3'-epi-12β-hydroxyfroside-mediated autophagy degradation of RIPK1/RIPK3 necrosomes leads to anergy of immunogenic cell death in triple-negative breast cancer cells

Toxicarioside H-mediated modulation of the immune microenvironment attenuates ovalbumin-induced allergic airway inflammation by inhibiting NETosis

PURPOSE

Our team identified a new cardiac glycoside, Toxicarioside H (ToxH), in a tropical plant. Previous research has indicated the potential of cardenolides in mitigating inflammation, particularly in the context of NETosis. Therefore, this study sought to examine the potential of ToxH in attenuating allergic airway inflammation by influencing the immune microenvironment.

METHODS

An OVA-induced airway inflammation model was established in BALB/c mice. After the experiment was completed, serum, bronchoalveolar lavage fluid (BALF), and lung tissue samples were collected and further examined using H&E and PAS staining, flow cytometry, immunofluorescence observation, and Western blot analysis.

RESULTS

Treatment with ToxH was found to be effective in reducing airway inflammation and mucus production. This was accompanied by an increase in Th1 cytokines (IFN-γ, IL-2, and TNF-β), and the Th17 cytokine IL-17, while levels of Th2 cytokines (IL-4, IL-5, and IL-13) and Treg cytokines (IL-10 and TGF-β1) were decreased in both the bronchoalveolar lavage fluid (BALF) and the CD45+ immune cells in the lungs. Additionally, ToxH inhibited the infiltration of inflammatory cells and decreased the number of pulmonary CD44+ memory T cells, while augmenting the numbers of Th17 and Treg cells. Furthermore, the neutrophil elastase inhibitor GW311616A was observed to suppress airway inflammation and mucus production, as well as alter the secretion of immune Th1, Th2, Th17, and Treg cytokines in the lung CD45+ immune cells. Moreover, our study also demonstrated that treatment with ToxH efficiently inhibited ROS generation, thereby rectifying the dysregulation of immune cells in the immune microenvironment in OVA-induced allergic asthma.

CONCLUSIONS

Our findings indicate that ToxH could serve as a promising therapeutic intervention for allergic airway inflammation and various other inflammatory disorders. Modulating the balance of Th1/Th2 and Treg/Th17 cells within the pulmonary immune microenvironment may offer an effective strategy for controlling allergic airway inflammation.

Progesterone modulates the immune microenvironment to suppress ovalbumin-induced airway inflammation by inhibiting NETosis

Studies have demonstrated that prior to puberty, girls have a lower incidence and severity of asthma symptoms compared to boys. This study aimed to explore the role of progesterone (P4), a sex hormone, in reducing inflammation and altering the immune microenvironment in a mouse model of allergic asthma induced by OVA. Female BALB/c mice with or without ovariectomy to remove the influence of sex hormones were used for the investigations. Serum, bronchoalveolar lavage fluid (BALF), and lung tissue samples were collected for analysis. The results indicated that P4 treatment was effective in decreasing inflammation and mucus secretion in the lungs of OVA-induced allergic asthma mice. P4 treatment also reduced the influx of inflammatory cells into the BALF and increased the levels of Th1 and Th17 cytokines while decreasing the levels of Th2 and Treg cytokines in both BALF and lung microenvironment CD45+ T cells. Furthermore, P4 inhibited the infiltration of inflammatory cells into the lungs, suppressed NETosis, and reduced the number of pulmonary CD4+ T cells while increasing the number of regulatory T cells. The neutrophil elastase inhibitor GW311616A also suppressed airway inflammation and mucus production and modified the secretion of immune Th1, Th2, Th17, and Treg cytokines in lung CD45+ immune cells. These changes led to an alteration of the immunological milieu with increased Th1 and Th17 cells, accompanied by decreased Th2, Treg, and CD44+ T cells, similar to the effects of P4 treatment. Treatment with P4 inhibited NETosis by suppressing the p38 pathway activation, leading to reduced reactive oxygen species production. Moreover, P4 treatment hindered the release of double-stranded DNA during NETosis, thereby influencing the immune microenvironment in the lungs. These findings suggest that P4 treatment may be beneficial in reducing inflammation associated with allergic asthma by modulating the immune microenvironment. In conclusion, this research indicates the potential of P4 as a therapeutic agent for ameliorating inflammation in OVA-induced allergic asthma mice.

