| processing and amino acid sequence analysis of the mouse mammary tumor virus env gene product. | the envelope proteins of mouse mammary tumor virus (mmtv) are synthesized from a subgenomic 24s mrna as a 75,000-dalton glycosylated precursor polyprotein which is eventually processed to the mature glycoproteins gp52 and gp36. in vivo synthesis of this env precursor in the presence of the core glycosylation inhibitor tunicamycin yielded a precursor of approximately 61,000 daltons (p61env). however, a 67,000-dalton protein (p67env) was obtained from cell-free translation with the mmtv 24s mrna a ... | 1982 | 6281457 |
| mouse mammary tumor virus dna sequences in tumorigenic and nontumorigenic cells from a mammary adenocarcinoma. | | 1982 | 6281965 |
| retroviruses in feral mice. | | 1982 | 6282773 |
| circulating immune complexes, antigens, and antibodies related to the murine mammary tumor virus in c3h mice. | | 1982 | 6282972 |
| detection of acquired provirus sequences in mammary tumors from low-expressor, low-risk mice. | murine mammary tumor virus (mumtv) provirus sequences in the dna from early-occurring (average age 10 mo) and late occurring (age greater than 20 mo) tumors in balb/cfc3h mice were analyzed by eco ri restriction endonuclease mapping procedures. all early tumors were mumtv antigen-positive mammary adenocarcinomas that contained the 0.92- and 4.0-kilo base (kb) exogenous c3h mumtv-specific pst i restriction endonuclease fragments. all but 1 of the late mammary adenocarcinomas had mumtv antigens de ... | 1982 | 6283224 |
| cell-mediated immunity to mouse mammary tumor virus antigens by patients with hyperplastic benign breast disease. | peripheral blood leukocytes of patients with preoperative breast cancer, benign breast disease, and benign gynecologic disorders and normal healthy females were tested, as blind coded specimens, with murine mammary tumor virus (mumtv) antigens in the direct and indirect leukocyte migration inhibition (lmi) assays. the incidence of reactivity by patients with breast cancer was low. (from 5 to 35% breast cancer patients reacted, depending on which group of control individuals they were compared to ... | 1982 | 6283226 |
| possible related risks to breastfeeding. | animal studies have identified a mouse mammary tumor agent transmitted through lactation that increases the incidence and reduces the age for tumor development in offspring. a similar viral particle has been detected with greater frequency in the milk of humans with a family history of breast carcinoma than in the milk of those with no history. animal studies also indicate that a male offspring who has been breastfed, at low risk himself, could possibly transmit the agent through seminal fluid. ... | 1982 | 6283228 |
| separation of high mammary tumor incidence from high hepatoma incidence in backcross mice during segregation of the viable yellow gene. | | 1982 | 6284658 |
| suppression of spontaneous mammary tumorigenesis despite mtv-1 gene expression in hybrid and backcross c3h-avyfb x c3h/sm mice. | | 1982 | 6284659 |
| methylation and amplification of mouse mammary tumor virus dna in normal, premalignant, and malignant cells of gr/a mice. | the methylation and amplification of mouse mammary tumor virus (mumtv) proviral dna was investigated in normal, premalignant, and malignant tissues of gr/a mice. the proviral methylation pattern was examined with the restriction enzyme hhai, which fails to cleave methylated dna. mumtv proviral dna from liver, kidney, and heart was highly methylated. proviral dna was somewhat undermethylated in mammary gland cells from virgin and lactating mice and extensively undermethylated in cells from premal ... | 1982 | 6284957 |
| dna sequence relationship of the baboon endogenous virus genome to the genomes of other type c and type d retroviruses. | baboon endogenous virus (baev) is a type c retrovirus present in multiple proviral copies in the dna of baboons. although interspecies antigenic determinants present on reverse transcriptase and gag proteins are shared among all mammalian type c viruses, no nucleic acid homology between baev and other type c viruses (except rd-114) has been found in conventional liquid hybridization experiments. in this study, we used restriction fragments of cloned baev dna immobilized on nitrocellulose to test ... | 1982 | 6284972 |
| restriction endonuclease mapping of the proviral dna of the exogenous riii murine mammary tumor virus. | cellular dna containing integrated murine mammary tumor virus (mumtv) was isolated from fei/c6 feline kidney cells and ccl64 mink lung cells infected with milkborne riii mumtv. by using restriction enzyme hpai, intact riii mumtv provirus (length, 8.7 kilobases [kb]) was excised from the cellular dna. subsequent restriction endonuclease analysis of this hpai fragment with kpni, hindiii, ecori, bamhi, bglii, psti, ssti, sali, and xhoi enabled us to construct a map of the riii virus genome. a compa ... | 1982 | 6284976 |
| conservation of protein coding potential in the long terminal repeats of exogenous and endogenous mouse mammary tumor viruses. | in vitro protein synthesis and dna sequence analysis indicate that mouse mammary tumor virus differs from other well-characterized retroviruses in that the long terminal repeat region of the provirus has the capacity to encode proteins. different exogenously transmitted mouse mammary tumor virus strains and endogenous proviral units conserved this open reading frame feature in the long terminal repeat despite a variation in nucleotide sequence. the proteins encoded by the different long terminal ... | 1982 | 6285002 |
| identification of an antigen associated with transforming genes of human and mouse mammary carcinomas. | sera from tumor-bearing mice immunoprecipitated a 86,000-dalton glycoprotein from extracts of nih cells transformed by human mammary carcinoma dna. this antigen was not immunoprecipitated from extracts of nih 3t3 cells, spontaneously transformed nih cells, nih cells transformed by normal human dna, nih cells transformed by human bladder carcinoma dna, or nih cells transformed by rous sarcoma virus dna. in addition, sera from mice bearing tumors induced by nih cells transformed by either normal h ... | 1982 | 6285346 |
| sera from breast cancer patients contain an iga antibody to a breast cyst fluid component. | | 1982 | 6286196 |
