Anti-pyroptotic function of TGF-β is suppressed by a synthetic dsRNA analogue in triple negative breast cancer cells

Types of cell death and their relations to host immunological pathways

Various immune pathways have been identified in the host, including TH1, TH2, TH3, TH9, TH17, TH22, TH1-like, and THαβ immune reactions. While TH2 and TH9 responses primarily target multicellular parasites, host immune pathways directed against viruses, intracellular microorganisms (such as bacteria, protozoa, and fungi), and extracellular microorganisms can employ programmed cell death mechanisms to initiate immune responses or execute effective strategies for pathogen elimination. The types of programmed cell death involved include apoptosis, autophagy, pyroptosis, ferroptosis, necroptosis, and NETosis. Specifically, apoptosis is associated with host anti-virus eradicable THαβ immunity, autophagy with host anti-virus tolerable TH3 immunity, pyroptosis with host anti-intracellular microorganism eradicable TH1 immunity, ferroptosis with host anti-intracellular microorganism tolerable TH1-like immunity, necroptosis with host anti-extracellular microorganism eradicable TH22 immunity, and NETosis with host anti-extracellular microorganism tolerable TH17 immunity.

Neferine inhibits the development of lung cancer cells by downregulating TGF-β to regulate MST1/ROS-induced pyroptosis

Non-small cell lung cancer (NSCLC) accounts for ~85% of all lung cancer cases. Neferine is used as a traditional Chinese medicine with many pharmacological effects, including antitumor properties; however, it has not been reported whether neferine plays an anticancer role by causing pyroptosis in NSCLC cells. We used two typical lung cancer cell lines, A549 and H1299, and 42 lung cancer tissue samples to investigate the regulatory effects of neferine on TGF-β and MST1. We also treated lung cancer cells with different concentrations of neferine to study its effects on lung cancer cell survival, migration, invasion, and epithelial-mesenchymal transition (EMT) as well as on pyroptosis. Lentivirus-mediated gain-of-function studies of TGF-β and MST1 were applied to validate the roles of TGF-β and MST1 in lung cancer. Next, we used murine transplanted tumor models to evaluate the effect of neferine treatment on the metastatic capacity of lung cancer tissues. With increasing neferine concentration, the viability, migration, invasion, and EMT capacity of A549 and H1299 cells decreased, whereas pyroptosis increased. Neferine repressed TGF-β expression to modulate the induction of reactive oxygen species (ROS) by MST1. Overexpression of TGF-β in either in vitro or mouse-transplanted A549 cells restored the inhibitory effect of neferine on tumor development. Overexpression of MST1 clearly enhanced pyroptosis. Neferine contributed to pyroptosis by regulating MST1 expression through downregulation of TGF-β to induce ROS formation. Therefore, our study shows that neferine can serve as an adjuvant therapy for NSCLC patients.

Pyroptosis and inflammasomes in cancer and inflammation

Nonprogrammed cell death (NPCD) and programmed cell death (PCD) are two types of cell death. Cell death is significantly linked to tumor development, medication resistance, cancer recurrence, and metastatic dissemination. Therefore, a comprehensive understanding of cell death is essential for the treatment of cancer. Pyroptosis is a kind of PCD distinct from autophagy and apoptosis in terms of the structure and function of cells. The defining features of pyroptosis include the release of an inflammatory cascade reaction and the expulsion of lysosomes, inflammatory mediators, and other cellular substances from within the cell. Additionally, it displays variations in osmotic pressure both within and outside the cell. Pyroptosis, as evidenced by a growing body of research, is critical for controlling the development of inflammatory diseases and cancer. In this paper, we reviewed the current level of knowledge on the mechanism of pyroptosis and inflammasomes and their connection to cancer and inflammatory diseases. This article presents a theoretical framework for investigating the potential of therapeutic targets in cancer and inflammatory diseases, overcoming medication resistance, establishing nanomedicines associated with pyroptosis, and developing risk prediction models in refractory cancer. Given the link between pyroptosis and the emergence of cancer and inflammatory diseases, pyroptosis-targeted treatments may be a cutting-edge treatment strategy.

