Antitumor efficacy of CHMFL-KIT-110 solid dispersion in mouse xenograft models of human gastrointestinal stromal tumors.

PURPOSE: CHMFL-KIT-110, a selective c-KIT kinase inhibitor for gastrointestinal stromal tumors (GISTs), possesses a poorly water-soluble, limiting the further development of the drug. This study was to investigate the antitumor efficacy of CHMFL-KIT-110 and CHMFL-KIT-110 solid dispersion (laboratory code: HYGT-110 SD) in GIST tumor xenograft models and to explore the PK/PD relationship of HYGT-110 SD. METHODS: Plasma concentrations of HYGT-110 and HYGT-110 SD were determined by LC-MS/MS in KM mice. Antitumor activity was evaluated by measuring tumor volume and weight in c-KIT-dependent GIST xenograft models. PK/PD relationship was assessed by LC-MS/MS and Western Blot in the GIST-T1 xenografted mice. RESULTS: HYGT-110 exhibited a low oral bioavailability (10.91%) in KM mice. Compared with HYGT-110 treatment, the Cmax and AUC0-t of HYGT-110 SD in mice plasma were substantially increased by 18.81 and 6.76-fold, respectively. HYGT-110 SD (10, 30, and 100 mg/kg/day) also could dose-dependently decrease the tumor volume and weight in the GIST-882 cell-inoculated xenograft mouse models and show 86.35% tumor growth inhibition (TGI) at 28 days at a 25 mg/kg bid dosage in the GIST-T1 cell-inoculated xenograft mouse model. The free concentration of HYGT-110 in plasma was closely correlated with the inhibition of c-KIT phosphorylation levels in tumor tissues. CONCLUSIONS: In comparison with the HPMC formulation, both improved PK and PD characteristics of the solid dispersion formulation of CHMFL-KIT-110 were observed in in vivo animal experiments.

Selective inhibition of JAK3 signaling is sufficient to reverse alopecia areata.

The Janus kinase/signal transducers and activators of transcription (JAK/STAT) are key intracellular mediators in the signal transduction of many cytokines and growth factors. Common γ chain cytokines and interferon-γ that use the JAK/STAT pathway to induce biological responses have been implicated in the pathogenesis of alopecia areata (AA), a T cell-mediated autoimmune disease of the hair follicle. We previously showed that therapeutic targeting of JAK/STAT pathways using the first-generation JAK1/2 inhibitor, ruxolitinib, and the pan-JAK inhibitor, tofacitinib, was highly effective in the treatment of human AA, as well as prevention and reversal of AA in the C3H/HeJ mouse model. To better define the role of individual JAKs in the pathogenesis of AA, in this study, we tested and compared the efficacy of several next-generation JAK-selective inhibitors in the C3H/HeJ mouse model of AA, using both systemic and topical delivery. We found that JAK1-selective inhibitors as well as JAK3-selective inhibitors robustly induced hair regrowth and decreased AA-associated inflammation, whereas several JAK2-selective inhibitors failed to restore hair growth in treated C3H/HeJ mice with AA. Unlike JAK1, which is broadly expressed in many tissues, JAK3 expression is largely restricted to hematopoietic cells. Our study demonstrates inhibiting JAK3 signaling is sufficient to prevent and reverse disease in the preclinical model of AA.

Crystal structures of two inhibitors in complex with histone lysine demethylase 4D (KDM4D) provide new insights for rational drug design.

Histone lysine demethylase 4D (KDM4D), also known as JMJD2D, plays an important role in cell proliferation and survival and has been associated with several tumor types. KDM4D has emerged as a potential target for the treatment of human cancer. Here, we reported crystal complex structures for two KDM4D inhibitors, OWS [2-(1H-pyrazol-3-yl)isonicotinic acid] and 10r (5-hydroxy-2-methylpyrazolo[1,5-a]pyrido[3,2-e]pyrimidine-3-carbonitrile), which were both determined to 2.0 Å. OWS is a newly discovered KDM4D inhibitor (IC50 = 4.28 µM) and the critical pharmacophores of this compound are confirmed by the complex structure. Compound 10r is a KDM4D inhibitor reported by us previously. To clarify the binding mode in more detail, the crystal structure was determined and the comparison analysis revealed unique interactions that had never been observed before. Overall, our data provide new structural insights for rational design and offer an opportunity for optimization of KDM4D inhibitors.

