Expression and roles of Wilms' tumor 1-associating protein in glioblastoma.

Glioblastoma is a diffusely growing malignant brain tumor and among the most aggressive of all tumors. Wilms' tumor 1-associating protein (WTAP) is a nuclear protein that has been associated with regulation of proliferation and apoptosis. Although its dynamic expression and physiological functions in vascular cells have been reported, those in other cells are largely unknown. Here, we show for the first time that WTAP is overexpressed in glioblastoma. Moreover we found that WTAP regulates migration and invasion of glioblatoma cells. Specific knockdown by siRNA or overexpression by cDNA regulated migration and invasion of cancer cells. In xenograft study, WTAP overexpression made cancer cells more tumorigenic. In the investigation for its underlying mechanism, we found that the activity of epidermal growth factor receptor can be regulated by WTAP. These results reveal a novel function of WTAP and suggest its clinical application.

Regulatory role of mouse epidermal growth factor-like protein 8 in thymic epithelial cells.

Unlike epidermal growth factor-like protein 7 (EGFL7), which is a secreted protein implicated in the regulation of blood vessel formation and cell migration, little is known about the physiological function of EGFL8. Thymic epithelial cells (TECs) play a pivotal role in T-cell development by regulating cellular interactions and expression of growth factors, cytokines, and chemokines. In order to investigate the functional role of EGFL8 in TECs, we transfected TECs with an EGFL8-expressing vector to overexpress EGFL8 protein and with an EGFL8 siRNA to knockdown EGFL8 expression. EGFL8-silenced TECs showed significant increase in the number of adherent thymocytes by enhancing the expression of intercellular adhesion molecule-1 (ICAM-1), while the overexpression of EGFL8 inhibited the adherence of TECs to thymocytes by suppressing ICAM-1 expression. Furthermore, in vitro co-culture study revealed that knockdown of EGFL8 facilitated the maturation of thymocytes to CD4(+) and CD8(+) single-positive populations. These regulatory effects of EGFL8 in T-cell development were further confirmed by the results that knockdown of EGFL8 enhanced the expression of genes involved in thymopoiesis, such as interleukin-7 (IL-7), granulocyte/macrophage-colony stimulating factor (GM-CSF), and thymus-expressed chemokine (TECK). Our data show that EGFL8 exerts inhibitory effects on TECs and thymocytes, suggesting that EGFL8 acts as a negative regulatory molecule in the development of T cells in the mouse thymus.

Cancer spheres from gastric cancer patients provide an ideal model system for cancer stem cell research.

Cancer stem cells have been hypothesized to drive the growth and metastasis of tumors. Because they need to be targeted for cancer treatment, they have been isolated from many solid cancers. However, cancer stem cells from primary human gastric cancer tissues have not been isolated as yet. For the isolation, we used two cell surface markers: the epithelial cell adhesion molecule (EpCAM) and CD44. When analyzed by flow cytometry, the EpCAM(+)/CD44(+) population accounts for 4.5% of tumor cells. EpCAM(+)/CD44(+) gastric cancer cells formed tumors in immunocompromised mice; however, EpCAM(-)/CD44(-), EpCAM(+)/CD44(-) and EpCAM(-)/CD44(+) cells failed to do so. Xenografts of EpCAM(+)/CD44(+) gastric cancer cells maintained a differentiated phenotype and reproduced the morphological and phenotypical heterogeneity of the original gastric tumor tissues. The tumorigenic subpopulation was serially passaged for several generations without significant phenotypic alterations. Moreover, EpCAM(+)/CD44(+), but not EpCAM(-)/CD44(-), EpCAM(+)/CD44(-) or EpCAM(-)/CD44(+) cells grew exponentially in vitro as cancer spheres in serum-free medium, maintaining the tumorigenicity. Interestingly, a single cancer stem cell generated a cancer sphere that contained various differentiated cells, supporting multi-potency and self-renewal of a cancer stem cell. EpCAM(+)/CD44(+) cells had greater resistance to anti-cancer drugs than other subpopulation cells. The above in vivo and in vitro results suggest that cancer stem cells, which are enriched in the EpCAM(+)/CD44(+) subpopulation of gastric cancer cells, provide an ideal model system for cancer stem cell research.