| radioimmunoassay for major external glycoprotein of murine mammary tumor virus. | | 1982 | 6286471 |
| identification of a unique mouse mammary tumor virus in the balb/cniv mouse strain. | we examined the genetic structure, in terms of restriction endonuclease recognition sites, of the milk-transmitted, low-oncogenic mouse mammary tumor virus (mumtv) of the balb/cniv mouse strain. an analysis with ecori documented the presence of acquired cniv proviruses in the mammary tumor dnas of balb/cniv animals. a comparison of tumor dnas digested with psti showed that both the cniv mumtv and c3hf mumtv proviruses lacked the 4.3- and 1.1-kilobase pair fragments characteristic of c3h mumtv pa ... | 1982 | 6286994 |
| a high-tumor-incidence subline of the d1 mouse mammary hyperplastic outgrowth line: effect of carcinogens. | mammary tumorigenesis in some mouse strains is characterized by the appearance of a preneoplastic lesion, the hyperplastic alveolar nodule (han). the biology of the han has been characterized primarily through the study of stable outgrowth lines of serially transplanted han. one outgrowth line, dl, which was developed and carried in female balb/c mice, has been described as a low-tumor-incidence line that does not express murine mammary tumor virus (mumtv) and is susceptible to hormonal, chemica ... | 1982 | 6287083 |
| comparison of mammary tumorigenesis between litters in relation to mammary tumor virus antigenic expression in the milk of c3h/he mice. | as a possible step to estimate the relationship between mammary tumor virus (mtv) and mammary tumorigenesis in mice, mtv antigenic expression in mother's milk and spontaneous mammary tumorigenesis in their daughters were compared between the 1st, the 2nd and the 3rd litters of the highly inbred strains of c3h/h3 mice with low mammary tumor incidence. while mtv antigenic expression was detected in all undiluted samples at each litter by immunodiffusion test, the amount of antigen as measured by t ... | 1982 | 6287151 |
| novel class of mouse mammary tumor virus-related dna sequences found in all species of mus, including mice lacking the virus proviral genome. | mice in breeding colonies of feral mus musculus brevirostris (azrou, morocco), m. m. musculus (studenec, czechoslovakia), and m. m. molossinus (fukuoka, japan) were found to lack the mouse mammary tumor virus (mmtv-alpha) proviral genome in their germ line. mmtv-alpha proviral genomes have been found in all inbred strains of m. musculus by using high-stringency nucleic acid hybridization conditions. we conclude that feral mice in these colonies are heterozygous for a limited number of mmtv-alpha ... | 1982 | 6287466 |
| dna mediated transfer and fate of a proviral gene of mouse mammary tumor virus in cultured cells. | | 1982 | 6287482 |
| chromosomal position effects determine transcriptional potential of integrated mammary tumor virus dna. | | 1982 | 6288960 |
| [cross-reaction of human breast cancers with the envelope glycoprotein gp 52 of the mouse mamma tumorvirus (mmtv)]. | | 1981 | 6289552 |
| [electron microscopical observations of the junctional elements in virus-producing murine mammary tumors]. | | 1981 | 6289553 |
| simple sandwich enzyme immunoassay for quantification of mouse mammary tumor virus in mouse milk. | we have developed a sandwich enzyme immunoassay in order to measure quantitatively mouse mammary tumor virus (mmtv) in mouse milk. in this assay, the antibody-beta-d-galactosidase complex and antibody-bound silicon rubber pieces pieces as solid phase are used. the assay is able to detect 10 ng/ml of mmtv in the milk sample. | 1982 | 6290029 |
| heterogeneity of expression and induction of mouse mammary tumor virus antigens in mouse mammary tumors. | seven spontaneous balb/cfc3h mouse mammary tumors were heterogeneous in expression of murine mammary tumor virus-associated cell surface antigens. to determine the basis of this heterogeneity, cells from spontaneous tumors and from five subpopulations isolated from a single spontaneous tumor were examined for expression of viral antigens under both conventional conditions and conditions known to induce synthesis of murine mammary tumor virus antigens (5-iodo-2'-deoxyuridine and dexamethasone). i ... | 1982 | 6290031 |
| strain-specific differences of the major structural proteins of murine mammary tumour virus. | | 1982 | 6290376 |
| accelerated appearance of chemically induced mammary carcinomas in obese yellow (avy/a) (balb/c x vy) f1 hybrid mice. | latent periods and cumulative incidence of mammary carcinomas (mt) up to 50 wk after initial gavage with 7.12-dimethylbenz[a]anthracene (dmba) were determined in virgin yellow (avy/a) and agouti (a/a) (balb/cstcrlfc3hf/nctr x vy/wffc3hf/nctr-avy) f1 hybrid female mice. when subcutaneous masses reached 5-10 mm in diameter, the mice were killed and necropsied, and the tissues examined histologically. no mt were found in control mice. cumulative mt incidence in the 1.5-mg dmba group (a) was 43% (41 ... | 1982 | 6290678 |
| purified glucocorticoid receptor-hormone complex from rat liver cytosol binds specifically to cloned mouse mammary tumor virus long terminal repeats in vitro. | purified glucocorticoid hormone-receptor complex (hrc) from rat liver binds to specific dna sequences contained in cloned mouse mammary tumor virus (mmtv)dna. the binding site of the hormone-receptor complex is located in the long terminal repeat (ltr) of mmtv dna as shown by filter binding studies with labeled restriction fragments and by visualization of dna-receptor complexes with the electron microscope. the dnas from cloned mmtv lacking the ltr sequences were neither retained on nitrocellul ... | 1982 | 6291027 |
| detection and cloning of human dna sequences related to the mouse mammary tumor virus genome. | sequences related to the mouse mammary tumor virus (mmtv) genome have been detected in fragments of restricted human cellular dna. these results were obtained by using recombinant dna containing the mmtv proviral genome and lowering the stringency of blot-hybridization conditions. the mmtv genome also reacts with unique families of fragments in restricted cellular dna from other mammalian species but not with salmon sperm dna. a clone that reacted with labeled mmtv proviral dna was selected from ... | 1982 | 6291047 |