Intestine-specific FXR agonists as potential therapeutic agents for colorectal cancer.

Colorectal cancer (CRC) is one of the most malignant cancers in the world. A major cause of death in CRC patients is the limited therapeutic options in its advanced stages. The Farnesoid X receptor (FXR) is a member of the nuclear superfamily, which is effective in slowing the progression of colorectal cancer in addition to its extraordinary role in regulating metabolic disorders. Due to the systemic side-effects caused by non-selective agonists, the intestine-restricted FXR agonists can induce a whole-body benefit without activating the hepatic FXR, suggesting intestinal FXR activation as a potentially safer therapy in the treatment of CRC. This review highlights the effects of FXR on the disturbed bile acid circulation and the carcinogenesis of CRC and with a specific emphasis on listing the functions of several intestinal-restricted FXR agonists.

Itacitinib (INCB039110), a JAK1 Inhibitor, Reduces Cytokines Associated with Cytokine Release Syndrome Induced by CAR T-cell Therapy.

PURPOSE: T cells engineered to express a chimeric antigen receptor (CAR) are a promising cancer immunotherapy. Such targeted therapies have shown long-term relapse-free survival in patients with B-cell leukemia and lymphoma. However, cytokine release syndrome (CRS) represents a serious, potentially life-threatening side effect often associated with CAR T-cell therapy. CRS manifests as a rapid (hyper)immune reaction driven by excessive inflammatory cytokine release, including IFNγ and IL6. EXPERIMENTAL DESIGN: Many cytokines implicated in CRS are known to signal through the JAK-STAT pathway. Here we study the effect of blocking JAK pathway signaling on CAR T-cell proliferation, antitumor activity, and cytokine levels in in vitro and in vivo models. RESULTS: We report that itacitinib, a potent, selective JAK1 inhibitor, was able to significantly and dose-dependently reduce levels of multiple cytokines implicated in CRS in several in vitro and in vivo models. Importantly, we also report that at clinically relevant doses that mimic human JAK1 pharmacologic inhibition, itacitinib did not significantly inhibit proliferation or antitumor killing capacity of three different human CAR T-cell constructs (GD2, EGFR, and CD19). Finally, in an in vivo model, antitumor activity of CD19-CAR T cells adoptively transferred into CD19+ tumor-bearing immunodeficient animals was unabated by oral itacitinib treatment. CONCLUSIONS: Together, these data suggest that itacitinib has potential as a prophylactic agent for the prevention of CAR T cell-induced CRS, and a phase II clinical trial of itacitinib for prevention of CRS induced by CAR T-cell therapy has been initiated (NCT04071366).

Sulfamic acid catalyzed synthesis of new 3,5-[(sub)phenyl]-1H-pyrazole bearing N1-isonicotinoyl: And their pharmacological activity evaluation.

A sustainable synthesis of new 3,5-[(sub)phenyl]-1H-pyrazole bearing N1-isonicotinoyl derivatives from substituted chalcones and isoniazid by using sulfamic acid and their pharmacological activity evaluation is reported. An anti-oxidant study is performed by using DPPH assay. In vitro anti-mycobacterial activity of compounds bearing R/R' = 4-CH3/4-F and 3-OCH3/4-Cl showed complete inhibition (99%) at the MIC of 31 and 34 µM respectively. Antibacterial screening of compounds bearing R/R' = 4-CH3/4-F; 4-OCH3/4-Br; and 4-OCH3/4-Cl has shown noticeable inhibition (27 mm) against Staphylococcus aureus. The anti-cancer bioassay demonstrated that the five compounds were active on human breast cancer cell line MCF-7; however on HeLa cervical cancer cells only two compounds are active in comparison to standard drug Doxorubicin. Higher inhibitory effects observed in this study appear to be dependent on the chloro, bromo, fluoro and methoxy functionality present on the aromatic nucleus. The structures of all the compounds are established using NMR (1H and 13C), FT-IR, Mass and elemental analysis.

Preclinical characterization of itacitinib (INCB039110), a novel selective inhibitor of JAK1, for the treatment of inflammatory diseases.

