induced oncogene expression in cancer is known, the impact of copy-number gains on "bystander" genes is less understood. We create a comprehensive map of dosage compensation in cancer by integrating expression and copy number profiles from over 8000 tumors in The Cancer Genome Atlas and cell lines from the Cancer Cell Line Encyclopedia. Additionally, we analyze 17 cancer open reading frame screens to identify genes toxic to cancer cells when overexpressed. Combining these approaches, we propose a class of 'Amplification-Related Gain Of Sensitivity' (ARGOS) genes located in commonly amplified regions, yet expressed at lower levels than expected by their copy number, and toxic when overexpressed. We validate RBM14 as an ARGOS gene in lung and breast cancer cells, and suggest a toxicity mechanism involving altered DNA damage response and STING signaling. We additionally observe increased patient survival in a radiation-treated cancer cohort with RBM14 amplification.

Differential Response to Local Stimulator of Interferon Genes Agonist Administration in Tumors with Various Stimulator of Interferon Genes Statuses

Background/Objectives: The stimulator of interferon genes (STING) is currently accepted as a relevant target for anti-cancer therapies. Besides encouraging results showing STING agonist-induced tumor growth inhibition, in some types of tumors the effect is less prominent. We hypothesized that higher STING levels in cancer cells and the possibility of its activation determine a greater anti-cancer response. As the local administration of STING agonists induces a systemic reaction, we emphasized the importance of host tumor-induced hematological disruption in the efficiency of the therapeutic response. Methods: We investigated the response to STING stimulation in murine cancer cell lines-melanoma (B16-F10) and breast carcinoma (4T1)-and murine normal cell lines: fibroblast cells (NIH/3T3), endothelial cells (H5V), and macrophages (J774A.1). We assessed STING agonist-induced tumor growth inhibition and the therapy's impact on the hematological system parameters and systemic cytokine release. Results: Our results underlined the improved therapeutic effect of STING activation in melanoma (B16-F10) over breast carcinoma (4T1) tumors. The outcomes reflected a high dysregulation of the hematological system in mice with developed 4T1 tumors, which may support persistent inflammation and impede STING-induced therapeutic effects. Moreover, among typical cytokines produced following STING activation, CCL2 fold change was the one that increased the most in the serum of B16-F10-bearing mice and differentiated the observed response to the STING agonist between investigated tumor models. Conclusions: The current study provides new evidence of the different responses to STING activation among two poorly immunogenic tumor models. The high abundance of STING in B16-F10 cells and the possibility of its activation is linked with improved therapeutic response in vivo compared to 4T1. The effect also seems to be connected with a less dysregulated hematological system in mice with B16-F10 tumors over mice with 4T1 tumors. This highlighted the need for general insight into tumor-induced local and systemic responses to the efficiency of the proposed therapy.

Regulation of cGAS-STING signalling and its diversity of cellular outcomes

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signalling pathway, which recognizes both pathogen DNA and host-derived DNA, has emerged as a crucial component of the innate immune system, having important roles in antimicrobial defence, inflammatory disease, ageing, autoimmunity and cancer. Recent work suggests that the regulation of cGAS-STING signalling is complex and sophisticated. In this Review, we describe recent insights from structural studies that have helped to elucidate the molecular mechanisms of the cGAS-STING signalling cascade and we discuss how the cGAS-STING pathway is regulated by both activating and inhibitory factors. Furthermore, we summarize the newly emerging understanding of crosstalk between cGAS-STING signalling and other signalling pathways and provide examples to highlight the wide variety of cellular processes in which cGAS-STING signalling is involved, including autophagy, metabolism, ageing, inflammation and tumorigenesis.

