Propofol prevents oxidative stress and apoptosis by regulating iron homeostasis and targeting JAK/STAT3 signaling in SH-SY5Y cells

Exploiting the metabolic vulnerability of circulating tumour cells

Metastasis has a major part in the severity of disease and lethality of cancer. Circulating tumour cells (CTCs) represent a reservoir of metastatic precursors in circulation, most of which cannot survive due to hostile conditions in the bloodstream. Surviving cells colonise a secondary site based on a combination of physical, metabolic, and oxidative stress protection states required for that environment. Recent advances in CTC isolation methods and high-resolution 'omics technologies are revealing specific metabolic pathways that support this selection of CTCs. In this review, we discuss recent advances in our understanding of CTC biology and discoveries of adaptations in metabolic pathways during their selection. Understanding these traits and delineating mechanisms by which they confer acquired resistance or vulnerability in CTCs is crucial for developing successful prognostic and therapeutic strategies in cancer.

Transmembrane serine protease 6, a novel target for inhibition of neuronal tumor growth

Transmembrane serine protease 6 (Tmprss6) has been correlated with the occurrence and progression of tumors, but any specific molecular mechanism linking the enzyme to oncogenesis has remained elusive thus far. In the present study, we found that Tmprss6 markedly inhibited mouse neuroblastoma N2a (neuro-2a) cell proliferation and tumor growth in nude mice. Tmprss6 inhibits Smad1/5/8 phosphorylation by cleaving the bone morphogenetic protein (BMP) co-receptor, hemojuvelin (HJV). Ordinarily, phosphorylated Smad1/5/8 binds to Smad4 for nuclear translocation, which stimulates the expression of hepcidin, ultimately decreasing the export of iron through ferroportin 1 (FPN1). The decrease in cellular iron levels in neuro-2a cells with elevated Tmprss6 expression limited the availability of the metal forribo nucleotide reductase activity, thereby arresting the cell cycle prior to S phase. Interestingly, Smad4 promoted nuclear translocation of activating transcription factor 3 (ATF3) to activate the p38 mitogen-activated protein kinases signaling pathway by binding to ATF3, inducing apoptosis of neuro-2a cells and inhibiting tumor growth. Disruption of ATF3 expression significantly decreased apoptosis in Tmprss6 overexpressed neuro-2a cells. Our study describes a mechanism whereby Tmprss6 regulates the cell cycle and apoptosis. Thus, we propose Tmprss6 as a candidate target for inhibiting neuronal tumor growth.

Ferroptosis: an important player in the inflammatory response in diabetic nephropathy

Diabetic nephropathy (DN) is a chronic inflammatory disease that affects millions of diabetic patients worldwide. The key to treating of DN is early diagnosis and prevention. Once the patient enters the clinical proteinuria stage, renal damage is difficult to reverse. Therefore, developing early treatment methods is critical. DN pathogenesis results from various factors, among which the immune response and inflammation play major roles. Ferroptosis is a newly discovered type of programmed cell death characterized by iron-dependent lipid peroxidation and excessive ROS production. Recent studies have demonstrated that inflammation activation is closely related to the occurrence and development of ferroptosis. Moreover, hyperglycemia induces iron overload, lipid peroxidation, oxidative stress, inflammation, and renal fibrosis, all of which are related to DN pathogenesis, indicating that ferroptosis plays a key role in the development of DN. Therefore, this review focuses on the regulatory mechanisms of ferroptosis, and the mutual regulatory processes involved in the occurrence and development of DN and inflammation. By discussing and analyzing the relationship between ferroptosis and inflammation in the occurrence and development of DN, we can deepen our understanding of DN pathogenesis and develop new therapeutics targeting ferroptosis or inflammation-related regulatory mechanisms for patients with DN.

