| interferon induced inhibition of enveloped viruses. | | 1985 | 2421308 |
| ultrastructural characterization of the retrovirus particles (sm-mtv) liberated from the mammary tumor cell line (sm-mt) of a house musk shrew, suncus murinus (insectivora). | detailed ultrastructure of a new type of retrovirus (sm-mtv) released by cultured cells (sm-mt) of a spontaneous mammary tumor from a house musk shrew suncus murinus, insectivora, is described. the virus particles were revealed as three forms: intracellular; budding; and extracellular. the intracellular type a particles were similar in profile to those associated with mouse mammary tumor cells and tended to form a small cluster of several particles in the cytoplasm. in addition, horseshoe-shaped ... | 1986 | 2421890 |
| steroid regulation of transfected genes in mouse mammary tumour cells. | the regulation of mouse mammary tumour virus (mmtv) rna by glucocorticoid hormones is well-established and has provided much information on how steroid hormones work. however, we have shown that androgens can also control mmtv rna accumulation in s115 mouse mammary tumour cells. this novel androgen action could be explained on the basis that the mmtv long terminal repeat (ltr) can respond to several classes of steroid if appropriate receptors are present in the cells. we have used transfection e ... | 1986 | 2422444 |
| histological distribution of mtv antigen in mice detected by immuno-peroxidase staining. | histological localization of mammary tumor virus (mtv) antigen was investigated using a variety of organs high (dd/tbr, shn, sln, gr) and low (balb/c) mammary cancer mice strains and immuno-peroxidase staining with mtv antigen. except for balb/c strain mice, the mammary gland and mammary tumors were generally positive. accessory male genital organs including the prostate, seminal vesicle, and coagulating gland also demonstrated a positive reaction, but the testis and female genital organs includ ... | 1986 | 2425548 |
| reciprocal interference between milk-transmitted mammary tumor virus and friend leukemia viruses in mice: possible role of the interferon system. | we have previously shown that mice simultaneously infected with the murine mammary tumor virus (mumtv) and with certain slow murine leukemia viruses (mlv) have an increased resistance to the pathological effects of both agents. here we report that milk-transmitted mumtv also delays the development of the acute erythroleukemia induced by friend leukemia virus (flv), and retards, or prevents in some cases, the development of long-term lymphomas caused by its helper component. this is confirmed by ... | 1986 | 2425940 |
| regulation of cellular phenotype and expression of polyomavirus middle t antigen in rat fibroblasts. | polyoma middle t antigen (mt) was expressed in rat f-111 cells under control of the dexamethasone-regulatable mouse mammary tumor virus promoter. graded phenotypic responses to levels of mt induction by the hormone were seen, with morphological transformation, focus formation, and anchorage-independent growth requiring increasing levels of mt expression. the ability of different clones to form tumors reflected their maximum level of induction of mt-associated kinase and their ability to grow in ... | 1985 | 2426583 |
| circularization of retroviral genomic rna and the control of rna translation, packaging and reverse transcription. | translation, packaging and reverse transcription of the genomic rna of retroviruses appear to be regulated by short and long range rna-rna interactions which take place within the 5'-600 nt and between the 5' and 3' untranslated sequences. the 5' (r and u5) and 3' (dr and u3) domains of the genomic rna together with the nucleic acid binding protein (nbp) would control the balance between the open state of the viral genomic rna, correlated with an efficient rna translation and the closed state, w ... | 1986 | 2427127 |
| glucocorticoid agonists as well as antagonists are effective inducers of mouse mammary tumor virus rna in mouse mammary tumor cells treated with inhibitors of adp-ribosylation. | glucocorticoids increase expression of specific genes by a mechanism involving binding to and "activation" of a specific receptor protein. other steroids, such as ru 486, bind to the glucocorticoid receptor but the resultant steroid-receptor complex is unable to activate glucocorticoid sensitive genes. in the present study we have observed that steroid regulation of the glucocorticoid-regulated mouse mammary tumor virus (mmtv) genome in cultured mouse mammary tumor cells is altered by treatment ... | 1986 | 2428821 |
| two proto-oncogenes implicated in mammary carcinogenesis, int-1 and int-2, are independently regulated during mouse development. | the int-1 and int-2 genes were first isolated as targets for transcriptional activation by proviral insertion mutations in mammary carcinomas induced by the mouse mammary tumor virus (mmtv). since these proto-oncogenes are not expressed at detectable levels in previously tested normal tissues from adult mice, we sought to determine whether these genes might be active during embryogenesis by examining mouse embryos and cultured teratocarcinoma cells for rna encoded by int-1 and int-2. a single si ... | 1986 | 2429320 |
| sequence relationships of type d retroviruses which cause simian acquired immunodeficiency syndrome. | simian acquired immunodeficiency syndrome (saids) in macaque monkeys is caused by type d retroviruses; three independent virus isolates are identified as srv-1 (saids retrovirus-serotype 1), srv-2, and mpmv (mason-pfizer monkey virus). virions from these three isolates have serologically related core antigens, but distinct surface proteins. also, srv-2 is unique since it apparently induces retroperitoneal fibromatosis in addition to saids. the complete dna sequence of molecularly cloned srv-2 is ... | 1987 | 2435057 |
| silver enhancement of protein a-gold probes on resin-embedded ultrathin sections. an electron microscopic localization of mouse mammary tumor virus (mmtv) antigens. | a simple method is described allowing the enhancement of the visibility of small gold probes for the electron microscopy. this method, which allows the silver intensification of gold directly on epon-embedded ultrathin sections, was used for the electron microscopic localization of mouse mammary tumor virus (mmtv) antigens in cultured cells derived from gr and balb/cfriii mouse mammary tumors. after the immunostaining with the preembedding protein a-gold technique, the ultrathin sections, placed ... | 1987 | 2437083 |
| tenascin is a stromal marker for epithelial malignancy in the mammary gland. | tenascin is an extracellular matrix glycoprotein that is not present in the normal mature rat mammary gland. the distribution of tenascin was examined by immunohistochemistry in mammary tumors from carcinogen-treated and untreated rats, in virus-induced mammary tumors from mice, and in a variety of mammary gland lesions from humans. tenascin was detectable in the stroma of the malignant but not of the benign tumors from all species. an inhibition elisa, testing homogenates of rat tumors, confirm ... | 1987 | 2440026 |
| ultrastructural and immunological studies of virus particles observed in a t-cell line derived from a mouse spontaneous lymphoma. | intracytoplasmic type a virus particles in clusters, associated with budding, immature type b and mature type b-like particles were observed in a t-cell line derived from a spontaneous lymphoma of an a/j mouse. these particles shared the antigenic determinants with murine mammary tumor virus from riii, c3h, and gr strains as revealed by both indirect immunofluorescence and immunoperoxidase methods at ultrastructural level. | 1987 | 2440229 |
