RIPK3 signaling and its role in the pathogenesis of cancers

Modulation of NLRP3 inflammasome-related-inflammation via RIPK1/RIPK3-DRP1 or HIF-1α signaling by phenothiazine in hypothermic and normothermic neuroprotection after acute ischemic stroke

BACKGROUND

Inflammation and subsequent mitochondrial dysfunction and cell death worsen outcomes after revascularization in ischemic stroke. Receptor-interacting protein kinase 1 (RIPK1) activated dynamin-related protein 1 (DRP1) in a NLRPyrin domain containing 3 (NLRP3) inflammasome-dependent fashion and Hypoxia-Inducible Factor (HIF)-1α play key roles in the process. This study determined how phenothiazine drugs (chlorpromazine and promethazine (C + P)) with the hypothermic and normothermic modality impacts the RIPK1/RIPK3-DRP1 and HIF-1α pathways in providing neuroprotection.

METHODS

A total of 150 adult male Sprague-Dawley rats were subjected to 2 h middle cerebral artery occlusion (MCAO) followed by 24 h reperfusion. 8 mg/kg of C + P was administered at onset of reperfusion. Infarct volumes, mRNA and protein expressions of HIF-1α, RIPK1, RIPK3, DRP-1, NLRP3-inflammation and cytochrome c-apoptosis were assessed. Apoptotic cell death, infiltration of neutrophils and macrophages, and mitochondrial function were evaluated. Interaction between RIPK1/RIPK3 and HIF-1α/NLRP3 were determined. In SH-SY5Y cells subjected to oxygen/glucose deprivation (OGD), the normothermic effect of C + P on inflammation and apoptosis were examined.

RESULTS

C + P significantly reduced infarct volumes, mitochondrial dysfunction (ATP and ROS concentration, citrate synthase and ATPase activity), inflammation and apoptosis with and without induced hypothermia. Overexpression of RIPK1, RIPK3, DRP-1, NLRP3-inflammasome and cytochrome c-apoptosis were all significantly reduced by C + P at 33 °C and the RIPK1 inhibitor (Nec1s), suggesting hypothermic effect of C + P via RIPK1/RIPK3-DRP1pathway. When body temperature was maintained at 37 °C, C + P and HIF-1α inhibitor (YC-1) reduced HIF-1α expression, leading to reduction in mitochondrial dysfunction, NLRP3 inflammasome and cytochrome c-apoptosis, as well as the interaction of HIF-1α and NLRP3. These were also evidenced in vitro, indicating a normothermic effect of C + P via HIF-1α.

CONCLUSION

Hypothermic and normothermic neuroprotection of C + P involve different pathways. The normothermic effect was mediated by HIF-1α, while hypothermic effect was via RIPK1/RIPK3-DRP1 signaling. This provides a theoretical basis for future precise exploration of hypothermic and normothermic neuroprotection.

Unveiling an oxidative stress-linked diagnostic signature and molecular subtypes in preeclampsia: novel insights into pathogenesis

Preeclampsia (PE) is a complex pregnancy disorder characterized by hypertension and organ dysfunction, affecting both maternal and fetal health. Oxidative stress has been implicated in the pathogenesis of PE, but the underlying molecular mechanisms remain poorly understood. In this study, we aimed to identify a diagnostic signature and molecular subtypes associated with oxidative stress in PE to gain novel insights into its pathogenesis. The ssGSEA algorithm evaluated oxidative stress-related pathway scores using transcriptional data from the GSE75010 dataset. Oxidative stress-related genes (ORGs) were co lected from these pathways, and hub ORGs associated with PE were identified using the LASSO and logistic regression models. A nomogram prediction model was constructed using the identified ORGs. Consensus clustering identified two molecular subgroups related to oxidative stress, labeled as C1 and C2, with unique immune characteristics and inflammatory pathway profiles. Seventy ORGs associated with oxidative stress, ce l death, and inflammation-related pathways were identified in PE. EGFR, RIPK3, and ALAD were confirmed as core ORGs for PE biomarkers. The C1 and C2 subgroups exhibited distinct immune characteristics and inflammatory pathway profiles. This study provides novel insights into the role of oxidative stress in PE pathogenesis. A diagnostic signature and molecular subtypes associated with oxidative stress were identified, which may improve understanding, diagnosis, and management of PE.

Immunogenic cell death in cancer: targeting necroptosis to induce antitumour immunity

Most metastatic cancers remain incurable due to the emergence of apoptosis-resistant clones, fuelled by intratumour heterogeneity and tumour evolution. To improve treatment, therapies should not only kill cancer cells but also activate the immune system against the tumour to eliminate any residual cancer cells that survive treatment. While current cancer therapies rely heavily on apoptosis - a largely immunologically silent form of cell death - there is growing interest in harnessing immunogenic forms of cell death such as necroptosis. Unlike apoptosis, necroptosis generates second messengers that act on immune cells in the tumour microenvironment, alerting them of danger. This lytic form of cell death optimizes the provision of antigens and adjuvanticity for immune cells, potentially boosting anticancer treatment approaches by combining cellular suicide and immune response approaches. In this Review, we discuss the mechanisms of necroptosis and how it activates antigen-presenting cells, drives cross-priming of CD8+ T cells and induces antitumour immune responses. We also examine the opportunities and potential drawbacks of such strategies for exposing cancer cells to immunological attacks.

