Expression and inducibility of cytochrome P450s (CYP1A1, 2B6, 2E1, 3A4) in human cord blood CD34(+) stem cell-derived differentiating neuronal cells

Relationship between blood-brain barrier changes and drug metabolism under high-altitude hypoxia: obstacle or opportunity for drug transport?

The blood-brain barrier is essential for maintaining the stability of the central nervous system and is also crucial for regulating drug metabolism, changes of blood-brain barrier's structure and function can influence how drugs are delivered to the brain. In high-altitude hypoxia, the central nervous system's function is drastically altered, which can cause disease and modify the metabolism of drugs in vivo. Changes in the structure and function of the blood-brain barrier and the transport of the drug across the blood-brain barrier under high-altitude hypoxia, are regulated by changes in brain microvascular endothelial cells, astrocytes, and pericytes, either regulated by drug metabolism factors such as drug transporters and drug-metabolizing enzymes. This article aims to review the effects of high-altitude hypoxia on the structure and function of the blood-brain barrier as well as the effects of changes in the blood-brain barrier on drug metabolism. We also hypothesized and explore the regulation and potential mechanisms of the blood-brain barrier and associated pathways, such as transcription factors, inflammatory factors, and nuclear receptors, in regulating drug transport under high-altitude hypoxia.

Metabolic conjugation reduces in vitro toxicity of the flavonoid nevadensin

The present study focuses on the association between metabolic capacity and toxicity of the natural occurring flavonoid nevadensin in vitro. Human colon (HT29), liver (HepG2) and bone marrow (KG1) carcinoma cells were used and strong cell line dependent differences in toxic effect strength were found. HepG2 and KG1 cells were more sensitive against nevadensin treatment in comparison to HT29 cells. High resolution mass spectrometry experiments showed that nevadensin is rapidly glucuronidated in HT29 cells, whereas KG1 cells do not metabolize nevadensin, thus glucuronidation was supposed to be a crucial metabolic pathway in vitro. To proof this suggestion, nevadensin glucuronides were isolated from pig liver microsomes und structurally elucidated via NMR spectroscopy. In HepG2 cells a cellular enrichment of nevadensin itself as well as nevadensin-7-O-glucuronide was determined by tandem mass spectrometry. A proteomic screening of uridine 5'-diphospho (UDP)-glucuronosyltransferase (UGT) in HT29 and HepG2 cells provided first hints that the isoforms UGT1A6 and UGT1A1 are responsible for nevadensin glucuronidation. Additionally, nevadensin was found to be a potent SULT inhibitor in HepG2 cells. In sum, the present study clearly illustrates the importance of obtaining detailed information about metabolic competence of cell lines which should be considered in the evaluation of toxic endpoints.

The Implementation of the Three Rs in Regulatory Toxicity and Biosafety Assessment: The Indian Perspective

Animal models have long served as a basis for scientific experimentation, biomedical research, drug development and testing, disease modelling and toxicity studies, as they are widely thought to provide meaningful, human-relevant predictions. However, many of these systems are resource intensive and time-consuming, have low predictive value and are associated with great social and ethical dilemmas. Often drugs appear to be effective and safe in these classical animal models, but later prove to be ineffective and/or unsafe in clinical trials. These issues have paved the way for a paradigm shift from the use of in vivo approaches, toward the 'science of alternatives'. This has fuelled several research and regulatory initiatives, including the ban on the testing of cosmetics on animals. The new paradigm has been shifted toward increasing the relevance of the models for human predictivity and translational efficacy, and this has resulted in the recent development of many new methodologies, from 3-D bio-organoids to bioengineered 'human-on-a-chip' models. These improvements have the potential to significantly advance medical research globally. This paper offers a stance on the existing strategies and practices that utilise alternatives to animals, and outlines progress on the incorporation of these models into basic and applied research and education, specifically in India. It also seeks to provide a strategic roadmap to streamline the future directions for the country's policy changes and investments. This strategic roadmap could be a useful resource to guide research institutions, industries, regulatory agencies, contract research organisations and other stakeholders in transitioning toward modern approaches to safety and risk assessment that could replace or reduce the use of animals without compromising the safety of humans or the environment.

