A novel small molecule Hsp90 inhibitor, C-316-1, attenuates acute kidney injury by suppressing RIPK1-mediated inflammation and necroptosis

HSPA12A stimulates "Smurf1-Hif1α-aerobic glycolysis" axis to promote proliferation of renal tubular epithelial cells after hypoxia/reoxygenation injury

Proliferation of renal tubular epithelial cells (TECs) is critical for the recovery after kidney ischemia/reperfusion (KI/R). However, there is still a lack of ideal therapies for promoting TEC proliferation. Heat shock protein A12A (HSPA12A) shows abundant expression in kidney in our previous studies. To investigate the role of HSPA12A in TEC proliferation after KI/R, an in vitro KI/R model was simulated by hypoxia (12 h) and reoxygenation (12 h) in human kidney tubular epithelial HK-2 cells. We found that, when hypoxia/reoxygenation (H/R) triggered HK-2 cell injury, HSPA12A expression was downregulated, and extracellular lactate, the readout of glycolysis, was also decreased. Loss and gain of functional studies showed that HSPA12A did not change cell viability after hypoxia but increased cell proliferation as well as glycolytic flux of HK-2 cells after H/R. When blocking glycolysis by 2-deoxy-D-glucose or oxamate, the HSPA12A promoted HK-2 cell proliferation was also abolished. Further analysis revealed that HSPA12A overexpression increased hypoxia-inducible factor 1α (Hif1α) protein expression and nuclear localization in HK-2 cells in response to H/R, whereas HSPA12A knockdown showed the opposite effects. Notably, pharmacological inhibition of Hif1α with YC-1 reversed the HSPA12A-induced increases of both glycolytic flux and proliferation of H/R HK-2 cells. Moreover, the HSPA12A increased Hif1α protein expression was not via upregulating its transcription but through increasing its protein stability in a Smurf1-dependent manner. The findings indicate that HSPA12A might serve as a promising target for TEC proliferation to help recovery after KI/R.

Small molecule inhibitors targeting heat shock protein 90: An updated review

As a molecular chaperone, heat shock protein 90 (HSP90) plays important roles in the folding, stabilization, activation, and degradation of over 500 client proteins, and is extensively involved in cell signaling, proliferation, and survival. Thus, it has emerged as an important target in a variety of diseases, including cancer, neurodegenerative diseases, and viral infections. Therefore, targeted inhibition of HSP90 provides a valuable and promising therapeutic strategy for the treatment of HSP90-related diseases. This review aims to systematically summarize the progress of research on HSP90 inhibitors in the last five years, focusing on their structural features, design strategies, and biological activities. It will refer to the natural products and their derivatives (including novobiocin derivatives, deguelin derivatives, quinone derivatives, and terpenoid derivatives), and to synthetic small molecules (including resorcinol derivatives, pyrazoles derivatives, triazole derivatives, pyrimidine derivatives, benzamide derivatives, benzothiazole derivatives, and benzofuran derivatives). In addition, the major HSP90 small-molecule inhibitors that have moved into clinical trials to date are also presented here.

Role of gasotransmitters in necroptosis

Gasotransmitters are endogenous gaseous signaling molecules that can freely pass through cell membranes and transmit signals between cells, playing multiple roles in cell signal transduction. Due to extensive and ongoing research in this field, we have successfully identified many gasotransmitters so far, among which nitric oxide, carbon monoxide, and hydrogen sulfide are best studied. Gasotransmitters are implicated in various diseases related to necroptosis, such as cardiovascular diseases, inflammation, ischemia-reperfusion, infectious diseases, and neurological diseases. However, the mechanisms of their effects on necroptosis are not fully understood. This review focuses on endogenous gasotransmitter synthesis and metabolism and discusses their roles in necroptosis, aiming to offer new insights for the therapeutic approaches to necroptosis-associated diseases.

