Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The distribution, antibody-induced redistribution, and shedding of murine mammary tumor virus (MuMTV) antigens and the surfaces of GR mouse ascites leukemia (GRSL) cells were studied by the immunoferritin technique and compared with the same activities of thy 1.2 and H-2.8 antigens. MuMTV antigens were redistributed easily and then largely shed from the cell surface; in contrast, H-2.8 antigen moved easily and probably was partially released from the plasms membrane and Thy 1.2 antigen moved slowly and was some what interiorized. The complement-dependent cytotoxicity test was used to study the possibility of antigenic modulation for these cell-surface antigens from the surface of the GRSL cells could be modulated by preincubation with anti-MuMTV serum, in contrast to H-2.8 and Thy 1.2 antigens. The results obtained with the immunoferritin technique and the cytotoxicity test correlated well and sug-ested that the shedding of MuMTV antigens from the cell surfaces may occur in vivo, providing the tumor a way to escape from the immune defense of the host. Thy 1.2 and H-2.8 antigens were present on the envolope of B and C particles, which suggested that these viruses do not select a Thy 1.2 or H-2.8-negative area of the GRSL cell surface as amaturation site.
 ...
PMID:Antibody-induced modulation and shedding of mammary tumor virus antigens on the surfaces of GR ascites leukemia cells as compared with normal antigens. 18 12

Steroid hormones have been demonstrated to induce in tissue culture the production of mouse mammary tumor viral (MMTV) RNA, proteins, and particles 10-fold compared with constitutive levels. However, previous data of increased viral RNA levels did not distinguish between an increased rate of viral-specific RNA synthesis and a slower rate of viral RNA degradation. According to the recently developed assay of Coffin et al. (1974) for measuring rates of viral RNA synthesis, short-term labeling experiments of a mouse mammary tumor cell line indicate that the glucocorticoid hormone dexamethasone stimulates a 3-fold increase in the synthesis of MMTV-specific RNA within 10 min after the addition of hormone and that stimulation of RNA synthesis reaches 5- to 10-fold within 30 to 60 min, while the synthesis of Moloney leukemia virus-specific RNA in the same cell is unaffected by steroids. The decay rates of pulse-labeled and accumulated MMTV RNA in the presence or absence of dexamethasone show this RNA to have a half-life of greater than 8 h. In addition, hormone-stimulated MMTV RNA appears to have an increased rate of decay compared to basal MMTV RNA, thus ruling out an increased stability of MMTV RNA in the presence of steroid hormones as the basis for increased RNA levels. Thus, the magnitude, rapidity, and specificity of hormone action on MMTV RNA synthesis indicate a primary effect upon transcription.
 ...
PMID:Steroid induction of mouse mammary tumor virus: effect upon synthesis and degradation of viral RNA. 18 61

Using a method for freeze-drying intact cells, uninfected and murine leukemia virus (MuLV)-infected JLSV9 cell surfaces, as well as murine mammary tumor virus (MuMTV)-infected cell surfaces, were examined by electron microscopy. The 10-nm knobs of MuLV and the 5-nm spikes of MuMTV were clearly revealed on the surfaces of budding viruses and were also found dispersed over the cell surface. The MuLV knobs are randomly arranged on the virus surface, whereas the MuMTV spikes are much more ordered. Because freeze-fractured budding viral envelopes are devoid of intramembranous particles, the observed surface particles do not appear to be merely accentuated intramembranous particles. This technique should permit further analysis of the morphogenesis of viral envelopes without the need for externally applied labels.
 ...
PMID:Application of freeze-drying intact cells to studies of murine oncornavirus morphogenesis. 18 70

Murine mammary tumor virus (MuMTV), produced from a glucocorticoid-stimulated C3H mouse mammary adenocarcinoma cell line, was free of murine leukemia virus and oncogenic for weanling BALB/c mice. Adenocarcinomas were induced by MuMTV as early as 136 days post inoculation and with as low as 5 X 10(3) virus particles/mouse. Tumor incidence did not correlate directly with virus dose; rather, it was low at higher MuMTV concentrations (1.2 X 10(8) particles/mouse), reached and optimum at 1.3 X 10(5) particles/mouse, and decreased with virus dilution.
 ...
PMID:Oncogenicity of murine mammary tumor virus produced in tissue culture: brief communication. 20 21