Cytochrome P450 expression and regulation in the brain

The regulation of brain cytochrome P450 enzymes (CYPs) is different compared with respective hepatic enzymes. This may result from anatomical bases and physiological functions of the two organs. The brain is composed of a variety of functional structures built of different interconnected cell types endowed with specific receptors that receive various neuronal signals from other brain regions. Those signals activate transcription factors or alter functioning of enzyme proteins. Moreover, the blood-brain barrier (BBB) does not allow free penetration of all substances from the periphery into the brain. Differences in neurotransmitter signaling, availability to endogenous and exogenous active substances, and levels of transcription factors between neuronal and hepatic cells lead to differentiated expression and susceptibility to the regulation of CYP genes in the brain and liver. Herein, we briefly describe the CYP enzymes of CYP1-3 families, their distribution in the brain, and discuss brain-specific regulation of CYP genes. In parallel, a comparison to liver CYP regulation is presented. CYP enzymes play an essential role in maintaining the levels of bioactive molecules within normal ranges. These enzymes modulate the metabolism of endogenous neurochemicals, such as neurosteroids, dopamine, serotonin, melatonin, anandamide, and exogenous substances, including psychotropics, drugs of abuse, neurotoxins, and carcinogens. The role of these enzymes is not restricted to xenobiotic-induced neurotoxicity, but they are also involved in brain physiology. Therefore, it is crucial to recognize the function and regulation of CYP enzymes in the brain to build a foundation for future medicine and neuroprotection and for personalized treatment of brain diseases.

The constitutive androstane receptor and pregnane X receptor in the brain

Since their discovery, the orphan nuclear receptors constitutive androstane receptor (CAR;NR1I3) and pregnane X receptor (PXR;NR1I2) have been regarded as master regulators of drug disposition and detoxification mechanisms. They regulate the metabolism and transport of endogenous mediators and xenobiotics in organs including the liver, intestine and brain. However, with proposals of new physiological functions for NR1I3 and NR1I2, there is increasing interest in the role of these receptors in influencing brain function. This review will summarise key findings regarding the expression and function of NR1I3 and NR1I2 in the brain, hereby highlighting the need for further research in this field.

Cord blood research, banking, and transplantation: achievements, challenges, and perspectives

The first hematopoietic transplant in which umbilical cord blood (UCB) was used as the source of hematopoietic cells was performed in October 1988. Since then, significant achievements have been reported in terms of our understanding of the biology of UCB-derived hematopoietic stem (HSCs) and progenitor (HPCs) cells. Over 40,000 UCB transplants (UCBTs) have been performed, in both children and adults, for the treatment of many different diseases, including hematologic, metabolic, immunologic, neoplastic, and neurologic disorders. In addition, cord blood banking has been developed to the point that around 800,000 units are being stored in public banks and more than 4 million units in private banks worldwide. During these 30 years, research in the UCB field has transformed the hematopoietic transplantation arena. Today, scientific and clinical teams are still working on different ways to improve and expand the use of UCB cells. A major effort has been focused on enhancing engraftment to potentially reduce risk of infection and cost. To that end, we have to understand in detail the molecular mechanisms controlling stem cell self-renewal that may lead to the development of ex vivo systems for HSCs expansion, characterize the mechanisms regulating the homing of HSCs and HPCs, and determine the relative place of UCBTs, as compared to other sources. These challenges will be met by encouraging innovative research on the basic biology of HSCs and HPCs, developing novel clinical trials, and improving UCB banking both in the public and private arenas.

