| control of cytochrome p1-450 gene expression: analysis of a dioxin-responsive enhancer system. | we analyzed the function and sequence of a dioxin-responsive genomic element flanking the 5' end of the cytochrome p1-450 gene in high-activity variant mouse hepatoma cells. the element can regulate the mouse mammary tumor virus promoter. the element retains responsiveness to 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd) when the distance, the 5' or 3' position, and/or the 5' or 3' orientation with respect to the promoter are varied. the function of the element requires tcdd-receptor complexes. the ... | 1986 | 3010318 |
| consequences of widespread deregulation of the c-myc gene in transgenic mice: multiple neoplasms and normal development. | we have constructed a transgenic mouse strain in which a mammary tumor virus ltr/c-myc fusion gene is anomalously expressed in a wide variety of tissues. the deregulated c-myc transgene, now glucocorticoid inducible, contributes to an increased incidence of a variety of tumors, including those of testicular, breast, lymphocytic (b cell and t cell), and mast cell origin. the deregulated gene does not, however, otherwise disturb cell proliferation, nor does it interfere with normal development in ... | 1986 | 3011271 |
| physical state, expression and regulation of two glucocorticoid-controlled genes on bovine papilloma virus vectors. | we have studied the extrachromosomal maintenance and the transcription regulation of two glucocorticoid-inducible genes on bovine papilloma virus (bpv) vectors in c127 mouse fibroblasts. these genetic elements were the rat tryptophan oxygenase (toase) gene promoter, which is active in vivo only in hepatocytes, and the long terminal repeat of the mouse mammary tumor virus (mmtv-ltr). from both genes, fusions of the 5'-flanking region of the transcription unit to the bacterial gene for chloramphen ... | 1986 | 3012094 |
| direct detection of exogenous mouse mammary tumor virus sequences in lymphoid cells of balb/cfc3h female mice. | the presence of exogenous mouse mammary tumor virus (mmtv) (c3h) dna sequences in lymphoid tissue (spleen, bone marrow, and thymus) and nonlymphoid tissue (liver and kidney) of balb/cfc3h female mice was directly assessed by dna hybridization methods. lymphoid tissues were found positive for integrated mmtv(c3h) sequences in females as young as 4 weeks. in most samples, the level of splenic mmtv(c3h) infection was low (2 to 5%). infection remained throughout the life of the animal. the percentag ... | 1986 | 3012113 |
| sequence, topography and protein coding potential of mouse int-2: a putative oncogene activated by mouse mammary tumour virus. | a major proportion of carcinomas induced by mouse mammary tumour virus (mmtv) show evidence for proviral activation of a cellular gene, int-2, on chromosome 7. the sequence of 7869 bp of dna spanning the transcription unit of int-2 was determined and compared with that of a series of int-2-specific cdna clones derived from mammary tumour rna. the predicted positions of intron-exon boundaries, established by alignment of cdna and chromosomal dna sequences, indicate that the gene comprises at leas ... | 1986 | 3013624 |
| the endogenous mouse mammary tumour virus locus mtv-8 contains a defective envelope gene. | the mtv-8 associated provirus, gr40, is not expressed in vivo. however, upon transfection into rat xc cells, the two mmtv specific mrnas of 35s and 24s are transcribed. further, the level of these transcripts is augmented when the transfected cells are grown in the presence of dexamethasone (ponta et al., 1983). no virus can be detected in the medium of the transfected cells. intracellular protein analysis of these transfected cells shows that although apparently authentic gag proteins are synth ... | 1986 | 3014784 |
| 16 alpha-hydroxylation of estradiol: a possible risk marker for breast cancer. | from these results we may conclude that estradiol 16 alpha-hydroxylation is highly correlated with tumor incidence, and that the reaction is partly regulated by mmtv and the rest by genetic influences. elevated hydroxylation appears to be an autosomal dominant trait that is highly specific for estradiol. it is also pertinent that the product of the 16 alpha-hydroxyestrone reaction is a potent estrogen that is capable of binding covalently to amino acids and nucleotides, including the estrogen re ... | 1986 | 3014947 |
| early pathologic changes in experimental and human breast cancer: facts and comments. | | 1986 | 3014948 |
| regulatory sequences involved in the hormonal control of casein gene expression. | | 1986 | 3014951 |
| destabilization of cytoplasmic mouse mammary tumor rna by heat shock: prevention by cycloheximide pretreatment. | thermal stress of cultured mouse mammary carcinoma cells results in a rapid loss of basal and glucocorticoid-stimulated mouse mammary tumor virus (mmtv) rna. mmtv rna is almost nondetectable within 1-2 hr after a shift in the culture temperature to 42 degrees. actin mrna is stable over this time period. pretreatment of the cells with cycloheximide prevents the decay of mmtv rna. nuclear associated glucocorticoid receptor is not decreased but rather increased about 95% by the heat shock. the resu ... | 1986 | 3015134 |
| mammary tumorigenesis in feral species of the genus mus. | | 1986 | 3015500 |
| endogenous mmtv proviral genomes in feral mus musculus domesticus. | | 1986 | 3015501 |
| differential expression of endogenous mouse mammary tumor virus genes during development of the balb/c mammary gland. | expression of endogenous mouse mammary tumor virus sequences varied over the course of development of the mammary gland during primary pregnancy and lactation in virus-free balb/c mice. although rna from all regions of the genome was detected, both the level and temporal regulation of expression were different for long terminal repeat-, env-, and gag-pol-specific rnas. analysis of the methylation status of proviral dna indicated differential accessibility of the three endogenous units during dev ... | 1986 | 3016314 |
| characterization, chromosome assignment, and segregation analysis of endogenous proviral units of mouse mammary tumor virus. | in the course of analyzing sites of proviral integration in tumors induced by mouse mammary tumor virus (mmtv), we have isolated recombinant dna clones corresponding to the 5' and 3' ends of four endogenous mmtv proviruses present in balb/c and br6 mice. this has permitted the structural characterization of each locus by detailed restriction mapping and the preparation of dna probes specific for the cellular sequences flanking each provirus. these probes have been used to trace the segregation p ... | 1986 | 3016317 |
| differential transformation of c3h10t1/2 cells by v-mos: sequential expression of transformation parameters. | extremely small quantities of the product of the transforming gene v-mos of moloney murine sarcoma virus are able to efficiently transform cells. recent data indicate the existence of a threshold level for v-mos transformation of nih3t3 cells. using mouse mammary tumor virus long terminal repeat sequences or hybrid promoters consisting of mouse mammary tumor virus and moloney murine sarcoma virus long terminal repeat elements to express v-mos in c3h10t1/2 cells, we established cell lines represe ... | 1985 | 3016522 |