HIST3H2A promotes the progression of prostate cancer through inhibiting cell necroptosis

In recent years, there has been an increase in the incidence and mortality rates of prostate cancer (PCa). However, the specific molecular mechanisms underlying its occurrence and development remain unclear, necessitating the identification of new therapeutic targets. Through bioinformatics analysis, we discovered a previously unstudied differential gene called HIST3H2A in prostate cancer. Our study revealed that HIST3H2A is highly expressed in PCa tissues, as confirmed by analysis of both the GEO and UALCAN databases. Further analysis using the KEGG database demonstrated that HIST3H2A regulates the pathway of programmed necroptosis in cells. Additionally, we observed significant up-regulation of HIST3H2A in PCa tissues and cell lines. HIST3H2A was found to regulate cell proliferation, migration, invasion, and the epithelial-mesenchymal transition (EMT) process in tumors. Notably, HIST3H2A's role in regulating programmed necroptosis in prostate cancer cells differs from its role in apoptosis. In vitro and in vivo experiments collectively support the key role of HIST3H2A in promoting the development of prostate cancer, highlighting its potential as a therapeutic target for patients with PCa.

RIPK3 signaling and its role in regulated cell death and diseases

Receptor-interacting protein kinase 3 (RIPK3), a member of the receptor-interacting protein kinase (RIPK) family with serine/threonine protein kinase activity, interacts with RIPK1 to generate necrosomes, which trigger caspase-independent programmed necrosis. As a vital component of necrosomes, RIPK3 plays an indispensable role in necroptosis, which is crucial for human life and health. In addition, RIPK3 participates in the pathological process of several infections, aseptic inflammatory diseases, and tumors (including tumor-promoting and -suppressive activities) by regulating autophagy, cell proliferation, and the metabolism and production of chemokines/cytokines. This review summarizes the recent research progress of the regulators of the RIPK3 signaling pathway and discusses the potential role of RIPK3/necroptosis in the aetiopathogenesis of various diseases. An in-depth understanding of the mechanisms and functions of RIPK3 may facilitate the development of novel therapeutic strategies.

Mechanisms of chondrocyte regulated cell death in osteoarthritis: Focus on ROS-triggered ferroptosis, parthanatos, and oxeiptosis

Osteoarthritis (OA) is a common chronic inflammatory degenerative disease. Since chondrocytes are the only type of cells in cartilage, their survival is critical for maintaining cartilage morphology. This review offers a comprehensive analysis of how reactive oxygen species (ROS), including superoxide anions, hydrogen peroxide, hydroxyl radicals, nitric oxide, and their derivatives, affect cartilage homeostasis and trigger several novel modes of regulated cell death, including ferroptosis, parthanatos, and oxeiptosis, which may play roles in chondrocyte death and OA development. Moreover, we discuss potential therapeutic strategies to alleviate OA by scavenging ROS and provide new insight into the research and treatment of the role of regulated cell death in OA.

NR4A1 depletion inhibits colorectal cancer progression by promoting necroptosis via the RIG-I-like receptor pathway

Necroptosis is a regulated necrotic cell death mechanism and plays a crucial role in the progression of cancers. However, the potential role and mechanism of necroptosis in colorectal cancer (CRC) has not been fully elucidated. In this study, we found that nuclear receptor subfamily 4 group A member 1 (NR4A1) was highly expressed in CRC cells treated with TNF-α, Smac mimetic, and z-VAD-FMK (TSZ). The depletion of NR4A1 significantly enhanced the sensitivity of CRC cells to TSZ-induced necroptosis, while NR4A1 overexpression suppressed these effects, as evidenced by the LDH assay, flow cytometry analysis of cell death, PI staining, and expression analysis of necrosome complexes (RIPK1, RIPK3, and MLKL). Moreover, NR4A1 deficiency made HT29 xenograft tumors sensitive to necroptotic cell death in vivo. Mechanistically, NR4A1 depletion promoted necroptosis activation in CRC through the RIG-I-like receptor pathway by interacting with DDX3. Importantly, the RIG-I pathway agonist poly(I:C) or inhibitor cFP abolished the effects of NR4A1 overexpression or suppression on necroptosis in CRC cells. Moreover, we observed that NR4A1 was highly expressed in CRC tissues and was associated with a poor prognosis. In conclusion, our results suggest that NR4A1 plays a critical role in modulating necroptosis in CRC cells and provide a new therapeutic target for CRC.

