Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Astrocytes synthesize only the B2 chain of laminin and that this chain is sufficient to stimulate neurite outgrowth. In this study, we have examined laminin B1 and B2 promoter constructs in various cell types in order to understand the transcriptional regulation of laminin B2 gene in astrocytes. Comparison of nuclear factor binding by Southwestern analysis with the highly active B2 promoter fragment revealed different patterns of nuclear factor binding. In HepG2 cells, two proteins of 105 and 98 kDa were identified while, in primary astrocytes, human U251 and rat C6 glioma cells, a greater number of nuclear proteins ranging from 43 to 212 kDa were detected. The laminin B1 promoter construct was inactive in transient transfection experiments in astrocytes yet active in the HepG2 hepatoma cells which synthesize both the B1 and B2 chains. In contrast, the laminin B2 promoter construct was active in both astrocytes and HepG2 cells. These results are consistent with the lack of laminin B1 mRNA expression in astrocytes and suggest that the differential regulation of the laminin B1 and B2 gene is controlled at the transcriptional level. Delineation of the 5'-flanking regions responsible for basal levels of B2 laminin promoter activity revealed a silencer-like segment between -830 and -224 which reduced promoter activity. Deletion analysis further revealed that B2 laminin promoter possesses a highly active short promoter (-94 to +106) and basal transcriptional activity resides within -61 to +106. DNase 1 footprinting, gel-shift competition assays and site-directed mutagenesis of a highly active short promoter revealed that this region contained binding sites for cell-type nuclear factors. The shortest construct containing only residues -21 to +106 was inactive in HepG2 and U251 glioma cells. In primary astrocytes, however, this construct showed a high level of transcriptional activity. Deletion of 47 bp (+59 to +106) in 5'-UTR completely blocked promoter activity in astrocytes confirming that this downstream region is important for transcriptional activity in primary astrocytes. Together, these results suggest that astrocytes may utilize mutually exclusive transcription factors and regulatory sequences, in addition to common factors in the control of the laminin B2 promoter.
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PMID:Regulatory sequences for the transcription of the laminin B2 gene in astrocytes. 922 5

The expression of the gene encoding the rat beta 1-adrenergic receptor is suppressed by glucocorticoids (Kiely et al., 1994). Within the 3.2-kb 5'-flanking region of the promoter, two potential glucocorticoid response elements (GREs) at -950 and -2791 relative to the translational ATG were identified. Characterization of the glucocorticoid-responsive sequences in the 5'-flanking region of the beta 1-adrenergic receptor gene was explored in rat C6 glioma cells and human HepG2 hepatoma cells using transient expression of beta 1-adrenergic receptor-luciferase fusion genes. The ability of glucocorticoids to suppress luciferase expression was not altered when the most 5'-localized GRE was deleted. Deleting the potential GRE at -950, in contrast, abolished glucocorticoid-induced suppression of the beta 1-adrenergic receptor-luciferase gene transcription. A 25-bp element containing the GRE sequence between nucleotides -950 and -926 confers glucocorticoid-dependent inhibition of transcription to a neutral promoter. Gel mobility shift assays with the alpha-subunit of the human glucocorticoid receptor (hGR alpha) expressed in reticulocyte lysates demonstrated specific binding to the 25-bp sequence harboring the putative GRE. We report an inhibitory GRE in the promoter of the rat beta 1-adrenergic receptor gene that is conserved among the rat, human, and mouse genes.
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PMID:Identification of a glucocorticoid repressor domain in the rat beta 1-adrenergic receptor gene. 925 49

In order to understand if antiplatelet drugs possess direct antineoplastic property, we tested the apoptotic effect of 5 popularly marketed antiplatelet drugs in Taiwan in 6 cultured cancer cell lines (Hep 3B hepatocarcinoma, U87-MG malignant glioma, PC-3 prostate adenocarcinoma, HeLa cervical adenocarcinoma, HL-60 preleukemia and K-562 chronic myelogenous leukemia). While acetylsalicylate and flunarizine exerted no effect on these cancer cells, pentoxifyline (PTX), dipyridamole (DYA) and ticlopidine hydrochloride (T. HCl) displayed a time and dose-dependent apoptotic effect on them except for HL-60 and K-562 cells. PTX induced apoptosis in U87-MG, Hep 3B and HeLa cells, DYA in HeLa cells, while T. HCl in U87-MG, Hep 3B, PC-3 and HeLa cells. Adriamycin also provoked apoptotic effect in all 6 cell lines but neither PTX, DYA nor T. HCl acted synergy with adriamycin to HeLa cells, implicating that they may share a similar pathway for inducing apoptosis. Therefore, our results show that the antiplatelet drugs do possess antineoplastic property in vitro. A co-administration of antiplatelet drugs is noteworthy for an alternative adjunctive therapy in cancer patients.
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PMID:Antiplatelet drugs induce apoptosis in cultured cancer cells. 938 74

