Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thirty-nine glial tumours (28 glioblastomas (GB) and 11 low-grade gliomas) were investigated with DNA microarrays to reveal a possible specific gene expression profile. Unsupervised classification through hierarchical cluster analysis identified two groups of tumours, the first composed of low-grade gliomas and the second mainly composed of GB. Nine genes were identified as most informative: seven were over-expressed in low-grade gliomas and under-expressed in GB; on the contrary, two genes, insulin-like growth factor binding protein 2 (IGFBP-2) and cell division cycle 20 homologue (CDC20), were over-expressed in GB and under-expressed in low-grade tumours. This same genetic profile was confirmed by reverse transcriptase polymerase chain reaction. Immunohistochemistry for IGFBP-2 was positive in 88.8% of the cases of GB and in only one low-grade glioma, whilst CDC20 immunostained 74.1% of the cases of GB and none low-grade glioma. This was confirmed in an additional series of cases studied with immunohistochemistry only. In conclusion, over-expression of mRNA levels of IGFBP-2 and CDC20 is highly related to GB, IGFBP-2 and CDC-20 gene and protein expressions are strongly correlated, and IGFBP-2 and CDC20 immunopositivity can be useful for the identification of GB in small biopsies.
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PMID:Gene expression profiling in glioblastoma and immunohistochemical evaluation of IGFBP-2 and CDC20. 1895 66

MicroRNAs (miRNAs) are small noncoding regulatory RNAs that reduce stability and/or translation of fully or partially sequence-complementary target mRNAs. Recent evidence indicates that miRNAs can function both as tumor suppressors and as oncogenes. It has been demonstrated that in glioblastoma multiforme miR-21 and 221 are upregulated whereas miR-128 and 181 are downregulated. Expression of miR-21, 221, 128a, 128b, 128c, 181a, 181b, 181c was studied using real-time quantitative reverse transcriptase polymerase chain reaction and northern blotting for human astrocytic tumors with different grade of malignancy. miR-21 and 221 were overexpressed in glioma samples, whereas miRNA 181b was downregulated compared with normal brain tissue. miRNA-21 was hyperexpressed in all tumor samples whereas higher levels of miRNA-221 were found in high-grade gliomas. This study is the first analysis of miRNAs in astrocytic tumor at different stages of malignancy. The different expression pattern observed in tumors at different stages of malignancy is probably dependent on the cell-specific repertoire of target genes of tumors sharing different molecular pathways activity and suggests miRNAs may have also a place in diagnosis and staging of brain tumors.
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PMID:miR-21 and 221 upregulation and miR-181b downregulation in human grade II-IV astrocytic tumors. 1915 78

Low-frequency ultrasound (LFU) and bradykinin (BK) have been shown separately to increase the permeability of the blood-tumor barrier (BTB) in the rat model of C6 glioma. This study examined the hypothesis that the combination of LFU and low-dose BK has a synergistic effect on increasing the permeability of BTB and explored the possible underlying mechanism including the involvement of tight junction (TJ). The rats were divided into six groups: control group, LFU group, BK group, 2/3LFU + 1/2BK group, 5/6LFU + 2/3BK group, and LFU + BK group. The BTB permeability was assessed by Evans blue extravasation. The mRNA and protein expressions of TJ-related proteins ZO-1, occludin, and claudin-5 were determined by reverse transcriptase-polymerase chain reaction, immunohistochemistry, immunolocalization, and Western blot test. BTB permeability increased in all the experimental groups, accompanied by opening of local TJ of the BTB, observed by transmission electron microscopy, and decreased mRNA and protein expressions of ZO-1, occludin, and claudin-5. In addition, there was a further increase in BTB permeability and a further reduction in the expressions of TJ-related proteins in 5/6LFU + 2/3BK and LFU + BK groups, compared with LFU or BK group. These results indicate that LFU and low-dose BK applied in combination act in a synergistic manner to increase BTB permeability. The down-regulation of TJ-related proteins ZO-1, occludin, and claudin-5 may be one of the underlying mechanisms of the increase in BTB permeability induced by LFU and BK.
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PMID:Synergistic effect of low-frequency ultrasound and low-dose bradykinin on increasing permeability of the blood-tumor barrier by opening tight junction. 1932 37

MicroRNAs (miRNAs) are effective post-transcriptional regulators of gene expression and are important in many biological processes. Although the oncogenic and tumor suppressive functions of several miRNAs have been characterized, the role of miRNAs in mediating tumor invasion and migration remains largely unexplored. Recently, miR-10b was identified as an miRNA highly expressed in metastatic breast cancer, promoting cell migration and invasion. Here, we performed real-time reverse transcriptase polymerase chain reaction (RT-PCR) assays on 43 glioma samples (17 glioblastoma, 6 anaplastic astrocytoma, 10 low-grade astrocytoma, 6 oligodendroglioma and 4 ependymoma) and 6 glioma cell lines. We found that miR-10b expression was upregulated in all glioma samples compared to non-neoplastic brain tissues. The expression levels of miR-10b were associated with higher grade glioma. In addition, mRNA expressions of RhoC and urokinase-type plasminogen activator receptor (uPAR), which were thought to be regulated by miR-10b via HOXD10, were statistically significantly correlated with the expression of miR-10b (p < 0.001, p = 0.001, respectively). Also, protein expression levels of RhoC and uPAR were associated with expression levels of miR-10b (p = 0.009, p = 0.014, respectively). Finally, multifocal lesions on enhanced MRI of 7 malignant gliomas were associated with higher expression levels of miR-10b (p = 0.02). Our data indicated that miR-10b might play some role in the invasion of glioma cells.
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PMID:MicroRNA-10b is overexpressed in malignant glioma and associated with tumor invasive factors, uPAR and RhoC. 1953 18