Pharmacological modulation of the Janus kinase (JAK) family has achieved clinically meaningful therapeutic outcomes for the treatment of inflammatory and hematopoietic diseases. Several JAK1 selective compounds are being investigated clinically to determine their anti-inflammatory potential. We used recombinant enzymes and primary human lymphocytes to assess the JAK1 specificity of itacitinib (INCB039110) and study inhibition of signal transducers and activators of transcription (STAT) signaling. Rodent models of arthritis and inflammatory bowel disease were subsequently explored to elucidate the efficacy of orally administered itacitinib on inflammatory pathogenesis. Itacitinib is a potent and selective JAK1 inhibitor when profiled against the other JAK family members. Upon oral administration in rodents, itacitinib achieved dose-dependent pharmacokinetic exposures that highly correlated with STAT3 pharmacodynamic pathway inhibition. Itacitinib ameliorated symptoms and pathology of established experimentally-induced arthritis in a dose-dependent manner. Furthermore, itacitinib effectively delayed disease onset, reduced symptom severity, and accelerated recovery in three distinct mouse models of inflammatory bowel disease. Low dose itacitinib administered via cannula directly into the colon was highly efficacious in TNBS-induced colitis but with minimal systemic drug exposure, suggesting localized JAK1 inhibition is sufficient for disease amelioration. Itacitinib treatment in an acute graft-versus-host disease (GvHD) model rapidly reduced inflammatory markers within lymphocytes and target tissue, resulting in a marked improvement in disease symptoms. This is the first manuscript describing itacitinib as a potent and selective JAK1 inhibitor with anti-inflammatory activity across multiple preclinical disease models. These data support the scientific rationale for ongoing clinical trials studying itacitinib in select GvHD patient populations.

Cilofexor, a Nonsteroidal FXR Agonist, in Patients With Noncirrhotic NASH: A Phase 2 Randomized Controlled Trial.

BACKGROUND AND AIMS: We evaluated the safety and efficacy of cilofexor (formerly GS-9674), a small-molecule nonsteroidal agonist of farnesoid X receptor, in patients with nonalcoholic steatohepatitis (NASH). APPROACH AND RESULTS: In this double-blind, placebo-controlled, phase 2 trial, 140 patients with noncirrhotic NASH, diagnosed by magnetic resonance imaging-proton density fat fraction (MRI-PDFF) ≥8% and liver stiffness ≥2.5 kPa by magnetic resonance elastography (MRE) or historical liver biopsy, were randomized to receive cilofexor 100 mg (n = 56), 30 mg (n = 56), or placebo (n = 28) orally once daily for 24 weeks. MRI-PDFF, liver stiffness by MRE and transient elastography, and serum markers of fibrosis were measured at baseline and week 24. At baseline, median MRI-PDFF was 16.3% and MRE-stiffness was 3.27 kPa. At week 24, patients receiving cilofexor 100 mg had a median relative decrease in MRI-PDFF of -22.7%, compared with an increase of 1.9% in those receiving placebo (P = 0.003); the 30-mg group had a relative decrease of -1.8% (P = 0.17 vs. placebo). Declines in MRI-PDFF of ≥30% were experienced by 39% of patients receiving cilofexor 100 mg (P = 0.011 vs. placebo), 14% of those receiving cilofexor 30 mg (P = 0.87 vs. placebo), and 13% of those receiving placebo. Serum gamma-glutamyltransferase, C4, and primary bile acids decreased significantly at week 24 in both cilofexor treatment groups, whereas significant changes in Enhanced Liver Fibrosis scores and liver stiffness were not observed. Cilofexor was generally well-tolerated. Moderate to severe pruritus was more common in patients receiving cilofexor 100 mg (14%) than in those receiving cilofexor 30 mg (4%) and placebo (4%). CONCLUSIONS: Cilofexor for 24 weeks was well-tolerated and provided significant reductions in hepatic steatosis, liver biochemistry, and serum bile acids in patients with NASH. ClinicalTrials.gov No. NCT02854605.

Regulation and role of endoglin in cholesterol-induced endothelial and vascular dysfunction in vivo and in vitro.