Regulation of brain drug metabolizing enzymes and transporters by nuclear receptors

Nuclear receptors (NRs) belong to a family of ligand-dependent transcription factors. The target genes of NRs include many drug metabolizing enzymes and transporters. The central nervous system (CNS) bears the expression of NRs, drug metabolizing enzymes and transporters. NRs that express in the brain can be divided into three groups according to their characteristics of ligand binding: steroid hormone receptors, non-steroid hormone receptors, and orphan receptors. The NR-mediated regulation of drug metabolizing enzymes and transporters plays important roles in the metabolism and disposition of drugs in the CNS and the penetration of endogenous and exogenous substances through the blood-brain barrier (BBB). NR-mediated regulation of drug metabolizing enzymes and transporters can cause the toxicological effects of xenobiotics in the CNS and also lead to drug resistance in the centrum. The regulatory pathways of drug metabolizing enzymes and transporters can provide new strategies for selective regulation of the BBB permeability and drug metabolism in the brain. This review focuses on the importance of NR-mediated regulation of drug metabolizing enzymes and transporters in the CNS and the implications of this regulation in the therapeutic effect of CNS drugs and CNS side effects of drugs and other xenotoxicants.

Effects of fine air particulates on gene expression in non-small-cell lung cancer

PURPOSE

Airborne particulate matter smaller than 2.5μm (PM_2.5) has been shown to induce adverse health effects through various mechanisms. However, its effects on gene expression in non-small-cell lung cancer (NSCLC) remain undefined. The aim of this study was to analyze the expression profile of PM_2.5-induced adverse health effects on human.

MATERIALS AND METHODS

We performed RNA sequencing to elucidate key molecular effects of PM_2.5 collected from Shenyang China, to identify potential diagnostic markers or therapeutic targets, and further validated these differences in gene expression by using quantitative PCR in A549 and H1299 human non-small-cell lung cancer cell lines. To investigate the functional changes on PM_2.5 exposed cells, we carried out the viability assay for the cell counting, and the Boyden chamber assay for invasion.

RESULTS

We found 143 genes that were expressed at least twice as much, or no more than half as much, in NSCLC cells exposed to PM_2.5 than in unexposed cells. Results showed deregulated genes confronted PM_2.5 exposure were significantly expressed, but commonly expressed in NSCLC cells. In addition, according to the viability assay and the Boyden chamber assay, PM_2.5 exposed cells which have more competent on proliferation and invasion can keep the line with the results in RNA-Seq.

CONCLUSION

Our data may provide a more specific understanding of the signaling patterns associated with pathogenesis, and lead to novel markers and therapeutic targets for NSCLC.

Autophagy Activation Alleviates Amyloid-β-Induced Oxidative Stress, Apoptosis and Neurotoxicity in Human Neuroblastoma SH-SY5Y Cells

Autophagy is an evolutionary conserved catabolic process that ensures continuous removal of damaged cell organelles and long-lived protein aggregates to maintain cellular homeostasis. Although autophagy has been implicated in amyloid-β (Aβ) production and deposition, its role in pathogenesis of Alzheimer's disease remains elusive. Thus, the present study was undertaken to assess the cytoprotective and neuroprotective potential of autophagy on Aβ-induced oxidative stress, apoptosis and neurotoxicity in human neuroblastoma SH-SY5Y cells. The treatment of Aβ1-42 impaired the cell growth and redox balance, and induced apoptosis and neurotoxicity in SH-SY5Y cells. Next, the treatment of rapamycin (RAP) significantly elevated the expression of autophagy markers such as microtubule-associated protein-1 light chain-3 (LC3), sequestosome-1/p62, Beclin-1, and unc-51-like kinase-1 (ULK1) in SH-SY5Y cells. RAP-induced activation of autophagy notably alleviated the Aβ1-42-induced impairment of redox balance by decreasing the levels of pro-oxidants such as reactive oxygen species, lipid peroxidation and Ca²⁺ influx, and concurrently increasing the levels of antioxidant enzymes such as superoxide dismutase and catalase. The RAP-induced autophagy also ameliorated Aβ1-42-induced loss of mitochondrial membrane potential and apoptosis. Additionally, the activated autophagy provided significant neuroprotection against Aβ1-42-induced neurotoxicity by elevating the expression of neuronal markers such as synapsin-I, PSD95, NCAM, and CREB. However, 3-methyladenine treatment significantly exacerbated the neurotoxic effects of Aβ1-42. Taken together, our study demonstrated that the activation of autophagy provided possible neuroprotection against Aβ-induced cytotoxicity, oxidative stress, apoptosis, and neurotoxicity in SH-SY5Y neuronal cells.

