Activating STING1-dependent immune signaling in TP53 mutant and wild-type acute myeloid leukemia

The inflammasome-activating poxvirus peptide IAMP29 promotes antimicrobial and anticancer responses

Poxviruses are implicated in a variety of infectious diseases; however, little is known about the molecular mechanisms that underlie the immune response during poxvirus infection. We investigated the function and mechanisms of the monkeypox virus envelope protein (A30L) and its core peptide (IAMP29) during the activation of innate immune responses. The A30L protein and its core peptide, IAMP29 (a 29-amino-acid inflammasome-activating peptide encompassing His40 to Asp69 of A30L), strongly activated the nucleotide-binding oligomerization domain, leucine rich repeat and pyrin domain-containing 3 (NLRP3) inflammasome by inducing the production of mitochondrial reactive oxygen species in human monocytes. Specifically, IAMP29 triggered metabolic reprogramming toward glycolysis and interacted with pyruvate kinase M isoforms (PKM1 and PKM2), thus activating the NLRP3 inflammasome and interleukin (IL)-1β production in human monocytes and murine macrophages. In human primary monocyte-derived macrophages, IAMP29-induced inflammasome activation promoted an antimicrobial response to rapidly growing non-tuberculous mycobacteria. Furthermore, IAMP29 exhibited cytotoxic activity against leukemia cells, which was mediated by pyroptosis and apoptosis. These findings provide insights into the immunological function of the poxvirus envelope peptide and suggest its therapeutic potential.

ZNFX1 is a Novel Master Regulator in Epigenetically-induced Pathogen Mimicry and Inflammasome Signaling in Cancer

DNA methyltransferase and poly(ADP-ribose) polymerase inhibitors (DNMTis, PARPis) induce a stimulator of interferon (IFN) genes (STING)-dependent pathogen mimicry response (PMR) in ovarian (OC) and other cancers. We now show that combining DNMTis and PARPis upregulates expression of a little-studied nucleic-acid sensor, NFX1-type zinc finger-containing 1 protein (ZNFX1). We demonstrate that ZNFX1 is a novel master regulator for PMR induction in mitochondria, serving as a gateway for STING-dependent PMR. In patient OC databases, high ZNFX1 expression levels correlate with advanced stage disease. ZNFX1 expression alone significantly correlates with an increase in overall survival in a phase 3 trial for therapy-resistant OC patients receiving bevacizumab in combination with chemotherapy. In correlative RNA-seq data, inflammasome signaling through ZNFX1 correlates with abnormal vasculogenesis. ZNFX1 controls PMR signaling through the mitochondria and may serve as a biomarker to facilitate offering personalized therapy in OC patients, highlighting the strong translational significance of our findings.

Significance statement

DNA methyltransferase and poly(ADP-ribose) polymerase inhibitors upregulate expression of a novel nucleic-acid sensor, ZNFX1 that serves as a mitochondrial gateway to STING-dependent interferon/inflammasome signaling with tumor suppressor properties in ovarian cancer.

Molecular Subtypes and the Role of TP53 in Diffuse Large B-Cell Lymphoma and Richter Syndrome

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid malignancy and a heterogeneous entity comprised of several biologically distinct subtypes. Recently, novel genetic classifications of DLBCL have been resolved based on common mutational patterns indicative of distinct pathways of transformation. However, the complicated and costly nature of the novel classifiers has precluded their inclusion into routine practice. In view of this, the status of the TP53 gene, which is mutated or deleted in 20-30% of the cases, has emerged as an important prognostic factor for DLBCL patients, setting itself apart from other predictors. TP53 genetic lesions are particularly enriched in a genetic subtype of DLBCL that shares genomic features with Richter Syndrome, highlighting the possibility of a subset of DLBCL arising from the transformation of an occult chronic lymphocytic leukemia-like malignancy, such as monoclonal B-cell lymphocytosis. Patients with TP53-mutated DLBCL, including those with Richter Syndrome, have a particularly poor prognosis and display inferior responses to standard chemoimmunotherapy regimens. The data presented in this manuscript argue for the need for improved and more practical risk-stratification models for patients with DLBCL and show the potential for the use of TP53 mutational status for prognostication and, in prospect, treatment stratification in DLBCL.