| relationships between morphology and viral etiology in mammary tumors of balb/cfc3h and balb/cfriii mice. | the morphologic pattern of mammary tumors induced by milk-transmitted c3h and riii murine mammary tumor viruses (mumtvs) in balb/c hosts infected by foster nursing were investigated further an compared taking into account several tumor and host variables. comparison of balb/cfc3h and balb/cfriii mammary tumors under identical tumor and host conditions showed highly significant differences in subgross morphology and histologic structure. differences in cytology were also observed. data suggest th ... | 1982 | 6291203 |
| antibody reacting with the murine mammary tumor virus in the serum of patients with breast carcinoma: a possible serological detection method for breast carcinoma. | sera from patients with stages a and b infiltrating ductal carcinoma of the breast, benign breast disease, cancers other than breast carcinoma, and normal female controls were examined by indirect immunoelectron microscopy (iem) and a viral agglutination test for evidence of antibodies directed against murine mammary tumor virus (mmtv). sera from 41 (79%) of 52 patients with breast carcinoma and eight (19%) of 42 normal subjects or patients with benign breast disease (noncancer subjects) showed ... | 1983 | 6291754 |
| mumtv antigen expression and mammary tumor incidence in non-inbred dd mice. | the expression of mammary tumor virus (mtv) antigen in the milk and various organs of three non-inbred dd mouse stocks (ddo, ddn and ddy) was examined by the immunodiffusion (id) and micro-immunodiffusion (micro-id) tests. the rate of mtv antigen expression in the milk was 100% at the first lactation in ddo (6/6) and ddn mice (10/10), and 23% in ddy mice (3/13). mammary tumor incidence was 13% (mean tumor age: 12.0 months), 32% (9.6 months) and 10% (11.5 months) in ddo, ddn and ddy mice, respect ... | 1982 | 6291954 |
| mouse mammary tumour virus and polyoma virus information in mammary tumours of athymic mice inoculated with polyoma virus. | polyoma virus inoculation of athymic mice results in the development of mammary tumours with a much higher incidence than the development of salivary gland tumours, the latter being the most common for immunocompetent normal mice. the possibility existed that polyoma virus might act as a co-carcinogen in activating the expression of mouse mammary tumour virus (mmtv). molecular hybridization studies, however, showed that the mammary tumour development was accompanied by neither the amplification ... | 1982 | 6292336 |
| in situ hybridization: general infectivity assay for retroviruses. | we have devised a general infectivity assay for retroviruses. a virus-specific [32p]dna probe is hybridized in situ to a monolayer culture, and foci of infected cells in the monolayer are detected by exposure of the hybridized culture to x-ray films. the method is quantitative, in that it gives the same titer for moloney murine leukemia virus as does the standard uv-xc test. the specificity of the assay is indicated by the fact that murine leukemia virus and baboon endogenous virus do not cross ... | 1982 | 6292448 |
| acquisition of proviral dna of mouse mammary tumor virus in thymic leukemia cells from gr mice. | male mice of strain gr develop t-cell leukemia at a low frequency late in life. these leukemia cells contain large amounts of mouse mammary tumor virus (mmtv) rna and mmtv proteins in a precursor form (nusse et al., j. virol. 32:251-258, 1979). we used restriction enzyme analysis and molecular hybridization to identify mmtv proviruses in the dna of these leukemia cells. gr leukemia cells contained additional integrated mmtv proviruses at various sites in the genome. this amplification of mmtv pr ... | 1982 | 6292463 |
| mouse mammary tumor virus proviral sequences congenital to c3h/sm mice are differentially hypomethylated in chemically induced, virus-induced, and spontaneous mammary tumors. | c3h/sm mice have lost the exogenous milk-borne mouse mammary tumor virus (mmtv) characteristic of the c3h strain and have a very low (1.5%) incidence of spontaneous mammary tumors, yet they are highly susceptible to mammary carcinogenesis by either chemical carcinogens or infection with the milk-borne virus. we have analyzed the mmtv proviral dna content of normal tissues and of spontaneous, virus-induced, and chemically induced mammary tumors by restriction endonuclease digestion and southern b ... | 1982 | 6292467 |
| analysis of lymphoid cells responding to virus- and tumor-associated antigens in spleens of syngeneic mouse mammary tumor systems with low and high oncogenic potentials. | | 1982 | 6292565 |
| glucocorticoid regulation of protein processing and compartmentalization. | | 1982 | 6292722 |
| natural and induced immunity to mouse mammary tumors and the mammary tumor virus (mumtv). | | 1982 | 6293110 |
| cloned endogenous mouse mammary tumor virus dna is biologically active in transfected mouse cells and its expression is stimulated by glucocorticoid hormones. | | 1982 | 6293178 |
| development of a mouse mammary tumor virus-negative mouse strain: a new system for the study of mammary carcinogenesis. | all inbred strains of mice transmit one or more copies of mouse mammary tumor virus (mmtv) dna integrated as proviral sequences. this complicates efforts to define viral-induced mammary carcinogenesis. here we report the use of surgical nonlethal splenectomy in tissue typing mice and the development of an mmtv-negative mouse strain. the mmtv-negative strain allows study of the involvement of non-mmtv genes in mammary carcinogenesis. in addition, it can be used as a sterile background into which ... | 1982 | 6294336 |
| mammary tumors in balb/cfc3h and balb/cfriii virgin female mice bearing hypophyseal isografts. | the behavior and morphology of mouse mammary tumors in high cancer strain mice are controlled by the causative murine mammary tumor viruses (mumtv). however, relationships also exist between mammary tumors and other factors such as host genotype, other etiologic agents (chemicals, x-rays), and hormones. among the latter, prolactin has been particularly studied. the aim of this investigation was to test whether the mammary tumor morphology controlled by c3h and riii mumtvs is in any way influence ... | 1982 | 6294936 |