The Role of Necroptosis in Cerebral Ischemic Stroke

Cerebral ischemia, also known as ischemic stroke, accounts for nearly 85% of all strokes and is the leading cause of disability worldwide. Due to disrupted blood supply to the brain, cerebral ischemic injury is trigged by a series of complex pathophysiological events including excitotoxicity, oxidative stress, inflammation, and cell death. Currently, there are few treatments for cerebral ischemia owing to an incomplete understanding of the molecular and cellular mechanisms. Accumulated evidence indicates that various types of programmed cell death contribute to cerebral ischemic injury, including apoptosis, ferroptosis, pyroptosis and necroptosis. Among these, necroptosis is morphologically similar to necrosis and is mediated by receptor-interacting serine/threonine protein kinase-1 and -3 and mixed lineage kinase domain-like protein. Necroptosis inhibitors have been shown to exert inhibitory effects on cerebral ischemic injury and neuroinflammation. In this review, we will discuss the current research progress regarding necroptosis in cerebral ischemia as well as the application of necroptosis inhibitors for potential therapeutic intervention in ischemic stroke.

Decoding ferroptosis: Revealing the hidden assassin behind cardiovascular diseases

The discovery of regulatory cell death processes has driven innovation in cardiovascular disease (CVD) therapeutic strategies. Over the past decade, ferroptosis, an iron-dependent form of regulated cell death driven by excessive lipid peroxidation, has been shown to drive the development of multiple CVDs. This review provides insights into the evolution of the concept of ferroptosis, the similarities and differences with traditional modes of programmed cell death (e.g., apoptosis, autophagy, and necrosis), as well as the core regulatory mechanisms of ferroptosis (including cystine/glutamate transporter blockade, imbalance of iron metabolism, and lipid peroxidation). In addition, it provides not only a detailed review of the role of ferroptosis and its therapeutic potential in widely studied CVDs such as coronary atherosclerotic heart disease, myocardial infarction, myocardial ischemia/reperfusion injury, heart failure, cardiomyopathy, and aortic aneurysm but also an overview of the phenomenon and therapeutic perspectives of ferroptosis in lesser-addressed CVDs such as cardiac valvulopathy, pulmonary hypertension, and sickle cell disease. This article aims to integrate this knowledge to provide a comprehensive view of ferroptosis in a wide range of CVDs and to drive innovation and progress in therapeutic strategies in this field.

The emerging role of regulated cell death in ischemia and reperfusion-induced acute kidney injury: current evidence and future perspectives

Renal ischemia‒reperfusion injury (IRI) is one of the main causes of acute kidney injury (AKI), which is a potentially life-threatening condition with a high mortality rate. IRI is a complex process involving multiple underlying mechanisms and pathways of cell injury and dysfunction. Additionally, various types of cell death have been linked to IRI, including necroptosis, apoptosis, pyroptosis, and ferroptosis. These processes operate differently and to varying degrees in different patients, but each plays a role in the various pathological conditions of AKI. Advances in understanding the underlying pathophysiology will lead to the development of new therapeutic approaches that hold promise for improving outcomes for patients with AKI. This review provides an overview of the recent research on the molecular mechanisms and pathways underlying IRI-AKI, with a focus on regulated cell death (RCD) forms such as necroptosis, pyroptosis, and ferroptosis. Overall, targeting RCD shows promise as a potential approach to treating IRI-AKI.

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.

LncRNA MALAT1 Promoted Neuronal Necroptosis in Cerebral Ischemia-reperfusion Mice by Stabilizing HSP90