TBBPA and lead co-exposure induces grass carp liver cells apoptosis via ROS/JAK2/STAT3 signaling axis

Tetrabromobisphenol A (TBBPA) and lead (Pb) are widely used in industrial field, which poses a serious threat to human and animal health. In particular, a large volume of wastewater containing TBBPA and Pb was discharged into the aquatic environment, causing a seriously negative impact on fish. Currently, whether TBBPA and Pb have a synergistic toxicity on fish remains unclear. In this study, we used the grass carp hepatocytes (L8824 cell line) exposed to either TBBPA or Pb, or both to determine their potential impacts on fish. The results showed that Pb or TBBPA induced oxidative stress and the loss of mitochondrial membrane potential in grass carp hepatocytes. In contrast to the control cells, the levels of JAK2, p-JAK2, STAT3 and p-STAT3 were significantly upregulated after exposure to TBBPA and Pb. Furthermore, the levels of Caspase3, Caspase9 and Bax were all increased while the level of Bcl2 was decreased in hepatocytes exposed to TBBPA or Pb. Results of flow cytometry and AO/EB staining reveled significant increases in the number of apoptotic cells in the TBBPA and Pb group compared to the controls. Notably, cells exposed to both TBBPA and Pb exhibited more severe damage than the single exposure, manifested by a higher number of apoptotic cells in the co-exposure group than the single exposure groups. Nevertheless, N-acetyl-l-cysteine (NAC) treatment could remarkably alleviate oxidative damage and loss of membrane potential in grass carp hepatocytes induced by TBBPA and Pb. Altogether, our study showed that combined exposure of TBBPA and Pb has a synergistic toxicity due to, inducing oxidative stress to activate JAK2/STAT3 signaling pathway, resulting in apoptosis of carp hepatocytes. This study shed a new light on the toxicological mechanism of exposure of TBBPA and Pb and provided a potential treatment of toxicity induced by TBBPA and Pb.

Role of ferroptosis in effects of anesthetics on multiple organ diseases: A literature review

Anesthesiologists are often faced with patients combined with a series of organ injuries, such as acute lung injury, myocardial ischemia-reperfusion injury, and neurodegenerative diseases. With the in-depth study of these diseases, we are more aware of the choice and rational use of anesthetics for the prognosis of these patients. Ferroptosis is a new type of programmed cell death. This unique pattern of cell death, driven by an imbalance between oxides and antioxidants, is regulated by multiple cellular metabolic events, including redox homeostasis, iron handling, mitochondrial activity, and lipids peroxidation. Numerous studies confirmed that anesthetics modulate ferroptosis by interfering its machineries such as cystine-import-glutathione-glutathione peroxidase 4 axis, Heme oxygenase 1, nuclear factor erythroid 2-related factor 2, and iron homeostasis system. In this literature review, we systemically illustrated possible involvement of ferroptosis in effects of anesthetics and adjuvant drugs on multiple organ diseases, hoping our work may serve as a basis for further studies on regulating ferroptosis through anesthetics related pharmacological modulation and promoting the rational use of anesthetics.

Sevoflurane inhibited reproductive function in male mice by reducing oxidative phosphorylation through inducing iron deficiency

Sevoflurane (Sev) is one of the commonly used inhalation anesthetic chemicals in clinics. It has great impact on spermatogenesis and fertilization in male animals. The underlying mechanism remains largely unexplored. Based on our previous research, we hypothesized that Sev induced iron metabolism disturbance in the testis and epididymis and inhibited the spermatogenesis. In this study, two-month-old C57BL/6 male mice were treated with 3% Sev for 6 h, and their fertility (including sperm concentration, sperm mobility, and the number of offspring) was evaluated. Mice testis, epididymis, and sperm were harvested and subjected to Western blot analysis and immunofluorescence analysis. Iron levels were reflected by the gene expression of iron metabolism-related proteins (including ferritin, TfR1, and FpN1) and ICP-MS and Perl's iron staining. Electron transport and oxidative phosphorylation levels were measured by Oxygraph-2k and ATP contents. The activity of ribonucleotide reductase was evaluated by assay kit. DNA synthesis status in testis and/or epididymis was marked with BrdU. Cell proliferation was evaluated by double immunofluorescence staining of specific protein marker expression. Our results revealed that the mice exposed to Sev showed damaged testicular and epididymis structure and significantly reduced the sperm concentration, sperm motility, and fertility. Sev decreases the iron levels through down-regulating the expression of H-ferritin, L-ferritin, and FpN1, and up-regulating the expression of TfR1 in the testis and epididymis. Iron levels also significantly reduced in germ cells which decrease the number of germ cells, including sperm, Sertoli cells, and primary spermatocyte. Iron deficiency not only decreases electron transport, oxidative phosphorylation level, and ATP production but also suppresses the activity of ribonucleotide reductase and the expression of Ki67, DDX4, GATA1, and SCP3, indicating that Sev affects the spermatogenesis and development. Meanwhile, Sev impaired the blood-testis barrier by decreasing the ZO1 expression in the testis and epididymis. The damage effect induced by Sev can be significantly ameliorated by iron supplementation. In conclusion, our study illustrates a new mechanism by which Sev inhibits spermatogenesis and fertility through an oxidative phosphorylation pathway due to iron deficiency of epididymis and testis or sperm. Furthermore, the damaging effects could be ameliorated by iron supplementation.