Chromosomal instability as a driver of cancer progression

Chromosomal instability (CIN) refers to an increased propensity of cells to acquire structural and numerical chromosomal abnormalities during cell division, which contributes to tumour genetic heterogeneity. CIN has long been recognized as a hallmark of cancer, and evidence over the past decade has strongly linked CIN to tumour evolution, metastasis, immune evasion and treatment resistance. Until recently, the mechanisms by which CIN propels cancer progression have remained elusive. Beyond the generation of genomic copy number heterogeneity, recent work has unveiled additional tumour-promoting consequences of abnormal chromosome segregation. These mechanisms include complex chromosomal rearrangements, epigenetic reprogramming and the induction of cancer cell-intrinsic inflammation, emphasizing the multifaceted role of CIN in cancer.

Cladophorol-A is an inhibitor of cyclic GMP-AMP synthase

Cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) synthase (cGAS) is an enzyme sensor of double-stranded DNA (dsDNA) that serves to trigger activation of the cGAS-stimulator of interferon genes (STING) pathway. Excessive activation of this pathway has been demonstrated to contribute to various forms of inflammatory disease. As such, cGAS has arisen as a potential therapeutic target with broad potential applications. Using a pathway-targeted cell-based screening approach, we identified the natural product Cladophorol-A as a new class of non-cytotoxic cGAS inhibitor (cell-based IC50 = 370 nM). An X-ray co-crystal structure at 2.75 Å resolution revealed that Cladophorol-A inhibits cGAS by binding to its active site within the conserved adenosine nucleobase binding site.

Allosteric inhibition of the tyrosine phosphatase SHP2 enhances the anti-tumor immunity of interferon α through induction of caspase-1-mediated pyroptosis in renal cancer

Interferon alpha (IFNα) leads to therapeutic effects on various tumors, especially renal cell cancer (RCC), by directly protecting against tumors cell proliferation or indirectly inducing an anti-tumor immune response. However, new combination therapies are needed to enhance the efficacy of IFNα and reduce its adverse effects during long-term treatment. In this study, we found that the anti-proliferative effects of IFNα on RCC cells in vitro and in vivo were greater after the allosteric inhibition of SHP2 by SHP099 than after treatment with enzymatic inhibitors of SHP2. SHP099 increased IFNα-induced pro-caspase-1 expression in RCC cells, activated the NLRP3 inflammasome, and induced pyroptosis. Mechanistically, SHP099 not only increased the expression of NLRP3 inflammasome components via the NF-κB signaling pathway, but also further activated the NLRP3 inflammasome by regulating mitochondrial homeostasis through ANT1-mediated reactive oxygen species modulation. Allosteric inhibition of SHP2 by SHP099 also potently enhanced the anti-tumor immunity induced by IFNα by modulating T cell proliferation and infiltration in vitro and in vivo. These results reveal the new function of SHP2 in NLRP3 inflammasome activation and pyroptosis in RCC and provide a basis for further investigating the combination of allosteric SHP2 inhibitors with IFNα in cancer immunotherapy.

STING exerts antiviral innate immune response by activating pentose phosphate pathway

BACKGROUND

The innate immune system serves as the host's first line of defense against invading pathogens. Stimulator of interferon genes (STING) is a key component of this system, yet its relationship with glucose metabolism, particularly in antiviral immunity, remains underexplored.

METHODS

Metabolomics analysis was used for detecting metabolic alterations in spleens from STING knockout (KO) and wild-type (WT) mice. Co-immunoprecipitation was employed for determining ubiquitination of TKT. Mass spectrometry was used for detecting interaction proteins of STING. Enzyme activity kits were used for detecting the activities of TKT and G6PD.

RESULTS

In this study, we demonstrate that herpes simplex virus (HSV) infection activates the pentose phosphate pathway (PPP) in host cells, thereby initiating an antiviral immune response. Using STING-manipulated cells and systemic knockout mice, we show that STING positively regulates PPP, which, in turn, limits HSV infection. Inhibition of the PPP significantly reduced the production of antiviral immune factors and dampened STING-induced innate immune responses. Mechanistically, we discovered that STING interacts with transketolase (TKT), a key enzyme in the non-oxidative branch of the PPP, and reduces its ubiquitination via the E3 ubiquitin ligase UBE3A, stabilizing TKT. Silencing TKT or inhibiting its activity with oxythiamine diminished antiviral immune factor production.