| molecular cloning of the mason-pfizer monkey virus genome: biological characterization of genome length clones and molecular comparisons to other retroviruses. | the molecular cloning of the dna provirus of mason-pfizer monkey virus (m-pmv) is described. fourteen independent clones of integrated m-pmv proviruses were isolated from a human embryo kidney cell line that had been previously derived from a single cell clone infected with m-pmv. characterization of these clones for size of insert, restriction pattern of flanking dna, and presence of repetitive dna in the flanking sequences revealed that 10 of the isolates were identical while the four remainin ... | 1986 | 3016990 |
| highly sensitive immunoadsorption procedure for detection of low-abundance proteins. | a procedure that virtually eliminates nonspecific adsorption of radiolabeled proteins during immunoprecipitation was devised utilizing staphylococcal cells containing protein a (staph a). immunoprecipitates (antigen-antibody complexes) were solubilized from staph a pellets into detergent micelles by incubation in a small volume of 1% sodium dodecyl sulfate (sds) at 23 degrees c for 10 min. to allow re-formation of immunocomplexes and rebinding to new staph a, the sds-solubilized material was dil ... | 1986 | 3017145 |
| hormone dependence and independence of mammary tumors in mice. | | 1986 | 3017886 |
| stoichiometric analysis of the specific interaction of the glucocorticoid receptor with dna. | purified preparations of activated glucocorticoid x receptor complex (gr) contain a mr 94,000 hormone-binding polypeptide co-purifying together with a mr 72,000 non-hormone-binding polypeptide (wrange, o., okret, s., radojcic, m., carlstedt-duke, j., and gustafsson, j.-a. (1984) j. biol. chem. 259, 4534-4541). gr binds selectively to discrete regions of dna in mouse mammary tumor virus (payvar, f., defranco, d., firestone, g.l., edgar, b., wrange, o., okret, s., gustafsson, j.-a., and yamamoto, ... | 1986 | 3017946 |
| tumor-specific idiotype vaccines. i. generation and characterization of internal image tumor antigen. | the concept of idiotype vaccines against tumor-associated antigens (taa) was tested in the dba/2 l1210 lymphoma subline, l1210/gzl. monoclonal antibodies against a taa that cross-reacts with the envelope glycoprotein gp52 of the mammary tumor virus were used to make hybridoma anti-idiotype antibodies (ab2). in this report we describe the characterization of monoclonal anti-idiotypic antibodies against the combining site of 11c1 (ab1), which recognizes a shared determinant of gp52 of mouse mammar ... | 1986 | 3018080 |
| exogenous mouse mammary tumor virus proviral dna isolated from a kidney adenocarcinoma cell line contains alterations in the u3 region of the long terminal repeat. | mouse mammary tumor virus (mmtv) is a b-type retrovirus which induces predominantly mammary carcinomas after a relatively long latency period. to date, very little is known about the reasons for the strict tissue specificity of mmtv. the balb/cf/cd strain of mice, which was infected with milk-borne mmtv (c3h), shows a high incidence of kidney adenocarcinomas, and our data suggest that mmtv might be involved in the formation of these tumors. newly integrated exogenous mmtv proviruses were found i ... | 1986 | 3018276 |
| nucleotide sequence and expression in vitro of cdna derived from mrna of int-1, a provirally activated mouse mammary oncogene. | the mouse int-1 gene is a putative mammary oncogene discovered as a target for transcriptionally activating proviral insertion mutations in mammary carcinomas induced by the mouse mammary tumor virus in c3h mice. we have isolated molecular clones of full- or nearly full-length cdna transcribed from int-1 rna (2.6 kilobases) in a virus-induced mammary tumor. comparison of the nucleotide sequence of the cdna clones with that of the int-1 gene (a. van ooyen and r. nusse, cell 39:233-240, 1984) show ... | 1985 | 3018519 |
| expression of mtv sequences introduced into the mouse germline. | | 1986 | 3018777 |
| spleen specific expression of an mmtv related transcript associated with the mtv-6 locus in balb/c mice. | we have detected an mmtv related transcript which is expressed in a spleen specific manner in balb/chea mice. using a recombinant inbred series between balb/chea and sts/a mice (c x s ri series) we have identified rna associated with the mtv-3 locus of the sts/a strain. this transcript initiates at the same site in the mmtv ltr as already reported for mtv-2 and mtv-8. the novel spleen specific mmtv transcript in the balb/chea strain has a different structure as compared to the transcripts associ ... | 1986 | 3019005 |
| site-specific rearrangements in the long terminal repeat of extra mouse mammary tumor proviruses in murine t-cell leukemias. | extra mmtv proviruses in t-cell leukemias of gr and c57/bl10 mice contain alterations in their long terminal repeat (ltr) sequence. the four different leukemias studied contain different deletions, but common hallmarks were observed around the recombination sites. at the 5' end of the deletions we observed a common nonamer sequence, agacaggtg, in two leukemias and an almost identical sequence, agagcaggtg, in two other leukemias. at the 3' end of the deletions we invariably found a common stretch ... | 1986 | 3019010 |
| a retrovirus vector expressing the putative mammary oncogene int-1 causes partial transformation of a mammary epithelial cell line. | in mammary tumors induced by the mouse mammary tumor virus (mmtv), the int-1 gene is frequently activated by adjacent proviral insertions and is thereby strongly implicated in tumorigenesis. to seek a direct biological effect of int-1 that would validate its proposed role as an oncogene, we constructed a retrovirus vector containing the gene and examined its effects on tissue culture cells. expression of int-1 in a mammary epithelial cell line caused striking morphological changes, unrestricted ... | 1986 | 3019559 |
| increased yield of mouse mammary tumor virus (mmtv) by cultivation of monolayer-derived mammary tumor cells in suspension. | the mjy-alpha epithelial-like mammary tumor cell line was adapted for cultivation in suspension using a shaker culture technique. replication of suspension (mjy-beta) cells was more sensitive than monolayer cells to decreases in the concentration of serum in the medium. comparison of amino acid incorporation and lactate production rates revealed additional differences between monolayer and suspension cultures. in addition, growth in suspension resulted in 10- to 400-fold increases in mouse mamma ... | 1986 | 3019991 |
| influence of age on induction of mammary tumors by diethylstilbestrol in c3h/hen mice with low murine mammary tumor virus titer. | c3h/hen female mice with low murine mammary tumor virus titer (mtv-) were fed diets containing a targeted concentration of 640 ppb diethylstilbestrol [(des) cas: 56-53-1; 4,4'-(1,2-diethyl-1,2-ethenediyl)bis-phenol]. mice were started on des at 3, 5, 7, or 9 weeks of age. some continued on the diet throughout the rest of their life-spans, whereas others were killed as soon as they had been fed des for 2, 4, 6, 8, 10, or 12 weeks. controls were also examined throughout the study. among mice kille ... | 1986 | 3020299 |
