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)

During tumor progression, micrometastases at their earliest stages have been difficult to analyze qualitatively or quantitatively because of a lack of suitably sensitive markers to discriminate small numbers of tumor cells from normal tissue cell populations. To overcome this problem, the Escherichia coli beta-galactosidase (lacZ) gene was introduced into human EJ Ha-ras oncogene-transfected BALB/c 3T3 cells with subsequent injection of transfected cells into athymic nude mice. Using a chromogenic substrate (5-bromo-4-chloro-3-indoyl-beta-D-galactopyranoside), the lacZ-bearing tumor cells at primary tumor sites as well as at secondary organs stain intensely blue and can be easily distinguished from the host tissue cells hours, days, or weeks postinjection. Staining of lacZ-bearing tumor cells is specific and extremely sensitive in detecting micrometastatic foci in lungs and other organs, including brain and kidney for the first time. Stable integration of the lacZ and ras genes into cultured cells and subsequent tumor cells was verified by Southern blot analyses. The lacZ gene appears to be a stable marker during tumor progression in vivo based both on phenotypic (5-bromo-4-chloro-3-indoyl-beta-D-galactopyranoside staining) and on genotypic (Southern blot analysis) evidence. Furthermore, 5-bromo-4-chloro-3-indoyl-beta-D-galactopyranoside staining of tumor cells can also be used together with alkaline phosphatase staining relatively specific for endothelial cells to relate the topographies of metastatic cells and host blood vessels in embedded sections. By using the lacZ gene as a sensitive quantitative marker, analyses of micrometastasis development in the lung indicate that the ras oncogene contributes to the metastatic phenotype in this EJ Ha-ras model system, although further genetic and/or phenotypic alterations appear to be necessary for long-term growth and development into overt metastases. These findings demonstrate the effectiveness and sensitivity of the bacterial lacZ gene as a phenotypic marker in tumor progression studies, providing both a qualitative and a quantitative tool in virtually any tumor system for examining micrometastasis formation in target organs and the relationship of tumor cells to host organ microenvironments.
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PMID:Bacterial lacZ gene as a highly sensitive marker to detect micrometastasis formation during tumor progression. 218 31

We report on an in vivo delivery system that attenuates the growth, in nude mice, of a malignant human breast cancer cell line containing a p53 mutation. Nude mice, inoculated with breast carcinoma cells, were injected every 10-12 days with a liposome-p53 complex via the tail vein. A significant reduction of greater than 60% in primary tumor volume was observed as compared to the control groups. Furthermore, when individual growth patterns of the tumors were assessed, we found that primary tumor size regressed in the majority of p53-treated animals (8/15), whereas only one tumor in the control groups (1/22) regressed. The eight tumors that regressed with the liposome-p53 complex showed no evidence of relapse for 1 month after the cessation of treatment. We also determined that the administration of the liposome-p53 complex reduced the incidence of metastases. The MDA-MB-435 tumor cells, transduced with the lacZ gene, facilitated quantitation of beta-galactosidase activity and tumor burden in the lungs. The number of metastatic cells in the lung was significantly lower in the p53-treated group (0.53 +/- 0.43 x 10(6), p < 0.01) than in either the vector-treated (8.1 +/- 3.7 x 10(6)) or untreated control groups (15.8 +/- 5.9 x 10(6)). Thus, systemic administration of the liposome-p53 complex reduced not only the size of the primary tumors but, more importantly, prevented the relapse and metastases of these tumors.
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PMID:Systemic gene therapy with p53 reduces growth and metastases of a malignant human breast cancer in nude mice. 761 97

Factors that influence early events of primary tumor development have been cumbersome to evaluate because of the need to either wait for tumor palpability after experimental manipulation or use of radiolabel to evaluate cell clearance. To facilitate these and similar analyses of cells in vivo, new methods are described that utilize histochemical marker genes to quantitate tumor cell number in a target tissue through the use of luminescent, enzymatic assays for these gene products. 3T3 Cells transfected with either human placental alkaline phosphatase or bacterial lacZ genes were injected subcutaneously into athymic nude mice. Using luminescent substrates designed for marker gene enzymes, extracts from homogenized tumor cell-bearing skins were assayed for the corresponding marker enzyme activities, which were optimized for recovery from skin extracts and correlated to cell number. The homogenization buffer used for these assays was designed to accommodate the optimal and simultaneous recovery of cytosolic beta-galactosidase and membrane-linked alkaline phosphatase from the skin, as well as from cultured cells. These assays provide an inexpensive, sensitive method for quantitatively monitoring the fate of cells genetically tagged with marker genes in various in vivo environments.
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PMID:Quantitation of two histochemical markers in the same extract using chemiluminescent substrates. 781 4

