| a novel, c-terminal dominant negative mutation of the gr causes familial glucocorticoid resistance through abnormal interactions with p160 steroid receptor coactivators. | primary cortisol resistance is a rare, inherited or sporadic form of generalized end-organ insensitivity to glucocorticoids. here, we report a kindred in which affected members had a heterozygous t to g base substitution at nucleotide 2373 of exon 9alpha of the gr gene, causing substitution of ile by met at position 747. this mutation was located close to helix 12, at the c terminus of the ligand-binding domain, which has a pivotal role in the formation of activation function (af)-2, a subdomain ... | 2002 | 12050230 |
| ectopic expression of the ets transcription factor er81 in transgenic mouse mammary gland enhances both urokinase plasminogen activator and stromelysin-1 transcription. | the pea3 group members pea3, er81 and erm, which are highly conserved transcription factors from the ets family, are over-expressed in metastatic mammary tumors. in the current study, we present the characterization of a transgenic mouse strain which over-expresses er81 in the mammary gland via the long terminal repeat of the mouse mammary tumor virus (ltr-mmtv). although six genotypically positive transgenic lines were identified, only one expressed the ectopic transcript with an exclusive expr ... | 2002 | 12054346 |
| loss of androgen receptor transcriptional activity at the g(1)/s transition. | androgens are essential for the differentiation, growth, and maintenance of male-specific organs. the effects of androgens in cells are mediated by the androgen receptor (ar), a member of the nuclear receptor superfamily of transcription factors. recently, transient transfection studies have shown that overexpression of cell cycle regulatory proteins affects the transcriptional activity of the ar. in this report, we characterize the transcriptional activity of endogenous ar through the cell cycl ... | 2002 | 12055183 |
| deletion of t cells bearing the v beta8.1 t-cell receptor following mouse mammary tumor virus 7 integration confers resistance to murine cerebral malaria. | plasmodium berghei anka induces a fatal neurological syndrome known as cerebral malaria (cm) in susceptible mice. host genetic elements are among the key factors determining susceptibility or resistance to cm. analysis of mice of the same h-2 haplotype revealed that mouse mammary tumor virus 7 (mtv-7) integration into chromosome 1 is one of the key factors associated with resistance to neurological disease during p. berghei anka infection. we investigated this phenomenon by infecting a series of ... | 2002 | 12065512 |
| blockade of tgf-beta inhibits mammary tumor cell viability, migration, and metastases. | tgf-betas are potent inhibitors of epithelial cell proliferation. however, in established carcinomas, autocrine/paracrine tgf-beta interactions can enhance tumor cell viability and progression. thus, we studied the effect of a soluble fc:tgf-beta type ii receptor fusion protein (fc:tbetarii) on transgenic and transplantable models of breast cancer metastases. systemic administration of fc:tbetarii did not alter primary mammary tumor latency in mmtv-polyomavirus middle t antigen transgenic mice. ... | 2002 | 12070302 |
| lifetime exposure to a soluble tgf-beta antagonist protects mice against metastasis without adverse side effects. | tgf-betas play diverse and complex roles in many biological processes. in tumorigenesis, they can function either as tumor suppressors or as pro-oncogenic factors, depending on the stage of the disease. we have developed transgenic mice expressing a tgf-beta antagonist of the soluble type ii tgf-beta receptor:fc fusion protein class, under the regulation of the mammary-selective mmtv-ltr promoter/enhancer. biologically significant levels of antagonist were detectable in the serum and most tissue ... | 2002 | 12070308 |
| prevalence of 52-kd and 60-kd ro/ss-a autoantibodies in japanese patients with polymyositis/dermatomyositis. | to determine the prevalence of 52-kd and 60-kd ro/ss-a antibodies in japanese patients with polymyositis/dermatomyositis, we examined serum samples from 61 patients with pm/dm, 10 patients with primary sjögren's syndrome, and 25 healthy control subjects. six serum samples possessed anti-ro/ss-a antibodies and were positive for anti-ro52, anti-ro60, or both. two reacted with both ro52 and ro60, and 4 reacted with ro52 alone. the results suggest that ro52 is the main antigen of anti-ro/ss-a antibo ... | 2002 | 12077598 |
| the role of phenylalanine-119 of the reverse transcriptase of mouse mammary tumour virus in dna synthesis, ribose selection and drug resistance. | phe-119 in the reverse transcriptase (rt) of mouse mammary tumour virus (mmtv) is homologous with tyr-115 in hiv type 1 (hiv-1) rt and to phe-155 in murine leukaemia virus (mlv) rt. by mutating these residues in hiv-1 and mlv rts (which are strict dna polymerases) the enzymes were shown to function also as rna polymerases. owing to the uniqueness of mmtv as a type b retrovirus, we have generated a phe-119-val mutant of mmtv rt to study the involvement of this residue in affecting the catalytic f ... | 2002 | 12097136 |
| jun dimerization protein 2 functions as a progesterone receptor n-terminal domain coactivator. | the progesterone receptor (pr) contains two transcription activation function (af) domains, constitutive af-1 in the n terminus and af-2 in the c terminus. af-2 activity is mediated by a hormone-dependent interaction with a family of steroid receptor coactivators (srcs). src-1 can also stimulate af-1 activity through a secondary domain that interacts simultaneously with the primary af-2 interaction site. other protein interactions and mechanisms that mediate af-1 activity are not well defined. b ... | 2002 | 12101239 |
| can mmtv exploit tlr4? | the recognition of microbial pathogens based on their molecular patterns is essential for host defense. recently, toll-like receptors have been shown not only to recognize viruses as well as bacteria and fungi, but also to trigger an efficient immune response. a recent publication proposed that the retrovirus mouse mammary tumor virus exploits the pattern-recognition receptor toll-like receptor 4 to achieve more efficient infection. | 2002 | 12110201 |
| trans-activation and repression properties of the novel nonsteroid glucocorticoid receptor ligand 2,5-dihydro-9-hydroxy-10-methoxy-2,2,4-trimethyl-5-(1-methylcyclohexen-3-y1)-1h-[1]benzopyrano[3,4-f]quinoline (a276575) and its four stereoisomers. | glucocorticoids are potent anti-inflammatory and immunosuppressant agents. however, they also produce serious side effects that limit their usage. it has been proposed that anti-inflammatory properties of glucocorticoids are caused mostly by repression of activator protein 1- and nuclear factor kappabeta-stimulated synthesis of inflammatory mediators, whereas most of their adverse effects are associated with trans-activation of genes involved with metabolic processes. our laboratories have sough ... | 2002 | 12130681 |
| inducible expression of fgf-3 in mouse mammary gland. | fibroblast growth factor-3 (fgf-3) is a crucial developmental regulator. aberrant activation of this gene by mouse mammary tumor virus insertion results in pregnancy-responsive mammary tumorigenesis. to characterize better fgf-3 function in postnatal mammary gland development and cancer initiation/progression, we used a mifepristone (ru486)-inducible regulatory system to express conditionally fgf-3 in the mammary epithelium of transgenic mice. ectopic overexpression of fgf-3 in pubescent mammary ... | 2002 | 12169667 |