| activation of int-1 and int-2 loci in grf mammary tumors. | the mtv-2 locus is known to be associated with a high mammary tumor incidence (97%) and early development of mammary tumors (3-13 months) in gr mice. however, it was not previously known whether the provirus which resides at the mtv-2 locus is tumorigenic in and of itself or whether reintegration of proviruses generated from mtv-2 is required for tumorigenesis. foster-nursing gr mice on c57/bl mice eliminates the milk-borne source of gr virus, and allows the study of mtv-2 derived proviruses alo ... | 1986 | 3020781 |
| virology, genetics and immunology of murine lymphomagenesis. | | 1986 | 3021223 |
| genetic marker patterns and endogenous mammary tumor virus genes in inbred mouse strains of japan. | in order to establish the genetic relatedness of the inbred mouse strains kept in nara, genetic marker patterns were determined in conjunction with a study on endogenous mammary tumor viral genes in these strains. isoenzyme patterns combined with patterns of other genetic markers, show that the unrelatedness between various inbred strains of the dd stock is as high or even higher as between strains of known different origin and geneology. based on endogenous viral gene patterns the dd stock deri ... | 1986 | 3021480 |
| nucleotide sequence of human endogenous retrovirus genome related to the mouse mammary tumor virus genome. | we determined the complete nucleotide sequence of the human endogenous retrovirus genome herv-k10 isolated as the sequence homologous to the syrian hamster intracisternal a-particle (type a retrovirus) genome. herv-k10 is 9,179 base pairs long with long terminal repeats of 968 base pairs at both ends; a sequence 290 base pairs long, however, was found to be deleted. it was concluded that a composite genome having the 290-base-pair fragment is the prototype herv-k provirus gag (666 codons), prote ... | 1986 | 3021993 |
| structure of a human retroviral sequence related to mouse mammary tumor virus. | human sequences that are related to the mouse mammary tumor virus (mumtv) genome were cloned from breast tumor cell dna. of 100 recombinants, only 1 hybridized with two different probes from separate regions of the mumtv genome (gag-pol and long terminal repeat [ltr]). this sequence, nmwv 4, was shown to have a proviruslike structure. hybridization to digests of normal and tumor cell dna indicated that nmwv 4 and a few closely related sequences are endogenous to the human genome. the regions tha ... | 1986 | 3022006 |
| reversible suppression of mouse mammary tumor virus replication by prolonged glucocorticoid exposure. | expression of mouse mammary tumor virus (mumtv) in mjy-alpha mammary tumor cells was only transiently stimulated by exposure to 14 microm hydrocortisone (hc). short-term hc treatment for 24-48 hours resulted in twofold-to-fivefold increases in levels of mumtv polypeptide synthesis, mumtv surface antigen expression, and mumtv production. hc treatment also induced quantitative alterations in glycosylation of mumtv precursors pr79env and pr76env. in contrast, prolonged exposure to 14 microm hc for ... | 1986 | 3022058 |
| mouse mammary tumor virus mediated transfer and expression of neomycin resistance to infected cultured cells. | the mammary gland specific, glucocorticoid controlled expression of mmtv makes it an ideal candidate for the basis of a nonpromiscuous regulated retroviral vector system. we have previously constructed an mmtv proviral variant that gives rise to virus particles upon introduction into cultured cells. this was used to construct a defective mmtv provirus in which the mmtv env gene was replaced by the neomycin resistance gene under the control of the herpes simplex thymidine kinase promotor. the def ... | 1986 | 3022473 |
| protein glycosylation regulates the externalization of two distinct classes of glucocorticoid-induced glycoproteins in rat hepatoma cells. | the relationship of protein glycosylation to the externalization of glucocorticoid inducible alpha1-acid glycoprotein and mouse mammary tumor virus glycoproteins was examined in m1.54, a clonal population of mouse mammary tumor virus-infected rat hepatoma cells. multiple freeze-thaw of isolated microsomes revealed that while alpha 1-acid glycoprotein is carried through the cell as a soluble component of vesicles, extracellular viral glycoproteins are initially membrane-associated. at concentrati ... | 1986 | 3022823 |
| the v-mos and h-ras oncogene expression represses glucocorticoid hormone-dependent transcription from the mouse mammary tumor virus ltr. | we have subjected the viral mos oncogene (v-mos), the activated human h-ras oncogene [h-ras (a)] and the normal human h-ras protooncogene [h-ras (n)] to the transcriptional regulation of glucocorticoid hormones by in vitro recombination with the promoter region of the mouse mammary tumor virus long terminal repeat (mmtv ltr) and transfection into nih 3t3 cells. cell clones were selected which exhibit a transformed phenotype strictly dependent on the presence of hormone in the growth medium. the ... | 1986 | 3023051 |
| transformation and stimulation of dna synthesis in nih-3t3 cells are a titratable function of normal p21n-ras expression. | a plasmid has been constructed which contains the normal human n-ras proto-oncogene under the transcriptional control of the steroid-sensitive promoter of the mouse mammary tumor virus long terminal repeat. this plasmid has been introduced into nih-3t3 cells producing a clone of cells, t15, which is phenotypically normal in the absence of the transcription inducer, dexamethasone, and transformed when treated with high levels of the inducer. at lower levels of dexamethasone, both morphological tr ... | 1986 | 3023052 |
| the hormone regulatory element of mouse mammary tumour virus mediates progesterone induction. | sequences within the long terminal repeat region (ltr) of mouse mammary tumour virus (mmtv) confer progestin inducibility to either the tk-promoter or the mmtv-promoter in t47d cells, a human mammary tumour cell line which possesses high constitutive levels of progesterone receptor. in a clone of mcf7 cells, another human mammary tumour cell line with a low level of progesterone receptor, as well as in rat fibroblasts, glucocorticoid but not progestin induction is observed. the effect of the pro ... | 1986 | 3023063 |
| partial transformation of mouse fibroblastic and epithelial cell lines with the v-myc oncogene. | to investigate the role of the myc gene in mammalian cell transformation, plasmid constructs containing the v-myc oncogene and a co-selectable g418 resistance marker were introduced into both mouse fibroblasts (nih-3t3) and bladder epithelial cells (bbn3 and bbn7). after transfection or microinjection of dna, no transformed foci could be detected on confluent monolayers but, when the cells were cultured under conditions in which individual cells were allowed to grow and form colonies, morphologi ... | 1987 | 3023119 |