Rosuvastatin attenuates airway inflammation and remodeling in a chronic allergic asthma model through modulation of the AMPKα signaling pathway

The efficacy of rosuvastatin in reducing allergic inflammation has been established. However, its potential to reduce airway remodeling has yet to be explored. This study aimed to evaluate the efficacy of rosuvastatin in reducing airway inflammation and remodeling in a mouse model of chronic allergic asthma induced by sensitization and challenge with OVA. Histology of the lung tissue and the number of inflammatory cells in bronchoalveolar lavage fluid (BALF) showed a marked decrease in airway inflammation and remodeling in mice treated with rosuvastatin, as evidenced by a decrease in goblet cell hyperplasia, collagen deposition, and smooth muscle hypertrophy. Furthermore, levels of inflammatory cytokines, angiogenesis-related factors, and OVA-specific IgE in BALF, plasma, and serum were all reduced upon treatment with rosuvastatin. Western blotting was employed to detect AMPK expression, while immunohistochemistry staining was used to observe the expression of remodeling signaling proteins such as α-SMA, TGF-β, MMP-9, and p-AMPKα in the lungs. It was found that the activity of 5'-adenosine monophosphate-activated protein kinase alpha (AMPKα) was significantly lower in the lungs of OVA-induced asthmatic mice compared to Control mice. However, the administration of rosuvastatin increased the ratio of phosphorylated AMPK to total AMPKα, thus inhibiting the formation of new blood vessels, as indicated by CD31-positive staining mainly in the sub-epithelial region. These results indicate that rosuvastatin can effectively reduce airway inflammation and remodeling in mice with chronic allergic asthma caused by OVA, likely due to the reactivation of AMPKα and a decrease in angiogenesis.

GSK3β and UCHL3 govern RIPK4 homeostasis via deubiquitination to enhance tumor metastasis in ovarian cancer

Receptor-interacting protein kinase 4 (RIPK4) is increasingly recognized as a pivotal player in ovarian cancer, promoting tumorigenesis and disease progression. Despite its significance, the posttranslational modifications dictating RIPK4 stability in ovarian cancer remain largely uncharted. In this study, we first established that RIPK4 levels are markedly higher in metastatic than in primary ovarian cancer tissues through single-cell sequencing. Subsequently, we identified UCHL3 as a key deubiquitinase that regulates RIPK4. We elucidate the mechanism that UCHL3 interacts with and deubiquitinates RIPK4 at the K469 site, removing the K48-linked ubiquitin chain and thus enhancing RIPK4 stabilization. Intriguingly, inhibition of UCHL3 activity using TCID leads to increased RIPK4 ubiquitination and degradation. Furthermore, we discovered that GSK3β-mediated phosphorylation of RIPK4 at Ser420 enhances its interaction with UCHL3, facilitating further deubiquitination and stabilization. Functionally, RIPK4 was found to drive the proliferation and metastasis of ovarian cancer in a UCHL3-dependent manner both in vitro and in vivo. Importantly, positive correlations between RIPK4 and UCHL3 protein expression levels were observed, with both serving as indicators of poor prognosis in ovarian cancer patients. Overall, this study uncovers a novel pathway wherein GSK3β-induced phosphorylation of RIPK4 strengthens its interaction with UCHL3, leading to increased deubiquitination and stabilization of RIPK4, thereby promoting ovarian cancer metastasis. These findings offer new insights into the molecular underpinnings of ovarian cancer and highlight potential therapeutic targets for enhancing antitumor efficacy.