An antigen immunologically related to a group-specific antigen (gp52, a 52,000-dalton glycoprotein) of the mouse mammary tumor virus has been identified in paraffin sections of human breast cancers by means of the indirect immunoperoxidase technique. The specificity of the reaction with antibody against mouse mammary tumor virus was examined by absorption of the IgG with the following: (a) purified gp52; (b) a number of virus preparations (mouse mammary tumor virus, Rauscher leukemia virus, simian sarcoma virus, baboon endogenous virus, and Mason-Pfizer monkey virus); (c) normal plasma, leukocytes, breast tissue, milk, actin, collagen, and hyaluronic acid, all of human origin; (d) sheep erythrocytes and mucin. Only mouse mammary tumor virus (from C(3)H or Paris RIII strains and grown in either murine or feline cells) and purified gp52 eliminated the immunohistochemical reaction in the human breast tumors. Positive reactions were seen in 51 of 131 (39%) breast carcinomas of various histologic types, a minimal estimate in view of the limited number of sections from each tumor that could be examined. Negative reactions were obtained in all 119 benign breast lesions (cystic disease, fibroadenoma, papilloma, gynecomastia) and in all 18 normal breast tissues. With one exception, 99 carcinomas from 13 organs other than breast and 8 cystosarcomas were all negative.
 ...
PMID:Detection in human breast carcinomas of an antigen immunologically related to a group-specific antigen of mouse mammary tumor virus. 20 5

Simultaneous replication of murine mammary tumor virus (type B) and murine leukemia virus (type C) was demonstrated electron microscopically along continuous stretches of the plasma membrane of single cells in cultures ofthe Mm5mt/c1 cell line. Types B and C virus buds were discriminated in thin sections with the aid of a tannic acid fixative that revealed the type B surface spikes as a homogeneous band of intermediate density and constant width on the surfaces of some buds (type B), whereas others (type C) remained with relatively smooth envelopes. Both types B and C buds may contain morphologically identical horseshoe-shaped nucleoids. Therefore, their identify (type B or C) could be ascertained in thin sections only on the basis of recognition of surface spikes.
 ...
PMID:Type B and type C RNA tumor virus replication in single cells. Electron microscopy with tannic acid. 20 5

A complementary DNA (cDNA) probe to mouse mammary tumor virus (MMTV) RNA was synthesized using calf thymus DNA oligonucleotides as a random primer. This probe was then used to study the expression of MMTV RNA in cell lines from BALB/c tumors induced in vivo either spontaneously or in response to viral, chemical, or hormonal stimuli. The cDNA had a length of approximately 400 to 500 nucleotides and specifically hybridized to MMTV RNA and BALB/c lactating mammary gland RNA, but not to Moloney leukemia virus RNA. Calf thymus DNA-primed cDNA could protect 50% of iodinated MMTV RNA from S1 nuclease digestion at cDNA-RNA ratios of 1:1 and 90% of labeled viral RNA at ratios of 10:1. Thermal denaturation of MMTV RNA-cDNA hybrids yielded a T(m) of 88.5 degrees C, indicative of a well-base-paired duplex. Screening of mouse mammary tumor cells for MMTV sequences revealed that three out of five lines of BALB/c origin had undetectable levels of viral RNA (<three molecules per cell) by RNA excess hybridization. Two of the three "virus-negative" cell lines were derived from tumors induced by the chemical carcinogen 7,12-dimethylbenz(alpha)anthracene, whereas the third tumor occurred spontaneously. Two lines from tumors induced by either viral (mammary tumor virus) or hormonal (17-beta-estradiol) stimulus contained between three and nine molecules of MMTV RNA per cell by both RNA excess and cDNA excess hybridization. Clonal derivatives of these tumor lines had levels of viral RNA comparable to those of their parental lines. Therefore, it appears that the presence of detectable MMTV RNA sequences is not a necessary requirement for the maintenance of all murine mammary gland neoplasias.
 ...
PMID:Detection of mouse mammary tumor virus RNA in BALB/c tumor cell lines of nonviral etiologies. 21 78

