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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

BALB/c-derived tumor cells were transfected with recombinant Escherichia coli beta-galactosidase (beta-gal) genes which were inserted into IgM heavy chain gene derivatives, leading to expression of the resulting fusion protein in different cellular compartments. A beta-gal-specific, major histocompatibility complex (MHC) class I-restricted CD8+CD4- cytotoxic T lymphocyte (CTL) line of BALB/c origin raised against one transfectant expressing cytoplasmic beta-gal also lysed transfectants expressing beta-gal as membrane-inserted fusion protein, as well as transfectants secreting beta-gal. Our data show that MHC class I-restricted CTL can recognize fragments of nonviral cellular proteins, be they expressed as intracellular, membrane-inserted, or secreted products. The findings confirm and extend a hypothesis on the nature of minor histocompatibility (H) antigens formulated earlier.
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PMID:Protein-specific cytotoxic T lymphocytes. Recognition of transfectants expressing intracellular, membrane-associated or secreted forms of beta-galactosidase. 250 47

The nucleotide sequence of the virG gene for a transcriptional activator on the agropine-type hairy-root-inducing plasmid pRiA4 was determined. The sequence contained one possible open reading frame. The gene product with a molecular size of 26.5 kDa was identified by an Escherichia coli coupled-transcription-translation system using cloned virG plasmids as templates. However, neither an ATG nor a GTG start codon which could give rise to such a protein was identified in the nucleotide sequence. Instead, TTG was found as a candidate for the start codon. This TTG was preceded, like most other TTG start codons, by both a Shine-Dalgarno (SD) sequence and a T signal which are respectively complementary to the 3'-end region of 16S rRNA and the T psi loop of initiator tRNA. Further evidence for the start at TTG was obtained by gene fusion experiments. When the E. coli lacZ gene, whose expression entirely depends on the transcription and translation from upstream regions, was connected in-phase with virG either directly upstream or downstream of the TTG sequence, only the latter fused gene expressed the beta-galactosidase activity in Agrobacterium cells in response to a plant phenolic compound, acetosyringone. The TTG codon preceded by an SD sequence and a T signal is also conserved in the virG sequences from other three tumor-inducing plasmids previously reported.
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PMID:Putative start codon TTG for the regulatory protein VirG of the hairy-root-inducing plasmid pRiA4. 267 Jun 79

The chvB operon of Agrobacterium tumefaciens is required for bacterial attachment to plant cells and for efficient crown gall tumor formation. As defined by the virulence phenotypes of mutants with transposon insertions mapping in the region, the operon was previously mapped to a 5-kilobase (kb) stretch of chromosomal DNA. We report here that the operon is actually about 8.5 kb long and that it contains a 7-kb gene coding for a large membrane protein involved in the synthesis of cyclic beta-1,2-glucan. Mutants with transposon insertions within the 5-kb phenotypically defined operon do not synthesize this functional protein, do not synthesize beta-1,2-glucan, and do not form tumors. However, mutants with insertions that map up to 3.5 kb downstream of the phenotypically defined operon synthesize truncated proteins that are active in beta-1,2-glucan synthesis. These mutants form tumors. The truncated proteins correspond closely in size with the map positions of the insertions, suggesting that the insertions truncate the proteins by translational termination. A plasmid that contains only the phenotypically defined chvB operon also codes for a truncated protein. A fusion product between the protein and beta-galactosidase carried on a Tn3-HoHo1 insertion was observed in one mutant. Partial trypsin digestion of wild-type inner membranes generated truncated proteins that were active in beta-1,2-glucan synthesis, demonstrating that a large portion of the protein is not required for beta-1,2-glucan synthesis. The correlation between beta-1,2-glucan synthesis by the truncated proteins and tumorigenesis strongly implicates the polysaccharide product of this protein in tumor formation.
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PMID:Identification of the product of an Agrobacterium tumefaciens chromosomal virulence gene. 285 22

