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:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cyclophosphamide and its isomer ifosfamide are cell cycle-nonspecific alkylating agents that undergo bioactivation catalyzed by liver cytochrome P-450 enzymes. The therapeutic efficacy of these oxazaphosphorine anticancer drugs is limited by host toxicity resulting from the systemic distribution of activated drug metabolites formed in the liver. Since tumor cells ordinarily do not have the capacity to activate oxazaphosphorines, we examined whether introduction into tumor cells of a cDNA encoding CYP2B1, a major catalyst of oxazaphosphorine activation, sensitizes the cells to the cytotoxic effects of cyclophosphamide and ifosfamide. Here we show that 9L gliosarcoma cells stably transfected with a cDNA encoding rat CYP2B1 are highly sensitive to cyclophosphamide and ifosfamide cytotoxicity as compared to parental 9L cells or 9L cells transfected with an Escherichia coli beta-galactosidase gene. The CYP2B1 enzyme inhibitor metyrapone protects the CYP2B1-expressing 9L cells from oxazaphosphorine cytotoxicity, demonstrating that the chemosensitivity of these cells is a direct consequence of intracellular prodrug activation. Moreover, CYP2B1-expressing 9L cells potentiate the cytotoxic effects of cyclophosphamide and ifosfamide toward cocultured CYP2B1-negative 9L tumor cells. This "bystander effect" does not require cell-cell contact, and therefore may have the therapeutic advantage of distributing cytotoxic drug metabolites to a wide area within a solid tumor mass. In vivo experiments using Fischer 344 rats implanted s.c. with CYP2B1-expressing 9L tumor cells demonstrated that intratumoral expression of the CYP2B1 gene provides a substantial therapeutic advantage over that provided by liver cytochrome P-450-dependent drug activation alone; cyclophosphamide treatment resulted in complete growth inhibition of CYP2B1-positive tumors, whereas only a modest growth delay effect was obtained with CYP2B1-negative tumors. These studies establish that drug-activating CYP genes may be useful for the development of novel combined chemotherapy/gene therapy strategies for cancer treatment utilizing established cancer chemotherapeutic agents.
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PMID:Intratumoral activation and enhanced chemotherapeutic effect of oxazaphosphorines following cytochrome P-450 gene transfer: development of a combined chemotherapy/cancer gene therapy strategy. 783 28

The efficacy of adenovirus (ADV)-mediated gene therapy to treat brain tumors was tested in a syngeneic glioma model. Tumor cells were transduced in situ with a replication-defective ADV carrying the herpes simplex virus thymidine kinase (HSV-tk) gene controlled by the Rous sarcoma virus promoter. Expression of the HSV-tk gene enables the transduced cell to convert the drug ganciclovir to a form that is cytotoxic to dividing cells. Tumors were generated in Fischer 344 rats by stereotaxic implantation of 9L gliosarcoma cells into the caudate nucleus. Eight days later, the tumors were injected either with the ADV carrying the HSV-tk (ADV-tk) gene or a control ADV vector containing the beta-galactosidase (ADV-beta gal) gene and the rats were treated with either ganciclovir or saline. Tumor size was measured 20 days after implantation of 9L cells or at death. Rats treated with ADV-beta gal and ganciclovir or with ADV-tk and saline had large tumors. No tumors were detected in animals treated with ADV-tk and with ganciclovir at doses > or = 80 mg/kg. An infiltrate of macrophages and lymphocytes at the injection site in animals treated with ADV-tk and ganciclovir indicated an active local immune reaction. In survival studies, all animals treated with ADV-tk and ganciclovir have remained alive longer than 80 and up to 120 days after tumor induction whereas all untreated animals died by 22 days. These results demonstrate that ADV-mediated transfer of HSV-tk to glioma cells in vivo confers sensitivity to ganciclovir, and represents a potential method of treatment of brain tumors.
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PMID:Adenovirus-mediated gene therapy of experimental gliomas. 788 26