Curcumin attenuates TNF-α-induced expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and proinflammatory cytokines in human endometriotic stromal cells.

Curcumin, a naturally occurring polyphenolic compound from Curcuma longa, has long been used in folk medicine as an antiinflammatory remedy in Asian countries. Endometriosis is a chronic gynecological inflammatory disorder in which immune system deregulation may play a role in its initiation and progression. A number of mediators, including cell adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1); proinflammatory cytokines such as tumour necrosis factor-α (TNF-α), interleukin-1 (IL-1), IL-6 and IL-8; and chemokines such as monocyte chemotactic protein-1 (MCP-1), play key roles in the pathogenesis of endometriosis. The aim of our study was to explore the effect of curcumin on the expression of these critical molecules in human ectopic endometriotic stromal cells isolated from women with endometriosis. Endometriotic stromal cells treated with curcumin showed marked suppression of TNF-α-induced mRNA expression of ICAM-1 and VCAM-1. Curcumin treatment also significantly decreased the TNF-α-induced cell surface and total protein expression of ICAM-1 and VCAM-1 in a dose-dependent manner. In addition, treatment of endometriotic stromal cells with curcumin markedly inhibited TNF-α-induced secretion of IL-6, IL-8 and MCP-1. Furthermore, curcumin inhibited the activation of transcription factor NF-κB, a key regulator of inflammation, in human endometriotic stromal cells. These findings suggest that curcumin may have potential therapeutic uses in the prevention and treatment of endometriosis.

SNAI1 is involved in the proliferation and migration of glioblastoma cells.

Glioblastoma is the most common type of astrocytoma in the brain. Due to its high invasiveness and chemoresistance, patients with advanced stage of glioblastoma have a poor prognosis. SNAI1, an important regulator of epithelial-mesenchymal transition, has been associated with metastasis in various carcinoma cells. However, its roles in glioblastoma cells have been poorly characterized. To examine roles of SNAI1 in glioblastoma cells, we knockdowned SNAI1 expression using siRNA. SNAI1 siRNA increased the expression level of E-cadherin and decreased that of vimentin. In the water-soluble tetrazolium salt (WST-1) assay, SNAI1 siRNA inhibited the proliferation of U87-MG and GBM05 glioblastoma cells. Moreover, in the Boyden chamber assay and Matrigel invasion assay, SNAI1 siRNA inhibited serum-induced migration and invasion of glioblastoma cells. These results suggested that SNAI1 is involved in the proliferation and migration of glioblastoma cells.

5-Hydroxymethylfurfural from black garlic extract prevents TNFα-induced monocytic cell adhesion to HUVECs by suppression of vascular cell adhesion molecule-1 expression, reactive oxygen species generation and NF-κB activation.

5-Hydroxymethylfurfural (5-HMF) is a common Maillard reaction product; the reaction occurs during heat-processing and the preparation of many types of foods and beverages. Although 5-HMF has been proposed to have harmful effects, recently, its beneficial effects, including antioxidant, cytoprotective and antitumor effects have become increasingly apparent. It was found recently that a chloroform extract of aged black garlic shows antiinflammatory properties when administered to human umbilical vein endothelial cells (HUVECs). This study investigated the antiinflammatory potential of 5-HMF purified from the chloroform extract of aged black garlic in tumor necrosis factor-α (TNF-α)-stimulated HUVECs. Treatment of HUVECs with 5-HMF strongly suppressed TNF-α-induced cell surface and total protein expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1) as well as their mRNA expression. In addition, 5-HMF significantly inhibited TNF-α-induced reactive oxygen species formation, and markedly reduced THP-1 monocyte adhesion to TNF-α-stimulated HUVECs. Furthermore, 5-HMF significantly inhibited NF-κB transcription factor activation in TNF-α-stimulated HUVECs. The data provide new evidence of the antiinflammatory properties of 5-HMF in support of its potential therapeutic use for the prevention and management of vascular diseases such as atherosclerosis through mechanisms involving the inhibition of VCAM-1 expression and NF-κB activation in vascular endothelial cells.