The interaction between ferroptosis and inflammatory signaling pathways

Ferroptosis is an iron-dependent regulated cell death driven by excessive lipid peroxidation. Inflammation is one common and effective physiological event that protects against various stimuli to maintain tissue homeostasis. However, the dysregulation of inflammatory responses can cause imbalance of the immune system, cell dysfunction and death. Recent studies have pointed out that activation of inflammation, including the activation of multiple inflammation-related signaling pathways, can lead to ferroptosis. Among the related signal transduction pathways, we focused on five classical inflammatory pathways, namely, the JAK-STAT, NF-κB, inflammasome, cGAS-STING and MAPK signaling pathways, and expounded on their roles in ferroptosis. To date, many agents have shown therapeutic effects on ferroptosis-related diseases by modulating the aforementioned pathways in vivo and in vitro. Moreover, the regulatory effects of these pathways on iron metabolism and lipid peroxidation have been described in detail, contributing to further understanding of the pathophysiological process of ferroptosis. Taken together, targeting these pathways related to inflammation will provide appropriate ways to intervene ferroptosis and diseases.

A mini-review of the effects of inhalational and intravenous anesthetics on oxidative stress in dogs

General anesthesia increases the production of reactive oxygen species (ROS), which can exacerbate or increase oxidative stress and thus affect the prognosis of surgical procedures. Oxidative stress has been implicated in the development of cardiovascular, dermatologic, oncologic, and other diseases in dogs, as well as ischemia and reperfusion injury. Some anesthetics, such as halogenated anesthetics, have been shown to stimulate the production of ROS, while others, such as propofol, have antioxidant properties. However, the antioxidant effects of these anesthetics may not be sufficient to counteract oxidative damage at the doses used clinically. Nevertheless, the effects of anesthetics should be considered to minimize oxidative damage during anesthesia in dogs to improve the outcome of procedures requiring general anesthesia. This mini-review addresses the current knowledge on oxidative stress during inhalational and intravenous anesthesia in dogs. There is still a lack of information on the management of anesthesia in dogs with respect to oxidative stress. Further research, including comprehensive clinical studies is needed to better understand oxidative injury mechanisms and improve perioperative protocols during anesthesia in dogs.

Neochamaejasmin B extracted from Stellera chamaejasme L. induces apoptosis through caspase-10-dependent way in insect neuronal cells

To explore the toxicity mechanisms of neochamaejasmin B (NCB) extracted from Stellera chamaejasme L., we first evaluated its cytotoxicity in neuronal cells of Helicoverpa zea (AW1 cells). NCB inhibited cell growth and was cytotoxic to AW1 cells in a dose-dependent manner. Further, transmission electron microscopy (TEM) was used to analyze the microstructure, and typical apoptotic characteristics were observed in AW1 cells treated with NCB. Moreover, the NCB-induced apoptosis was dose dependent. Subsequently, we explored the mechanism of apoptosis. A decline in the mitochondrial membrane potential (MMP) was found. Also, the levels of Bax were increased with increases in drug concentration, but there was no statistical difference in Bcl-2 levels at different NCB doses. Caspase-3 and caspase-10 activity was increased. These findings confirmed that NCB induced apoptosis in AW1 cells through a caspase-10-dependent mechanism. The results provide the basic information needed for understanding the toxicity and mechanisms of action of NCB, which could potentially be used to develop NCB as a new insecticide.

Pancreatic Cancer and Microenvironments: Implications of Anesthesia

Simple Summary

Pancreatic cancer is a lethal malignant neoplasm with less than 10% 5-year relative survival after the initial diagnosis. Several factors may be related to the poor prognosis of pancreatic cancer, including the rapid tumor progression, increased metastatic propensity, insignificant symptoms, shortage of early diagnostic biomarkers, and its tendency toward resistance to both chemotherapy and radiotherapy. Pancreatic neoplastic cells interact intimately with a complicated microenvironment that can foster drug resistance, metastasis, or relapse in pancreatic cancer. In addition, evidence shows that perioperative factors, including surgical manipulation, anesthetics, or analgesics, might alter the tumor microenvironment and cancer progression. This review outlines the up-to-date knowledge of anesthesia implications in the pancreatic microenvironment and provides future anesthetic strategies for improving pancreatic cancer survival.