CONCLUSION

Our findings reveal that the PPP plays a synergistic role in generating antiviral immune factors during viral infection and suggest that PPP activation could serve as an adjunct strategy for antiviral therapy.

Chromosomal instability is associated with prognosis and efficacy of bevacizumab after resection of colorectal cancer liver metastasis

INTRODUCTION

Individualized treatment of colorectal cancer liver metastases (CRLM) remains challenging due to differences in the severity of metastatic disease and tumour biology. Exploring specific prognostic risk subgroups is urgently needed. The current study aimed to investigate the prognostic value of chromosomal instability (CIN) in patients with initially resectable CRLM and the predictive value of CIN for the efficacy of bevacizumab.

METHODS

Ninety-one consecutive patients with initially resectable CRLM who underwent curative liver resection from 2006 to 2018 at Sun Yat-sen University Cancer Center were selected for analysis. CIN was evaluated by automated digital imaging systems. Immunohistochemistry (IHC) was performed to detect interleukin-6 (IL-6), vascular endothelial growth factor A (VEGFA) and CD31 expression in paraffin-embedded specimens. Recurrence-free survival (RFS) and overall survival (OS) were analysed using the Kaplan-Meier method and Cox regression models.

RESULTS

Patients with high chromosomal instability (CIN-H) had a worse 3-year RFS rate (HR, 1.953; 95% CI, 1.001-3.810; p = 0.049) and a worse 3-year OS rate (HR, 2.449; 95% CI, 1.150-5.213; p = 0.016) than those with low chromosomal instability (CIN-L). CIN-H was identified as an independent prognostic factor for RFS (HR, 2.569; 95% CI, 1.078-6.121; p = 0.033) and OS (HR, 3.852; 95% CI, 1.173-12.645; p = 0.026) in the multivariate analysis. The protein levels of IL-6, VEGFA and CD31 were upregulated in patients in the CIN-H group compared to those in the CIN-L group in both primary tumour and liver metastases tissues. Among them, 22 patients with recurrent tumours were treated with first-line bevacizumab treatment and based on the clinical response assessment, disease control rates were adversely associated with chromosomal instability (p = 0.043).

CONCLUSIONS

Our study showed that high chromosomal instability is a negative prognostic factor for patients with initially resectable CRLM after liver resection. CIN may have positive correlations with angiogenesis through expression of IL-6-VEGFA axis and be used as a potential predictor of efficacy of bevacizumab.

Pancreatic ductal adenocarcinoma cells reshape the immune microenvironment: Molecular mechanisms and therapeutic targets

Pancreatic ductal adenocarcinoma (PDAC) is a digestive system malignancy characterized by challenging early detection, limited treatment alternatives, and generally poor prognosis. Although there have been significant advancements in immunotherapy for hematological malignancies and various solid tumors in recent decades, with impressive outcomes in recent preclinical and clinical trials, the effectiveness of these therapies in treating PDAC continues to be modest. The unique immunological microenvironment of PDAC, especially the abnormal distribution, complex composition, and variable activation states of tumor-infiltrating immune cells, greatly restricts the effectiveness of immunotherapy. Undoubtedly, integrating data from both preclinical models and human studies helps accelerate the identification of reliable molecules and pathways responsive to targeted biological therapies and immunotherapies, thereby continuously optimizing therapeutic combinations. In this review, we delve deeply into how PDAC cells regulate the immune microenvironment through complex signaling networks, affecting the quantity and functional status of immune cells to promote immune escape and tumor progression. Furthermore, we explore the multi-modal immunotherapeutic strategies currently under development, emphasizing the transformation of the immunosuppressive environment into an anti-tumor milieu by targeting specific molecular and cellular pathways, providing insights for the development of novel treatment strategies.

