ADAMTS-13-regulated nuclear factor E2-related factor 2 signaling inhibits ferroptosis to ameliorate cisplatin-induced acute kidney injuy.

ADAMTS-13 plays an important role in acute kidney injury (AKI), but the mechanism of cisplatin (CP) induced AKI remains unclear. Ferroptosis is increased in CP-induced AKI, and ADAMTS13 levels are associated with ferritin expression. In this article, we will explore the relationship between the three. After CP induction, mice were given 0.1 and 0.3 nmol/kg ADAMTS-13, and then serum creatinine (Scr) and blood urea nitrogen (BUN) were detected by the kits. The pathological changes of renal tissue were observed by staining with HE and PAS staining, and Western blot detected the expressions of KIM1 and NGAL in renal tissu. Perl's staining detected iron deposition in renal tissues, the kits detected iron levels, and western blot detected the expression of ferroptosis related proteins. Then the mechanism was further explored by adding ferroptosis inhibitors Ferrostatin 1 (Fer-1) and iron supplements Fe. The expression of Nrf2 pathway related proteins were detected by Western blot. We found that ADAMTS13 alleviated CP-induced ferroptosis in AKI mice with renal function impairment and tubular damage. Fer-1partially reversed CP-induced AKI, and Fe exacerbated this effect. ADAMTS13 alleviated CP-induced inflammatory response and oxidative stress in AKI mice, during which the Nrf2 signaling pathway was abnormal. Overall, ADAMTS-13-regulated Nrf2 signaling inhibits ferroptosis to ameliorate CP-induced AKI.

Therapeutic Potential for Regulation of the Nuclear Factor Kappa-B Transcription Factor p65 to Prevent Cellular Senescence and Activation of Pro-Inflammatory in Mesenchymal Stem Cells.

Mesenchymal stem cells have an important potential in the treatment of age-related diseases. In the last years, small extracellular vesicles derived from these stem cells have been proposed as cell-free therapies. Cellular senescence and proinflammatory activation are involved in the loss of therapeutic capacity and in the phenomenon called inflamm-aging. The regulators of these two biological processes in mesenchymal stem cells are not well-known. In this study, we found that p65 is activated during cellular senescence and inflammatory activation in human umbilical cord-derived mesenchymal stem cell. To demonstrate the central role of p65 in these two processes, we used small-molecular inhibitors of p65, such as JSH-23, MG-132 and curcumin. We found that the inhibition of p65 prevents the cellular senescence phenotype in human umbilical cord-derived mesenchymal stem cells. Besides, p65 inhibition produced the inactivation of proinflammatory molecules as components of a senescence-associated secretory phenotype (SASP) (interleukin-6 and interleukin-8 (IL-6 and IL-8)). Additionally, we found that the inhibition of p65 prevents the transmission of paracrine senescence between mesenchymal stem cells and the proinflammatory message through small extracellular vesicles. Our work highlights the important role of p65 and its inhibition to restore the loss of functionality of small extracellular vesicles from senescent mesenchymal stem cells and their inflamm-aging signature.

Hematopoietic protection and mechanisms of ferrostatin-1 on hematopoietic acute radiation syndrome of mice.