| glucocorticoid-regulated glycoprotein maturation in wild-type and mutant rat cell lines. | glucocorticoid hormones can regulate the posttranslational maturation of mouse mammary tumor virus (mtv) precursor polyproteins in m1.54, a stably infected rat hepatoma cell line. we have used complement-mediated cytolysis to recover variants of m1.54 that fail to express mtv cell surface glycoproteins in a hormone-regulated manner (firestone, g.l., and k.r. yamamoto, 1983, mol. cell. biol., 3:149-160). one such clonal isolate, cr4, is similar to wild-type with respect to synthesis of mtv mrnas, ... | 1986 | 3023398 |
| mammary tumors in feral mice lacking mumtv dna. | two mammary tumors developed in feral mice treated with dimethylbenzanthracene. the tumors, livers, and spleens of these animals contained no mumtv proviral dna. neither tumor had amplified or rearranged int-1 or int-2 loci. this demonstrates that mammary tumorigenesis can occur in mice in the absence of endogenous and exogenous mumtv. | 1985 | 3023583 |
| functional analysis of the glucocorticoid regulatory elements present in the mouse mammary tumor virus long terminal repeat. a synthetic distal binding site can replace the proximal binding domain. | transcription of mouse mammary tumor virus dna is stimulated by steroid hormones. the dna sequences involved in this regulation are located in the viral long terminal repeat between positions -200 and -50 with respect to the transcription initiation site. in this region four, one distal and three proximal, in vitro binding sites for the glucocorticoid hormone-receptor complexes have been identified. we have prepared a series of 5' and 3' deletions of this region, using the exonuclease exoiii. co ... | 1986 | 3023640 |
| distinct sequence elements involved in the glucocorticoid regulation of the mouse mammary tumor virus promoter identified by linker scanning mutagenesis. | in the proviral dna of mouse mammary tumor virus (mmtv), sequences up to approximately equal to 200 base-pairs from the rna start site are required for stimulation of transcription by glucocorticoid hormones in cultured cells. a total of 26 mutant plasmids with clustered point mutations or small deletions in the hormone control region of the mmtv long terminal repeat were constructed, linked to the coding portion of the herpes simplex virus thymidine kinase gene, and introduced by transfection i ... | 1986 | 3023641 |
| a new common integration region (int-3) for mouse mammary tumor virus on mouse chromosome 17. | mus musculus subsp. musculus (czech ii) mammary tumor dna frequently contains an integrated proviral genome of the mouse mammary tumor virus (mmtv) within a specific 0.5-kilobase-pair region of the cellular genome (designated int-3). viral integration at this site results in activation of expression of an adjacent cellular gene. we mapped int-3 to mouse chromosome 17 by analysis of psti-restricted cellular dnas from mouse-hamster somatic cell hybrids. restriction analysis of cellular dna from (c ... | 1987 | 3023699 |
| mammary tumorigenesis in feral mice: identification of a new int locus in mouse mammary tumor virus (czech ii)-induced mammary tumors. | a population of mus musculus subsp. musculus (czech ii), recently isolated from the wild, lack endogenous mouse mammary tumor virus (mmtv) proviral genomes. some of these mice carry an infectious mmtv [designated mmtv (czech ii)] that is transmitted in the milk and is associated with mammary tumor development. this virus is distinct from laboratory strains of mmtv present in inbred mice. an mmtv (czech ii) genome was found within a 0.5-kilobase region of the cellular genome in five of 16 czech i ... | 1987 | 3023708 |
| characterization and chromosome assignment of the human homolog of int-2, a potential proto-oncogene. | int-2 is one of two cellular genes (int-1 and int-2) currently implicated in the genesis of mammary carcinomas by mouse mammary tumor virus and may constitute a novel cellular proto-oncogene. using low-stringency hybridization with mouse int-2 probes, we established that homologous genes exist in a variety of mammalian species, including humans, but failed to detect related sequences in other classes and phyla. recombinant bacteriophage clones and a single cosmid encompassing the human int-2 gen ... | 1986 | 3023852 |
| a distinct glucocorticoid hormone response regulates phosphoprotein maturation in rat hepatoma cells. | glucocorticoid hormone-dependent maturation of the mouse mammary tumor virus (mmtv) phosphorylated polyprotein (pr74) allows experimental access to certain posttranslational regulatory circuits under steroid control in m1.54 cells, an mmtv-infected rat hepatoma cell line. pulse-chase experiments revealed that [35s]methionine-labeled pr74 synthesized in uninduced cells could be converted posttranslationally into p24, a stable phosphorylated maturation product, only after 4 h of exposure to 1 micr ... | 1986 | 3023857 |
| androgen regulation by the long terminal repeat of mouse mammary tumor virus. | mouse mammary tumor virus (mmtv) has long been implicated in mouse mammary carcinogenesis, and it is now well established that the long terminal repeat (ltr) contains regulatory sequences responsible for glucocorticoid-mediated induction of viral rna. however, we have demonstrated previously that androgens as well as glucocorticoids can regulate mmtv rna in the s115 mouse mammary tumor cell line. to determine if androgens act directly on the ltr in these cells, plasmids were constructed with the ... | 1986 | 3023950 |
| synergism of v-myc and v-ha-ras in the in vitro neoplastic progression of murine lymphoid cells. | murine bone marrow was either singly or doubly infected with retroviral vectors expressing v-myc (ok10) or v-ha-ras. the infected bone marrow was cultured in a system that supports the long-term growth of b-lineage lymphoid cells. while the v-myc vector by itself had no apparent effect on lymphoid culture establishment and growth, infection with the v-ha-ras vector or coinfection with both v-myc and v-ha-ras vectors led to the appearance of growth-stimulated cell populations. clonal pre-b-cell l ... | 1986 | 3023969 |
| insertion elements and transitions in cloned mouse mammary tumour virus dna: further delineation of the poison sequences. | the provirus of mouse mammary tumour virus (mmtv) is reputed to contain sequences within the viral gag gene that prevent or inhibit its propagation as a recombinant dna clone in escherichia coli. here we report the successful isolation of several lambda and plasmid clones comprising the 5' virus-host dna junction fragments from integrated mmtv proviruses in br6 mice. although the lambda clones appeared intact, almost all of the plasmids were found to contain the bacterial insertion sequences is1 ... | 1986 | 3024101 |
| 1731, a new retrotransposon with hormone modulated expression. | we report here the characterisation of 1731, a new copia-like element of drosophila melanogaster. 1731 was first isolated in a screening for ecdysterone modulated genes. this element is about 4.6 kb long and is flanked by two long terminal repeats (ltrs) 336 base pairs in length. the whole 1731 element is transcribed into polya+ rnas, and these transcripts decrease rapidly upon hormonal treatment. 1731 is moderately repeated in the fly genome and slightly amplified in kc/cells where extrachromos ... | 1986 | 3024127 |
