H4 Cells Research Articles

A miniaturized hydrogel-based in vitro model for dynamic culturing of human cells overexpressing beta-amyloid precursor protein

Recent findings have highlighted an interconnection between intestinal microbiota and the brain, referred to as microbiota–gut–brain axis, and suggested that alterations in microbiota composition might affect brain functioning, also in Alzheimer’s disease. To investigate microbiota–gut–brain axis biochemical pathways, in this work we developed an innovative device to be used as modular unit in an engineered multi-organ-on-a-chip platform recapitulating in vitro the main players of the microbiota–gut–brain axis, and an innovative three-dimensional model of brain cells based on collagen/hyaluronic acid or collagen/poly(ethylene glycol) semi-interpenetrating polymer networks and β-amyloid precursor protein-Swedish mutant-expressing H4 cells, to simulate the pathological scenario of Alzheimer’s disease. We set up the culturing conditions, assessed cell response, scaled down the three-dimensional models to be hosted in the organ-on-a-chip device, and cultured them both in static and in dynamic conditions. The results suggest that the device and three-dimensional models are exploitable for advanced engineered models representing brain features also in Alzheimer’s disease scenario.

Negative regulation of autophagy by UBA6-BIRC6-mediated ubiquitination of LC3.

Although the process of autophagy has been extensively studied, the mechanisms that regulate it remain insufficiently understood. To identify novel autophagy regulators, we performed a whole-genome CRISPR/Cas9 knockout screen in H4 human neuroglioma cells expressing endogenous LC3B tagged with a tandem of GFP and mCherry. Using this methodology, we identified the ubiquitin-activating enzyme UBA6 and the hybrid ubiquitin-conjugating enzyme/ubiquitin ligase BIRC6 as autophagy regulators. We found that these enzymes cooperate to monoubiquitinate LC3B, targeting it for proteasomal degradation. Knockout of UBA6 or BIRC6 increased autophagic flux under conditions of nutrient deprivation or protein synthesis inhibition. Moreover, UBA6 or BIRC6 depletion decreased the formation of aggresome-like induced structures in H4 cells, and α-synuclein aggregates in rat hippocampal neurons. These findings demonstrate that UBA6 and BIRC6 negatively regulate autophagy by limiting the availability of LC3B. Inhibition of UBA6/BIRC6 could be used to enhance autophagic clearance of protein aggregates in neurodegenerative disorders.

Mechanical Compression Regulates Brain Cancer Cell Migration Through MEK1/Erk1 Pathway Activation and GDF15 Expression

Mechanical compression is a common abnormality of brain tumors that has been shown to be responsible for the severe neurological defects of brain cancer patients representing a negative prognostic factor. Indeed, it is of note that patients that undergo resection exhibited higher survival rates than those subjected to biopsy only, suggesting that compressive forces generated during brain tumor growth play a key role in tumor progression. Despite the importance of mechanical compression in brain tumors, there is a lack of studies examining its direct effects on brain cancer cells and the mechanisms involved. In the present study, we used two brain cancer cell lines with distinct metastatic potential, the less aggressive H4 and the highly aggressive A172 cell lines, in order to study the effect of compression on their proliferative and migratory ability. Specifically, we used multicellular tumor spheroids (MCS) embedded in agarose matrix to show that compression strongly impaired their growth. Using mathematical modeling, we estimated the levels of compressive stress generated during the growth of brain MCS and then we applied the respective stress levels on brain cancer cell monolayers using our previously established transmembrane pressure device. By performing a scratch assay, we found that compression strongly induced the migration of the less aggressive H4 cells, while a less pronounced effect was observed for A172 cells. Analysis of the gene expression profile of both cell lines revealed that GDF15 and small GTPases are strongly regulated by mechanical compression, while GDF15 was further shown to be necessary for cells to migrate under compression. Through a phospho-proteomic screening, we further found that compressive stimulus is transmitted through the MEK1/Erk1 signaling pathway, which is also necessary for the migration of brain cancer cells. Finally, our results gave the first indication that GDF15 could regulate and being regulated by MEK1/Erk1 signaling pathway in order to facilitate the compression-induced brain cancer cell migration, rendering them along with small GTPases as potential targets for future anti-metastatic therapeutic innovations to treat brain tumors.

Induction of Urokinase Activity by Retinoic Acid in Two Cell Lines of Neuronal Origin.