PURPOSE: Baicalein (an anti-ferroptosis drug) was recently reported to synergistically improve the survival rate of mice following a high dose of total body irradiation with anti-apoptosis and anti-necroptosis drugs. At the same time, our group has demonstrated that ferrostatin-1, a ferroptosis inhibitor, improves the survival rate of a mouse model of hematopoietic acute radiation syndrome to 60% for 150 days (p < .001). These phenomena suggest that ferroptosis inhibition can mitigate radiation damage. In this study, we continued to study the mechanisms by which ferrostatin-1 alleviated radiation-induced ferroptosis and subsequent hematopoietic acute radiation syndrome. MATERIALS AND METHODS: Male ICR mice (8-10 weeks old) were exposed to doses of 0, 8, or 10 Gy irradiated from a 137Cs source. Ferrostatin-1 was intraperitoneally injected into mice 72 h post-irradiation. Bone marrow mononuclear cells (BMMCs) and peripheral blood cells were counted. The changes in iron-related parameters, lipid metabolic enzymes, lipid peroxidation repair molecules (glutathione peroxidase 4, glutathione, and coenzyme Q10), and inflammatory factors (TNF-α, IL-6, and IL-1ß) were evaluated using biochemical or antibody techniques. RESULTS: Ferrostatin-1 increased the number of red and white blood cells, lymphocytes, and monocytes in the peripheral blood after total body irradiation in mice by mitigating the ferroptosis of BMMCs. Total body irradiation induced ferroptosis in BMMCs by increasing the iron and lipid peroxidation levels and depleting the acyl-CoA synthetase long-chain family member 4 (ASCL4), lipoxygenase 15, glutathione peroxidase 4, and glutathione levels. Ferroptotic BMMCs did not release TNF-α, IL-6, or IL-1ß at the early stage of radiation exposure. Ferrostatin-1 mitigated the lipid peroxidation of radiation-induced ferroptosis by attenuating increases in levels of hemosiderin and liable iron pool and decreases in levels of ASCL4 and glutathione peroxidase 4. CONCLUSIONS: The onset of total body irradiation-induced ferroptosis in BMMCs involved changes in iron, lipid metabolic enzymes, and anti-lipid peroxidation molecules. Ferrostatin-1 could be a potential radiation mitigation agent by acting on these targets.

Covalent Organic Framework-Based Nanocomposite for Synergetic Photo-, Chemodynamic-, and Immunotherapies.

Cancer deaths are mainly caused by tumor metastases. However, tumor ablation therapies can only target the primary tumor but not inhibit tumor metastasis. Herein, a multifunctional covalent organic framework (COF)-based nanocomposite is designed for synergetic photo-, chemodynamic- and immunotherapies. Specifically, the synthesized COF possesses the ability to produce singlet oxygen under the 650 nm laser irradiation. After being metallized with FeCl3, p-phenylenediamine is polymerized on the surface of COF with Fe3+ as the oxidant. The obtained poly(p-phenylenediamine) can be used for photothermal therapy. Meanwhile, the overexpressed H2O2 in the tumor would be further catalyzed and decomposed into hydroxyl radicals (•OH) by the Fe3+/Fe2+ redox couple via Fenton reaction. Intriguingly, the increase of temperature caused by photothermal therapy can accelerate the production of •OH. Moreover, the tumor-associated antigen induced a robust antitumor immune response and effectively inhibited tumor metastasis in the presence of anti-PD-L1 checkpoint blockade. Such a COF-based multifunctional nanoplatform provides an efficacious treatment strategy for both the primary tumor and tumor metastasis.

Ferroptosis driven by radical oxidation of n-6 polyunsaturated fatty acids mediates acetaminophen-induced acute liver failure.

Acetaminophen (APAP) overdose is a common cause of drug-induced acute liver failure. Although hepatocyte cell death is considered to be the critical event in APAP-induced hepatotoxicity, the underlying mechanism remains unclear. Ferroptosis is a newly discovered type of cell death that is caused by a loss of cellular redox homeostasis. As glutathione (GSH) depletion triggers APAP-induced hepatotoxicity, we investigated the role of ferroptosis in a murine model of APAP-induced acute liver failure. APAP-induced hepatotoxicity (evaluated in terms of ALT, AST, and the histopathological score), lipid peroxidation (4-HNE and MDA), and upregulation of the ferroptosis maker PTGS2 mRNA were markedly prevented by the ferroptosis-specific inhibitor ferrostatin-1 (Fer-1). Fer-1 treatment also completely prevented mortality induced by high-dose APAP. Similarly, APAP-induced hepatotoxicity and lipid peroxidation were prevented by the iron chelator deferoxamine. Using mass spectrometry, we found that lipid peroxides derived from n-6 fatty acids, mainly arachidonic acid, were elevated by APAP, and that auto-oxidation is the predominant mechanism of APAP-derived lipid oxidation. APAP-induced hepatotoxicity was also prevented by genetic inhibition of acyl-CoA synthetase long-chain family member 4 or α-tocopherol supplementation. We found that ferroptosis is responsible for APAP-induced hepatocyte cell death. Our findings provide new insights into the mechanism of APAP-induced hepatotoxicity and suggest that ferroptosis is a potential therapeutic target for APAP-induced acute liver failure.