| monoclonal antibodies to the v-fes product and to feline leukemia: virus p27 interspecies-specific determinants encoded by feline sarcoma viruses. | monoclonal antibodies to p27 gag and v-fes specific determinants on the gag-onc poly-protein encoded by snyder-theilen feline sarcoma virus (st-fesv) were prepared. in order to obtain hybridoma clones specific to the antigenic determinants encoded by the fesv genome, lou rats were immunized with st-fesv-transformed, virus-nonproducing syngeneic cells, and boosted with either the same cells or affinity-purified feline leukemia virus (felv) p27. three distinct clones reactive to both felv p27 and ... | 1986 | 3024406 |
| human monoclonal antibodies derived from lymph nodes of a patient with breast carcinoma react with mumtv polypeptides. | nine human hybridoma cell lines were established from a fusion of axillary lymph node lymphocytes of a patient with breast ductal carcinoma with a human lymphoblastoid cell line. the human hybridoma nature of the fusion products was confirmed by chromosomal analysis and hla typing. the hybridomas are stable over a year of growth, and can be frozen, thawed and regrown. the carcinoma cells of the patient harbor mouse mammary tumor virus (mumtv) cross-reacting antigens. the patient's serum and the ... | 1987 | 3024800 |
| lymphohematopoietic and other malignant neoplasms occurring spontaneously in transgenic mice carrying and expressing mtv/myc fusion genes. | | 1986 | 3024925 |
| multiple hormone-inducible enhancers as mediators of differential transcription. | sets of genes under a common regulatory control in a given cell type are often differentially transcribed. the possibility that this differential transcription can be modulated by the number or strength of cis-acting regulatory sequences associated with a given gene was tested by using the glucocorticoid-responsive enhancer element associated with the mouse mammary tumor virus promoter. results indicate that differential levels of hormone-inducible gene expression can be modulated in an additive ... | 1986 | 3025659 |
| steroid-free glucocorticoid receptor binds specifically to mouse mammary tumour virus dna. | steroid hormones are thought to modulate gene expression through their interaction with receptor proteins. the intracellular localization of unoccupied receptor proteins has been a subject of controversy: free glucocorticoid receptor appears to reside in the cytoplasm and moves to the cell nucleus only after binding the steroid. the purified hormone-bound glucocorticoid receptor has been shown to bind selectively to hormone regulatory elements (hre) in the vicinity of hormonally-inducible promot ... | 1986 | 3025742 |
| oestradiol induction of a glucocorticoid-responsive gene by a chimaeric receptor. | steroid hormone receptors are a class of cell-specific trans-acting transcription regulatory factors whose activity is controlled by specific binding of the hormone. the hormone-receptor complex appears to associate with promoter/enhancer elements of specific target genes, resulting in activation of transcription (see refs 1 and 2 for reviews). sequence comparison between the oestrogen, glucocorticoid and progesterone receptors (refs 7, 8 and unpublished results) and site-directed mutation analy ... | 1987 | 3025750 |
| purification of antigens of mammary tumor of the mouse by gel filtration. | this study was designed to isolate the biologically active components from a perchloric acid (pca) extract of mammary tumor virus (mtv)-induced mouse mammary tumors (ammt) previously shown to be capable of inducing dna synthesis in spleen cells of mice presensitized by inoculation of viable syngeneic mammary tumor cells. ammt (450 mg) was eluted fom an ultrogel aca54 column with separation range of 5-70k in a buffer containing tris-sodium chloride and edta. two fractions were separated with esti ... | 1986 | 3026423 |
| steroid-dependent interaction of transcription factors with the inducible promoter of mouse mammary tumor virus in vivo. | we have used exonuclease protection in vivo as an assay to detect interaction of nuclear factors with the steroid-inducible promoter of mouse mammary tumor virus. binding of two factors is detected uniquely at the steroid-activated promoter, and results in protection of sequences between -82 and approximately +12 one factor is identified as the murine homolog of nuclear factor 1. the second (designated factor i) binds downstream of nuclear factor 1 and protects sequences extending over the cap s ... | 1987 | 3026639 |
| complete nucleotide sequence of a milk-transmitted mouse mammary tumor virus: two frameshift suppression events are required for translation of gag and pol. | we sequenced two recombinant dna clones constituting a single provirus of the milk-transmitted mouse mammary tumor virus characteristic of br6 mice. the complete provirus is 9,901 base pairs long, flanked by 6 base-pair duplications of cellular dna at the site of integration. five extensive blocks of open reading frame corresponding to the gag gene, the presumed protease, the pol and env genes, and the open reading frame orf within the long terminal repeat of the provirus were readily discernibl ... | 1987 | 3027377 |
| a rare common integration site of proviruses of the mouse mammary tumor virus in p-type mammary tumors of mouse strain gr. | the mouse mammary tumor virus (mmtv) can induce mammary tumors in mice by proviral activation of the cellular oncogenes int-1 or int-2. activation of these genes, however, is observed in only a few hormone- and pregnancy-dependent mammary tumors of the mouse strain gr. to study the possible involvement of other oncogenes we cloned three mmtv proviral-host fragments (mt 40, 42, and 53) from different mammary tumors of gr with a single acquired mmtv provirus. from a genomic library of normal mouse ... | 1987 | 3027974 |
| [antibodies interacting with the proteins of the mammary cancer virus (mmtv) in the sera of healthy women]. | using enzyme-linked immunoassay (elisa), sera of 405 women without breast cancer were screened for the presence of antibodies to mouse mammary tumour virus proteins. 16 donors with positive sera were identified (3.96 +/- 0.97%). an attempt was made to establish the correlation between the age, ovarian activity, benign breast disease and other factors and the appearance of antibodies to mouse mammary tumour virus. no statistically significant differences have been revealed among women aged 20-29 ... | 1987 | 3028532 |
| proteins antigenically related to peptides encoded by the mouse mammary tumour virus long terminal repeat sequence are associated with intracytoplasmic a particles. | intracytoplasmic a particles (cap), previously identified as cytoplasmic nucleocapsid precursors to mouse mammary tumour virus (mmtv), reacted strongly in immunodiffusion tests with polyclonal antibodies raised against synthetic oligopeptides derived from the open reading frame (orf) in the long terminal repeat (ltr) of mmtv. in western blots, several cap proteins (p80, p72-68, p36, p32, p18-12) were reactive with polyclonal antibodies raised against three separate ltr orf synthetic peptides. di ... | 1987 | 3029286 |