Zebularine potentiates anti-tumor immunity by inducing tumor immunogenicity and improving antigen processing through cGAS-STING pathway

DNA methylation is an important epigenetic mechanism involved in the anti-tumor immune response, and DNA methyltransferase inhibitors (DNMTi) have achieved impressive therapeutic outcomes in patients with certain cancer types. However, it is unclear how inhibition of DNA methylation bridges the innate and adaptive immune responses to inhibit tumor growth. Here, we report that DNMTi zebularine reconstructs tumor immunogenicity, in turn promote dendritic cell maturation, antigen-presenting cell activity, tumor cell phagocytosis by APCs, and efficient T cell priming. Further in vivo and in vitro analyses reveal that zebularine stimulates cGAS-STING-NF-κB/IFNβ signaling to enhance tumor cell immunogenicity and upregulate antigen processing and presentation machinery (AgPPM), which promotes effective CD4+ and CD8+ T cell-mediated killing of tumor cells. These findings support the use of combination regimens that include DNMTi and immunotherapy for cancer treatment.

Role of the STING pathway in myeloid neoplasms: a prospero-registered systematic review of principal hurdles of STING on the road to the clinical practice

Myeloid neoplasms are a group of bone marrow diseases distinguished by disruptions in the molecular pathways that regulate the balance between hematopoietic stem cell (HSC) self-renewal and the generation of specialized cells. Cytokines and chemokines, two important components of the inflammatory process, also influence hematological differentiation. In this scenario, immunological dysregulation plays a pivotal role in the pathogenesis of bone marrow neoplasms. The STING pathway recognizes DNA fragments in the cell cytoplasm and triggers an immune response by type I interferons. The role of STING in cancer has not yet been established; however, both actions, as an oncogene or tumor suppressor, have been documented in other types of cancer. Therefore, we performed a systematic review (registered in PROSPERO database #CRD42023407512) to discuss the role of STING pathway in the advancement of pathogenesis and/or prognosis for different myeloid neoplasms. In brief, scientific evidence supports investigations that primarily use cell lines from myeloid neoplasms, such as leukemia. More high-quality research and clinical trials are needed to understand the role of the STING pathway in the pathology of hematological malignancies. Finally, the STING pathway suggests being a promising therapeutic molecular target, particularly when combined with current drug therapies.

Prognostic implications of cGAS and STING gene expression in acute myeloid leukemia

Acute myeloid leukemia (AML) is one of the most threatening hematological malignances. cGAS-STING pathway plays an important role in tumor immunity and development. However, the prognostic role of cGAS-STING pathway in AML remains unknown. Firstly, The expression of cGAS and STING was analyzed by bioinformatics analysis. Subsequently, Bone marrow samples were collected from 120 AML patients and 15 healthy individuals in an independent cohort. The cGAS and STING expression was significantly elevated in AML patients compared with healthy controls. Patients with high cGAS and STING expression had a higher NRAS/KRAS mutation rate and lower complete remission (CR) rate. High cGAS and STING expression was significantly associated with lower overall survival (OS) and disease-free survival (DFS). Our findings revealed that the expression levels of cGAS and STING in AML are elevated. High expression of cGAS and STING correlated with worse OS and DFS and may be a useful biomarker for inferior prognosis in AML patients.

cGAS-STING, inflammasomes and pyroptosis: an overview of crosstalk mechanism of activation and regulation

BACKGROUND

Intracellular DNA-sensing pathway cGAS-STING, inflammasomes and pyroptosis act as critical natural immune signaling axes for microbial infection, chronic inflammation, cancer progression and organ degeneration, but the mechanism and regulation of the crosstalk network remain unclear. Cellular stress disrupts mitochondrial homeostasis, facilitates the opening of mitochondrial permeability transition pore and the leakage of mitochondrial DNA to cell membrane, triggers inflammatory responses by activating cGAS-STING signaling, and subsequently induces inflammasomes activation and the onset of pyroptosis. Meanwhile, the inflammasome-associated protein caspase-1, Gasdermin D, the CARD domain of ASC and the potassium channel are involved in regulating cGAS-STING pathway. Importantly, this crosstalk network has a cascade amplification effect that exacerbates the immuno-inflammatory response, worsening the pathological process of inflammatory and autoimmune diseases. Given the importance of this crosstalk network of cGAS-STING, inflammasomes and pyroptosis in the regulation of innate immunity, it is emerging as a new avenue to explore the mechanisms of multiple disease pathogenesis. Therefore, efforts to define strategies to selectively modulate cGAS-STING, inflammasomes and pyroptosis in different disease settings have been or are ongoing. In this review, we will describe how this mechanistic understanding is driving possible therapeutics targeting this crosstalk network, focusing on the interacting or regulatory proteins, pathways, and a regulatory mitochondrial hub between cGAS-STING, inflammasomes, and pyroptosis.

