Kinetics of Dextromethorphan-O-Demethylase Activity and Distribution of CYP2D in Four Commonly-Used Subcellular Fractions of Rat Brain

The purpose of this study was to compare the enzymatic kinetics and distribution of cytochrome P450 2D (CYP2D) among different rat brain subcellular fractions. Rat brains were used to prepare total membrane, crude mitochondrial, purified mitochondrial, and microsomal fractions, in addition to total homogenate. Michaelis–Menten kinetics of the brain CYP2D activity was estimated based on the conversion of dextromethorphan (DXM) to dextrorphan using UPLC-MS/MS. Protein levels of CYP2D and subcellular markers were determined by Western blot. Microsomal CYP2D exhibited high affinity and low capacity, compared with the mitochondrial CYP2D that had a much lower (∼50-fold) affinity but a higher (∼six-fold) capacity. The apparent CYP2D affinity and capacity of the crude mitochondria were in between those of the microsomes and purified mitochondria. Additionally, the CYP2D activity in the whole homogenate was much higher than that in the total membranes at higher DXM concentrations. A CYP2D immune-reactive band in the brain mitochondria appeared at a lower MW but had a much higher intensity than that in the microsomes. Mitochondrial brain CYP2D has a much higher capacity than its microsomal counterpart. Additionally, brain homogenate is more representative of the overall CYP2D activity than the widely-used total membrane fraction

A Comparison of Calcium Aggregation and Ultracentrifugation Methods for the Preparation of Rat Brain Microsomes for Drug Metabolism Studies

Preparation of brain microsomes by the calcium chloride aggregation method has been suggested as an alternative to the ultracentrifugation method. However, the effects of the calcium chloride concentration on the quality of the microsomal fractions are not known. Brain microsomes were prepared from the adult rat brains using the high-speed ultracentrifugation and low-speed calcium chloride (10–100 mM) aggregation methods (n = 5–6 per group). The microsomal protein yield (spectrometry), the cytochrome P450 reductase (CPR) activity (spectrometry), and the monooxygenase activities (UPLC-MS/MS) of CYP2D and CYP2E1 were determined in the obtained fractions. Increasing the concentrations of calcium chloride progressively increased the protein yield of the low-speed microsomal fractions. However, the increased yield was associated with a significant decrease in the activities of CPR, CYP2D, and CYP2E1. Additionally, the CYP2D and CYP2E1 activities were significantly correlated with the CPR activities of the fractions. In conclusion, when an ultracentrifuge is available, preparation of brain microsomes by the ultracentrifugation method might be preferable. However, the calcium aggregation method at a calcium chloride concentration of 10 mM is an acceptable alternative to the ultracentrifuge method

Hypertrophic and Fibrotic Human PKD Hearts are Associated with Macrophage Infiltration and Abnormal TGF-β1 Signaling

Autosomal dominant polycystic kidney disease (PKD) is a hereditary kidney disorder which can affect cardiovascular system. Cardiac hypertrophy and cardiomyopathy in PKD have been reported by echocardiography analyses, but histopathology analyses of human PKD hearts have never been examined. The current studies evaluated human heart tissues from five subjects without PKD (non-PKD) and five subjects with PKD. Our histopathology data of human PKD hearts showed an increased extracellular matrix associated with cardiac hypertrophy and fibrosis. Hypertrophy- and fibrosis-associated pathways involving abnormal cardiac structure were next analyzed. We found that human PKD myocardium was infiltrated by inflammatory macrophage M1 and M2; expression of transforming growth factor (TGF-β1) and its receptor were upregulated with overexpression of pSmad3 and β-catenin. Because patients with PKD have an abnormal kidney function that could potentially affect heart structure, we used a heart-specific PKD mouse model to validate that cardiac hypertrophy and fibrosis were independent from polycystic kidney. In summary, our data show that hearts from human PKD were characterized by hypertrophy, interstitial fibrosis, perivascular fibrosis, and conduction system fibrosis with upregulated TGF-β1 and its receptor. We suggest that such structural abnormalities may predispose to systolic and diastolic cardiac dysfunction in the PKD myocardium

Arrhythmogenic Hearts in PKD2 Mutant Mice Are Characterized by Cardiac Fibrosis, Systolic, and Diastolic Dysfunctions