Gene transfer with vectors derived from murine retroviruses is restricted to cells which are proliferating and synthesizing DNA at the time of infection. This suggests that retroviral-mediated gene transfer might permit targeting of gene integration into malignant cells in organs composed mainly of quiescent nonproliferating cells, such as in the brain. Accordingly, selective introduction of genes encoding for susceptibility to otherwise nontoxic drugs ("suicide" genes) into proliferating brain tumors may be used to treat this cancer. We investigated the efficacy and dynamics of in vivo transduction of growing brain tumors with the herpes simplex-thymidine kinase gene followed by administration of the antiviral drug ganciclovir. Ganciclovir is phosphorylated by thymidine kinase to toxic triphosphates that interfere with DNA synthesis, resulting in the preferential death of the transduced tumor cells. Rats inoculated with 4 x 10(4) 9L gliosarcoma cells into the frontal lobe were treated 7 days later with an intratumoral stereotaxic injection of murine fibroblasts (NIH 3T3 cells) that were producing a retroviral vector containing the herpes simplex-thymidine kinase gene. Controls received vector producer and nonproducer NIH 3T3 cell lines containing the Escherichia coli lacZ (beta-galactosidase) gene as well as nonproducer NIH 3T3 cells containing the thymidine kinase gene. The animals were rested for 7 days to allow time for in situ transduction of the proliferating tumor cells with the herpes-thymidine kinase retroviral vector. The animals were then treated with ganciclovir, 15 mg/kg i.p. twice a day for 14 days. Gliomas receiving an injection of 3-5 x 10(6) thymidine kinase producer cells regressed completely in 23 of 30 rats given ganciclovir therapy, while 25 of 26 control rats developed large tumors. Intratumoral injection of a lower concentration of thymidine kinase vector producer cells (1.8 x 10(6)) resulted in a lower frequency of tumor regression (5 of 13 rats). To estimate the efficiency of in vivo gene transfer, 9L brain tumors were given injections of 5 x 10(6) beta-galactosidase vector producer cells. 5-Bromo-4-chloro-3-indolyl-beta-D-galactopyranaside staining revealed maximal staining of beta-galactosidase within the tumor 7-14 days after injection of the vector producer cells. In vivo transduction rates in harvested tumors ranged from 10 to 70%. There was no evidence of transduction of the surrounding normal neural tissue. Occasional blood vessel endothelial cells within or adjacent to the tumor were observed to be 5-bromo-4- chloro-3-indolyl-beta-D-galactopyranaside positive.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:In situ retroviral-mediated gene transfer for the treatment of brain tumors in rats. 803 19

We extend use of the lacZ reporter gene for tumor biology. Intracerebral growth of 9L/lacZ, a gliosarcoma cell line that stably expresses lacZ, was evaluated in syngeneic rats. The reporter gene product, Escherichia coli-derived beta-galactosidase (beta-gal), was detected histochemically on tissue sections. This permits visualization of disseminated tumor and, as shown here, facilitates image analysis. We show that the beta-gal marker protein itself can serve as a tumor antigen in appropriate contexts. Quantitative image analysis of tumor areas is used to show that immunization with beta-gal protects against tumor growth. Abnormal beta-gal- areas are easily detected, facilitating study of antigenic modulation. The tumor studied did not escape through this mechanism. All abnormal beta-gal- areas examined were shown to reflect accumulation of inflammatory or reactive cells, not tumor. Taken together, these findings show several ways in which the lacZ reporter gene can be exploited to facilitate quantitative analysis of disseminated tumor growth within the brain. They draw attention to the growing appreciation that tumor antigens need not be cell surface molecules.
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PMID:Exploiting the lacZ reporter gene for quantitative analysis of disseminated tumor growth within the brain: use of the lacZ gene product as a tumor antigen, for evaluation of antigenic modulation, and to facilitate image analysis of tumor growth in situ. 841 43