Antinociceptive Efficacy of Retigabine and Flupirtine for Gout Arthritis Pain.

INTRODUCTION: Gout arthritis is an inflammatory disease characterized by severe acute pain. The goal of pharmacological gout arthritis treatments is to reduce pain, and thereby increase the patient's quality of life. The Kv7/M channel activators retigabine and flupirtine show analgesic efficacy in animal models of osteoarthritic pain. We hypothesized that these drugs may also alleviate gout arthritis pain. OBJECTIVE: To determine the effects of retigabine and flupirtine on pain behavior associated with monosodium urate (MSU)-induced gout arthritis. METHODS: The gout arthritis model was established with an intra-articular injection of MSU into the right ankle joint, animals were treated with retigabine or flupirtine, and pain-related behaviors were assessed. RESULTS: Retigabine and flupirtine significantly increased the mechanical threshold and prolonged the paw withdrawal latency in a rat model of gout arthritis pain in a dose-dependent manner. The antinociceptive effects of retigabine and flupirtine were fully antagonized by the Kv7/M channel blocker XE991. CONCLUSION: Retigabine and flupirtine showed antinociceptive effects for MSU-induced gout pain at different times during pain development.

N,N'-Diacetyl-p-phenylenediamine restores microglial phagocytosis and improves cognitive defects in Alzheimer's disease transgenic mice.

As a central feature of neuroinflammation, microglial dysfunction has been increasingly considered a causative factor of neurodegeneration implicating an intertwined pathology with amyloidogenic proteins. Herein, we report the smallest synthetic molecule (N,N'-diacetyl-p-phenylenediamine [DAPPD]), simply composed of a benzene ring with 2 acetamide groups at the para position, known to date as a chemical reagent that is able to promote the phagocytic aptitude of microglia and subsequently ameliorate cognitive defects. Based on our mechanistic investigations in vitro and in vivo, 1) the capability of DAPPD to restore microglial phagocytosis is responsible for diminishing the accumulation of amyloid-ß (Aß) species and significantly improving cognitive function in the brains of 2 types of Alzheimer's disease (AD) transgenic mice, and 2) the rectification of microglial function by DAPPD is a result of its ability to suppress the expression of NLRP3 inflammasome-associated proteins through its impact on the NF-κB pathway. Overall, our in vitro and in vivo investigations on efficacies and molecular-level mechanisms demonstrate the ability of DAPPD to regulate microglial function, suppress neuroinflammation, foster cerebral Aß clearance, and attenuate cognitive deficits in AD transgenic mouse models. Discovery of such antineuroinflammatory compounds signifies the potential in discovering effective therapeutic molecules against AD-associated neurodegeneration.

Ancient and modern anticonvulsants act synergistically in a KCNQ potassium channel binding pocket.

Epilepsy has been treated for centuries with herbal remedies, including leaves of the African shrub Mallotus oppositifolius, yet the underlying molecular mechanisms have remained unclear. Voltage-gated potassium channel isoforms KCNQ2-5, predominantly KCNQ2/3 heteromers, underlie the neuronal M-current, which suppresses neuronal excitability, protecting against seizures. Here, in silico docking, mutagenesis and cellular electrophysiology reveal that two components of M. oppositifolius leaf extract, mallotoxin (MTX) and isovaleric acid (IVA), act synergistically to open neuronal KCNQs, including KCNQ2/3 channels. Correspondingly, MTX and IVA combine to suppress pentylene tetrazole-induced tonic seizures in mice, whereas individually they are ineffective. Co-administering MTX and IVA with the modern, synthetic anticonvulsant retigabine creates a further synergy that voltage independently locks KCNQ2/3 open. Leveraging this synergy, which harnesses ancient and modern medicines to exploit differential KCNQ isoform preferences, presents an approach to developing safe yet effective anticonvulsants.