| murine mammary tumor virus related antigen in human male mammary carcinoma. | an antigen immunologically related to mouse mammary tumor virus (mumtv) and the major envelope glycoprotein, gp52 of mumtv, was identified in tissue sections of human male and female mammary carcinomas using the peroxidase-antiperoxidase technique. the specificity of the reaction was established by absorption studies. positive reactions with the gp52 antiserum were seen in mouse and human mammary carcinomas, but not in normal mammary tissues, mammary tissues with benign diseases and in other pri ... | 1983 | 6295611 |
| chemical carcinogen-mouse mammary tumor virus interactions in cell transformation. | we have studied the process of mammary cell transformation in vitro using a single cell clone (clone 18) from a presumptive epithelial cell line, c57mg, derived from a normal mammary gland; a mouse mammary tumor virus (mmtv) host-range variant (riii)vp4; and the potent initiating carcinogen 7,12-dimethylbenz(a)anthracene (dmba). after several serial subcultures, cells treated with virus and then with carcinogen exhibited an altered (transformed) morphology, a dramatic increase in anchorage indep ... | 1983 | 6295922 |
| multiple specific binding sites for purified glucocorticoid receptors on mammary tumor virus dna. | glucocorticoid hormones selectively stimulate the rate of transcription of integrated mammary tumor virus (mtv) sequences in infected rat hepatoma cells. using two independent assays, we find that purified rat liver glucocorticoid receptor protein binds specifically to at least four widely separated regions on pure mtv proviral dna. one of these specific binding domains, which itself contains at least two distinct receptor binding sites, resides within a fragment of viral dna that maps 110-449 b ... | 1982 | 6296168 |
| unconventional application of standard light and electron immunocytochemical analysis to aldehyde-fixed, araldite-embedded tissues. | a simple procedure for the immunocytochemical analysis of glutaraldehyde/formaldehyde-fixed, araldite- or epon-embedded tissues by either light or electron microscopy is presented. retention of immunoreactive antigen in deplasticized sections was achieved by use of a low concentration of glutaraldehyde in the fixative in combination with a seldom-used plastic solvent. this protocol produced good ultrastructural preservation in tissues and large, high-quality, 2-micrometers thick, plastic-free se ... | 1982 | 6296221 |
| integration of new endogenous mouse mammary tumor virus proviral dna at common sites in the dna of mammary tumors of c3hf mice and hypomethylation of the endogenous mouse mammary tumor virus proviral dna in c3hf mammary tumors and spleens. | to understand the molecular mechanisms by which the endogenous murine mammary tumor virus (mumtv) proviruses are expressed and produce late-occurring mammary tumors in c3hf mice, we analyzed, by the use of restriction enzymes and the southern transfer procedure, genomic dna from normal organs of mammary tumor-bearing and tumor-free mice and from 12 late-occurring c3hf mammary tumors. we found, by using the restriction enzymes ecori and hindiii, that in addition to the preexisting endogenous mumt ... | 1983 | 6296426 |
| identification of a cellular receptor for mouse mammary tumor virus and mapping of its gene to chromosome 16. | pseudotypes of vesicular stomatitis virus (vsv) containing envelope glycoproteins provided by c3h mammary tumor virus (mtv) instead of the normal vsv g-proteins were prepared and used to assay the presence of an mtv receptor on cells. the assay was specific as demonstrated by competition studies with excess mtv particles and neutralization of the pseudotypes with anti-mtv serum or monoclonal antibodies directed against mtv gp52. the mtv receptor was abundantly present on mouse cells but hardly d ... | 1983 | 6296428 |
| cloned mouse mammary tumor virus dna exhibits glucocorticoid-dependent expression in simian virus 40-transformed mink cells. | mink lung epithelial cells were transfected with two cloned mouse mammary tumor virus (mmtv) dnas, a 9-kilobase clone derived from an unintegrated exogenous viral genome and a 14-kilobase clone containing an integrated endogenous provirus along with cellular flanking sequences. mink lung cells were chosen because they do not contain endogenous mmtv sequences. on the basis of our observation that simian virus 40 dna efficiently transforms these cells, we isolated cell clones containing mmtv dna b ... | 1983 | 6296429 |
| low-calorie diet prevents the development of mammary tumors in c3h mice and reduces circulating prolactin level, murine mammary tumor virus expression, and proliferation of mammary alveolar cells. | the effect of carlorie intake on the development of spontaneous mammary tumors in virgin c3h mice was studied. only about 10% of the mice fed a low-calorie diet [10 kcal/day (1 kcal = 4.184 kj)] since weaning developed mammary tumors, compared to about 60% of those mice that were reared on high-calorie diets (16 kcal/day or lab chow ad lib). in order to understand the mechanism by which a low-calorie diet decreases the occurrence of mammary tumors in mice, we compared the sex cycle, the amounts ... | 1982 | 6296850 |
| demethylation and expression of murine mammary tumor proviruses in mouse thymoma cell lines. | murine mammary tumor virus (mmtv) expression is analyzed in a t-lymphoid cell line (t1m1) sensitive to the killing effect of glucocorticoids and in two of its variants, one resistant (t1m1r) and one supersensitive (t1m1ss) to glucocorticoid-induced lymphocytolysis. in the t1m1 line, mmtv is expressed and induced approximately 10-fold by short treatment with dexamethasone. southern blot analyses of restriction enzyme digests of dna from t1m1 cells reveal three proviruses similar to those of norma ... | 1983 | 6296860 |
| prostaglandin regulation of murine mammary tumor virus production: a basis for some of the glucocorticoid and prolactin actions on mammary tumor cell cultures. | hormonal regulation of mouse mammary tumor virus (mumtv) production has been studied in cell cultures derived from mammary carcinomas of gr mice. the purpose of this study was to define the role of prolactin in dexamethasone-induced mumtv production and to evaluate the mechanism(s) of action of these hormones. results of our investigations in vitro establish a central role for prostaglandins, in particular pgf2 alpha. prolactin treatment up to 1000 ng/ml increased the mumtv production only sligh ... | 1982 | 6296884 |
| interaction between host and viral genomes in mouse mammary tumors. | | 1982 | 6297374 |
