| induction of gd3 ganglioside by adenovirus e1a gene 13s- and 12s-mrna products in rat 3y1 cells. | the effect of the expression of the human adenovirus type 12 e1a gene on ganglioside composition of rat 3y1 cells was investigated using cell lines established by introduction of recombinant vector dna containing the e1a 13s- or 12s-mrna cdna placed downstream of the hormone-inducible promoter of mouse mammary tumor virus. ganglioside gd3 was newly detected after switching on of either 13s- or 12s-mrna cdna by addition of dexamethasone. a kinetic study indicated that gd3 was expressed 8 h after ... | 1990 | 2144522 |
| induction of a variety of tumors by c-erbb2 and clonal nature of lymphomas even with the mutated gene (val659----glu659). | the c-erbb2 gene is expressed uniquely in fetal epithelium in vivo and has been suggested to contribute to the development and/or progression of adenocarcinomas in man. in order to assess the oncogenicity of the c-erbb2 gene in vivo, normal c-erbb2 and mutant c-erbb2 encoding glutamic acid instead of valine at position 659 within the transmembrane domain were introduced into mice under the transcriptional regulatory unit of mouse mammary tumor virus long terminal repeat (mmtv-ltr) or immunoglobu ... | 1990 | 2153076 |
| proviral insertions within the int-2 gene can generate multiple anomalous transcripts but leave the protein-coding domain intact. | we examined the effects of mouse mammary tumor virus integration on the multiple rna transcripts expressed from the int-2 proto-oncogene in virally induced breast tumors. proviral insertion either upstream or downstream of the gene could simultaneously activate transcription from three dissimilar int-2 promoters. in some tumors, the activating provirus lies within the transcription unit and disrupts the structures of the various rnas. insertions in the 5' region of the gene had complex effects d ... | 1990 | 2153243 |
| in vitro and in vivo growth and casein gene expression of mouse mammary tumor epithelial cells in response to hormones. | cells from autochthonous mouse mammary carcinomas which display estrogen-independent growth in vivo were studied for their hormonal responses in primary culture. a culture system employing insulin-supplemented, serum-free medium and basement membrane matrigel as a substratum was used to cultivate tumor cells. the cells did not exhibit in vitro estrogen- or prolactin-dependent growth. primary tumors still displayed a constitutional expression of alpha-, beta-, and gamma-casein mrnas. these messag ... | 1990 | 2153557 |
| hormonal induction of transfected genes depends on dna topology. | plasmids containing the hormone regulatory element of mouse mammary tumor virus linked to the thymidine kinase promoter of herpes simplex virus and the reporter gene chloramphenicol acetyltransferase of escherichia coli respond to glucocorticoids and progestins when transfected into appropriate cells. in the human mammary tumor cell line t47d, the response to progestins, but not to glucocorticoids, is highly dependent on the topology of the transfected dna. although negatively supercoiled plasmi ... | 1990 | 2153920 |
| growth factors induce phosphorylation of the na+/h+ antiporter, glycoprotein of 110 kd. | the na+/h+ antiporter, which regulates intracellular ph in virtually all cells, is one of the best examples of a mitogen- and oncogene-activated membrane target whose activity rapidly changes on stimulation. the activating mechanism is unknown. a na+/h+ antiporter complementary dna fragment was expressed in escherichia coli as a beta-galactosidase fusion protein, and a specific antibody to the fusion protein was prepared. use of this antibody revealed that the na+/h+ antiporter is a 110-kilodalt ... | 1990 | 2154036 |
| demonstration of a new mouse mammary tumor virus locus in the genome of the mammary tumor prone strain shn mouse. | until this report, there have been no detailed analyses of the mouse mammary tumor virus (mmtv) loci in the mammary tumor prone strain shn. using a probe, which hybridizes to the env sequence of mmtv, southern blotting of genomic dna from the brain after digestion with ecori revealed 5 endogenous proviruses: mtv-1 (4.5kb), mtv-2 (11 kb), mtv-8 (6.7kb), mtv-17 (8.3kb) and a newly-found 6.5-kb fragment. f1-hybrid mice (c3h/he female x shn male) also possessed the 6.5-kb fragment. thus, we conclude ... | 1990 | 2154203 |
| [molecular mechanisms of mmtv-induced tumor development]. | | 1990 | 2155437 |
| nucleosome positioning modulates accessibility of regulatory proteins to the mouse mammary tumor virus promoter. | minichromosomes containing the mmtv hormone responsive element (hre) exhibit precisely positioned nucleosomes. chromatin reconstitution of short hre dna fragments also results in precise positioning of nucleosomes as revealed by footprinting, which suggests that information for nucleosome phasing is contained within this short sequence. while hormone receptors bind naked dna and reconstituted nucleosomes with similar affinities (3- to 5-fold difference), nfi, a transcription factor essential for ... | 1990 | 2155706 |
| progesterone receptor stimulates transcription of mouse mammary tumour virus in a cell-free system. | in higher eukaryotes, steroid receptors are general modulators of gene activity which bind to dna hormone response elements (hres) in the vicinity of regulated promoters. analysis of mutant and chimaeric receptor proteins in gene transfer experiments has identified the domains responsible for hormone binding, interaction with the hres and transactivation, but the transactivating function of hormone receptors has proved difficult to reproduce in cell-free assays. here we describe a crude in vitro ... | 1990 | 2156171 |
| dna rearrangements of the int region in spontaneous mouse mammary tumors of shn/s and sln/s mice. | shn and sln mice originating from the same swiss albino stock are genetically very close to each other. the incidence and latent period of mammary tumor development in shn mice were higher and shorter than those in sln. to elucidate these differences in the behavior of mammary tumorigenesis, the frequency of insertion of mammary tumor viral genes within the int-1 and int-2 regions in spontaneous mammary tumors from their two substrains, shn/s and sln/s, were compared. the frequency of provirus i ... | 1990 | 2156546 |
| harderian gland pathology in transgenic mice carrying the mmtv/v-ha-ras gene. | twenty-four harderian glands from 16 transgenic mice carrying a v-ha-ras gene under the control of the mouse mammary tumor virus promoter were examined histologically upon death of the animals. eight glands were histologically normal and eleven were hyperplastic. four additional glands showed predominantly hyperplasia, but also contained foci of dysplasia and in situ carcinoma. one gland contained an adenocarcinoma. the range of pathology observed in the harderian glands of these transgenic mice ... | 1990 | 2156784 |
| insertion mutation of the int-1 and int-2 loci by mouse mammary tumor virus in premalignant and malignant neoplasms from the gr mouse strain. | mouse mammary tumor virus (mmtv)-induced mammary adenocarcinomas can develop from several different premalignant precursors common in gr mice. insertion mutagenesis of the mammary protooncogenes int-1 and int-2 was studied in this multistep system by analyzing samples from various stages of neoplastic development for novel int-1 and int-2 restriction fragments generated by mmtv provirus integration. int-1 and int-2 insertion mutations were observed in both premalignant lesions and malignant tumo ... | 1990 | 2157060 |