Invasion-inhibiting factor 2 (IIF-2) and its albumin conjugate have been reported to inhibit spontaneous metastasis of highly metastatic cancer cells with no effect on primary tumor growth. To confirm the inhibitory effects of the IIF-2 conjugate on tumor invasion and spontaneous metastasis, we administered the conjugate intra-peritoneally (i.p.) to female nude mice bearing transplanted tumors with MKL-4 cells, which are MCF-7 human breast cancer cells cotransfected with fibroblast growth factor 4 and lacZ. Neither 10 nor 20 mg/kg doses of the conjugate caused any inhibition of primary tumor growth, but 20 mg/kg significantly inhibited tumor invasion and spontaneous metastasis. Tumor invasion was measured by a novel computer-assisted image analysis. Spontaneous microscopic metastases into lymph nodes and distant organs were measured by whole organ staining for beta-galactosidase activity and observed with a dissecting microscope. The dose of 10 mg/kg significantly inhibited tumor invasion but not metastasis. Interestingly, the number of factor VIII-positive microvessels in the tumors was not reduced by treatment at either dose level. These findings suggest that the anti-invasive effect of the IIF-2 conjugate may reduce both lymphatic and hematogenous metastases in this MKL-4 metastasis model without affecting angiogenesis.
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PMID:Invasion-inhibiting factor 2-albumin conjugate inhibits invasion and spontaneous metastasis of MKL-4 human breast cancer cells transplanted into female nude mice. 860 32

The efficient genetic modification of solid tumors in situ to stimulate therapeutic immune responses against them is currently under active investigation, but is not yet possible using existing gene transfer technologies. Thus, ex vivo/in vivo vaccination strategies have been proposed in which the patient's tumor is surgically excised, single cell suspensions are prepared, the therapeutic genes are introduced and then the gene-modified cells, after being gamma-irradiated, are injected back into the patient. However, even with high-efficiency gene delivery systems, this is a labor-intensive process. Moreover, it is often difficult to obtain sufficient numbers of gene-modified primary tumor cells during short-term culturing. On the other hand, extended in vitro passaging of primary tumor explants may alter their immunophenotypic properties. One approach to overcome these limitations would be to design universal vaccines consisting of standardized gene-transduced neoplastic cell lines or mixtures of gene-transduced cell lines to be combined with autologous tumor samples if available. Melanoma, which is notable for being one of the most immunogenic human malignancies, represents a cancer where shared tumor-associated antigens have been identified. We developed and analyzed several different retroviral vectors for their ability to stably express exogenous genes at high levels in a panel of melanoma cell lines. All vectors contained a reporter gene (nlslacZ) encoding beta-galactosidase with a nuclear localization signal and the neomycin phosphotransferase (neo) gene as selectable marker. One vector, DCCMV, which carried a bicistronic nlslacZ-neo transcriptional unit under the control of the human cytomegalovirus immediate-early promoter in the U3 region of its 3' LTR, was found to perform consistently better than the other vectors. The DCCMV vector, which is an extreme example of the double-copy class of retroviral vectors, was subsequently used to generate melanoma cell lines constitutively secreting human interleukin-6 or a soluble form of the human interleukin-6 receptor for potential use in a phase II clinical vaccine trial for the treatment of melanoma patients. The DCCMV vector design may also be useful in gene therapy applications where the intent is to implant polymer-encapsulated cell lines genetically engineered to stably express high levels of bioactive proteins.
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PMID:Double-copy bicistronic retroviral vector platform for gene therapy and tissue engineering: application to melanoma vaccine development. 941 12