Cell growth potential drives ferroptosis susceptibility in rhabdomyosarcoma and myoblast cell lines.

PURPOSE: Ferroptosis is a programmed form of iron-dependent cell death caused by lipid hydroperoxide accumulation, which can be prevented by glutathione peroxidase 4 (GPx4) activity. Here we investigated the effects of ferroptosis inducers called erastin and RSL3, which act by glutathione depletion and GPx4 inactivation, respectively, on muscle-derived cell lines of embryonal and alveolar rhabdomyosarcoma (RMS), and mouse normal skeletal C2C12 myoblasts. METHODS: Myogenic lines were exposed to stepwise increasing concentrations of ferroptosis inducers either alone or in combination with iron supplementation, iron chelating agents (bathophenanthrolinedisulfonic acid, BPS), antioxidant molecules (glutathione, N-acetylcysteine), lipid peroxidation inhibitors (ferrostatin-1), and chemotherapeutic agents (doxorubicin and actinomycin D). Drug susceptibility was quantified by measuring cell viability, proliferation and differentiation via neutral red assay, crystal violet assay and Giemsa staining, respectively. The detection of lipid hydroperoxide and protein levels was performed by immunofluorescence and Western blot analysis, respectively. RESULTS: Erastin and RSL3 increased lipid hydroperoxide levels preferentially in the embryonal U57810 and myoblast C2C12 lines, leading to ferroptosis that was accentuated by iron supplementation or prevented by co-treatment with BPS, glutathione, N-acetylcysteine and ferrostatin-1. The inhibition of extracellular regulated kinases (ERK) pathway prevented ferroptosis in U57810 and C2C12 cells, whereas its increased activation in the embryonal RD cells mediated by caveolin-1 (Cav-1) overexpression led to augmented ferroptosis susceptibility. Finally, we observed the combination of erastin or RSL3 with chemotherapeutic doxorubicin and actinomycin D agents to be effective in increasing cell death in all RMS lines. CONCLUSIONS: Erastin and RSL3 trigger ferroptosis in highly proliferating myogenic lines through a ERK pathway-dependent fashion.

Pseudolaric acid B triggers ferroptosis in glioma cells via activation of Nox4 and inhibition of xCT.

Ferroptosis is a form of programmed cell death decided by iron-dependent lipid peroxidation, but its role in glioma cell death remains unclear. In this study, we found Pseudolaric acid B (PAB) inhibited the viabilities of glioma cells in vitro and in vivo, which was accompanied by abnormal increases of intracellular ferrous iron, H2O2 and lipid peroxidation, as well as depletion of GSH and cysteine. In vitro studies revealed that the lipid peroxidation and the cell death caused by PAB were both inhibited by iron chelator deferoxamine, but exacerbated by supplement of ferric ammonium citrate. Inhibition of lipid peroxidation with ferrostatin-1 or GSH rescued PAB-induced cell death. Morphologically, the cells treated with PAB presented intact membrane, shrunken mitochondria with increased membrane density, and normal-sized nucleus without chromatin condensation. Mechanistically, PAB improved intracellular iron by upregulation of transferrin receptor. The increased iron activated Nox4, which resulted in overproduction of H2O2 and lipid peroxides. Moreover, PAB depleted intracellular GSH via p53-mediated xCT pathway, which further exacerbated accumulation of H2O2 and lipid peroxides. Thus, PAB triggers ferroptosis in glioma cells and is a potential medicine for glioma treatment.

Heme oxygenase-1 mitigates ferroptosis in renal proximal tubule cells.