| [effect of 5-azacytidine on expression of dna sequences homologous to env gene of murine mammary tumor virus in normal human lymphocytes]. | expression of dna sequences, related to mmtv env gene, in peripheral blood lymphocytes, which was strictly specific for human mammary carcinoma, has been previously reported. these sequences (homologous to env gene site coding for mmtv gp52 envelope antigen) expressed in t cells can play the key role in virus infection transmission and propagation. in order to elucidate the possible routes of env mmtv-homologous sequences expression, we tried to induced it in donot t lymphocytes by various metho ... | 2002 | 12180024 |
| tef-1 transcription factors regulate activity of the mouse mammary tumor virus ltr. | the mouse mammary tumor virus long terminal repeat (ltr) is a potent transcriptional enhancer. we identified several putative binding sites for the tef-1 family of transcription factors (tef-1, rtef-1, dtef-1, and etf) in the proximal negative regulatory element of the ltr. gel mobility shift assays revealed strong tef-1 factor binding to one site using nuclear extracts from cv-1 cells and from the human breast cancer cell line mcf-7. mutation of this site increased basal activity of the ltr. in ... | 2002 | 12207913 |
| human breast cancer and lymphomas may share a common aetiology involving mouse mammary tumour virus (mmtv). | mouse mammary tumour virus (mmtv) causes breast tumours in mice, and has been implicated in the aetiology of murine lymphomas. several recent human studies have detected mmtv-env dna sequences in 30-40% of tumours from breast cancer patients but in less than 4% of normal breast tissue. mmtv dna has been detected in simultaneously diagnosed primary lymphoma and breast cancer tissue, suggesting mmtv may be involved in the aetiology of both breast cancer and lymphoma. we further hypothesize that if ... | 2002 | 12208195 |
| characterization of deoxyuridine 5'-triphosphate nucleotidohydrolase from trypanosoma cruzi. | we report the cloning and kinetic characterization of trypanosoma cruzi deoxyuridine 5'-triphosphate nucleotidohydrolase (dutpase) whose coding sequence was isolated by genetic complementation in escherichia coli. the deduced amino acid sequence was similar to leishmania major dutpase although it exhibits an amino acid insertion which is sensitive to protease inactivation. the catalytically active species of the enzyme is a dimer and a detailed kinetic characterization showed that it is highly s ... | 2002 | 12208522 |
| human immunodeficiency virus type 1 (hiv-1) accessory protein vpr induces transcription of the hiv-1 and glucocorticoid-responsive promoters by binding directly to p300/cbp coactivators. | the accessory vpr protein of human immunodeficiency virus type 1 (hiv-1) is a promiscuous activator of viral and cellular promoters. we report that vpr enhances expression of the glucocorticoid receptor-induced mouse mammary tumor virus (mmtv) promoter and of the tat-induced hiv-1 long terminal repeat promoter by directly binding to p300/cbp coactivators. in contrast, vpr does not bind to p/caf or to members of the p160 family of nuclear receptor coactivators, such as steroid receptor coactivato ... | 2002 | 12208951 |
| conditional over-expression of estrogen receptor alpha in a transgenic mouse model. | attempts to delineate the mechanisms of estrogen action have promoted the creation of several estrogen receptor alpha (eralpha) mouse models in the past decade. these traditional models are limited by the fact that the receptors are either absent or present throughout all stages of development. the purpose of this work was to develop a conditional transgenic model that would provide an in vivo method of controlling the spatial and temporal regulation of eralpha expression. the tetracycline respo ... | 2002 | 12212839 |
| glucocorticoids modulate transformation by v-src in a cell-specific manner. | in balb 3t3 murine fibroblasts infected with retroviruses carrying the v-src oncogene, treatment with the glucocorticoid hormone dexamethasone induces a 10-fold increase in the number of transformed foci and of anchorage-independent colonies. in contrast, in nih-3t3-infected cells the number of foci and of colonies growing in soft agar is considerably reduced by the addition of the hormone. the effect of dexamethasone on both balb 3t3 and nih 3t3 cells is dose-dependent and mediated by specific ... | 2002 | 12213218 |
| mouse transferrin receptor 1 is the cell entry receptor for mouse mammary tumor virus. | enveloped viruses enter cells by binding to their entry receptors and fusing with the membrane at the cell surface or after trafficking through acidic endosomal compartments. species-specific virus tropism is usually determined by these entry receptors. because mouse mammary tumor virus (mmtv) is unable to infect chinese hamster cells, we used phenotypic screening of the t31 mouse/hamster radiation hybrid panel to map the mmtv cell entry receptor gene and subsequently found that it is transferri ... | 2002 | 12218182 |
| weight-cycling decreases incidence and increases latency of mammary tumors to a greater extent than does chronic caloric restriction in mouse mammary tumor virus-transforming growth factor-alpha female mice. | multiple periods of caloric restriction (or fasting)/refeeding in rodents have had inconsistent effects on mammary tumor (mt) development. in the present study, the consequence of intermittent caloric restriction/refeeding resulting in weight-cycling was evaluated using an oncogene-induced mt mouse model. hybrid mouse mt virus-transforming growth factor alpha (mmtv-tgf-alpha)/lep(+)lep(ob) female mice were used. ad libitum-fed mice (n = 30) were fed american institute of nutrition (ain)-93m diet ... | 2002 | 12223427 |
| [the possibility of the retroviruses participation in human breast neoplasm induction]. | the existence of retrovirus related to murine mammary tumor virus (mmtv) and specifically associated with mammary carcinoma has been suggested long ago. this review covers some papers published in the 70-80ies until now, containing evidence for this suggestion. in spite of a lack of direct proof of virus existence this problem still remains to be solved. there are some indications that both in man and in mice, peripheral blood lymphocytes participate in the circulation of the supposed viral agen ... | 2002 | 12271725 |
| [detection of murine mammary tumor virus (mmtv) env gene-like sequences in breast cancer from argentine patients]. | in the last years research on the possible viral etiology of human breast cancer has been revised. previous studies have demonstrated the presence of a mouse mammary tumor virus (mmtv) env gene-like sequence in about 38% of breast cancers from american and italian women; these sequences are generally absent in other tumors and in normal mammary tissue. in the present study we have analyzed the presence of a 250-bp sequence of the mmtv env gene in breast cancer biopsies from argentine patients. t ... | 2002 | 12325488 |
| origin and progression of pregnancy-dependent mammary tumors induced by new mouse mammary tumor virus variants. | in order to study mechanisms of progression of mouse mammary tumor virus (mmtv)-induced pregnancy-dependent mammary lesions, we removed and serially transplanted 17 small tumors detected in mmtv-infected pregnant females. this gave rise to the same number of 'in vivo' tumor lines. hormone-dependency of the passages was determined by comparing tumor development in multiparous versus virgin hosts. we found that the first passages of most of these lesions (11/17) required pregnancy to grow. however ... | 2002 | 12353808 |