More than 50 genes have been identified in Drosophila by loss-of-function mutations that lead to overgrowth of specific tissues. Loss-of-function mutations in the lethal giant larvae, discs large, or brain tumor genes cause neoplastic overgrowth of larval brains and imaginal discs. In the present study, the growth and metastatic potential of tumors resulting from mutations in these genes were quantified. Overgrown brains and imaginal discs were transplanted into adults and beta-galactosidase accumulation was used as a marker to identify donor cells. Mutations in these three genes generated tumors with similar metastatic patterns. For brain tumors, the metastatic index (a measure we defined as the fraction of hosts that acquired secondary tumors normalized for the amount of primary tumor growth) of each of the three mutants was similar. Analysis of cell proliferation in mutant brains suggests that the tumors arise from a population of several hundred cells which represent only 1-2% of the cells in third instar larval brains. For imaginal disc tumors from lethal giant larvae and brain tumor mutants, it is shown for the first time that they can be metastatic and invasive. Primary imaginal disc tumors from lethal giant larvae and brain tumor mutants formed secondary tumors in 43 and 53% of the hosts, respectively, although the secondary tumors were, in general, smaller than the secondary tumors derived from primary brain tumors.
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PMID:Growth, metastasis, and invasiveness of Drosophila tumors caused by mutations in specific tumor suppressor genes. 951 May 49

To explore the potential of recombinant vectors based on recombinant adeno-associated virus (rAAV) for cancer vaccination, we investigated the transduction efficiency of rAAV into cancer cells ex vivo. Infection of human epithelial cancer cell lines with rAAV carrying reporter genes encoding beta-galactosidase (rAAV/LacZ) or luciferase (rAAV/Luc) resulted in high levels of reporter gene expression (>90% positive cells). In marked contrast, rAAV poorly transduced all murine tumor cell lines, as well as human hematopoietic cell lines. Either irradiation or adenovirus infection of tumor cells prior to rAAV infection induced a 10- to 100-fold increase of reporter gene expression. To determine the transduction efficiency of rAAV into primary cancer cells, freshly isolated, irradiated tumor cells from malignant melanoma and ovarian carcinoma patients were infected with rAAV/Luc, resulting in up to 6.9-fold higher levels of gene expression than in a HeLa tumor cell line. Time course experiments with freshly isolated tumor cells infected with rAAV/Luc showed maximal levels of luciferase expression between days 3 and 9 posttransduction. Simultaneous infection of primary tumor cells with up to three rAAV vectors containing genes encoding the immunostimulatory proteins B7-2 (CD86), p35 subunit of IL-12, and p40 subunit of IL-12 resulted in high expression of B7-2 in more than 90% of the tumor cells and in the secretion of high levels of IL-12. Taken together, our results demonstrate that rAAV efficiently transduces freshly isolated human, epithelial tumor cells and might therefore be a potent tool to produce improved, gene-modified cancer vaccines.
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PMID:Recombinant adeno-associated virus for the generation of autologous, gene-modified tumor vaccines: evidence for a high transduction efficiency into primary epithelial cancer cells. 960 16

Replication-deficient adenovirus vectors are efficient vehicles for delivering therapeutic genes into mammalian cells. However, the high doses required to produce effective gene transfer in vivo can also cause unwanted cellular toxicity. To improve replication-deficient adenovirus transgene expression while minimizing adverse reactions, we have tested polycationic compounds for their ability to enhance adenovirus adsorption. We demonstrate increased transgene expression after mixing adenovirus preparations with polycations, cationic lipids, and CaCl2 prior to transduction in vitro. An E1-deleted adenovirus vector was admixed with various polycations, and beta-galactosidase (beta-gal) activity was evaluated. The optimal polycation concentrations for augmenting adenovirus-mediated gene transfer were 5-10 microg/mL polybrene, 400 microg/mL protamine sulfate, 10 microg/mL N-(1-[2,3-dioleoyloxy]propyl)-N,N,N-trimethylammonium methylsulfate (DOTAP), 2.5 microg/mL Lipofectamine, and 62.5 mM CaCl2. Polycations enhanced beta-gal expression in three of six established cell lines. Similar results were obtained using primary tumor cell cultures, where beta-gal expression was increased 1.5- to 10.7-fold (mean = 3.6) by polybrene, 1.8- to 7.5-fold (mean = 3.4) by DOTAP, and 2.3- to 10.4-fold (mean = 4.8) by protamine sulfate. Adenovirus transduction efficiency in two primary leukemia isolates was improved by 3- and 4.5-fold. We were unable to demonstrate any benefit when adenovirus was admixed with protamine sulfate prior to intratumoral injection in a xenogeneic severe combined immunodeficient mouse melanoma tumor model. Further studies will determine whether polycations can improve intratumoral gene transfer.
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PMID:Polycations and cationic lipids enhance adenovirus transduction and transgene expression in tumor cells. 1050 54