| transforming growth factor-beta represses transcription of the mouse mammary tumour virus dna in cultured mouse mammary cells. | increased expression of mouse mammary tumour virus (mmtv) is associated with hyperplastic alveolar growth and subsequent development of mammary cancers in the mouse. the expression of this virus is repressed when mammary tumour cells undergo sarcomatous transformation. we have demonstrated that a spontaneous progression of mouse mammary adenocarcinoma cells into highly malignant cells with the transformed phenotype is accompanied by an increased expression of transforming growth factors alpha an ... | 1990 | 2157176 |
| suppression of mouse mammary tumor proviral dna and protooncogene expression: association with nutritional regulation of mammary tumor development. | chronic energy intake restriction (ceir) reduces mouse mammary tumor virus (mmtv)-induced mammary tumors in c3h/ou mice. fewer than 10% of c3h/ou mice developed mammary tumors during 88 wk of study when subjected to ceir regardless of calorie source (fat vs. carbohydrate). by contrast, 100% of mice fed ad libitum diets relatively high in fat or carbohydrate or a commercial diet developed tumors by 35-40 wk. mmtv proviral dna transcription was shown to be activated in spleen, liver, lung, kidney, ... | 1990 | 2157199 |
| molecular events in b lymphocyte differentiation. inducible expression of the endogenous mouse mammary tumor proviral gene, mtv-9. | we have previously shown that the steady state levels of transcripts encoded by an endogenous mouse mammary tumor virus (mmtv) increase during lps-induced differentiation of both normal b lymphocytes and an inducible b cell lymphoma, ch12. a large body of evidence suggests that mmtv expression is primarily limited to mammary tissues and that expression in cell lines from nonmammary tissues is accompanied by viral amplification and alterations in the transcriptional control regions of the viral l ... | 1990 | 2157765 |
| high level expression of wild type and variant mouse glucocorticoid receptors in chinese hamster ovary cells. | we have isolated chinese hamster ovary (cho) cell lines expressing elevated levels of wild-type (w) and mutant forms of the glucocorticoid receptor (gr) using the technique of coamplification with a selectable dihydrofolate reductase (dhfr) cdna. a prominent doublet at 90/92 kilodaltons was observed by western blotting or labeling with [3h]-dexamethasone mesylate in extracts from cells transfected with w, the hormone binding mutant (na), and the dna binding mutant (nb). quantification of recepto ... | 1990 | 2157974 |
| the proto-oncogene int-1 encodes a secreted protein associated with the extracellular matrix. | the proto-oncogene int-1 plays an important role in mammary tumorigenesis when activated by proviral insertions of the mouse mammary tumor virus. in normal mouse tissues the gene is expressed in the embryonic neural tube, suggesting a developmental function, while in drosophila the homolog of int-1 is the segment polarity gene wingless. in order to study the protein products of int-1 we have derived fibroblast cell lines infected with multiple copies of a retroviral vector expressing int-1 cdna. ... | 1990 | 2158444 |
| transcription initiated by rna polymerase ii and purified transcription factors from liver. a complex set of promoter sequences governs formation of the initial complex. | using a transcription system derived from rat liver, we have investigated the function of the tata-box and cap site/initiator regions in assembly of stable intermediates on the pathway leading to formation of a functional rna polymerase ii preinitiation complex. our findings argue that neither the tata-box region nor the cap site/initiator region functions independently in the binding of transcription factors during formation of these intermediates, but, rather, the two sequence elements functio ... | 1990 | 2159003 |
| transcriptional regulation of the interleukin 2 gene by glucocorticoid hormones. role of steroid receptor and antigen-responsive 5'-flanking sequences. | dexamethasone treatment of the jurkat t77 cell clone inhibited the enhancing effect of 12-o-tetradecanoylporbol-13-acetate (tpa) and the calcium ionophore a23187 on the interleukin 2 (il2) mrna levels and gene transcription from intact nuclei. dexamethasone treatment of jurkat t77 cells inhibited the tpa/a23187-dependent activation of the transcription from the transfected pil2cat, containing 600 base pairs of the genomic sequences upstream of the coding region of il2 gene, including the tpa/cal ... | 1990 | 2159467 |
| extra mouse mammary tumor proviruses in dba/2 mouse lymphomas acquire a selective advantage in lymphocytes by alteration in the u3 region of the long terminal repeat. | we determined the nucleotide sequences of the long terminal repeats (ltrs) from mouse mammary tumor virus (mmtv) proviruses acquired in two dba/2 mouse lymphoma cell lines, mla and dl-8. proviruses from mla contained a 352-base-pair deletion from nucleotides 669 to 1020 in the u3 region of the ltr, whereas the ltr alteration of the dl-8 provirus involved both a similar 360-base-pair deletion and generation of a tandem repeat region consisting of sequences of flanking deletions. to assess the fun ... | 1990 | 2159524 |
| the long terminal repeat region of the mouse mammary tumour virus contains multiple regulatory elements. | mouse mammary tumour virus (mmtv) is the major aetiologic agent of mouse mammary tumour formation. the expression of this virus is regulated by steroid hormones and cell type specific factors. the nucleotide sequence that controls the steroid hormone response has already been localized between -202 and -59 upstream of the start of transcription in the long terminal repeat (ltr) region of the proviral dna. through transfection experiments in three different cultured mouse cell lines (nih3t3, nmum ... | 1990 | 2159634 |
| glucocorticoid receptor-dependent disruption of a specific nucleosome on the mouse mammary tumor virus promoter is prevented by sodium butyrate. | our laboratory has previously developed cell lines derived from mouse nih 3t3 fibroblasts and c127 mammary tumor cells that stably express mouse mammary tumor virus (mmtv) long terminal repeat fusion genes in bovine papillomavirus-based episomes. glucocorticoid hormone strongly activates transcription from episomes and induces the disruption of a single nucleosome in an array of phased nucleosomes on the mmtv promoter. sodium butyrate inhibits the glucocorticoid hormone-dependent development of ... | 1990 | 2160080 |
| a congenic line of the balb/c mouse strain with the endogenous mouse mammary tumor virus proviral gene mtv-3: tissue-specific expression and correlation with resistance to mouse mammary tumor virus infection and tumorigenesis. | mouse mammary tumor virus (mmtv) expression and mmtv-induced tumorigenesis were studied in a congenic line of the balb/chea strain, termed balb/c-mtv-3+, that carries the mtv-3 proviral gene. balb/c-mtv-3+ mice were free of milk-transmitted mmtv and did not spontaneously develop mammary tumors. a specific mtv-3 expression was observed in the mammary gland and spleen, but not in other lymphoid tissues, such as thymus and bone marrow. this expression was hormone dependent, as shown by the increase ... | 1990 | 2160325 |