| celecoxib, a selective cyclooxygenase 2 inhibitor, protects against human epidermal growth factor receptor 2 (her-2)/neu-induced breast cancer. | cyclooxygenase 2 (her-2) (cox-2), an inducible form of cox, is overexpressed in her-2/neu-positive human breast cancers. the aim of this study was to determine whether celecoxib, a selective cox-2 inhibitor, protected against her-2/neu-induced experimental breast cancer. cox-2 protein was detected in breast carcinomas from mouse mammary tumor virus (mmtv)/neu mice. treatment with celecoxib (500 ppm) significantly reduced the incidence of mammary tumors in mmtv/neu mice (p = 0.003) and caused abo ... | 2002 | 12359744 |
| matrilysin (matrix metalloproteinase-7) selects for apoptosis-resistant mammary cells in vivo. | overexpression of the matrix metalloproteinase matrilysin (matrix metalloproteinase-7) in the mouse mammary gland promotes mammary hyperplasia and accelerates the onset of oncogene-induced mammary tumors. in cell culture models, acute exposure of cells coexpressing fas and fas ligand (fasl) to matrilysin induces apoptosis, whereas chronic exposure to matrilysin selects for apoptosis-resistant cells. we now demonstrate that matrilysin promotes resistance to apoptosis in vivo. matrilysin expressio ... | 2002 | 12359768 |
| differential activation of the ikappabalpha and mouse mammary tumor virus promoters by progesterone and glucocorticoid receptors. | the glucocorticoid and progesterone receptors (gr and pr) are structurally homologous and bind a common hormone response element (hre). the mechanisms by which receptors activate specific promoters when multiple steroids are present in a cell is a critical question in endocrinology. to investigate how co-existing steroid receptors regulate gene transcription, we have compared two hormone-responsive promoters in t47d/a1-2 human breast cancer cells expressing both the gr and pr. the promoters chos ... | 2002 | 12361720 |
| regions of mouse mammary tumor virus superantigen involved in interaction with the major histocompatibility complex class ii i-a molecule. | to study the major histocompatibility complex class ii i-e dependence of mouse mammary tumor virus (mmtv) superantigens, we constructed hybrids between the i-e-dependent mmtv(gr) and the i-e-independent mtv-7 superantigens and tested them in vivo. our results suggest that, although the c-terminal third mediates i-a interaction, additional binding sites are located elsewhere in the superantigen. | 2002 | 12368363 |
| soy isoflavones increase latency of spontaneous mammary tumors in mice. | soy protein, with and without isoflavones, is being added to foods by manufacturers in response to the food and drug administration (fda)-approved health claim for cardiovascular protection. furthermore, soy isoflavones are increasingly consumed by women in the united states as an alternative to hormone replacement therapy. the role of these phytoestrogens in breast cancer is controversial. although exposure of rodents to soy isoflavones during the perinatal period appears to reduce mammary canc ... | 2002 | 12368416 |
| antagonism of glucocorticoid receptor transactivity and cell growth inhibition by transforming growth factor-beta through ap-1-mediated transcriptional repression. | we have examined the interaction of the glucocorticoid receptor (gr) and transforming growth factor-beta (tgf-beta) signal pathways because of their mutual involvement in the regulation of cell growth, development and differentiation. most studies of this cross-talk event have focused on the effects of glucocorticoids (gcs) on tgf-beta responses. in this work, we show that tgf-beta can antagonize dexamethasone (dex)-mediated growth suppression in mouse fibrosarcoma l929 cells. tgf-beta also repr ... | 2002 | 12379279 |
| perturbation of beta1-integrin function in involuting mammary gland results in premature dedifferentiation of secretory epithelial cells. | to study the mechanism of beta1-integrin function in vivo, we have generated transgenic mouse expressing a dominant negative mutant of beta1-integrin under the control of mouse mammary tumor virus (mmtv) promoter (mmtv-beta1-cyto). mammary glands from mmtv-beta1-cyto transgenic females present significant growth defects during pregnancy and lactation and impaired differentiation of secretory epithelial cells at the onset of lactation. we report herein that perturbation of beta1-integrin function ... | 2002 | 12388754 |
| the specific anti-cancer activity of green tea (-)-epigallocatechin-3-gallate (egcg). | the effect of the green tea polyphenol-(-)epigallocatechin-3-gallate (egcg) was tested in cultures of normal and transformed nih-patm ras fibroblasts. in this system transformation can be induced at will by the addition of dexamethasone, which induces the expression of h- ras by activating the mammary tumor virus long terminal repeat (mmtv-ltr) promoter. this facilitates a reliable comparison of the susceptibility of normal and transformed cells to egcg. it has been shown that egcg inhibited the ... | 2002 | 12395181 |
| mouse mammary tumor-like env gene as a molecular marker for breast cancer? | | 2002 | 12397656 |
| chlorpromazine inhibits the glucocorticoid receptor-mediated gene transcription in a calcium-dependent manner. | antipsychotic drugs can modulate transcription factors and also nuclear receptors, but their action on glucocorticoid receptors (gr)-members of the steroid/thyroid hormone receptor family has not been studied so far. in the present study we investigated effects of various antipsychotics on the glucocorticoid-mediated gene transcription in fibroblast cells, stably transfected with a mouse mammary tumor virus promoter (lmcat cells). chlorpromazine (3-100 microm) inhibited the corticosterone-induce ... | 2002 | 12423673 |
| mammary stem cell repertoire: new insights in aging epithelial populations. | the proliferative lifespan of mammary stem cells was examined in serially transplanted clonal-dominant epithelial populations. five successive transplant generations were done. the epithelial cell number in each outgrowth expands approximately 500-fold in nulliparous hosts and approximately 10000-fold in impregnated hosts. despite this, all resulting mammary outgrowths showed lineal identity with the original. growth senescence was observed in some implants beginning at the third generation in i ... | 2002 | 12425957 |
| initiation site binding protein and the initiator-like promoter element of mouse mammary tumor virus. | the mouse mammary tumor virus (mmtv) promoter contains an element near its transcription initiation site that is recognized by a protein termed initiation site binding protein (isbp). spacing between the tata box and the isbp site is important for mmtv promoter function, as altered spacing results in heterogeneity in start site selection in vitro and in vivo. the sequence of the isbp site is related to initiator elements common in many rna polymerase ii promoters. however, binding of partially p ... | 2002 | 12429527 |
| wnt and fgf gene clusters (review). | mouse mammary tumor virus (mmtv) is a retrovirus, activating wnt genes (wnt1/int-1, wnt3/int-4, wnt10b), fgf genes (fgf3/int-2, fgf4, fgf8) and other genes (notch4/int-3, eif3s6/int-6) due to proviral integration. among 19 wnt genes, wnt3 and wnt14b genes are clustered in human chromosome 17q21, wnt3a and wnt14 in human chromosome 1q42, wnt10a and wnt6 in human chromosome 2q35, and wnt10b and wnt1 in human chromosome 12q13. among 22 fgf genes, fgf19, fgf4 and fgf3 genes are clustered in human ch ... | 2002 | 12429977 |