RIG-I-like receptors: Molecular mechanism of activation and signaling

During RNA viral infection, RIG-I-like receptors (RLRs) recognize the intracellular pathogenic RNA species derived from viral replication and activate antiviral innate immune response by stimulating type 1 interferon expression. Three RLR members, namely, RIG-I, MDA5, and LGP2 are homologous and belong to a subgroup of superfamily 2 Helicase/ATPase that is preferably activated by double-stranded RNA. RLRs are significantly different in gene architecture, RNA ligand preference, activation, and molecular functions. As switchable macromolecular sensors, RLRs' activities are tightly regulated by RNA ligands, ATP, posttranslational modifications, and cellular cofactors. We provide a comprehensive review of the structure and function of the RLRs and summarize the molecular understanding of sensing and signaling events during the RLR activation process. The key roles RLR signaling play in both anti-infection and immune disease conditions highlight the therapeutic potential in targeting this important molecular pathway.

Targeting pyroptosis in breast cancer: biological functions and therapeutic potentials on It

Pyroptosis is a lytic and inflammatory type of programmed cell death that is mediated by Gasdermin proteins (GSDMs). Attractively, recent evidence indicates that pyroptosis involves in the development of tumors and can serve as a new strategy for cancer treatment. Here, we present a basic knowledge of pyroptosis, and an overview of the expression patterns and roles of GSDMs in breast cancer. In addition, we further summarize the available evidence of pyroptosis in breast cancer progression and give insight into the clinical potential of applying pyroptosis in anticancer strategies for breast cancer. This review will deepen our understanding of the relationship between pyroptosis and breast cancer, and provide a novel potential therapeutic avenue for breast cancer.

Identification and validation of the pyroptosis-related long noncoding rna signature to predict the prognosis of patients with bladder cancer

Bladder cancer ranked the second most frequent tumor among urological malignancies. This work investigated bladder cancer prognosis, including the relevance of pyroptosis-related long noncoding RNA (lncRNA) in it and its potential roles. The Cancer Genome Atlas database offered statistics on lncRNAs and clinical data from 411 bladder cancer patients. Pearson correlation analysis was used to evaluate pyroptosis-related lncRNAs. To explore prognosis-associated lncRNAs, we performed univariate Cox regression, least absolute shrinkage and selection operator regression analyses, as well as the Kaplan-Meier method. Multivariate Cox analysis was leveraged to establish the risk score model. Afterward, a nomogram was constructed according to the risk score and clinical variables. Finally, to investigate the potential functions of pyroptosis-related lncRNAs, gene set enrichment analysis was employed. Eleven pyroptosis-related lncRNAs were screened to be closely associated with patients prognosis. On this foundation, a risk score model was created to classify patients into high and low risk groups. The signature was shown to be an independent prognostic factor (P < .001) with an area under the curve of 0.730. Then a nomogram was established including risk scores and clinical characteristics. The nomogram prediction effect is excellent, with a concordance index of 0.86. The 11-lncRNAs signature was associated with the supervision of oxidative stress, epithelial-mesenchymal transition, cell adhesion, TGF-β, and Wingless and INT-1 signaling pathway, according to the gene set enrichment analysis. Our findings indicate that pyroptosis-related lncRNAs, which may affect tumor pathogenesis in many ways, might be exploited to assess the prognosis of bladder cancer patients.

Roles of TGF-β in cancer hallmarks and emerging onco-therapeutic design

Transforming growth factor-beta (TGF-β) is a double-edged sword in cancer treatment because of its pivotal yet complex and roles played during cancer initiation/development. Current anti-cancer strategies involving TGF-β largely view TGF-β as an onco-therapeutic target that not only substantially hinders its full utilisation for cancer control, but also considerably restricts innovations in this field. Thereby, how to take advantages of therapeutically favourable properties of TGF-β for cancer management represents an interesting and less investigated problem. Here, by categorising cancer hallmarks into four critical transition events and one enabling characteristic controlling cancer initiation and progression, and delineating TGF-β complexities according to these cancer traits, we identify the suppressive role of TGF-β in tumour initiation and early-stage progression and its promotive functionalities in cancer metastasis as well as other cancer hallmarks. We also propose the feasibility and possible scenarios of combining cold atmospheric plasma (CAP) with onco-therapeutics utilising TGF-β for cancer control given the intrinsic properties of CAP against cancer hallmarks.