| developmental and hormonal regulation of a mouse mammary tumour virus glycoprotein in normal mouse mammary epithelium. | a radioimmunoassay was developed and validated for the major glycoprotein (gp58) of the mouse mammary tumour virus (mmtv). using this assay, the expression of gp58 during pregnancy and lactation was found to parallel that for mmtv rna. in particular, there was a very rapid induction in late pregnancy and a decline in late lactation, although some residual expression persisted well into involution. in cultures of normal mouse mammary tissue, induction of gp58 occurred after a 24-h lag period and ... | 1990 | 2160825 |
| avian endogenous provirus (ev-3) env gene sequencing: implication for pathogenic retrovirus origination. | the avian endogenous env gene product blocks the surface receptor and, as a result, cells become immune to related exogenous retroviruses. on the other hand, the same sequence can be included in the pathogenic retrovirus genome, as shown by oligonucleotide mapping. however, since the complete env gene sequence was not known, the comparison of genomic nucleotide sequences was not possible. therefore an avian endogenous provirus with an intact env gene was cloned from a chicken gene bank and the r ... | 1990 | 2161159 |
| molecular cloning and primary structure analysis of the mouse mammary tumor virus-related element from dwarf hamster genome. | | 1990 | 2161160 |
| construction and hormone regulation of a novel retroviral vector. | we report the analysis of a self-inactivating retroviral vector, constructed to allow inducible gene expression of inserted sequences from the mouse mammary tumour virus hormonal response element. the cloning strategy has been designed to allow for ease of insertion of the genes of interest. the vector contains the aph gene, allowing geneticin-resistance selection in mammalian cells. we have characterised dexamethasone (dex)-induced increase in gene expression using the reporter gene encoding ch ... | 1990 | 2161384 |
| [sequences homologous to mouse mammary cancer virus are common in mammalian and avian genomes]. | sequences distantly related to mouse mammary tumor virus (mrs) were found in a wide range of mammalian genomes using blot hybridization. the number of mrs copies and the degree of their relationship with the hybridization probe varied and did not correlate with the evolutionary similarity of the species. nevertheless, within a genus the set of mrs was species-specific and reflected the degree of relationship between species. mrs were also found in avian genomes and the degree of their relationsh ... | 1990 | 2161490 |
| development of mammary hyperplasia and neoplasia in mmtv-tgf alpha transgenic mice. | to study the role of transforming growth factor alpha (tgf alpha) in normal mammary development and mammary neoplasia in vivo, we have generated transgenic mice in which a human tgf alpha cdna is expressed under the control of the mmtv enhancer/promoter. overexpression of tgf alpha in the mammary epithelium, as confirmed by in situ hybridization and immunohistochemistry, is associated with hyperplasia of alveoli and terminal ducts in virgin female and pregnant transgenic mice. a range of morphol ... | 1990 | 2161707 |
| wnt-3, a gene activated by proviral insertion in mouse mammary tumors, is homologous to int-1/wnt-1 and is normally expressed in mouse embryos and adult brain. | we have isolated a common insertion site, wnt-3, for proviruses of the mouse mammary tumor virus (mmtv). of mammary tumors induced by the gr variant of mmtv, 5% contains a provirus at wnt-3, which is located on mouse chromosome 11. the gene is transcribed into a 3.8-kilobase (kb) mrna in tumors with nearby proviral insertions but not in tumors with proviruses at other loci or in most adult tissues. normal expression of wnt-3 is detected in mouse embryos (with a peak around day 12 of gestation) a ... | 1990 | 2162045 |
| glucocorticoids regulate expression of the v-mycok10 oncogene in a murine retroviral vector with chimeric momulv-mmtv ltrs. | a murine retrovirus which expresses the v-mycok10 oncogene under the control of the dexamethasone-regulatable mouse mammary tumor virus (mmtv) promoter has been constructed. in this vector, denoted pmimyc, the moloney murine leukemia virus (momulv) sequences required for virus replication, integration and packaging were kept, while all the elements for transcription regulation were derived from the mmtv long terminal repeat (ltr). after transfection of nih 3t3 fibroblasts with this construct, a ... | 1990 | 2162166 |
| nuclear factor i acts as a transcription factor on the mmtv promoter but competes with steroid hormone receptors for dna binding. | several steroid hormones induce transcription of the mouse mammary tumor virus (mmtv) promoter, through an interaction of their respective receptors with the hormone responsive elements (hres) in the long terminal repeat (ltr) region. the molecular mechanism underlying transcriptional activation is not known, but binding of nuclear factor i (nfi) to a site adjacent to the hre appears to be required for efficient transcription of the mmtv promoter. in jeg-3 choriocarcinoma cells the mmtv promoter ... | 1990 | 2162764 |
| [retroviruses and breast cancer]. | | 1990 | 2163571 |
| ucla colloquium. new insights into breast cancer: the molecular biochemical and cellular biology of breast cancer. | | 1990 | 2163750 |
| tumor idiotype vaccines. vii. analysis and correlation of structural, idiotypic, and biologic properties of protective and nonprotective ab2. | we have previously generated and used anti-id mab (ab2) to induce protective immunity against the l1210 dba/2 tumor and for immunotherapy of established tumors. among various anti-id that were typed serologically as internal image ab2 of the mouse mammary tumor virus tumor-associated ag gp52, only one induced protective immunity and was effective in immunotherapy. in this study we compared the structural, idiotypic, and network properties of the protective and nonprotective antiidiotypic antibod ... | 1990 | 2164069 |
| cloning of minute virus of mice cdnas and preliminary analysis of individual viral proteins expressed in murine cells. | cdnas corresponding to rna from the autonomous parvovirus minute virus of mice were cloned into constitutive and inducible expression vectors. these clones generate viral ns2, vp1, and vp2 proteins individually. initial examination of these clones by transient expression analysis and analysis of stably transformed murine cell lines inducibly expressing these constructs indicated that they will be useful tools for characterizing the function of individual minute virus of mice gene products. | 1990 | 2164605 |
| activation of retrovirus in transgenic mice: association with development of olfactory neuroblastoma. | a line of transgenic mice that express the human adenovirus type 12 e1a and e1b genes under the regulatory control of the mouse mammary tumor virus long terminal repeat was studied. mice from this line develop olfactory neuroblastomas at approximately 6 months of age. large numbers of type c retrovirus (ecotropic murine leukemia virus) particles were found in the tumor rosettes. no similar examples of virus activation were identified in tumors from other transgenic experiments. examination of sp ... | 1990 | 2164606 |
| lipopolysaccharide and dexamethasone induce mouse mammary tumor proviral gene expression and differentiation in b lymphocytes through distinct regulatory pathways. | endogenous mouse mammary tumor virus (mmtv) proviral transcripts are up regulated during the normal course of b-lymphocyte differentiation. we report here that the regulatory mechanisms which lead to increased levels of mmtv transcripts in differentiating, lipopolysaccharide (lps)-stimulated normal b cells and in the inducible b-cell lymphoma line ch12 are at least partially distinct from those controlling increases in immunoglobulin and j-chain gene expression. in studies designed to characteri ... | 1990 | 2164635 |