Abstract

Pancreatic malignancy is a lethal neoplasm, as well as one of the leading causes of cancer-associated mortality, having a 5-year overall survival rate of less than 10%. The average life expectancy of patients with advanced pancreatic cancer does not exceed six months. Although surgical excision is a favorable modality for long-term survival of pancreatic neoplasm, metastasis is initially identified in nearly 80% of the patients by the time of diagnosis, making the development of therapeutic policy for pancreatic cancer extremely daunting. Emerging evidence shows that pancreatic neoplastic cells interact intimately with a complicated microenvironment that can foster drug resistance, metastasis, or relapse in pancreatic cancer. As a result, the necessity of gaining further insight should be focused on the pancreatic microenvironment contributing to cancer progression. Numerous evidence reveals that perioperative factors, including surgical manipulation and anesthetics (e.g., propofol, volatile anesthetics, local anesthetics, epidural anesthesia/analgesia, midazolam), analgesics (e.g., opioids, non-steroidal anti-inflammatory drugs, tramadol), and anesthetic adjuvants (such as ketamine and dexmedetomidine), might alter the tumor microenvironment and cancer progression by affecting perioperative inflammatory or immune responses during cancer surgery. Therefore, the anesthesiologist plays an important role in perioperative management and may affect surgical outcomes. However, the literature on the impact of anesthesia on the pancreatic cancer microenvironment and progression is limited. This review summarizes the current knowledge of the implications of anesthesia in the pancreatic microenvironment and provides future anesthetic strategies for improving pancreatic cancer survival rates.

The effect of propofol on hypoxia- and TNF-α-mediated BDNF/TrkB pathway dysregulation in primary rat hippocampal neurons

AIMS

Hypoxia and inflammation may lead to BDNF/TrkB dysregulation and neurological disorders. Propofol is an anesthetic with neuroprotective properties. We wondered whether and how propofol affected BDNF/TrkB pathway in hippocampal neurons and astrocytes.

METHODS

Primary rat hippocampal neurons and astrocytes were cultured and exposed to propofol followed by hypoxia or TNF-α treatment. The expression of BDNF and the expression/truncation/phosphorylation of TrkB were measured. The underlying mechanisms were investigated.

RESULTS

Hypoxia and TNF-α reduced the expression of BDNF, which was reversed by pretreatment of 25 μM propofol in hippocampal neurons. Furthermore, hypoxia and TNF-α increased the phosphorylation of ERK and phosphorylation of CREB at Ser142, while reduced the phosphorylation of CREB at Ser133, which were all reversed by 25 μM propofol and 10 μM ERK inhibitor. In addition, hypoxia or TNF-α did not affect TrkB expression, truncation, or phosphorylation in hippocampal neurons and astrocytes. However, in hippocampal neurons, 50 μM propofol induced TrkB phosphorylation, which may be mediated by p35 expression and Cdk5 activation, as suggested by the data showing that blockade of p35 or Cdk5 expression mitigated propofol-induced TrkB phosphorylation.

CONCLUSIONS

Propofol modulated BDNF/TrkB pathway in hippocampal neurons via ERK/CREB and p35/Cdk5 under the condition of hypoxia or TNF-α exposure.

Propofol via Antioxidant Property Attenuated Hypoxia-Mediated Mitochondrial Dynamic Imbalance and Malfunction in Primary Rat Hippocampal Neurons

BACKGROUND

Hypoxia may induce mitochondrial abnormality, which is associated with a variety of clinical phenotypes in the central nervous system. Propofol is an anesthetic agent with neuroprotective property. We examined whether and how propofol protected hypoxia-induced mitochondrial abnormality in neurons.

METHODS

Primary rat hippocampal neurons were exposed to propofol followed by hypoxia treatment. Neuron viability, mitochondrial morphology, mitochondrial permeability transition pore (mPTP) opening, mitochondrial membrane potential (MMP), and adenosine triphosphate (ATP) production were measured. Mechanisms including reactive oxygen species (ROS), extracellular regulated protein kinase (ERK), protein kinase A (PKA), HIF-1α, Drp1, Fis1, Mfn1, Mfn2, and Opa1 were investigated.