We evaluated the efficacy of adenoviral-mediated gene therapy of experimental spinal cord tumors and the functional outcome after this treatment. Spinal cord tumors were generated in the thoracic region of the spinal cord in Fischer 344 rats by stereotaxic intramedullary injection of 1 x 10(4) 9L gliosarcoma cells. Seven days after tumor cell injection, a replication-defective adenoviral vector carrying the herpes simplex virus thymidine kinase gene (ADV-tk) or a control adenoviral vector carrying the beta-galactosidase gene (ADV-beta gal) was injected into the tumors. Beginning 12 h later the animals were treated with the antiviral drug ganciclovir (GCV; 50 mg/kg) or saline twice a day for 6 days. The neurological performance of the animals was assessed during and following treatment. Eighteen days after tumor cell injection, all of the control animals had paraplegia and large tumors. In contrast, no tumors were detected in animals treated with ADV-tk and GCV. In long-term studies, two of the 5 animals treated with ADV-tk and GCV remained tumor-free and remained neurologically intact at 6 months whereas all animals in the control groups became paraplegic within 18 days.
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PMID:Adenovirus-mediated gene therapy for experimental spinal cord tumors: tumoricidal efficacy and functional outcome. 859 67

In this study we investigated the intra-arterial delivery of viral and nonviral particles to experimental brain tumors. A herpes simplex virus (HSV) vector and monocrystalline iron oxide nanoparticles (MION) were injected into the internal carotid artery of Fisher 344 rats harboring intracerebral 9L gliosarcomas, using bradykinin to disrupt the blood-tumor barrier. Brain and internal organs were stained both for virus-mediated gene expression and for iron. Quantitative comparisons of gene expression and MION uptake with and without blood-tumor barrier disruption were performed in the center and at the periphery of the tumor mass, as well as in normal brain. In addition, MION distribution was traced in vivo by MR imaging. Delivery of HSV into 9L gliosarcoma cells was greatly enhanced by intra-carotid bradykinin infusion. Virus-mediated expression of the HSV-thymidine kinase (TK) and beta-galactosidase gene products was highest at the tumor periphery as compared to the tumor center. Selective HSV infection of multiple tumor foci was achieved in both hemispheres without affecting normal brain. MION uptake was high at the tumor periphery even without blood-tumor barrier disruption. Bradykinin increased MION uptake predominantly in the center of the tumor with virtually no effect at the periphery. These findings show that selective blood-tumor barrier disruption by bradykinin can be used to enhance HSV-mediated gene delivery to tumor cells in the periphery of brain tumors. A crucial aspect in the treatment of malignant brain tumors is the eradication of tumor cells infiltrating the brain; bradykinin may facilitate access of vectors to these areas by selective disruption of their neovasculature.
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PMID:Selective uptake of viral and monocrystalline particles delivered intra-arterially to experimental brain neoplasms. 866 79

Replication-defective, highly purified retroviral vectors (Retrovector), at titers of 10(8) colony forming units/mL, were prepared that conferred either beta-galactosidase or herpes simplex thymidine kinase (HSV-TK) activity. 9L gliosarcoma cells, transduced efficiently in vitro, were highly sensitive to ganciclovir (GCV). The mean frequency of in situ transduction, measured by flow cytometry of single-cell tumor suspensions isolated from rat brains, was 3.2 +/- 0.6%; similar assessments were made by staining of beta-galactosidase or by immunohistochemistry with anti-HSV-TK. In vitro HSV-TK-transduced and G418-selected 9L-TK gliosarcoma tumors treated with GCV were eradicated in approximately 53% of the animals (10/19) at day 26, however, 89% (17/19) histologically showed < 1% tumor volume. Histologic evaluation at day 26 of animals with established 9L tumors treated with intralesional injection of HSV-TK vector followed by GCV treatment showed that 29% (4/14) had no tumor; 50% (7/14) had < 1% tumor volume. Regression of tumors proceeded over the time since the complete rate was increased at day 60. Neither HSV-TK vector particles nor GCV alone altered the histological profile of 9L tumors, but substantial numbers of CD4+ and CD8+ lymphocytes infiltrated the tumors of animals treated with both. In cured animals, the former tumor bed contained cell debris, immune cells, and fibroblasts and was without damage to adjacent brain. The efficacy of suicide gene therapy for rat gliosarcoma using highly purified virion vectors approaches that of packaging cell lines.
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PMID:Purified herpes simplex thymidine kinase Retrovector particles. I. In vitro characterization, in situ transduction efficiency, and histopathological analyses of gene therapy-treated brain tumors. 908 Jan 21