| tumor-specific idiotype vaccines. iii. induction of t helper cells by anti-idiotype and tumor cells. | in a previous report, we have demonstrated the induction of tumor-specific immunity by monoclonal anti-idiotype antibodies generated against a monoclonal anti-tumor antibody, 11c1, that also cross-reacts with mouse mammary tumor virus envelope glycoprotein gp52. also, we showed that whereas one anti-idiotype antibody, 2f10, could induce protective immunity, another anti-idiotype antibody, 3a4, induced nonprotective immunity. here we demonstrated the existence of t helper cells which recognize an ... | 1987 | 2442262 |
| assessment of preferential cleavage of an actively transcribed retroviral hybrid gene in murine cells by deoxyribonuclease i, bleomycin, neocarzinostatin, or ionizing radiation. | preferential cleavage induced by bleomycin, neocarzinostatin, or ionizing radiation in a transcribed cellular gene was evaluated through comparisons with deoxyribonuclease i. the glucocorticoid-inducible ltl gene (a hybrid viral gene derived from mouse mammary tumor virus dna) previously described [zaret, k. s., & yamamoto, k. r. (1984) cell (cambridge, mass.) 38, 29-38] served as the specific dna target. a southern blot analysis was used to specifically assess cleavage of the ltl gene in nuclei ... | 1987 | 2445373 |
| characterization of ribosomal frameshifting in hiv-1 gag-pol expression. | based on precedents from other retroviruses, the precursor of the human immunodeficiency virus (hiv-1) reverse transcriptase is predicted to be a polyprotein with a relative molecular mass (mr) of 160,000 (160k) encoded by both the viral pol gene and the upstream gag gene. these two genes lie in different translational reading frames, with the 3' end of gag overlapping the 5' end of pol by 205 or 241 nucleotides. thus, production of the gag-pol fusion protein would require either messenger rna p ... | 1988 | 2447506 |
| glucocorticoid receptor binding to defined regions of alpha 2u-globulin genes. | a dna-cellulose competition assay was used to study binding of glucocorticoid receptor complexes to two alpha 2u-globulin genes, rap 01 and rao 01. two binding regions were found in rap 01, one localized between bp -642 and -452, the other between -252 and -118 from the transcriptional initiation site. only the second region was found in rao 01. the binding affinity was comparable to that observed using a long terminal repeat fragment of mouse mammary tumor virus. both regions contain sequences ... | 1987 | 2447887 |
| optimized reaction conditions and specific inhibitors for initiation of transcription by rna polymerase ii in nuclei from cultured mammalian cells. | an assay that employs guanosine 5'-o-(2-thiotriphosphate) was used to measure correct initiation of rna chains in isolated cell nuclei, where chromatin structure is relatively undisturbed. rna chains initiated with guanosine 5'-o-(2-thiotriphosphate) were separated from the remaining rna by mercury-sepharose column chromatography and analyzed for correctly initiated mouse mammary tumor virus rna with a t1 nuclease protection assay. the monovalent cation concentration dependence for initiation in ... | 1988 | 2449443 |
| isolation and characterization of interferon-resistant variants from s49 mouse lymphoma. | s49 mouse lymphoma cells were found to be extremely sensitive to the antiproliferative activity of interferon. these characteristics were studied to select for ifn-resistant cell variants. some 0.6% of the parental s49 cell population were resistant to the antiproliferative and cytotoxic activities of ifn. the resistant cells were cloned and analyzed for their responses to several of the activities of ifn, namely, inhibition of encephalomyocarditis (emc) virus, murine leukemia virus (mulv) repli ... | 1988 | 2455652 |
| morphologic and antigenic properties of mouse mammary tumor virus produced in a hormone-responsive fashion by c57bl/10 mammary tumors of non-viral origin. | bl-matu/a1 mouse mammary tumor cells, derived from a c57b1/10 mammary adenocarcinoma induced by dimethylbenzanthracene and mammotropic hormones, express virus particles and proteins related to mouse mammary tumor virus (mmtv). immunocytochemical analysis by means of monospecific and monoclonal anti-gp52 sera revealed a different localization of the main structural proteins of mmtv in bl-matu/a1 and gr cells (the latter used as a positive virus-producing control). immunoelectron microscopy of b-t ... | 1988 | 2456634 |
| detection in the blood serum of breast cancer patients of circulating immune complexes containing antigens showing common epitopes with structural proteins of mouse mammary tumour virus (mmtv). | in the blood serum of a proportion of breast cancer patients (29.4%) immune complexes specifically reacting with the immunoglobulins of the serum against mmtv structural proteins were detected using indirect enzyme-linked immunosorbent assay (elisa). the presence of such complexes could decrease the titre of antibodies reactive with mmtv in the blood serum of breast cancer patients. | 1988 | 2456679 |
| the hbv x-orf encodes a transactivator: a potential factor in viral hepatocarcinogenesis. | we report here on a transactivating function of hbv dna. the effect is shown by stimulation of transient expression of psv2cat dna in cotransfected human liver ccl13 cells. transfection experiments with plasmid constructs containing different hbv dna fragments and northern analyses of rna from cells transfected with these recombinant plasmids indicate that a transactivating function is encoded within the x-orf. a frameshift mutation within the x gene causes loss of activity thus demonstrating re ... | 1988 | 2457861 |
| transactivating potential of the 3' open reading frame of murine mammary tumor virus. | the procaryotic chloramphenicol acetyltransferase (cat) gene controlled by the murine mammary tumor virus (mmtv) promoter shows reduced activity in a rat mammary tumor cell line after infection with mmtv but to a considerably lesser extent than the cat gene controlled by a heterologous promoter, indicating trans-acting regulation of promoter activity by mmtv. cotransfection of vectors capable of expressing rna from the 3' open reading frame (orf) of mmtv with the cat-mmtv construct resulted in e ... | 1988 | 2459415 |
| polyomavirus transforms rat f111 and mouse nih 3t3 cells by different mechanisms. | polyomavirus middle tumor antigen (mt) was expressed in a line of mouse nih 3t3 cells under control of the dexamethasone-regulatable mouse mammary tumor virus promotor. contrary to rat f111 cells which were rendered anchorage independent by mt expression alone (l. raptis, h. lamfrom, and t.l. benjamin, mol. cell. biol. 5:2476-2487, 1985), mt-producing nih 3t3 cells were unable to grow in agar even after full mt induction. the mt:pp60c-src-associated phosphatidylinositol kinase was activated in t ... | 1989 | 2463382 |
| posttranscriptional regulation of cellular gene expression by the c-myc oncogene. | the c-myc oncogene has been implicated in the development of many different cancers, yet the mechanism by which the c-myc protein alters cellular growth control has proven elusive. we used a cdna hybridization difference assay to isolate two genes, mr1 and mr2, that were constitutively expressed (i.e., deregulated) in rodent fibroblast cell lines immortalized by transfection of a viral promoter-linked c-myc gene. both cdnas were serum inducible in quiescent g0 fibroblasts, suggesting that they a ... | 1989 | 2467185 |
