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: UMLS:C0017636 (glioblastoma)
18,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several studies have shown a decrease in blood perfusion and oxygen partial pressure (pO2), and an increase in interstitial fluid pressure (IFP) with increasing tumor size. However, it is not evident if the elevated IFP is a key parameter responsible for the poor perfusion and oxygenation of solid tumors. To this end, IFP and pO2 were measured in nine human tumor xenografts in immunodeficient mice at a fixed tumor size (approximately 250 mm3). IFP and pO2 were also measured as a function of tumor volume in one human colon adenocarcinoma (LS174T) and in one human glioblastoma (HGL-9). In LS174T tumors IFP did not vary with size (P < .07); however, median pO2 decreased from approximately 35 mm Hg in 100-mm3 tumors to approximately 15 mm Hg in tumors of approximately 500 mm3 (P < 0.001). In HGL-9 tumors an inverse correlation between IFP and pO2 was found; IFP increased (P < 0.001) and pO2 decreased (P < 0.001) with increasing tumor size. At a fixed tumor size of 250 mm3 no correlation was found between mean IFP and median pO2 (P < 0.5) or between the mean IFP and the hypoxic fraction (pO2 < 2.5 mm Hg) (P < 0.7) in the nine tumors studied. The absence of a general relationship between IFP and pO2 could result in part from differences in vascular resistance between tumors. For example, a high geometric resistance to blood flow on the arterial side will lead to a low IFP and blood flow, whereas an elevation of the venous resistance will reduce blood flow and increase IFP.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Lack of general correlation between interstitial fluid pressure and oxygen partial pressure in solid tumors. 853 98

The bacterial enzyme cytosine deaminase (CD) catalyzes the conversion of 5-fluorocytosine (5-FC) to the lethal 5-fluorouracil (5-FU) and so provides a useful system for selective killing of gene-modified mammalian tumor cells. Cloning of the CD gene from Escherichia coli and expression in human tumor cell lines enabled these cells to convert 3H-labeled 5-FC into 3H-5-FU. Two CD-expressing human tumor cell lines (adenocarcinoma cell line KM12 and glioblastoma cell line T1115) became 200-fold more sensitive to 5-FC than the nonexpressing parental cell lines. At least 90% of the cells are killed within 7 days. CD-expressing cells are able to kill nonexpressing cells when grown in the same culture flask (bystander effect). The CD gene may be used as a suicide system for in situ chemotherapy or as a safety mechanism abrogating the expression of other genes.
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PMID:Cytosine deaminase gene as a potential tool for the genetic therapy of colorectal cancer. 854 59

Primary malignant brain tumors are among the most difficult human malignancies to manage. Other common tumors such as in the lung or breast generally can be cured if caught at an early stage. A 2 cm adenocarcinoma in the peripheral lung field without mediastinal or systemic metastasis can be cured. A small breast carcinoma which has not invaded into the regional lymph nodes can generally be removed with the expectation of permanent control. However, a 1 cm glioblastoma in the anterior right frontal lobe, even with gross total resection and maximum adjunctive radiation, will recur and cause death within a year or two. There is no realistic possibility of cure or even long-term survival. These patients pose unusual management problems. They require different medications such as anticonvulsants and steroids. There are neurocognitive problems and the quality of life is usually worse than for the other common malignancies. They require a multidisciplinary approach with health care providers skilled in a variety of disciplines. Malignant gliomas have two components. There is the main bulk of the tumor (the ring enhancing portion seen on the MRI) and the infiltrating portion than cannot be seen by any imaging method. Local control has improved over the past ten years, but control of the infiltrating portion is still lacking. It is likely that some form of biologic approach will be needed to seek out and kill these infiltrating cells that travel with such ease within the white matter tracts of the brain. Perhaps selective delivery of self-destruct genes to these cells will be possible. Perhaps the search and destroy potential of the immune system can be harnessed. If so, this incurable cancer may some day be brought under control. The effort involved will be extensive both in the laboratory and in the clinic.
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PMID:Multidisciplinary approach to malignant gliomas. 879 16

The antiproliferative flavonoid, quercetin, is limited in its pharmacological utility by its low water solubility. In this paper, we describe the synthesis of two quercetin analogues prepared by linking the hydroxyl group at the 3- or 5-position of the flavonoid to the 1-hydroxyl group of myo-inositol-2-phosphate via a succinate diester linkage. The resulting conjugates were found to have dramatically enhanced water solubility relative to quercetin; the 5-linked quercetin analogue 2 had a water solubility of > 300 mg/mL at 20 degrees C. Comparison of the in vitro cytotoxicity and antiproliferative activity of conjugate 2 with those of quercetin toward cultured human colon adenocarcinoma (SW480) and human glioblastoma (U87MG) cells indicated that this modification of quercetin does not significantly diminish its activity in these assays.
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PMID:Synthesis of inositol 2-phosphate-quercetin conjugates. 887 Feb 39