| the int genes in mouse mammary tumorigenesis and in normal development. | in mice, the mouse mammary tumour virus causes tumours by insertional activation of host cell oncogenes. by the application of transposon tagging techniques, several cellular oncogenes, called int, have been discovered. the int-1 gene encodes a cysteine-rich protein with a signal peptide, suggesting that it may act as an extracellular growth or differentiation factor. normally, the int-1 gene is expressed in early embryogenesis of the mouse, in particular in the developing nervous system. the es ... | 1990 | 2164908 |
| wild type human p53 is antiproliferative in sv40-transformed hamster cells. | the transformation related protein p53 has been implicated in the process of normal cell proliferation and neoplastic transformation. in this study, the influence of wild type human p53 on cell proliferation was examined. plasmid constructs encoding the wild type human p53 and various mutant p53 cdnas, driven by the mouse mammary tumor virus (mmtv) promoter linked to the dominant biochemical selection marker gpt, were used in a colony forming assay employing sv40 transformed hr8 hamster cells. p ... | 1990 | 2165234 |
| the nxsm recombinant inbred strains of mice: genetic profile for 58 loci including the mtv proviral loci. | we report the construction of 17 recombinant inbred (ri) strains of mice derived from the progenitor strains nzb/binre and sm/j and the typing of this ri strain set, designated nxsm, for 58 loci distributed on 16 autosomes and the x chromosome. two backcrosses involving nzb/binj and sm/j were constructed to confirm chromosomal assignments and determine gene orders suggested from nxsm ri strain data. from these results we recommend that chromosomal assignments and gene orders suggested from analy ... | 1990 | 2165966 |
| functional elements of the steroid hormone-responsive promoter of mouse mammary tumor virus. | transcription from the promoter of mouse mammary tumor virus is subject to induction by several classes of steroid hormones as well as to repression by a negative regulatory element present in the long terminal repeats of proviral dna. in order to characterize the functional elements of the promoter that in some way must respond to these regulatory signals, a number of promoter mutations were constructed, including a set of linker-scanning mutations across the entire promoter region. analysis of ... | 1990 | 2166825 |
| segregation patterns of endogenous mouse mammary tumor viruses in five recombinant inbred strain sets. | we identified mouse mammary tumor proviral loci in the akr/j, c3h/hej, c57bl/6j, c57l/j, dba/2j, and swr/j inbred mouse strains and determined their segregation patterns in the akxd, akxl, bxd, bxh, and swxl recombinant inbred strain sets. two new mtv loci, mtv-29 and mtv-30, were identified. mtv-30 was genetically mapped to chromosome 12. additionally, two previously identified mtv loci, mtv-14 and mtv-23, were genetically mapped to chromosome 4 and chromosome 6, respectively. | 1990 | 2166832 |
| mouse mammary tumor virus (mmtv) infection in swiss and riii mice. correlation between resistance to exogenous infection and anti-mmtv serum response. | host-virus relationships were examined in mice from the two mouse mammary tumor virus (mmtv)-infected strains swiss mb+ and riii, which harbour the same mmtv variant, and from the derived sublines swiss mb- and riiif, which were freed of milk-borne mmtv by foster-nursing. these two strains are not phylogenetically related, the swiss strain bearing the endogenous mtv-3 locus in its dna. in riii and swiss mb+ mice, the incidence of early mammary tumors, which was of 96% and 8%, respectively, was c ... | 1990 | 2167058 |
| transcription stimulates homologous recombination in mammalian cells. | transcription stimulates homologous recombination in saccharomyces cerevisiae and has been implicated in the control of recombinational events during the development of mammalian immune systems. here, we describe a plasmid-based system in which an inducible promoter from the mouse mammary tumor virus is located upstream of heteroallelic neomycin genes carried on two plasmids. pairs of plasmids are introduced into chinese hamster ovary cells by electroporation, and recombination is monitored by s ... | 1990 | 2167441 |
| the dose dependence of glucocorticoid-inducible gene expression results from changes in the number of transcriptionally active templates. | glucocorticoid hormones induce the transcription of genes having glucocorticoid response elements in a dose dependent manner. to determine whether this dose dependence represents a response of individual templates or of the mass of templates, we introduced a bacterial beta-galactosidase gene linked to the glucocorticoid-inducible enhancer/promoter of the mouse mammary tumor virus (mtv) into ltk- cells and obtained stable transformants containing a single or a few templates per cell. visual inspe ... | 1990 | 2167833 |
| distribution of mouse mammary tumor virus-related sequences does not correlate with the taxonomic position of their hosts. | sequences (mrs) distantly related to mouse mammary tumor virus (mmtv) were found in genomes of a wide range of mammalian species using blot hybridization. the number of mrs copies and the degree of their homology with the hybridization probe varied and did not correlate with the taxonomic position of the species. nevertheless, within a genus the set of mrs was species specific and reflected the taxonomic relation between the species. mrs were also found in avian genomes and the degree of their h ... | 1990 | 2168108 |
| influence of mammary cell differentiation on the expression of proteins encoded by endogenous balb/c mouse mammary tumor virus genes. | the interactions between differentiation-associated cellular events in the intact mammary gland or in cultured mammary cells and the post-transcriptional activity of the endogenous mouse mammary tumor virus (mmtv) loci were investigated. the transcriptional activities of the endogenous mmtv proviruses of the balb/c mouse strain (mtv-6, mtv-8 and mtv-9) appear to be regulated differentially during pregnancy-induced mammary gland development (j.e. knepper, d. medina and j.s. butel, j. virol. 59, 5 ... | 1990 | 2168113 |
| role of chromatin structure in transcriptional regulation of mmtv ltr hormone-dependent promoter. | studies of chromatin structure were performed in mouse fibroblast cell lines containing bovine papilloma virus (bpv) based artificial minichromosomes containing mouse mammary tumor virus (mmtv) long terminal repeat (ltr), a retroviral promoter regulated by glucocorticoids, driving the transcription of v-ha-ras. these minichromosomes fractionate with the "active chromatin", indicating an association of the minichromosomes with components of the "nuclear matrix". two regions of the minichromosomes ... | 1990 | 2168572 |
| cyclic amp and calcium in mouse mammary tumour virus expression: effects and post-transcriptional site of action. | the role of cyclic amp (camp), calcium, calmodulin and protein kinase c (pkc) in the expression of both mouse mammary tumour virus (mmtv) rna and an mmtv glycoprotein, gp58, was investigated in normal mammary epithelium in culture. none of these second messengers had any effect on mmtv rna. dibutyryl camp alone had no effect on gp58 levels but, at low concentrations (0.05-0.1 mm), it nearly doubled the induction seen with insulin, cortisol and prolactin; higher concentrations were inhibitory. al ... | 1990 | 2168707 |