| anti-alpha-galactosyl antibodies in chagasic patients. possible biological significance. | 1. antibodies from chagasic patients (ch), bound to a column of immobilized purified glycoprotein 25-kda antigen of trypanosoma cruzi epimastigotes (gp25), were partially lytic (70% lysis at 50 micrograms/ml) to cultured metacyclic trypomastigotes (y strain) in a complement-mediated reaction (alternative pathway). 2. antibodies (ch) eluted with galactose from a melibiose-agarose column reacted in elisa titration plates with gp25, whole cells of metacyclic trypomastigotes (y strain), and less int ... | 1988 | 2471563 |
| binding of androgen-receptor complexes to alpha 2u-globulin genes and to the long terminal repeat of mouse mammary tumor virus. | the binding of androgen-receptor complexes to fragments derived from two alpha 2u-globulin genes (rap 01 and rao 01) was studied using a dna-cellulose competition assay. rat prostate cytosol labelled with [3h]mibolerone was used as a source of the androgen receptor. two controls were included in these studies: the long terminal repeat (ltr) of mouse mammary tumor virus which has previously been shown to act as an androgen response element and a fragment of the c3 gene of prostatic binding protei ... | 1989 | 2477291 |
| effect of simulated american, bulgarian, and japanese human diets and of selenium supplementation on the incidence of virally induced mammary tumors in female mice. | in attempts to simulate the effects of diet on human breast cancer development groups of female c3h mice infected with mammary tumor virus (mmtv-) were maintained on diets formulated to resemble the typical american, bulgarian, and japanese human diets. the incidence of mammary tumors was the highest (84%) in group of mice receiving the simulated meat- and fat-rich american diet, which was also low in selenium (se content: 0.15 ppm). the appearance of mammary tumors was delayed in the mice maint ... | 1989 | 2484397 |
| a highly inducible system of gene expression by positive feedback production of glucocorticoid receptors. | to investigate the function of a cloned gene, inducible enhancer/promoters are preferred for controlling the level of expression experimentally. highly inducible gene expression systems with both low basal levels and enhanced maximal levels of expression are especially sought. we have developed a new expression system using a positive feedback mechanism. glucocorticoid receptor cdna was fused to the enhancer/promoter of mouse mammary tumor virus (mtv) to induce receptor production. simultaneous ... | 1989 | 2494026 |
| the purified activated glucocorticoid receptor is a homodimer. | the structure of purified preparations of activated (dna-binding) glucocorticoid receptor (gr) was analyzed in the presence or absence of dna. a 35-base pair dna fragment harboring a strong gr-binding site from the mouse mammary tumor virus promoter (-189/-166) was used for stoichiometric analysis of the gr.dna complex. glycerol gradient centrifugation was utilized in order to separate the 6 s gr.dna complex from the 4 s gr and the 3 s dna fragment. synthetic glucocorticoid [3h]triamcinolone ace ... | 1989 | 2494184 |
| characterization of a presecretory phase in b-cell differentiation. | we have identified and characterized an inducible in vitro subclone of the ch12 b-cell lymphoma, ch12-lbk, which appears to represent a transitional phase in the b-cell differentiation pathway. this phase, which we call the "presecretory" phase, falls between replicating b cells that are not secreting antibodies and b cells that secrete antibody at a high rate. presecretory cells are characterized by abundant steady-state levels of immunoglobulin and joining (j) chain transcripts and of protein ... | 1989 | 2495536 |
| int-1--a proto-oncogene involved in cell signalling. | the int-1 gene was originally identified as a locus activated by mouse mammary tumor virus insertion. cloning and sequencing of the mouse gene indicates that int-1 encodes a 41k, 370 amino acid, cysteine-rich protein with a potential hydrophobic signal peptide sequence. expression studies clearly indicate that int-1 enters the secretory pathway and is probably secreted, although definitive evidence is lacking. drosophila int-1 encodes the wingless gene, wingless, a segment-polarity gene, is requ ... | 1989 | 2534596 |
| isolation of a pathogenic clone of mouse mammary tumor virus. | exogenous mouse mammary tumor virus (mmtv) was cloned from a gr mammary tumor. clone lambda grt39 contained a full-length integrated mmtv(gr) provirus and both 5' and 3' host flanking dna. the lambda grt39 provirus had no apparent structural changes associated with cloning and retained the exogenous mmtv gag gene poison sequence. when introduced into rat mammary adenocarcinoma la7 cells, the lambda grt39 provirus was fully expressed. lambda grt39-transfected la7 cells made mmtv rna, had gp52 su ... | 1989 | 2535722 |
| amplification of mouse mammary tumor virus genomes in non-mammary tumor cells. | extra proviral copies of mouse mammary tumor virus (mmtv) are known to be present in the genomes of certain t-cell lymphomas of mice. analysis of additional non-mammary tumor cell types known to express mmtv transcripts and antigens revealed the presence of extra acquired mmtv proviruses in a pituitary tumor cell line, a macrophage line, and leydig testicular tumor cells. the nature of the amplified mmtv proviruses in these various tumor cell types differed with regard to copy number and presenc ... | 1989 | 2535749 |
| ultrastructural features of the intestinal absorption of mouse mammary tumor virus in newborn balb/cfriii mice. | the retrovirus mouse mammary tumor virus is present in mouse strains with a high incidence of mammary tumors as a causative agent. it is produced mainly in the mammary glands of sexually mature females and is milk-transmitted to newborns. the fate of the mouse mammary tumor virus is almost unknown. where it enters, how it is distributed, and where it remains latent, remain unresolved problems. this study tries to answer the first of these questions. viruses are for the most part digested in the ... | 1989 | 2535827 |
| expression of human papillomavirus type 16 e7 gene induces dna synthesis of rat 3y1 cells. | human papillomavirus type 16 (hpv 16) open reading frames (orf) e6, e7, and e6e7, placed under the control of dexamethasone-inducible mouse mammary tumor virus long terminal repeat, were introduced into rat 3y1 cells, an immortalized fibroblast line, with the aid of neomycin-selection. the cell clones containing inducible hpv 16 orfs were selected and examined for dna synthesis. following induction of hpv mrna synthesis by the hormone, dna synthesis was stimulated in the cells containing e7 or e ... | 1989 | 2535904 |
| a putative int domain for mouse mammary tumor virus on mouse chromosome 7 is a 5' extension of int-2. | we extended the physical map of the mouse int-2 locus by demonstrating that the site of insertion for mouse mammary tumor virus dna in plaque-type mammary tumors of gr mice is directly linked to int-2. an additional example of proviral integration is described in which a provirus in a presumed enhancer-insertion mode 15 kilobases upstream of the int-2 promoters is capable of activating expression of the gene at levels typical of other virally induced mammary tumors. | 1989 | 2536846 |
