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)

Some tumor cells express Ags that are potentially recognizable by T lymphocytes and yet do not elicit significant immune responses. To explore new immunotherapeutic strategies aimed at enhancing the recognition of these tumor-associated Ags (TAA), we developed an experimental mouse model consisting of a lethal clone of the BALB/c tumor line CT26 designated CT26.WT, which was transduced with the lacZ gene encoding beta-galactosidase, to create CT26.CL25. The growth rate and lethality of CT26.CL25 and CT26.WT were virtually identical despite the expression by CT26.CL25 of the model tumor Ag in vivo. A recombinant fowlpox virus (rFPV), which is replication incompetent in mammalian cells, was constructed that expressed the model TAA, beta-galactosidase, under the influence of the 40-kDa vaccinia virus early/late promoter. This recombinant, FPV.bg40k, functioned effectively in vivo as an immunogen, eliciting CD8+ T cells that could effectively lyse CT26.CL25 in vitro. FPV.bg40k protected mice from both subcutaneous and intravenous tumor challenge by CT26.CL25, and most surprisingly, mice bearing established 3-day pulmonary metastasis were found to have significant, Ag-specific decreases in tumor burden and prolonged survival after treatment with the rFPV. These observations constitute the first reported use of rFPV in the prevention and treatment of an experimental cancer and suggest that changing the context in which the immune system encounters a TAA can significantly and therapeutically alter the host immune response against cancer.
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PMID:Active immunotherapy of cancer with a nonreplicating recombinant fowlpox virus encoding a model tumor-associated antigen. 772 21

As a suitable model to study the growth behavior and therapeutic response of drug-resistant and -sensitive cells in three-dimensional coculture we have established multicellular spheroids generated from both cisplatin-sensitive and -resistant cells of a murine fibrosarcoma cell line. A drug resistant clone was derived from the parent cisplatin-sensitive cells by intermittent drug exposure in vitro. As a prerequisite for analysis of differential growth and treatment response of spheroid subpopulations, two efficient methods to discriminate between the two morphologically indistinguishable subpopulations in mixed spheroids were established. In the cisplatin-resistant cell line chosen for the present study, resistance is mainly due to an increased cellular metallothionein content and is therefore associated with increased resistance to CdCl2. Exposure of colonies to high concentrations of CdCl2 thus allowed selective elimination of sensitive colonies. Permanent labeling of either resistant or sensitive cells was achieved by introduction of the Escherichia coli beta-galactosidase marker gene with a retroviral vector system. The transformation of an uncolored galactose derivative by this enzyme into an indigo stain allowed detection of cells carrying and expressing the marker gene. The marker gene and CdCl2 method led to identical results when used simultaneously to distinguish quantitatively between resistant and sensitive colonies grown from plated cells of untreated or irradiated mixed spheroids. The retroviral labeling method was also used successfully in the study of intact spheroids, showing that in 1:1 mixed spheroids, cisplatin-sensitive parent cells accumulate in the spheroid periphery, outgrowing resistant cells and displacing them into the metabolically restricted spheroid center. Only when sensitive and resistant cells are initially mixed at a ratio of 1:9 are the resulting spheroids composed of equal proportions of the 2 cell types throughout 10-20 days after spheroid initiation.
Cancer Res 1995 Jan 15
PMID:Quantitative distinction of cisplatin-sensitive and -resistant mouse fibrosarcoma cells grown in multicell tumor spheroids. 781 71

Among the appealing features of adenoviruses as vectors for transfer of genes into the central nervous system (CNS) are that they are not neurotoxic, they can accommodate the insertion of several large genes, they are not associated with the hazards of insertional mutagenesis, and they can be concentrated to a high-titer preparation. The authors evaluated the feasibility of using adenovirally mediated gene transfer into cultured human glioma cells and in rat models of solid brain tumors and meningeal cancer. Replication-deficient adenoviral vector particles carrying a nuclear-localizing lacZ gene were injected into established 9L cerebral gliomas in Fischer rats. In addition, the adenoviral vector was injected into the subarachnoid space, either simultaneously with intrathecal tumor inoculation or after establishing leptomeningeal cancer. The brains and spinal cords were removed at various intervals for histochemical evaluation for beta-galactosidase activity using X-Gal staining. Additional rats received a stereotactic intracerebral injection of the vector into normal brain. No clinical abnormalities were observed in the injected rats. Injection of the adenoviral vector into normal brain resulted in diffuse transduction of astrocytes, microglia, neurons, and endothelial cells at the injection site. Injection of a high-concentration vector preparation into cerebral gliomas resulted in effective tumor transduction. Intrathecal injection of the vector in rats with meningeal cancer resulted in transduction of the infiltrating tumor in the subarachnoid space when injections were given simultaneously with, or 7 days after, tumor inoculation. Transduction rates of both solid and leptomeningeal tumors correlated with the number of injected particles. These results suggest that adenoviral vectors can efficiently transduce solid brain tumors and that the vectors survive in the cerebrospinal fluid for a sufficient period of time to allow leptomeningeal tumor transduction. Adenoviral vector should be evaluated for its potential use in therapeutic gene transfer approaches in malignancies of the CNS.
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PMID:Adenovirally mediated gene transfer into experimental solid brain tumors and leptomeningeal cancer cells. 781 37