Immune landscape and risk prediction based on pyroptosis-related molecular subtypes in triple-negative breast cancer

The survival outcome of triple-negative breast cancer (TNBC) remains poor, with difficulties still existing in prognosis assessment and patient stratification. Pyroptosis, a newly discovered form of programmed cell death, is involved in cancer pathogenesis and progression. The role of pyroptosis in the tumor microenvironment (TME) of TNBC has not been fully elucidated. In this study, we disclosed global alterations in 58 pyroptosis-related genes at somatic mutation and transcriptional levels in TNBC samples collected from The Cancer Genome Atlas and Gene Expression Omnibus databases. Based on the expression patterns of genes related to pyroptosis, we identified two molecular subtypes that harbored different TME characteristics and survival outcomes. Then, based on differentially expressed genes between two subtypes, we established a 12-gene score with robust efficacy in predicting short- and long-term overall survival of TNBC. Patients at low risk exhibited a significantly better prognosis, more antitumor immune cell infiltration, and higher expression of immune checkpoints including PD-1, PD-L1, CTLA-4, and LAG3. The comprehensive analysis of the immune landscape in TNBC indicated that alterations in pyroptosis-related genes were closely related to the formation of the immune microenvironment and the intensity of the anticancer response. The 12-gene score provided new information on the risk stratification and immunotherapy strategy for highly heterogeneous patients with TNBC.

The intersection molecule MDA5 in Cancer and COVID-19

The connections between pattern recognition receptors (PRRs) and pathogen-associated molecular patterns (PAMPs) constitutes the crucial signaling pathways in the innate immune system. Cytoplasmic nucleic acid sensor melanoma differentiation-associated gene 5 (MDA5) serves as an important pattern recognition receptor in the innate immune system by recognizing viral RNA. MDA5 also plays a role in identifying the cytoplasmic RNA from damaged, dead cancer cells or autoimmune diseases. MDA5’s recognition of RNA triggers innate immune responses, induces interferon (IFN) response and a series of subsequent signaling pathways to produce immunomodulatory factors and inflammatory cytokines. Here we review the latest progress of MDA5 functions in triggering anti-tumor immunity by sensing cytoplasmic dsRNA, and recognizing SARS-CoV-2 virus infection for antiviral response, in which the virus utilizes multiple ways to evade the host defense mechanism.

The role of pyroptosis and its crosstalk with immune therapy in breast cancer

Pyroptosis is a brand-new category of programmed cell death (PCD) that is brought on by multitudinous inflammasomes, which can recognize several stimuli to pilot the cleavage of and activate inflammatory cytokines like IL-18 and IL-1β is believed to have dual effects on the development of multiple cancers including breast cancer. However, pyroptosis has different effects on cancers depending on the type of tissues and their distinct heredity. Recently, the association between pyroptosis and breast cancer has received more and more attention, and it is thought that inducing pyroptosis could be used as a cancer treatment option. In addition, a great deal of evidence accumulating over the past decades has evinced the crosstalk between pyroptosis and tumor immunological therapy. Thus, a comprehensive summary combining the function of pyroptosis in breast cancer and antitumor immunity is imperative. We portray the prevalent knowledge of the multidimensional roles of pyroptosis in cancer and summarize the pyroptosis in breast cancer principally. Moreover, we elucidate the influence of inflammasomes and pyroptosis-produced cytokines on the tumor microenvironment (TME) of breast cancer. Taken together, we aim to provide a clue to harness pyroptosis rationally and apply it to augment immunotherapy efficiency for breast cancer.

Targeting regulated cell death (RCD) with small-molecule compounds in triple-negative breast cancer: a revisited perspective from molecular mechanisms to targeted therapies