| expression of a truncated brca1 protein delays lactational mammary development in transgenic mice. | to address the hypothesis that certain disease-associated mutants of the breast-ovarian cancer susceptibility gene brca1 have biological activity in vivo, we have expressed a truncated brca1 protein (trbrca1) in cell-lines and in the mammary gland of transgenic mice. immunofluorescent analysis of transfected cell-lines indicates that trbrca1 is a stable protein and that it is localized in the cell cytoplasm. functional analysis of these cell-lines indicates that expression of trbrca1 confers an ... | 2002 | 12437078 |
| the retinoid x receptor-selective retinoid, lgd1069, prevents the development of estrogen receptor-negative mammary tumors in transgenic mice. | despite the effectiveness of the selective estrogen receptor (er) modulators in preventing er-positive breast cancer, chemopreventive agents still need to be developed for the prevention of er-negative breast cancers. the naturally occurring retinoids are promising agents for the prevention of human cancers but are too toxic for long-term chronic use. we previously demonstrated that the chemopreventive effects of the retinoids could be separated from the toxicity by using an rxr-selective retino ... | 2002 | 12438218 |
| protein kinase ck2 promotes aberrant activation of nuclear factor-kappab, transformed phenotype, and survival of breast cancer cells. | the her-2/neu oncogene, the second member of the epidermal growth factor (egf) receptor family, encodes a transmembrane tyrosine kinase receptor. overexpression of her-2/neu in approximately 30% of breast cancers is associated with poor overall survival. recently, we have found that her-2/neu activates nuclear factor (nf)-kappab via a phosphatidylinositol 3 kinase (pi3-k)-akt kinase signaling pathway in mouse mammary tumor virus (mmtv)-her-2/neu nf639 mouse breast cancer cells. surprisingly, the ... | 2002 | 12438279 |
| asymmetric binding of histone h1 stabilizes mmtv nucleosomes and the interaction of progesterone receptor with the exposed hre. | packaging of mouse mammary tumor virus (mmtv) promoter sequences in nucleosomes modulates access of dna binding proteins and influences the interaction among dna bound transcription factors. here we analyze the binding of histone h1 to mmtv mononucleosomes assembled with recombinant histones and study its influence on nucleosome structure and stability as well as on progesterone receptor (pr) binding to the hormone responsive elements (hres). the mmtv nucleosomes can be separated into three main ... | 2002 | 12445785 |
| dynamic behavior of transcription factors on a natural promoter in living cells. | through the use of photobleaching techniques, we examined the dynamic interaction of three members of the transcription apparatus with a target promoter in living cells. the glucocorticoid receptor (gr) interacting protein 1 (grip-1) exhibits a half maximal time for fluorescent recovery (tau(r)) of 5 s, reflecting the same rapid exchange as observed for gr. in contrast, the large subunit (rpb1) of rna polymerase ii (pol ii) required 13 min for complete fluorescence recovery, consistent with its ... | 2002 | 12446572 |
| heparin-binding epidermal growth factor-like growth factor stimulates androgen-independent prostate tumor growth and antagonizes androgen receptor function. | peptide growth factors have been implicated in progression of prostate cancer (pca) to the androgen-independent state; however, much of the evidence linking diffusible mitogens and survival factors to this process remains circumstantial. heparin-binding epidermal growth factor-like growth factor (hb-egf), a prostate stroma-derived factor, promotes survival, proliferation, and neuroendocrine differentiation of androgen-dependent lncap pca cells in vitro. to test whether sustained exposure to hb-e ... | 2002 | 12446587 |
| attenuation of glucocorticoid signaling through targeted degradation of p300 via the 26s proteasome pathway. | the effects of acetylation on gene expression are complex, with changes in chromatin accessibility intermingled with direct effects on transcriptional regulators. for the nuclear receptors, both positive and negative effects of acetylation on specific gene transcription have been observed. we report that p300 and steroid receptor coactivator 1 interact transiently with the glucocorticoid receptor and that the acetyltransferase activity of p300 makes an important contribution to glucocorticoid re ... | 2002 | 12456802 |
| genes involved in breast cancer progression: analysis of global changes in gene expression or retroviral tagging? | | 2002 | 12466111 |
| acceleration of mouse mammary tumor virus-induced murine mammary tumorigenesis by a p53 172h transgene: influence of fvb background on tumor latency and identification of novel sites of proviral insertion. | we previously showed that a mammary-specific dominant-negative p53 transgene (wap-p53(172h)) could accelerate erbb2-induced mammary tumorigenesis in mice, but was not tumorigenic on its own. to identify other genes that cooperate with wap-p53(172h) in tumorigenesis, we performed mouse mammary tumor virus (mmtv) proviral mutagenesis. we derived f1, n2, and n4/n5 mice from p53(172h) transgenic fvb mice backcrossed onto mmtv+ c3h/he mice. results show the latency of mmtv tumorigenesis is correlated ... | 2002 | 12466138 |
| tsg101 is essential for cell growth, proliferation, and cell survival of embryonic and adult tissues. | tumor susceptibility gene 101 (tsg101) was identified in a random mutagenesis screen for potential tumor suppressors in nih 3t3 cells. altered transcripts of this gene have been detected in sporadic breast cancers and many other human malignancies. however, the involvement of this gene in neoplastic transformation and tumorigenesis is still elusive. using gene targeting, we generated genetically engineered mice with a floxed allele of tsg101. we investigated essential functions of this gene in v ... | 2003 | 12482969 |
| flow cytometric detection of mmtv superantigens. | | 2003 | 12489453 |
| regulation of transcription by the heterogeneous nuclear ribonucleoprotein e1b-ap5 is mediated by complex formation with the novel bromodomain-containing protein brd7. | e1b-ap5 was initially identified as a target of the early adenovirus e1b-55 kda protein during the course of lytic infection. e1b-ap5 belongs to the heterogeneous nuclear ribonucleoprotein family and was demonstrated to be involved in mrna processing and transport [gabler, schutt, groitl, wolf, shenk and dobner (1998) j. virol. 72, 7960-7971]. in the present paper, we demonstrate that e1b-ap5 differentially regulates basic and ligand-dependent transcription. we found that e1b-ap5 represses basic ... | 2003 | 12489984 |
| regulation of mouse mammary tumor virus env transcriptional activator initiated mammary tumor virus superantigen transcripts in lymphomas of sjl/j mice: role of ikaros, demethylation, and chromatin structural change in the transcriptional activation of mammary tumor virus superantigen. | mammary tumor virus (mtv29)-encoded superantigen expressed by sjl/j mouse b cell lymphomas stimulates cd4+v16+ t cells and thereby acquires t cell help necessary for lymphoma growth. mtv29 mouse mammary tumor virus env transcriptional activator (meta) env-controlled mtv29 superantigen (vsag29) mrna transcripts (1.8 kb) are not expressed in normal b or other somatic cells. real-time pcr-based assays with dna from normal sjl liver and vsag29- lymphoma (cnj101), digested with methylation-sensitive ... | 2003 | 12496403 |