| affinity of interactions between human glucocorticoid receptors and dna: at physiologic ionic strength, stable binding occurs only with dnas containing partially symmetric glucocorticoid response elements. | sucrose density gradient shift assays were adapted to permit determination of the affinity of interaction between human glucocorticoid receptors (gr) and dna under conditions of dna excess. saturation analyses were performed to ascertain dissociation constants for the interaction of activated human gr with each of five dna fragments. centrifugation of gr-dna complexes on sucrose gradients under nearly isotonic salt conditions revealed similar affinities with dissociation constants in the range o ... | 1990 | 2168738 |
| establishment of ddd/1-mtv-2/mtv-2, nu/nu and ddd/1-mtv-2/mtv-2, nu/+ mice: preliminary characterization in relation to mtv antigen expression and mammary tumorigenesis. | to investigate the effects of the t-cell deprivation on viral mammary tumorigenesis, two double congenic mouse strains of the ddd genetic background, ddd/1-mtv-2/mtv-2, nu/nu and ddd/1-mtv-2/mtv-2, nu/+, were produced by the cross between ddd/1-mtv-2/mtv-2 (ddd-mtv-2) and ddd/1-nu/nu mice, followed by repeated intercross breedings. expression of the mouse mammary tumor virus (mtv)-gp52 antigen was demonstrated in the mammary glands of mice from 14 days on, in both -nu/nu and -nu/+ females. mamma ... | 1990 | 2168807 |
| thyroid hormone requirement for retinoic acid induction of mouse mammary tumor virus expression. | in normal mouse mammary epithelium, insulin, cortisol, and prolactin are absolute requirements for mouse mammary tumor virus expression. retinoic acid further increased mouse mammary tumor virus expression two- to threefold but only when triiodothyronine was also present; neither retinoic acid nor triiodothyronine alone had any effect. | 1990 | 2168995 |
| contacts between steroid hormone receptors and thymines in dna: an interference method. | understanding the mechanisms by which regulatory proteins recognize genetic information stored in dna relies on the availability of methods to analyze their interaction with individual nucleotides and their reactive groups. here we describe the use of kmno4 to analyze the contacts between steroid hormone receptors and thymines within a hormone responsive element. although several pyrimidine residues are highly conserved among different receptor binding sites their participation in sequence recog ... | 1990 | 2169621 |
| mechanism and biological significance of the ha-ras-induced activation of the na+/h(+)-antiporter. | expression of the transforming ha-ras oncogene in mmtv-ltr transfected nih 3t3 cells leads to a growth factor independent activation of the na+/h(+)-antiporter. the activation of the antiporter is insensitive to the protein kinase inhibitor staurosporine and equally expressed in protein kinase c-depleted cells. it is concluded that the ha-ras induced activation of the antiporter occurs by a protein kinase c-independent mechanism. an inhibition of the na+/h(+)-antiporter by dimethylamiloride or a ... | 1990 | 2169700 |
| constitutive expression of the c-fos protooncogene in murine keratinocytes: potentiation of the mitogenic response to insulin-like growth factor 1. | in order to determine the biological effects of activation of the c-fos protooncogene on growth and differentiation of balb/mk mouse keratinocytes, these cells were transfected with the plasmid pman-fos, which encompasses the human c-fos coding region under transcriptional control of a mouse mammary tumor virus promoter, as well as the gene encoding neomycin phosphotransferase. of approximately 70 individual clones obtained by selection in geneticin, 5 clones that constitutively expressed c-fos ... | 1990 | 2170007 |
| recombinant human glucocorticoid receptor induces transcription of hormone response genes in vitro. | a recombinant full length human glucocorticoid receptor stimulates transcription in vitro of test genes containing synthetic glucocorticoid and progesterone response elements or murine mammary tumor virus promoter. the receptor expressed in a baculoviral vector is highly active, enhancing transcription of hormone response genes greater than 30-fold even at a receptor concentration of 1.2 nm. the enhancement of transcription is glucocorticoid and progesterone response element-dependent, suggestin ... | 1990 | 2170364 |
| quantitative analysis of the glucocorticoid receptor-dna interaction at the mouse mammary tumor virus glucocorticoid response element. | purified glucocorticoid receptor (gr) from rat liver was used for a quantitative analysis of the protein-dna interaction at specific gr-binding segments within the 5'-long terminal repeat of the mouse mammary tumor virus. a truncated receptor was generated and used to demonstrate formation of heterodimeric gr, which furthermore was shown to be in rapid equilibrium with receptor-monomer. the relative affinity for gr binding to specific gr sites versus random calf thymus dna was approximately 2 x ... | 1990 | 2170368 |
| oestrogen enhances the responsiveness of the mmtv-ltr to glucocorticoid in zr-75-1 human breast cancer cells. | treatment of zr-75-1 human breast cancer cells with oestrogen has no direct effect on the expression of a transfected mmtv-ltr but enhances its inducibility in response to glucocorticoid treatment. this effect which can be produced with both oestradiol and diethylstilbestrol is specific to induction of the mmtv-ltr, no effect of the treatment on expression driven by the rsv-ltr being observed. the effect can be observed in cells pre-treated with oestrogen prior to removal of dna and glucocortico ... | 1990 | 2170763 |
| virus envelope-based peptide vaccines against virus-induced mammary tumors. | previous studies by us and others established that mammary tumors induced by murine mammary tumor virus (mumtv) could be prevented to various extents by prior vaccination with mumtv-containing or subviral component immunogens. in this report, four predicted surface-accessible peptide regions (ep-1 to ep-4) of the major viral envelope glycoprotein (gp52) of c3h-mumtv were tested as carrier-conjugated vaccines for the protection of balb/c mice against a live virus challenge. with tumor incidence a ... | 1990 | 2171218 |
| the interaction of a c-jun/fos related protein factor with the u3 sequences of the mouse mammary tumor virus ltr. | using polyacrylamide gel mobility shift assay we have detected a nuclear factor (nf-s) in a mouse mammary tumor cell line (gr) that binds to an upstream sequence domain (-766 to -737) near the 5'-end of the mouse mammary tumor virus (mmtv) long terminal repeat (ltr). antibodies to the products of the jun and fos oncogenes interfered with the binding potential of this factor, indicating that the factor shares antigenic determinants with c-jun/ap-1. in vitro translated c-jun and c-fos were also fo ... | 1990 | 2171522 |
| binding of the glucocorticoid receptor induces a topological change in plasmids containing the hormone-responsive element of mouse mammary tumor virus. | glucocorticoid hormones stimulate transcription of the mouse mammary tumor virus (mmtv) promoter by means of an interaction of the hormone receptor with a set of upstream dna-binding sites called the hormone-responsive element (hre). in an attempt to understand the underlying molecular mechanism, we have analyzed the influence of receptor binding on the topological state of plasmids carrying different parts of the hre. incubation of negatively supercoiled plasmids containing the intact hre with ... | 1990 | 2171552 |
