Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Current gene therapy technology is limited by the paucity of methodology for determining the location and magnitude of therapeutic transgene expression in vivo. We describe and validate a paradigm for monitoring therapeutic transgene expression by noninvasive imaging of the herpes simplex virus type 1 thymidine kinase (HSV-1-tk) marker gene expression. To test proportional coexpression of therapeutic and marker genes, a model fusion gene comprising green fluorescent protein (gfp) and HSV-1-tk genes was generated (tkgfp gene) and assessed for the functional coexpression of the gene product, TKGFP fusion protein, in rat 9L gliosarcoma, RG2 glioma, and W256 carcinoma cells. Analysis of the TKGFP protein demonstrated that it can serve as a therapeutic gene by rendering tkgfp transduced cells sensitive to ganciclovir or as a screening marker useful for identifying transduced cells by fluorescence microscopy or fluorescence-activated cell sorting (FACS). TK and GFP activities in the TKGFP fusion protein were similar to corresponding wild-type proteins and accumulation of the HSV-1-tk-specific radiolabeled substrate, 2'-fluoro-2'-deoxy-1beta-D-arabinofuranosyl-5-iodo-uracil (FIAU), in stability transduced clones correlated with gfp-fluorescence intensity over a wide range of expression levels. The tkgfp fusion gene itself may be useful in developing novel cancer gene therapy approaches. Valuable information about the efficiency of gene transfer and expression could be obtained by non-invasive imaging of tkgfp expression with FIAU and clinical imaging devices (gamma camera, positron-emission tomography [PET], single photon emission computed tomography [SPECT]), and/or direct visualization of gfp expression in situ by fluorescence microscopy or endoscopy.
 ...
PMID:Functional coexpression of HSV-1 thymidine kinase and green fluorescent protein: implications for noninvasive imaging of transgene expression. 1093 50

N,N'-bis(2-hydroxyethyl)-N-nitrosourea (BCNU) is a commonly used agent for treatment of malignant gliomas. The mechanisms of cell death and the role of Bcl-2 and Bax in a BCNU-treated rat glioma cell line were investigated. Our results indicate that apoptosis occurs only at a high concentration of BCNU with elevated levels of Bax and a reversed ratio of Bax/Bcl-2. Overexpression of Bax delivered by a herpes simplex viral vector in combination with BCNU chemotherapy enhanced the efficacy of BCNU in a rat glioma model. These findings suggest that conventional treatment with BCNU may be combined with gene therapy that delivers a bax gene into the glioma cells to achieve a high level of Bax, facilitating BCNU-induced cytotoxicity.
 ...
PMID:Bax expressed from a herpes viral vector enhances the efficacy of N,N'-bis(2-hydroxyethyl)-N-nitrosourea treatment in a rat glioma model. 1097 71

Suicide gene therapy utilizing the herpes simplex thymidine kinase (HSVtk) / ganciclovir (GCV) system has been performed to kill cancer cells. However, the low transduction efficiency of HSVtk gene into cancer cells critically limits its efficacy in cancer treatment in clinical situations. To improve delivery of the HSVtk gene into cancer cells, we transduced U-87MG and U-373MG glioma cells with adenovirus (Adv) vectors with a fiber mutant, F / K20, which has a stretch of 20 lysine residues added at the C-terminus of the fiber, for the HSVtk gene (Adv-TK-F / K20), and compared the cytopathic effect of Adv-TK-F / K20 with that of the Adv for HSVtk with wild-type fiber (Adv-TK). The cytopathic effect of Adv-TK-F / K20 in U-87MG and U-373MG cells was approximately 140 and 40 times, respectively, stronger than that of Adv-TK. At the same multiplicity of infection (MOI) in each cell line, Adv-TK-F / K20 induced a higher degree of apoptosis (U-87MG, 35%; U-373MG, 77%) than Adv-TK (U-87MG, 0.11%; U-373MG, 27%) in U-87MG (MOI 0.03) and U-373MG cells (MOI 0.1). Cleavage of poly(ADP-ribose)polymerase (PARP) was more marked in the cells that were infected with Adv-TK-F / K20 than in cells that were infected with Adv-TK. These results indicate that gene therapy utilizing Adv-TK-F / K20 may be a promising therapeutic modality for the treatment of gliomas.
 ...
PMID:Transduction of a fiber-mutant adenovirus for the HSVtk gene highly augments the cytopathic effect towards gliomas. 1105 Apr 74