Ferroptosis is an iron-dependent form of regulated nonapoptotic cell death, which contributes to damage in models of acute kidney injury (AKI). Heme oxygenase-1 (HO-1) is a cytoprotective enzyme induced in response to cellular stress, and is protective against AKI because of its antiapoptotic and anti-inflammatory properties. However, the role of HO-1 in regulating ferroptosis is unclear. The purpose of this study was to elucidate the role of HO-1 in regulating ferroptotic cell death in renal proximal tubule cells (PTCs). Immortalized PTCs obtained from HO-1+/+ and HO-1-/- mice were treated with erastin or RSL3, ferroptosis inducers, in the presence or absence of antioxidants, an iron source, or an iron chelator. Cells were assessed for changes in morphology and metabolic activity as an indicator of cell viability. Treatment of HO-1+/+ PTCs with erastin resulted in a time- and dose-dependent increase in HO-1 gene expression and protein levels compared with vehicle-treated controls. HO-1-/- cells showed increased dose-dependent erastin- or RSL3-induced cell death in comparison to HO-1+/+ PTCs. Iron supplementation with ferric ammonium citrate in erastin-treated cells decreased cell viability further in HO-1-/- PTCs compared with HO-1+/+ cells. Cotreatment with ferrostatin-1 (ferroptosis inhibitor), deferoxamine (iron chelator), or N-acetyl-l-cysteine (glutathione replenisher) significantly increased cell viability and attenuated erastin-induced ferroptosis in both HO-1+/+ and HO-1-/- PTCs. These results demonstrate an important antiferroptotic role of HO-1 in renal epithelial cells.

Phytochemical investigations and evaluation of antimutagenic activity of the alcoholic extract of Glycosmis pentaphylla and Tabernaemontana coronaria by Ames test.

Chemical investigation of root bark of Glycosmis pentaphylla and stem bark of Tabernaemontana coronaria led to the isolation of three carbazole alkaloids glycozoline, glycozolidine and methyl carbazole 3-carboxylate, two furoquinoline alkaloids skimmianine and dictamine, an acridone alkaloid arborinine, three monomeric indole alkaloids coronaridine, 10-methoxy coronaridine and tabernaemontanine, and two dimeric indole alkaloids voacamine and tabernaelegantine B. Their structures were established by detailed spectral analysis. Mutagenic and antimutagenic potential of methanol extract of both plant materials were evaluated by Ames test against known positive mutagens 2-aminofluorine, 4-nitro-O-phenylenediamine and sodium azide using Salmonella typhimurium TA 98 and TA 100 bacterial strains both in the presence and absence of S9. Both the extracts were non-mutagenic in nature. Both the extracts of G. pentaphylla and T. coronaria exhibited significant antimutagenic activity against NPD and sodium azide for S. typhimurium TA98 and TA100 strains. The results indicated that the extracts could counteract the mutagenicity induced by different genotoxic compounds.

Kv7 voltage-activated potassium channel inhibitors reduce fluid resuscitation requirements after hemorrhagic shock in rats.

BACKGROUND: Recent evidence suggests that drugs targeting Kv7 channels could be used to modulate vascular function and blood pressure. Here, we studied whether Kv7 channel inhibitors can be utilized to stabilize hemodynamics and reduce resuscitation fluid requirements after hemorrhagic shock. METHODS: Anesthetized male Sprague-Dawley rats were instrumented with arterial and venous catheters for blood pressure monitoring, hemorrhage and fluid resuscitation. Series 1: Linopirdine (Kv7 channel blocker, 0.1-6 mg/kg) or retigabine (Kv7 channel activator, 0.1-12 mg/kg) were administered to normal animals. Series 2: Animals were hemorrhaged to a MAP of 25 mmHg for 30 min, followed by fluid resuscitation with normal saline (NS) to a MAP of 70 mmHg until t = 75 min. Animals were treated with single bolus injections of vehicle, linopirdine (1-6 mg/kg), XE-991 (structural analogue of linopirdine with higher potency for channel blockade, 1 mg/kg) prior to fluid resuscitation. Series 3: Animals were resuscitated with NS alone or NS supplemented with linopirdine (1.25-200 µg/mL). Data were analyzed with 2-way ANOVA/Bonferroni post-hoc testing. RESULTS: Series 1: Linopirdine transiently (10-15 min) and dose-dependently increased MAP by up to 15%. Retigabine dose-dependently reduced MAP by up to 60%, which could be reverted with linopirdine. Series 2: Fluid requirements to maintain MAP at 70 mmHg were 65 ± 34 mL/kg with vehicle, and 57 ± 13 mL/kg, 22 ± 8 mL/kg and 22 ± 11 mL/kg with intravenous bolus injection of 1, 3 and 6 mg/kg linopirdine, respectively. XE-991 (1 mg/kg), reduced resuscitation requirements comparable to 3 mg/kg linopirdine. Series 3: When resuscitation was performed with linopirdine-supplemented normal saline (NS), fluid requirements to stabilize MAP were 73 ± 12 mL/kg with NS alone and 72 ± 24, 61 ± 20, 36 ± 9 and 31 ± 9 mL/kg with NS supplemented with 1.25, 6.25, 12.5 and 200 µg/mL linopirdine, respectively. CONCLUSIONS: Our data suggest that Kv7 channel blockers could be used to stabilize blood pressure and reduce fluid resuscitation requirements after hemorrhagic shock.