Retinoic acid is one of the most well-known agents able to induce differentiation in several types of tumours. Unfortunately, most of the tumours are refractive to the differentiation cues. The aim of this investigation was to analyse the effects of prolonged treatment with retinoic acid on two cell lines of neural origin refractive to differentiation. Cells were also treated with retinoic acid in combination with a poly(ADP-ribosyl) polymerase (PARP) inhibitor because PARP1 is a known chromatin modulator and can influence the process of differentiation. The main methods comprised tumour cell line culturing and treatment; analysis of RNA and protein expression after cell treatment; as well as analysis of urokinase activity, migration, and proliferation. Both cell lines continued to proliferate under the prolonged treatment and showed increase in urokinase plasminogen activator activity. Analysis of gene expression and cell phenotype revealed different mechanisms, which only in neuroblastoma H4 cells could indicate the process of epithelial-mesenchymal transition. The data collected indicate that the activity of the urokinase plasminogen activator, although belonging to an extracellular protease, does not necessary lead to epithelial-mesenchymal reprogramming and increase in cell migration but can have different outcomes depending on the intracellular milieu.

ALWPs Improve Cognitive Function and Regulate Aβ Plaque and Tau Hyperphosphorylation in a Mouse Model of Alzheimer's Disease.

Recently, we reported that ALWPs, which we developed by combining Liuwei Dihuang pills (LWPs) with antler, regulate the LPS-induced neuroinflammatory response and rescue LPS-induced short- and long-term memory impairment in wild-type (WT) mice. In the present study, we examined the effects of ALWPs on Alzheimer’s disease (AD) pathology and cognitive function in WT mice as well as 5x FAD mice (a mouse model of AD). We found that administration of ALWPs significantly reduced amyloid plaque levels in 5x FAD mice and significantly decreased amyloid β (Aβ) levels in amyloid precursor protein (APP)-overexpressing H4 cells. In addition, ALWPs administration significantly suppressed tau hyperphosphorylation in 5x FAD mice. Oral administration of ALWPs significantly improved long-term memory in scopolamine (SCO)-injected WT mice and 5x FAD mice by altering dendritic spine density. Importantly, ALWPs promoted spinogenesis in primary hippocampal neurons and WT mice and modulated the dendritic spine number in an extracellular signal-regulated kinase (ERK)-dependent manner. Taken together, our results suggest that ALWPs are a candidate therapeutic drug for AD that can modulate amyloid plaque load, tau phosphorylation, and synaptic/cognitive function.

Coordinated Expression of Ras Suppressor 1 (RSU-1) and Growth Differentiation Factor 15 (GDF15) Affects Glioma Cell Invasion.

Glioblastoma multiforme (GBM) is the most aggressive type of brain tumor due to its invasive phenotype. Ras suppressor 1 (RSU-1) is a cell-extracellular matrix adhesion protein and we recently found that it promotes cell invasion in aggressive cells and inhibits it in non-invasive. Growth differentiation factor-15 (GDF15) is known to be involved in actin cytoskeleton reorganization and metastasis. In this study, we used three brain cell lines (H4, SW1088 and A172) with increasing RSU-1 expression levels and invasive capacity and decreasing GDF15 levels to investigate the interplay between RSU-1 and GDF15 with regard to cell invasion. Four experimental approaches were used: (a) GDF15 treatment, (b) Rsu-1 silencing, (c) GDF15 silencing, and (d) combined GDF15 treatment and RSU-1 silencing. We found that the differential expression of RSU-1 and GDF15 in H4 and A172 cells leading to inhibition of cell invasion in H4 cells and promotion in A172 through respective changes in PINCH1, RhoA and MMP-13 expression. Interestingly SW1088, with intermediate RSU-1 and GDF15 expression, were not affected by any treatment. We conclude that there is a strong connection between RSU-1 and GDF15 in H4, SW1088 and A172 cells and the relative expression of these two proteins is fundamental in affecting their invasive fate.

The developmentally regulated fetal enterocyte gene, ZP4, mediates anti-inflammation by the symbiotic bacterial surface factor polysaccharide A on Bacteroides fragilis.