| estrogen influence on maturational pathway of murine mammary tumor virus: an immunoelectron microscopy study. | modifications induced by estrogens on hormone-independent murine mammary tumor (mmt) and its main etiological agent, the mmt virus (mmtv), are reported. high doses of estrogens released continuously from silastic capsules delay significantly the development of transplanted tumors into syngeneic hosts. neoplastic cells present a striking cytoplasmic vacuolization and changes in the mmtv differentiation pattern. mature virions are detected budding into cytoplasmic vacuoles instead of the extracell ... | 1989 | 2537750 |
| the role of sex steroids in the expression of mmtv in the normal mouse mammary gland. | infection with the mouse mammary tumor virus (mmtv) is associated with hyperplastic alveolar growth and subsequent tumorigenesis. the role of the sex steroids in the initial phase of this pathological chain of events is investigated in this study. in normal mammary epithelium, progesterone stimulates mmtv rna expression both in vivo (2.6-fold) and in vitro (2.9-fold); although estradiol is ineffective alone, it does enhance the effect of progesterone (6.8- and 5.7-fold stimulation, respectively) ... | 1989 | 2539131 |
| construction and characterization of a packaging cell line for mmtv-based conditional retroviral vectors. | a chimeric provirus in which the 5'ltr of a complete biologically active mouse mammary tumour virus (mmtv) proviral dna has been replaced with the rous sarcoma virus ltr has been constructed. upon transfection into permissive cells, this provirus directs the synthesis of the mmtv gag and env structural proteins, but is impaired in packaging of the rnas that encode these proteins. supertransfection of these cells with mmtv based vector constructs results in the production of infectious recombinan ... | 1989 | 2539144 |
| multihormone regulation of mmtv-ltr in transfected t-47-d human breast cancer cells. | multihormonal regulation on the long terminal repeat (ltr) region of mouse mammary tumour virus (mmtv) has been studied using t-47-d human breast cancer cells stably transfected with the steroid sensitive ltr-c3 chimaeric gene. the specificity of steroid action on transfected ltr sequences has been compared with regulation of endogenous cellular markers. we conclude that the hormone response element of the ltr can be induced by physiological concentrations of androgen, progestin and glucocortico ... | 1989 | 2539537 |
| molecular cloning and sequencing of the mtv-1 ltr: evidence for a ltr sequence alteration. | the vertically transmitted mtv-1 provirus is the primary causative factor of mammary neoplasia in certain c3hf strains that lack the horizontally transmitted mouse mammary tumor virus (mmtv). the studies here report the molecular cloning of the germ line 4.5 kb mtv-1 3' ecori fragment and sequencing of the 3' mtv-1 ltr. the mtv-1 ltr sequence is closely related to the 5' mtv-11 ltr sequence also reported here, as well as to known mtv-8 and mmtv ltr sequences in the portion of mmtv and mtv-8 ltrs ... | 1989 | 2539705 |
| reinfection of virus free mice with mouse mammary tumour virus. | br6/icrf mice carrying a milk-transmitted mammary tumour virus (mmtv) develop tumours after several pregnancies. if the mice are freed from mmtv, no tumours develop. in the experiments described in this paper, mmtv was reintroduced into mmtv-free mice by foster nursing, which was least effective if the pups were exposed to the virus only during the first week of life. exposure for even a short time after that age led to a tumour incidence similar to that found in normally infected mice. reinfect ... | 1989 | 2540382 |
| transgenic mice carrying the mouse mammary tumor virus ras fusion gene: distinct effects in various tissues. | transgenic mice carrying the v-ha-ras oncogene under the control of the mouse mammary tumor virus long terminal repeat were produced. these mice exhibit several phenotypes: mammary tumors, bilateral hyperplasia of the harderian lacrimal gland, primary bronchio-alveolar lung adenocarcinoma, and splenomegaly. high levels of the transgene rna were detected in mammary, harderian, and lung tumors. accumulation of cells of the myeloid lineages was found in enlarged spleens. this phenotype may represen ... | 1989 | 2540427 |
| human progesterone receptor binding to mouse mammary tumor virus deoxyribonucleic acid: dependence on hormone and nonreceptor nuclear factor(s). | using crude progesterone receptor preparations from t47d human breast cancer cells, we show by immunoprecipitation assay that receptor specifically and with high affinity recognizes the hormone response element (hre) of the mouse mammary tumor virus (mmtv). the use of crude preparations minimizes alterations of receptors or loss of associated factors that may occur during purification. specific binding was obtained at 1:1 molar ratios of receptor to dna, and hre sequences are recognized with an ... | 1989 | 2540430 |
| regulation of gene expression by glucocorticoids. | | 1989 | 2540703 |
| expression of active hormone and dna-binding domains of the chicken progesterone receptor in e. coli. | bacterially-expressed fusion proteins containing the dna-(region c) or hormone-binding (region e) domains of the chicken progesterone receptor (cpr) fused to the c terminus of escherichia coli beta-galactosidase were analysed for the specificity of interaction with natural and synthetic hormone-responsive elements (hres) and progestins, respectively. the purified fusion protein containing the progestin-binding domain bound progesterone with an apparent kd of 1.0-1.5 nm and was specifically photo ... | 1989 | 2540961 |
| binding and transepithelial transport of immunoglobulins by intestinal m cells: demonstration using monoclonal iga antibodies against enteric viral proteins. | m cells of intestinal epithelia overlying lymphoid follicles endocytose luminal macromolecules and microorganisms and deliver them to underlying lymphoid tissue. the effect of luminal secretory iga antibodies on adherence and transepithelial transport of antigens and microorganisms by m cells is unknown. we have studied the interaction of monoclonal iga antibodies directed against specific enteric viruses, or the hapten trinitrophenyl (tnp), with m cells. to produce monospecific iga antibodies a ... | 1989 | 2541137 |
| shedding of virus-free mmtv gp52 by nonproducer mammary tumor cells: a source of tumor marker in the presence and absence of dexamethasone. | the envelope glycoprotein of the mouse mammary tumor virus (mmtv gp52), a useful plasma marker for mammary tumors in mice, was measured in extracellular medium by radioimmunoassay to quantitatively compare gp52 levels released by a c3h mmtv producer and its subcloned b9 nonproducer cell line. experiments analyzed levels of viral gp52 released from nonproducer cells both in the presence and absence of dexamethasone (dxs) to compare levels with those of producer cells and to assess quantitative ch ... | 1989 | 2542180 |
| positive and negative modification of dexamethasone-mediated mmtv gp52 release by progesterone pretreatment of tumor cells. | murine mammary tumor cells (c3h mm5mt/cl) were grown in charcoal-stripped serum to examine the effects of hormonal treatments on the expression and release of the mouse mammary tumor virus (mmtv) envelope glycoprotein (gp52). the ability of progesterone to modify extracellular levels of soluble and virion-associated mmtv gp52 was tested singly and as a pretreatment prior to dexamethasone (dxs) stimulation. single treatments with dxs or progesterone demonstrated that dxs was substantially more ef ... | 1989 | 2542181 |