| kinetics of the reactivity of subpopulations of spleen cells of mice bearing virus-induced mammary tumors to syngeneic antigenic extracts in vitro. supportive and suppressive effects of macrophages. | this study was designed to investigate the nature of lymphocyte reactivity to soluble tumor antigens with respect to the kinetics of the reactivity, the responding cell type, and the role of accessory cells, within a syngeneic system. balb/c mice were inoculated with 1 x 10(6) viable cells of syngeneic mtv-induced mammary tumors. assessment of proliferative activity of spleen cells of these animals by dna synthesis (3h-thymidine incorporation in vitro) indicated a biphasic response to stimulatio ... | 1982 | 6297714 |
| many tumors induced by the mouse mammary tumor virus contain a provirus integrated in the same region of the host genome. | we have asked whether oncogenesis by the mouse mammary tumor virus (mmtv), a slowly oncogenic retrovirus, involves integration of viral dna within a certain region of the host genome. we first identified a c3h mouse mammary tumor bearing a single new mmtv provirus and cloned a 19 kilobase (kb) dna restriction fragment containing a junction of viral and host sequences. host sequences from this clone were used to retrieve 25 kb of the uninterrupted locus (termed mmtv int1) from a bacteriophage lib ... | 1982 | 6297757 |
| specific binding of the glucocorticoid-receptor complex to the mouse mammary tumor proviral promoter region. | to elucidate the molecular mechanism by which steroid hormones exert their regulatory function, we investigated the interaction of a glucocorticoid-receptor complex with purified dna fragments from cloned mouse mammary tumor (mmtv) proviral dna. with a dna-cellulose binding assay, rat and mouse glucocorticoid receptors were found to interact with a high affinity site or sites in or near the promoter region of the mmtv proviral dna. the assay allowed the use of unpurified as well as purified rece ... | 1982 | 6297768 |
| effect of hormones on the expression of proviral genes mtv-2 and mtv-3 in mouse mammary gland. | we have investigated the expression of the mtv-2 and mtv-3 proviral genes in mouse mammary glands by examining the effect of hormones on levels of mammary tumor virus (mtv) proteins p27 (gag) and gp52 (env) in mouse mammary explants. we also investigated the effect of the hormones on dna synthesis in the explants. the mammary glands were derived from inbred gr and 020 mice, and from the respective congenic mouse strains gr/mtv-2- and 020/mtv-2+. the addition of insulin to the culture medium caus ... | 1983 | 6298127 |
| region-specific initiation of mouse mammary tumor virus rna synthesis by endogenous rna polymerase ii in preparations of cell nuclei. | adenosine 5'-o-(2-thiotriphosphate) (atp beta s) and guanosine 5'-o-(2-thiotriphosphate) (gtp beta s) were used to demonstrate initiation of mouse mammary tumor virus (mmtv) rna in preparations of whole nuclei from control and glucocorticoid-treated mmtv-infected rat hepatoma tissue culture cells. rna chains initiated in the cell-free reaction retain a thiol group at the 5' end and can be separated from thiol-free rna chains by chromatography on mercury-sepharose. the abundance of mmtv sequences ... | 1983 | 6298206 |
| the correlation between tissue differentiation and production of mammary tumor virus (mtv) in transplanted murine mammary tumors. electron microscopic observations. | the spontaneous mammary tumors of the nmri mouse are well developed microcystic adenocarcinomas. serial isologous transplantation of the tumors results in nearly complete dedifferentiation to a solid tumor, in which only electron-microscopically rudimentary acinus-like microlumina can be observed. the adenocarcinomas produce a and b particles in abundance, with the a particles appearing intracellularly in the adluminal cytoplasmic regions of the epithelial cells in association with typical cellu ... | 1983 | 6298246 |
| a deletion mutant of mouse mammary tumour virus, lacking 516 nucleotides of the 5' long terminal repeat sequence, can be expressed in a hormone-responsive fashion. | in vitro manipulation of proviral dna of mouse mammary tumour virus (mmtv) was used to construct mutants with defined deletions at the 5' end of the proviral gene. in the mutants 516, 1400 and 2000 nucleotides were removed from the 5' end. the deleted proviral dna was tested for transcription and glucorticoid hormone regulation of viral rna expression upon cotransfection into rat xc tk- cells with a thymidine kinase gene. intact proviral dna contained in the plasmid vector pbr322 and the deletio ... | 1983 | 6298347 |
| transcription of mouse mammary tumor virus: identification of a candidate mrna for the long terminal repeat gene product. | we have examined an assortment of preneoplastic and neoplastic mouse mammary tissues for the presence of an mrna which could encode the putative long terminal repeat gene product of mouse mammary tumor virus. we report here the detection of a novel mouse mammary tumor virus-specific, polyadenylic acid-containing transcript in certain preneoplastic and neoplastic mammary tissue of balb/c mice. the molecule is 1.6 kilobases in length and contains sequences from the transcriptional leader and the u ... | 1983 | 6298469 |
| a comparison of nucleoside (beta-s)triphosphates and nucleoside (gamma-s)triphosphates as suitable substrates for measuring transcription initiation in preparations of cell nuclei. | rna chains initiated with nucleoside (beta-s)triphosphates and (gamma-s)triphosphates retain the thiol groups and can be separated from thiol-free rna by chromatography on mercury-sepharose. thiol-containing mouse mammary tumor virus (mmtv) rna synthesized by preparations of nuclei from virus-infected cells was quantitated by nucleic acid filter hybridization. with atp beta s and gtp beta s, region-specific initiation of mmtv rna chains was detected in the cell free system. however, with atp gam ... | 1982 | 6298716 |
| leukocyte migration inhibition responses to mcf-7, murine mammary tumor virus, and thomsen-friedenreich antigen in a series of cancer patients. | | 1983 | 6299532 |