Monocrotophos Induces the Expression of Xenobiotic Metabolizing Cytochrome P450s (CYP2C8 and CYP3A4) and Neurotoxicity in Human Brain Cells

Expression of various cytochrome P450s (CYPs) in mammalian brain cells is well documented. However, such studies are hampered in neural/glial cells of human origin due to nonavailability of human brain cells. To address this issue, we investigated the expression and inducibility of CYP2C8 and CYP3A4 and their responsiveness against cyclophosphamide (CPA) and organophosphorus pesticide monocrotophos (MCP), a known developmental neurotoxicant in human neural (SH-SY5Y) and glial (U373-MG) cell lines. CPA induced significant expression of CYP2C8 and CYP3A4 in both types of cells in a time-dependent manner. Neural cell line exhibited relatively higher constitutive and inducible expression of CYPs than the glial cell line. MCP exposure alone could not induce the significant expression of CYPs, whereas the cells preexposed to CPA showed a significant response to MCP. Similar to the case of CPA induced expressions, neural cells were found to be more vulnerable than glial cells. Our data indicate differential expressions of CYPs in cultured human neural and glial cell lines. The findings were synchronized with protein ligand docking studies, which showed a significant modulatory capacity of MCP by strong interaction with CYP regulators-CAR and PXR. Similarly, the known CYP inducer CPA has also shown significant high docking scores with the two studied CYP regulators. We also observed a significant induction in reactive oxygen species (ROS), lipid peroxides (LPO), micronucleus (MN), chromosomal aberration (CA), and reduction in reduced glutathione (GSH) and catalase following the exposure of MCP. Moreover, the expressions of apoptotic markers such as caspase-3, caspase-9, Bax, and p53 were significantly upregulated, whereas the levels of antiapoptotic marker, Bcl2, was downregulated after the exposure of MCP in both cell lines. These findings confirm the involvement of ROS-mediated oxidative stress, which subsequently triggers apoptosis pathways in both human neural (SH-SY5Y) and glial (U373-MG) cell lines following the exposure of MCP.

RXRα, PXR and CAR xenobiotic receptors mediate the apoptotic and neurotoxic actions of nonylphenol in mouse hippocampal cells

In the present study, we investigated the role of the retinoid X receptor (RXR), the pregnane X receptor (PXR) and the constitutive androstane receptor (CAR), in the apoptotic and toxic effects of nonylphenol in mouse primary neuronal cell cultures. Our study demonstrated that nonylphenol activated caspase-3 and induced lactate dehydrogenase (LDH) release in hippocampal cells, which was accompanied by an increase in the mRNA expression and protein levels of RXRα, PXR and CAR. Nonylphenol stimulated Rxra, Pxr, and Car mRNA expression. These effects were followed by increase in the protein levels of particular receptors. Immunofluorescence labeling revealed the cellular distribution of RXRα, PXR and CAR in hippocampal neurons in response to nonylphenol, shortening of neurites and cytoplasmic shrinking, as indicated by MAP2 staining. It also showed NP-induced translocation of receptor-specific immunofluorescence from cytoplasm to the nucleus. The use of specific siRNAs demonstrated that Rxra-, Pxr-, and Car-siRNA-transfected cells were less vulnerable to nonylphenol-induced activation of caspase-3 and LDH, thus confirming the key involvement of RXRα/PXR/CAR signaling pathways in the apoptotic and neurotoxic actions of nonylphenol. These new data give prospects for the targeting xenobiotic nuclear receptors to protect the developing nervous system against endocrine disrupting chemicals.