The mucin-type carbohydrate Tn cryptantigen (GalNAc alpha 1-O-Ser/Thr, where GalNAc is N-acetyl-D-galactosamine) is expressed in many carcinomas, in haemopoietic disorders including the Tn syndrome, and on human immunodeficiency virus (HIV) coat glycoproteins, but is not expressed on normal, differentiated cells because of the expression of a Tn-processing galactosyltransferase. Using Jurkat T leukaemic cells which express high levels of Tn antigen due to deficient Tn galactosylation, we have established the Tn antigen-mediated gene transfer and demonstrate the considerable efficiency of this approach. We used poly(L-lysine) conjugates of the monoclonal antibody 1E3 directed against the Tn antigen to deliver the luciferase and beta-galactosidase reporter genes to Jurkat cells by receptor-mediated endocytosis. Addition of unconjugated 1E3 reduced transfection efficiency in a concentration-dependent manner and incubation with free GalNAc abolished DNA transfer completely, indicating that gene delivery is indeed mediated by the Tn antigen. Pre-treatment of Jurkat cells with Vibrio cholerae sialidase, which uncovers additional Tn antigens, resulted in an improvement of gene transfection. Both human and chicken adenovirus particles attached to the DNA/polylysine complex strongly augmented transgene expression. When the beta-galactosidase (lacZ) gene was delivered to Jurkat cells by Tn-mediated endocytosis, up to 60% of the cells were positive in the cytochemical stain using 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal) as a chromogenic substrate. The efficiency of the transferrin receptor-mediated DNA uptake into Jurkat cells was comparatively low, although these cells were shown to express considerable amounts of transferrin receptor. We show here that a mucin-type carbohydrate antigen mediates highly efficient DNA uptake by endocytosis into Jurkat T cells. This method represents a 50-fold improvement of Jurkat cell transfection efficiency over other physical gene transfer techniques. Specific gene delivery to primary cancer cells exhibiting Tn epitopes may especially be desirable in immunotherapy protocols.
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PMID:Carbohydrate receptor-mediated gene transfer to human T leukaemic cells. 782 4

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.
Cancer Res 1995 Feb 01
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 immunohistochemical reactivity of a second generation murine monoclonal antibody (LU-BCRU-G7), raised against a novel fucosylated glycoprotein of M(r) 2300,000, has shown a significant association with prognosis of early stage carcinomas. Staining was observed in 72% of the 190 breast carcinomas tested. No relationship with steroid receptor status, stage or node status was found. An association with grade was observed (chi 2 7.83, 2 degrees of freedom, P = 0.02) only when the negative cut-off level was raised from < 10% cells staining to < 25%. Antibody reactivity was always cytoplasmic. Immunoblotting shows the antibody is reactive with a component of M(r) 230,000 not detected by HMFG 2. A significant association was found between lack of reactivity and improved disease-free interval (0.005 > P > 0.001) and survival (0.02 > P > 0.01). Subdivision of cases on the basis of node status showed that staining could refine survival data. A decreased reactivity of LU-BCRU-G7 was observed after pretreatment with beta-galactosidase but not a sialidase or beta-N-acetylhexosaminodase indicating that non-reducing terminal galactose residues in beta 1-3 or beta 1-4 linkages may be involved in the antibody binding site. This approach has identified a useful and novel prognostic marker in early stage human breast carcinoma.
Eur J Cancer 1994
PMID:Prognostic value of a breast cancer-associated glycoprotein detected by monoclonal antibody LU-BCRU-G7. 794 64