Effect of a single dose of retigabine in cortical excitability parameters: A cross-over, double-blind placebo-controlled TMS study.

BACKGROUND: Antiepileptic drugs (AEDs) decrease the occurrence of epileptic seizures and modulate cortical excitability through several mechanisms that likely interact. The modulation of brain excitability by AEDs is believed to reflect their antiepileptic action(s) and could be used as a surrogate marker of their efficacy. Transcranial magnetic stimulation (TMS) is one of the best noninvasive methods to study cortical excitability in human subjects. Specific TMS parameters can be used to quantify the various mechanisms of action of AEDs. A new AED called retigabine increases potassium efflux by changing the conformation of KCNQ 2-5 potassium channels, which leads to neuronal hyperpolarisation and a decrease in excitability. HYPOTHESIS: The purpose of this study is to investigate the effect of retigabine on cortical excitability. Based on the known mechanisms of action of retigabine, we hypothesized that the oral intake of retigabine would increase the resting motor threshold (RMT). METHODS: Fifteen healthy individuals participated in a placebo-controlled, double-blind, randomised, clinical trial (RCT). The primary outcome measure was the RMT quantified before and after oral intake of retigabine. Several secondary TMS outcome measures were acquired. RESULTS: The mean RMT, active motor threshold (AMT) and intensity to obtain a 1mV peak-to-peak amplitude potential (SI1mV) were significantly increased after retigabine intake compared to placebo (RMT: P=0.039; AMT: P=0.014; SI1mV: P=0.019). No significant differences were found for short-interval intracortical inhibition/intracortical facilitation (SICI/ICF), long-interval intracortical inhibition (LICI) or short-interval intracortical facilitation (SICF). CONCLUSION: A single dose of retigabine increased the RMT, AMT and S1mV in healthy individuals. No modulating intracortical facilitation or inhibition was observed. This study provides the first in vivo demonstration of the modulating effects of retigabine on the excitability of the human brain, and the results are consistent with the data showing that retigabine hyperpolarizes neurons mainly by increasing potassium conductance.

[ANTHELMINTIC SUBSTANCES: MAIN CLASSES, PROBLEMS, TRENDS IN DEVELOPMENT AND PROSPECTS].

The review chronologically considers the main classes of the currently available anthelminthic substances: early anthelmintic compounds, benzimidazoles, imidazolthiazoles, tetrahydropyrimidines, avermectins and milbemycins, and salicylanilides. Great attention is paid to novel substances (emodepside, monepantel, derquantel, tribendimidine) and promising developments. Some aspects of the molecular mechanisms of action of anthelmintics, their resistance, and alternative dehelmintization methods are discussed.

Activation of neuronal Kv7/KCNQ/M-channels by the opener QO58-lysine and its anti-nociceptive effects on inflammatory pain in rodents.