RESULTS

Hypoxia increased intracellular ROS production and induced mPTP opening, while reducing ATP production, MMP values, and neuron viability. Hypoxia impaired mitochondrial dynamic balance by increasing mitochondrial fragmentation. Further, hypoxia induced the translocation of HIF-1α and increased the expression of Drp1, while having no effect on Fis1 expression. In addition, hypoxia induced the phosphorylation of ERK and Drp1ser616, while reducing the phosphorylation of PKA and Drp1ser637. Importantly, we demonstrated all these effects were attenuated by pretreatment of neurons with 50 μM propofol, antioxidant α-tocopherol, and ROS scavenger ebselen. Besides, hypoxia, propofol, α-tocopherol, or ebselen had no effect on the expression of Mfn1, Mfn2, and Opa1.

CONCLUSIONS

In rat hippocampal neurons, hypoxia induced oxidative stress, caused mitochondrial dynamic imbalance and malfunction, and reduced neuron viability. Propofol protected mitochondrial abnormality and neuron viability via antioxidant property, and the molecular mechanisms involved HIF-1α-mediated Drp1 expression and ERK/PKA-mediated Drp1 phosphorylation.

An atlas of dynamic peripheral blood mononuclear cell landscapes in human perioperative anaesthesia/surgery

BACKGROUND

The number of patients receiving anaesthesia is increasing, but the impact of general anaesthesia on the patient's immune system remains unclear. The aim of the present study is to investigate dynamics of systemic immune cell responses to anaesthesia during perioperative period at a single-cell solution.

METHODS

The peripheral blood mononuclear cells (PBMCs) and clinical phenomes were harvested and recorded 1 day before anaesthesia and operation, just after anaesthesia (0 h), and 24 and 48 h after anaesthesia. Single-cell sequencing of PBMCs was performed with 10× genomics. Subsequently, data analysis was performed with R packages: Seurat, clusterProfiler and CellPhoneDB.

RESULTS

We found that the cluster of CD56+ NK cells changed at 0 h and the cluster of monocytes increased at 24 and 48 h after anaesthesia. The characteristic genes of CD56+ NK cells were mainly enriched in the Jak-STAT signalling pathway and in cell adhesion molecules (24 h) and carbon metabolism (48 h). The communication between CD14+ monocytes and other cells decreased substantially 0 and 48 h after operation. The number of plasma cells enriched in protein export in men was substantially higher than that in women, although the total number in patients decreased 24 h after operation. CD14+ monocytes dominated that cell-cell communications appeared in females, while CD8+ NKT cells dominated that cell-cell communications appeared in male. The number of plasma cells increased substantially in patients with major surgical trauma, with enrichments of pentose phosphate pathway. The communications between plasma cells with other cells varied between surgical severities and anaesthetic forms. The intravenous anaesthesia caused major alterations of cell types, including CD14+ monocytes, plasmas cells and MAIT cells, as compared with inhalation anaesthesia.

CONCLUSION

We initially reported the roles of perioperative anaesthesia/surgery in temporal phenomes of circulating immune cells at a single-cell solution. Thus, the protection against immune cell changes would benefit the recovery from anaesthesia/surgery.

Anesthesia-Induced Oxidative Stress: Are There Differences between Intravenous and Inhaled Anesthetics?

Agents used for the induction of anesthesia have been shown to either promote or mitigate oxidative stress. A fine balance between the presence of reactive oxygen species (ROS) and antioxidants is crucial for the proper normal functioning of the cell. A basal concentration of ROS is essential for the manifestation of cellular functions, whereas disproportionate levels of ROS cause damage to cellular macromolecules such as DNA, lipids, and proteins, eventually leading to necrosis and apoptosis. Increased ROS has been linked with numerous illnesses, such as cardiovascular, immune system, liver, and kidney, and has been shown to promote cancer and accelerate aging. Knowledge of the various pharmacologic agents that increase or reduce oxidative stress may promote a safer way of inducing anesthesia. Furthermore, surgery itself leads to increased ROS production and ischemia/reperfusion injury. Indeed, increased perioperative oxidative stress has been correlated with increased postoperative complications and prolonged recovery. Anesthesiologists care for patients during the whole spectrum of perioperative care and thus are in a unique position to deliver countermeasures to oxidative stress. Using preferentially an induction agent which reduces oxidative stress might lead to better clinical outcomes and fewer postoperative complications. Propofol has been shown in several studies to reduce oxidative stress, which reduces postoperative complications and leads to a faster recovery, and thus might represent the preferred induction agent in the right clinical setting.

