HSP90 inhibitor 17AAG attenuates sevoflurane-induced neurotoxicity in rats and human neuroglioma cells via induction of HSP70

Comprehensive review of perioperative factors influencing ferroptosis

The perioperative period encompasses all phases of patient care from the decision to perform surgery until full recovery. Ferroptosis, a newly identified type of regulated cell death, influences a wide array of diseases, including those affecting the prognosis and regression of surgical patients, such as ischemia-reperfusion injury and perioperative cognitive dysfunction. This review systematically examines perioperative factors impacting ferroptosis such as surgical trauma-induced stress, tissue hypoxia, anesthetics, hypothermia, and blood transfusion. By analyzing their intrinsic relationships, we aim to improve intraoperative management, enhance perioperative safety, prevent complications, and support high-quality postoperative recovery, ultimately improving patient outcomes.

HSP90 Inhibition Attenuated Isoflurane-Induced Neurotoxicity in Mice and Human Neuroglioma Cells

Isoflurane, a widely used inhalation anesthetic in clinical practice, is associated with an increased risk of neuronal injury. Heat shock protein 90 (HSP90) plays a crucial role in maintaining neuronal homeostasis under stress conditions; however, its role during isoflurane exposure remains poorly understood. In this study, we aimed to investigate the protective effects of HSP90 inhibition and explore the regulatory mechanisms underlying these effects during isoflurane exposure. We found that the HSP90 inhibitor 17-N-allylamino-17-demethoxygeldanamycin (17 AAG) has great protective effects in mitigating isoflurane-induced ferroptosis of mouse hippocampus and cultured neuronal cells. We focused on the activity of the crucial protein GPX4 in ferroptosis and found that 17 AAG exerted protective effects, preserving the physiological GPX4 activity under isoflurane exposure; further, 17 AAG restored the protein level of GPX4. Further, we observed that the chaperone-mediated autophagy (CMA) pathway was activated; 17 AAG also mediated GPX4 degradation under isoflurane exposure. Additionally, it interfered with the formation of complexes between HSP90 and Lamp-2a, inhibiting CMA activity, followed by the blockade of GPX4 degradation, further affecting the isoflurane-induced ferroptosis. Based on these findings, we proposed HSP90 inhibition as a protective mechanism against isoflurane-induced ferroptosis in neurons.

The Myc Family and the Metastasis Suppressor NDRG1: Targeting Key Molecular Interactions with Innovative Therapeutics

Cancer is a leading cause of death worldwide, resulting in ∼10 million deaths in 2020. Major oncogenic effectors are the Myc proto-oncogene family, which consists of three members including c-Myc, N-Myc, and L-Myc. As a pertinent example of the role of the Myc family in tumorigenesis, amplification of MYCN in childhood neuroblastoma strongly correlates with poor patient prognosis. Complexes between Myc oncoproteins and their partners such as hypoxia-inducible factor-1α and Myc-associated protein X (MAX) result in proliferation arrest and pro-proliferative effects, respectively. Interactions with other proteins are also important for N-Myc activity. For instance, the enhancer of zest homolog 2 (EZH2) binds directly to N-Myc to stabilize it by acting as a competitor against the ubiquitin ligase, SCFFBXW7, which prevents proteasomal degradation. Heat shock protein 90 may also be involved in N-Myc stabilization since it binds to EZH2 and prevents its degradation. N-Myc downstream-regulated gene 1 (NDRG1) is downregulated by N-Myc and participates in the regulation of cellular proliferation via associating with other proteins, such as glycogen synthase kinase-3β and low-density lipoprotein receptor-related protein 6. These molecular interactions provide a better understanding of the biologic roles of N-Myc and NDRG1, which can be potentially used as therapeutic targets. In addition to directly targeting these proteins, disrupting their key interactions may also be a promising strategy for anti-cancer drug development. This review examines the interactions between the Myc proteins and other molecules, with a special focus on the relationship between N-Myc and NDRG1 and possible therapeutic interventions. SIGNIFICANCE STATEMENT: Neuroblastoma is one of the most common childhood solid tumors, with a dismal five-year survival rate. This problem makes it imperative to discover new and more effective therapeutics. The molecular interactions between major oncogenic drivers of the Myc family and other key proteins; for example, the metastasis suppressor, NDRG1, may potentially be used as targets for anti-neuroblastoma drug development. In addition to directly targeting these proteins, disrupting their key molecular interactions may also be promising for drug discovery.

Exogenous recombinant Hsp70 attenuates sevoflurane anesthesia-induced cognitive dysfunction in aged mice

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a severe postoperative neurological sequela in elderly patients, and there is currently no standard treatment for POCD. In this study, whether recombinant human heat shock protein 70 (rHsp70) could alleviate sevoflurane-induced cognitive impairment in aged mice is investigated.