| the processed pseudogene of mouse thymidine kinase is active after transfection. | aside of the gene coding for cytoplasmic thymidine kinase, the genome of mouse cells carries two pseudogenes. both are inactive in situ. one of the pseudogenes is a processed pseudogene in which a two base pair deletion caused a shift of the reading frame and a shortening of the gene product from the 233 amino acids of thymidine kinase to 177 amino acids in the pseudogene product. we report here that introduction of this pseudogene into ltk- cells gave rise to cells with a thymidine kinase posit ... | 1990 | 2171983 |
| effects of energy restriction on mouse mammary tumor virus mrna levels in mammary glands and uterus and on uterine endometrial hyperplasia and pituitary histology in c3h/shn f1 mice. | we investigated the effects of energy restriction on the pituitary-ovarian axis and on a hormone responsive gene, the mouse mammary tumor virus (mmtv). female c3h/shn f1-hybrid mice, known to display a high incidence of mammary tumors, ate an energy-restricted diet (48 kcal/wk) or a control diet (95 kcal/wk) beginning at the time of weaning. by 67 wk of age, 12 of 32 mice in the control group, but none of the 33 mice in the energy-restricted group, had developed mammary tumors. six tumor-free mi ... | 1990 | 2172493 |
| prolactin and glucocorticoid hormones control transcription of the beta-casein gene by kinetically distinct mechanisms. | transcription of the beta-casein milk protein gene in the hc11 mouse mammary epithelial cell line is induced synergistically by the hormones glucocorticoid and prl. sequential treatment of hc11 cells with glucocorticoid and prl demonstrated that the two hormones had different modes of action on beta-casein transcription. pretreatment with dexamethasone enhanced the response to subsequent induction by prl, but not vice versa. dexamethasone increased the sensitivity of the cells to respond to prl. ... | 1990 | 2172795 |
| expression of recombinant androgen receptor in cultured mammalian cells. | full-length rat and human androgen receptor (ar) cdna clones were expressed in cos-7 and cv1 monkey kidney cells to analyze the ar protein using immunological and cotransfection techniques. the studies were aided by the development of two rabbit polyclonal antibodies, designated ar32 and ar52, directed against epitopes within the n-terminal region of ar. each antibody recognizes native ar by sucrose gradient analysis and detects a 114-kilodalton protein in cos cells transfected with human or rat ... | 1990 | 2172802 |
| genetic diversity of spontaneously developed primary and metastatic mammary tumor cells in mice. | metastatic cells are often considered to be clonal derivatives of one of the primary tumor cell subpopulations. to determine if the cells of spontaneously developed lung nodules in a mammary tumor-bearing mouse represent the major or minor population of the cells in the primary tumor, comparisons were made of the pattern of their mouse mammary tumor virus (mmtv) proviral integrations, and their insertional mutations of the mouse mammary tumor proto-oncogenes, int-1 and int-2. of the 78 tumor-bea ... | 1990 | 2173623 |
| [comparison of background factors relevant to mammary tumorigenesis between ddd/1-mtv-2/mtv-2 congenic and ddd/1 mice]. | to elucidate the possible participation of the mtv-2 gene in the background factors relevant to mammary tumorigenesis, ddd/1-miv-2/mtv-2 (ddd-mtv-2) congenic and ddd/1 background mice were compared for endocrine and immune organs, mammary gland development, expression of mouse mammary tumor virus (mmtv)-gp 52 antigen, hyperplastic alveolar nodules (han) and mammary tumor incidence. the congenic strain had been established by introducing mtv-2 from grs/ajms (gr) into ddd/1 mice by repeated 12 bac ... | 1990 | 2173665 |
| naf, a trans-regulating negative-acting factor encoded within the mouse mammary tumor virus open reading frame region. | the mouse mammary tumor virus (mmtv) long terminal repeat (ltr) open reading frame (orf) encodes a negative acting factor (naf). in our test system, naf mediates its effect in trans on another mmtv provirus in which the 5' ltr has been replaced by that of rous sarcoma virus. naf effects are evidenced at the level of transcriptional initiation rather than as reduced mrna stability. the introduction of a premature termination codon into the mmtv ltr-encoded orf abolishes the transcriptional down r ... | 1990 | 2173798 |
| breast cancer sequences identified by mouse mammary tumor virus (mmtv) antiserum are unrelated to mmtv. | | 1990 | 2174415 |
| high expression of ras p21 correlates with increased rate of abnormal mitosis in nih3t3 cells. | the modulation of responsive genes by hormonal stimulation is an attractive in vitro model system for the study of a wide variety of biological processes. using this methodology we have investigated the effect of the human oncogene protein p21ras on mitosis using mouse mammary tumor virus long terminal repeat (mmtv-ltr)-directed gene expression. following the induction of p21 protein, abnormal mitotic figures were scored in metaphase and anaphase. elevated expression of p21 was associated with m ... | 1990 | 2174524 |
| tumorigenesis and male sterility in transgenic mice expressing a mmtv/n-ras oncogene. | transgenic mice carrying the activated n-ras oncogene under the transcriptional control of the mouse mammary tumor virus (mmtv) long terminal repeat were produced. the transgene is expressed in a tissue distribution consistent with the fact that it is driven by the mmtv-ltr, and similarly to mmtv/h-ras constructs, its presence elicits tumors in harderian, mammary and salivary glands. in addition it appears to compromise male reproductive function, which has not been described with the other ras ... | 1990 | 2174525 |
| role of the int-genes in murine mammary tumor development and implications for human breast cancer. | | 1990 | 2175298 |
| dna rotational positioning in a regulatory nucleosome is determined by base sequence. an algorithm to model the preferred superhelix. | mmtv-ltr sequences -190/-45 position a histone octamer both in vivo and in vitro. experimental evidence suggested that nucleosome rotational positioning is determined by the dna sequence itself. we developed an algorithm that is able to predict the most favorable path of a given dna sequence over a histone octamer, based on rotational preferences of different dinucleotides. our analysis shows that these preferences are sufficient for explaining the observed rotational positioning of the mmtv-ltr ... | 1990 | 2175885 |
| tissue-specific factors and glucocorticoid receptors present in nuclear extracts bind next to each other in the promoter region of mouse mammary tumor virus. | nuclear extracts from different mouse tissues have been used to study the interaction of factors with the steroid-inducible promoter of mouse mammary tumor virus. in addition to the glucocorticoid receptor that interacts with the distal region of the promoter, several tissue-specific proteins were found to bind to the 5' flanking region of the receptor-binding site and to the basal promoter region. the differences in the pattern of protection observed suggest that tissue-specific factors might c ... | 1990 | 2176241 |
| structural features of a regulatory nucleosome. | dna sequences from the long terminal repeat of the mouse mammary tumor virus (mmtv-ltr) position nucleosomes both in vivo and in vitro. here, were present chromatin reconstitution experiments showing that mmtv-ltr sequences from -236 to +204 accommodate two histone octamers in positions compatible with the in vivo data. this positioning is not influenced by the length of the dna fragment and occurs in linear as well as in closed circular dna molecules. mmtv-ltr dna sequences show an intrinsic be ... | 1990 | 2176242 |