Investigating autophagy and intricate cellular mechanisms in hepatocellular carcinoma: Emphasis on cell death mechanism crosstalk

Hepatocellular carcinoma (HCC) stands as a formidable global health challenge due to its prevalence, marked by high mortality and morbidity rates. This cancer type exhibits a multifaceted etiology, prominently linked to viral infections, non-alcoholic fatty liver disease, and genomic mutations. The inherent heterogeneity of HCC, coupled with its proclivity for developing drug resistance, presents formidable obstacles to effective therapeutic interventions. Autophagy, a fundamental catabolic process, plays a pivotal role in maintaining cellular homeostasis, responding to stressors such as nutrient deprivation. In the context of HCC, tumor cells exploit autophagy, either augmenting or impeding its activity, thereby influencing tumorigenesis. This comprehensive review underscores the dualistic role of autophagy in HCC, acting as both a pro-survival and pro-death mechanism, impacting the trajectory of tumorigenesis. The anti-carcinogenic potential of autophagy is evident in its ability to enhance apoptosis and ferroptosis in HCC cells. Pertinently, dysregulated autophagy fosters drug resistance in the carcinogenic context. Both genomic and epigenetic factors can regulate autophagy in HCC progression. Recognizing the paramount importance of autophagy in HCC progression, this review introduces pharmacological compounds capable of modulating autophagy-either inducing or inhibiting it, as promising avenues in HCC therapy.

Autophagy flux in bladder cancer: Cell death crosstalk, drug and nanotherapeutics

Autophagy, a self-digestion mechanism, has emerged as a promising target in the realm of cancer therapy, particularly in bladder cancer (BCa), a urological malignancy characterized by dysregulated biological processes contributing to its progression. This highly conserved catabolic mechanism exhibits aberrant activation in pathological events, prominently featured in human cancers. The nuanced role of autophagy in cancer has been unveiled as a double-edged sword, capable of functioning as both a pro-survival and pro-death mechanism in a context-dependent manner. In BCa, dysregulation of autophagy intertwines with cell death mechanisms, wherein pro-survival autophagy impedes apoptosis and ferroptosis, while pro-death autophagy diminishes tumor cell survival. The impact of autophagy on BCa progression is multifaceted, influencing metastasis rates and engaging with the epithelial-mesenchymal transition (EMT) mechanism. Pharmacological modulation of autophagy emerges as a viable strategy to impede BCa progression and augment cell death. Notably, the introduction of nanoparticles for targeted autophagy regulation holds promise as an innovative approach in BCa suppression. This review underscores the intricate interplay of autophagy with cell death pathways and its therapeutic implications in the nuanced landscape of bladder cancer.

Autocrine phosphatase PDP2 inhibits ferroptosis by dephosphorylating ACSL4 in the Luminal A Breast Cancer

Phosphatases can dephosphorylate phosphorylated kinases, leading to their inactivation, and ferroptosis is a type of cell death. Therefore, our aim is to identify phosphatases associated with ferroptosis by analyzing the differentially expressed genes (DEGs) of the Luminal A Breast Cancer (LumABC) cohort from the Cancer Genome Atlas (TCGA). An analysis of 260 phosphatase genes from the GeneCard database revealed that out of the 28 DEGs with high expression, only the expression of pyruvate dehydrogenase phosphatase 2 (PDP2) had a significant correlation with patient survival. In addition, an analysis of DEGs using gene ontology, Kyoto Encyclopedia of Genes and Genomes and gene set enrichment analysis revealed a significant variation in the expression of ferroptosis-related genes. To further investigate this, we analyzed 34 ferroptosis-related genes from the TCGA-LumABC cohort. The expression of long-chain acyl-CoA synthetase 4 (ACSL4) was found to have the highest correlation with the expression of PDP2, and its expression was also inversely proportional to the survival rate of patients. Western blot experiments using the MCF-7 cell line showed that the phosphorylation level of ACSL4 was significantly lower in cells transfected with the HA-PDP2 plasmid, and ferroptosis was correspondingly reduced (p < 0.001), as indicated by data from flow cytometry detection of membrane-permeability cell death stained with 7-aminoactinomycin, lipid peroxidation, and Fe2+. Immunoprecipitation experiments further revealed that the phosphorylation level of ACSL4 was only significantly reduced in cells where PDP2 and ACSL4 co-precipitated. These findings suggest that PDP2 may act as a phosphatase to dephosphorylate and inhibit the activity of ACSL4, which had been phosphorylated and activated in LumABC cells. Further experiments are needed to confirm the molecular mechanism of PDP2 inhibiting ferroptosis.