Our objective was to investigate the effect of cholesterol [hypercholesterolemia and 7-ketocholesterol (7K)] on endoglin (Eng) expression and regulation with respect to endothelial or vascular dysfunction in vivo and in vitro. In vivo experiments were performed in 2-mo-old atherosclerosis-prone apolipoprotein E-deficient/LDL receptor-deficient (ApoE-/-/LDLR-/-) female mice and their wild-type C57BL/6J littermates. In in vitro experiments, human aortic endothelial cells (HAECs) were treated with 7K. ApoE-/-/LDLR-/- mice developed hypercholesterolemia accompanied by increased circulating levels of P-selectin and Eng and a disruption of NO metabolism. Functional analysis of the aorta demonstrated impaired vascular reactivity, and Western blot analysis revealed down-regulation of membrane Eng/Smad2/3/eNOS signaling in ApoE-/-/LDLR-/- mice. 7K increased Eng expression via Krüppel-like factor 6 (KLF6), liver X nuclear receptor, and NF-κB in HAECs. 7K-induced Eng expression was prevented by the treatment with 2-hydroxypropyl-ß-cyclodextrin; 8-{[5-chloro-2-(4-methylpiperazin-1-yl) pyridine-4-carbonyl] amino}-1-(4-fluorophenyl)-4, 5-dihydrobenzo[g]indazole-3-carboxamide; or by KLF6 silencing. 7K induced increased adhesion and transmigration of monocytic human leukemia promonocytic cell line cells and was prevented by Eng silencing. We concluded that hypercholesterolemia altered Eng expression and signaling, followed by endothelial or vascular dysfunction before formation of atherosclerotic lesions in ApoE-/-/LDLR-/- mice. By contrast, 7K increased Eng expression and induced inflammation in HAECs, which was followed by an increased adhesion and transmigration of monocytes via endothelium, which was prevented by Eng inhibition. Thus, we propose a relevant role for Eng in endothelial or vascular dysfunction or inflammation when exposed to cholesterol.-Vicen, M., Vitverova, B., Havelek, R., Blazickova, K., Machacek, M., Rathouska, J., Najmanová, I., Dolezelova, E., Prasnicka, A., Sternak, M., Bernabeu, C., Nachtigal, P. Regulation and role of endoglin in cholesterol-induced endothelial and vascular dysfunction in vivo and in vitro.

Eugenol, a Plant Volatile, Synergizes the Effect of the Thrips Attractant, Ethyl Iso-Nicotinate.

The onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a polyphagous pest that causes serious damage to agricultural crops, vegetables, and ornamental plants worldwide. Farmers rely on the extensive usage of synthetic chemical insecticides to control T. tabaci. There is a dire need to develop alternative control strategies to overcome the problems posed by chemical insecticides. Efficient traps would allow sensitive monitoring and possibly mass trapping. A field experiment was conducted to evaluate the potential of three plant compounds with known release rates (ranging from 6-30 mg/d); eugenol (Eug), 1, 8-cineole (eucalyptol), and linalool in all possible combinations with a thrips attractant, ethyl iso-nicotinate (EI). A combination of EI with Eug increased the effect of EI by attracting 100% more thrips (effect size, 1.95) as compared to the control of EI alone. Catches in remaining treatments were lower and or not significantly different from EI alone. The results from our study could be used to develop improved volatile blends to be used for monitoring traps. Our data suggests that these traps could be effective even at very low populations.

Mycobacterium tuberculosis Is Selectively Killed by Rifampin and Rifapentine in Hypoxia at Neutral pH.

The activities of rifampin, rifapentine, bedaquiline, PA-824, clofazimine, nitazoxanide, isoniazid, amikacin, moxifloxacin, niclosamide, thioridazine, and pyrazinamide were tested against nonreplicating (dormant) Mycobacterium tuberculosis H37Rv under conditions of hypoxia at pHs 5.8 and 7.3, mimicking environments of cellular granulomas and caseous granulomas, respectively. At pH 5.8, several drugs killed dormant bacilli, with the best being rifampin and rifapentine. At pH 7.3, only rifampin and rifapentine efficiently killed dormant bacilli, while all other drugs showed little activity.

Investigating the Role of Loop C Hydrophilic Residue 'T244' in the Binding Site of ρ1 GABAC Receptors via Site Mutation and Partial Agonism.