| complementary dna copies of leukemia and sarcoma virus rna contain sequences of deoxycytidylate and deoxyguanylate. | single-stranded complementary dna (cdna) of the rna of gazdar murine sarcoma virus, gz-msv/mulv; moloney murine leukemia virus, m-mulv; mouse mammary tumor virus, mmtv; and simian sarcoma virus, ssv-1, were synthesized in endogenous reverse transcriptase reaction. gz-msv/mulv cdna was also synthesized in exogenous in vitro reverse transcriptase reactions. in the endogenous reaction, 30-35s, or 6.0- to 7.9-kilobase-length cdna transcripts were synthesized in high yield. in comparison, transcripts ... | 1981 | 6299564 |
| a viral antigen as a marker for the prognosis of human breast cancer. | an antigen present in human breast tumor cells, and which is immunologically related to the envelope protein (gp52) of murine mammary tumor virus, was used as a marker for the detection of breast cancer in an israeli population. the results show that the antigen was detectable in 128 of 204 breast carcinomas tested (62.7%). the immunological reaction was not detected in normal breast tissue, benign breast tumors, ductal hyperplasia or in primary malignancies in other organs. a significantly high ... | 1982 | 6299750 |
| an antigen cross-reactive with gp52 of mammary tumor virus is expressed on a b cell subpopulation of mice. | the reactivity of murine lymphoid tissue with biotinylated f(ab')2 fragments of monoclonal antibody ve7 (biot ve7), which reacts with gp52 of murine mammary tumor virus (mumtv), was tested with fluoresceinated avidin in an indirect fluorescent antibody assay on live splenocytes. a small percentage of splenic lymphocytes in c3h/he mice infected exogenously with mumtv, and in c57bl/6 mice that, like c3h/he, harbor several endogenous mumtv proviruses in their genomes, were reactive with the monoclo ... | 1983 | 6300244 |
| further evidence for the protein coding potential of the mouse mammary tumor virus long terminal repeat: nucleotide sequence of an endogenous proviral long terminal repeat. | the 3' half of an endogenous mouse mammary tumor virus from a c3h mouse was cloned in the charon 4a vector phage. a comparison of the proviral clone with previously published endogenous mouse mammary tumor virus restriction maps identified it as endogenous unit ii (j. cohen and h. varmus, nature [london] 278:418-423, 1979), which is present in all inbred mouse strains derived from the original bagg albino x dba cross. the nucleotide sequence of the unit ii long terminal redundancy (ltr) was dete ... | 1983 | 6300464 |
| atmospheric pressure effects on tumor growth: hypobaric anoxia and growth of a murine transplantable tumor. | inasmuch as solid tumor growth and some intervention methods for tumor control have often been related to the low oxygen levels in tumor tissue, and a special role for hypoxia, perhaps even in oncogenesis, has been suggested by observations of unexpectedly low tumor incidence in mice caged a lifetime in the environment of a simulated altitude, inbred c3h/hen mammary tumor virus-positive mice bearing transplanted tumors (16/c murine mammary adenocarcinoma) were exposed to atmospheric pressure var ... | 1983 | 6300503 |
| two classes of mutant mammary tumor virus-infected htc cell with defects in glucocorticoid-regulated gene expression. | we have isolated mutant derivatives of m1.54 (a mammary tumor virus [mtv]-infected rat hepatoma [htc] cell line containing multiple integrated proviruses) that fail to express hormone-inducible cell surface viral glycoproteins. in wild-type m1.54, the synthetic glucocorticoid dexamethasone selectively stimulates the rate of synthesis of mtv rna. in addition, dexamethasone is essential for posttranslational maturation of three of the four cell surface viral glycoproteins processed from the mtv gl ... | 1983 | 6300655 |
| signals governing mouse mammary tumor virus expression in vivo and in cultured cells upon proviral dna transfer. | | 1982 | 6300919 |
| quantitative analysis of mouse mammary tumor virus in milk in two sublines of riii/anok mice with low and high mammary tumor incidence. | mammary tumors have ceased to develop in descendants of one female of the riii/anok mouse strain which was brought from the mouse colony of okayama university medical school in 1975, while descendants of another female of this strain have maintained a high tumor incidence. the former and latter descendants were separated out as riii/anok/2 and riii/anok/1 sublines, respectively. the amount of mouse mammary tumor virus (mmtv) in the milk of individual females in these two sublines was determined ... | 1983 | 6301918 |
| expression and regulation of escherichia coli lacz gene fusions in mammalian cells. | gene fusions between the escherichia coli lacz gene and dna segments containing the simian virus 40 early promoter or the mouse mammary tumor virus (mmtv) promoter direct the synthesis of functional beta-galactosidase in cos 7 monkey cells and mouse ltk-cells. enzymatic activity was measured either 72 h after transfection or in stable transformants. the sensitive beta-galactosidase assay was used to measure gene expression and to optimize the efficiency of dna-mediated transfection. glucocortico ... | 1983 | 6302193 |
| in vivo modification of retroviral gag gene-encoded polyproteins by myristic acid. | it has recently been shown by mass spectral analysis (henderson et al., proc. natl. acad. sci. u.s.a. 80:339-343, 1983) that the p15gag protein of murine leukemia viruses contains a novel post-translational modification, an amino-terminal myristyl (tetradecanoyl) amide. in this report we show that p15gag is the only structural protein to contain this fatty acid. in addition, the gag precursor polyproteins of type b, c, and d retroviruses have been examined for the presence of myristic acid by me ... | 1983 | 6302307 |
| expression and disposition of the murine mammary tumor virus (mumtv) envelope gene products by murine mammary tumor cells. | three murine mammary tumor virus (mumtv)-producing epithelial cell lines derived from murine mammary tumors were examined in order to identify the mumtv-specific cell surface antigens and their distribution on the cell surface, to study the kinetics of the mumtv envelope precursor processing, virus assembly, and release, and to characterize the soluble mumtv antigens that are shed into culture medium. cell surface labeling experiments showed that only the mature mumtv envelope glycoproteins gp52 ... | 1983 | 6302986 |