A number of different viral vectors have been used for gene therapy of tumors, with many more under construction, ultimately designed to improve tumor targeting and transduction efficiency. It has become apparent that insufficient viral delivery can be a key limitation to treatment efficacy. We have studied the in vivo mass distribution of a herpes simplex virus type 1 (HSV) vector, hrR3, by radiolabeling it with 111In-oxine. The virus was administered to intracerebral 9L glioma bearing Fisher (F-344) rats by intracarotid and intratumoral injection. The blood half-life of the virus was 1 min (fast component, 10% contribution) and 180 min (slow component, 90% contribution). Approximately 20% of activity had been excreted by 24 h. With intracarotid injection, the total amount of virus that accumulated in tumor was 0.10+/-0.07% of the injected dose (ID)/g at 1 h and 0.19+/-0.01% ID/g at 24 h. By comparison, co-injection of RMP-7, a synthetic bradykinin analog, with the virus, resulted in slightly increased tumor delivery of 0.17+/-0.10% ID/g (P 0.05) at 1 h. The 1 h organ distribution after intra-arterial injection (%ID/organ) was as follows: liver 273+/-2.86%, lung 2.10+/-0.68% and kidney 1.78+/-1.60% with lesser amounts in other organs. When virus was injected directly into the tumor, 71% of virus remained in tumor at 24 h (590+/-212 %ID/g, consistent with the small tumor mass containing most of the virus) with the following distribution regions: tumor > border zone > normal brain (99:40: 1). These studies are the first quantitative mass distribution studies of HSV vectors in an experimental brain tumor model. Localization and quantitation of viral accumulation in vivo will enable detailed analysis of viral and organ interactions critical for advancing the therapeutic use of vectors.
 ...
PMID:Quantitation of HSV mass distribution in a rodent brain tumor model. 1108 73

Herpes simplex virus thymidine kinase (HSV tk) gene therapy combined with ganciclovir (GCV) medication is a potential new method for the treatment of malignant glioma. We have used both retrovirus-packaging cells (PA317/tk) and adenoviruses (Adv/tk) for gene therapy for malignant glioma. Retrovirus-packaging cells were used for eight tumors in seven patients and adenoviruses were used for seven tumors in seven patients. As a control group, seven tumors in seven patients were transduced with lacZ marker gene 4-5 days before tumor resection. Safety and efficacy of the gene therapy were studied with clinical evaluation, blood and urine samples, MRI follow-up, and survival of the patients. Four patients with adenovirus injections had a significant increase in anti-adenovirus antibodies and two of them had a short-term fever reaction. Frequency of epileptic seizures increased in two patients. No other adverse events possibly related to gene therapy were detected. In the retrovirus group, all treated gliomas showed progression by MRI at the 3-month time point, whereas three of the seven patients treated with Adv/tk remained stable (p < 0.05). Mean survival times for retrovirus, adenovirus, and control groups were 7.4, 15.0, and 8. 3 months, respectively. The difference in the survival times between the adenovirus and retrovirus groups was significant (p < 0.012). It is concluded that HSV tk gene therapy is safe and well tolerated. On the basis of these results further trials are justified, especially with adenovirus vectors.
 ...
PMID:Thymidine kinase gene therapy for human malignant glioma, using replication-deficient retroviruses or adenoviruses. 1108 77

"Gene therapy" can be defined as the transfer of genetic material into a patient's cells for therapeutic purposes. To date, a diverse and creative assortment of treatment strategies utilizing gene therapy have been devised, including gene transfer for modulating the immune system, enzyme prodrug ("suicide gene") therapy, oncolytic therapy, replacement/therapeutic gene transfer, and antisense therapy. For malignant glioma, gene-directed prodrug therapy using the herpes simplex virus thymidine kinase gene was the first gene therapy attempted clinically. A variety of different strategies have now been pursued experimentally and in clinical trials. Although, to date, gene therapy for brain tumors has been found to be reasonably safe, concerns still exist regarding issues related to viral delivery, transduction efficiency, potential pathologic response of the brain, and treatment efficacy. Improved viral vectors are being sought, and potential use of gene therapy in combination with other treatments is being investigated.
 ...
PMID:Gene therapy for brain tumors. 1112 79

G207 is a multimutated, conditionally replicating herpes simplex virus type 1 (HSV-1) that is currently in clinical trial for patients with malignant glioma. G207 exhibits an efficient oncolytic activity in tumor cells, yet minimal toxicity in normal tissue when injected into the brains of HSV-susceptible mice or nonhuman primates. In this study, we evaluated the shedding and biodistribution of clinical-grade G207 after intracerebral inoculation (3 x 10(7) pfu) in four New World owl monkeys (Aotus nancymae). Using PCR analyses and viral cultures, neither infectious virus nor viral DNA was detected from tear, saliva, or vaginal secretion samples at any time point up to 1 month postinoculation. Analyses of tissues obtained at necropsy at 1 month from two of the four monkeys, plus one monkey inoculated with laboratory-grade G207 (10(9) pfu) 2 years earlier, showed the distribution of G207 DNA restricted to the brain, although infectious virus was not isolated. Histopathology revealed normal brain tissues including the sites of inoculation. A measurable increase of serum anti-HSV antibody titer was observed in all monkeys, as early as 21 days postinoculation. The results ascertain the safety of G207 in the brain and indicate that strict biohazard management may not be required for G207-treated patients.
 ...
PMID:Viral shedding and biodistribution of G207, a multimutated, conditionally replicating herpes simplex virus type 1, after intracerebral inoculation in aotus. 1112 59