Autosomal dominant polycystic kidney disease (PKD) is a hereditary disorder affecting multiple organs, including the heart. PKD has been associated with many cardiac abnormalities including the arrhythmogenic remodeling in clinical evaluations. In our current study, we hypothesized that Pkd2 gene mutation results in structural and functional defects in the myocardium. The structural and functional changes of Pkd2 mutant hearts were analyzed in the myocardial-specific Pkd2 knockout (KO) mouse. We further assessed a potential role of TGF-b1 signaling in the pathology of Pkd2-KO hearts. Hearts from age-matched 6-month-old MyH6•Pkd2wt/wt (control or wild-type) and MyH6•Pkd2flox/flox (mutant or Pkd2-KO) mice were used to study differential heart structure and function. Cardiac histology was used to study structure, and the “isolated working heart” system was adapted to mount and perfuse mouse heart to measure different cardiac parameters. We found that macrophage1 (M1) and macrophage 2 (M2) infiltration, transforming growth factor (TGF-b1) and TGF-b1 receptor expressions were significantly higher in Pkd2-KO, compared to wild-type hearts. The increase in the extracellular matrix in Pkd2-KO myocardium led to cardiac hypertrophy, interstitial and conduction system fibrosis, causing cardiac dysfunction with a predisposition to arrhythmia. Left ventricular (LV) expansion or compliance and LV filling were impaired in fibrotic Pkd2-KO hearts, resulted in diastolic dysfunction. LV systolic contractility and elastance decreased in fibrotic Pkd2-KO hearts, resulted in systolic dysfunction. Compared to wild-type hearts, Pkd2-KO hearts were less responsive to the pharmacological stress-test and changes in preload. In conclusion, Pkd2-KO mice had systolic and diastolic dysfunction with arrhythmogenic hearts

Heterogeneity and Plasticity of Human Breast Cancer Cells in Response to Molecularly-Targeted Drugs

Non-responsive subpopulation of tumor cells, and acquired resistance in initially responsive cells are major challenges for cancer therapy with molecularly-targeted drugs. While point mutations are considered the major contributing factor to acquired resistance, in this study we explored the role of heterogeneity and plasticity of selected human breast cancer cell lines (MDA-MB-231, MDA-MB-468, and AU565) in their initial and adjusted response, respectively, to ruxolitinib, everolimus, and erlotinib. After determination of lethal concentration for 50% cell death (LC50), cells were exposed to selected drugs using three different approaches: single exposure to 4 × LC50 and collection of surviving cells, multiple exposures to 1.5 × LC50 and monitoring the surviving population, and exposure to gradually increasing concentrations of selected drugs (range of concentrations equivalent to 10%of LC50 to 1.5 × LC50). Surviving cells were studied for adjustments in expression level of selected proteins using quantitative PCR and Western Blot. Our data indicated overexpression of a variety of proteins in resistant populations, which included cell membrane receptors EGFR and HER2, anti-apoptotic proteins Bcl-2 and BIRC8, and other proteins involved in cell signaling (e.g., Akt1, MAPK7, and RPS6KA5). Silencing the identified alternative proteins via siRNA resulted in significant drop in the LC50 of the selected molecularly-targeted drugs cells resistant to ruxolitinib (via targeting Akt), everolimus (via targeting EGFR, MAPK7, RPS6KA5, and HER2), and erlotinib (via silencing Bcl2 and BIRC8). Our data indicates that targeting well-selected alternative proteins could potentially sensitize the resistant cells to the effect of the molecularly-targeted treatment

Alzheimer’s Disease: Dawn of a New Era?

Alzheimer’s disease (AD) is an irreversible neurodegenerative disease characterized by a progressive decline in cognition and memory, leading to significant impairment in daily activities and ultimately death. It is the most common cause of dementia, the prevalence of which increases with age; however, age is not the only predisposing factor. The pathology of this cognitive impairing disease is still not completely understood, which has limited the development of valid therapeutic options. Recent years have witnessed a wide range of novel approaches to combat this disease, so that they greatly increased our understanding of the disease and of the unique drug development issues associated with this disease. In this paper, we provide a brief overview of the history, the clinical presentation and diagnosis, and we undertake a comprehensive review of the various approaches that have been brought to clinical trials in recent years, including immunotherapeutic approaches, tau-targeted strategies, neurotransmitter-based therapies, neurotropic and hematopoietic growth factors, and antioxidant therapies, trying to highlight the lessons learned from these approaches

Prostate Field Cancerization and Exosomes: Association Between CD9, Early Growth Response 1 and Fatty Acid Synthase

Intracapsular and well‑defined adenocarcinomas of the prostate are often surrounded by tissue areas that harbor molecular aberrations, including those of genetic, epigenetic and biochemical nature. This is known as field cancerization, or a field effect and denotes a state of pre‑malignancy. Such alterations in histologically normal tumor‑adjacent prostatic tissues have been recognized as clinically important and are potentially exploitable as biomarkers of disease and/or targets for preventative/therapeutic intervention. The authors have previously identified and validated two protein markers of field cancerization: The expressional upregulation of the transcription factor early growth response 1 (EGR‑1) and the lipogenic enzyme fatty acid synthase (FASN). However, the molecular etiology of prostate field cancerization, including EGR‑1 and FASN upregulation, remains largely unknown. It was thus hypothesized that extracellular vesicles, notably exosomes, released by tumor lesions may induce molecular alterations in the surrounding tissues, resulting in field cancerization, priming the tissue, and ultimately promoting multifocal tumorigenesis, which is often observed in prostate cancer. Towards testing this hypothesis, the current study, to the best of our knowledge, for the first time, presents correlative protein expression data, generated in disease‑free, tumor‑adjacent and cancerous human prostate tissues by quantitative immunofluorescence, between the exosomal marker CD9, and EGR‑1 and FASN. Despite the pilot character of the present study, and the static nature and heterogeneity of human tissues, the data suggest that CD9 expression itself is part of a field effect. In support of this hypothesis, the results suggest a possible contribution of exosomes to the induction of field cancerization in the prostate, particularly for EGR‑1. These findings were corroborated in established cell models of cancerous (LNCaP) and non‑cancerous (RWPE‑1) human prostate epithelial cells. The findings of this study warrant further investigation into the functional interface between exosomes and field cancerization, as a detailed understanding of this characterization may lead to the development of clinical applications related to diagnosis and/or prognosis and targeted intervention to prevent progression from pre‑malignancy to cancer