Initial colonizing bacteria play a critical role in completing the development of the immune system in the gastrointestinal tract of infants. Yet, the interaction of colonizing bacterial organisms with the developing human intestine favors inflammation over immune homeostasis. This characteristic of bacterial-intestinal interaction partially contributes to the pathogenesis of necrotizing enterocolitis (NEC), a devastating premature infant intestinal inflammatory disease. However, paradoxically some unique pioneer bacteria (initial colonizing species) have been shown to have a beneficial effect on the homeostasis of the immature intestine and the prevention of inflammation. We have reported that one such pioneer bacterium, Bacteroides fragilis (B. fragilis), and its surface component polysaccharide A (PSA) inhibit IL-1β-induced inflammation in a human primary fetal small intestinal cell line (H4 cells). In this study, using transcription profiling of H4 cellular RNA after pretreatment with or without PSA before an inflammatory stimulation of IL-1β, we have begun to further determine the cellular mechanism for anti-inflammation. We show that a developmentally regulated gene, zona pellucida protein 4 (ZP4), is uniquely elevated after IL-1β stimulation and reduced with PSA exposure. ZP4 was known as a sperm receptor-mediating species-specific binding protein in the initial life of mammals. However, its intestinal epithelial function is unclear. We found that ZP4 is a developmentally regulated gene involved with immune function and regulated by both Toll-like receptor 2 and 4. Knockdown of ZP4-affected PSA inhibited IL-8 mRNA expression in response to IL-1β. This represents an initial study of ZP4 innate immune function in immature enterocytes. This study may lead to new opportunity for efficient treatment of NEC.NEW & NOTEWORTHY This study extends previous observations to define the cellular mechanisms of polysaccharide A-induced anti-inflammation in immature enterocytes using transcription profiling of enterocyte genes after preexposure to polysaccharide A before an inflammatory stimulus with IL-1β.

Iron-mediated aggregation and toxicity in a novel neuronal cell culture model with inducible alpha-synuclein expression

Parkinson’s disease (PD) represents an increasing problem in society. The oligomerization of alpha-synuclein (αSyn) is a suggested key event in its pathogenesis, yet the pathological modes of action remain to be fully elucidated. To identify potential disease-modifying therapeutics and to study αSyn-mediated toxic mechanisms, we established cell lines with inducible overexpression of different αSyn constructs: αSyn, αSyn coupled to the fluorescence protein Venus (αSyn-Venus), and αSyn coupled to the N-terminal or C-terminal part of Venus (V1S and SV2, respectively) for a bimolecular fluorescence complementation assay (BiFC). Inducibility was achieved by applying modified GAL4-UAS or Cre-loxP systems and addition of tebufenozide or 4-OH-tamoxifen, respectively. Expression constructs were stably integrated into the host genome of H4 neuroglioma cells by lentiviral transduction. We here demonstrate a detailed investigation of the expression characteristics of inducible H4 cells showing low background expression and high inducibility. We observed increased protein load and aggregation of αSyn upon incubation with DMSO and FeCl3 along with an increase in cytotoxicity. In summary, we present a system for the creation of inducibly αSyn-overexpressing cell lines holding high potential for the screening for modulators of αSyn aggregation and αSyn-mediated toxicity.

Lidocaine Attenuates Cognitive Impairment After Isoflurane Anesthesia by Reducing Mitochondrial Damage.

Mitochondrial dysfunction has been proposed to be one of the earliest triggering events in isoflurane-induced neuronal damage. Lidocaine has been demonstrated to attenuate the impairment of cognition in aged rats induced by isoflurane in our previous study. In this study, we hypothesized that lidocaine could attenuate isoflurane anesthesia-induced cognitive impairment by reducing mitochondrial damage. H4 human neuroglioma cells and 18-month-old male Fischer 344 rats were exposed to isoflurane or isoflurane plus lidocaine. Cognitive function was tested at 14days after treatment by the Barnes Maze test in male Fischer 344 rats. Morphology was observed under electron microscope, and mitochondrial transmembrane potential, electron transfer chain (ETC) enzyme activity, complex-I-IV activity, immunofluorescence and flow cytometry of annexin V-FITC binding, TUNEL assay, and Western blot analyses were applied. Lidocaine attenuated cognitive impairment caused by isoflurane in aged Fischer 344 rat. Lidocaine was effective in reducing mitochondrial damage, mitigating the decrease in mitochondrial membrane potential (ΔΨm), reversing isoflurane-induced changes in complex activity in the mitochondrial electron transfer chain and inhibiting the apoptotic activities induced by isoflurane in H4 cells and Fischer 344 rats. Additionally, lidocaine suppressed the ratio of Bax (the apoptosis-promoting protein) to Bcl-2 (the apoptosis-inhibiting protein) caused by isoflurane in H4 cells. Lidocaine proved effective in attenuating isoflurane-induced POCD by reducing mitochondrial damage.