SHORT CONCLUSION

This review aims to provide insight into the critical roles and regulatory mechanisms of the crosstalk network of cGAS-STING, inflammasomes and pyroptosis, and to highlight some promising directions for future research and intervention.

Mutant p53 gains oncogenic functions through a chromosomal instability-induced cytosolic DNA response

Inactivating TP53 mutations leads to a loss of function of p53, but can also often result in oncogenic gain-of-function (GOF) of mutant p53 (mutp53) proteins which promotes tumor development and progression. The GOF activities of TP53 mutations are well documented, but the mechanisms involved remain poorly understood. Here, we study the mutp53 interactome and find that by targeting minichromosome maintenance complex components (MCMs), GOF mutp53 predisposes cells to replication stress and chromosomal instability (CIN), leading to a tumor cell-autonomous and cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING)-dependent cytosolic DNA response that activates downstream non-canonical nuclear factor kappa light chain enhancer of activated B cell (NC-NF-κB) signaling. Consequently, GOF mutp53-MCMs-CIN-cytosolic DNA-cGAS-STING-NC-NF-κB signaling promotes tumor cell metastasis and an immunosuppressive tumor microenvironment through antagonizing interferon signaling and regulating genes associated with pro-tumorigenic inflammation. Our findings have important implications for understanding not only the GOF activities of TP53 mutations but also the genome-guardian role of p53 and its inactivation during tumor development and progression.

Genetic subtype-guided immunochemotherapy in diffuse large B cell lymphoma: The randomized GUIDANCE-01 trial

We report the results of GUIDANCE-01 (NCT04025593), a randomized, phase II trial of R-CHOP alone or combined with targeted agents (R-CHOP-X) guided by genetic subtyping of newly diagnosed, intermediate-risk, or high-risk diffuse large B cell lymphoma (DLBCL). A total of 128 patients were randomized 1:1 to receive R-CHOP-X or R-CHOP. The study achieved the primary endpoint, showing significantly higher complete response rate with R-CHOP-X than R-CHOP (88% vs. 66%, p = 0.003), with overall response rate of 92% vs. 73% (p = 0.005). Two-year progression-free survival rates were 88% vs. 63% (p < 0.001), and 2-year overall survival rates were 94% vs. 77% (p = 0.001). Meanwhile, post hoc RNA-sequencing validated our simplified genetic subtyping algorithm and previously established lymphoma microenvironment subtypes. Our findings highlight the efficacy and safety of R-CHOP-X, a mechanism-based tailored therapy, which dually targeted genetic and microenvironmental alterations in patients with newly diagnosed DLBCL.

Human endogenous retroviruses as epigenetic therapeutic targets in TP53-mutated diffuse large B-cell lymphoma

TP53 mutation (TP53mut) occurs in 10-20% of diffuse large B-cell lymphoma (DLBCL) cases and serves as an unfavorable biomarker of DLBCL progression. It confers resistance to immunochemotherapy, high-dose chemotherapy, autologous stem cell transplantation, and anti-CD19 chimeric antigen receptor T-cell therapy. Therapeutic targeting of TP53mut remains a significant challenge in DLBCL treatment. Here we assessed TP53mut in 667 patients with newly diagnosed DLBCL, including 576 patients treated with immunochemotherapy rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) and 91 patients with decitabine plus R-CHOP (DR-CHOP, NCT02951728 and NCT04025593). TP53mut independently predicted an inferior prognosis in R-CHOP-treated DLBCL, although this could be mitigated by DR-CHOP treatment. In TP53mut patients, multiple viral regulation pathways were repressed, resulting in the inhibition of immune modulation, as revealed by gene set enrichment analysis. TP53mut DLBCL exhibited increased methyltransferase SUV39H1 expression and H3K9 trimethylation (H3K9me3), contributing to repression of endogenous retroviruses (ERVs) and immunosuppressive tumor microenvironment. In TP53mut DLBCL cell lines, decitabine down-regulated SUV39H1, inhibited H3K9me3 occupancy on ERVs, and triggered ERV expression, thereby unleashing interferons program and CD4+T/CD8+T cell activation. Molecular silencing of SUV39H1 significantly abrogated decitabine-induced H3K9me3 inhibition and ERV expression. In TP53mut patient-derived xenograft models and TP53mut patients, the anti-tumor effect was improved upon the use of combined treatment of decitabine and doxorubicin via SUV39H1-H3K9me3-ERVs axis. Collectively, our findings highlight an ERV regulatory circuitry in TP53mut DLBCL and the crucial roles ERVs for epigenetically reprogramming tumor microenvironment for treating TP53mut-driven cancers.