| analysis of gag proteins from mouse mammary tumor virus. | structural proteins designated p10gag, p21gag, p8gag, p3gag, p27gag, and p14gag from the c3h strain of mouse mammary tumor virus (mmtv) were purified by reversed-phase high-pressure liquid chromatography. the n- and c-terminal amino acid sequences and amino acid composition of each protein were determined and compared with the amino acids encoded by the proviral dna sequences for the mmtv gag gene. the results show that each of the purified proteins is a proteolytic cleavage product derived from ... | 1989 | 2542570 |
| absence of mouse mammary tumor virus proviral amplification in chemically induced lymphomas of rf/j mice. | rf/j mice are susceptible to the induction of thymic lymphomas by the carcinogens 3-methylcholanthrene and n-methyl-n-nitrosourea. given the association of mouse mammary tumor virus (mmtv) with certain thymomas, we examined genomic dna from chemically induced lymphomas of rf/j mice for new mmtv proviruses. of 13 tissue culture lines derived from 3-methylcholanthrene-induced tumors, 5 had acquired new proviruses. mmtv amplification coincided with the appearance of viral mrnas and proteins. howeve ... | 1989 | 2542628 |
| glucocorticoids stimulate the release of a viral tumor marker (mmtv gp52) while inhibiting tumor cell growth. | the influence of glucocorticoid treatments on the release of mouse mammary tumor virus (mmtv) envelope antigen (gp52) has been studied in c3h mammary tumor cell cultures and compared to treatment-mediated effects on tumor cell growth. simultaneous assessment of extracellular viral antigen levels and tumor cell growth has indicated that both are coordinately affected by glucocorticoid treatment. while gp52 release is stimulated by treatment, this effect is accompanied by an inhibition of tumor ce ... | 1989 | 2542692 |
| dual function of a nuclear factor i binding site in mmtv transcription regulation. | using linker-scanning mutagenesis we had previously identified four elements within the mmtv ltr which are necessary for transcriptional stimulation by glucocorticoid hormones. two of them overlapped with regions to which the glucocorticoid receptor binds in vitro. the third element contained a nf-i binding site, and the fourth the tata box. here we show that mutations that abolish in vitro binding of nf-i had a negative effect also on the basal activity of the mmtv promoter of ltr-containing pl ... | 1989 | 2542892 |
| characterization of sequences related to the mouse mammary tumor virus that are specific to mcf-7 breast cancer cells. | mouse mammary tumour virus (mumtv) dna hybridized more strongly to two human ecori fragments (6.6 and 9.5 kilobases) in dna from the mcf-7 human breast cancer cell line than in dna from normal human placenta. seven recombinants (nmwv 1e1-7) containing these mumtv-related sequences were identified. hybridization of nmwv 1e probes to southern transfers of human dna suggested that these probes hybridize to multiple sequences in the human genome. the pattern obtained was very similar to that obtaine ... | 1989 | 2544262 |
| glucocorticoid responsiveness of mouse mammary tumor virus (mmtv) promoters in a down-transcription hepatoma tissue culture (htc) variant. | complement-mediated cytolysis of the mouse mammary tumor virus (mmtv)-infected rat hepatoma (htc) cell line, m1.54, resulted in recovery of a mutant derivative, designated cr5, in which the magnitude of both basal and dexamethasone-induced proviral mmtv rna expression was selectively reduced. variant cr5 cells were transfected with a plasmid containing the glucocorticoid-regulated mmtv promoter linked to the neomycin resistance gene (plnl). half-maximal resistance to g418 killing was glucocortic ... | 1989 | 2545481 |
| prolactin regulation of mouse mammary tumor virus (mmtv) expression in normal mouse mammary epithelium. | the hormonal regulation of mouse mammary tumor virus (mmtv) rna in normal mouse mammary epithelium was studied in an explant system. in tissue from parous mice, physiological concentrations of prolactin stimulated mmtv expression, while only pharmacological concentrations of cortisol were effective. regulation in explants from virgin mice was similar to that in parous animals except that the former were less sensitive to prolactin; this relative unresponsiveness may explain why uninduced tissue ... | 1989 | 2545485 |
| cooperative interactions between the grp78 enhancer and promoter elements in hamster fibroblasts. | a non-tissue-specific enhancer derived from the promoter of the rat 78-kda glucose-regulated protein (grp78)-coding gene was tested for its ability to stimulate the activity of its homologous promoter and two heterologous promoters (simian virus 40 and mouse mammary tumor virus). single and double copies of the enhancer were inserted at positions 5' and 3' of the cat-expression vectors under the direction of the above promoters. the recombinant plasmids were transfected into hamster fibroblast k ... | 1989 | 2545535 |
| phorbol ester-inducible t-cell-specific expression of variant mouse mammary tumor virus long terminal repeats. | acquired proviruses of mouse mammary tumor virus (mmtv) in t-cell leukemias of male gr mice have rearrangements in the u3 region of their long terminal repeats (ltr). in contrast to the endogenous nonrearranged mmtv proviruses, these mutated copies are highly expressed in leukemic t cells. to investigate whether the sequence alterations in the ltr are responsible for the high expression of rearranged mmtv proviruses, we made constructs in which normal and variant ltrs drive the bacterial reporte ... | 1989 | 2545916 |
| levels of viral glycoprotein provide a dose-dependent measure of tumor cell inhibition. | a chemosensitivity assay utilizing small replicate mm5mt/c1 c3h mammary tumor cell cultures was developed to determine whether changes in viral antigen expression and release into culture fluids could be utilized as an in vitro measure of chemotherapeutic drug effect. the 52,000 mw viral envelope glycoprotein (gp52) of the mouse mammary tumor virus (mmtv) was measured in culture fluids of control and drug-treated cultures while cell density was simultaneously determined by cell staining and od 6 ... | 1989 | 2545986 |
| highly inducible expression from vectors containing multiple gre's in cho cells overexpressing the glucocorticoid receptor. | a conditional glucocorticoid-responsive expression vector system is described for highly inducible expression of heterologous genes in mammalian cells. this host-vector system requires high level expression of the glucocorticoid receptor (gr) protein in the host cell and multiple copies of the receptor binding site within the expression vector. transfection and selection of chinese hamster ovary cells with expression vectors encoding the rat gr yielded cell lines which express functional recepto ... | 1989 | 2546123 |
| transgenic mouse model for human gastric carcinoma. | to understand the pathogenesis that may be induced by human adenovirus type 12 (ad12), we have generated transgenic mice carrying the ad12 early region 1 under control of the mouse mammary tumor virus long terminal repeat. eleven of 11 male founder mice, but only 2 of 12 females, died between 3 to 4 mo of age. death was associated with presence of tumors at or near the squamocolumnar junction of the stomach. microscopically, these multifocal tumors appeared to arise from hyperplastic epithelium ... | 1989 | 2546160 |