NSPc1 polycomb protein complex binds and cross‑talks to lncRNAs in glioma H4 cells.

Recently, emerging evidence shows that a number of long non‑coding RNAs (lncRNAs) recruit polycomb group (PcG) proteins to specific chromatin loci to silence relevant gene expression. In the present study, we provided evidence that lncRNA candidates, selected by bioinformatic analysis and nervous system polycomb 1 (NSPc1), a key polycomb repressive complex 1 (PRC1) member, were highly expressed in glioma H4 cells in contrast to that noted in non‑cancerous cells. RNA binding protein immunoprecipitation (RIP) assays demonstrated that metastasis associated lung adenocarcinoma transcript 1 (MALAT1), SOX2 overlapping transcript (SOX2OT) and maternally expressed 3 (MEG3) among the 8 candidates bound to the NSPc1 protein complex in glioma H4 cells. Furthermore, overexpression of NSPc1 caused a decrease in the expression of MALAT1 and MEG3 and increased expression of SOX2OT, while NSPc1 downregulation caused the levels of all three genes to increase. Meanwhile, suppression of the expression of MALAT1 increased the expression levels of mRNA and protein of NSPc1, whereas downregulation of the expression of SOX2OT decreased NSPc1 expression. Moreover, a significant decrease in cell growth and increased cell apoptosis were observed in the transfected H4 cells by MTT assay and flow cytometric analysis. The results showed that the reduced co‑expression between NSPc1 and MALAT1/SOX2OT decreased the proliferation and promoted the death of H4 cells more obviously than the respectively decrease in expression of NSPc1, MALAT1 and SOX2OT. Remarkably, the influence of a simultaneously decreased expression of NSPc1 and SOX2OT on promoting cell apoptosis was more obvious than the total effect of the separate downregulation of NSPc1 and SOX2OT on accelerating cell death. However, that impact was partially counteracted in the silencing of the co‑expression of MALAT1 and NSPc1. Furthermore, they cooperated to affect transcription of p21 and OCT4.Briefly, these data suggest NSPc1 polycomb protein complex binding and cross‑talk to lncRNAs in glioma H4 cells, offering new insight into the important function of polycomb protein complex and lncRNA interactions in glioma cells and provide a novel view of potential biomarkers and targets for the diagnosis and therapy of glioma.

Adenovirus-Mediated CRM197 Sensitizes Human Glioma Cells to Gemcitabine by the Mitochondrial Pathway.

The cross-reacting material 197 (CRM197) is a mutation of the diphtheria toxin. The protein of CRM197 was used successfully for the therapy of various tumors in the recent studies. In this study, the recombinant adenoviruses containing the CRM197gene(AdCRM197) were used to enhance the cellar toxicity of gemcitabine in human glioma U87, U251, and H4 cells. MTT assay and flow cytometric analysis were performed to test the apoptosis of the U87, U251 and H4 cells with the combined treatment of AdCRM197 plus gemcitabine. Western blotting analyses were carried out to detect the cell apoptosis of the mitochondrial pathway. And the xenograft nude mice were used to observe the enhanced antitumor effect of AdCRM197 in vivo. AdCRM197 sensitizes human glioma cells to gemcitabine in vitro by the mitochondrial pathway. Tumor volume was inhibited and survival time was prolonged in the U251 or U87 xenografted nude mice with gemcitabine plus AdCRM197. The enhanced antitumor effect of AdCRM197 was also detected by the immunohistochemical analyses and TUNEL staining. The authors found that AdCRM197 sensitized the human glioma to gemcitabine not only in vitro but also in vivo. They provide the first evidence that adenovirus-mediated CRM197 may be a potential chemosensitizing agent for the treatment of cancer. The diphtheria toxin is of great toxicity that even one molecule of diphtheria toxin is enough to kill one cell. However, because of the high toxicity, the diphtheria toxin would kill the packing cells when it is being packaged into the recombinant viruses. Therefore, the diphtheria toxin is hard to be used in the gene therapy for virus vectors. The cross-reacting material 197 (CRM197) is a mutation of the diphtheria toxin. Unlike DTA, CRM197 exhibit a weak toxicity. The week toxicity of CRM197 is a good feature for the virus packaging. In the present study, we used a recombinant adenovirus which carried a CRM197 gene (AdCRM197) to enhance the cellar toxicity of gemcitabine in human glioma cells.