An Overview on Human Umbilical Cord Blood Stem Cell-Based Alternative In Vitro Models for Developmental Neurotoxicity Assessment

The developing brain is found highly vulnerable towards the exposure of different environmental chemicals/drugs, even at concentrations, those are generally considered safe in mature brain. The brain development is a very complex phenomenon which involves several processes running in parallel such as cell proliferation, migration, differentiation, maturation and synaptogenesis. If any step of these cellular processes hampered due to exposure of any xenobiotic/drug, there is almost no chance of recovery which could finally result in a life-long disability. Therefore, the developmental neurotoxicity (DNT) assessment of newly discovered drugs/molecules is a very serious concern among the neurologists. Animal-based DNT models have their own limitations such as ethical concerns and lower sensitivity with less predictive values in humans. Furthermore, non-availability of human foetal brain tissues/cells makes job more difficult to understand about mechanisms involve in DNT in human beings. Although, the use of cell culture have been proven as a powerful tool for DNT assessment, but many in vitro models are currently utilizing genetically unstable cell lines. The interpretation of data generated using such terminally differentiated cells is hard to extrapolate with in vivo situations. However, human umbilical cord blood stem cells (hUCBSCs) have been proposed as an excellent tool for alternative DNT testing because neuronal development from undifferentiated state could exactly mimic the original pattern of neuronal development in foetus when hUCBSCs differentiated into neuronal cells. Additionally, less ethical concern, easy availability and high plasticity make them an attractive source for establishing in vitro model of DNT assessment. In this review, we are focusing towards recent advancements on hUCBSCs-based in vitro model to understand DNTs.

Preferential expression of cytochrome CYP CYP2R1 but not CYP1B1 in human cord blood hematopoietic stem and progenitor cells

Cytochrome P450 (CYP) enzymes metabolize numerous endogenous substrates, such as retinoids, androgens, estrogens and vitamin D, that can modulate important cellular processes, including proliferation, differentiation and apoptosis. The aim of this study is to characterize the expression of CYP genes in CD34+ human cord blood hematopoietic stem and early progenitor cells (CBHSPCs) as a first step toward assessment of the potential biological functions of CYP enzymes in regulating the expansion or differentiation of these cells. CD34+ CBHSPCs were purified from umbilical cord blood via antibody affinity chromatography. Purity of CD34+ CBHSPCs was assessed using fluorescence-activated cell sorting. RNA was isolated from purified CD34+ CBHSPCs and total mononuclear cells (MNCs) for RNA-PCR analysis of CYP expression. Fourteen human CYPs were detected in the initial screening with qualitative RT-PCR in CD34+ CBHSPCs. Further quantitative RNA-PCR analysis of the detected CYP transcripts yielded evidence for preferential expression of CYP2R1 in CD34+ CBHSPCs relative to MNCs; and for greater expression of CYP1B1 in MNCs relative to CD34+ CBHSPCs. These findings provide the basis for further studies on possible functions of CYP2R1 and CYP1B1 in CBHSPCs׳ proliferation and/or differentiation and their potential utility as targets for drugs designed to modulate CD34+ CBHSPC expansion or differentiation.

Monocrotophos induces the expression and activity of xenobiotic metabolizing enzymes in pre-sensitized cultured human brain cells

The expression and metabolic profile of cytochrome P450s (CYPs) is largely missing in human brain due to non-availability of brain tissue. We attempted to address the issue by using human brain neuronal (SH-SY5Y) and glial (U373-MG) cells. The expression and activity of CYP1A1, 2B6 and 2E1 were carried out in the cells exposed to CYP inducers viz., 3-methylcholanthrene (3-MC), cyclophosphamide (CPA), ethanol and known neurotoxicant- monocrotophos (MCP), a widely used organophosphorous pesticide. Both the cells show significant induction in the expression and CYP-specific activity against classical inducers and MCP. The induction level of CYPs was comparatively lower in MCP exposed cells than cells exposed to classical inducers. Pre-exposure (12 h) of cells to classical inducers significantly added the MCP induced CYPs expression and activity. The findings were concurrent with protein ligand docking studies, which show a significant modulatory capacity of MCP by strong interaction with CYP regulators-CAR, PXR and AHR. Similarly, the known CYP inducers- 3-MC, CPA and ethanol have also shown significantly high docking scores with all the three studied CYP regulators. The expression of CYPs in neuronal and glial cells has suggested their possible association with the endogenous physiology of the brain. The findings also suggest the xenobiotic metabolizing capabilities of these cells against MCP, if received a pre-sensitization to trigger the xenobiotic metabolizing machinery. MCP induced CYP-specific activity in neuronal cells could help in explaining its effect on neurotransmission, as these CYPs are known to involve in the synthesis/transport of the neurotransmitters. The induction of CYPs in glial cells is also of significance as these cells are thought to be involved in protecting the neurons from environmental insults and safeguard them from toxicity. The data provide better understanding of the metabolizing capability of the human brain cells against xenobiotics.