| activation of int-1 and int-2 mammary oncogenes in hormone-dependent and -independent mammary tumors of gr mice. | mammary tumors in the gr mouse strain are caused by the expression of an endogenous provirus of the mouse mammary tumor virus (mmtv). the tumors progress from a hormone-dependent growth phase to autonomous, hormone-independent growth. we studied proviral insertion of mmtv at the int-1 and int-2 mammary oncogenes and the transcription of these genes during progression of a series of transplanted mammary tumors. during the hormone-dependent phase, 6 of 15 transplanted tumors were positive for prov ... | 1987 | 3029401 |
| antibodies to mumtv proteins in the sera of mammary carcinoma patients' healthy daughters. | the presence of antibodies to mumtv-related proteins in sera of 31 mammary carcinoma patients' healthy daughters have been tested by indirect immunoperoxidase method (elisa). ten of them (32.3 +/- 8.4%) reacted with mumtv proteins preparations, but not with mulv, ralv, ssv, mpmv proteins or preparations of mouse embryonic tissues. the percent of positive sera in this group is almost ten times higher than among women without breast cancer in family history (earlier published data). by immunoblott ... | 1986 | 3030219 |
| [a protein related to the main core protein of the mouse mammary cancer virus in a microparticle fraction of human milk]. | virus-like density fractions (vdf) have been prepared from 6 specimens of human milk by ultracentrifugation of milk sera and recentrifugation of pellet through 35% sucrose or by separation in sucrose density gradient. using electroblotting and enzyme-linked antibody probes, the protein with a molecular weight of 27 kd, reacting with serum against mmtv gag proteins, was identified in 5/6 of milk vdf. the absence (or very low amounts) of this protein among proteins of milk, fat globule membranes a ... | 1987 | 3030463 |
| induction of c-ha-ras transcription in rat cells by simian virus 40 large t antigen. | rat 3y1 cells expressing simian virus 40 large t antigen under the control of the mouse mammary tumor virus long terminal repeat were established. the amount of c-ha-ras mrna in those cells was elevated by about 20 times in parallel with large t antigen after exposure to dexamethasone for 48 h. in chloramphenicol acetyltransferase assays with a plasmid containing the c-ha-ras-1 promoter the increase in c-ha-ras mrna was shown to occur at the transcriptional level. | 1987 | 3031481 |
| nonrandom distribution of mmtv proviral sequences in the mouse genome. | integrated sequences of mouse mammary tumor virus (mmtv) have been localized in the genomes of five inbred mouse strains (balb/c, c3h, dba/2, a.th, 129-sv) and one mammary tumor cell line (gr). two major classes of mmtv sequences have been detected in mouse dna fractions as obtained by cs2so4/bamd (3,6-bis-(acetatomercurimethyl)dioxane) density gradient centrifugation. the first one corresponds to previously described endogenous sequences (mtv loci), whereas the second one corresponds to endogen ... | 1987 | 3031617 |
| application of a protein-blotting procedure to the study of human glucocorticoid receptor interactions with dna. | to exert their effects, glucocorticoid receptor complexes interact selectively with dna sequences known as glucocorticoid regulatory elements. we have studied the interaction between human glucocorticoid receptors and mouse mammary tumor virus (mmtv) dna by means of a procedure that permits analysis after immobilization of the receptor on nitrocellulose. proteins from crude cytosolic or nuclear extracts were electrophoresed on nadodso4/page gels, soaked in a urea buffer to remove nadodso4, trans ... | 1987 | 3031647 |
| glucocorticoid-dependent maturation of viral proteins in mouse lymphoma cells: isolation of defective and hormone-independent cell variants. | maturation of mouse mammary tumor virus proteins is dependent on glucocorticoid hormones in w7mg1, a stably infected mouse t-lymphosarcoma cell line derived from weh17. we used an immunological procedure to select variant cell lines with altered levels of viral glycoproteins on the cell surface. one variant, w7m329a, expressed lower-than-normal levels of the major viral glycoprotein, gp52env, on the cell surface before and after exposure to hormone. two other variants, w7m302b and w7m326.4, expr ... | 1987 | 3031826 |
| mammary preneoplasia and tumorigenesis in the balb/c mouse: structure and modification of mouse mammary tumor virus dna sequences. | mouse mammary tumor virus (mmtv) dna sequences were examined in mammary tissues from balb/c mice, including both preneoplastic hyperplastic alveolar nodule (han) outgrowth lines, tumors derived from those preneoplastic tissues, and dmba-induced mammary tumors. over 60 different han and tumors samples were analyzed. the d2 han line contained one additional provirus, whereas cv-2 and cv-4 han lines that are infected with exogenous virus exhibited multiple virus integration events. d2 tumors showed ... | 1987 | 3031894 |
| differential effects of steroid hormones on parameters of cell growth. | steroid hormones affect the growth of many tumor cells both in vivo and in vitro. growth of cells in vitro can be studied as either anchorage dependent (monolayer culture) or anchorage independent (suspension culture), and in each case, steroid hormones can alter log-phase proliferation rate, saturation density, or cell morphology. results presented here demonstrate that different steroid hormones can have different effects on each of these parameters in breast cancer cells. in androgen-responsi ... | 1987 | 3032417 |
| coexpression of mmtv/v-ha-ras and mmtv/c-myc genes in transgenic mice: synergistic action of oncogenes in vivo. | we have derived and mated separate strains of transgenic mice that carry either the v-ha-ras or the c-myc gene driven by the mouse mammary tumor virus (mmtv) promoter/enhancer. mice carrying the mmtv/v-ha-ras transgene manifest two distinct disturbances of cell growth. the first, a benign hyperplasia of the harderian lacrimal gland, is diffuse, involves the entire gland, and likely requires only the abnormal action of the v-ha-ras gene. the second involves the focal development of malignancies o ... | 1987 | 3032456 |
| the endogenous retrovirus mtv-8 on mouse chromosome 6 maps near several kappa light chain markers. | endogenous retroviruses are known to affect expression of cellular genes in the vicinity of their integration sites. the endogenous mouse mammary tumor provirus (mtv-8) previously has been reported to reside on mouse chromosome 6 near the immunoglobulin kappa chain locus. using pairs of mouse strains on the balb/c (mtv-8 positive) and c58 (mtv-8 negative) backgrounds which are congenic for chromosome 6 genetic markers, we have confirmed the chromosome assignment of this provirus. moreover, we ha ... | 1987 | 3032783 |
| a standardized nomenclature for endogenous mouse mammary tumor viruses. | we propose a revised standardized nomenclature for endogenous mouse mammary tumor viruses based on characterization by molecular cloning techniques and genetic segregation data. | 1987 | 3033291 |