Medulloblastoma is the most common brain tumor of childhood. Emerging molecular targets in medulloblastoma include neurotrophin and neuropeptide receptors. In the present study, we have examined the influence of brain-derived neurotrophic factor (BDNF)/TrkB receptor- and gastrin-releasing peptide receptor (GRPR)-mediated signaling on the viability of human medulloblastoma cells. The expression of TrkB and GRPR was confirmed by immunohistochemistry and mRNA for both BDNF and GRPR was detected by reverse transcriptase polymerase chain reaction in Daoy, D283, and ONS76 cells. Treatment with BDNF significantly inhibited the viability of Daoy and D283, but not ONS76 cells, measured with the MTT assay. Neither the GRPR agonists GRP and bombesin nor the GRPR antagonist RC-3095 affected cell viability. Because previous findings have indicated that the viability of glioma cells might be enhanced by GRP when combined with the cAMP phosphodiesterase-4 (PDE4) inhibitor rolipram, we also examined the effects of rolipram alone or combined with GRP on cell viability. Rolipram significantly reduced the viability of all three cell lines, and the inhibitory effect of rolipram in Daoy cells was not modified by cotreatment with GRP. The results suggest that BDNF/TrkB and PDE4, but not the GRPR, regulate the viability of medulloblastoma cells.
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PMID:BDNF and PDE4, but not the GRPR, regulate viability of human medulloblastoma cells. 1964 24

Acquisition of insidious invasiveness by malignant glioma cells involves multiple genetic alterations in signaling pathways. Slit2, a chemorepulsive factor, controls cell migration of neuronal and glial cells during development and inhibits chemotaxic migration of various types of cells in vitro. However, the role of Slit2 in vitro remains controversial, and the biological significance of Slit2 expression in cancer cell invasion in vivo has not yet been determined. In the present study, we characterized the effects of Slit2 expression on the migration and invasion of invasive glioma cells in vitro and in vivo. By reverse transcriptase polymerase chain reaction (PCR) analyses, Slit2 was found to be expressed at lower levels in primary glioma specimens and invasive glioma cells compared with normal human brain cells and astrocytes. Ectopic expression of Slit2 or treatment with recombinant Slit2 on glioma cells attenuates cell migration and invasion through inhibition of Cdc42 activity in vitro. Cellular depletion of Robo1, a cognate receptor for Slit2, prevented Slit2 inhibition of Cdc42 activity and glioma cell migration. In vivo, expression of Slit2 by invasive SNB19 glioma cells markedly inhibited glioma cell infiltration into the brain of mice. Moreover, impediment of glioma cell invasion by Slit2 did not affect the expression of N-cadherin and beta-catenin in glioma cells. These results provide the first evidence demonstrating that Slit2-Robo1 inhibits glioma invasion through attenuating Cdc42 activity in vitro and in the brain. Understanding the mechanisms of Slit2-Robo1 inhibition of glioma cell invasion will foster new treatments for malignant gliomas.
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PMID:Slit2 inhibits glioma cell invasion in the brain by suppression of Cdc42 activity. 2000 33

This study was performed to determine whether endothelial-monocyte-activating polypeptide (EMAP) II increases the permeability of the blood-tumor barrier (BTB) in the rat model of C6 glioma, and whether EMAP II opens the BTB by affecting tight junction (TJ) associated proteins zonula occluden-1 (ZO-1), occludin and claudin-5. The rats were divided into eight groups randomly: control group, EMAPII 0h group, EMAPII 0.5h group, EMAPII 1h group, EMAPII 2h group, EMAPII 3h group, EMAPII 6h group and EMAPII 12h group. The BTB permeability was assessed by Evans blue extravasation. The mRNA and protein expressions of ZO-1, occludin, and claudin-5 were determined by reverse transcriptase-polymerase chain reaction, western blot, and immunohistochemistry assays. The BTB permeability significantly increased after EMAP II injection in different doses (40ng/kg, 80ng/kg and 160ng/kg). The BTB permeability started to increase from 0.5h, reached a peak at 1h, and finally returned to the level of EMAP II 0h group after EMAP II injection at dose of 80ng/kg. The mRNA and protein expression levels of ZO-1, occludin and claudin-5 were significantly decreased after EMAP II injection. This study demonstrates for the first time that EMAP II increases the permeability of BTB selectively, and the possible mechanism is associated with the down-regulation of ZO-1, occludin and claudin-5.
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PMID:Endothelial-monocyte-activating polypeptide II increases blood-tumor barrier permeability by down-regulating the expression levels of tight junction associated proteins. 2008 91