The loop C hydrophilic residue, threonine 244 lines the orthosteric binding site of ρ1 GABAC receptors was studied by point mutation into serine, alanine and cysteine, and tested with GABA, some representative partial agonists and antagonists. Thr244 has a hydroxyl group essential for GABA activity that is constrained by the threonine methyl group, orienting it toward the binding site. Significant decreases in activation effects of the studied ligands at ρ1 T244S mutant receptors, suggests a critical role for this residue. Results of aliphatic and heteroaromatic partial agonists demonstrate different pharmacological effects at ρ1 T244S mutant receptors when co-applied with GABA EC50 responses. ρ1 T244A and ρ1 T244C mutant receptors have minimal sensitivity to GABA at high mM concentrations, whereas, the ρ1 WT partial agonists, ß-alanine and MTSEA demonstrate more efficacy and potency, respectively, than GABA at these mutant receptors. This study explores the role of Thr244 in the binding of agonists as an initial step during channel gating by moving loop C towards the ligand.

Characterization of cytoprotective and toxic properties of iron chelator SIH, prochelator BSIH and their degradation products.

Free cellular iron catalyzes the formation of toxic hydroxyl radicals and therefore chelation of iron could be a promising therapeutic approach in pathological states associated with oxidative stress. Salicylaldehyde isonicotinoyl hydrazone (SIH) is a strong intracellular iron chelator with well documented potential to protect against oxidative damage both in vitro and in vivo. Due to the short biological half-life of SIH and risk of toxicity due to iron depletion, boronate prochelator BSIH has been designed. BSIH cannot bind iron until it is activated by certain reactive oxygen species to active chelator SIH. The aim of this study was to examine the toxicity and cytoprotective potential of BSIH, SIH, and their decomposition products against hydrogen peroxide-induced injury of H9c2 cardiomyoblast cells. Using HPLC, we observed that salicylaldehyde was the main decomposition products of SIH and BSIH, although a small amount of salicylic acid was also detected. In the case of BSIH, the concentration of formed salicylaldehyde consistently exceeded that of SIH. Isoniazid and salicylic acid were not toxic nor did they provide any antioxidant protective effect in H9c2 cells. In contrast, salicylaldehyde was able to chelate intracellular iron and significantly preserve cellular viability and mitochondrial inner membrane potential induced by hydrogen peroxide. However it was consistently less effective than SIH. The inherent toxicities of salicylaldehyde and SIH were similar. Hence, although SIH - the active chelating agent formed following the BSIH activation - undergoes rapid hydrolysis, its principal decomposition product salicylaldehyde accounts markedly for both cytoprotective and toxic properties.

Discovery of N-(3-((1-Isonicotinoylpiperidin-4-yl)oxy)-4-methylphenyl)-3-(trifluoromethyl)benzamide (CHMFL-KIT-110) as a Selective, Potent, and Orally Available Type II c-KIT Kinase Inhibitor for Gastrointestinal Stromal Tumors (GISTs).

c-KIT kinase is a validated drug discovery target for gastrointestinal stromal tumors (GISTs). Clinically used c-KIT kinase inhibitors, i.e., Imatinib and Sunitinib, bear other important targets such as ABL or FLT3 kinases. Here we report our discovery of a more selective c-KIT inhibitor, compound 13 (CHMFL-KIT-110), which completely abolished ABL and FLT3 kinase activity. KinomeScan selectivity profiling (468 kinases) of 13 exhibited a high selectivity (S score (1) = 0.01). 13 displayed great antiproliferative efficacy against GISTs cell lines GIST-T1 and GIST-882 (GI50: 0.021 and 0.043 µM, respectively). In the cellular context, it effectively affected c-KIT-mediated signaling pathways and induced apoptosis as well as cell cycle arrest. In addition, 13 possessed acceptable bioavailability (36%) and effectively suppressed the tumor growth in GIST-T1 cell inoculated xenograft model without apparent toxicity. 13 currently is undergoing extensive preclinical evaluation and might be a potential drug candidate for GISTs.

Substituted 2-(2-aminopyrimidin-4-yl)pyridine-4-carboxylates as potent inhibitors of JumonjiC domain-containing histone demethylases.