The objective of this research was to investigate the role of lncRNA MALAT1 and HSP90 in the regulation of neuronal necroptosis in mice with cerebral ischemia-reperfusion (CIR). We used male C57BL/6J mice to establish a middle cerebral artery occlusion (MCAO) model and conducted in vitro experiments using the HT-22 mouse hippocampal neuron cell line. The cellular localization of NeuN and MLKL, as well as the expression levels of neuronal necroptosis factors, MALAT1, and HSP90 were analyzed. Cell viability and necroptosis were assessed, and we also investigated the relationship between MALAT1 and HSP90. The results showed that MALAT1 expression increased after MCAO and oxygen-glucose deprivation/re-oxygenation (OGD/R) treatment in both cerebral tissues and cells compared with the control group. The levels of neuronal necroptosis factors and the co-localization of NeuN and MLKL were also increased in MCAO mice compared with the Sham group. MALAT1 was found to interact with HSP90, and inhibition of HSP90 expression led to decreased phosphorylation levels of neuronal necroptosis factors. Inhibition of MALAT1 expression resulted in decreased co-localization levels of NeuN and MLKL, decreased phosphorylation levels of neuronal necroptosis factors, and reduced necroptosis rate in cerebral tissues. Furthermore, inhibiting MALAT1 expression also led to a shorter half-life of HSP90, increased ubiquitination level, and decreased phosphorylation levels of neuronal necroptosis factors in cells. In conclusion, this study demonstrated that lncRNA MALAT1 promotes neuronal necroptosis in CIR mice by stabilizing HSP90.

Paeoniflorin protects against cisplatin-induced acute kidney injury through targeting Hsp90AA1-Akt protein-protein interaction

ETHNOPHARMACOLOGICAL RELEVANCE

Paeonia lactiflora Pall has been used in Chinese Medicine for thousands of years, especially having anti-inflammatory, sedative, analgesic and other ethnic pharmacological effects. Moreover, Paeoniflorin is the main active ingredient of the Paeonia lactiflora Pall, and most are used in the treatment of inflammation-related autoimmune diseases. In recent years, studies have found that Paeoniflorin has a therapeutic effect on a variety of kidney diseases.

AIM OF THE STUDY

Cisplatin (CIS) is limited in clinical use due to its serious side effects, such as renal toxicity, and there is no effective method for prevention. Paeoniflorin (Pae) is a natural polyphenol which has a protective effect against many kidney diseases. Therefore, our study is to explore the effect of Pae on CIS-induced AKI and the specific mechanism.

MATERIALS AND METHODS

Firstly, CIS induced acute renal injury model was constructed in vivo and in vitro, and Pae was continuously injected intraperitoneally three days in advance, and then Cr, BUN and renal tissue PAS staining were detected to comprehensively evaluate the protective effect of Pae on CIS-induced AKI. We then combined Network Pharmacology with RNA-seq to investigate potential targets and signaling pathways. Finally, affinity between Pae and core targets was detected by molecular docking, CESTA and SPR, and related indicators were detected in vitro and in vivo.

RESULTS

In this study, we first found that Pae significantly alleviated CIS-AKI in vivo and in vitro. Through network pharmacological analysis, molecular docking, CESTA and SPR experiments, we found that the target of Pae was Heat Shock Protein 90 Alpha Family Class A Member 1 (Hsp90AA1) which performs a crucial function in the stability of many client proteins including Akt. RNA-seq found that the KEGG enriched pathway was PI3K-Akt pathway with the most associated with the protective effect of Pae which is consistent with Network Pharmacology. GO analysis showed that the main biological processes of Pae against CIS-AKI include cellular regulation of inflammation and apoptosis. Immunoprecipitation further showed that pretreatment with Pae promoted the Hsp90AA1-Akt protein-protein Interactions (PPIs). Thereby, Pae accelerates the Hsp90AA1-Akt complex formation and leads to a significant activate in Akt, which in turn reduces apoptosis and inflammation. In addition, when Hsp90AA1 was knocked down, the protective effect of Pae did not continue.

CONCLUSION

In summary, our study suggests that Pae attenuates cell apoptosis and inflammation in CIS-AKI by promoting Hsp90AA1-Akt PPIs. These data provide a scientific basis for the clinical search for drugs to prevent CIS-AKI.