Propofol induces the ferroptosis of colorectal cancer cells by downregulating STAT3 expression

Propofol is a commonly used intravenous anesthetic agent that can also suppress the proliferation of various human cancer types, including colorectal cancer (CRC). The present study aimed to investigate whether propofol could induce the ferroptosis of CRC cells by regulating signal transducer and activator of transcription 3 (STAT3). STAT3 expression in normal and CRC tissues was measured. Human normal colonic epithelial NCM460 cells and human CRC SW480 cells were exposed to different concentrations of propofol and then cell viability was detected. SW480 cells were transfected with a vector overexpressing STAT3 and treated with propofol, and the cell viability, colony formation, cell proliferation, iron level, ROS production and ferroptosis of these cells and control cells were evaluated. Overall, the results showed that STAT3 was highly expressed in CRC tissues. Propofol exerted no marked effect on NCM460 cell viability, but inhibited SW480 cell viability in a concentration-dependent manner. Meanwhile, STAT3 was downregulated by propofol in a concentration-dependent manner. Propofol also inhibited CRC cell proliferation and colony formation, and enhanced cellular iron and ROS levels. Additionally, the expression of proteins involved in ferroptosis was also altered by propofol, including the upregulation of CHAC1 and PTGS2 expression in CRC cells, and the inhibition of GPX4 expression. However, STAT3 overexpression blocked the effect of propofol on CRC cells. In conclusion, propofol may trigger the ferroptosis of CRC cells by downregulating STAT3 expression.

Nuciferine protects against folic acid-induced acute kidney injury by inhibiting ferroptosis

BACKGROUND AND PURPOSE

Acute kidney injury is a common clinical problem with no definitive or specific treatment. Therefore, the molecular mechanisms of acute kidney injury must be fully understood to develop novel treatments. Nuciferine, a major bioactive compound isolated from the lotus leaf, possesses extensive pharmacological activities. Its effect on folic acid-induced acute kidney injury, however, remains unknown. Here, we aimed to clarify the pharmacological effects of nuciferine and its mechanisms of action in acute kidney injury.

EXPERIMENTAL APPROACH

The effects of nuciferine on folic acid-induced acute kidney injury in mice were investigated. HK-2 human proximal tubular epithelial cells and HEK293T HEK cells were used to evaluate the protective effect of nuciferine on RSL3-induced ferroptosis.

KEY RESULTS

Nuciferine treatment mitigated the pathological alterations, ameliorated inflammatory cell infiltration and improved kidney dysfunction in mice with folic acid-induced acute kidney injury. In HK-2 and HEK293T cells, nuciferine significantly prevented RSL3-induced ferroptotic cell death. Mechanistically, nuciferine significantly inhibited ferroptosis by preventing iron accumulation and lipid peroxidation in vitro and in vivo. Moreover, knockdown of glutathione (GSH) peroxidase 4 (GPX4) abolished the protective effect of nuciferine against ferroptosis.

CONCLUSION AND IMPLICATIONS

Nuciferine ameliorated renal injury in mice with acute kidney injury, perhaps by inhibiting the ferroptosis. Nuciferine may represent a novel treatment that improves recovery from acute kidney injury by targeting ferroptosis.

Succinate accumulation contributes to oxidative stress and iron accumulation in pentylenetetrazol-induced epileptogenesis and kainic acid-induced seizure

This study explored the role of succinate accumulation in the oxidative stress and iron accumulation in both pentylenetetrazol (PTZ)-induced epileptogenesis and kainic acid (KA)-induced status epilepticus (SE). The levels of succinate, oxidative stress, iron content, iron-related protein expression, and the severity of neuronal injury and seizures were measured in both models. We found that increased concentrations of succinate were associated with increased levels of oxidative stress, iron content, iron regulator protein, and iron importer divalent metal transporter 1, as well as decreased levels of iron exporter ferropotin 1. Aggravated neuronal injury was observed in the hippocampi and cortices of both models. The cell-permeable molecule dimethyl malonate (DM), a competitive inhibitor of succinate dehydrogenase (SDH), significantly attenuated succinate accumulation, reduced the oxidative stress and iron levels, and mitigated the severity of the seizures and neuronal injury. Our results thus indicate that the accumulation of succinate due to the reverse catalysis of SDH may exacerbate oxidative stress and thus induce iron accumulation and neuronal injury in both models. Targeting succinate accumulation may achieve neuroprotective and anti-seizure effects.