Midazolam and Dexmedetomidine Affect Neuroglioma and Lung Carcinoma Cell Biology In Vitro and In Vivo.

WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Several factors within the perioperative period may influence postoperative metastatic spread. Dexmedetomidine and midazolam are widely used general anesthetics during surgery. The authors assessed their effects on human lung carcinoma (A549) and neuroglioma (H4) cell lines in vitro and in vivo. Cell proliferation and migration were measured after dexmedetomidine (0.001 to 10 nM) or midazolam (0.01 to 400 μM) treatment. Expression of cell cycle and apoptosis markers were assessed by immunofluorescence. Mitochondrial membrane potential and reactive oxygen species were measured by JC-1 staining and flow cytometry. Antagonists atipamezole and flumazenil were used to study anesthetic mechanisms of action. Tumor burden after anesthetic treatment was investigated with a mouse xenograft model of lung carcinoma. Dexmedetomidine (1 nM) promoted cell proliferation (2.9-fold in A549 and 2-fold in H4 cells vs. vehicle, P < 0.0001; n = 6), migration (2.2-fold in A549 and 1.9-fold in H4 cells vs. vehicle, P < 0.0001; n = 6), and upregulated antiapoptotic proteins in vitro. In contrast, midazolam (400 μM) suppressed cancer cell migration (2.6-fold in A549 cells, P < 0.0001; n = 4), induced apoptosis via the intrinsic mitochondrial pathway, decreased mitochondrial membrane potential, and increased reactive oxygen species expression in vitro-effects partly attributable to peripheral benzodiazepine receptor activation. Furthermore, midazolam significantly reduced tumor burden in mice (1.7-fold vs. control; P < 0.05; n = 6 per group). Midazolam possesses antitumorigenic properties partly mediated by the peripheral benzodiazepine receptor, whereas dexmedetomidine promotes cancer cell survival through signaling via the α2-adrenoceptor in lung carcinoma and neuroglioma cells.

GLI2 promotes cell proliferation and migration through transcriptional activation of ARHGEF16 in human glioma cells

BackgroundThe Hedgehog (Hh) signaling pathway plays critical roles in modulating embryogenesis and maintaining tissue homeostasis, with glioma-associated oncogene (GLI) transcription factors being the main mediators. Aberrant activation of this pathway is associated with various human malignancies including glioblastoma, although the mechanistic details are not well understood.MethodsWe performed a microarray analysis of genes that are differentially expressed in glioblastoma U87 cells overexpressing GLI2A, the active form of GLI2, relative to the control cells. Chromatin immunoprecipitation and dual-luciferase assays were used to determine whether Rho guanine nucleotide exchange factor 16 (ARHGEF16) is a downstream target of GLI2. Then, transwell migration, EdU and soft-agar colony formation assays were employed to test effects of ARHGEF16 on glioma cancer cell migration and proliferation, and the effects of GLI2/ARHGEF16 signaling on tumor growth were examined in vivo. Finally, we performed yeast two-hybrid assay, Co-IP and GST-pull down to identify factors that mediate effects of ARHGEF16.ResultsWe found that ARHGEF16 mRNA level was upregulated in U87 cells overexpressing GLI2A relative to control cells. GLI2 binds to the ARHGEF16 promoter and activates gene transcription. Glioma cells U87 and U118 overexpressing ARHGEF16 showed enhanced migration and proliferation relative to the control cells, while knockdown of ARHGEF16 in H4 cells led to decreased cell proliferation compared to the control H4 cells. In contrast to the promoting effect of GLI2A overexpression on glioma xenograft growth, both GLI2 inhibition and ARHGEF16 knockdown retarded tumor growth. Cytoskeleton-associated protein 5 (CKAP5) was identified as an interaction protein of ARHGEF16, which is important for the stimulatory effects of ARHGEF16 on glioma cell migration and proliferation.ConclusionsThese results suggest that therapeutic strategies targeting the GLI2/ARHGEF16/CKAP5 signaling axis could inhibit glioma progression and recurrence.