The interaction of normal (CHO-K1) and multidrug-resistant (Adrr) Chinese hamster ovary cells was examined in mixed monolayer and spheroid culture. In order to assess the individual response of the two cell types in mixed culture, CHO-K1 was genetically marked by transfection with a bacterial beta-galactosidase gene. The enzyme product can be detected histochemically and allows identification of the marked cell line, designated CHO-K1-BG. Following administration of doxorubicin or mitozantrone, there was a large difference in the clonogenic survival of CHO-K1-BG and Adrr, whereas the overall survival of a 50:50 mixture of the two cell lines had intermediate values. When the survival of marked and unmarked colonies from mixed culture was assessed separately, there was no detectable alteration in chemosensitivity. We have found no evidence for interaction of sensitive and multidrug-resistant cells in this system.
Br J Cancer 1994 Nov
PMID:The use of genetic marking to assess the interaction of sensitive and multidrug-resistant cells in mixed culture. 794 83

The human monoclonal antibody (HuMAb) L92 reacts to an M(r) 43,000 protein associated with human melanoma. To identify the gene encoding its antigenic epitope, a complementary DNA expression library constructed from the human melanoma cell line UCLASO M14 was screened with HuMAb L92. DNA sequence analysis of the isolated clone revealed that the immunoreactive peptide was composed of 10 amino acids (QDLT-MKYQIF). The peptide was expressed in Escherichia coli with beta-galactosidase as a fused protein. There is no homology between the cloned sequence and other reported DNA sequences. Western blot analysis showed that the fused protein had specific binding to HuMAb L92. An antigen-encoding peptide with 10 amino acids was synthesized and tested for its immunoreactivity in vitro. HuMAb L92 reacted specifically to the 10-amino acid peptide in both an antibody-binding inhibition to the M(r) 43,000 protein and a solid-phase enzyme-linked immunosorbent assay. Using several truncated fusion proteins, we found the minimum number of amino acids required for the antibody binding to be 4 (KYQI). These results suggest that the identified peptide sequence encodes the antigenic epitope of the M(r) 43,000 protein.
Cancer Res 1994 Jul 01
PMID:Human monoclonal antibody identified an immunoreactive tetrapeptide sequence (Lys-Tyr-Gln-Ile) in M(r) 43,000 protein of human melanoma. 801 74

We studied the antimutagenic effects of urine on the SOS-inducing activity of mutagenic substances by using a novel test system (umu-test) for detecting DNA damaging agents, which uses a new tester strain (Salmonella typhimurium TA1535/pSK1002). The SOS-inducing activity of chemicals was detected in terms of the level of umu operon expression by measuring beta-galactosidase activity. We first examined the effects of various amounts of urine on SOS responses caused by mitomycin C (MMC). As a result, the urine suppressed beta-galactosidase activity of MMC dose-dependently. A urine concentration of 50 microliters/ml in the medium also suppressed 89.9% of SOS response induced by 0.1 microgram/ml of PEP, 75.6% of that induced by 0.02 microgram/ml of AF2 and 60.9% of that induced by 0.1 microgram/ml of AFB1. In addition, a urine concentration of 50 microliters/ml in the medium also suppressed 85.6% of SOS response by 5 J/m2 of UV irradiation. The observed suppression seemed to be directly related to the SOS responses at a cellular level, rather than to interaction between urine and mutagens, because the urine suppressed SOS responses induced not only by various mutagens but also by UV irradiation. These results suggest that urine works as a strong antimutagen against UV and chemical substances.
Cancer Lett 1994 Jun 15
PMID:Suppressive effects of urine on the SOS responses induced by UV and chemical mutagens. 801 82

Although in vivo models utilizing endogenous reporter genes have been exploited for many years, the use of reporter transgenes to dissect biological issues in transgenic animals has been a relatively recent development. These transgenes are often, but not always, of prokaryotic origin and encode products not normally associated with eukaryotic cells and tissues. Some encode enzymes whose activities are detected in cell and tissue homogenates, whereas others encode products that can be detected in situ at the single cell level. Reporter genes have been used to identify regulatory elements that are important for tissue-specific gene expression or for development; they have been used to produce in vivo models of cancer; they have been employed for the study of in vivo mutagenesis; and they have been used as a tool in lineage analysis and for marking cells in transplantation experiments. The most commonly used in situ reporter gene is lacZ, which encodes a bacterial beta-galactosidase, a sensitive histochemical marker. Although it has been used with striking success in cultured cells and in transgenic mouse embryos, its postnatal in vivo expression has been unreliable and disappointing. Nevertheless, the ability to express reporter genes in transgenic mice has been an invaluable resource, providing insights into in vivo biological mechanisms. The development of new in vivo models, such as those in which expression of transgenes can be activated or repressed, should produce transgenic animal systems that extend our capacity to address heretofore unresolved biological questions.
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PMID:Reporter genes in transgenic mice. 802 96


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