Amphiphilic Peptides for Efficient siRNA Delivery

A number of amphiphilic cyclic peptides—[FR]4, [WR]5, and [WK]5—containing hydrophobic and positively-charged amino acids were synthesized by Fmoc/tBu solid-phase peptide methods and evaluated for their efficiency in intracellular delivery of siRNA to triple-negative breast cancer cell lines, MDA-MB-231 and MDA-MB-468, in the presence and absence of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). Among the peptides, [WR]5, which contains alternate tryptophan (W) and arginine (R) residues, was found to be the most efficient in the delivery of siRNA by improving the delivery by more than 3-fold when compared to other synthesized cyclic peptides that were not efficient. The data also showed that co-formulation of [WR]5 with lipid DOPE significantly enhanced the efficiency of siRNA delivery by up to ~2-fold compared to peptide alone. Based on the data indicating the efficiency of [WR]5 in siRNA delivery, peptides containing arginine residues on the ring and tryptophan residues on the side chain, [R6K]W6 and [R5K]W5, were also evaluated, and demonstrated improved delivery of siRNA. The presence of DOPE again enhanced the siRNA delivery in most cases. [WR]5, [R5K]W5, and [R6K]W6 did not show any significant toxicity in MDA-MB-231, MDA-MB-468, and AU565 WT cells at N/P ratios of 20:1 or less, in the presence and absence of DOPE. Silencing of kinesin spindle protein (KSP) and Janus kinase 2 (JAK2) was evaluated in MDA-MB-231 cells in the presence of the peptides. The addition of DOPE significantly enhanced the silencing efficiency for all selected peptides. In conclusion, peptides containing typtophan and arginine residues were found to enhance siRNA delivery and to generate silencing of targeted proteins in the presence of DOPE

Untargeted Metabolomics Analysis on Kidney Tissues from Mice Reveals Potential Hypoxia Biomarkers

Chronic hypoxia may have a huge impact on the cardiovascular and renal systems. Advancements in microscopy, metabolomics, and bioinformatics provide opportunities to identify new biomarkers. In this study, we aimed at elucidating the metabolic alterations in kidney tissues induced by chronic hypoxia using untargeted metabolomic analyses. Reverse phase ultrahigh performance liquid chromatography-mass spectroscopy/mass spectroscopy (RP–UPLC–MS/MS) and hydrophilic interaction liquid chromatography (HILIC)–UPLC–MS/MS methods with positive and negative ion mode electrospray ionization were used for metabolic profiling. The metabolomic profiling revealed an increase in metabolites related to carnitine synthesis and purine metabolism. Additionally, there was a notable increase in bilirubin. Heme, N-acetyl-L-aspartic acid, thyroxine, and 3-beta-Hydroxy-5-cholestenoate were found to be significantly downregulated. 3-beta-Hydroxy-5-cholestenoate was downregulated more significantly in male than female kidneys. Trichome Staining also showed remarkable kidney fibrosis in mice subjected to chronic hypoxia. Our study offers potential intracellular metabolite signatures for hypoxic kidneys

Subtype-Selective Positive Modulation of K\u3csub\u3eCa\u3c/sub\u3e2.3 Channels Increases Cilia Length

Small-conductance Ca2+-activated potassium (KCa2.x) channels are gated exclusively by intracellular Ca2+. The activation of KCa2.3 channels induces hyperpolarization, which augments Ca2+ signaling in endothelial cells. Cilia are specialized Ca2+ signaling compartments. Here, we identified compound 4 that potentiates human KCa2.3 channels selectively. The subtype selectivity of compound 4 for human KCa2.3 over rat KCa2.2a channels relies on an isoleucine residue in the HA/HB helices. Positive modulation of KCa2.3 channels by compound 4 increased flow-induced Ca2+ signaling and cilia length, while negative modulation by AP14145 reduced flow-induced Ca2+ signaling and cilia length. These findings were corroborated by the increased cilia length due to the expression of Ca2+-hypersensitive KCa2.3_G351D mutant channels and the reduced cilia length resulting from the expression of Ca2+-hyposensitive KCa2.3_I438N channels. Collectively, we were able to associate functions of KCa2.3 channels and cilia, two crucial components in the flow-induced Ca2+ signaling of endothelial cells, with potential implications in vasodilation and ciliopathic hypertension