Discovery of Novel Isoquinoline Analogues as Dual Tubulin Polymerization/V-ATPase Inhibitors with Immunogenic Cell Death Induction

Cancer immunotherapy has revolutionized clinical advances in a variety of cancers. Due to the low immunogenicity of the tumor, only a few patients can benefit from it. Specific microtubule inhibitors can effectively induce immunogenic cell death and improve immunogenicity of the tumor. A series of isoquinoline derivatives based on the natural products podophyllotoxin and diphyllin were designed and synthesized. Among them, F10 showed robust antiproliferation activity against four human cancer cell lines, and it was verified that F10 exerted antiproliferative activity by inhibiting tubulin and V-ATPase. Further studies indicated that F10 is able to induce immunogenic cell death in addition to apoptosis. Meanwhile, F10 inhibited tumor growth in an RM-1 homograft model with enhanced T lymphocyte infiltration. These results suggest that F10 may be a promising lead compound for the development of a new generation of microtubule drugs.

RIPK1 inhibitors: A key to unlocking the potential of necroptosis in drug development

Within the field of medical science, there is a great deal of interest in investigating cell death pathways in the hopes of discovering new drugs. Over the past two decades, pharmacological research has focused on necroptosis, a cell death process that has just been discovered. Receptor-interacting protein kinase 1 (RIPK1), an essential regulator in the cell death receptor signalling pathway, has been shown to be involved in the regulation of important events, including necrosis, inflammation, and apoptosis. Therefore, researching necroptosis inhibitors offers novel ways to treat a variety of disorders that are not well-treated by the therapeutic medications now on the market. The research and medicinal potential of RIPK1 inhibitors, a promising class of drugs, are thoroughly examined in this study. The journey from the discovery of Necrostatin-1 (Nec-1) to the recent advancements in RIPK1 inhibitors is marked by significant progress, highlighting the integration of traditional medicinal chemistry approaches with modern technologies like high-throughput screening and DNA-encoded library technology. This review presents a thorough exploration of the development and therapeutic potential of RIPK1 inhibitors, a promising class of compounds. Simultaneously, this review highlights the complex roles of RIPK1 in various pathological conditions and discusses potential inhibitors discovered through diverse pathways, emphasizing their efficacy against multiple disease models, providing significant guidance for the expansion of knowledge about RIPK1 and its inhibitors to develop more selective, potent, and safe therapeutic agents.

Amplifying "eat me signal" by immunogenic cell death for potentiating cancer immunotherapy

Immunogenic cell death (ICD) is a unique mode of cell death, which can release immunogenic damage-associated molecular patterns (DAMPs) and tumor-associated antigens to trigger long-term protective antitumor immune responses. Thus, amplifying "eat me signal" during tumor ICD cascade is critical for cancer immunotherapy. Some therapies (radiotherapy, photodynamic therapy (PDT), photothermal therapy (PTT), etc.) and inducers (chemotherapeutic agents, etc.) have enabled to initiate and/or facilitate ICD and activate antitumor immune responses. Recently, nanostructure-based drug delivery systems have been synthesized for inducing ICD through combining treatment of chemotherapeutic agents, photosensitizers for PDT, photothermal transformation agents for PTT, radiosensitizers for radiotherapy, etc., which can release loaded agents at an appropriate dosage in the designated place at the appropriate time, contributing to higher efficiency and lower toxicity. Also, immunotherapeutic agents in combination with nanostructure-based drug delivery systems can produce synergetic antitumor effects, thus potentiating immunotherapy. Overall, our review outlines the emerging ICD inducers, and nanostructure drug delivery systems loading diverse agents to evoke ICD through chemoradiotherapy, PDT, and PTT or combining immunotherapeutic agents. Moreover, we discuss the prospects and challenges of harnessing ICD induction-based immunotherapy, and highlight the significance of multidisciplinary and interprofessional collaboration to promote the optimal translation of this treatment strategy.