BACKGROUND: Aberrant expression of iron(II)- and 2-oxoglutarate-dependent JumonjiC histone demethylases has been linked to cancer. Potent demethylase inhibitors are drug candidates and biochemical tools to elucidate the functional impact of demethylase inhibition. METHODS & RESULTS: Virtual screening identified a novel lead scaffold against JMJD2A with low-micromolar potency in vitro. Analogs were acquired from commercial sources respectively synthesized in feedback with biological testing. Optimized compounds were transformed into cell-permeable prodrugs. A cocrystal x-ray structure revealed the mode of binding of these compounds as competitive to 2-oxoglutarate and confirmed kinetic experiments. Selectivity studies revealed a preference for JMJD2A and JARID1A over JMJD3. CONCLUSION: Virtual screening and rational structural optimization led to a novel scaffold for highly potent and selective JMJD2A inhibitors.

Esters of the marine-derived triterpene sipholenol A reverse P-GP-mediated drug resistance.

Our previous studies showed that several sipholane triterpenes, sipholenol A, sipholenone E, sipholenol L and siphonellinol D, have potent reversal effect for multidrug resistance (MDR) in cancer cells that overexpressed P-glycoprotein (P-gp/ABCB1). Through comparison of cytotoxicity towards sensitive and multi-drug resistant cell lines, we identified that the semisynthetic esters sipholenol A-4-O-acetate and sipholenol A-4-O-isonicotinate potently reversed P-gp-mediated MDR but had no effect on MRP1/ABCC1 and BCRP/ABCG2-mediated MDR. The results from [3H]-paclitaxel accumulation and efflux studies suggested that these two triterpenoids were able to increase the intracellular accumulation of paclitaxel by inhibiting its active efflux. In addition, western blot analysis revealed that these two compounds did not alter the expression levels of P-gp when treated up to 72 h. These sipholenol derivatives also stimulated the ATPase activity of P-gp membranes, which suggested that they might be substrates of P-gp. Moreover, in silico molecular docking studies revealed the virtual binding modes of these two compounds into human homology model of P-gp. In conclusion, sipholenol A-4-O-acetate and sipholenol A-4-O-isonicotinate efficiently inhibit the P-gp and may represent potential reversal agents for the treatment of multidrug resistant cancers.

Orai1 protein expression and the role of calcium release-activated calcium channels in the contraction of human term-pregnant and non-pregnant myometrium.

AIM: This experimental in vitro study examined differences in the expression and activity of calcium release-activated calcium (CRAC) channels of human term-pregnant and non-pregnant myometrium. MATERIAL AND METHODS: The tissue samples were obtained from term-pregnant myometrium in labor of women undergoing cesarean section and from non-pregnant myometrium of women undergoing total hysterectomy due to uterine myoma. The expression of Orai1 protein, a pore-forming subunit of CRAC channels, in human myometrium was examined using immunohistochemistry. CRAC channel involvement in the amplitude and frequency of myometrial contractions was evaluated in vitro using a tissue bath method with a CRAC ion channel blocker 3-fluropyridine-4-carboxylic acid (FPCA). RESULTS: Decreased Orai1 expression was observed in human term-pregnant laboring myometrium compared with non-pregnant myometrium. However, the initial oxytocin-induced contraction of myometrium was significantly suppressed at different doses of FPCA in both non-pregnant human isolated myometrium and non-pregnant myometrium. The frequency of contractions was the most significantly reduced at the lowest dose of FPCA in non-pregnant myometrium and remained suppressed at all doses of FPCA in term-pregnant myometrium. Salbutamol was shown as more effective in suppression of amplitude in term-pregnant isolated myometrium. CONCLUSION: Our results provide the first information about the changes in the Orai1 protein expression and activity of human myometrial CRAC channels in term-pregnant laboring myometrium.

Spontaneous swallowing occurs during autoresuscitation in the in situ brainstem preparation of rat.