Extended studies on mouse embryos during the earliest stages of development are limited owing to both the large number of preimplantation embryos usually required and the difficulties in manipulating embryos after implantation; an in vitro model for embryogenesis would therefore be useful. Recently, blastocyst-derived mouse embryonic stem (ES) cells have been reported to differentiate in vitro to generate embryoid bodies (EBs) which form endoderm, mesoderm and ectoderm, thereby partially mimicking early stages of murine development. After 7 days of differentiation, EBs consisted of 6-10 x 10(3) cells. Confocal laser scanning microscopy of EBs after 13-14 days of differentiation (diameter 650-800 mum) revealed that they were vital, whereas similar-sized human malignant glioma (U 343 MG) cell spheroids showed cell death in the core region. To evaluate the potential of this system as an in vitro model of embryonic erythropoiesis, the EBs were analysed for the presence of erythropoietin (EPO) mRNA by reverse transcriptase-mediated polymerase chain reaction (RT-PCR) and we adapted a 2,7-diaminofluorene (DAF)-based staining method to detect haemoglobin in situ. DAF-positive cells appeared at day 5-6 of differentiation, whereas EPO mRNA was found in undifferentiated ES cells and in EBs at all stages of differentiation. Early expression of EPO mRNA prior to the onset of erythropoiesis implies that EPO may have a yet unknown role during early development. Apart from its potential to investigate embryonic erythropoiesis, this in vitro model may be useful for pharmacological and toxicological studies focused on early stages of development.
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PMID:Differentiating embryonic stem cells as an in vitro model of early erythropoiesis. 2065 Jan 9

In previous studies we found expression of the protein colligin 2 (heat shock protein 47 (HSP47), SERPINH1) in glioma neovasculature while not in normal brain tissue. Generally, the regulation of heat shock gene expression in eukaryotes is mediated by heat shock factors (HSF). In mammals, three heat shock transcription factors, HSF-1, -2, and -4, have been isolated. Here we investigated the relation between the expression of colligin 2 and these heat shock factors at the mRNA level using real-time reverse transcriptase PCR (qRT-PCR) in different grades of astrocytic tumorigenesis, viz., low-grade glioma and glioblastoma. Endometrium samples, representing physiological angiogenesis, were included as controls. Since colligin 2 is a chaperon for collagens, the gene expression of collagen I (COL1A1) was also investigated. The blood vessel density of the samples was monitored by expression of the endothelial marker CD31 (PECAM1). Because NG2-immunopositive pericytic cells are involved in glioma neovascularization, the expression of NG2 (CSPG4) was also measured.We demonstrate overexpression of HSF2 in both stages of glial tumorigenesis (reaching significance only in low-grade glioma) and also minor elevated levels of HSF1 as compared to normal brain. There were no differences in expression of HSF4 between low-grade glioma and normal brain while HSF4 was downregulated in glioblastoma. In the endometrium samples, none of the HSFs were upregulated. In the low-grade gliomas SERPINH appeared to be slightly overexpressed with a parallel 4-fold upregulation of COL1A1, while in glioblastoma there was over 5-fold overexpression of SERPINH1 and more than 150-fold overexpression of COL1A1. In both the lowgrade gliomas and the glioblastomas overexpression of CSPG4 was found and overexpression of PECAM1 was only found in the latter. Our data suggest that the upregulated expression of colligin 2 in glioma is accompanied by upregulation of COL1A1, CSPG4, HSF2 and to a lesser extent, HSF1. Further studies will unravel the association of these factors with colligin 2 expression, possibly leading to keys for therapeutic intervention.
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PMID:Overexpression of Colligin 2 in Glioma Vasculature is Associated with Overexpression of Heat Shock Factor 2. 2107 23

Malignant gliomas are characterized by their invasiveness and angiogenesis. Matrix metalloproteinases (MMPs) degrade extracellular matrix and create a more permissive environment for cell invasion. We aimed to investigate for the presence of inter- and intratumoral heterogeneity in MMP-2 messenger RNA (mRNA) expression by means of quantitative analysis and to evaluate its prognostic impact in glioma patients. Representative sections from the center and periphery of tumors resected en bloc were taken fresh for study, stained with hematoxylin/eosin for histological evaluation, and immunohistochemically analyzed for Ki-67. MMP-2 mRNA expression was evaluated by real-time reverse transcriptase polymerase chain reaction (RT-PCR). There was MMP-2 expression in all analyzed tumors. By topographical dissection of surgical specimens, we found no differences in cell proliferation or density but significant differences with regard to MMP-2 mRNA expression between central and peripheral regions, being highest at the center of malignant gliomas. MMP-2 mRNA expression showed no prognostic influence on overall or disease-free survival. Our results demonstrate that MMP-2 is differentially expressed in central and peripheral regions of gliomas. Further studies are necessary to clarify the significance of these findings and their possible relevance in clinical practice.
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PMID:Quantitative analysis of matrix metalloproteinase-2 mRNA expression in central and peripheral regions of gliomas. 2133 14


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