METHODS

To determine the prophylactic effect of rHsp70 in sevoflurane-induced cognitive dysfunction, aged mice were pretreated with different concentrations of rHsp70 (29.4, 58.8, and 117.6 μg/kg; intranasal injected; N = 12) every day for 1 week; then, 3% sevoflurane was utilized to anesthetize the aged mice. Cognitive function, neurotoxicity, and serum and hippocampal Hsp70 levels in aged mice undergoing sevoflurane anesthesia were assessed by the Morris water maze test and enzyme-linked immunosorbent assay. The effects of rHsp70 on inflammatory response were assessed by proinflammatory cytokine production and nuclear factor-κB (NF-κB) activation assays.

RESULTS

We found that aged mice exposed to sevoflurane showed reduced learning and memory ability and reduced Hsp70 expression, which were both restored by rHsp70 pretreatment. RHsp70 also reversed sevoflurane-induced up-regulated Bax and Bcl-2 expression and interleukin-1, IL-6, and monocyte chemoattractant protein-1 overproduction. Finally, rHsp70 pretreatment suppressed sevoflurane-induced NF-κB activation. Our study indicated that rHsp70 was sufficient to suppress sevoflurane-induced cognitive decline and neurotoxicity.

CONCLUSION

Our important finding warrants further study on the clinical application of rHsp70 in elderly patients undergoing anesthesia.

Probing the biological toxicity of pyrene to the earthworm Eisenia fetida and the toxicity pathways of oxidative damage: A systematic study at the animal and molecular levels

Pyrene (Pyr), a widely used tetracyclic aromatic hydrocarbon, enters soil in large quantities and causes environmental pollution due to its production and mining. In order to systematically study the biotoxicity of pyrene to model organisms Eisenia fetida in soil, experiments were carried out from four dimensions: animal, tissue, cell and molecule. Experimental results proved that the mortality rate increased with increasing concentration and time of exposure to pyrene, while the mean body weight and spawning rate decreased. Meanwhile, when the pyrene concentration reached 900 mg/kg, the seminal vesicle and longitudinal muscle of the earthworm showed obvious atrophy. Experimental results at the cellular level showed that pyrene induced cell membrane damage and Ca²⁺ influx triggered mitochondrial membrane depolarization and a surge in ROS levels. Oxidative stress causes damage to proteins and lipids and DNA inside cells. When the mortality rate was 91.67 %, the Olive Tail Movement (OTM) of the comet experiment reached 15. The results of molecular level tests showed that pyrene inhibited the activity of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) mainly by changing the microenvironment and secondary structure of amino acid Tyr 108. The weakened function of direct antioxidant enzymes may be the root cause of the excessive increase of reactive oxygen species (ROS) in cells. The systematic approach used in this study enriches the network of toxic pathways in toxicological studies, and basic data on the biological toxicity of pyrene can provide support for future soil contamination detection.

Inhibitive Effect of Luteolin on Sevoflurane-Induced Neurotoxicity through Activation of the Autophagy Pathway by HMOX1

Luteolin is a flavone compound occurring in a variety of medicinal plants, which is reported to have neuroprotective properties. In this study, we aimed to explore the effects of luteolin in alleviating sevoflurane-induced neurotoxicity. GeneCards and Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform were employed to screen luteolin, sevoflurane, and neurotoxicity-related genes. Subsequently, we isolated primary neurons from the hippocampus of 1-day-old C57BL/6J mice and tested for cytotoxicity after treatment of different concentrations of luteolin. Next, we measured the expression of apoptosis by flow cytometry and assessed inflammation-related factors, including heme oxygenase-1 expression detected by immunohistochemical staining and neuronal apoptosis. Finally, water maze, open field, and fear conditioning tests were conducted to observe the interaction between luteolin and sevoflurane in cognitive impairment of mice. Luteolin had the lowest cytotoxicity at concentrations of 30 or 60 μg/mL; we selected 30 μg/mL for drug administration experiments in vitro. Luteolin inhibited sevoflurane-induced neuronal apoptosis and inflammatory responses through the autophagic pathway and thus ameliorated sevoflurane-induced cognitive impairment in mice. Mechanistically, luteolin up-regulated heme oxygenase-1 expression, which activated the autophagy pathway in vitro. This was confirmed by subsequent histological experiments in mice and behavioral results showing rescue cognitive impairment. Our findings uncovered an inhibitory role of luteolin in sevoflurane-induced neuronal apoptosis and inflammatory response through activation of autophagy arising from up-regulation of heme oxygenase-1, thereby alleviating sevoflurane-induced cognitive impairment in mice.