Recent advances in nanoadjuvant-triggered STING activation for enhanced cancer immunotherapy

The development of effective cancer treatments is a popular in contemporary medical research. Immunotherapy, the fourth most common cancer treatment method, relies on activating autoimmune function to eradicate tumors and exhibits advantages such as a good curative effect and few side effects. In recent years, tumor vaccines that activate the stimulator of interferon genes (STING) pathway are being actively researched in the field of immunotherapy; however, their application is still limited because of the rapid clearance rate of tumor-related lymph nodes and low efficiency of antigen presentation. The rise of nanomedicine has provided new opportunities for solving these problems. By preparing materials with adjuvant effects nanoparticles, the small size of nanoparticles can be exploited to enable the entry of vaccines into tumor-related lymph nodes to accurately deliver STING agonists and activate the immune response. Based on this, this paper reviews various types of nano-adjuvants based on metals, platinum chemotherapy drugs, camptothecin derivatives, deoxyribonucleic acid, etc. and highlights the transformation prospects of these nano-adjuvants in tumor vaccines to provide a reference for promoting the development of nano-medicine and tumor vaccinology.

Robust and Sustained STING Pathway Activation via Hydrogel-Based In Situ Vaccination for Cancer Immunotherapy

The stimulator of interferon genes (STING) pathway is crucial for tumor immunity, leading to the exploration of STING agonists as potential immunotherapy adjuvants. However, their clinical application faces obstacles including poor pharmacokinetics, transient activation, and an immunosuppressive tumor microenvironment (TME). Addressing these limitations, our study aims to develop an injectable silk fibroin hydrogel-based in situ vaccine. It incorporates a nanoscale STING agonist, an immunogenic cell death (ICD) inducer, and an immunomodulator to ensure their controlled and sustained release. cGAMP nanoparticles (cGAMPnps) with a core-shell structure ensure optimal delivery of cGAMP to dendritic cells (DCs), thereby activating the STING pathway and fostering DC maturation. ICD-associated damage-associated molecular patterns amplify and prolong STING activation via enhanced type I IFN and other inflammatory pathways, along with delayed degradation of cGAMP and STING. Furthermore, the STING-driven vascular normalization by cGAMPnps and ICD, in conjunction with immunomodulators like antiprogrammed cell death protein 1 antibody (anti-PD-1 Ab) or OX40 ligand (OX40L), effectively remodels the immunosuppressive TME. This in situ gel vaccine, when used independently or with surgery as neoadjuvant/adjuvant immunotherapy, enhances DC and CD8+ T-cell activation, suppressing tumor progression and recurrence across various immunologically cold tumor models. It revolutionizes the application of STING agonists in cancer immunotherapy, offering substantial promise for improving outcomes across a broad spectrum of malignancies.

Microplastics: an often-overlooked issue in the transition from chronic inflammation to cancer

The presence of microplastics within the human body has raised significant concerns about their potential health implications. Numerous studies have supported the hypothesis that the accumulation of microplastics can trigger inflammatory responses, disrupt the microbiome, and provoke immune reactions due to their physicochemical properties. Chronic inflammation, characterized by tissue damage, angiogenesis, and fibrosis, plays a crucial role in cancer development. It influences cancer progression by altering the tumor microenvironment and impairing immune surveillance, thus promoting tumorigenesis and metastasis. This review explores the fundamental properties and bioaccumulation of microplastics, as well as their potential role in the transition from chronic inflammation to carcinogenesis. Additionally, it provides a comprehensive overview of the associated alterations in signaling pathways, microbiota disturbances, and immune responses. Despite this, the current understanding of the toxicity and biological impacts of microplastics remains limited. To mitigate their harmful effects on human health, there is an urgent need to improve the detection and removal methods for microplastics, necessitating further research and elucidation.