| characterization of oligosaccharide chains on mouse mammary tumor virus envelope proteins and the implications for the mechanism of their glucocorticoid regulated processing. | glucocorticoid hormone is required for complete posttranslational processing of the glycosylated mouse mammary tumor virus envelope precursor, pr74env in the murine t-lymphosarcoma cell line, w7mg1. metabolic labeling studies with [35s]methionine, [3h]galactose, and [3h]mannose, combined with enzymatic digestion analyses with a variety of endoglycosidases, demonstrated that both proteolytic processing and n-linked oligosaccharide maturation depended, either directly or indirectly, on glucocortic ... | 1990 | 2177143 |
| potentiation of oncogenic n-ras-induced neurite outgrowth and ornithine decarboxylase activity by phorbol dibutyrate and protein kinase inhibitor h-8. | a recombinant n-ras oncogene, under the transcriptional control of a corticosteroid-inducible mouse mammary tumor virus (mmtv) promoter, has been stably transfected into a pc12 rat pheochromocytoma subline. this cell line, designated ur61, undergoes n-ras-induced neurite outgrowth and cessation of division when treated with dexamethasone (guerrero et al.: biochemical and biophysical research communications 150:1185-1192, 1988). we have employed the ur61 cell line as a model for ras oncogene-indu ... | 1990 | 2180965 |
| stable expression of mouse cyp1a1 and human cyp1a2 cdnas transfected into mouse hepatoma cells lacking detectable p450 enzyme activity. | using the mouse hepatoma hepa-1c1c7 c37 mutant cell line that exhibits negligible benzo[a]pyrene hydroxylase (cyp1a1) and acetanilide 4-hydroxylase (cyp1a2) enzyme activities, we developed stable transfectants of plasmids containing the murine cyp1a1 (cytochrome p(1)450) and the human cyp1a2 (p(3)450) cdnas. we show that the assay measuring metabolism of ethoxyfluorescein ethyl ester (efee) was invaluable in screening large numbers of individual cell lines for high cyp1a1 enzyme activity. nine d ... | 1990 | 2206399 |
| functional characterizations of the androgen receptor confirm that the molecular basis of androgen action is transcriptional regulation. | in an effort to understand the molecular basis of androgen action in the prostate, we isolated androgen receptor (ar) cdna from rat ventral prostate cells and analyzed the transcriptional regulatory activity of the encoded protein in a cotransfection assay. we found that ar is capable of inducing chloramphenicol acetyltransferase activity more than 20-fold using the mouse mammary tumor virus ltr as a source of androgen response elements. this induction was observed in both monkey cv1 cells and h ... | 1990 | 2274054 |
| definition of the human androgen receptor gene structure permits the identification of mutations that cause androgen resistance: premature termination of the receptor protein at amino acid residue 588 causes complete androgen resistance. | we have isolated and characterized the gene encoding the human androgen receptor. the coding sequence is divided into eight coding exons and spans a minimum of 54 kilobases. the positions of the exon boundaries are highly conserved when compared to the location of the exon boundaries of the chicken progesterone and human estrogen receptor genes. definition of the intron/exon boundaries has permitted the synthesis of specific oligonucleotides for use in the amplification of segments of the androg ... | 1990 | 2293020 |
| calorie consumption level influences development of c3h/ou breast adenocarcinoma with indifference to calorie source. | to analyze simultaneously the influence attributable to calorie consumption level and percentage of dietary fat on the spontaneous development of mammary adenocarcinoma, virgin female c3h/ou mice were separated into five dietary groups. four groups of mice were fed purified diets either ad libitum (16-18 kcal/mouse/day) or restricted 40% in calorie consumption (10-11 kcal/mouse/day), and diets contained either 4.5%, 7.5%, 67%, or 68% calories from fat. mice that consumed isocaloric diets develop ... | 1990 | 2294519 |
| differentiation-dependent expression of provirus-activated int-1 oncogene in clonal cell lines derived from a mouse mammary tumor. | the int-1 mammary oncogene is frequently activated by proviral insertion in mouse mammary tumors. to characterize the target cell for the oncogenic action of int-1, we have isolated permanent cell lines with distinct morphologies and differentiation characteristics, starting from a tumor with a rearranged int-1 gene. polygonal cells had retained many differentiation markers of epithelial cells and produced adenocarcinomas upon transplantation in syngenic mice. sphere-forming-cuboidal cells are p ... | 1990 | 2326076 |
| two distinct estrogen-regulated promoters generate transcripts encoding the two functionally different human progesterone receptor forms a and b. | the human progesterone receptor (hpr) cdna, synthesized from t47d breast cancer cells, and the hpr gene 5'-flanking region were cloned and sequenced. comparison of the cdna-deduced amino acid sequence with other pr homologues demonstrated the modular structure characteristic of nuclear receptors. as in the case of the chicken homologue, there are two hpr forms, a and b, which originate from translational initiation at aug2 (codon 165) and aug1, respectively. northern blot analysis of t47d mrna u ... | 1990 | 2328727 |
| glucocorticoid-dependent maturation of mouse mammary tumor virus glycoproteins in mouse lymphoma cells: isolation of variants with constitutive viral protein maturation and normal glucocorticoid receptor function. | the posttranslational maturation and cell surface localization of mouse mammary tumor virus (mmtv) envelope glycoproteins is regulated by glucocorticoid hormone in mouse t-lymphoma cell line w7mg1. only when the cells are cultured with glucocorticoid is the mmtv envelope precursor, pr74, converted efficiently to the two mature proteolytic products, gp52 and gp33. by immunological selection we have isolated protein-processing variants that express the mature viral proteins constitutively on the c ... | 1990 | 2330009 |
| a single base mutation in the androgen receptor gene causes androgen insensitivity in the testicular feminized rat. | the complete form of androgen insensitivity is an inherited x-linked syndrome in which genetic males fail to undergo masculinization in utero due to defective functioning of the androgen receptor (ar). the molecular basis of androgen insensitivity was investigated in the testicular feminized (tfm) rat with this syndrome. ar mrna size and amount, as well as nuclear ar protein revealed by immunocytochemistry, suggested normal expression of the ar gene in the tfm rat. sequence analysis of the ar co ... | 1990 | 2341409 |
| specific region in hormone binding domain is essential for hormone binding and trans-activation by human androgen receptor. | complementary dna (cdna) clones encoding human-androgen receptors (har) were isolated using synthetic oligonucleotides homologous to the human glucocorticoid, estradiol, progesterone, and aldosterone receptors as probes to screen a human testis lambda gt11 cdna library. one of the receptor proteins (hara) produced in vitro bound the [3h]dehydrotestosterone ([3h]dht) with high affinity and selectivity similar to the human androgen receptor present in target tissues and cells. a second cdna clone ... | 1990 | 2342476 |