| [is the regulation of the expression of mmtv proviruses in various cell types linked to glucocorticoid receptors and/or the structure of chromatin?]. | the expression of the mouse mammary tumor virus (mmtv) was studied in undifferentiated embryonal carcinoma cells (ec), in partially differentiated myoblasts derived from ec cells and in fully differentiated myotubes. whereas no mmtv rna could be detected in ec cells, relatively large amounts of tumor virus rna were found in myoblasts. the mmtv rna level was reduced in myotubes derived from myoblastic differenciation. dnasei sensibility of mmtv dna in chromatin allows us to show conformational ch ... | 1982 | 6303198 |
| mammary tumor formation and hormonal control of mouse mammary tumor virus expression. | | 1982 | 6303703 |
| the role of protein glycosylation in the compartmentalization and processing of mouse mammary tumor virus glycoproteins in mouse mammary tumor virus-infected rat hepatoma cells. | the relationship of protein glycosylation to compartmentalization and processing of mouse mammary tumor virus (mtv) glycoproteins has been examined in m1.54, a cloned line of mtv-infected rat hepatoma tissue culture cells. previous work established that full maturation of mtv glycoproteins in this cell line requires dexamethasone, a synthetic glucocorticoid (firestone, g. l., payvar, f., and yamamoto, k. r. (1982) nature (lond.) 300, 221-225). the ability to regulate production of the full compl ... | 1983 | 6304028 |
| regulation of endogenous murine mammary tumor virus expression in c57bl mouse lactating mammary glands: transcription of functional mrna with a block at the translational level. | expression of endogenous murine mammary tumor viruses (mumtvs) in various mouse strains is regulated in different ways, and in the absence of exogenous mumtv, this regulation influences the incidence of spontaneous mammary tumors. two mouse strains with low mammary tumor incidence, balb/c and c57bl, control endogenous mumtv expression at different stages. neither of the strains had any detectable mumtv polypeptides in its lactating mammary glands (lmg). however, in c57bl lmg, substantial amounts ... | 1983 | 6304344 |
| glucocorticoids and chromosomal position modulate murine mammary tumor virus transcription by affecting efficiency of promoter utilization. | the rate of transcription of murine mammary tumor virus (mtv) sequences in mtv-infected rat hepatoma tissue culture cells is strongly affected by both glucocorticoid hormones and the chromosomal position of provirus integration. we have characterized mtv rnas produced in j2.17 and m1.54, independent isolates containing, respectively, 1 and 10 proviruses integrated at distinct chromosomal loci. m1.54, but not j2.17, synthesized mtv rna in the absence of glucocorticoids; the rate of hormone-stimul ... | 1983 | 6304497 |
| androgen regulation of cell proliferation and expression of viral sequences in mouse mammary tumour cells. | the role of steroids in promoting cell proliferation is well established but the molecular mechanisms are not clear. the s115 mouse mammary tumour cell line provides a model system for molecular studies in vitro in that it exhibits in tissue culture both a positive proliferative response to androgens and a change from a transformed phenotype in the presence of androgen to a normal phenotype when androgen is removed. we have considered here the possible involvement of mouse mammary tumour virus ( ... | 1983 | 6304523 |
| subfragments of the large terminal repeat cause glucocorticoid-responsive expression of mouse mammary tumor virus and of an adjacent gene. | after transfection of mouse mammary tumor virus (mmtv) proviral dna into cultured cells, the dna is transcribed in a glucocorticoid-sensitive fashion. the large terminal repeat (ltr) region of mmtv is 1,328 nucleotides long and contains the regulatory information necessary for the hormonal response. we have constructed a mmtv ltr-thymidine kinase (tk) chimeric gene and have tested the biological activity of molecules containing various deletions in the ltr after transformation of ltk- aprt- mous ... | 1983 | 6304728 |
| serum antibodies against mouse mammary tumor-virus-associated antigen detected nine months before appearance of a breast carcinoma. | | 1983 | 6305248 |
| isozyme phenotypes of polyoma virus tumors in mice. | isozyme profiles for 32 enzyme systems were studied in tumors induced by two strains of polyoma virus (2pta and lid1), in two conventional mouse strains (c3h/bida and nih), and in athymic (nude) mice of two genetic backgrounds (c3h/hes nu/nu and nih nu/nu). tumors studied were: primary and transplant passages of salivary gland tumors (127); primary thymic epithelial tumors (12); primary subcutaneous sarcomas (6); primary hair follicle tumors (5); primary and transplant passages of mammary tumors ... | 1983 | 6305495 |
| tumorigenesis by mouse mammary tumor virus: evidence for a common region for provirus integration in mammary tumors. | we have prepared specific probes for unique-sequence cellular dna adjacent to each of the newly integrated proviruses in tumors induced by mouse mammary tumor virus (mmtv). the use of such probes to screen a large number of independent mammary tumors in the br6 strain of mouse has indicated that in at least 17 out of the 40 tumors examined so far, an mmtv provirus has integrated into a common chromosomal domain. a 10 kb eco ri fragment of single copy dna from this region has been isolated and pa ... | 1983 | 6305506 |
| biological activity of cloned mammary tumor virus dna fragments that bind purified glucocorticoid receptor protein in vitro. | | 1983 | 6305596 |
| mammary tumor virus. investigations in mouse and man. | | 1981 | 6305702 |
| among the human antibodies reacting with intracytoplasmic a particles of mouse mammary tumor virus, some react with mmtv p14, the nucleic-acid-binding protein, and others with mmtv p28, the main core protein. | human igg antibodies reacting in the indirect immunofluorescence test with clusters of intracytoplasmic a particles in mouse tissues were analyzed by means of both radioimmunoprecipitation and enzyme-linked immunoabsorbant assays. generally, antibody-containing sera reacted with epitopes of p14, the nucleic-acid-binding core protein of mouse mammary tumor virus, corresponding to the protein ap14 of intracytoplasmic a particles. comparatively few sera reacted with epitopes of the main core protei ... | 1983 | 6305853 |