Long-term transcranial ultrasound stimulation regulates neuroinflammation to ameliorate post-myocardial infarction cardiac arrhythmia and remodeling

BACKGROUND

Sympathetic overactivation and neuroinflammation in the paraventricular nucleus (PVN) are crucial factors in post-myocardial infarction (MI) cardiac remodeling and ventricular arrhythmias (VAs). Prior study has indicated that low-intensity focused ultrasound stimulation could attenuate sympathetic neuroinflammation within the PVN to prevent the occurrence of VAs in an acute MI model. Meanwhile, the cGAS-STING pathway has shown potential to ameliorate the neuroinflammatory response. However, the effect and mechanisms of long-term transcranial ultrasound stimulation (LTUS) for modulating neuroinflammation in the chronic stage of MI remain unclear.

OBJECTIVE

This study aimed to ascertain whether LTUS could mitigate post-MI neuroinflammation and improve cardiac arrhythmia and remodeling through the cGAS-STING pathway.

METHODS

Thirty-six SD rats were equally randomized to the sham group (pseudo-MI modeling), chronic MI group (MI modeling), and LTUS group (MI modeling and long-term ultrasound stimulation). Transcranial ultrasound stimulation (15 min/d) was conducted on the PVN for 4 consecutive weeks. After 4-week intervention, echocardiography, electrophysiologic experiments, and histopathologic staining were performed to assess the role of LTUS on post-MI neuroinflammation and cardiac remodeling.

RESULTS

The results indicated that LTUS significantly facilitated microglial M1 to M2 polarization through the cGAS-STING signaling pathway within the PVN. Furthermore, LTUS inhibited MI-induced sympathetic neuroinflammation, thereby improving cardiac dysfunction, ameliorating cardiac remodeling, and reducing VA inducibility.

CONCLUSION

Long-term ultrasound stimulation of the PVN was found to alleviate post-MI neuroinflammation and to improve cardiac remodeling, which might inspire novel insights and clinical strategies for noninvasive neuromodulation and the treatment of post-MI VAs.

Bidirectional regulation of the cGAS-STING pathway in the immunosuppressive tumor microenvironment and its association with immunotherapy

Adaptive anti-tumor immunity is currently dependent on the natural immune system of the body. The emergence of tumor immunotherapy has improved prognosis and prolonged the survival cycle of patients. Current mainstream immunotherapies, including immune checkpoint blockade, chimeric antigen receptor T-cell immunotherapy, and monoclonal antibody therapy, are linked to natural immunity. The cGAS-STING pathway is an important natural immunity signaling pathway that plays an important role in fighting against the invasion of foreign pathogens and maintaining the homeostasis of the organism. Increasing evidence suggests that the cGAS-STING pathway plays a key role in tumor immunity, and the combination of STING-related agonists can significantly enhance the efficacy of immunotherapy and reduce the emergence of immunotherapeutic resistance. However, the cGAS-STING pathway is a double-edged sword, and its activation can enhance anti-tumor immunity and immunosuppression. Immunosuppressive cells, including M2 macrophages, MDSC, and regulatory T cells, in the tumor microenvironment play a crucial role in tumor escape, thereby affecting the immunotherapy effect. The cGAS-STING signaling pathway can bi-directionally regulate this group of immunosuppressive cells, and targeting this pathway can affect the function of immunosuppressive cells, providing new ideas for immunotherapy. In this study, we summarize the activation pathway of the cGAS-STING pathway and its immunological function and elaborate on the key role of this pathway in immune escape mediated by the tumor immunosuppressive microenvironment. Finally, we summarize the mainstream immunotherapeutic approaches related to this pathway and explore ways to improve them, thereby providing guidelines for further clinical services.