| isolation of a genomic sublibrary enriched for glucocorticoid-regulated genes. | glucocorticoids regulate gene expression by causing the glucocorticoid receptor to bind to an enhancer-like dna element termed the glucocorticoid regulatory element (gre). the resultant effect on transcription of specific genes causes a cascade of intracellular events that determines the growth or differentiated function of the target tissue. although virtually all animal tissues respond to glucocorticoids, it has proven difficult to elucidate the molecular events which underlie physiologically ... | 1990 | 2344394 |
| biosynthesis of peptide precursors and protease inhibitors using new constitutive and inducible eukaryotic expression vectors. | a series of expression vectors has been constructed as based on the pml derivative of pbr322. the eukaryotic transcription units employ various promoters followed by polycloning sites for 3-9 commonly used restriction enzymes and are completed by the sv40 polyadenylation sequence. in 4 of the vectors, designed for co-transfection or transient expression studies, only a single transcription unit containing either a constitutive or an inducible promoter was incorporated. the human ubiquitin (ubc) ... | 1990 | 2379587 |
| cooperativity and specificity in the interactions between dna and the glucocorticoid receptor dna-binding domain. | we have employed fluorescence spectroscopy to study the chemical equilibrium between a 115 amino acid protein fragment containing the dna-binding domain of the human glucocorticoid receptor (dbdr) and a 24-base-pair dna oligomer containing the glucocorticoid response element (gre) from the mouse mammary tumor virus promoter region and compared it with the binding to nonspecific dna at various ionic conditions. we find that binding to both dnas is cooperative but that dbdr shows a higher affinity ... | 1990 | 2383551 |
| a new class of endogenous human retroviral genomes. | human dna contains multiple copies of a novel class of endogenous retroviral genomes. analysis of a human recombinant dna clone (hlm-2) containing one such proviral genome revealed that it is a mosaic of retroviral-related sequences with the organization and length of known endogenous retroviral genomes. the hlm-2 long terminal repeat hybridized with the long terminal repeat of the squirrel monkey virus, a type d retrovirus. the hlm-2 gag and pol genes share extensive nucleotide sequence homolog ... | 1985 | 2408338 |
| dysdifferentiative nature of aging: age-dependent expression of mouse mammary tumor virus and casein genes in brain and liver tissues of the c57bl/6j mouse strain. | many aspects of the aging process could be the result of cells slowly drifting away from their proper state of differentiation. this possibility has been studied by searching for an age-dependent increase in the expression of specific genes in tissues where expression of these genes would not normally be expected. in these studies, cdna probes of specific genes are used in a dna x na hybridization assay to detect possible complementary rna sequences in tissues of different-aged animals. using th ... | 1985 | 2408592 |
| [expression of antigens related to structural protein antigens of mmtv in breast cancer cells]. | this study was concerned with expression of mmtv-related antigens in cells of stable mcf-7 and t47d lines of human breast cancer. indirect immunoperoxidase technique using antisera against whole preparations of virus of riii and c3h mice as well as certain mmtv proteins identified cells which express proteins cross-reactive with both gp52 and p27. mcf-7 sublines with a high level of positive cells were obtained. the stimulating effect of pregnancy and lactation hormones on mmtv-related proteins ... | 1985 | 2411055 |
| genetic relatedness between intracisternal a particles and other major oncovirus genera. | intracisternal a particles represent a major oncovirus genus. by reciprocal hybridization between molecularly cloned a particles and representatives of other oncovirus genera, we established pol gene homology with type b, type d and avian type c viruses. the most extensive homology was with mammalian type d viruses. the transcriptional orientation of the iap genome was determined, as well as evidence indicating that its pol gene, which is apparently defective, contains coding regions for both re ... | 1985 | 2411061 |
| molecular basis of altered mouse mammary tumor virus expression in the d-2 hyperplastic alveolar nodule line of balb/c mice. | the preneoplastic d-2 hyperplastic outgrowth line, which was derived from a hormone-induced hyperplastic alveolar nodule (han) of a balb/c mouse, was used for a detailed analysis of mouse mammary tumor virus (mmtv) expression. the d-2 han line has previously been shown to express viral rna representative of the entire genome, although viral particles have been noted only rarely. the mmtv-specific mrna, protein, and dna content of the d-2 tissues was defined in an effort to better understand the ... | 1985 | 2414907 |
| att20 pituitary tumour cells contain mouse mammary tumour virus and intracisternal a-type particles in addition to murine leukemia virus. | by electron microscopy and immunocytochemistry we have examined the retroviruses endogenous to att20 d16v cells, a cloned line of murine pituitary tumour cells. in addition to the c-type retrovirus particles related to rauscher murine leukemia virus (mulv) previously reported to bud from these cells we observed cytoplasmic a-type particles and intracisternal a-type particles (iap). in the cytoplasm the a-type particles occur in large clusters often associated with sheets of material with a fine ... | 1985 | 2417843 |
| murine mammary tumor virus pol-related sequences in human dna: characterization and sequence comparison with the complete murine mammary tumor virus pol gene. | sequences in the human genome with homology to the murine mammary tumor virus (mmtv) pol gene were isolated from a human phage library. ten clones with extensive pol homology were shown to define five separate loci. these loci share common sequences immediately adjacent to the pol-like segments and, in addition, contain a related repeat element which bounds this region. this organization is suggestive of a proviral structure. we estimate that the human genome contains 30 to 40 copies of these po ... | 1986 | 2418214 |
| mammary tumorigenesis and tumor morphology in four c3h sublines with or without exogenous mammary tumor virus. | mammary tumorigenesis was surveyed in retired breeding females in four sublines of the c3h strain: in standard milk-transmitted early oncogenic mouse mammary tumor virus (mmtv)-infected c3h/he and c3h/ki mice, and in standard milk-transmitted early oncogenic mmtv free c3hf/he and c3hf/ki mice. all of 58 c3h/ki mice and 98% (306 of 309) of the c3h/he mice developed palpable mammary tumors at average ages of 276 and 284 days, respectively. thirty-one % (47 of 152) of the c3hf/ki mice and 77% (168 ... | 1986 | 2418961 |
| effects of 5-azacytidine on expression of endogenous retrovirus-related sequences in c3h 10t1/2 cells. | in a previous study (22) we found that transient exposure of c3h 10t1/2 mouse embryo fibroblasts to 5-azacytidine (5-azac) induced several changes in growth properties. the treated cells showed progressive changes in morphology, saturation density, growth rate, and serum dependence. by passage 5, the cells had acquired the ability to grow in 0.3% agarose, and by passage 30, they had given rise to fully transformed foci that grew in agarose, agar, and liquid suspension. this progression was rapid ... | 1986 | 2419582 |