AIM: The aim of this study was to examine the activation of neuronal Kv7/KCNQ channels by a novel modified Kv7 opener QO58-lysine and to test the anti-nociceptive effects of QO58-lysine on inflammatory pain in rodent models. METHODS: Assays including whole-cell patch clamp recordings, HPLC, and in vivo pain behavioral evaluations were employed. RESULTS: QO58-lysine caused instant activation of Kv7.2/7.3 currents, and increasing the dose of QO58-lysine resulted in a dose-dependent activation of Kv7.2/Kv7.3 currents with an EC50 of 1.2±0.2 µmol/L. QO58-lysine caused a leftward shift of the voltage-dependent activation of Kv7.2/Kv7.3 to a hyperpolarized potential at V1/2=-54.4±2.5 mV from V1/2=-26.0±0.6 mV. The half-life in plasma (t1/2) was derived as 2.9, 2.7, and 3.0 h for doses of 12.5, 25, and 50 mg/kg, respectively. The absolute bioavailabilities for the three doses (12.5, 25, and 50 mg/kg) of QO58-lysine (po) were determined as 13.7%, 24.3%, and 39.3%, respectively. QO58-lysine caused a concentration-dependent reduction in the licking times during phase II pain induced by the injection of formalin into the mouse hindpaw. In the Complete Freund's adjuvant (CFA)-induced inflammatory pain model in rats, oral or intraperitoneal administration of QO58-lysine resulted in a dose-dependent increase in the paw withdrawal threshold, and the anti-nociceptive effect on mechanical allodynia could be reversed by the channel-specific blocker XE991 (3 mg/kg). CONCLUSION: Taken together, our findings show that a modified QO58 compound (QO58-lysine) can specifically activate Kv7.2/7.3/M-channels. Oral or intraperitoneal administration of QO58-lysine, which has improved bioavailability and a half-life of approximately 3 h in plasma, can reverse inflammatory pain in rodent animal models.

Artemisinin derivatives induce iron-dependent cell death (ferroptosis) in tumor cells.

BACKGROUND: Apoptosis and other forms of cell death have been intensively investigated in the past years to explain the mode of action of synthetic anticancer drugs and natural products. Recently, a new form of cell death emerged, which was termed ferroptosis, because it depends on intracellular iron. Here, the role of genes involved in iron metabolism and homeostasis for the cytotoxicity of ten artemisinin derivatives have been systematically investigated. MATERIAL AND METHODS: Log10IC50 values of 10 artemisinin derivatives (artesunate, artemether, arteether, artenimol, artemisitene, arteanuin B, another monomeric artemisinin derivative and three artemisinin dimer molecules) were correlated to the microarray-based mRNA expression of 30 iron-related genes in 60 cell lines of the National Cancer Institute (NCI, USA) as determined in 218 different microarray hybridization experiments. The effect of desferoxamine and ferrostatin-1 on the cytotoxicity of artenimol of CCRF-CEM cells was determined by resazurin assays. The mRNA expression of TFRC was exemplarily validated by immunohistochemical detection of transferrin receptor protein expression. RESULTS: The mRNA expression of 20 genes represented by 59 different cDNA clones significantly correlated to the log10IC50 values for the artemisinins, including genes encoding transferrin (TF), transferrin receptors 1 and 2 (TFRC, TFR2), cerulopasmin (CP), lactoferrin (LTF) and others. The ferroptosis inhibitor ferrostatin-1 and the iron chelator deferoxamine led to a significantly reduced cytotoxicity of artenimol, indicating ferroptosis as cell death mode. CONCLUSION: The numerous iron-related genes, whose expression correlated with the response to artemisinin derivatives speak in factor for the relevance of iron for the cytotoxic activity of these compounds. Treatment with ferroptosis-inducing agents such as artemisinin derivatives represents an attractive strategy for cancer therapy. Pre-therapeutic determination of iron-related genes may indicate tumor sensitivity to artemisinins. Ferroptosis induced by artemisinin-type drugs deserve further investigation for individualized tumor therapy.