C-Fos/microRNA-18a feedback loop modulates the tumor growth via HMBOX1 in human gliomas

Glioma is one of the most aggressive and lethal human cancers in central nervous system (CNS). Recent studies have identified many dysregulated microRNAs (miRNA, miR) in human glioma, which are a class of small non-coding RNA molecules. Increasing data have shown that miR-18a plays significant roles in several tumors. However, its effects on glioma are unclear. In this study, we found the elevated expression of c-Fos and miR-18a in tissues of human glioma patients and glioma cells. Then the miR-18a inhibitor or c-Fos siRNA were transfected into glioma cells line H4 to determine their effects on H4 cells. MTT assay showed that both miR-18a inhibitor and si-c-Fos suppressed the H4 cell proliferation. Transwell assay showed the reduced cell migration by miR-18a inhibitor and si-c-Fos in H4 cells. The increased level of H4 cells apoptosis by miR-18a inhibitor and si-c-Fos was also determined. Moreover, knockout of c-Fos decreased the miR-18a level, while miR-18a inhibitor reduced the c-Fos level in H4 cells. Added with the results of ChIP assay, this report showed a positive feedback between c-Fos and miR-18a. Finally, luciferase assay showed that HMBOX1 was directly targeted by miR-18a in H4 cells, and the HMBOX1 siRNA reversed the effects of miR-18a inhibitor on cell proliferation, migration and apoptosis of H4 cells. In conclusion, our study determine that c-Fos/miR-18a feedback loop promotes the tumor growth of gliomas by HMBOX1, providing important clues for understanding the key roles of transcription factor mediated mRNA-miRNA functional network in the regulation of gliomas.

Mesenchymal stromal cells attenuate sevoflurane-induced apoptosis in human neuroglioma H4 cells

BackgroundInhalation of sevoflurane can induce neuronal apoptosis, cognitive impairment and abnormal behaviors. Bone marrow mesenchymal stem cells (MSCs) can secret neurotrophic factors and cytokines to protect from oxidative stress-related neuronal apoptosis. However, whether MSCs can protect from sevoflurane-induced neuronal apoptosis and the potential mechanisms are unclear.MethodsA non-contact co-culture of MSCs with human neuroglioma H4 cells (H4 cells) was built. H4 cells were co-cultured with MSCs or without MSCs (control) for 24 h. The co-cultured H4 cells were exposed to 4% sevoflurane for 6 h. The levels of caspase-3, reactive oxygen species (ROS), adenosine triphosphate (ATP), and the release of cytochrome C were determined by Western blot and fluorescence assay.ResultsSevoflurane exposure significantly elevated the levels of cleaved caspase 3 and Bax in H4 cells. However, these phenomena were significantly offset by the co-culture with MSCs in H4 cells. Co-culture with MSCs before, but not after, sevoflurane exposure, significantly attenuated sevoflurane-induced ROS production in H4 cells. MSCs prevented sevoflurane-mediated release of cytochrome C from the mitochondria and production of ATP in H4 cells.ConclusionsOur study indicated that soluble factors secreted by MSCs attenuated the sevoflurane-induced oxidative stress and apoptosis of neuronal cells by preserving their mitochondrial function.

PO-207 The role of RSU-1 in glioma cells metastasis

IntroductionRas Suppressor-1 (RSU-1) was recently found to be associated with Focal Adhesion (FA) proteins. The main objective of this research work was the in vitrocharacterisation of a panel of glioma cancer cells in terms of aggressiveness, and the investigation of RSU-1 role on invasion of glioma cancer cells.Material and methodsA panel of four human neuroblastoma cell lines was used (H4, SW1088, A172, U87-MG). Invasion assay with matrigel-coated transwell and soft agar growth assay were performed in order to characterise the aggressiveness of glioma cell lines. The RSU-1 expression for glioma cells was tested by real time PCR and immunoblotting. Finally, glioma cells were transfected with siRNA against RSU-1 in order to find out the role of RSU-1 in glioma cells.Results and discussionsIn order to assess the invasive potential of the four glioma cell lines, a transwell invasion assay was performed and A172 and U87-MG cells found to be more invasive than H4 and SW1088 cells. To determine the aggressiveness of the studied cell lines, soft agar assay was also performed. The number of colonies for the U87-MG and A172 was significantly larger than the H4 and SW1088, with the latter cell lines only forming a few small colonies.We then sought to find out whether RSU-1 gene is differentially expressed in the four cell lines and whether its expression is correlated with invasiveness. It was found that the more aggressive A172 and U87-MG cell lines, overexpress RSU-1 compared to the less aggressive H4 and SW1088 cell lines.Subsequently, two cell lines were selected to be used for further experiments, H4 and A172 which are the least aggressive and more aggressive cells, respectively. Our results show that upon RSU-1 silencing, the invasion of A172 cells was significantly decreased whereas invasion of H4 cells was increased with respective changes observed in the expression of Matrix Metalloproteinase 13 (MMP13), a fundamental protease in cancer cell metastasis.ConclusionResults confirmed that the A172 and U87-MG glioma cells are more aggressive than H4 and SW1088. Also, RSU-1 was found to be overexpressed in most aggressive cells in comparison to less aggressive cell lines. More aggressive A172 cells lacking RSU-1 showed decreased invasion while H4 cells showed increased invasion. Collectively, RSU-1 found to be critical for glioma cell invasion and further investigation of the implicated molecular mechanism is underway.