RIP3 in Necroptosis: Underlying Contributions to Traumatic Brain Injury

Traumatic brain injury (TBI) is a global public safety issue that poses a threat to death, characterized by high fatality rates, severe injuries and low recovery rates. There is growing evidence that necroptosis regulates the pathophysiological processes of a variety of diseases, particularly those affecting the central nervous system. Thus, moderate necroptosis inhibition may be helpful in the management of TBI. Receptor-interacting protein kinase (RIP) 3 is a key mediator in the necroptosis, and its absence helps restore the microenvironment at the injured site and improve cognitive impairment after TBI. In this report, we review different domains of RIP3, multiple analyses of necroptosis, and associations between necroptosis and TBI, RIP3, RIP1, and mixed lineage kinase domain-like. Next, we elucidate the potential involvement of RIP3 in TBI and highlight how RIP3 deficiency enhances neuronal function.

RIPK3 promotes islet amyloid-induced β-cell loss and glucose intolerance in a humanized mouse model of type 2 diabetes

OBJECTIVE

Aggregation of human islet amyloid polypeptide (hIAPP), a β-cell secretory product, leads to islet amyloid deposition, islet inflammation and β-cell loss in type 2 diabetes (T2D), but the mechanisms that underlie this process are incompletely understood. Receptor interacting protein kinase 3 (RIPK3) is a pro-death signaling molecule that has recently been implicated in amyloid-associated brain pathology and β-cell cytotoxicity. Here, we evaluated the role of RIPK3 in amyloid-induced β-cell loss using a humanized mouse model of T2D that expresses hIAPP and is prone to islet amyloid formation.

METHODS

We quantified amyloid deposition, cell death and caspase 3/7 activity in islets isolated from WT, Ripk3-/-, hIAPP and hIAPP; Ripk3-/- mice in real time, and evaluated hIAPP-stimulated inflammation in WT and Ripk3-/- bone marrow derived macrophages (BMDMs) in vitro. We also characterized the role of RIPK3 in glucose stimulated insulin secretion (GSIS) in vitro and in vivo. Finally, we examined the role of RIPK3 in high fat diet (HFD)-induced islet amyloid deposition, β-cell loss and glucose homeostasis in vivo.

RESULTS

We found that amyloid-prone hIAPP mouse islets exhibited increased cell death and caspase 3/7 activity compared to amyloid-free WT islets in vitro, and this was associated with increased RIPK3 expression. hIAPP; Ripk3-/- islets were protected from amyloid-induced cell death compared to hIAPP islets in vitro, although amyloid deposition and caspase 3/7 activity were not different between genotypes. We observed that macrophages are a source of Ripk3 expression in isolated islets, and that Ripk3-/- BMDMs were protected from hIAPP-stimulated inflammatory gene expression (Tnf, Il1b, Nos2). Following 52 weeks of HFD feeding, islet amyloid-prone hIAPP mice exhibited impaired glucose tolerance and decreased β-cell area compared to WT mice in vivo, whereas hIAPP; Ripk3-/- mice were protected from these impairments.

CONCLUSIONS

In conclusion, loss of RIPK3 protects from amyloid-induced inflammation and islet cell death in vitro and amyloid-induced β-cell loss and glucose intolerance in vivo. We propose that therapies targeting RIPK3 may reduce islet inflammation and β-cell loss and improve glucose homeostasis in the pathogenesis of T2D.

Study of Therapeutic Mechanisms of Bupi Yichang Formula against Colon Cancer Based on Network Pharmacology, Machine Learning, and Experimental Verification

Bupi Yichang formula (BPYCF) has shown the anti-cancer potential; however, its effects on colon cancer and the mechanisms remain unknown. This study intended to explore the effects of BPYC on colon cancer and its underlying mechanisms. BPYCF-related and colon cancer-related targets were acquired from public databases, followed by differentially expressed genes (DEG) identification. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed using clusterProfiler. A protein-protein interaction (PPI) network was constructed using STRING database. CytoHubba and MCODE to screen the hub targets. A diagnostic model was built using random forest algorithm. Molecular docking was conducted using PyMOL and AutoDock. High-performance liquid chromatograph-mass spectrometry (HPLC-MS) analysis and in vitro validation were performed. Forty-six overlapping targets of BPYCF-related, colon cancer-related targets, and DEGs were obtained. GO and KEGG analyses showed that the targets were mainly enriched in response to lipopolysaccharide, neuronal cell body, protein serine/threonine/tyrosine, as well as C-type lectin receptor, NOD-like receptor, and TNF signaling pathways. Five targets were identified as the pivotal targets, among which, NOS3, CASP8, RIPK3, and TNFRSF10B were stably docked with the core active component, naringenin. Naringenin was also identified from the BPYCF sample through HPLC-MS analysis. In vitro experiments showed that BPYCF inhibited cell viability, reduced NOS3 expression, and elevated CASP8, RIPK3, and TNFRSF10B expression in colon cancer cells. BPYCF might treat colon cancer mainly by regulating NOS3, CASP8, RIPK3, and TN-FRSF10B. This study first revealed the therapeutic effects and mechanisms of BPYCF against colon cancer, paving the path for the development of targeted therapeutic strategies for this cancer in the clinic.