Transiently transfected cell lines and transgenic mice were used to study the transcriptional activity of the 5'-flanking region of the catalase gene. Fragments of the 5'-flanking region of the rat catalase gene ranging in length from 3,421 base pairs (bp) to 69 bp were fused to the chloramphenicol acetyltransferase (CAT) reporter gene, and the transcriptional activity of the reporter gene was measured following transient transfection in three cell lines: a human hepatoma cell line (HepG2), a porcine kidney epithelial cell line (LLCPK1), and a human glioma cell line (U-138 MG). The 3,421-bp fragment of the 5'-flanking region resulted in a high level of expression of the reporter gene in all three cell lines. Shorter fragments of the 5'-flanking region resulted in a decrease in the level of CAT reporter expression that varied among the three cell lines, implying the presence of tissue-specific regulatory sites. To study the tissue-specific regulation of the catalase promoter, transgenic mice containing the 3,421-bp 5'-flanking sequence attached to the CAT reporter gene were produced, and CAT expression was measured in various tissues of three independent transgenic lines. CAT activity was consistently high in muscle tissue (heart, skeletal muscle, and diaphragm) and low in most other tissues studied, particularly in liver and kidney. In contrast, the endogenous expression of catalase is low in muscle and high in liver and kidney; thus, the tissue-specific expression of the reporter gene driven by the 3,421-bp fragment of the 5'-flanking region of the catalase gene was not similar to the expression of the endogenous catalase gene.
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PMID:Analysis of the transcriptional activity of the 5'-flanking region of the rat catalase gene in transiently transfected cells and in transgenic mice. 939 52

Novel anti-neoplastic agents such as gene targeting vectors and encapsulated carriers are quite large (approximately 100-300 nm in diameter). An understanding of the functional size and physiological regulation of transvascular pathways is necessary to optimize delivery of these agents. Here we analyze the functional limits of transvascular transport and its modulation by the microenvironment. One human and five murine tumors including mammary and colorectal carcinomas, hepatoma, glioma, and sarcoma were implanted in the dorsal skin-fold chamber or cranial window, and the pore cutoff size, a functional measure of transvascular gap size, was determined. The microenvironment was modulated: (i) spatially, by growing tumors in subcutaneous or cranial locations and (ii) temporally, by inducing vascular regression in hormone-dependent tumors. Tumors grown subcutaneously exhibited a characteristic pore cutoff size ranging from 200 nm to 1.2 microm. This pore cutoff size was reduced in tumors grown in the cranium or in regressing tumors after hormone withdrawal. Vessels induced in basic fibroblast growth factor-containing gels had a pore cutoff size of 200 nm. Albumin permeability was independent of pore cutoff size. These results have three major implications for the delivery of therapeutic agents: (i) delivery may be less efficient in cranial tumors than in subcutaneous tumors, (ii) delivery may be reduced during tumor regression induced by hormonal ablation, and (iii) permeability to a molecule is independent of pore cutoff size as long as the diameter of the molecule is much less than the pore diameter.
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PMID:Regulation of transport pathways in tumor vessels: role of tumor type and microenvironment. 953 85

Sensitivity of CD95-mediated apoptosis has been reported to vary during cell cycle progression (FEBS Lett. (1997) 412, 91-93). Here, we report that three human glioma cell lines with different p53 status (i) undergo growth arrest and synchronous cell cycle re-entry after prolonged serum deprivation, (ii) do not exhibit cell cycle-related changes in CD95 expression at the cell surface, and (iii) do not exhibit cell cycle-related changes in susceptibility to DC95 ligand-induced apoptosis. In contrast, cell cycle-specific activity was demonstrated for various cancer chemotherapy drugs. Further, CD95 expression and susceptibility to CD95 ligand-induced apoptosis does not vary during cell cycle progression of Jurkat T cells, HeLa cervical carcinoma and HepG2 hepatocellular carcinoma cells. These results do not support a role for the cell cycle phase as an important predictor of vulnerability to CD95-mediated apoptosis.
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PMID:CD95-mediated apoptosis: no variation in cellular sensitivity during cell cycle progression. 972 Sep 15

A humanized ONS-M21 antibody (hM21) against human medulloblastoma and glioma cells was engineered as a single-chain Fv fragment (scFv), and its ability to internalize into tumor cells was evaluated by conjugation with ricin A. The scFv of hM21 (schM21) was easily purified from E.coli by one-step affinity column chromatography. Purified schM21 bound to a medulloblastoma ONS-76 cell with almost equal antigen-binding activity of hM21-Fab fragment. Furthermore, the schM21-ricin A conjugate inhibited the growth of ONS-76 cells, but not that of antigen-negative hepatoma HuH-7 cells, suggesting that the schM21 can be internalized after binding to antigen-positive cells. Thus, schM21 could be expected to act as a novel carrier of diagnostic and therapeutic agents for brain tumors.
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PMID:A humanized single-chain Fv fragment with high targeting potential against human malignant gliomas. 989 84