Studies of metastasis can be accelerated and provide more mechanistic information using cell lines which reproducibly and aggressively metastasize, and which are accurately and easily detected in tissues at all stages of the metastatic process. Although reporter proteins such as green fluorescent protein (GFP) and beta-galactosidase have improved the tracking of tumor cells in vivo, their measurement has often been limited to visual observation and manual counting. In this study, we exploited the highly sensitive and objective quantitation provided by flow cytometry to characterize, in detail, the sequence of events associated with orthotopic metastasis in a highly aggressive mouse model. Following stable transfection of the MDA-MB-435 breast carcinoma cell line with GFP, we utilized an in vivo selection process to isolate a variant exhibiting increased primary tumor growth and metastasis. As few as one fluorescent tumor cell per 200,000 host cells could be accurately detected in dissociated tissues by flow cytometry, allowing us to demonstrate that metastatic cells migrate to the lungs of SCID mice very early after orthotopic implantation. Tumor burden in lungs increased in a smooth continuous manner, until death approximately eight weeks later. Levels of circulating tumor cells in blood were also detectable at an early timepoint, but remained relatively low throughout the course of secondary tumor development in the lungs. Surgical removal of the primary tumor at various times after inoculation significantly affected lung tumor burden, supporting the concept that circulating tumor cells in blood inefficiently initiate distal metastases. Furthermore, the continuing contribution to metastasis by the primary tumor was independent of tumor mass. The combined characteristics of enhanced orthotopic metastasis and quantitative detection in blood and tissues will make this a useful new model for the characterization of the multi-stage progression of cancer, and the preclinical evaluation of anti-neoplastic therapies.
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PMID:Characterization of spontaneous metastasis in an aggressive breast carcinoma model using flow cytometry. 1076 21

Genetic labeling of tumor cells with the Escherichia coli lacZ reporter gene, encoding the enzyme beta-galactosidase, is widely used for histochemical detection of micrometastases in mice. Recently, we have developed a novel, highly sensitive and specific immunocapture chemiluminescence assay for the quantitation of E. coli beta-galactosidase. This assay achieved a detection limit of 0.01 mU of E. coli beta-galactosidase per milliliter, and 97% signal recovery of purified enzyme added to mouse plasma. LacZ transduced MDA-MB-231 BAG human breast cancer cells grown in vitro released soluble beta-galactosidase into the culture medium, and the concentration found correlated with cell density. Growth of the same cells in nude mice produced readily measurable levels of E. coli beta-galactosidase enzyme activity in host plasma and a highly significant correlation could be demonstrated between the size of primary tumor xenografts and the host plasma level of E. coli beta-galactosidase activity. When mice bearing MDA-MB-231 BAG tumor xenografts were treated intravenously with a single injection of doxorubicin (5 mg/kg), the mean tumor volume after 16 days was reduced 4-fold in the group of doxorubicin-treated mice compared with saline-treated control mice, and the mean level of plasma E. coli beta-galactosidase was correspondingly reduced 3.8-fold in the doxorubicin-treated mice compared with control mice. Sensitive and specific measurement of soluble E. coli beta-galactosidase in blood, using an immunocapture chemiluminescence assay, thus provides objective assessment of tumor burden in mice xenografted with lacZ transduced human tumors. This assay may have important applications as a tool for determining the efficacy of new experimental anti-tumor agents.
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PMID:Plasma Escherichia coli beta-galactosidase as a marker of tumor burden and response to experimental anti-neoplastic therapy in nude mice xenografted with lacZ transduced human tumor cells. 1083 Jul 82


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