Receptor-interacting protein kinase 2 is associated with tumor immune infiltration, immunotherapy-related biomarkers, and affects gastric cancer cells growth in vivo

Background: The objective of this study was to analyze the research trend of four RIPK genes (RIPK1, RIPK2, RIPK3, and RIPK4), their expression variations in tumors, and the correlation between RIPK2 expression and immune-related biomarkers in gastric cancer (GC). Methods: The PubMed database was utilized to investigate the research trend surrounding four RIPKs genes in tumors. The ULCAN database was employed to analyze the differential expression of these four RIPKs genes. TCGA data were utilized to examine the association between RIPK2 expression and various factors including tumor immune infiltration and immune-related biomarkers. Lastly, the impact of targeting RIPK2 on the growth of GC cells was confirmed through tumor formation assay, immunohistochemistry, and Tunnel assays. Results: In the field of tumor biology, there has been a sustained increase in research focused on the four RIPKs genes over the past decade. Four RIPKs genes are differentially expressed in a majority of tumors. Furthermore, this investigation has unveiled a connection between the expression of RIPK2 and the infiltration of four immune cells, as well as the presence of RNA methylation modifying enzymes, specifically m1A, m6A, and m5C, in GC. Additionally, RIPK2 expression was associated with the genes related to immune checkpoint regulation, as well as genes associated with immunoinhibitors and immunostimulators. It was also revealed that RIPK2 expression was correlated to immunotherapy response biomarkers, namely MSI and TMB, and tumor stemness. Ultimately, it was demonstrated that targeting the RIPK2 effectively regulated GC cells growth through the suppression of PCNA expression and the induction of apoptosis. Conclusion: The expression of RIPK2 is correlated with immune cell infiltration, RNA methyltransferase activity, tumor stemness, checkpoint-related genes, and immunotherapy-related biomarkers. Suppression of RIPK2 impedes the growth of GC cells in vivo. Consequently, RIPK2 holds promise as a viable immunotherapy target for various types of cancer.

ABIN1 (Q478) is Required to Prevent Hematopoietic Deficiencies through Regulating Type I IFNs Expression

A20-binding inhibitor of NF-κB activation (ABIN1) is a polyubiquitin-binding protein that regulates cell death and immune responses. Although Abin1 is located on chromosome 5q in the region commonly deleted in patients with 5q minus syndrome, the most distinct of the myelodysplastic syndromes (MDSs), the precise role of ABIN1 in MDSs remains unknown. In this study, mice with a mutation disrupting the polyubiquitin-binding site (Abin1Q478H/Q478H ) is generated. These mice develop MDS-like diseases characterized by anemia, thrombocytopenia, and megakaryocyte dysplasia. Extramedullary hematopoiesis and bone marrow failure are also observed in Abin1Q478H/Q478H mice. Although Abin1Q478H/Q478H cells are sensitive to RIPK1 kinase-RIPK3-MLKL-dependent necroptosis, only anemia and splenomegaly are alleviated by RIPK3 deficiency but not by MLKL deficiency or the RIPK1 kinase-dead mutation. This indicates that the necroptosis-independent function of RIPK3 is critical for anemia development in Abin1Q478H/Q478H mice. Notably, Abin1Q478H/Q478H mice exhibit higher levels of type I interferon (IFN-I) expression in bone marrow cells compared towild-type mice. Consistently, blocking type I IFN signaling through the co-deletion of Ifnar1 greatly ameliorated anemia, thrombocytopenia, and splenomegaly in Abin1Q478H/Q478H mice. Together, these results demonstrates that ABIN1(Q478) prevents the development of hematopoietic deficiencies by regulating type I IFN expression.

Dichotomous roles of RIPK3 in regulating the IFN response and NLRP3 inflammasome in human monocytes

Regulation of the profile and magnitude of toll-like receptor (TLR) responses is important for effective host defense against infections while minimizing inflammatory toxicity. The chemokine CXCL4 regulates the TLR8 response to amplify inflammatory gene and inflammasome activation while attenuating the interferon (IFN) response in primary monocytes. In this study, we describe an unexpected role for the kinase RIPK3 in suppressing the CXCL4 + TLR8-induced IFN response and providing signal 2 to activate the NLRP3 inflammasome and interleukin (IL)-1 production in primary human monocytes. RIPK3 also amplifies induction of inflammatory genes such as TNF, IL6, and IL1B while suppressing IL12B. Mechanistically, RIPK3 inhibits STAT1 activation and activates PI3K-Akt-dependent and XBP1- and NRF2-mediated stress responses to regulate downstream genes in a dichotomous manner. These findings identify new functions for RIPK3 in modulating TLR responses and provide potential mechanisms by which RIPK3 plays roles in inflammatory diseases and suggest targeting RIPK3 and XBP1- and NRF2-mediated stress responses as therapeutic strategies to suppress inflammation while preserving the IFN response for host defense.