Four glycosidases (beta-galactosidase, alpha-mannosidase, alpha-fucosidase and beta-N-acetylglucosaminidase) were studied in chicken normal and regenerating liver, in turkey poult liver and in virus induced avian tumors--chicken hepatoma (strain Mc-29), Rous sarcoma (strain Schmidt-Ruppin) and turkey poult hemocytoblastoma nodules (strain Mc-31). The multiple forms of beta-N-acetylglucosaminidase were assayed as well. A particular enzyme pattern was found in the tumor lines under investigation. A characteristic property of hepatoma cells was the elevation of beta-galactosidase activity and of the former enzyme and that of beta-N-acetylglucosaminidase for the hemocytoblastoma. In Rous sarcoma the glycosidase activities (except that of alpha-fucosidase) were much lower, compared to the other two solid tumors. All enzyme activities were compared with those in the normal liver of the corresponding avian species, and with the liver of tumor bearing fowls and with regenerating chicken liver. Unlike the rat liver in the avian normal and tumor tissues the percentual ratio between the multiple forms A and B of beta-N-acetylglucosaminidase was found to be 30:70%.
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PMID:Glycosidases in normal and regenerating chicken liver, hepatoma Mc-29, Rous sarcoma, in turkey poult liver and hemocytoblastomes, provoked by the leukosis virus strain Mc-31. 298 24

A series of plasmid vectors has been constructed for the regulated, high level expression of foreign genes in E. coli. The vectors express cloned genes under the control of the tac promoter, which is a hybrid of trp and lac promoter sequences. Some of our expression vectors carry in addition to the tac promoter, the efficient lacZ ribosome binding site followed by unique cloning sites. These vectors can be used to express cloned genes directly, i.e. in an unfused, mature form. A second type of vector provides, in addition to the above regulatory elements, a translation initiation codon (ATG) for the expression of genes which have been isolated in an incomplete form (for example: cDNA). A third type of vector allow readily the construction of gene fusions to the E. coli beta-galactosidase gene, which may stabilize otherwise unstable eukaryotic proteins, and thus allows the production of high amounts of specific antigens in E. coli. With the above vectors, several eukaryotic and viral proteins, including SV40 small tumor antigen, human fibroblast interferon and herpes simplex glycoproteins have been expressed.
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PMID:Plasmid vectors for the regulated, high level expression of eukaryotic genes in Escherichia coli. 298 46

The construction and use of a Tn3-lac transposon, Tn3-HoHo1, is described. Tn3-HoHo1 can serve as a transposon mutagen and provides a new and useful system for the random generation of both transcriptional and translational lacZ gene fusions. In these fusions the production of beta-galactosidase, the lacZ gene product, is placed under the control of the gene into which Tn3-HoHo1 has inserted. The expression of the gene can thus be analyzed by monitoring beta-galactosidase activity. Tn3-HoHo1 carries a non-functional transposase gene; consequently, it can transpose only if transposase activity is supplied in trans, and is stable in the absence of this activity. A system for the insertion of Tn3-HoHo1 into sequences specifically contained within plasmids is described. The applicability of Tn3-HoHo1 was demonstrated studying three functional regions of the Agrobacterium tumefaciens A6 Ti plasmid. These regions code for octopine catabolism, virulence and plant tumor phenotype. The regulated expression of genes contained within each of these regions was analyzed in Agrobacterium employing Tn3-HoHo1 generated lac fusions.
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PMID:A Tn3 lacZ transposon for the random generation of beta-galactosidase gene fusions: application to the analysis of gene expression in Agrobacterium. 299 Sep 12

It was possible to define the effects of trehalose dimycolate (TDM), a glycolipid extracted from Mycobacterium tuberculosis, on mouse peritoneal macrophages more precisely using endotoxin-free culture conditions. TDM-elicited macrophages, when assayed in vitro in the absence of endotoxin, were unable to limit tumor growth; however, after a short treatment (4 h) with low doses of lipopolysaccharide (LPS; 1-10 ng/ml), they exhibited a strong cytostatic capacity against P815 mastocytoma cells. Thus, TDM injected in vivo did not activate macrophages fully but it primed them to respond in vitro to low doses of LPS, which provided the final stimulus for activation to antitumor competence. Macrophages elicited by an injection of killed group C Streptococci were also in a primed state; in contrast, thioglycollate-elicited macrophages were in a nonreceptive state. Besides LPS, concanavalin A (5 micrograms/ml), MDP (0.2-1 microgram/ml) and the ionophore A23187 (5 microM) can deliver the activation signal to TDM-primed macrophages. Primed macrophages were found to express several biochemical markers previously described as specific for activated macrophages (low levels of alkaline phosphodiesterase and beta-galactosidase, for example) and, although they were not cytotoxic for tumor cells, they had the capacity to release large amounts of H2O2. However, when pulsed by LPS or MDP, primed macrophages responded by further modifications in their metabolism: the rate of glucose consumption and the labeling of glycoproteins by D-[2-3H]mannose were greatly increased and the secretion of a polypeptide of 22 kDa was enhanced. The activation-associated biochemical markers are thus acquired in two steps. The ability to produce activated oxygen species is expressed earlier than the antitumoral activity.
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PMID:Macrophage activation by trehalose dimycolate requirement for an expression signal in vitro for antitumoral activity; biochemical markers distinguishing primed and fully activated macrophages. 300 1