Thalamic Kv 7 channels: pharmacological properties and activity control during noxious signal processing.

BACKGROUND AND PURPOSE: The existence of functional K(v)7 channels in thalamocortical (TC) relay neurons and the effects of the K(+)-current termed M-current (I(M)) on thalamic signal processing have long been debated. Immunocytochemical evidence suggests their presence in this brain region. Therefore, we aimed to verify their existence, pharmacological properties and function in regulating activity in neurons of the ventrobasal thalamus (VB). EXPERIMENTAL APPROACH: Characterization of K(v)7 channels was performed by combining in vitro, in vivo and in silico techniques with a pharmacological approach. Retigabine (30 µM) and XE991 (20 µM), a specific K(v)7 channel enhancer and blocker, respectively, were applied in acute brain slices during electrophysiological recordings. The effects of intrathalamic injection of retigabine (3 mM, 300 nL) and/or XE991 (2 mM, 300 nL) were investigated in freely moving animals during hot-plate tests by recording behaviour and neuronal activity. KEY RESULTS: K(v)7.2 and K(v)7.3 subunits were found to be abundantly expressed in TC neurons of mouse VB. A slow K(+)-current with properties of IM was activated by retigabine and inhibited by XE991. K(v)7 channel activation evoked membrane hyperpolarization, a reduction in tonic action potential firing, and increased burst firing in vitro and in computational models. Single-unit recordings and pharmacological intervention demonstrated a specific burst-firing increase upon I(M) activation in vivo. A K(v)7 channel-mediated increase in pain threshold was associated with fewer VB units responding to noxious stimuli, and increased burst firing in responsive neurons. CONCLUSIONS AND IMPLICATIONS: K(v)7 channel enhancement alters somatosensory activity and may reflect an anti-nociceptive mechanism during acute pain processing.

Complementary functions of SK and Kv7/M potassium channels in excitability control and synaptic integration in rat hippocampal dentate granule cells.

The dentate granule cells (DGCs) form the most numerous neuron population of the hippocampal memory system, and its gateway for cortical input. Yet, we have only limited knowledge of the intrinsic membrane properties that shape their responses. Since SK and Kv7/M potassium channels are key mechanisms of neuronal spiking and excitability control, afterhyperpolarizations (AHPs) and synaptic integration, we studied their functions in DGCs. The specific SK channel blockers apamin or scyllatoxin increased spike frequency (excitability), reduced early spike frequency adaptation, fully blocked the medium-duration AHP (mAHP) after a single spike or spike train, and increased postsynaptic EPSP summation after spiking, but had no effect on input resistance (Rinput) or spike threshold. In contrast, blockade of Kv7/M channels by XE991 increased Rinput, lowered the spike threshold, and increased excitability, postsynaptic EPSP summation, and EPSP-spike coupling, but only slightly reduced mAHP after spike trains (and not after single spikes). The SK and Kv7/M channel openers 1-EBIO and retigabine, respectively, had effects opposite to the blockers. Computational modelling reproduced many of these effects. We conclude that SK and Kv7/M channels have complementary roles in DGCs. These mechanisms may be important for the dentate network function, as CA3 neurons can be activated or inhibition recruited depending on DGC firing rate.

The discovery and optimization of novel dual inhibitors of topoisomerase II and histone deacetylase.

A novel class of podophyllotoxin derivatives have been designed and synthesized based on the synergistic antitumor effects of topoisomerase II and histone deacetylase inhibitors. Their inhibitory activities towards histone deacetylases and Topo II and their cytotoxicities in cancer cell lines were evaluated. The aromatic capping group connection, linker length and zinc-binding group were systematically varied and preliminary conclusions regarding structure-activity relationships are discussed. Among all of the synthesized hybrid compounds, compound 24 d showed the most potent HDAC inhibitory activity at a low nanomolar level and exhibited powerful antiproliferative activity towards HCT116 colon carcinoma cells at a low micromolar level. Further exploration of this series led to the discovery of potent dual inhibitor 32, which exhibited the strongest in vitro cytotoxic activity.