Following the design path of isoform-selective Hsp90 inhibitors: Small differences, great opportunities

The heat shock protein 90 (Hsp90) family consists of four highly conserved isoforms: the mitochondrial TRAP-1, the endoplasmic reticulum-localised Grp94, and the cytoplasmic Hsp90α and Hsp90β. Since the late 1990s, this family has been extensively studied as a potential target for the treatment of cancer, neurological disorders, and infectious diseases. The initial approach was to develop non-selective, so-called pan-Hsp90 ATP-competitive inhibitors of the N-terminal domain. Many of these agents were tested in clinical trials, mainly for the treatment of cancer, but none of them succeeded in the clinic. This was mainly due to the lack of efficacy and various toxicities associated with the induction of heat shock response (HSR). This lack of success has prompted a turn to new approaches of Hsp90 inhibition. Thus, inhibitors selective for a particular isoform of Hsp90 have been developed. These isoform-selective inhibitors do not induce HSR and have a more targeted effect because not all client proteins are equally dependent on all four paralogues of Hsp90. However, it is extremely difficult to develop such selective compounds because the family is highly conserved. Hsp90α and Hsp90β have an amazing 95% identity of the N-terminal ATP binding site, differing only in two amino acid residues. Therefore, the focus of this review is to fully elucidate the key structural features of the selective inhibitor classes in terms of binding site dissimilarities. In addition to a methodological characterisation of the structure-activity relationships, the main advantages of selective inhibition of the TRAP-1, Grp94, Hsp90α and Hsp90β isoforms are discussed.

Autophagy and necroptosis in cisplatin-induced acute kidney injury: Recent advances regarding their role and therapeutic potential

Cisplatin (CP) is a broad-spectrum antineoplastic agent, used to treat many different types of malignancies due to its high efficacy and low cost. However, its use is largely limited by acute kidney injury (AKI), which, if left untreated, may progress to cause irreversible chronic renal dysfunction. Despite substantial research, the exact mechanisms of CP-induced AKI are still so far unclear and effective therapies are lacking and desperately needed. In recent years, necroptosis, a novel subtype of regulated necrosis, and autophagy, a form of homeostatic housekeeping mechanism have witnessed a burgeoning interest owing to their potential to regulate and alleviate CP-induced AKI. In this review, we elucidate in detail the molecular mechanisms and potential roles of both autophagy and necroptosis in CP-induced AKI. We also explore the potential of targeting these pathways to overcome CP-induced AKI according to recent advances.

Cpd-42 protects against calcium oxalate nephrocalcinosis-induced renal injury and inflammation by targeting RIPK3-mediated necroptosis

Calcium oxalate (CaOx) crystals, as the predominant component of human kidney stones, can trigger excessive cell death and inflammation of renal tubular epithelial cells, involved in the pathogenesis of nephrocalcinosis. Necroptosis mediated by receptor-interacting protein kinase 3 (RIPK3) serves a critical role in the cytotoxicity of CaOx crystals. Here, we assessed the therapeutic potential of a novel RIPK3 inhibitor, compound 42 (Cpd-42), for CaOx nephrocalcinosis by comparison with dabrafenib, a classic RIPK3 inhibitor. Our results demonstrated that Cpd-42 pretreatment attenuated CaOx crystals-induced renal tubular epithelial cell (TEC) injury by inhibiting necroptosis and inflammation in vitro and in vivo. Furthermore, in an established mouse model of CaOx nephrocalcinosis, Cpd-42 also reduced renal injury while improving the impaired kidney function and intrarenal crystal deposition. Consistent with this finding, Cpd-42 was confirmed to exhibit superior inhibition of necroptosis and protection against renal TEC injury compared to the classic RIPK3 inhibitor dabrafenib in vitro and in vivo. Mechanistically, RIPK3 knockout (KO) tubular epithelial cells pretreated with Cpd-42 did not show further enhancement of the protective effect on crystals-induced cell injury and inflammation. We confirmed that Cpd-42 exerted protective effects by specifically targeting and inhibiting RIPK3-mediated necroptosis to block the formation of the RIPK1-RIPK3 necrosome. Taken together, targeted inhibition of RIPK3-mediated necroptosis with Cpd-42 may provide a potential therapeutic approach for CaOx nephrocalcinosis.