Externally added cystatin C reduces growth of A375 melanoma cells by increasing cell cycle time

Some secreted cysteine protease inhibitors of the cystatin family appear to affect intracellular proteolysis and growth of human cells, as a result of internalization. Here, we studied the effects of external addition of the most abundant human cystatin, cystatin C, on viability and proliferation of cancer cells in culture. A dose‐dependent decrease in viable cells was seen for A375 melanoma, MCF‐7 breast cancer, and PC‐3 prostate cancer cells cultured in 1–5 µm cystatin C after 24 h. Real‐time assessment of growth rates in A375 cell cultures for 48 h by digital holographic microscopy showed an increased doubling time for cells cultured in the presence of 5 µm cystatin C (20.1 h) compared with control cells (14.7 h). A prolonged doubling time was already observed during the first 12 h, indicating a rapid general decrease in cell proliferation at the population level. Tracking of individual cells in phase holographic images showed that dividing cells incubated with 5 µm cystatin C underwent fewer mitoses during 48 h than control cells. In addition, the time between cell divisions was longer, especially for the first cell cycle. Incubation with the variant W106F‐cystatin C (with high cellular uptake rate) resulted in a lower number of viable cells and a prolonged doubling time than when cells were incubated with wild‐type cystatin C, but no effect was observed for (R24A,R25A)‐cystatin C (low cellular uptake). Thus, cystatin C causes prolonged cell division leading to decreased proliferation of melanoma cells, and internalization seems to be a prerequisite for this effect.

Ferroptosis was more initial in cell death caused by iron overload and its underlying mechanism in Parkinson's disease

Ferroptosis, an iron-dependent nonapoptotic cell death, was referred in neurodegenerative diseases, but its role in Parkinson's disease remains unclear. Here, we used ferric ammonium citrate (FAC) to treat dopaminergic cell to mimic the iron overload during the progression of Parkinson's disease (PD). We found that the cell death types of iron-overloaded dopaminergic cells induced by concentrations of FAC were different. Ferroptosis firstly occurred in a relatively low concentration of FAC-treated group, and then apoptosis appeared in response to the increased iron doses. Moreover, both ferroptosis and apoptosis caused by iron overload could be rescued by inhibitors of ferroptosis, but inhibitors of apoptosis did not prevent the occurrence of ferroptosis. We verified that ferroptosis occurred before apoptosis in α-SynA53T homozygous PD mice model. The underlying mechanism might be associated with the p53 signaling pathway, but not MAPK signaling pathway. Collectively, our results revealed a previously unappreciated role of ferroptosis in the early stages of PD and indicated that ferroptosis could elicit apoptosis in cell death caused by iron overload.

Puerarin protects against iron overload-induced retinal injury through regulation of iron-handling proteins

Excess iron content can build up in the retina and lead to iron-mediated retinal injury. An important isoflavone C-glucoside, puerarin, has been reported to be involved in retinal protection. In this experiment, we studied the effects and potential mechanisms of puerarin on retinal injury in vivo and in vitro. We found that puerarin reduced serum and retinal iron content, attenuated the pathophysiological changes and retinal iron deposition, and partially prevented the decrease of rhodopsin and retinal pigment epithelium-specific 65 kDa protein expression in retinas of iron-overload mice. Puerarin rescued the abnormal expression of iron-handling proteins in the mouse retina and suppressed the oxidative stress induced by iron overload, as evident from the enhanced activity of superoxide dismutase, catalase, and glutathione peroxidase and decreased content of malondialdehyde. Moreover, puerarin inhibited the phosphorylation of p38 and ERK mitogen-activated protein kinases (MAPKs) and signal transducer and activator of transcription 3 (STAT3), thereby protecting the retinal cells from apoptosis by suppressing cytochrome c release, caspase activation, and poly (ADP-ribose) polymerase cleavage in vivo. Also, the ability of puerarin to regulate iron-handling proteins, decrease intracellular Fe²⁺, and inhibit cell apoptosis was further confirmed in ARPE-19 cells. The experimental data verify the protective role of puerarin in the treatment of retinal injury caused by iron overload; its possible mechanisms might be associated with regulation of iron-handling proteins, enhancement of the antioxidant capacity, and the inhibition of MAPK and STAT3 activation and the apoptotic pathways under iron overload conditions.