Chloroform extract of aged black garlic attenuates TNF-α-induced ROS generation, VCAM-1 expression, NF-κB activation and adhesiveness for monocytes in human umbilical vein endothelial cells.

Aged black garlic is a type of fermented garlic (Allium sativum) which has been used in Oriental countries for a long time because of various biological properties of garlic derivatives. The current study explored the potential of the chloroform extract of aged black garlic (CEABG) in attenuating the activities of adhesion molecules in tumor necrosis factor-α (TNF-α)-stimulated human umbilical vein endothelial cells (HUVECs). The study was performed on HUVECs that were pretreated with 30 µg/mL of CEABG before TNF-α treatment. Treatment of HUVECs with CEABG significantly inhibited TNF-α-induced reactive oxygen species (ROS) formation. HUVECs treated with CEABG showed markedly suppressed TNF-α-induced mRNA expression of VCAM-1, but little alteration in ICAM-1 and E-selectin mRNA expression. CEABG treatment also significantly decreased the TNF-α-induced cell surface and total protein expression of VCAM-1 without affecting ICAM-1 and E-selectin expression. In addition, treatment of HUVECs with CEABG markedly reduced THP-1 monocyte adhesion to TNF-α-stimulated HUVECs. Furthermore, CEABG significantly inhibited NF-κB transcription factor activation in TNF-α-stimulated HUVECs. The data provide new evidence of the antiinflammatory properties of CEABG that may have a potential therapeutic use for the prevention and treatment of vascular diseases such as atherosclerosis through mechanisms involving the inhibition of VCAM-1 expression and NF-κB activation in vascular endothelial cells.

Regulation of cerebrospinal fluid production by caffeine consumption.

BACKGROUND: Caffeine is the most commonly consumed psycho-stimulant in the world. The effects of caffeine on the body have been extensively studied; however, its effect on the structure of the brain has not been investigated to date. RESULTS: In the present study we found that the long-term consumption of caffeine can induce ventriculomegaly; this was observed in 40% of the study rats. In the caffeine-treated rats with ventriculomegaly, there was increased production of CSF, associated with the increased expression of Na(+), K(+)-ATPase and increased cerebral blood flow (CBF). In contrast to the chronic effects, acute treatment with caffeine decreased the production of CSF, suggesting 'effect inversion' associated with caffeine, which was mediated by increased expression of the A1 adenosine receptor, in the choroid plexus of rats chronically treated with caffeine. The involvement of the A1 adenosine receptor in the effect inversion of caffeine was further supported by the induction of ventriculomegaly and Na+, K+-ATPase, in A1 agonist-treated rats. CONCLUSION: The results of this study show that long-term consumption of caffeine can induce ventriculomegaly, which is mediated in part by increased production of CSF. Moreover, we also showed that adenosine receptor signaling can regulate the production of CSF by controlling the expression of Na(+), K(+)-ATPase and CBF.

The role of hedgehog signaling during gastric regeneration.

BACKGROUND: Hedgehog signaling plays critical roles during embryonic development. It is also involved in tissue regeneration and carcinogenesis in various adult tissues. Moreover, it regulates the maintenance of cancer stem cells and adult stem cells. Although hedgehog signaling is important in gastric carcinogenesis, its role in gastric regeneration has not been previously examined. In the present study, we evaluated the expression and roles of hedgehog signaling during gastric regeneration. METHODS: Gastric ulcers were induced by serosal application of an acetic acid solution in mice. Sham-operated mice served as controls. The proliferation of gastric progenitor cells was studied using bromodeoxyuridine (BrdU). The expression of hedgehog signaling molecules and the differentiation of gastric progenitor cells were examined by immunohistochemical staining and Western blotting. RESULTS: One day after the induction of gastric ulcer, the proliferation of gastric progenitor cells increased; however, the expression of hedgehog signaling molecules, including sonic hedgehog (Shh), Indian hedgehog (Ihh), desert hedgehog (Dhh), and patched (Ptch1) decreased at the ulcer margin. From 5 days after the induction of gastric ulcer, newly generated gastric glands and their differentiation were observed at the ulcer margin. The expression of hedgehog signaling molecules gradually increased in the newly generated gastric glands of the ulcer margin. Cyclopamine, a specific inhibitor of hedgehog signaling, significantly inhibited the differentiation of mucous cells and parietal cells during the gastric regeneration process. CONCLUSION: The above results suggest that hedgehog signaling is involved in the differentiation of gastric progenitor cells during the gastric ulcer repair process.