Steady-state levels of murine mammary tumor virus (MuMTV) RNA were quantitated during mammary tumorigenesis in BALB/c mice by molecular hybridization with a representative MuMTV complementary DNA (cDNA) probe. Hyperplastic alveolar nodule (HAN) lines are preneoplastic mammary lesions that were induced in BALB/c mice by hormones alone or in combination with 7,12-dimethylbenz(a)anthracene and give rise to mammary tumors. The hormone-induced HAN lines D1 and D2 contained detectable amounts of hybridizable MuMTV sequences. MuMTV RNA sequences were also observed in five of the six transplanted BALB/c mammary tumors that were examined. Similar levels of hybridizable MuMTV RNA were observed between the D1 or D2 HAN line and mammary tumors derived from each HAN line. The D2 HAN line as well as D2, C4, and CD8 mammary tumors accumulated RNA that was apparently homologous to most of the MuMTV genome. Thermal denaturation of hybrids indicated extensive sequence homology between the MuMTV cDNA and hybridizable RNA in the BALB/c HAN lines and mammary tumors. A low level of type C viral RNA was observed in the BALB/c HAN lines and most mammary tumors by molecular hybridization with a cDNA to Moloney murine leukemia virus. These data demonstrate that MuMTV sequences are frequently expressed in hormone-induced BALB/c HAN lines and mammary tumors derived from HAN lines or ductal hyperplasias induced in BALB/c mice by hormones and/or a chemical carcinogen. The transition from the preneoplastic to the neoplastic state in BALB/c mice does not appear to be due to a change in the steady-state levels of MuMTV RNA since the hormone-induced HAN lines and mammary tumors had similar levels of hybridizable MuMTV RNA.
 ...
PMID:Murine mammary tumor virus expression during mammary tumorigenesis in BALB/c mice. 21 43

Methods for the purification of both murine mammary tumor (type B) and murine leukemia (type C) oncornaviral phosphoproteins are described, in which chromatography on alkyl-agarose derivatives is used as the primary fractionation step. Gel filtration or ion exchange chromatography on phosphocellulose was the only subsequent step required for the purification of the type B and type C viral proteins, respectively. The two-step protocols also resulted in the co-purification of a low molecular weight core protein from each virus. Recoveries of the viral proteins purified by this method, based on per cent contribution of individual polypeptides to total virion proteins, were 70% or greater. Radioimmunocompetition analysis of the purified murine mammary tumor virus major core protein as well as analysis of the RNA binding properties of purified low molecular weight type C virus proteins suggests that neither antigenic reactivity nor specific RNA binding characteristics are altered by the purification protocols. The availability of these procedures should aid studies on the possible function and immunochemical properties of the native murine oncornaviral phosphoproteins and may also be extended to the purification of other oncornaviral proteins.
 ...
PMID:Purification of murine oncornaviral phosphoproteins using alkyl agarose derivatives.. 22 Feb 61

Prostate tissues of a total of 61 normal mice from 10 different strains, including high (C3H/Dm, RIII/Dm, and A/Dm) and low (BALB/c/Dm, C3Hf/Bi/Dm, and C3Hf/He/TEX) mammary cancer, and high (AKR/Dm) and low (CBA/J/Cr, SJL/J/Cr, and C57/BL/6/TEX) leukemia strains were examined by electron microscopy for the presence of virus particles. These studies demonstrated that type-B virus particles were present in normal prostate tissues of some old mice from all the three high (C3H/Dm, RIII/Dm, and A/Dm) and one low (BALB/c/Dm) mammary cancer strains. They further demonstrated that varying number of type-C virus particles were present in prostate tissues of some young and old mice, including those from all the 10 strains, especially in a larger number in older mice, and that intracisternal type-A virus particles were observed in all the mice examined. Immunological characterization of type-B virus particles by fixed immunofluorescence tests and immunoelectron microscopy revealed that type-B virus particles in normal prostate tissues of old C3H/Dm and A/Dm mice are morphologically and immunologically similar to the mouse mammary tumor virus. Thus, prostate tissues of mice can be a potential source of horizontally transmitted mammary tumor virus in mice of at least some high mammary cancer strains.
 ...
PMID:Virus particles in normal prostate tissues of mice from ten strains, with special reference to type-B virus particles. 22 33


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>