| the mechanism of camp-induced glucocorticoid receptor expression. correlation to cellular glucocorticoid response. | the mechanism of regulation of glucocorticoid receptor (gr) expression by camp was investigated in rat hepatoma cells (htc). incubation of htc cells with the camp-inducing agent, forskolin, caused a significant increase in the levels of both [3h]dexamethasone binding capacity and gr mrna by about 2- to 2.4-fold within 4 h. incubation of htc cells with the camp analogue, 8-bromo-camp, also increased the gr mrna level to a similar degree in a concentration-dependent manner. the increase in gr mrna ... | 1989 | 2547771 |
| use of a glucocorticoid-inducible promoter for expression of herpes simplex virus type 1 glycoprotein gc1, a cytotoxic protein in mammalian cells. | abundant expression of herpes simplex virus type 1 glycoprotein gc (gc1) in transfected mammalian cells has not previously been achieved, possibly because gc1 protein is toxic to cells. to approach this problem, the gc1 coding sequence was placed under the control of the weak but inducible glucocorticoid-responsive promoter from the mouse mammary tumor virus (mmtv) long terminal repeat (ltr). as controls to evaluate for gc1 cytotoxicity, the mmtv ltr promoter was used to express glycoprotein gd1 ... | 1989 | 2548078 |
| the mouse homolog of the hst/k-fgf gene is adjacent to int-2 and is activated by proviral insertion in some virally induced mammary tumors. | the fibroblast growth factor-related protooncogenes, int-2 and hst/k-fgf, are within 17 kilobase pairs of one another on mouse chromosome 7 and are in the same transcriptional orientation. approximately 70% of tumors induced in br6 mice by mouse mammary tumor virus have proviral insertions adjacent to the int-2 gene. we find that the murine homolog of the hst/k-fgf gene can also be transcriptionally activated by the insertion of mouse mammary tumor virus dna either upstream or downstream of the ... | 1989 | 2548184 |
| [the study on in vitro transformation by human papillomavirus type 16 e6/e7 region]. | a nih3t3-derived cell clone (na7) in which human papillomavirus (hpv) 16 early region e6/e7 was inducible by dexamethasone (dxm) under the control of mouse mammary tumor virus long terminal repeat was established. a transforming function for hpv 16 e6/e7 region was analyzed by this established clone. northern blot hybridization demonstrated that the increased expression of pcna/cyclin and c-myc at the confluent state in accordance with the induced expression of e6/e7 region by dxm. although comp ... | 1989 | 2548943 |
| how steroid hormones work. | understanding how steroids work has led to improved comprehension of such derangements of hormonal regulation as testicular feminization. this knowledge has found practical application in the treatment of hormone-dependent cancers. gene therapy, albeit still too primitive to correct steroid-response defects, promises to be a future mainstay of management. | 1989 | 2549083 |
| thermodynamic stability and statistical significance of potential stem-loop structures situated at the frameshift sites of retroviruses. | rna stem-loop structures situated just 3' to the frameshift sites of the retroviral gag-pol or gag-pro and pro-pol regions may make important contributions to frame-shifting in retroviruses. in this study, the thermodynamic stability and statistical significance of such secondary structural features relative to others in the sequence have been assessed using a newly developed method that combines calculations of the lowest free energy of formation of rna secondary structures and the monte carlo ... | 1989 | 2549508 |
| independent glucocorticoid induction and repression of two contiguous responsive genes. | specific dna sequence elements which contain binding sites for the glucocorticoid receptor mediate the action of glucocorticoid hormones on gene transcription. in glucocorticoid-inducible genes, these glucocorticoid-responsive elements behave as hormone-inducible enhancers of transcription. we have taken advantage of the bovine papillomavirus (bpv) system to test the stringency of glucocorticoid regulation of transcription. bpv episomes were constructed to contain two hormone-regulated transcrip ... | 1989 | 2550796 |
| mutations in the hormone regulatory element of mouse mammary tumor virus differentially affect the response to progestins, androgens, and glucocorticoids. | transcription of the mouse mammary tumor virus dna is known to be induced by several steroid hormones. using chimeric mmtv plasmids containing mutations within the hormone regulatory element, we have previously studied the regions required for the glucocorticoid response in mouse fibroblasts. here we report the characterization of elements essential for the stimulation by progestins and androgens as compared with glucocorticoids. the same set of mutant plasmids was transfected into the human mam ... | 1989 | 2550809 |
| a quantitative comparison of dual control of a hormone response element by progestins and glucocorticoids in the same cell line. | progesterone receptor-containing t47d human breast cancer cells are responsive to progestins but fail to respond to other steroid hormones, in particular dexamethasone, because they have no measurable levels of receptors for estrogens, androgens, or glucocorticoids. to quantitatively study dual responsiveness of the mouse mammary tumor virus (mmtv) promoter to progestins and glucocorticoids, we have stably transfected t47d cells with a glucocorticoid receptor (gr) expression vector. a cloned der ... | 1989 | 2550815 |
| unique male mammary tumors developing in the inbred soft-furred field rats millardia meltada. | inbred lines of the soft-furred rat, millardia meltada, were studied with special reference to spontaneous male mammary tumors. adult males had the hyperplastic, pigmented inguinal mammary tissues and frequently developed bilateral mammary tumors. the tumors, no longer pigmented, were histologically well-differentiated adenocarcinomas associated with the myoepithelial cells and showed a variety of growth patterns depending on the stage of progression. they were transplantable to male, but not to ... | 1989 | 2551171 |
| spontaneous progression of hyperplastic outgrowths of the d1 lineage to mammary tumors: expression of mouse mammary tumor virus and cellular proto-oncogenes. | mammary cancer in mice is characterized by progression through defined stages of preneoplasia, with the most common preneoplastic stage being the hyperplastic alveolar nodule (han). we determined the relative levels of rna expression of various cellular proto-oncogenes and endogenous mouse mammary tumor virus genes in outgrowths and tumors of three sublines of the transplantable d1 han preneoplastic outgrowth line. the three sublines differed in relative tumor-producing capabilities. subline d1b ... | 1989 | 2551332 |
| expression of the int-1 and int-2 loci in endogenous mouse mammary tumor virus-induced mammary tumorigenesis in the c3hf mouse. | the int-1 locus appears to be involved in over 80% of c3h exogenous mouse mammary tumor virus (mmtv)-induced mouse mammary tumors, and the int-2 locus appears to be involved in approximately 10% of these tumors. analysis of 46 c3hf mammary tumors resulting from endogenous, rather than exogenous, mmtv infection revealed that only 41% expressed int-1 rna, while 2% expressed int-2 rna. our results suggest that in addition to the int-1 and int-2 loci, other loci may be involved in endogenous-mmtv-in ... | 1989 | 2552179 |
| caloric restriction perturbs the pituitary-ovarian axis and inhibits mouse mammary tumor virus production in a high-spontaneous-mammary-tumor-incidence mouse strain (c3h/shn). | dietary restriction (dr) retards aging and extends maximum life span. it is also known to decrease the incidence of hormone-dependent tumors. in the present investigation, we focussed primarily on the influence of dr on the pituitary-ovarian axis, and subsequently on gene expression of the mouse mammary tumor virus. f1 females from the mating of shn female and c3h male mice were used in this study, since these hybrids display a very high incidence of mouse mammary tumors. the mice weaned at 3 we ... | 1989 | 2552231 |