Previous studies report that upper airway reflexes are operational during autoresuscitation from respiratory arrest. We investigated swallowing/breathing interactions, measured by recording of vagal (VNA) and phrenic nerve activities (PNA), during autoresuscitation in the in situ perfused brainstem preparation of juvenile rats. During the initial surgery, respiratory arrest was induced by exsanguination and cooling. Reperfusion (i.e. re-oxygenation and re-warming) of the brainstem circuits was associated with frequent spontaneous swallowing before resumption of respiration (n=6, 'stage 1 autoresuscitation'). When recovered, the respiratory pattern was transiently apneustic-like ('stage 2 autoresuscitation'). Spontaneous swallowing often occurred at the end of the prolonged PNA (n=9/12). Successful autoresuscitation was characterised by re-establishment of the 3 phase respiratory motor pattern and no spontaneous swallowing. Pharmacological inhibition (isoguvacine, 10 mM, 50-75 nl; n=10) of the Kölliker-Fuse nucleus (KF) mimicked stage 2 autoresuscitation. However, the frequency of spontaneous swallowing after KF inhibition did not correlate with subsequent recovery of the eupneic respiratory motor pattern.

Comparison of various iron chelators and prochelators as protective agents against cardiomyocyte oxidative injury.

Oxidative stress is a common denominator of numerous cardiovascular disorders. Free cellular iron catalyzes the formation of highly toxic hydroxyl radicals, and iron chelation may thus be an effective therapeutic approach. However, using classical iron chelators in diseases without iron overload poses risks that necessitate more advanced approaches, such as prochelators that are activated to chelate iron only under disease-specific oxidative stress conditions. In this study, three cell-membrane-permeable iron chelators (clinically used deferasirox and experimental SIH and HAPI) and five boronate-masked prochelator analogs were evaluated for their ability to protect cardiac cells against oxidative injury induced by hydrogen peroxide. Whereas the deferasirox-derived agents TIP and TRA-IMM displayed negligible protection and even considerable toxicity, the aroylhydrazone prochelators BHAPI and BSIH-PD provided significant cytoprotection and displayed lower toxicity after prolonged cellular exposure compared to their parent chelators HAPI and SIH, respectively. Overall, the most favorable properties in terms of protective efficiency and low inherent cytotoxicity were observed with the aroylhydrazone prochelator BSIH. BSIH efficiently protected both H9c2 rat cardiomyoblast-derived cells and isolated primary rat cardiomyocytes against hydrogen peroxide-induced mitochondrial and lysosomal dysregulation and cell death. At the same time, BSIH was nontoxic at concentrations up to its solubility limit (600 µM) and in 72-h incubation. Hence, BSIH merits further investigation for prevention and/or treatment of cardiovascular disorders associated with a known (or presumed) component of oxidative stress.

Linking γ-aminobutyric acid A receptor to epidermal growth factor receptor pathways activation in human prostate cancer.

Neuroendocrine (NE) differentiation has been attributed to the progression of castration-resistant prostate cancer (CRPC). Growth factor pathways including the epidermal growth factor receptor (EGFR) signaling have been implicated in the development of NE features and progression to a castration-resistant phenotype. However, upstream molecules that regulate the growth factor pathway remain largely unknown. Using androgen-insensitive bone metastasis PC-3 cells and androgen-sensitive lymph node metastasis LNCaP cells derived from human prostate cancer (PCa) patients, we demonstrated that γ-aminobutyric acid A receptor (GABA(A)R) ligand (GABA) and agonist (isoguvacine) stimulate cell proliferation, enhance EGF family members expression, and activate EGFR and a downstream signaling molecule, Src, in both PC-3 and LNCaP cells. Inclusion of a GABA(A)R antagonist, picrotoxin, or an EGFR tyrosine kinase inhibitor, Gefitinib (ZD1839 or Iressa), blocked isoguvacine and GABA-stimulated cell growth, trans-phospohorylation of EGFR, and tyrosyl phosphorylation of Src in both PCa cell lines. Spatial distributions of GABAAR α1 and phosphorylated Src (Tyr416) were studied in human prostate tissues by immunohistochemistry. In contrast to extremely low or absence of GABA(A)R α1-positive immunoreactivity in normal prostate epithelium, elevated GABA(A)R α1 immunoreactivity was detected in prostate carcinomatous glands. Similarly, immunoreactivity of phospho-Src (Tyr416) was specifically localized and limited to the nucleoli of all invasive prostate carcinoma cells, but negative in normal tissues. Strong GABAAR α1 immunoreactivity was spatially adjacent to the neoplastic glands where strong phospho-Src (Tyr416)-positive immunoreactivity was demonstrated, but not in adjacent to normal glands. These results suggest that the GABA signaling is linked to the EGFR pathway and may work through autocrine or paracine mechanism to promote CRPC progression.