Macrophage RIPK3 triggers inflammation and cell death via the XBP1-Foxo1 axis in liver ischaemia-reperfusion injury

Background & Aims

Receptor-interacting serine/threonine-protein kinase 3 (RIPK3) is a central player in triggering necroptotic cell death. However, whether macrophage RIPK3 may regulate NOD1-dependent inflammation and calcineurin/transient receptor potential cation channel subfamily M member 7 (TRPM7)-induced hepatocyte death in oxidative stress-induced liver inflammatory injury remains elusive.

Methods

A mouse model of hepatic ischaemia-reperfusion (IR) injury, the primary hepatocytes, and bone marrow-derived macrophages were used in the myeloid-specific RIPK3 knockout (RIPK3M-KO) and RIPK3-proficient (RIPK3FL/FL) mice.

Results

RIPK3M-KO diminished IR stress-induced liver damage with reduced serum alanine aminotransferase/aspartate aminotransferase levels, macrophage/neutrophil infiltration, and pro-inflammatory mediators compared with the RIPK3FL/FL controls. IR stress activated RIPK3, inositol-requiring transmembrane kinase/endoribonuclease 1α (IRE1α), x-box binding protein 1 (XBP1), nucleotide-binding oligomerisation domain-containing protein 1 (NOD1), NF-κB, forkhead box O1 (Foxo1), calcineurin A, and TRPM7 in ischaemic livers. Conversely, RIPK3M-KO depressed IRE1α, XBP1, NOD1, calcineurin A, and TRPM7 activation with reduced serum tumour necrosis factor α (TNF-α) levels. Moreover, Foxo1M-KO alleviated IR-induced liver injury with reduced NOD1 and TRPM7 expression. Interestingly, chromatin immunoprecipitation coupled with massively parallel sequencing revealed that macrophage Foxo1 colocalised with XBP1 and activated its target gene Zc3h15 (zinc finger CCCH domain-containing protein 15). Activating macrophage XBP1 enhanced Zc3h15, NOD1, and NF-κB activity. However, disruption of macrophage Zc3h15 inhibited NOD1 and hepatocyte calcineurin/TRPM7 activation, with reduced reactive oxygen species production and lactate dehydrogenase release after macrophage/hepatocyte coculture. Furthermore, adoptive transfer of Zc3h15-expressing macrophages in RIPK3M-KO mice augmented IR-triggered liver inflammation and cell death.

Conclusions

Macrophage RIPK3 activates the IRE1α-XBP1 pathway and Foxo1 signalling in IR-stress livers. The XBP1-Foxo1 interaction is essential for modulating target gene Zc3h15 function, which is crucial for the control of NOD1 and calcineurin-mediated TRPM7 activation. XBP1 functions as a transcriptional coactivator of Foxo1 in regulating NOD1-driven liver inflammation and calcineurin/TRPM7-induced cell death. Our findings underscore a novel role of macrophage RIPK3 in stress-induced liver inflammation and cell death, implying the potential therapeutic targets in liver inflammatory diseases.

Impact and implications

Macrophage RIPK3 promotes NOD1-dependent inflammation and calcineurin/TRPM7-induced cell death cascade by triggering the XBP1-Foxo1 axis and its target gene Zc3h15, which is crucial for activating NOD1 and calcineurin/TRPM7 function, implying the potential therapeutic targets in stress-induced liver inflammatory injury.

Mitochondrial transplantation strategies in multifaceted induction of cancer cell death

Otto Warburg hypothesized that some cancer cells reprogram their metabolism, favoring glucose metabolism by anaerobic glycolysis (Warburg effect) instead of oxidative phosphorylation, mainly because the mitochondria of these cells were damaged or dysfunctional. It should be noted that mitochondrial apoptosis is decreased because of the dysfunctional mitochondria. Strategies like mitochondrial transplantation therapy, where functional mitochondria are transplanted to cancer cells, could increase cell death, such as apoptosis, because the intrinsic apoptosis mechanisms would be reactivated. In addition, mitochondrial transplantation is associated with the redox state, which could promote synergy with common anticancer treatments such as ionizing radiation, chemotherapy, or radiotherapy, increasing cell death due to the presence or decrease of oxidative stress. On the other hand, mitochondrial transfer, a natural process for sharing mitochondrial between cells, induces an increase in chemoresistance and invasiveness in cancer cells that receive mitochondria from cells of the tumor microenvironment (TME), which indicates an antitumor therapeutic target. This review focuses on understanding mitochondrial transplantation as a therapeutic outcome induced by a procedure in aspects including oxidative stress, metabolism shifting, mitochondrial function, auto-/mitophagy, invasiveness, and chemoresistance. It also explores how these mechanisms, such as apoptosis, necroptosis, and parthanatos, impact cell death pathways. Finally, it discusses the chemoresistance and invasiveness in cancer cells associated with mitochondria transfer, indicating an antitumor therapeutic target.