| gfp expression in the mammary gland for imaging of mammary tumor cells in transgenic mice. | to examine the behavior of tumor cells in tumors developing directly from mammary tissue in transgenic models, we have evaluated transgenic mice expressing green fluorescent protein (gfp). using the mouse mammary virus promoter (mmtv) to directly drive expression of gfp, we find low levels of fluorescence in the mammary and salivary glands of transgenic animals. using mmtv-cre or wap-cre in combination with the cre-activatable cag-cat-egfp construct, we find stronger expression of gfp that is st ... | 2002 | 12499251 |
| cell type-dependent divergence of transactivation by glucocorticoid receptor ligand. | the glucocorticoid receptor regulates gene expression mainly by two mechanisms; transactivation and trans-repression. a ligand with strong transrepression and weak transactivation activity is predicted to be a beneficial agent with potent anti-inflammatory activity and minor adverse effects. recently, the profile of a synthetic steroid, ru24858, has been reported to fulfill this condition in vitro, but others have reported no dissociation between the anti-inflammatory activity and side effects i ... | 2002 | 12499651 |
| the role of neutralizing antibodies for mouse mammary tumor virus transmission and mammary cancer development. | mouse mammary tumor virus (mmtv) infection establishes chronic germinal centers and a lifelong neutralizing ab response. we show that removal of the draining lymph node after establishment of the germinal center reaction led to complete loss of neutralizing abs despite comparable infection levels in peripheral lymphocytes. importantly, in the absence of neutralization, only the exocrine organs mammary gland, salivary gland, pancreas, and skin showed strikingly increased infection, resulting in a ... | 2003 | 12502785 |
| modeling human breast cancer metastasis in mice: maspin as a paradigm. | breast cancer is the most common cancer detected in women, accounting for nearly one out of every three cancers diagnosed in the united states. most cancer patients do not die from the primary tumor but die due to metastasis. therefore, the study of metastasis is of most importance both to the clinician and patient. in the past, animal models have been used in breast cancer research and mammary gland biology. our group has also established several animal models to address the function of a novel ... | 2003 | 12507299 |
| epithelial and fibroblast cell lines derived from a spontaneous mammary carcinoma in a mmtv/neu transgenic mouse. | female murine mammary tumor virus (mmtv)/neu transgenic mice, expressing a wild-type rat neu oncogene driven by an mmtv promoter, develop focal mammary adenocarcinomas that are pathologically very similar to human breast tumors. two new cell lines were established from a mammary tumor that arose in a female mmtv/neu transgenic mouse. one of these lines, mammary carcinoma from neu transgenic mouse a (mcneua), has an epithelial morphology, is cytokeratin positive, and expresses high levels of the ... | 2002 | 12513120 |
| nuclear factor 1 is required for both hormone-dependent chromatin remodeling and transcriptional activation of the mouse mammary tumor virus promoter. | the mouse mammary tumor virus (mmtv) promoter has been used as a model to study how the glucocorticoid receptor (gr) remodels chromatin to allow other transcription factors to bind and activate transcription. to dissect the precise role of nuclear factor 1 (nf1) in chromatin remodeling and transcriptional activation, we used linker-scanning mutants of transcription factor binding sites on the mmtv promoter. we compared the nf1 mutant mmtv promoter in the context of transiently transfected templa ... | 2003 | 12529394 |
| unique resistance of i/lnj mice to a retrovirus is due to sustained interferon gamma-dependent production of virus-neutralizing antibodies. | selection of immune escape variants impairs the ability of the immune system to sustain an efficient antiviral response and to control retroviral infections. like other retroviruses, mouse mammary tumor virus (mmtv) is not efficiently eliminated by the immune system of susceptible mice. in contrast, mmtv-infected i/lnj mice are capable of producing igg2a virus-neutralizing antibodies, sustain this response throughout their life, and secrete antibody-coated virions into the milk, thereby preventi ... | 2003 | 12538662 |
| embryonal mass and hormone-associated effects of pregnancy inducing a differential growth of four murine tumors. | a differential effect of pregnancy on the growth of subcutaneous implants of four murine tumors has been observed. two tumors lacking receptors for progesterone and estrogen [methylcholanthrene-induced fibrosarcoma (mc-c) and spontaneous lymphoid leukemia (lb)] exhibited slow kinetics throughout the course of pregnancy, although inhibition was stronger beyond day 10. on the other hand, one of two tumors bearing receptors for progesterone and estrogen [medroxyprogesterone (mpa)-induced mammary ad ... | 2002 | 12549624 |
| histone h1 enhances synergistic activation of the mmtv promoter in chromatin. | minichromosomes assembled on the mouse mammary tumor virus (mmtv) promoter in vitro exhibit positioned nucleosomes, one of which covers the binding sites for progesterone receptor (pr) and nuclear factor 1 (nf1). incorporation of histone h1 into mmtv minichromosomes improves the stability of this nucleosome and decreases basal transcription from the mmtv promoter, as well as its response to either pr or nf1. however, histone h1-containing minichromosomes display better pr binding and support a m ... | 2003 | 12554659 |
| mouse wnt9b transforming activity, tissue-specific expression, and evolution. | the members of the wnt family of secreted factors have oncogenic potential and important roles as developmental regulators. we report an analysis of mouse wnt9b (also called wnt15 and wnt14b), including its cdna sequence, chromosomal mapping, epithelial cell transforming activity, adult and embryonic tissue expression patterns, and evolution. we also deduced the full-length amino acid sequence of its close relative, wnt9a (also called wnt14), from unannotated genomic dna sequences in genbank. fu ... | 2003 | 12573259 |
| potential action of igf-1 and egf on androgen receptor nuclear transfer and transactivation in normal and cancer human prostate cell lines. | this work was designed to determine whether igf-1 and egf modulate nuclear transfer and transactivation of the androgen receptor (ar) in human prostate cell lines (pnt1a and du-145). we first characterized the igf-1 and egf receptors by ligand-binding assays with [125i] igf-1 and [125i] egf in a normal human prostate epithelial cell line, pnt1a. we then evaluated the effects of these growth factors on ar nuclear transfer and transcriptional activation in this cell line and in du-145, a human pro ... | 2002 | 12573820 |
| selective removal of the selenocysteine trna [ser]sec gene (trsp) in mouse mammary epithelium. | mice homozygous for an allele encoding the selenocysteine (sec) trna [ser]sec gene (trsp) flanked by loxp sites were generated. cre recombinase-dependent removal of trsp in these mice was lethal to embryos. to investigate the role of trsp in mouse mammary epithelium, we deleted this gene by using transgenic mice carrying the cre recombinase gene under control of the mouse mammary tumor virus (mmtv) long terminal repeat or the whey acidic protein promoter. while both promoters target cre gene exp ... | 2003 | 12588969 |
| p53-independent response to cisplatin and oxaliplatin in mmtv-ras mouse salivary tumors. | a transgenic mouse tumor model was used to investigate the role of p53 in tumor response to two different platinum-based chemotherapeutic agents: (a) cisplatin and (b) oxaliplatin, a diaminocyclohexane platine recently introduced into the clinic. mmtv-v-ha-ras transgenic mice were interbred to p53-deficient mice to generate mice that develop salivary tumors either possessing or lacking p53. tumor-bearing mice were then treated on either a 9-day schedule to assess overall tumor growth response or ... | 2003 | 12589033 |