Substrate-dependent gene regulation of self-assembled human MSC spheroids on chitosan membranes

Background

Three-dimensional (3D) multicellular spheroids of mesenchymal stem cells (MSCs) are generally regarded to have beneficial properties over MSCs in monolayer. Recent literatures have documented that MSCs can self-assemble into 3D spheroids with a greater capacity for differentiation into various cell types when grown on chitosan (CS), a biopolymer. The genomic modulation occurring in these MSC spheroids is thus of essential importance for understanding their uniqueness and therapeutic potentials. In this study, 3D spheroids self-assembled from human umbilical cord MSCs grown on CS membranes were analyzed by mRNA as well as microRNA microarrays, which helped identify the critical signaling events that may alter the cellular functions during the spheroid forming process.

Results

Genes screened from mRNA and microRNA cross-correlation analyses were further confirmed with the quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) analysis. Results revealed the regulation of a significant number of calcium-associated genes, which suggested the crucial role of calcium signaling in CS-derived MSC spheroids. In addition, many genes associated with the multilineage differentiation capacities and those associated with the antiinflammatory and antitumor properties of MSCs were upregulated. The genetic modulation was significantly more remarkable and endured longer for MSC spheroids derived on CS substrates compared to those derived on a non-adherent (polyvinyl alcohol) substrate.

Conclusions

Based on the study, the culture substrates used to prepare 3D MSC spheroids may predefine their properties through cell-substrate interaction.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-10) contains supplementary material, which is available to authorized users.

Concise review: ex vivo expansion of cord blood-derived hematopoietic stem and progenitor cells: basic principles, experimental approaches, and impact in regenerative medicine

Hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) play key roles in the production of mature blood cells and in the biology and clinical outcomes of hematopoietic transplants. The numbers of these cells, however, are extremely low, particularly in umbilical cord blood (UCB); thus, ex vivo expansion of human UCB-derived HSCs and HPCs has become a priority in the biomedical field. Expansion of progenitor cells can be achieved by culturing such cells in the presence of different combinations of recombinant stimulatory cytokines; in contrast, expansion of actual HSCs has proved to be more difficult because, in addition to needing recombinant cytokines, HSCs seem to deeply depend on the presence of stromal cells and/or elements that promote the activation of particular self-renewal signaling pathways. Hence, there is still controversy regarding the optimal culture conditions that should be used to achieve this. To date, UCB transplants using ex vivo-expanded cells have already been performed for the treatment of different hematological disorders, and although results are still far from being optimal, the advances are encouraging. Recent studies suggest that HSCs may also give rise to nonhematopoietic cells, such as neural, cardiac, mesenchymal, and muscle cells. Such plasticity and the possibility of producing nonhematopoietic cells at the clinical scale could bring new alternatives for the treatment of neural, metabolic, orthopedic, cardiac, and neoplastic disorders. Once standardized, ex vivo expansion of human HSCs/HPCs will surely have a positive impact in regenerative medicine.

Trans-resveratrol restores the damages induced by organophosphate pesticide-monocrotophos in neuronal cells

The restorative potential of trans-resveratrol (RV) was investigated in a rat neuronal cell line (PC12) exposed to organophosphate pesticide-monocrotophos (MCP). RV shows significant protection against MCP-induced alterations in PC12 cells by restoration of oxidative stress-mediated apoptosis and cytotoxicity. RV treatment significantly reduced reactive oxygen species (ROS) production and lipid peroxidation, and also restored glutathione levels and mitochondrial membrane potential, in cells receiving MCP. Restoration of markers such as cytochrome c, Bax, Bcl-2 and caspase-3 also confirms the effectiveness of RV against MCP-induced, mitochondria-mediated apoptosis in PC12 cells. The data identify the protective/restorative potential of RV against MCP-induced neuronal damages by affecting ROS production and the level of antioxidant defence enzymes.