Molecular mechanism by which RRM2-inhibitor (cholagogue osalmid) plus bafilomycin A1 cause autophagic cell death in multiple myeloma

Despite significant improvement in the prognosis of multiple myeloma (MM), the disease remains incurable; thus, more effective therapies are required. Ribonucleoside-diphosphate reductase subunit M2 (RRM2) is significantly associated with drug resistance, rapid relapse, and poor prognosis. Previously, we found that 4-hydroxysalicylanilide (osalmid), a specific inhibitor of RRM2, exhibits anti-MM activity in vitro, in vivo, and in human patients; however, the mechanism remains unclear. Osalmid inhibits the translocation of RRM2 to the nucleus and stimulates autophagosome synthesis but inhibits subsequent autophagosome-lysosome fusion. We confirm that RRM2 binds to receptor-interacting protein kinase 3 (RIPK3) and reduces RIPK3, inhibiting autophagosome-lysosome fusion. Interestingly, the combination of osalmid and bafilomycin A1 (an autophagy inhibitor) depletes RIPK3 and aggravates p62 and autophagosome accumulation, leading to autophagic cell death. Combination therapy demonstrates synergistic cytotoxicity both in vitro and in vivo. Therefore, we propose that combining osalmid and bafilomycin A1(BafA1) may have clinical benefits against MM.

Identification and validation of a necroptosis-related gene prognostic signature for colon adenocarcinoma

Background

Necroptosis is a novel programmed cell death pathway proposed in 2005, which is mainly activated by the tumor necrosis factor (TNF) family and mediates cellular disassembly via receptor interacting serine/threonine kinase 1 (RIPK1), receptor interacting serine/threonine kinase 3 (RIPK3) and mixed lineage kinase domain like pseudokinase (MLKL). We tried to analyze the relationship of necroptosis-related genes (NRGs) expression with colon adenocarcinoma (COAD) and propose potential therapeutic targets through immunological analysis.

Methods

First, we evaluated the expression of NRGs in COAD patients and constructed a prognostic signature. The prognostic signature was validated using The Cancer Genome Atlas (TCGA)-COAD and GSE39582 datasets, respectively. And the Kaplan-Meier analysis, receiver operating characteristic (ROC) curves, and principal component analysis were used to evaluate the signature. Then we analyzed the enrichment of NRGs in the signature using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Finally, we analyzed the immunological characteristics of the COAD patients by single sample gene set enrichment analysis (ssGSEA) and predicted the possible immune checkpoints.

Results

We constructed a prognostic signature with 8 NRGs (RIPK3, MLKL, TRAF2, CXCL1, RBCK1, CDKN2A, JMJD7-PLA2G4B and CAMK2B). The Kaplan-Meier analysis, ROC curves, and principal component analysis demonstrated good predictivity of the signature. In addition, we constructed a nomogram with good individualized predictive ability (C-index =0.772). The immunological analysis revealed that the prognosis of COAD was associated with autoimmune function, and we proposed 10 potential therapeutic targets.

Conclusions

Overall, we constructed an NRGs prognostic signature and suggested potential therapeutic targets for the COAD treatment.

Targeted splicing therapy: new strategies for colorectal cancer

RNA splicing is the process of forming mature mRNA, which is an essential phase necessary for gene expression and controls many aspects of cell proliferation, survival, and differentiation. Abnormal gene-splicing events are closely related to the development of tumors, and the generation of oncogenic isoform in splicing can promote tumor progression. As a main process of tumor-specific splicing variants, alternative splicing (AS) can promote tumor progression by increasing the production of oncogenic splicing isoforms and/or reducing the production of normal splicing isoforms. This is the focus of current research on the regulation of aberrant tumor splicing. So far, AS has been found to be associated with various aspects of tumor biology, including cell proliferation and invasion, resistance to apoptosis, and sensitivity to different chemotherapeutic drugs. This article will review the abnormal splicing events in colorectal cancer (CRC), especially the tumor-associated splicing variants arising from AS, aiming to offer an insight into CRC-targeted splicing therapy.