Flavopiridol (NSC 649890, L86-8275), a potent inhibitor of cyclin-dependent kinase 1/p34cdc2 phosphorylation and kinase activity, is currently undergoing Phase I clinical testing as a potential antineoplastic agent. Previous studies have suggested that flavopiridol is cytostatic but not cytotoxic when applied to exponentially growing cells. In the present study, various human tumor cell lines were assayed for trypan blue exclusion and ability to form colonies after exposure to flavopiridol under a variety of growth conditions. When log phase A549 non-small cell lung cancer cells were examined 72 h after the start of a 24-h flavopiridol exposure, as many as 90% of the cells accumulated trypan blue. A 24-h exposure to 250-300 nM resulted in trypan blue uptake in 50% of A549 cells at 72 h and a 50% reduction in colony formation. Similar results were observed in HCT8 ileocecal adenocarcinoma, T98G glioblastoma, MCF-7 breast adenocarcinoma, and HL-60 leukemia cells. With A549 cells, identical results were obtained in actively growing logarithmic phase cells and growth-arrested confluent cells. Treatment with the DNA synthesis inhibitor aphidicolin only minimally affected the cytotoxicity of flavopiridol. In contrast, the RNA synthesis inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole or the protein synthesis inhibitor cycloheximide reduced the cytotoxicity of flavopiridol. These results suggest that: (a) flavopiridol is not only cytostatic, but also cytotoxic to a variety of human tumor cell lines; (b) flavopiridol is equally active against cycling and noncycling A549 cells; and (c) RNA and protein synthesis appear to play a role in flavopiridol-induced cytotoxicity.
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PMID:Flavopiridol: a cytotoxic flavone that induces cell death in noncycling A549 human lung carcinoma cells. 889 33

The hyperpermeability of tumor vessels to macromolecules, compared with normal vessels, is presumably due to vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) released by neoplastic and/or host cells. In addition, VEGF/VPF is a potent angiogenic factor. Removal of this growth factor may reduce the permeability and inhibit tumor angiogenesis. To test these hypotheses, we transplanted a human glioblastoma (U87), a human colon adenocarcinoma (LS174T), and a human melanoma (P-MEL) into two locations in immunodeficient mice: the cranial window and the dorsal skinfold chamber. The mice bearing vascularized tumors were treated with a bolus (0.2 ml) of either a neutralizing antibody (A4.6.1) (492 micrograms/ml) against VEGF/VPF or PBS (control). We found that tumor vascular permeability to albumin in antibody-treated groups was lower than in the matched controls and that the effect of the antibody was time-dependent and influenced by the mode of injection. Tumor vascular permeability did not respond to i.p. injection of the antibody until 4 days posttreatment. However, the permeability was reduced within 6 h after i.v. injection of the same amount of antibody. In addition to the reduction in vascular permeability, the tumor vessels became smaller in diameter and less tortuous after antibody injections and eventually disappeared from the surface after four consecutive treatments in U87 tumors. These results demonstrate that tumor vascular permeability can be reduced by neutralization of endogenous VEGF/ VPF and suggest that angiogenesis and the maintenance of integrity of tumor vessels require the presence of VEGF/VPF in the tissue microenvironment. The latter finding reveals a new mechanism of tumor vessel regression-i.e., blocking the interactions between VEFG/VPF and endothelial cells or inhibiting VEGF/VPF synthesis in solid tumors causes dramatic reduction in vessel diameter, which may block the passage of blood elements and thus lead to vascular regression.
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PMID:Time-dependent vascular regression and permeability changes in established human tumor xenografts induced by an anti-vascular endothelial growth factor/vascular permeability factor antibody. 896 29

The in vitro cytotoxicity of 8-carbamoyl-3-methylimidazo [5,1-d]-1,2,3,5-tetrazine-4(3H)-one (temozolomide) with concurrent X-irradiation was examined in a human glioblastoma cell line (U373MG) as a potential radio-chemotherapeutic treatment for malignant glioma. The combination was also examined in a human colorectal adenocarcinoma (Mawi) which had 100-fold greater O6-alkylguanine-DNA alkyltransferase (AGT) activity, a DNA-repair protein which confers resistance to temozolomide. A comparison of IC50 values indicated U373MG to be over 32-fold more sensitive to temozolomide than Mawi, but slightly more resistant to X-irradiation (p < 0.035; unpaired two-tailed t-test). Temozolomide and X-irradiation proved largely additive in U373MG by isobologram analysis (50% iso-effect) and the addition of 10 microM temozolomide to 1-2 Gy of X-irradiation increased cell kill by 2.5- to 3.0-fold. However, the combination was antagonistic in Mawi: an effect attributed to AGT induction by X-irradiation as the antagonism was removed by co-incubation with the AGT inhibitor O6-benzylguanine (O6-BG 1 microM; 24 h). O6-BG did not affect the radiation dose-response curve, but significantly increased temozolomide cytotoxicity (p < 0.015). In conclusion, the combination of temozolomide with radiation is at best additive, but could nonetheless by of considerable therapeutic benefit in glioma, particularly if administered for prolonged periods. If AGT induction compromises the efficacy of this therapy, it may be circumvented with an appropriate inhibitor such as O6-BG.
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PMID:In vitro evaluation of temozolomide combined with X-irradiation. 914 18