| anabolic steroids, testosterone-precursors and virilizing androgens induce distinct activation profiles of androgen responsive promoter constructs. | different androgens, e.g. virilizing androgens such as testosterone and its precursors as well as synthetic anabolic steroids, respectively, induce diverse biological effects. the molecular basis for this variety in biological actions, however, is not well understood. we hypothesized that this variability of actions may be due to steroid-specific target gene expression profiles following androgen receptor (ar)-activation. therefore, we investigated androgen receptor dependent transactivation of ... | 2002 | 12589933 |
| promyelocytic leukemia protein (pml) functions as a glucocorticoid receptor co-activator by sequestering daxx to the pml oncogenic domains (pods) to enhance its transactivation potential. | daxx has been reported to function as a transcriptional modulator in the nucleus. in the present study, we have explored the role of daxx in regulating the transcriptional activity of the glucocorticoid receptor (gr). overexpression of daxx suppressed gr-mediated activation of the mouse mammary tumor virus promoter in cos-1, hela, and 293t cells. in vitro and in vivo studies revealed that daxx could directly bind to gr. the mapping analysis further demonstrated that the c-terminal region of daxx ... | 2003 | 12595526 |
| genetically obese mmtv-tgf-alpha/lep(ob)lep(ob) female mice do not develop mammary tumors. | elevated body weight is a risk factor for postmenopausal breast cancer and is associated with increased incidence of spontaneous and chemically induced mammary tumors (mts) in rodents. in this study, genetically obese lep(ob)lep(ob) female mice that overexpress human tgf-alpha (transforming growth factor-alpha) were used to assess the role of body weight on oncogene-induced mt development in comparison to lean counterparts. mmtv (mouse mammary tumor virus)-tgf-alpha and lep strain mice were cros ... | 2003 | 12602920 |
| retroviruses have differing requirements for proteasome function in the budding process. | proteasome inhibitors reduce the budding of human immunodeficiency virus types 1 (hiv-1) and 2, simian immunodeficiency virus, and rous sarcoma virus. to investigate this effect further, we examined the budding of other retroviruses from proteasome inhibitor-treated cells. the viruses tested differed in their gag organization, late (l) domain usage, or assembly site from those previously examined. we found that proteasome inhibition decreased the budding of murine leukemia virus (plasma membrane ... | 2003 | 12610113 |
| the type b leukemogenic virus truncated superantigen is dispensable for t-cell lymphomagenesis. | type b leukemogenic virus (tblv) is a variant of mouse mammary tumor virus (mmtv) that causes t-cell lymphomas in mice. we have constructed a tblv-mmtv hybrid, phyb-tblv, in which 756 bp of the c3h mmtv long terminal repeat (ltr) was replaced with 438 bp of the tblv ltr. intraperitoneal injection of phyb-tblv transfectants consistently resulted in t-cell lymphomas in 50% of injected weanling balb/c mice with an average latency period of 5.7 (+/- 1.5) months. transfectants of phyb-tblv containing ... | 2003 | 12610163 |
| muc1 alters beta-catenin-dependent tumor formation and promotes cellular invasion. | muc1 is aberrantly expressed in greater than 90% of all breast carcinomas, yet its function as a tumor antigen is not fully understood. recently, studies have shown that muc1 interacts with beta-catenin, erbb receptors, src, gsk-3beta and protein kinase cdelta, possibly in a complex that promotes the disassembly of adherens junctions and the invasion of cells. here we show that the deletion of muc1 expression from mmtv-wnt-1 transgenic mice results in a significant increase in the time to mammar ... | 2003 | 12618757 |
| mouse mammary tumor virus-like gene sequences in breast tumors of australian and vietnamese women. | there is considerable evidence that the presence of mouse mammary tumor virus (mmtv)-like gene sequences in human breast cancer is highly associated with human breast carcinoma. previous studies have found mmtv-like gene sequences in 38% of breast cancer tissue from united states women. the prevalence of these sequences in australian and vietnamese women has never been reported. | 2003 | 12631616 |
| cbp recruitment and histone acetylation in differential gene induction by glucocorticoids and progestins. | we have analyzed histone acetylation at the steroid-responsive mouse mammary tumor virus (mmtv) promoter in five separate cell lines that express functional glucocorticoid and/or progesterone receptors. chromatin immunoprecipitation assays reveal that glucocorticoid and progesterone receptors bind the mmtv promoter after hormone addition but that receptor binding is not associated with an increase in acetylation of histone h3 or h4. we have, however, found one exception to this rule. previously ... | 2003 | 12637584 |
| complex role of histone h1 in transactivation of mmtv promoter chromatin by progesterone receptor. | transcription from the mouse mammary tumor virus (mmtv) promoter can be induced by glucocorticoids or progestins. the corresponding receptors bind to a cluster of hormone responsive elements (hres) and activate the promoter by synergistic interactions with ubiquitous transcription factors, in particular nuclear factor 1 (nf1). synergism between hormone receptors and nf1 depends on the precise positioning of the promoter sequences on the surface of a histone octamer in chromatin, but how linker h ... | 2002 | 12650697 |
| quantitative characterization of specific genomic promoters using agarose gel electrophoresis. | over the past decade a large number of studies have focused attention on the role of nucleosomes as negative and positive regulators of specific nuclear functions. due to the lack of an analytical method to determine the higher order conformation of the nucleosomal arrays that encompass specific genetic loci (e.g., promoters, enhancers), research emphasis has mostly been centered on chromatin remodeling and histone posttranslational modifications. we have recently developed an agarose gel electr ... | 2003 | 12666180 |
| ephb4 receptor tyrosine kinase transgenic mice develop glomerulopathies reminiscent of aglomerular vascular shunts. | we have established transgenic mice over-expressing the ephb4 receptor tyrosine kinase in the kidney. the ephb4 protein was localised to the developing tubular system of both control and transgenic newborn mice. in transgenic adults, transgene expression persisted in the proximal tubules and the bowman's capsules, structures, which were not stained in control kidneys. the glomeruli of control animals consisted of regular, round vascular baskets with clearly discernable afferent and efferent arte ... | 2003 | 12676328 |
| prokaryotic and eukaryotic translational machineries respond differently to the frameshifting rna signal from plant or animal virus. | many mutational and structural analyses of the rna signals propose a hypothesis that programmed frameshifting occurs by a specific interaction between ribosome and frameshifting signals comprised of a shifty site and a downstream rna structure, in which the exact nature of the interaction has not yet been proven. to address this question, we analyzed the frameshifting sequence elements from animal or plant virus in yeast and escherichia coli. frameshifting efficiencies varied in yeast, but not i ... | 2003 | 12686425 |