Reduction of ischemia-induced cerebral injury by all-trans-retinoic acid.

Ischemia-induced cerebral injury evolves over a longer period than previously believed through post-ischemic inflammation. Retinoic acid (RA) has been shown to exert cytoprotective effects on several cells, but its effects on ischemia-induced cerebral injury have been poorly characterized. The aim of the present study was to examine the effects of all-trans-RA on ischemia-induced cerebral injury and elucidate the underlying mechanism. All-trans-RA treatment reduced the size of the ischemia-induced cerebral infarct. To elucidate the underlying mechanism, ischemia-induced cerebral inflammation was studied by examination of expressions of interleukin 1beta (IL-1beta) and ED-1. RA treatment significantly reduced the cerebral inflammation. Moreover, cerebral ischemic induction of cyclooxygenase-2 (COX-2) and CCAAT/enhancer binding protein beta (C/EBPbeta), which binds to the COX-2 promoter, was also inhibited by RA. These results suggest that RA can reduce ischemia-induced cerebral injury by an anti-inflammatory action, which may be effected via inhibition of C/EBPbeta-mediated COX-2 induction.

Hedgehog signaling regulates the survival of gastric cancer cells by regulating the expression of Bcl-2.

Gastric cancer is the second most common cause of cancer deaths worldwide. The underlying molecular mechanisms of its carcinogenesis are relatively poorly characterized. Hedgehog (Hh) signaling, which is critical for development of various organs including the gastrointestinal tract, has been associated with gastric cancer. The present study was undertaken to reveal the underlying mechanism by which Hh signaling controls gastric cancer cell proliferation. Treatment of gastric cancer cells with cyclopamine, a specific inhibitor of Hh signaling pathway, reduced proliferation and induced apoptosis of gastric cancer cells. Cyclopamine treatment induced cytochrome c release from mitochondria and cleavage of caspase 9. Moreover, Bcl-2 expression was significantly reduced by cyclopamine treatment. These results suggest that Hh signaling regulates the survival of gastric cancer cells by regulating the expression of Bcl-2.

Up-regulation of VEGF expression by NGF that enhances reparative angiogenesis during thymic regeneration in adult rat.

Angiogenesis is important for adult tissue regeneration as well as normal development. Vascular endothelial growth factor (VEGF) is a unique potent angiogenic factor, and plays an essential role in regulating angiogenesis during embryonic development, normal tissue growth, and tissue regeneration. Recent evidence shows that nerve growth factor (NGF) also plays a role as an angiogenic regulator as well as a well-known neurotrophic factor. The aim of this study was to investigate whether thymus regeneration accompanies reparative angiogenesis and also to evaluate whether the thymic expression of VEGF is regulated by NGF in vivo and in vitro. Here, we show that high VEGF mRNA and protein levels are concomitant with reparative angiogenesis that occurs dramatically during regeneration following acute involution induced by cyclophosphamide (CY) in the rat thymus. Fluorescent thymus angiography using FITC-dextran showed that thymic regeneration is associated with a much denser capillary network compared with normal control thymus. Furthermore, the expressions of NGF and TrkA were highly increased during thymic regeneration. We also show that NGF mediates thymic epithelial induction of VEGF expression in vitro and in vivo. Taken together, our results suggest that NGF-mediated VEGF up-regulation in thymic epithelial cells may contribute to reparative angiogenesis during thymic regeneration in adult.

RANKL stimulates proliferation, adhesion and IL-7 expression of thymic epithelial cells.