| expression of the epstein-barr virus gp350/220 gene in rodent and primate cells. | the gene encoding the epstein-barr virus envelope glycoproteins gp350 and gp220 was inserted downstream of the cytomegalovirus immediate-early, moloney murine leukemia virus, mouse mammary tumor virus, or varicella-zoster virus gpi promoters in vectors containing selectable markers. host cell and recombinant vector systems were defined which enabled the isolation of rodent or primate cell clones which expressed gp350/220 in substantial quantities. continued expression of gp350/220 required maint ... | 1987 | 3033311 |
| oestradiol 16 alpha-hydroxylase: a risk marker for breast cancer. | 17-oxidation and 2- and 16 alpha-hydroxylation of oestradiol show important correlations with biological aspects of breast cancer in women and mice. the presence of mouse mammary tumour virus may lead to increased 16 alpha-hydroxylation. 16 alpha-hydroxyoestrone (which may be generated in an autocrine manner) forms covalent linkages with amino groups on proteins and nucleotides. | 1986 | 3034420 |
| oncogene expression during progression of mouse mammary tumor cells; activity of a proviral enhancer and the resulting expression of int-2 is influenced by the state of differentiation. | the rac cell lines are derived from a mammary tumor induced by the mouse mammary tumor virus (mmtv). polygonal cells have retained many characteristics of epithelial cells and induce adenocarcinomas; cuboidal cells are poorly tumorigenic; and elongated cells produce highly malignant sarcoma-like tumors. mmtv proviral integrations, one of which has cis-activated the int-2 gene, demonstrated that the lines are clonal descendents from a single tumor cell. polygonal cells have a high constitutive ex ... | 1987 | 3034568 |
| transfection of the int-1 mammary oncogene in cuboidal rac mammary cell line results in morphological transformation and tumorigenicity. | the int-1 gene is often activated by proviral insertion in mouse mammary tumors. direct evidence for the normal function of this gene and its role in tumorigenesis has therefore been lacking. to examine possible biological effects of int-1 activation in in vitro cell systems, we have constructed recombinant molecules of genomic int-1 dna, transcriptionally activated by retroviral promoters. transfection of these constructs into cuboidal rac311c mammary cells leads to morphological transformation ... | 1987 | 3034569 |
| the hormone response element of the mouse mammary tumour virus dna mediates the progestin and androgen induction of transcription in the proviral long terminal repeat region. | mouse mammary tumour virus (mmtv) gene expression has been shown to be regulated by glucocorticoids. a hormone response element (hre) located between -202 and -59 upstream of the start of transcription in the long terminal repeat (ltr) region of the proviral dna is required for this induction. we have investigated the role played by the hre in the induction of mmtv ltr transcription by other classes of steroid hormones. chimaeric constructs containing the hre and the authentic ltr promoter linke ... | 1987 | 3034586 |
| expression of retroviral vectors in transgenic mice obtained by embryo infection. | pre-implantation embryos were infected with the retroviral vector mmcv-neo, which carries the neomycin resistance (neo) gene and the v-myc gene. three transgenic substrains (m-tkneo 1-3) were derived which stably transmit a single intact copy of the vector. in all of the substrains, expression of the neo gene from the internal thymidine kinase (tk) promoter was detected, with two of the substrains expressing the gene in all tissues analysed. in the third substrain, the vector had integrated on t ... | 1987 | 3034588 |
| functional differentiation of virgin mouse mammary epithelium in explant culture is dependent upon extracellular proline. | depletion of proline from insulin, hydrocortisone, and prolactin-containing medium prior to incubating virgin mouse mammary explants prevents both dna synthesis and functional differentiation in the mammary epithelial cells; however, dna synthesis in the mammary stroma and total incorporation of radioactive amino acids into total protein appears to continue without hindrance. removal of glycine instead of proline had no deleterious effect on either dna replication in the hormone-stimulated epith ... | 1987 | 3034921 |
| regulatory sequences of endogenous mouse mammary tumor virus locus mtv-8 from different mouse strains. | | 1987 | 3035491 |
| two efficient ribosomal frameshifting events are required for synthesis of mouse mammary tumor virus gag-related polyproteins. | the primary translation products of retroviral pol genes are polyproteins initiated in an upstream gene (gag). to investigate the manner in which the gag-initiated polyproteins of the mouse mammary tumor virus are produced, we determined the nucleotide sequence of a 1.8-kilobase dna fragment that spans the region between gag and pol in the c3h strain of mouse mammary tumor virus. the sequence reveals three overlapping open reading frames: the first encodes products of gag (p27gag and p14gag); th ... | 1987 | 3035577 |
| characterization and sequence-specific binding to mouse mammary tumor virus dna of purified activated human glucocorticoid receptor. | activated glucocorticoid receptor (gr) from the human cell line hela s3 was purified by differential chromatography on dna-cellulose followed by deae-sepharose chromatography to 50-60% homogeneity according to sodium dodecyl sulfate gel electrophoresis and densitometric scanning of silver-stained gels. these gels routinely demonstrated a main band of mr 94,000 (94k band) and two minor bands of mr 79,000 (79k band) and 39,000 (39k band), respectively. photoaffinity labeling indicated that the hor ... | 1987 | 3036207 |
| responses of serum from breast cancer patients to murine mammary tumor virus: fact or artifact? | for determination of whether breast cancer patients possessed specific serological responses to murine mammary tumor virus (mumtv), igg-binding levels were monitored by antibody binding to electrophoretically separated viral proteins (western blotting and immunodetection) and by the enzyme-linked immunosorbent assay (elisa) against a panel of five structural proteins (gp55, gp34, p28, p18, and p12) purified from milk-borne mumtv of the riii isogeneic mouse strain. no significant antibody reactio ... | 1987 | 3037149 |
| mammary cancer stages in balb/cv mice: mouse mammary tumor virus expression and virus-host interactions. | a unique subline of balb/c mice, designated "balb/cv," exhibits an intermediate mammary tumor incidence (47%) and harbors a distinct milk-transmitted mouse mammary tumor virus (mmtv). virus expression and virus-host interactions were examined during the different stages of mammary tumorigenesis (normal, preneoplastic, and neoplastic) in the balb/cv system. protein immunoblot analyses established the presence of correctly processed (balb/cv)mmtv structural proteins in all types of balb/cv mammary ... | 1987 | 3037152 |
| glucocorticoid-regulated compartmentalization of cell surface-associated glycoproteins in rat hepatoma cells: evidence for an independent response that requires receptor function and de novo rna synthesis. | the role of glucocorticoid hormones in the compartmentalization of cell surface-associated mouse mammary tumor virus (mmtv) glycoproteins was examined in m1.54, a cloned line of mmtv-infected rat hepatoma tissue culture cells. the expression of cellular [2-3h]mannose-labeled and cell surface 125i-labeled mmtv glycoproteins was examined throughout a time course of exposure to dexamethasone, a synthetic glucocorticoid. posttranslational localization of cell surface mmtv glycoproteins required 6 h ... | 1987 | 3037324 |