Comprehensive Analysis and Drug Modulation of Human Endogenous Retrovirus in Hepatocellular Carcinomas

BACKGROUND

Human endogenous retroviruses (HERVs) play an important role in the development of cancer and many diseases. Here, we comprehensively explored the impact of HERVs on hepatocellular carcinomas (HCCs).

METHODS

We employed Telescope to identify HERVs and quantify their expression in the total RNA sequencing data obtained from 254 HCC samples, comprising 254 tumor tissues and 34 matched normal tissues.

RESULTS

In total, 3357 locus-specific activations of HERVs were differentially expressed, and 180 were correlated with patient survival. Using these 180 HERVs for classification, we found four subgroups with survival correlation. Higher expression levels of the 180 HERVs were correlated with poorer survival, while age, AFP, some mutations, and copy and structural variants differed among subgroups. The differential expression of host genes in high expression of these 180 HERVs primarily involved the activation of pathways related to immunity and infection, lipid and atherosclerosis, MAPK and NF-kB signaling, and cytokine-cytokine receptor interactions. Conversely, there was a suppression of pathways associated with RNA processing, including nucleocytoplasmic transport, surveillance and ribosome biogenesis, and transcriptional misregulation in cancer pathways. Almost all genes involved in HERV activation restriction, KRAB zinc finger proteins, RNA nucleocytoplasmic transport, stemness, HLA and antigen processing and presentation, and immune checkpoints were overexpressed in cancerous tissues, and many over-expressed HERV-related nearby genes were correlated with high HERV activation and poor survival. Twenty-three immune and stromal cells showed higher expression in non-cancerous than cancerous tissues, and seven were correlated with HERV activation. Small-molecule modulation of alternative splicing (AS) altered the expression of survival-related HERVs and their activation-related genes, as well as nearby genes.

CONCLUSION

Comprehensive and integrated approaches for evaluating HERV expression and their correlation with specific pathways have the potential to provide new companion diagnostics and therapeutic strategies for HCC.

Human Endogenous Retroviruses in Diseases

Human endogenous retroviruses (HERVs), which are conserved sequences of ancient retroviruses, are widely distributed in the human genome. Although most HERVs have been rendered inactive by evolution, some have continued to exhibit important cytological functions. HERVs in the human genome perform dual functions: on the one hand, they are involved in important physiological processes such as placental development and immune regulation; on the other hand, their aberrant expression is closely associated with the pathological processes of several diseases, such as cancers, autoimmune diseases, and viral infections. HERVs can also regulate a variety of host cellular functions, including the expression of protein-coding genes and regulatory elements that have evolved from HERVs. Here, we present recent research on the roles of HERVs in viral infections and cancers, including the dysregulation of HERVs in various viral infections, HERV-induced epigenetic modifications of histones (such as methylation and acetylation), and the potential mechanisms of HERV-mediated antiviral immunity. We also describe therapies to improve the efficacy of vaccines and medications either by directly or indirectly targeting HERVs, depending on the HERV.

The stimulator of interferon genes (STING) agonists for treating acute myeloid leukemia (AML): current knowledge and future outlook

Acute myeloid leukemia (AML) is an aggressive hematologic cancer in adults. Some patients exhibit restricted T cell infiltration and do not respond to routine treatments. This may be prevented by enhancing adaptive immunity by stimulating innate immune cells inside the tumor microenvironment (TME). To activate the adaptive immunological reaction against tumors, type I interferons (IFNs) can promote the presentation of tumor-specific cytotoxic T lymphocyte (CTL) cell recruitment. During the activation of innate immunity, cyclic di-nucleotides (CDNs) bind to and stimulate the stimulator of interferon genes (STING), a protein localized inside the endoplasmic reticulum (ER) membrane, resulting in the expression of type I IFNs. The efficacy of STING agonists as effective stimulators of the anti-tumor response in AML is being investigated in numerous clinical studies. Therefore, the purpose of this investigation was to thoroughly review existing knowledge in this field and provide perspective into the clinical potential of STING agonists in AML.