Reverse-ChIP Techniques for Identifying Locus-Specific Proteomes: A Key Tool in Unlocking the Cancer Regulome

A phenotypic hallmark of cancer is aberrant transcriptional regulation. Transcriptional regulation is controlled by a complicated array of molecular factors, including the presence of transcription factors, the deposition of histone post-translational modifications, and long-range DNA interactions. Determining the molecular identity and function of these various factors is necessary to understand specific aspects of cancer biology and reveal potential therapeutic targets. Regulation of the genome by specific factors is typically studied using chromatin immunoprecipitation followed by sequencing (ChIP-Seq) that identifies genome-wide binding interactions through the use of factor-specific antibodies. A long-standing goal in many laboratories has been the development of a 'reverse-ChIP' approach to identify unknown binding partners at loci of interest. A variety of strategies have been employed to enable the selective biochemical purification of sequence-defined chromatin regions, including single-copy loci, and the subsequent analytical detection of associated proteins. This review covers mass spectrometry techniques that enable quantitative proteomics before providing a survey of approaches toward the development of strategies for the purification of sequence-specific chromatin as a 'reverse-ChIP' technique. A fully realized reverse-ChIP technique holds great potential for identifying cancer-specific targets and the development of personalized therapeutic regimens.

Epigenetic changes induced by pathogenic Chlamydia spp

Chlamydia trachomatis, C. pneumoniae, and C. psittaci, the three Chlamydia species known to cause human disease, have been collectively linked to several pathologies, including conjunctivitis, trachoma, respiratory disease, acute and chronic urogenital infections and their complications, and psittacosis. In vitro, animal, and human studies also established additional correlations, such as between C. pneumoniae and atherosclerosis and between C. trachomatis and ovarian cancer. As part of their survival and pathogenesis strategies as obligate intracellular bacteria, Chlamydia spp. modulate all three major types of epigenetic changes, which include deoxyribonucleic acid (DNA) methylation, histone post-translational modifications, and microRNA-mediated gene silencing. Some of these epigenetic changes may be implicated in key aspects of pathogenesis, such as the ability of the Chlamydia spp. to induce epithelial-to-mesenchymal transition, interfere with DNA damage repair, suppress cholesterol efflux from infected macrophages, act as a co-factor in human papillomavirus (HPV)-mediated cervical cancer, prevent apoptosis, and preserve the integrity of mitochondrial networks in infected host cells. A better understanding of the individual and collective contribution of epigenetic changes to pathogenesis will enhance our knowledge about the biology of Chlamydia spp. and facilitate the development of novel therapies and biomarkers. Pathogenic Chlamydia spp. contribute to epigenetically-mediated gene expression changes in host cells by multiple mechanisms.

Renal tubular epithelial cell necroptosis promotes tubulointerstitial fibrosis in patients with chronic kidney disease

Renal fibrosis, a common pathological manifestation of virtually all types of chronic kidney disease (CKD), ultimately predisposes patients to end-stage renal disease. However, there is no effective therapy for renal fibrosis. Our earlier studies proved that RIP3-mediated necroptosis might be an important mode of renal tubular cell death in rats with chronic renal injury. Under transmission electron microscopy (TEM), we found morphological changes in the necrosis of human renal tissue, and the percentage of necrotic cells increased significantly in patients with stages 2 and 3a CKD. Immunofluorescence analyses showed that the percentages of TUNEL⁺ /RIP3⁺ double-positive and TUNEL⁺ /MLKL⁺ double-positive tubular epithelial cells in renal tubules of patients with stages 2 and 3a CKD were significantly increased compared to those in control patients without renal disease. Immunohistochemistry analyses of renal biopsy specimens from patients with CKD revealed RIP3, MLKL, and p-MLKL upregulation in patients with stages 2 and 3a CKD, suggesting that necroptosis of renal tubular epithelial cells in CKD patients occurs, and the peak of necroptosis was in stages 2 and 3a CKD. We showed that profibrotic factor proteins (TGF-β1, Smad2 and Smad3) and fibroblast activation markers (α-SMA and Vimentin) were specifically upregulated in stage 2 and 3a CKD patients. In addition, Pearson correlation analysis showed that the percentage of necroptotic renal tubular epithelial cells was positively correlated with TGF-β1 and collagen-I. We also showed that RIP1/3 or MLKL inhibitors decreased the expression of RIP3, MLKL, TGF-β1, and Smad3 in HK-2 cells treated with TNF-α. FGF-2, α-SMA, Vimentin and FN were overexpressed in the hRIFs cultured with the supernatant of necroptotic HK-2 cells, whereas necroptosis blockers (Nec-1s, GSK'872 and NSA) and TGF-β1/Smad3 pathway antagonists (LY364947 and SIS3) reduced FGF-2, α-SMA, Vimentin and FN levels. Collectively, necroptosis of renal tubular epithelial cells in CKD patients occurs, and the peak of necroptosis was in stages 2 and 3a CKD. Renal tubular epithelial cell necroptosis mediates renal tubulointerstitial fibrosis in patients with chronic kidney disease, which is related to the TGF-β1/Smad3 signaling pathway.