Agathis robusta Bark Extract Protects from Renal Ischemia-Reperfusion Injury: Phytochemical, In Silico and In Vivo Studies

Background: Acute kidney injury (AKI) induced by renal ischemia-reperfusion injury (RIRI) is associated with a high incidence of mortality. Existing therapies are mainly supportive, with no available nephroprotective agent. The purpose of this study is to examine the potential protective effect of Agathis robusta Bark Extract (ARBE) in RIRI. Methods: The chemical composition of ARBE was examined by LC-ESI-MS/MS. Network pharmacology was utilized to identify the RIRI molecular targets that could be aimed at by the identified major components of ARBE. Experimentally validated protein–protein interactions (PPIs) and compound-target networks were constructed using the STRING database and Cytoscape software. Molecular docking studies were employed to assess the interaction of the most relevant ARBE compounds with the hub RIRI-related targets. Furthermore, ARBE was tested in a rat model of RIRI. Results: The phytochemical analysis identified 95 components in ARBE, 37 of which were majors. Network analysis identified 312 molecular targets of RIRI that were associated with ARBE major compounds. Of these 312, the top targets in the experimentally validated PPI network were HSP90, EGFR, and P53. The most relevant compounds based on their peak area and network degree value included narcissoside, isorhamnetin-3-O-glucoside, and syringetin-3-O-glucoside, among others. Docking studies of the most relevant compounds revealed significant interactions with the top RIRI-related targets. In the in vivo RIRI experiments, pretreatment of ARBE improved kidney function and structural changes. ARBE reduced the renal expression of p-NfkB and cleaved caspase-3 by downregulating HSP90 and P53 in rats exposed to RIRI. Conclusion: Taken together, this study revealed the chemical composition of ARBE, depicted the interrelationship of the bioactive ingredients of ARBE with the RIRI-related molecular targets, and validated a nephroprotective effect of ARBE in RIRI.

Identification and analysis of necroptosis-associated signatures for prognostic and immune microenvironment evaluation in hepatocellular carcinoma

Background

Hepatocellular carcinoma remains the third most common cause of cancer-related deaths worldwide. Although great achievements have been made in resection, chemical therapies and immunotherapies, the pathogenesis and mechanism of HCC initiation and progression still need further exploration. Necroptosis genes have been reported to play an important role in HCC malignant activities, thus it is of great importance to comprehensively explore necroptosis-associated genes in HCC.

Methods

We chose the LIHC cohort from the TCGA, ICGC and GEO databases for this study. ConsensusClusterPlus was adopted to identify the necroptosis genes-based clusters, and LASSO cox regression was applied to construct the prognostic model based on necroptosis signatures. The GSEA and CIBERSORT algorithms were applied to evaluate the immune cell infiltration level. QPCR was also applied in this study to evaluate the expression level of genes in HCC.

Results

We identified three clusters, C1, C2 and C3. Compared with C2 and C3, the C1 cluster had the shortest overall survival time and highest immune score. The C1 was samples were significantly enriched in cell cycle pathways, some tumor epithelial-mesenchymal transition related signaling pathways, among others. The DEGs between the 3 clusters showed that C1 was enriched in cell cycle, DNA replication, cellular senescence, and p53 signaling pathways. The LASSO cox regression identified KPNA2, SLC1A5 and RAMP3 as prognostic model hub genes. The high risk-score subgroup had an elevated expression level of immune checkpoint genes and a higher TIDE score, which suggested that the high risk-score subgroup had a lower efficiency of immunotherapies. We also validated that the necroptosis signatures-based risk-score model had powerful prognosis prediction ability.

Conclusion

Based on necroptosis-related genes, we classified patients into 3 clusters, among which C1 had significantly shorter overall survival times. The proposed necroptosis signatures-based prognosis prediction model provides a novel approach in HCC survival prediction and clinical evaluation.