In many clinical situations which cause thymic involution and thereby result in immune deficiency, T cells are the most often affected, leading to a prolonged deficiency of T cells. Since only the thymic-dependent T cell production pathway secures stable regeneration of fully mature T cells, seeking strategies to enhance thymic regeneration should be a key step in developing therapeutic methods for the treatment of these significant clinical problems. This study clearly shows that receptor activator of NF-kappaB ligand (RANKL) stimulates mouse thymic epithelial cell activities including cell proliferation, thymocyte adhesion to thymic epithelial cells, and the expression of cell death regulatory genes favoring cell survival, cell adhesion molecules such as ICAM-1 and VCAM-1, and thymopoietic factors including IL-7. Importantly, RANKL exhibited a significant capability to facilitate thymic regeneration in mice. In addition, this study demonstrates that RANKL acts directly on the thymus to activate thymus regeneration regardless of its potential influences on thymic regeneration through an indirect or systemic effect. In light of this, the present study provides a greater insight into the development of novel therapeutic strategies for effective thymus repopulation using RANKL in the design of therapies for many clinical conditions in which immune reconstitution is required.

Nerve growth factor stimulates proliferation, adhesion and thymopoietic cytokine expression in mouse thymic epithelial cells in vitro.

Thymic epithelial cells, which constitute a major component of the thymic microenvironment, provide a crucial signal for intrathymic T cell development and selection. Neuroimmune networks in the thymic microenvironment are thought to be involved in the regulation of T cell development. NGF is increasingly recognized as a potent immunomodulator, promoting "cross-talk" between various types of immune system cells. The present study clearly shows that NGF stimulates mouse thymic epithelial cell activities in vitro including cell proliferation, thymocyte adhesion to thymic epithelial cells, and the expression of cell adhesion molecules such as ICAM-1 and VCAM-1, and thymopoietic factors including IL-7, GM-CSF, SDF-1, TARC and TECK. Thus, our data are of considerable clinical importance showing that trophic NGF activity could be used to enhance the thymus regeneration and develop methods to improve host immunity when the immune function is depressed due to thymic involution.

Aspirin-induced blockade of NF-kappaB activity restrains up-regulation of glial fibrillary acidic protein in human astroglial cells.

The marked induction of glial fibrillary acidic protein (GFAP) has been observed in astrocytes during neuropathological processes accompanying reactive gliosis; however, the precise molecular mechanism(s) underlying this GFAP induction remains poorly resolved. Therefore, in this study, we examined whether the change of nuclear factor-kappa B (NF-kappaB) activity can influence GFAP expression levels. Aspirin, widely used to prevent NF-kappaB activity, reduced the levels of GFAP mRNA and protein in human astroglial cells including human glioblastoma A172 cells and primary human brain astrocyte cells (HBAs). Furthermore, aspirin inhibited the effects of hypoxic injury on the up-regulation of GFAP expression in HBAs. We confirmed the repressive effect of aspirin on GFAP transcription by GFAP promoter-driven reporter assay and found that one NF-kappaB binding site conserved in the mouse and human GFAP gene promoters is critical for this effect. To further delineate whether NF-kappaB is directly involved in the regulation of GFAP gene expression, we transfected A172 cells with an expression vector encoding a super-repressor IkappaBalpha protein (IkappaBalpha-SR) to specifically inhibit NF-kappaB activity and found the marked reduction of GFAP protein levels in IkappaBalpha-SR-transfectant cells. Taken together, our results suggest that NF-kappaB may play pivotal roles in GFAP gene expression.

Effects of retinoic acid on ischemic brain injury-induced neurogenesis.

Neurogenesis can be induced by pathological conditions such as cerebral ischemia. However the molecular mechanisms or modulating reagents of the reactive neurogenesis after the cerebral ischemia are poorly characterized. Retinoic acid (RA) has been shown to increase neurogenesis by enhancing the proliferation and neuronal differentiation of forebrain neuroblasts. Here, we examined whether RA can modulate the reactive neurogenesis after the cerebral ischemia. In contrast to our expectation, RA treatment decreased the reactive neurogenesis in subventricular zone (SVZ), subgranular zone (SGZ) and penumbral region. Furthermore, RA treatment also decreased the angiogenesis and gliosis in penumbral region.

Expression of nerve growth factor is upregulated in the rat thymic epithelial cells during thymus regeneration following acute thymic involution.