| context-dependent gene expression: cis-acting negative effects of specific procaryotic plasmid sequences on eucaryotic genes. | a sequence element within pbr322 dna mediates a cis-acting negative effect on expression from eucaryotic genes in transient expression assays. the negative element overlaps with sequences that inhibit dna replication, but its effect is observed in the absence of detectable replication of transfected dna. | 1987 | 3037330 |
| structural alterations in the long terminal repeat of an acquired mouse mammary tumor virus provirus in a t-cell leukemia of dba/2 mice. | ml, a transplantable t-cell leukemia of dba/2 mice, expresses the gag and env gene products of the murine mammary tumor virus (mumtv). analysis of the genomic dna of ml cells using the restriction enzyme hindiii and hybridization with mumtv-specific probes revealed that the ml cells contained two or more newly integrated mumtv proviruses (ml-mumtv). further analysis of these proviruses with a combination of mspl and pstl enzymes showed that the long terminal repeat (ltr) (ml-mumtv ltr) of the ml ... | 1987 | 3037782 |
| n-methyl-n'-nitro-n-nitrosoguanidine and benzo[a]pyrene-7,8-diol-9,10-epoxide inhibit glucocorticoid-inducible polyoma virus middle-t gene expression in rat mt-1 cells by a post-transcriptional mechanism. | treatment of rat mt-1 cells with n-methyl-n'-nitro-n-nitrosoguanidine (mnng) and benzo[a]pyrene-7,8-diol-9,10-epoxide (bpde) inhibited the steroid-induced expression of the polyoma virus middle-t (mt) gene. rat mt-1 cells were derived from normal f111 fibroblasts transfected with a plasmid (psvm-mt) containing a mt cdna sequence linked to the mouse mammary tumor virus long terminal repeat, thus rendering the mt gene responsive to glucocorticoid hormones. following a 1-h treatment period with eit ... | 1987 | 3038361 |
| interaction of the tggca-binding protein with upstream sequences is required for efficient transcription of mouse mammary tumor virus. | a high-affinity binding site for the tggca-binding protein, also known as nuclear factor i, has previously been shown to reside within the mouse mammary tumor virus (mmtv) long terminal repeat. we have introduced mutations into this binding site to test the importance of this ubiquitous nuclear protein in mmtv transcription. mutations which abolish the binding of the tggca protein in vitro are shown to impair strongly glucocorticoid-induced transcription from this promoter in vivo. these data de ... | 1987 | 3038519 |
| inheritance of a mutant histocompatibility gene and a new mammary tumor virus genome in the b6.kh-84 mouse strain. | the potential association between integration or deletion of mouse mammary tumor virus (mmtv) retroviral sequences and the appearance of non-h-2 histocompatibility (h) antigen mutations was investigated. genomic blots from inbred strains carrying 22 loss, gain-loss, and gain mutations on the balb/c and c57bl/6 backgrounds were hybridized with probes homologous to the long terminal repeat (ltr) and envelope (env) regions of mmtv. twenty-one mutants were identical in restriction patterns to the re ... | 1987 | 3038740 |
| age related differences in immunocompetence and incidence of mammary adenocarcinoma in murine mammary tumor virus-infected c3h/bi mice. | in breeder c3h/bi female mice, infected neonatally by murine mammary tumor virus (mtv), the incidence of spontaneous mammary tumors is greater than 95% between 5 and 9 months of age. in young (2-3 months) female the probability for developing a tumor in the next month is negligible, higher than 80% in mice of middle age (5-6 months) but lower than 4% in aged (10-12 months) females. the age-related changes of some immune functions of spleen cells from these tumor free female mice have been evalua ... | 1987 | 3039263 |
| rapid and selective alterations in the expression of cellular genes accompany conditional transcription of ha-v-ras in nih 3t3 cells. | hormone treatment of nih 3t3 cells that contain recombinant fusions between the mouse mammary virus long terminal repeat and the v-ras gene of harvey murine sarcoma virus results in conditional expression of the ras p21 gene product. levels of ras mrna and p21 are maximal after 2 to 4 h of hormone treatment. analysis of cellular rna by northern blotting and nuclease s1 protection assays indicates that the expression of two cellular rna species increases with kinetics similar to v-ras: v-sis-rela ... | 1987 | 3039349 |
| effects of cytoskeletal disrupting agents on mouse mammary tumor virus replication. | alterations in mouse mammary tumor virus (mmtv) production and composition were induced by exposure of mammary tumor cells to cytodisruptive agents. treatment with 2.1 microm cytochalasin d (cd) for 24 h reduced mmtv yield by 80% and electron microscopic examination of these cells did not reveal budding virions. immune precipitation and quantitative immunofluorescence studies demonstrated that cd had no significant effect on mmtv polypeptide synthesis or surface expression suggesting that cd inh ... | 1987 | 3039751 |
| genetic resistance to mammary tumorigenesis in a mouse strain with high murine mammary tumor virus expression. | although ii-tes mice release large amounts of murine mammary tumor virus (mmtv) in milk, they are resistant to mammary tumorigenesis. high mammary tumor incidence was observed in (balb/ca x ii-tes)f1 and (c57bl/6n x ii-tes)f1, whereas no mammary tumors developed in balb/ca x oz-f)f1. mammary tumors developed in 68% of (oz-f x (oz-f x ii-tes)f1 and 45% of (ii-tes x (oz-f x ii-tes)f1). these results suggest that the ii-tes mouse carries a recessive gene for mammary tumor resistance which does not ... | 1987 | 3040224 |
| interactions between a dna-binding transcription factor (coup) and a non-dna binding factor (s300-ii). | we have identified previously two transcription factors, coup (chicken ovalbumin upstream promoter) and s300-ii, from hela cell nuclear extracts. in this paper, the purine base and the phosphate backbone contact sites for the coup transcription factor were defined. these studies indicate that the coup box transcription factor interacts with specific base residues in the major groove of the dna helix. in addition, we have purified the s300-ii factor over 100,000-fold. the polypeptide possessing f ... | 1987 | 3040258 |
| mhc-controlled susceptibility to c3h-mtv-induced mouse mammary tumors is predominantly systemic rather than local. | the major histocompatibility complex (mhc) is one of the genetic factors involved in the control of susceptibility to mtv-induced mammary tumors in mice. previously, genetic differences in mammary tumor susceptibility were shown to be mainly due to differences in susceptibility of the mammary gland itself. such experiments, however, were carried out using inbred strains which differ in many genes. therefore, the conclusion drawn from such experiments is not necessarily applicable to every gene i ... | 1987 | 3040602 |