The structure of IL-13 receptor (IL-13R) is currently under investigation. Recently, two different human IL-13R chains, termed here IL-13R alpha and -alpha' have been cloned. We have examined various cancer and normal cell lines for the presence of mRNA for IL-13R alpha and alpha, as well as IL-4R p140 (termed beta chain) and IL-2R gamma c chains. In renal cell carcinoma, glioblastoma and ovarian carcinoma (IGROV-1) cell lines, both IL-13R alpha and alpha chains were expressed (type I IL-13R). In epidermoid, colon, ovarian adenocarcinoma (PA-1) and normal mouse fibroblast (COS7) cell lines, only IL-13R alpha' was expressed (type II IL-13R). In hematopoietic TF-1 and EBV-immortalized normal B cell lines only IL-13R alpha' but not alpha chain was expressed along with gamma c (type III or type IV IL-13R). IL-13R alpha' chain was faintly detected in human T cells. All cells expressed the IL-4Rp140 beta chain. These data provide a direct support for our model of IL-13R which consists of three different forms composed of different subunits.
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PMID:Structure of IL-13 receptor: analysis of subunit composition in cancer and immune cells. 929 58

The human lung adenocarcinoma cell line A-427 is significantly more sensitive to cytotoxic lipid peroxidation products of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) than the human lung adenocarcinoma cell line SK-LU-1, and the glioblastoma cell lines A-172 and U-87 MG. The cytotoxic effect as well as lipid peroxidation were abolished by vitamin E. The differential sensitivities of the cell lines were not correlated to the levels of lipid peroxidation products (measured as the end product malondialdehyde), indicating differences in sensitivities to products of lipid peroxidation. The high sensitivity of A-427 is apparently due to a low level of selenium-dependent glutathione peroxidase (GSH-Px), because pretreatment with sodium selenite (250 nM) increased the GSH-Px activity 3- to 4-fold and protected the cells almost completely against the growth inhibitory effect of DHA. Furthermore, 2-phenyl-1,2-benzisoselenazol-3(2H)-one (ebselen) a seleno-organic GSH-Px mimic, suppressed the cytotoxic action of DHA to A-427 in a dose dependent manner. Northern analysis demonstrated that pretreatment with sodium selenite (250 nM) was accompanied by an increased level of GSH-Px mRNA (1.8-fold) in A-427 cells, while the level remained unchanged under the same conditions in DHA/EPA-resistant A-172 cells. In addition, the level of selenophosphate synthetase mRNA (SelD), a key intermediate in tRNA(Sec) formation, increased 1.2- to 1.7-fold in A-427 and A-172 cells after pretreatment with sodium selenite. These results indicate that upregulation of GSH-Px activity by sodium selenite in the EPA/DHA sensitive cell line A-427 may be due to an increase in mRNAs for GSH-Px and a precursor important for formation of tRNA(Sec) which is required for incorporation of selenocysteine in GSH-Px during translation. These results demonstrate an important role for GSH-Px in the cellular defence against cytotoxic lipid peroxidation products. Furthermore, measurement of GSH-Px activities in tumour cells may be one useful biochemical predictor for their sensitivities to polyunsaturated fatty acids.
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PMID:Evidence that changes in Se-glutathione peroxidase levels affect the sensitivity of human tumour cell lines to n-3 fatty acids. 936 97

This study was undertaken to evaluate plasma levels of interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha) transforming growth factor-beta (TGF-beta), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF) in 3 pediatric and 14 adult patients receiving radiotherapy for brain tumor. Patients with glioblastoma, astrocytoma, chondrosarcoma, meningioma, schwannoma, and lung adenocarcinoma that had metastasized to the brain were included. Peripheral blood samples were collected before and after treatment with conventional photon and/or proton radiation; samples from healthy volunteers served as controls. Enzyme-linked immunosorbent assays were performed to quantitate the cytokines. Before irradiation, most patients had greater amounts of one or more of the cytokines compared with the mean obtained for control plasma. This was especially striking in patients with chondrosarcoma; the mean values for TGF-beta 1, TNF-alpha, bFGF, and EGF were 1458, 1289, 332, and 92% higher than in healthy subjects, respectively. After irradiation, bFGF and total TGF-beta 1 decreased in the majority of tested subjects. In contrast, IL-1 beta was detected only in pediatric patients (all with astrocytoma) and its levels after radiation were 33 to 67% higher than at pretreatment. EGF was found in four patients; post-treatment values were 125 to 608% higher in three of the individuals. These data show that cytokines are present at elevated concentrations in the blood circulation of patients with certain types of brain tumors and that changes in their levels can be detected after radiotherapy. Further investigations are warranted to determine whether these findings contribute to morbidity or therapeutic outcome.
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PMID:Pilot evaluation of cytokine levels in patients undergoing radiotherapy for brain tumor. 946 45


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