| expression of constitutively activated akt in the mammary gland leads to excess lipid synthesis during pregnancy and lactation. | expression of constitutively activated akt in the mammary glands of transgenic mice results in a delay in post-lactational involution. we now report precocious lipid accumulation in the alveolar epithelium of mouse mammary tumor virus-myr-akt transgenic mice accompanied by a lactation defect that results in a 50% decrease in litter weight over the first 9 days of lactation. although ductal structures and alveolar units develop normally during pregnancy, cytoplasmic lipid droplets appeared precoc ... | 2003 | 12700340 |
| prevention of her-2/neu transgenic mammary carcinoma by tamoxifen plus interleukin 12. | fvb-neun (n#202) female mice transgenic for the her-2/neu protooncogene driven by the murine mammary tumor virus (mmtv) promoter develop mammary carcinomas with a progression from focal atypical hyperplasia to in situ carcinoma and to invasive carcinoma that closely resembles that of human neoplasia. here we report that the combination of tamoxifen plus interleukin 12 (il-12) results in a very effective prevention of mammary carcinogenesis, significantly higher than those obtained with either ta ... | 2003 | 12704673 |
| nucleosomal arrays can be salt-reconstituted on a single-copy mmtv promoter dna template: their properties differ in several ways from those of comparable 5s concatameric arrays. | subsaturated nucleosomal arrays were reconstituted on a single-copy mmtv promoter dna fragment by salt dialysis procedures and studied by atomic force microscopy. up to an occupation level of approximately eight nucleosomes on this 1900 bp template, salt reconstitution produces nucleosomal arrays which look very similar to comparably loaded 5s rdna nucleosomal arrays; i.e., nucleosomes are dispersed on the dna template. thus, at these occupation levels, the single-copy mmtv template forms arrays ... | 2003 | 12705831 |
| differential dna binding of ku antigen determines its involvement in dna replication. | ku antigen (ku70/ku80) is a regulatory subunit of dna-dependent protein kinase, which participates in the regulation of dna replication and gene transcription through specific dna sequences. in this study, we have compared the mechanism of action of ku from a3/4, a dna sequence that appears in mammalian origins of dna replication, and nre1, a transcriptional regulatory element in the long terminal repeat of mouse mammary tumor virus through which ku antigen and its associated kinase, dna-depende ... | 2003 | 12713733 |
| the septin 9 (msf) gene is amplified and overexpressed in mouse mammary gland adenocarcinomas and human breast cancer cell lines. | the expression of polyomavirus middle t antigen under the control of the mouse mammary tumor virus promoter in transgenic mice results in the induction of aggressive mammary gland adenocarcinomas at an early age. we screened 26 tumors for chromosomal aneuploidies using sky and cgh. in 70% of the tumor samples we could detect high-level copy number gains, which mapped to chromosome band 11e2, a region orthologous to human 17q25.3. we then identified a bacterial artificial chromosome clone that la ... | 2003 | 12727837 |
| subversion of the innate immune system by a retrovirus. | retroviruses evolve rapidly to avoid the immune response of the infected host. we show here that the wild-type mouse mammary tumor virus mmtv(c3h) persisted indefinitely in c3h/hen mice. however, it was rapidly lost in mice of the closely related c3h/hej strain and was replaced by a virus recombinant with an endogenous mtv provirus. maintenance of the wild-type virus was dependent on toll-like receptor-4 (tlr4) signaling, which triggered production of the immunosuppressive cytokine interleukin-1 ... | 2003 | 12730691 |
| effect of moderate caloric restriction and/or weight cycling on mammary tumor incidence and latency in mmtv-neu female mice. | recently, we reported that intermittent caloric restriction-refeeding reduces mammary tumor (mt) incidence and extends latency in murine mammary tumor virus (mmtv)-transforming growth factor (tgf)-a mice to a greater extent than does chronic caloric restriction. here, this same weight-cycling protocol was applied to mmtv-neu female mice, which develop mts at a much younger age than do tgf-a mice. this study consisted of three experimental groups: mice fed an ain-93m diet ad libitum, mice intermi ... | 2002 | 12734063 |
| development of a high-performance reporter plasmid for detection of chemicals with androgenic activity. | a number of chemicals are present in the environment, and some synthetic chemicals may disrupt endocrine function of wild animals and humans. an effective procedure to screen chemicals for endocrine modulating activity has been needed to ensure the safety of chemicals, and the reporter gene assay technique may provide a powerful tool for screening endocrine-disrupting chemicals. we have developed a high-performance reporter plasmid that can trigger high androgen-dependent induction with high sel ... | 2003 | 12734641 |
| transformation of rodent fibroblasts by the jaagsiekte sheep retrovirus envelope is receptor independent and does not require the surface domain. | jaagsiekte sheep retrovirus (jsrv) is the etiological agent of a contagious lung cancer of sheep known as ovine pulmonary adenocarcinoma (opa). expression of the jsrv envelope protein (env) is sufficient to transform immortalized and primary fibroblasts, but the precise mechanisms of this process are not known. the cellular receptor for jsrv is hyaluronidase 2 (hyal-2), the product of a putative tumor suppressor gene that in humans maps to a chromosomal region frequently deleted in the developme ... | 2003 | 12743291 |
| chromatin remodeling by nuclear receptors. | the eukaryotic genome is structurally organized into nucleosomes to form chromatin, which regulates gene expression, in part, by controlling the accessibility of regulatory factors. when packaged as chromatin, many promoters are transcriptionally repressed, thus reducing the access of transcription factors to their binding sites. however, nuclear receptors (nrs) are a group of transcription factors that have the ability to access their binding sites in this repressive chromatin structure. nuclea ... | 2003 | 12743713 |
| the fk506-binding immunophilin fkbp51 is transcriptionally regulated by progestin and attenuates progestin responsiveness. | fkbp51 and fkbp52 are large molecular weight fk506-binding immunophilins that have diverse biochemical functions. best studied is the role that they play as components of steroid hormone receptors. differential display and gene array screens have identified fkbp51 as a progestin-inducible gene. here we demonstrate progestin enhancement of fkbp51 mrna and protein in t-47d cells. fkbp51 mrna and protein levels were increased 3-fold by 20 nm r5020. induction of fkbp51 mrna was unaffected by 1 micro ... | 2003 | 12746298 |
| targeted expression of the dominant-negative prolactin receptor in the mammary gland of transgenic mice results in impaired lactation. | the f3-short form of the rat prl receptor (f3-sprlr) form acts as a dominant negative inhibitor in vitro. we have developed a transgenic mouse model in which the rat f3-sprlr was expressed in mammary epithelium under the control of the mouse mammary tumor virus promoter. two lines of mice were characterized and shown to express the transgene in the mammary gland. no developmental abnormalities or differences from wild-type littermates were observed on the basis of size, activity, or fertility. m ... | 2003 | 12746331 |