PAX5‐Induced Expression of Endogenous Mucolipin‐2 (MCOLN2) Gene in Human Glial and Neuronal Cell Lines: A Potential Gene Complementation Therapy Approach for Mucolipidosis IV

The loss of function in the Transient Receptor Potential Mucolipin‐1 (TRPML1) protein, encoded by the Mucolipin‐1 (MCOLN1) gene, is known to cause the neurodegenerative disease Mucolipidosis type IV (MLIV). Characteristics of MLIV are motor problems, cognitive dysfunction, achlorhydria, cataracts, and blindness caused by retinal cell death. The Ashkenazi Jew population is most afflicted by the disease, and MLIV has no known cure. The Mucolipin ion channels consist of TRPML1, ‐2, and ‐3 proteins, which are encoded by MCOLN1, ‐2, and ‐3 genes, respectively. They are known to serve as non‐selective cation channels located within endosomes and lysosomes and play a role in endosome‐lysosome fusion. Previous research indicates that TRPML1 and TRPML2 proteins share a high degree of homology, and we hypothesize that TRPML2, which has no known association to clinical disease, could substitute for the loss of functional TRPML1 in MLIV, resulting in a rescue of the disease phenotype. In order to study the potential therapeutic effects of TRPML2 in MLIV, we must first show that it is expressed in the brain, one of the tissues most affected by MLIV. We have previously discovered PAX5 as the transcriptional activator for MCOLN2 and have shown that MCOLN2 expression could be heterologously induced in both human neuroglioma (H4) cells and human embryonic kidney 293 (HEK‐293) cell lines. Previous reports demonstrated that MCOLN2 has tissue‐specific expression with little to no detectable transcripts in brain tissue. However, our preliminary research has detected endogenous levels of MCOLN2 transcripts in human H4 and neuroblastoma (SH‐SY5Y) cells. Moreover, to induce the expression of endogenous MCOLN2, we transduced SH‐SY5Y cells with adenovirus and lentivirus vectors containing the PAX5 cDNA. PAX5 serves as a B cell‐specific activator protein with tissue‐specific expression pattern as well. Standard reverse‐transcription polymerase chain reaction (RT‐PCR) and real‐time quantitative RT‐PCR both revealed MCOLN2 expression in SH‐SY5Y cells at 48 and 72 hours post‐transduction. We show that PAX5 transcriptionally activates and increases endogenous MCOLN2 expression in neuronal cells that are central to studying MLIV. Future studies include In‐Cell Western assay with an anti‐TRPML2 antibody and transcriptome analysis of PAX5‐treated cells to determine global gene expression. These results and future studies will further explore the therapeutic potential of gene complementation to rescue the cellular phenotype in MLIV disease.Support or Funding InformationThis work was partly funded by NIH R15 NS101594.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Indomethacin induced glioma apoptosis involving ceramide signals

Nonsteroidal anti-inflammatory drugs (NSAIDs) are increasingly implicated in the prevention and treatment of cancers apart from their known inhibitory effects on eicosanoid production. One of the NSAIDs, indomethacin, in particular shows promising antineoplastic outcome against glioma. To extend such finding, we here studied in human H4 and U87 glioma cells the possible involvement of the ceramide/protein phosphatase 2 A (PP2A)/Akt axis in the indomethacin-induced apoptosis. We found that the induced apoptosis was accompanied by a series of biochemical events, including intracellular ceramide generation, PP2A activation, Akt dephosphorylation, Mcl-1 and FLICE inhibiting protein (FLIP) transcriptional downregulation, Bax mitochondrial distribution, and caspase 3 activation. Such events were also duplicated with a cell-permeable C2-ceramide and Akt inhibitor LY294002. Pharmacological inhibition of ceramide synthase by fumonisin B1 and PP2A by okadaic acid moderately attenuated indomethacin-induced Akt dephosphorylation along with the apoptosis. Results suggested that the ceramide/PP2A/Akt axis is involved in the apoptosis and a possible cyclooxygenase-independent target for indomethacin. Furthermore, apoptosis regulatory proteins such as Mcl-1 and FLIP are potential downstream effectors of this axis and their downregulation could turn on the apoptotic program.