Triple-negative breast cancer (TNBC) is a subtype of human breast cancer with one of the worst prognoses, with no targeted therapeutic strategies currently available. Regulated cell death (RCD), also known as programmed cell death (PCD), has been widely reported to have numerous links to the progression and therapy of many types of human cancer. Of note, RCD can be divided into numerous different subroutines, including autophagy-dependent cell death, apoptosis, mitotic catastrophe, necroptosis, ferroptosis, pyroptosis and anoikis. More recently, targeting the subroutines of RCD with small-molecule compounds has been emerging as a promising therapeutic strategy, which has rapidly progressed in the treatment of TNBC. Therefore, in this review, we focus on summarizing the molecular mechanisms of the above-mentioned seven major RCD subroutines related to TNBC and the latest progress of small-molecule compounds targeting different RCD subroutines. Moreover, we further discuss the combined strategies of one drug (e.g., narciclasine) or more drugs (e.g., torin-1 combined with chloroquine) to achieve the therapeutic potential on TNBC by regulating RCD subroutines. More importantly, we demonstrate several small-molecule compounds (e.g., ONC201 and NCT03733119) by targeting the subroutines of RCD in TNBC clinical trials. Taken together, these findings will provide a clue on illuminating more actionable low-hanging-fruit druggable targets and candidate small-molecule drugs for potential RCD-related TNBC therapies.

PolyI:C attenuates transforming growth factor-β signaling to induce cytostasis of surrounding cells by secreted factors in triple-negative breast cancer

The activation of RIG‐I‐like receptor (RLR) signaling in cancer cells is widely recognized as a critical cancer therapy method. The expected mechanism of RLR ligand‐mediated cancer therapy involves the promotion of cancer cell death and strong induction of interferon (IFN)‐β that affects the tumor microenvironment. We have recently shown that activation of RLR signaling in triple‐negative breast cancer cells (TNBC) attenuates transforming growth factor‐β (TGF‐β) signaling, which partly contributes to the promotion of cancer cell pyroptosis. However, the consequences of suppression of TGF‐β signaling by RLR ligands with respect to IFN‐β‐mediated tumor suppression are not well characterized. This study showed that transfection of a typical RLR ligand polyI:C in cancer cells produces significant levels of IFN‐β, which inhibits the growth of the surrounding cancer cells. In addition, IFN‐β‐induced cell cycle arrest in surrounding cancer cells was inhibited by the expression of constitutively active Smad3. Constitutively active Smad3 suppresses IFN‐β expression through the alleviation of IFN regulatory factor 3 binding to the canonical target genes, as suggested by ChIP sequencing analysis. Based on these findings, a new facet of the protumorigenic function of TGF‐β that suppresses IFN‐β expression is suggested when RLR‐mediated cancer treatment is used in TNBC.

A Novel Pyroptosis-Associated Long Non-coding RNA Signature Predicts Prognosis and Tumor Immune Microenvironment of Patients With Breast Cancer

Background: Pyroptosis, a kind of programmed cell death characterized by the rupture of cell membranes and the release of inflammatory substances, plays an important role in the occurrence and development of cancer. However, few studies focus on the pyroptosis-associated long non-coding RNAs (lncRNAs) in breast cancer (BC). The prognostic value of pyroptosis-associated lncRNAs and their relationship with tumor microenvironment (TME) in BC remain unclear. The purpose of this study was to explore the prognostic role of pyroptosis-associated lncRNAs and their relationship with TME in BC.

Methods: The transcriptome data and clinical data of female BC patients were downloaded from The Cancer Genome Atlas (TCGA) database. A total of 937 patients were randomly assigned to either training set or validation set. A pyroptosis-associated lncRNA signature was constructed in the training set and verified in the validation set. Functional analysis and immune microenvironment analysis related to pyroptosis-associated lncRNAs were performed. A nomogram based on the risk score and clinical characteristics was established.

Results: A 9-pyroptosis-associated lncRNA signature was constructed to separate BC patients into two risk groups. High-risk patients had poorer prognosis than low-risk patients. The risk score was proven to be an independent prognostic factor by multivariate Cox regression analysis. Function analysis and immune microenvironment analysis showed that low-risk BC tended to be an immunologically “hot” tumor. A nomogram was constructed with risk score and clinical characteristics. Receiver operating characteristic curve (ROC) analysis demonstrated credible predictive power of the nomogram. The area under time-dependent ROC curve (AUC) reached 0.880 at 1 year, 0.804 at 3 years, and 0.769 at 5 years in the training set, and 0.799 at 1 year, 0.794 at 3 years, and 0.728 at 5 years in the validation set.

Conclusion: We identified a novel pyroptosis-associated lncRNA signature that was an independent prognostic indicator for BC patients. Pyroptosis-associated lncRNAs had potential relationship with the immune microenvironment and might be therapeutic targets for BC patients.