| progesterone and glucocorticoid receptors recruit distinct coactivator complexes and promote distinct patterns of local chromatin modification. | it is well established that steroid receptor function requires interaction with coactivators. however, the mechanisms through which steroid receptors elicit precise assembly of coactivator complexes and the way the steroid activation signal is transduced remain elusive. using a t47d cell line stably integrated with a mouse mammary tumor virus-chloramphenicol acetyltransferase (mmtv-cat) reporter, we demonstrate that specific steroid receptors exhibit preferential recruitment of src-1 family coac ... | 2003 | 12748280 |
| pyv-mt-induced parotid gland hyperplasia as detected by altered lectin reactivity is not modulated by inducible nitric oxide deficiency. | the parotid gland was one of the first organs recognised to be sensitive to the transforming effects of polyomavirus. this study examines parotid gland pathology in mice expressing the polyomavirus middle t (pyv-mt) under the control of the mouse mammary tumour virus long terminal repeat (mmtv-ltr) to (1) demonstrate the utility of this model for studying premalignant disease; (2) identify early lesions by lectin staining and (3) determine effects of the inducible nitric oxide synthase (inos) in ... | 2003 | 12749913 |
| myeloid cell expansion elicited by the progression of spontaneous mammary carcinomas in c-erbb-2 transgenic balb/c mice suppresses immune reactivity. | transgenic female mice expressing the transforming rat oncogene c-erbb-2 (her-2/neu) under the mouse mammary tumor virus (mmtv) promoter (balb-neut) spontaneously develop mammary carcinomas with a progression resembling that of human breast cancer. in these mice, activating antitumor immunotherapy fails to induce t cell-mediated cytotoxicity, suggesting a suppression of the immune response. we found a direct correlation between tumor multiplicity and an increased proportion of gr-1+ (ly6g)/mac-1 ... | 2003 | 12750171 |
| hormonal and dietary modulation of mammary carcinogenesis in mouse mammary tumor virus-c-erbb-2 transgenic mice. | exogenous and dietary estrogens have been associated with modification of breast cancer risk. mammary cancer model systems can be used to explore interactions between specific transgenes, and hormonal and dietary factors. transgenic mice bearing the rat wild-type erbb-2 gene were used to study the effects of short-term hormonal exposure [17beta-estradiol (e2) or tamoxifen] or a soy meal diet on mammary carcinogenesis. in mice fed a casein diet, mammary tumors developed at an earlier age after sh ... | 2003 | 12750262 |
| immunotherapy of spontaneous mammary carcinoma with fusions of dendritic cells and mucin 1-positive carcinoma cells. | the tumour-associated antigen mucin 1 (muc1) is a multifunctional protein involved in protection of mucous membranes, signal transduction, and modulation of the immune system. more than 70% of cancers overexpress muc1, making muc1 a potential target for immunotherapy. in the present study, muc1 transgenic mice were crossed with syngeneic strains that express the polyomavirus middle-t oncogene (pymt) driven by the mouse mammary tumour virus promoter long-terminal repeat (mmtv-ltr). the resultant ... | 2003 | 12757626 |
| interleukin-6 differentially regulates androgen receptor transactivation via pi3k-akt, stat3, and mapk, three distinct signal pathways in prostate cancer cells. | the effects of il-6 on prostate cancer cells are well documented yet remain controversial. some reports suggested that il-6 could promote prostate cancer cell growth, while others showed that il-6 could repress prostate cancer cell growth. here, we systemically examined various il-6 signaling pathways in prostate cancer cells and found that il-6 could go through at least three distinct pathways to modulate the functions of androgen receptor (ar), a key transcriptional factor to control the prost ... | 2003 | 12763015 |
| the mature reverse transcriptase molecules in virions of mouse mammary tumor virus possess protease-derived sequences. | our efforts to express in bacteria the enzymatically active reverse transcriptase (rt) of mouse mammary tumor virus (mmtv) have shown that the rt is active only after adding 27 amino acid residues, which are derived from the end of the pro gene, to the amino-terminus of the rt (biochem, j. (1998) 329, 579-587). in the present study we have tested whether the mature rt found in virions is also fused to protease-derived sequences. to this end, we have analyzed the rt molecules in virions of mmtv b ... | 2003 | 12788639 |
| the mouse mammary tumor virus-like env gene sequence is not detectable in breast cancer tissue of austrian patients. | the mammary mouse tumor virus (mmtv) has been related to human breast cancer in previous studies, but these have yielded contradictory results. an mmtv env gene-like sequence was detectable in a relatively high proportion (38%) of human breast cancer tissues. the aim of this study was to determine the proportion of this 660 bp mmtv env gene-like sequence in a population of austrian breast cancer patients. we performed pcr, repeat pcr, and nested pcr. we did not find any exogenous mmtv env gene s ... | 2003 | 12792764 |
| mmtv-related env sequences in human breast tumor. | | 2003 | 12794768 |
| transforming growth factor beta signaling impairs neu-induced mammary tumorigenesis while promoting pulmonary metastasis. | the influence of transforming growth factor beta (tgf-beta) signaling on neu-induced mammary tumorigenesis and metastasis was examined with transgenic mouse models. we generated mice expressing an activated tgf-beta type i receptor or dominant negative tgf-beta type ii receptor under control of the mouse mammary tumor virus promoter. when crossed with mice expressing activated forms of the neu receptor tyrosine kinase that selectively couple to the grb2 or shc signaling pathways the activated ty ... | 2003 | 12808151 |
| the role of ink4a/arf in erbb2 mammary gland tumorigenesis. | most human tumors display inactivation of the p53 and the p16(ink4)/prb pathway. the ink4a/alternative reading frame (arf) locus encodes the p16(ink4a) and p14(arf) (murine p19(arf)) proteins. p16(ink4a) is deleted in 40-60% of breast cancer cell lines, and p16(ink4a) inactivation by dna methylation occurs in < or =30% of human breast cancers. in mice genetically heterozygous for p16(ink4a) or ink4a/arf, predisposition to specific tumor types is enhanced. ink4a/arf(+/-) mice have increased e mic ... | 2003 | 12810676 |
| activation of beta-catenin in prostate epithelium induces hyperplasias and squamous transdifferentiation. | the wnt/beta-catenin signaling pathway is critical for normal mammalian development, the specification of epidermal cells and neoplastic transformation of intestinal epithelium. however, precise molecular information regarding cell-specific responses to beta-catenin signaling has been limited. this question was addressed using a mouse model in which exon 3 of the beta-catenin gene was deleted in several cell types with loxp-mediated recombination utilizing a cre transgene under control of the mo ... | 2003 | 12813461 |
| t cell receptor revision does not solely target recent thymic emigrants. | cd4(+)vbeta5(+) t cells enter one of two tolerance pathways after recognizing a peripherally expressed superantigen encoded by an endogenous retrovirus. one pathway leads to deletion, while the other, termed tcr revision, results in cellular rescue upon expression of an alternate tcr that no longer recognizes the tolerogen. tcr revision requires the rearrangement of novel tcr beta-chain genes and depends on recombinase-activating gene (rag) expression in peripheral t cells. in line with recent f ... | 2003 | 12817002 |