Autophagy induction by hispidulin provides protection against sevoflurane-induced neuronal apoptosis in aged rats

AimSevoflurane is a general anesthetic, which has been found to cause cognitive and memory deficit in elderly. This study is designed to explore the neuroprotective effect of hispidulin, a natural flavone compound, against sevoflurane-induced cognitive dysfunction in aged rats. Materials and methodsHuman neuroglioma cell line H4 was used as cellular model in our study. The apoptosis of H4 cells was determined by DNA fragmentation and flow cytometry. The autophagy of H4 cells was determined by observing GFP-LC3 II puncta and flow cytometry. The levels of marker proteins for apoptosis and autophagy were determined by western blot. The neuroprotective effect of hispidulin was also examined in aged rat model. The impairment of cognitive function by sevoflurane exposure was evaluated by Morris water maze. The apoptotic cell death in hippocampus was measured by TUNEL assay. ResultsOur results showed that hispidulin significantly induced autophagy in H4 cells, which contributed to its protective activity against sevoflurane-induced apoptosis. In addition, our results showed that hispidulin triggered autophagy in AMPK-dependent way. Moreover, the neuroprotective effect hispidulin was verified in aged rat model, which showed that pretreatment with hispidulin significantly attenuated sevoflurane-induced cognitive dysfunction. Meanwhile, our findings revealed that the neuroprotectionin rat model by hispidulin was associated with activation of autophagy and AMPK signaling pathway. ConclusionThe findings in this present study highlight that hispidulin offers neuroprotection against sevoflurane-induced cognitive dysfunction, which is mediated by autophagy induction through activating AMPK signaling. The present study provides novel information about the underlying mechanism for the neuroprotective activity of hispidulin.

Hispidulin prevents sevoflurane— Induced memory dysfunction in aged rats

AimAs a widely used general anesthetic, sevoflurane has been found to induce cognitive and memory defectsin the elderly. This may increase the risk of Alzheimer’s disease. This study explores the neuroprotective effect of hispidulin, a natural flavone compound, against sevoflurane-induced memory dysfunction. MethodsThe effect of sevoflurane exposure on memory function was evaluated by novel object recognition and Y-maze testing using an aged rat model. The apoptotic cell death in the hippocampus of rats was assessed using a TUNEL assay. The levels of protein markers for cell apoptosis in the hippocampus were examined by western blot. The effect of sevoflurane and hispidulin on the accumulation of Aβ was also examined. In addition, the attenuating effect of hispidulin on sevoflurane-induced neuroinflammation was assessed by measuring the expression of pro-inflammatory cytokines and the translocation of NF-κB p65 from cytosol to nucleus. The activation of Nrf2 in the hippocampus was also detected. Moreover, the effect of hispidulin on sevoflurane-induced apoptosis, Aβ accumulation, and neuroinflammation was also examined in human neuroglioma H4 cells, which served as an in vitro model.To further examine the role of Nrf2 in the neuroprotective activity of hispidulin against sevoflurane-neurotoxicity, H4 cells were transfected with Nrf2 targeting siRNA, which led to a significant reduction in Nrf2 expression. ResultsBoth novel object recognition and Y-maze testing showed that sevoflurane significantly impaired the memory of aged rats, which was significantly reversed by pretreatment with hispidulin. Mechanistically, our findings revealed that hispidulin significantly attenuated sevoflurane-induced apoptotic cell death, Aβ accumulation, and neuroinflammation. In agreement with in vivo studies, hispidulin was also able to attenuate sevoflurane-induced apoptosis, increases of Aβ levels, and neuroinflammation in H4 cells. Moreover, our results showed that Nrf2 activation mediated the neuroprotective effect of hispidulin against sevoflurane-induced neurotoxicity by demonstrating that knockdown of Nrf2 in H4 cells significantly compromised its protective effects. ConclusionAs our study provides in vitro and in vivo evidence that hispidulin can offer protection against sevoflurane-induced neurological dysfunction, hispidulin has the potential to be a neuroprotective agent that can improve the cognitive and memory function of elderly patients undergoing anesthesia.