Gankyrin inhibits ferroptosis through the p53/SLC7A11/GPX4 axis in triple-negative breast cancer cells

Gankyrin is found in high levels in triple-negative breast cancer (TNBC) and has been established to form a complex with the E3 ubiquitin ligase MDM2 and p53, resulting in the degradation of p53 in hepatocarcinoma cells. Therefore, this study sought to determine whether gankyrin could inhibit ferroptosis through this mechanism in TNBC cells. The expression of gankyrin was investigated in relation to the prognosis of TNBC using bioinformatics. Co-immunoprecipitation and GST pull-down assays were then conducted to determine the presence of a gankyrin and MDM2 complex. RT-qPCR and immunoblotting were used to examine molecules related to ferroptosis, such as gankyrin, p53, MDM2, SLC7A11, and GPX4. Additionally, cell death was evaluated using flow cytometry detection of 7-AAD and a lactate dehydrogenase release assay, as well as lipid peroxide C11-BODIPY. Results showed that the expression of gankyrin is significantly higher in TNBC tissues and cell lines, and is associated with a poor prognosis for patients. Subsequent studies revealed that inhibiting gankyrin activity triggered ferroptosis in TNBC cells. Additionally, silencing gankyrin caused an increase in the expression of the p53 protein, without altering its mRNA expression. Co-immunoprecipitation and GST pull-down experiments indicated that gankyrin and MDM2 form a complex. In mouse embryonic fibroblasts lacking both MDM2 and p53, this gankyrin/MDM2 complex was observed to ubiquitinate p53, thus raising the expression of molecules inhibited by ferroptosis, such as SLC7A11 and GPX4. Furthermore, silencing gankyrin in TNBC cells disrupted the formation of the gankyrin/MDM2 complex, hindered the degradation of p53, increased SLC7A11 expression, impeded cysteine uptake, and decreased GPX4 production. Our findings suggest that TNBC cells are able to prevent cell ferroptosis through the gankyrin/p53/SLC7A11/GPX4 signaling pathway, indicating that gankyrin may be a useful biomarker for predicting TNBC prognosis or a potential therapeutic target.

Afzelin induces immunogenic cell death against lung cancer by targeting NQO2

BACKGROUND

Lung cancer is one of the most common malignant cancers worldwide. Previous studies have shown that Afzelin, a flavonoid, possesses anticancer activity. The aim of this study was to explore Afzelin's effect on lung cancer cells and delineate potential anti-cancer mechanism.

METHODS

The effect of Afzelin on cell viability, proliferation, and apoptosis of lung cancer cells i.e., A549 and H1299 cells, was studied. The targets for Afzelin in lung cancer were predicted using SwissTargetPrediction, Next, the GO analysis and pathway enrichment were analyzed using String. For in vitro studies, the overexpression plasmid of NQO2, the identified target of Afzelin, was transfected into Afzelin-treated cells to verify the regulatory role of Afzelin on its target and signaling pathway.

RESULTS

In in vitro studies, Afzelin markedly inhibited cell viability, proliferation, and raised apoptotic rate of A549 and H1299 cells. In addition, Afzelin activated endoplasmic reticulum (ER) stress and increased ATP, HMGB1, and CRT levels in lung cancer cells, indicating that Afzelin induced immunogenic cell death (ICD). SwissTargetPrediction identified NQO2 as a target of Afzelin. Further, Afzelin markedly inhibited NQO2 protein expression and in turn, overexpression of NQO2 attenuated the effect of Afzelin on A549 and H1299 cells.

CONCLUSION

Afzelin inhibits lung cancer progression by targeting NQO2, in turn, activating ER stress and inducing ICD.