| delimitation of a dna sequence which confers inducibility by glucocorticoid hormones. | a chimeric long terminal repeat-thymidine kinase (ltr-tk) gene has been used to define the sequence requirements for glucocorticoid induction of gene expression. the original ltr-tk gene contains an entire mouse mammary tumor virus (mmtv) ltr preceding the tk gene. this gene can be expressed in a hormone-responsive fashion upon transfection into l tk--cells to produce a chimeric ltr-tk mrna. stepwise deletion of nucleotide sequences 5' of the viral rna initiation site revealed that 202 nucleotid ... | 1982 | 6306020 |
| mouse mammary tumour virus related sequences are present in human dna. | mumtv-related sequences have been identified in the dna of human breast cancer cells using the southern transfer technique and hybridisation with cloned mumtv dna under conditions in which partially mismatched sequences form stable hybrids. hybridisation with cloned fragments of the mumtv genome showed that the gag-pol region shares the most homology (estimated to be greater than 80%) with the human mumtv-related sequences, however, dna fragments partially homologous to the mumtv ltr, gag ad env ... | 1983 | 6306576 |
| [hormone-dependent enhancement of malignant phenotype in cells infected with mouse mammary tumor virus (mmtv), and role of antigen transduction in this process]. | mouse mammary tumor virus (mmtv) is known to infect heterologous cells but it does not appear that it alters their growth or morphological characteristics. djungarian hamster mammary tumor cells infected with mmtv were found to increase the ability of the above cells to grow in semi-solid media. this effect was demonstrable only in the presence of insulin and dexamethasone in cultural media. meanwhile non-infected cells were discovered to show no responsiveness to hormones. the expression of non ... | 1983 | 6307426 |
| structural & immunological characteristics of murine mammary tumour virus of strain icrc from primary tumour cell cultures. | | 1982 | 6307861 |
| transcription initiation of transfected mouse mammary tumor virus ltr dna is regulated by glucocorticoid hormones. | a chimeric gene, recombined in vitro, containing a long terminal repeat (ltr) sequence from the proviral dna of mouse mammary tumor virus and the thymidine kinase (tk) gene of herpes simplex virus was introduced into l tk- cells. no transcription of ltr rna was observed in transfected cells when glucocorticoid hormones were absent from the growth medium. accumulation of ltr initiated rna was measured upon hormone addition by the single strand specific nuclease rna mapping procedure. the accumula ... | 1983 | 6308557 |
| tissue and organ distribution of mammary tumor virus antigens in low and high mammary cancer strain mice. | expression of mammary tumor virus (mtv) antigen was measured in a wide variety of organs and tissues of a series of high (gr, shn, shnf, dd, sln, slnf) and low (ddf, ddd, dddf, kf, kff, ddy, c57bl, balb/c) mammary cancer strain mice. tests were carried out by microimmunodiffusion (micro-id) and immunoperoxidase tests on formalin-fixed tissues and radioimmunoassays in extracts for 2 viral proteins, mtvp27 from the viral core and mtvgp52 from the viral envelope. organs with exocrine function, i.e. ... | 1983 | 6309527 |
| effects of long term exposure to beer on the genesis and development of spontaneous mammary adenocarcinoma and prolactin levels in female virgin c3h/st mice. | the exposure of female inbred virgin c3h/st mice infected with the bittner particle to a commercial brand of beer increases body weight but has no significant effects on survival, the incidence of spontaneous mammary adenocarcinoma, tumor latency, or growth even on continuous administration of beer in place of drinking water over the entire postweaning lifespan of the animals. prolactin excretion in young beer-group mice was slightly elevated but not significantly different from the prolactin le ... | 1982 | 6309941 |
| terminal amino acid sequences and proteolytic cleavage sites of mouse mammary tumor virus env gene products. | the mature envelope glycoproteins of mouse mammary tumor virus (gp52 and gp36) were isolated by reversed-phase high-pressure liquid chromatography. the n-terminal amino acid sequence of gp36 was determined for 28 residues. the c-terminal amino acid sequences of gp52 and gp36 were determined by carboxypeptidase digestion. the n-terminal amino acid sequence of gp52 has been reported previously (l. o. arthur et al., j. virol. 41:414-422, 1982). these data were aligned with the predicted amino acid ... | 1983 | 6310154 |
| a new locus (mtv-4) for endogenous mammary tumor virus expression and early mammary tumor development in the shn mouse strain. | the shn mouse strain, which has a high incidence of mammary cancer, developed by inbreeding and selection from swiss stock mice by dr. h. nagasawa and co-workers (meiji university, tokyo, japan), harbored an endogenous mammary tumor virus (mtv) responsible for a high frequency of mammary tumors early in life. the locus was called "mtv-4" and was only comparable with mtv-2 of the gr mouse strain in its inducing capacity of mammary cancer. molecular hybridization with 32p-labeled mtv complementary ... | 1983 | 6310199 |
| immunological selection of variant mouse lymphoid cells with altered glucocorticoid responsiveness. | we have devised an immunological procedure to separate cells on the basis of expression of mouse mammary tumor virus (mmtv) gene products. plastic petri dishes coated with specific antibodies against mmtv proteins bind cells with an efficiency that correlates with the level of mmtv gene expression. glucocorticoid-sensitive mouse thymoma cell line w7 was infected with mmtv. clones from the infected population retain the relatively slow cytolytic glucocorticoid response and, in addition, exhibit a ... | 1983 | 6310372 |
| enhancer elements activated by steroid hormones? | | 1983 | 6310402 |
| the glucocorticoid receptor binds to defined nucleotide sequences near the promoter of mouse mammary tumour virus. | glucocorticoids are known to induce the transcription of integrated proviral mouse mammary tumour virus (mmtv) genes in a variety of cell lines derived from mouse mammary tumours. chimaeric genes in which selectable markers are linked to the long terminal repeat (ltr) region of mmtv can be induced by the synthetic glucocorticoid dexamethasone after introduction into mouse fibroblasts. this suggests that the regulatory elements required for hormonal induction are located within the cloned ltr fra ... | 1983 | 6310405 |