Genomic instability as a driver and suppressor of anti-tumor immunity

Genomic instability is a driver and accelerator of tumorigenesis and influences disease outcomes across cancer types. Although genomic instability has been associated with immune evasion and worsened disease prognosis, emerging evidence shows that genomic instability instigates pro-inflammatory signaling and enhances the immunogenicity of tumor cells, making them more susceptible to immune recognition. While this paradoxical role of genomic instability in cancer is complex and likely context-dependent, understanding it is essential for improving the success rates of cancer immunotherapy. In this review, we provide an overview of the underlying mechanisms that link genomic instability to pro-inflammatory signaling and increased immune surveillance in the context of cancer, as well as discuss how genomically unstable tumors evade the immune system. A better understanding of the molecular crosstalk between genomic instability, inflammatory signaling, and immune surveillance could guide the exploitation of immunotherapeutic vulnerabilities in cancer.

Targeting STING signaling for the optimal cancer immunotherapy

Despite the transformative impact of anti-PD-1/PD-L1 therapies, challenges such as low response rates persist. The stimulator of interferon genes (STING) pathway, a crucial element of innate immunity, emerges as a strategic target to overcome these limitations. Understanding its multifaceted functions in cancer, including antigen presentation and response to DNA damage, provides valuable insights. STING agonists, categorized into cyclic dinucleotides (CDNs) and non-CDNs, exhibit promising safety and efficacy profiles. Innovative delivery systems, including antibody-drug conjugates, nanocarriers, and exosome-based therapies, address challenges associated with systemic administration and enhance targeted tumor delivery. Personalized vaccines, such as DT-Exo-STING, showcase the adaptability of STING agonists for individualized treatment. These advancements not only offer new prospects for combination therapies but also pave the way for overcoming resistance mechanisms. This review focuses on the potential of targeting STING pathway to enhance cancer immunotherapy. The integration of STING agonists into cancer immunotherapy holds promise for more effective, personalized, and successful approaches against malignancies, presenting a beacon of hope for the future of cancer treatment.

ER: a critical hub for STING signaling regulation

The Stimulator of Interferon Genes (STING) has a crucial role in mediating the immune response against cytosolic double-stranded DNA (dsDNA) and its activation is critically involved in various diseases. STING is synthesized, modified, and resides in the endoplasmic reticulum (ER), and its ER exit is intimately connected with its signaling. The ER, primarily known for its roles in protein folding, lipid synthesis, and calcium storage, has been identified as a pivotal platform for the regulation of a wide range of STING functions. In this review, we discuss the emerging factors that regulate STING in the ER and examine the interplay between STING signaling and ER pathways, highlighting the impacts of such regulations on immune responses and their potential implications in STING-related disorders.

The relationship between tumor immunity and the cGAS-STING pathway in breast cancer: An immunohistochemical study

Breast cancer (BC) is classified into four major histological subtypes, namely luminal A, luminal B, HER2, and basal-like, and its treatment is based on these subtypes. The use of immune checkpoint inhibitors against BC depends on the expression of PD-1/PD-L1. Another tumor immune system-the cGAS-STING pathway-is a potential target for cancer immunotherapy. However, the status of the cGAS-STING pathway in BC has not been fully established. Therefore, we investigated the expression status of the cGAS-STING pathway and immune-related proteins in BC. We classified 111 BCs into six groups-29 hormone receptor-positive carcinomas, 12 HER2+ carcinomas (HER2), 8 luminal-HER2 carcinomas, 26 triple-negative breast carcinomas (TNBCs), 21 lobular carcinomas (LC), and 15 carcinomas with apocrine differentiation (CAD)-and investigated the relationship between BC and tumor immunity via the cGAS-STING pathway using histopathological and immunohistochemical methods. Expression of cGAS was high in CADs (100%) and low in TNBCs (35%); STING-positive lymphocytes were high in TNBC (85%, P = 0.0054). Expression of pSTAT3 was significantly high in patients with TNBC (≥10%, 88%). The proportion of PD-L1-positive tumor cells was higher in TNBCs (54%) than in other BCs (30%). SRGN expression was significantly higher in the TNBC group than in the other BC groups (58%). Tumor immune responses may differ among tumor subtypes. The cGAS-STING pathway may be functional in TNBC and CAD but not in LC. Therefore, targeting the cGAS-STING pathway might be useful in BC, particularly TNBC and CAD.