A recent case of angiomyolipoma (AML) with a prominent component of polygonal epithelioid cells is described. A 27-year-old Japanese male with tuberous sclerosis presented with massive abdominal tumors increasing progressively in size. The patient died of respiratory disturbance and the autopsy revealed massive tumors in the bilateral kidneys, liver and lymph nodes, subependymal giant cell glioma of the brain and lymphangiomyomatosis of the lungs. The giant tumors were an unusual type of AML with a component of polygonal epithelioid cells, which showed a hepatocellular carcinoma-like pattern in some areas. Smooth muscle components comprising spindle cells, short or plump spindle cells and polygonal epithelioid cells frequently exhibited positive staining for HMB-45 but negative staining for epithelial cell markers. The unusual AML presented in this case was thought to be of low-grade malignancy and slow growing. It has been suggested that angiomyolipomas with diffuse areas of epithelioid cell component are potentially malignant. Immunostainings positive for HMB-45 but negative for epithelial cell markers are considered to be useful in differentiating AML with polygonal epithelioid cell component from other tumors, especially from renal cell carcinoma and hepatocellular carcinoma.
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PMID:Multiple giant angiomyolipomas with a polygonal epithelioid cell component in tuberous sclerosis: an autopsy case report. 995 47

Transcription of the asparagine synthetase (AS) gene is induced by amino acid deprivation. The present data illustrate that this gene is also under transcriptional control by carbohydrate availability. Incubation of human HepG2 hepatoma cells in glucose-free medium resulted in an increased AS mRNA content, reaching a maximum of about 14-fold over control cells after approx. 12 h. Extracellular glucose caused the repression of the content of AS mRNA in a concentration-dependent manner, with a k1/2 (concentration causing a half-maximal repression) of 1 mM. Fructose, galactose, mannose, 2-deoxyglucose and xylitol were found to maintain the mRNA content of both AS and the glucose-regulated protein GRP78 in a state of repression, whereas 3-O-methylglucose did not. Incubation in either histidine-free or glucose-free medium also resulted in adaptive regulation of the AS gene in BNL-CL.2 mouse hepatocytes, rat C6 glioma cells and human MOLT4 lymphocytes, in addition to HepG2 cells. In contrast, the steady-state mRNA content of GRP78 was unaffected by amino acid availability. Transient transfection assays using a reporter gene construct documented that glucose deprivation increases AS gene transcription via elements within the proximal 3 kbp of the AS promoter. These results illustrate that human AS gene transcription is induced following glucose limitation of the cells.
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PMID:Transcriptional regulation of the human asparagine synthetase gene by carbohydrate availability. 1008 39

Glucocorticoids are known to influence the ability of cells to undergo apoptosis, directly inducing apoptosis in thymocytes while inhibiting it in hepatoma and carcinoma cells. Dexamethasone, a synthetic glucocorticoid, is reported to induce partial resistance to certain anticancer drugs in glioma cell lines. In the present study, the effect of dexamethasone on apoptosis of glioma and astrocytoma cell lines was investigated. Exposure of D384 human astrocytoma and C6 rat glioma cells to staurosporine induced apoptosis as judged by the formation of condensed nuclei and caspase activation. Pre-treatment of cells with dexamethasone caused a reduction in staurosporine-induced apoptosis. In addition, dexamethasone also conferred protection against the induction of apoptosis by anticancer agents including camptothecin and etoposide. The protective effect of dexamethasone was dose and time dependent, with maximal protection obtained with concentrations equal to or greater than 100 nM and a pre-incubation period of at least 24h. The earliest significant inhibition was seen with a pre-incubation period of 8h. Co-treatment with the glucocorticoid receptor antagonist RU38486 abolished the effect of dexamethasone, indicating that the protection due to dexamethasone is mediated via this receptor. Dexamethasone was found to induce a time-dependent up-regulation of Bcl-x(L) protein expression. However, the ability of cytochrome c/dATP to activate the caspase cascade in cytosolic extracts of D384 cells was unaffected by prior exposure of the cells to dexamethasone (1 microM) for 48 h. In conclusion, dexamethasone inhibits the induction of apoptosis in astrocytoma cells, probably via an up-regulation of Bcl-x(L), which could prevent cytochrome c release from mitochondria and subsequent caspase activation. Since glucocorticoids are often used in the treatment of gliomas to relieve cerebral oedema, the inhibition of apoptosis by these compounds could potentially interfere with the efficacy of chemotherapeutic drugs.
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PMID:Dexamethasone pre-treatment interferes with apoptotic death in glioma cells. 1068 82


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