Antibodies prepared against a human papilloma virus-1 (HPV-1) E4/beta-galactosidase fusion protein identified several polypeptides in HPV-1, but not HPV-2 or 4, induced papillomas. The major E4 protein, that represented up to 30% of total cellular protein, was a 16/17-K doublet which was purified by column chromatography and analysed for amino acid content. A peptide derived by chymotryptic digestion was purified by h.p.l.c. and subjected to amino acid sequencing. The unique sequence obtained, Gly-His-Pro-Asp-Leu-Ser-Leu, identified the 16/17-K doublet as a product of the HPV-1 E4 gene region. Antibodies to both the E4/beta-galactosidase fusion protein and the 16/17-K doublet identified two smaller polypeptides (10/11-K) which may represent spliced products of E4. We propose that the products of the HPV-1 E4 gene region are not classical DNA tumor virus early proteins and suggest that they play a role in virus maturation.
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PMID:Identification of the human papilloma virus-1a E4 gene products. 301 4

/ar, a tumor promoter-inducible protein secreted by mouse JB6 epidermal cells, is the murine homolog of rat osteopontin, or 44 kD bone phosphoprotein. We report here that 2ar is also related to pp69, a major phosphoprotein secreted by normal rat kidney cells. Antisera raised against pp69 and against beta-galactosidase-2ar fusion proteins are able to immunoprecipitate the same major phosphoproteins, of apparent Mr 55-69 kD, secreted by several rat and mouse cell lines. The levels of secreted protein and cytoplasmic mRNA are dramatically elevated in NIH 3T3 cells transformed with the human bladder cancer T24 (H-ras) oncogene. These results and the work of Senger and colleagues (Cancer Res., 45, 5818-5823, 1985) imply that enhanced secretion of 2ar/pp69/osteopontin by transformation of a wide variety of mammalian fibroblasts and epithelial cells is often correlated with tumorigenicity.
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PMID:Identification of the major phosphoprotein secreted by many rodent cell lines as 2ar/osteopontin: enhanced expression in H-ras-transformed 3T3 cells. 305 25

The Escherichia coli lacZ gene has been used as an indicator gene for the study of cell lineage in vivo. To adapt this marker for gene expression studies, a sequence encoding a modified beta-galactosidase and including the simian virus 40 large tumor nuclear location signal (nls-beta-Gal) has been introduced into vectors. In differentiated cells, multipotential cells, and embryos, the constructs led to the expression of an enzymatically active protein. Its location was examined by its beta-galactosidase activity or by using antibodies and electron microscopy. The results show that the nls-beta-Gal protein remains mainly located at the nuclear periphery (probably at the nuclear pores) but does not reach the nucleoplasm. It suggests that an interaction with the nuclear membrane is necessary but not sufficient for protein uptake into the nucleus. In multipotential cells, the expression of nuclear location signal LacZ (nls-LacZ) interferes neither with cell growth nor with differentiation. Using various lacZ constructs, the transcriptional activity of embryos was studied. At the two-cell stage, the promoters of the Rous sarcoma virus, simian virus 40, and the beta-actin gene are functional but the Moloney murine leukemia virus long terminal repeat is not. Thus, transcriptional specificity must already be present at the stage of activation of the embryonic genome.
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PMID:A beta-galactosidase hybrid protein targeted to nuclei as a marker for developmental studies. 311 43


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