To clarify the mechanism of interleukin (IL)-6 elevation in the cerebrospinal fluid of viral meningitis and/or encephalitis patients, we investigated how herpes simplex virus type 1 (HSV1)-infection enhances IL-6 production in human glioma cells (the U373MG and T98G cells). Although human glioma cells did not show enhanced IL-6 production by direct HSV1-infection, the cell-free supernatant from HSV1-stimulated mononuclear cells (MNC) culture and lipopolysaccharide, as a positive control, markedly elevated IL-6 production at both mRNA and polypeptide levels. Ultra violet-irradiated HSV1 induced the secretion of the IL-6 inducing factor(s) from MNC, whereas heat-inactivated HSV1 did not show this activity. This finding indicated that the adsorption of virus on the surface of MNC may be sufficient for induction of secretion. The supernatant from the culture of HSV1-stimulated MNC contained detectable amounts of IL-1beta, tumor necrosis factor (TNF) alpha, interferon (IFN) gamma and IL-6, and its IL-6-inducing activity was inhibited only by anti-IL-1beta antibodies. Moreover, recombinant IL-1beta markedly enhanced IL-6 production in glioma cells with a concomitant elevation of its mRNA level. Taken together, the results suggest that in HSV1-infection of the CNS, enhancement of IL-6 production in glial cells is mediated not by direct infection to glial cells but rather by IL-1beta released from HSV1-stimulated MNC. These findings may help elucidate the mechanisms underlying cerebro-parenchymal inflammatory progression and repair in herpes simplex encephalitis.
 ...
PMID:Direct and mononuclear cell mediated effects on interleukin 6 production by glioma cells in infection with herpes simplex virus type 1. 1117 66

Radiolabelled ganciclovir analogues have shown promise as imaging agents to detect herpes simplex virus thymidine kinase (HSVtk) expression. This study evaluated the use of positron emission tomography (PET) imaging with 9-[(3-[18F]fluoro-1-hydroxy-2-propoxy)methyl]guanine ([18F]FHPG) to assess gene transfer into tumours. HSVtk-positive and HSVtk-negative cell lines were first treated in vitro with [18F]FHPG. To assess the efficacy of PET in detecting HSVtk expression following in vivo gene transfer, mice were injected intravenously with an adenovirus encoding HSVtk (Ad.HSVtk), a control vector (Ad.Bgl2) or saline. Subcutaneous human glioma xenografts were grown in mice and treated by direct injection of Ad.HSVtk or Ad.Bgl2. Imaging was performed 48 h after transduction. Similar experiments were performed using Fischer rats implanted with syngeneic tumours. The presence of the HSVtk protein was confirmed by immunohistochemistry. Biodistribution studies were also obtained in 14 naive mice. In vitro studies showed high and specific uptake of [18F]FHPG in HSVtk-positive cell lines, with an uptake ratio of up to 27:1. PET imaging and direct counting of major organs demonstrated HSVtk-specific tracer retention. In mice, HSVtk-positive tumours retained 3.4% dose/gram as compared to 0.6% for control tumours (P=0.03). They were clearly seen on the PET images as early as 100 min post injection. Similar results were obtained with syngeneic rat tumours. Biodistribution studies demonstrated the rapid distribution and clearance of the tracer in all major organs. Our results demonstrate that PET imaging of HSVtk gene transfer to tumours is feasible and is highly specific for HSVtk expression.
 ...
PMID:Imaging in vivo herpes simplex virus thymidine kinase gene transfer to tumour-bearing rodents using positron emission tomography and. 1120 52

Cancer suicide gene therapy affords the prospect of using the most optimal genes available because the source of the therapeutic gene is often irrelevant. Currently, there are numerous preclinical and clinical trials to develop tumor ablative therapies that use viral, yeast, or bacterial genes. One such gene, the herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) is widely used as a suicide gene in combination with ganciclovir. In the study reported here, a restricted set of random sequences (semi-random) was introduced into the active site of HSV-1 TK, and the resulting variants were selected on the basis of their ability to confer increased ganciclovir or acyclovir sensitivity to Escherichia coli. Sequence analysis demonstrated that functional mutants contained three to five amino acid substitutions that are unique and novel combinations. On the basis of enzyme assay results, three mutants were identified for further analysis in vitro. These three mutants conferred substantial increased sensitivity to both ganciclovir and acyclovir when compared with IC50s of wild-type TK expressing rat C6 glioma cells. One mutant, SR39, was further evaluated in a xenograft tumor model in nude mice. Expression of SR39 in tumors was shown to prevent tumor growth at prodrug dosages that did not affect wild-type HSV-1 TK-expressing tumors. The use of any of these mutants as a suicide gene should provide a more effective and safer alternative to wild-type TK, because lower, less immunosuppressive doses of ganciclovir will be necessary for tumor ablation, and the use of acyclovir may now be possible.
 ...
PMID:Herpes simplex virus-1 thymidine kinase mutants created by semi-random sequence mutagenesis improve prodrug-mediated tumor cell killing. 1130 82


<< Previous 1 2 3 4 5 6 7 8 9 10