Neuroimmune networks in the thymic microenvironment are thought to be involved in the regulation of T cell development. Nerve growth factor (NGF) is increasingly recognized as a potent immunomodulator, promoting "cross-talk" between various types of immune system cells. The present study describes the expression of NGF during thymus regeneration following acute involution induced by cyclophosphamide in the rat. Immunohistochemical stain demonstrated not only the presence of NGF but also its upregulated expression mainly in the subcapsular, paraseptal, and perivascular epithelial cells, and medullary epithelial cells including Hassall's corpuscles in both the normal and regenerating thymus. Biochemical data obtained using Western blot and RT-PCR supported these results and showed that thymic extracts contain NGF protein and mRNA, at higher levels during thymus regeneration. Thus, our results suggest that NGF expressed in these thymic epithelial cells plays a role in the T lymphopoiesis associated with thymus regeneration during recovery from acute thymic involution.

Trichostatin A increases the thermosensitivity of human glioblastoma A172 cells.

Trichostatin A (TSA), histone deacetylase inhibitor, shows a promising therapeutic effect on cancer cells in combination with radiotherapy or chemotherapy. However, little has been reported on the combined treatment of TSA with hyperthermia. Here, we have assessed the effect of TSA/hyperthermia on human glioblastoma A172 cells and found that TSA increases the thermosensitivity of A172 cells, resulting in cellular apoptosis. The underlying mechanism of this effect consists of reduction in the level of phosphorylated STAT3 (Tyr705), a transcription factor required for survival of A172 cells, which leads to down-regulation of STAT3 target genes, cyclin D1 and Bcl-xL. Furthermore, the level of VEGF mRNA was also decreased by TSA/hyperthermia, suggesting the antiangiogenic effect of TSA/hyperthermia on human glioblastoma. Collectively, our results show the role of TSA as a chemical thermosensitizer, suggesting the possible therapeutic application of combined treatment of TSA/hyperthermia on STAT3-dependent tumors.

CDNA array analysis of gene expression profiles in brain of mice exposed to manganese.

This study is performed to detect changes of gene expression in substantia nigra (SN) and striatum in manganese (Mn)-exposed mice brain. The cDNA array is a recently developed molecular biological method that can detect the differential expression of several hundreds of genes simultaneously and is therefore advantageous in the study of trace metal intoxication effect at the genetic level. Using this technology, we discovered 5 genes in the mouse striatum and 9 genes in SN changed by more than 50% following Mn exposure. Depression were observed in two genes (neural cell adhesion protein BIG2, heavy neurofilament subunit genes) in striatum and three genes (light neurofilament subunit, brain acyl-CoA synthetase II, heavy neurofilament subunit genes) in the SN. However three genes (N-acetylglucosaminyltransferase I, S100beta, and synaptonemal complex protein I genes) in striatum and six genes (noggin, striatin, Ost oncogene, S100beta, calcium/calmodulin-dependent protein kinase kinase beta, and N-acetylglucosaminyltransferase I genes) in SN were elevated following Mn exposure. Immunohistochemical study revealed that protein levels of S100beta also increased following Mn treatment. Activated astrocytes overexpressing S100beta are invariably and intimately associated with decreased expression of heavy and light neurofilament subunits which is a distinguishing feature of neurodegeneration by Mn exposure. All our findings suggested that neuronal degenerations occur in SN as well as striatum of mice exposed to Mn.

Epidermal growth factor-like domain 8 inhibits the survival and proliferation of mouse thymocytes.

Thymic epithelial cells (TECs) play a critical role in T-cell development through their intercellular interactions and by producing various soluble proteins, such as growth factors, cytokines and chemokines. In this study, we report a new role for epidermal growth factor-like domain 8 (EGFL8) in the regulation of the survival and proliferation of mouse thymocytes. Mouse recombinant EGFL8 (rEGFL8) protein was produced using an E. coli system and its biological role in mouse thymocytes was determined. The injection of rEGFL8 in mice in vivo resulted in a decrease in the weight of the thymus, as well as in the number of total thymocytes; rEGFL8 also inhibited thymocyte proliferation and induced thymocyte apoptosis. Furthermore, rEGFL8 suppressed the expression of the Notch downstream targets, Hes1 and Hey1, in mouse thymocytes and TECs, indicating that EGFL8 negatively regulates the Notch signaling pathway in these cells. The identification of the role of EGFL8 in thymocytes may aid in the determination of the fate of thymocytes during T-cell development.