One approach to improving the specificity of gene therapy involves using radiosensitive promoters to activate gene expression selectively in the radiation field. In this study, we evaluated the ability of irradiation to regulate the transcription of a recombinant replication-defective adenovirus vector, Ad.Egr-1/lacZ, containing the radiation-inducible Egr-1 promoter driving the beta-galactosidase reporter gene in glioma cells. Transcripts of the Egr-1 gene in human and rat glioma cells were induced following irradiation with as little as 2 Gy. This dose was 10-fold less than previously reported, and comparable to doses of irradiation used clinically in standard fractionated radiotherapy for brain tumors. When 9L rat gliosarcoma cells were infected with Ad.Egr-1/lacZ in vitro and exposed to 2 Gy of external beam irradiation, there was a threefold increase in beta-galactosidase expression. Irradiation of intracerebral 9L tumors infected with the Ad.Egr-1/lacZ virus, using either external beam radiotherapy (2 Gy) or the thymidine analog 5-iodo-2'-deoxyuridine radiolabeled with the Auger electron emitter iodine-125 ([125I]IdUrd), also resulted in increased beta-galactosidase activity of the tumor cells. These results indicate that the use of viral vectors containing radiation-inducible promoters represents a novel therapeutic approach that enables gene therapy to be spatially and temporally regulated by ionizing radiation. These findings also support a potential role for radiation-inducible promoters in the treatment of malignant brain tumors.
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PMID:Transgene expression in malignant glioma using a replication-defective adenoviral vector containing the Egr-1 promoter: activation by ionizing radiation or uptake of radioactive iododeoxyuridine. 968 9

Our aim was to test the therapeutic effects of adenovirus-mediated gene therapy in an animal brain tumor model which was obtained by stereotactic injection of 9L gliosarcoma cells into the caudate nucleus of rat brains. Seven days after the implantation of tumor cells, adenovirus vectors bearing the Escherichia coli beta-galactosidase gene (ADVbgal) or the herpes simplex virus thymidine kinase gene (ADVtk) were stereotactically injected into the tumor. Injection of the ADVbgal resulted in the expression of the marker gene in 11 animals. Transfer of the ADVtk was followed, 3 days later, by intraperitoneal injection of ganciclovir (GCV) for 10 days. A control group was treated with saline instead of GCV. We observed a significant regression of the tumors in the rats treated with ADVtk and GCV as compared with control animals. In four cases the tumor completely disappeared after treatment. These results demonstrate the potential efficacy of adenovirus-mediated transfer of the HSVtk gene following by GCV administration for the treatment of glioblastomas.
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PMID:[Gene therapy of cerebral glioblastoma by adenovirus vector. Experimental model in the rat]. 975 39

Recent advances in molecular biology have permitted significant progress toward the treatment of malignant brain tumors using gene transduction methods. Adenovirus vectors have recently been shown to transduce genes successfully into brain tumor cells both in vitro and in vivo. We have investigated the feasibility of gene transduction for brain tumors using adenovirus vectors. To evaluate in vitro transduction rate by adenovirus vectors, rat 9L gliosarcoma cells or human glioblastoma cells were infected with recombinant replication-deficient adenovirus vectors containing the E. coli beta-galactosidase gene (Adex-CALacZ) and stained with X-Gal. We observed a multiplicity of infection (MOI)-dependent rate. Approximately 100% transgene expression was achieved at a MOI of 5 after seven days of incubation. To evaluate transgene expression in a rat brain tumor model, AdexCALacZ was stereotactically injected into established rat 9L brain tumors. Intratumoral injection of AdexCALacZ resulted in high transgene expression in tumor cells. Although injection of AdexCALacZ in the normal basal ganglia resulted in broad and diffuse transduction into endogenous neural cells, direct intratumoral injection resulted in transduction that was relatively restricted to the tumor cells as well as some neighboring normal cells. Transduction rates were relatively elevated at the margin of the tumor. Our results suggest that adenovirus vectors might be a feasible method to transfer therapeutic genes into malignant brain tumors.
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PMID:[Gene transduction for experimental brain tumors using recombinant adenovirus vector]. 975 66


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