Prognosis analysis of necroptosis-related genes in colorectal cancer based on bioinformatic analysis

Background: Colorectal cancer (CRC) is one gastrointestinal malignancy, accounting for 10% of cancer diagnoses and cancer-related deaths worldwide each year. Therefore, it is urgent to identify genes involved in CRC predicting the prognosis.

Methods: CRC’s data were acquired from the Gene Expression Omnibus (GEO) database (GSE39582 and GSE41258 datasets) and The Cancer Genome Atlas (TCGA) database. The differentially expressed necroptosis-related genes (DENRGs) were sorted out between tumor and normal tissues. Univariate Cox regression analysis and least absolute shrinkage and selectionator operator (LASSO) analysis were applied to selected DENRGs concerning patients’ overall survival and to construct a prognostic biomarker. The effectiveness of this biomarker was assessed by the Kaplan–Meier curve and the receiver operating characteristic (ROC) analysis. The GSE39582 dataset was utilized as external validation for the prognostic signature. Moreover, using univariate and multivariate Cox regression analyses, independent prognostic factors were identified to construct a prognostic nomogram. Next, signaling pathways regulated by the signature were explored through the gene set enrichment analysis (GSEA). The single sample gene set enrichment analysis (ssGSEA) algorithm and tumor immune dysfunction and exclusion (TIDE) were used to explore immune correlation in the two groups, high-risk and low-risk ones. Finally, prognostic genes’ expression was examined in the GSE41258 dataset.

Results: In total, 27 DENRGs were filtered, and a necroptosis-related prognostic signature based on 6 DENRGs was constructed, which may better understand the overall survival (OS) of CRC. The Kaplan–Meier curve manifested the effectiveness of the prognostic signature, and the ROC curve showed the same result. In addition, univariate and multivariate Cox regression analyses revealed that age, pathology T, and risk score were independent prognostic factors, and a nomogram was established. Furthermore, the prognostic signature was most significantly associated with the apoptosis pathway. Meanwhile, 24 immune cells represented significant differences between two groups, like the activated B cell. Furthermore, 32 immune checkpoints, TIDE scores, PD-L1 scores, and T-cell exclusion scores were significantly different between the two groups. Finally, a 6-gene prognostic signature represented different expression levels between tumor and normal samples significantly in the GSE41258 dataset.

Conclusion: Our study established a signature including 6 genes and a prognostic nomogram that could significantly assess the prognosis of patients with CRC.

Necroptosis-Related Genes Associated With Immune Activity and Prognosis of Colorectal Cancer

This study aims at screening out the key necroptosis-related genes in colorectal cancer and elucidating the role of necroptosis-related genes in the immune activity and prognosis of colorectal cancer (CRC). The CRC patients’ data were downloaded from The Cancer Genome Atlas (TCGA). The non-negative matrix factorization method was applied to identify new molecular subgroups. Survival analysis and single sample Gene Set Enrichment Analysis were performed to determinate the differences in the overall survival time and immune status of the subgroups. Prognostic model was constructed on the basis of univariate Cox regression and LASSO analysis. Functional analyses were used to explore the potential mechanisms. Based on prognostic related necroptosis genes, we identify two molecular subgroups with significantly different survival. The better prognosis was associated with more active immune infiltration and upregulated expression of immune checkpoints. We screened nine necroptosis related genes as key prognostic genes and established a risk model, which showed a good potential for survival prediction in colorectal cancer. Nomogram assessment showed that the model had high reliability for predicting the prognosis of colorectal cancer patients. The high-risk and low-risk group also has different sensitivity to immunotherapy and commonly used drugs for colorectal cancer. Overall, necroptosis related genes were involved in the immune microenvironment of colorectal cancer patient, could be utilized to predict the prognosis of colorectal cancer and develop more individualized treatment.

MLKL deficiency in BrafV600EPten−/− melanoma model results in a modest delay of nevi development and reduced lymph node dissemination in male mice

Cancers acquire several capabilities to survive the multistep process in carcinogenesis. Resisting cell death is one of them. Silencing of the necroptosis initiator Ripk3 occurs in a wide variety of cancer types including melanoma. Little is known about the role of the necroptosis executioner MLKL in tumor development. Studies often indicate opposing roles for MLKL as a tumor-suppressing or a tumor-promoting protein. This study investigates the role of MLKL during melanoma initiation and progression using a tamoxifen-inducible melanoma mouse model driven by melanocyte-specific overexpression of mutated Braf and simultaneous deletion of Pten (Braf^V600EPten^−/−). In this model we observed a clear sex difference: melanoma initiation and progression were faster in females mice. Mlkl deficiency in male mice resulted in a modest but significant reduction of nevi growth rate compared to the littermate control. In these mice, infiltration and expansion of melanoma cells in the inguinal lymph node were also modestly decreased. This is likely to be a consequence of the delay in nevi development. No significant difference was observed in the Mlkl-deficient condition in female mice in which melanoma development was faster. Overall, our results indicate that in this genetic model MLKL has a minor role during melanoma initiation and progression.