| host-mediated induction of tumor heterogeneity. | | 1989 | 2552891 |
| no significant correlation between specific antibodies to mouse mammary tumour virus and human cancer. | to study the possible involvement of mouse mammary tumour virus (mmtv) related agent in human cancer we analysed 300 samples of human sera for the presence of antibodies to mmtv structural proteins. all sera were tested by immunoblotting to achieve high specificity. out of 300 sera, 22 reacted with transframe protein p30, 16 with the ribonucleoprotein p14, six with the envelope glycoprotein gp52 and three with the major core protein p27. reactivities to p30 and p14 were observed in sera from can ... | 1989 | 2553093 |
| reversible abrogation of il-3 dependence by an inducible h-ras oncogene. | immortalized, interleukin-3 (il-3)-dependent mouse mast cells (pb-3c) were transfected with a human activated c-h-ras gene under the transcriptional control of the mouse mammary tumor virus long terminal repeat. addition of increasing amounts of dexamethasone resulted in a concentration-dependent increase in expression of the h-ras oncogene. the elevation of p21 ras protein concentrations was paralleled by progressive growth of the transfectants in the absence of exogenous il-3, leading to compl ... | 1989 | 2555182 |
| glucocorticoid-regulated and constitutive trafficking of proteolytically processed cell surface-associated glycoproteins in wild type and variant rat hepatoma cells. | glucocorticoids regulate the trafficking of mouse mammary tumor virus (mmtv) glycoproteins to the cell surface in the rat hepatoma cell line m1.54, but not in the immunoselected sorting variant cr4. to compare the localization of mmtv glycoproteins to another proteolytically processed glycoprotein, both wild type m1.54 cells and variant cr4 cells were transfected with a human insulin receptor (hir) expression vector, prsvhir. the production of cell surface hir was monitored in dexamethasone-trea ... | 1989 | 2558298 |
| tumor-promoting phorbol ester and ras oncogene expression inhibit the glucocorticoid-dependent transcription from the mouse mammary tumor virus long terminal repeat. | oncogene activation has been suggested to play some role in determining the hormone independency of tumors. in order to study the role of protein kinase c in mediating the inhibition of the glucocorticoid-dependent transcription from the mouse mammary tumor virus (mmtv)-long terminal repeat induced by overexpressed activated ras oncogene, we studied the effects of protein kinase c activators [the tumor promoting phorbol ester 12-o-tetradecanoyl-phorbol-13-acetate (tpa)] and inhibitors [1-(5-isoq ... | 1989 | 2558300 |
| mapping contacts between unpurified human progesterone receptor and the hormone response element of mouse mammary tumor virus. | binding of steroid hormone receptors to specific recognition sites of hormone-inducible genes is one of the events required for hormonal regulation of gene transcription. we have employed an immunoprecipitation assay to map the interaction between unpurified human progesterone receptors from crude nuclear extracts of t47d cells and the hormone response element of the mouse mammary tumor virus (mmtv). dnase i footprints and methylation interference patterns are similar to those reported with high ... | 1989 | 2558865 |
| 5'-flanking dna of the human insulin receptor gene and long terminal repeat of mouse mammary tumour virus bind to the same nuclear protein(s). | the interaction of nuclear protein extracted from rat liver and 5'-flanking dna of the human insulin receptor gene was investigated with the aid of gel mobility shift analysis. when 5'-flanking dna (-1255/-1206 or -385/-345 base pairs) was incubated with nuclear protein, two or three 32p-dna species (protein binding dna fragment(s) and free dna fragment) were detected. these bands did not disappear in spite of increasing amounts of synthetic poly(di-dc), showing that nuclear protein binds specif ... | 1989 | 2558939 |
| an auto-inducible vector conferring high glucocorticoid inducibility upon stable transformant cells. | a new gene expression system in mammalian cells was developed by using the glucocorticoid receptor (gr) as an inducible positive feedback factor. mouse ltk- cells were transfected with plasmids carrying the gr-encoding gene and the lacz reporter gene, both of which were fused with the glucocorticoid-inducible enhancer/promotor of the mouse mammary tumor virus (mtv). the gr gene was first induced to supply the receptor protein, which further induced the expression of both gr and reporter genes. s ... | 1989 | 2558971 |
| [cloning and analysis of the primary structure of an element, related to the murine mammary cancer virus, from the genome of the djungarian hamster]. | 11 recombinant bacteriophages from the genomic library of djungarian hamster genome, that carry mmtv-related sequences (mrs-ps), have been cloned with the murine mammary cancer virus (mmtv) as a hybridization probe. the sequences are repeated 50 times in the genome. mrs-ps contain the tracts of homology with the long end repeat mmtv, the genes pol and, possibly, env, but not with the gag gene. sequencing of the 0,87 kb restrict, common to all ecori-bamhi clones, and the analysis of the sequence ... | 1989 | 2559324 |
| binding of steroid receptors to the hres of mouse mammary tumor virus, chicken and xenopus vitellogenin and rabbit uteroglobin genes: correlation with induction. | binding to hormone responsive elements (hre) is an essential step in gene regulation by steroid hormones. using a combination of in vivo and in vitro studies we have analyzed the interactions of the estrogen receptor with genes from three different systems: the long terminal repeat (ltr) of the mouse mammary tumor virus (mmtv), the chicken and xenopus vitellogenin genes and the rabbit uteroglobin gene. the estrogen receptor binds to all four genes in vitro, but the mmtv ltr does not respond to e ... | 1989 | 2560509 |
| the regulation of expression of mouse mammary tumor virus dna by steroid hormones and growth factors. | mouse mammary tumor virus (mmtv) expression is associated with hyperplastic alveolar growth and subsequent development of mammary cancers in the mouse. the expression of this virus is also controlled by factors involved in the normal proliferation and differentiation of the mammary epithelium. during pregnancy when the mammary gland undergoes massive proliferation, mmtv expression is increased. steroid hormones and growth factors that play an important role in the proliferation of mammary gland ... | 1989 | 2560510 |
| insulin enhances glucocorticoid induction of gene expression in a sequence specific manner. | glucocorticoid receptor (gr) induces transcriptional activation of specific genes by binding to cis-acting enhancer sequences termed glucocorticoid responsive elements (gres). insulin regulates gene transcription part of which is mediated sequences dominated by gres. by transient expression in htc cells of fusion gene consist mmtv 5' flanking sequences containing the gres on the thymidine kinase promoter (tk) and the coding region of the chloramphenicol acetyl transferase gene (cat), we demonstr ... | 1989 | 2560516 |
| endogenous virus genomes become hypomethylated tissue--specifically during aging process of c57bl mice. | in an attempt to find out a cause for age-dependent derepression of endogenous viruses, extents of dna methylation at the endogenous b- and c-type ecotropic viruses in brain, liver and spleen of c57bl/6njc1 were examined at three ages, newborn, young adult and old. both endogenous viruses showed a slight but significant tissue-specific either hypo- or hypermethylation during post-natal developmental phase in the three tissues. after maturation, however, no such change was detectable at most of t ... | 1989 | 2561001 |
| protein-dna interactions at steroid hormone regulated genes. | this work summarizes binding data that were obtained with partially purified glucocorticoid and progesterone receptors, as well as with a crude nuclear protein extract, to dna sequences in and around hormonally regulated genes. the sequence recognition by the glucocorticoid receptor at the different defined glucocorticoid regulatory elements (gre) is discussed and a consensus sequence formulated. a three dimensional representation gives an impression of the mode of interaction between the protei ... | 1989 | 2561356 |
| plasmid-aided insertion of mmtv-ltr and ras dnas to nih 3t3 fibroblast cells makes them responsive to 2,3,7,8-tcdd causing overexpression of p21ras and down-regulation of egf receptor. | tcdd administered to nih 3t3 fibroblast cells transfected with a plasmid containing mmtv-ltr and mouse ras dnas caused an increased level of p21ras protein and down-regulation of egf receptor. this effect occurred only in the cells with introduced n-ras or ha-ras under transcriptional control of glucocorticoid-sensitive mmtv-ltr but not ones without these dnas. the mmtv-ltr ras-incorporated cells treated with either dexamethasone or tcdd grew in soft agar to form colonies (anchorage independent ... | 1989 | 2562161 |
| e. coli ribosomes re-phase on retroviral frameshift signals at rates ranging from 2 to 50 percent. | many retroviruses express gag-pol or gag-pro-pol polypeptides by coupling their translation from overlapping reading frames with -1 ribosomal frameshifts. here, we show that the well-known ribosomal frameshift signals found in retroviral mrna will provoke escherichia coli ribosomes to shift frame in the same manner as their eukaryotic counterparts. ribosomes of e. coli respond in vivo to both the tandem slippery codons present at the retroviral frameshift site and the 3' flanking sequence. sligh ... | 1989 | 2562219 |
| retroviral-related genes, proto-oncogenes, and breast cancer. | | 1989 | 2562312 |
| oncogene mediated repression of glucocorticoid hormone response elements and glucocorticoid receptor levels. | we have previously described the inhibition of glucocorticoid-dependent transcription from the mouse mammary tumor virus long terminal repeat promoter by products of the h-ras and v-mos oncogenes. we have studied the effects of conditional oncogenes on expression of glucocorticoid-dependent indicator genes. expression of the glucocorticoid-dependent transcription of the tyrosine aminotransferase gene was monitored in fto-2b rat hepatoma cells during mr 21,000 protein (p21) h-ras induction. a str ... | 1989 | 2564809 |
| lymphomas with acquired mouse mammary tumor virus proviruses resemble distinct prethymic and intrathymic phenotypes defined in vivo. | a number of murine t cell lymphomas expressing the t cell ag thy-1 contain acquired mouse mammary tumor (mmtv) proviruses. these lymphomas all express detectable levels of mmtv rna, yet the majority of the tumors fail to produce mmtv particles. to determine if the ability of lymphomas to produce mmtv is a reflection of the differentiation state of the tumor, we examined eight lymphomas for expression of surface b and t cell ag as well as for rearrangements and expression of tcr genes. all tumors ... | 1989 | 2565355 |
| stochastic appearance of mammary tumors in transgenic mice carrying the mmtv/c-neu oncogene. | transgenic mice carrying the activated c-neu oncogene under the control of the mouse mammary tumor virus (mmtv) long terminal repeat were produced. epithelial hyperplasia of epididymis, seminal vesicles, and salivary glands, and dysplasia of harderian glands, were induced. moreover, in females of our four lines, independent but multiple mammary tumors arose asynchronously, between 5 and 10 months of age, as stochastic events. histologically, poorly differentiated adenocarcinomas, with intratumor ... | 1989 | 2567634 |
| expression of proteins immunologically related to murine mammary tumour virus (mmtv) core proteins in the cells of breast cancer continuous lines mcf-7, t47d, mda-231 and cells from human milk. | expression of antigens immunologically related to the gag gene products of murine mammary tumour virus (mmtv) in continuous cell lines mcf-7, t47d and mda-231 was followed by indirect enzyme immunoassay (eia). some cells of the 2 clonal lines derived from mcf-7 and t47d cells contained mmtv antigens, but these were not detected in mda-231 cells and in epithelial cells from the milk of healthy women. the expression of antigens related to mmtv gag proteins correlated with the expression of protein ... | 1989 | 2569809 |
| gross genetic differences among substrains of nzb mice. | substrains of nzb mice have been compared by southern blot analysis using several probes. the restriction fragment length polymorphism of probes derived from the igh-v, igk-v, tcr alpha-c loci and of the long terminal repeat of the mouse mammary tumour virus revealed that nzb/bllwptibm were grossly different from nzb/blnj and nzb/blola. comparison with mouse strains of the igk-v haplotypes a and d suggested that nzb/bllwptibm contain genetic material of the c58 mouse strain. | 1989 | 2575643 |
| heterogeneity of keratin expression in mouse mammary hyperplastic alveolar nodules and adenocarcinomas. | the keratins and other cytoskeletal proteins expressed by normal, preneoplastic, and malignant mammary tissues in balb/c mice and by cells in primary cultures established from these tissues were analyzed and compared. the preneoplastic lesions were hyperplastic alveolar nodules (han) derived originally from mice treated by hormonal stimulation (d2), exposed to a chemical carcinogen (c4), or spontaneously expressing mouse mammary tumor virus (cv2) and maintained by serial transplantation. all tum ... | 1985 | 2580627 |
| determination of type specific antigenic reactivities and quantitation of murine mammary tumor virus by elisa. | type specific differences associated with the antigenic determinants of exogenous and endogenous murine mammary tumor viruses (mumtvs) isolated from strain c3h(jax) and icrc were demonstrated by competition enzyme linked immunosorbent assay (elisa). in this assay, highly purified intact mumtv from the milk of strain c3h(jax) was conjugated to the enzyme penicillinase using glutaraldehyde. igg fraction of antiserum prepared against disrupted c3h (jax) mumtv was used in the competition elisa. the ... | 1985 | 2582283 |
| human progesterone receptor complexed with the antagonist ru 486 binds to hormone response elements in a structurally altered form. | structural and functional properties of human progesterone receptors (pr) bound with the antiprogestin, ru 486, and the progestin agonist, r5020, were compared in order to identify receptor mechanisms responsible for the inability of ru 486 to activate the transcriptional capacity of receptors. ru 486 interaction with human pr did not inhibit receptor transformation as assessed by dissociation of nontransformed 8-10s oligomeric receptors (in vitro and in vivo) and by tight binding of pr to nucle ... | 1989 | 2608048 |