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The use of molecular hybridization to track the mode of transmission and distribution of murine mammary tumor viruses: a model for etiologic studies of human breast cancer.
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Immunologic study of antigens and molecular hybridization of nucleic acids from milk of breast cancer patients.
Comparative study has shown that by the gel diffusion assay both anti-HEp-2 virus serum and anti-breast cancer milk ultrasediment serum precipitated an identical antigen in human milk specimens, which was not identical with the group specific antigen of the HEp-2 virus. At the same time tha anti-breast cancer milk serum did not precipitate the HEp-2 virus. However, molecular hybridization experiments revealed nucleotide sequences homologous to nucleic acids of oncornavirus of D-type in milk obtained from breast carcinoma patients as well as in milk of healthy donors.
Tumorigenicity and the quantity of virus DNA in polyoma-transformed and revertant cell lines.
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Differential distribution of mouse mammary tumor virus-related sequences in the DNA's of rats.
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Analysis of human cancer DNA for DNA sequences of human adenovirus type 4.
We investigated whether human adenovirus type 4 (Ad4) might cause cancer in humans. Cell culture and animal model studies indicated that Ad4-induced human tumors should contain Ad4 DNA sequences. Thus Ad4 DNA was labeled in vitro (sp act, approximately 10(7) 3H counts/min/microgram) and hybridized in liquid phase with DNA extracted from human tumors. No viral sequences were detected in 31 squamous cell carcinomas of the lung, 5 adenocarcinomas of the lung, 4 oat cell carcinomas of the lung, 4 carcinomas of the stomach, 10 carcinomas of the colon, 3 carcinomas of the kidney, 3 carcinomas of the breast, 2 carcinomas of the ovary, and 6 Hodgkin's lymphomas. Reconstruction experiments with added Ad4 DNA indicated that the probe detected about 1 copy of 5% of the Ad4 genome per tumor cell. Therefore, these data were strong evidence (but did not prove) that none of these particular tumors were induced by Ad4.
Oncornaviruses type D and their possible role in neoplastic processes.
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RNA tumor viruses and leukemia: evaluation of present results supporting their presence in human leukemias.
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Satellite DNA sequence content of polylysine-titratable and nuclease-resistant fractions of mouse liver hepatoma chromatin.
Micrococcal nuclease digestion of mouse TLT liver hepatoma chromatin proceeds rapidly to the point where approximately 35% of the DNA is recoverable by centrifugation of the chromatin DNA through 3M CsCl. The satellite DNA sequence content of this recoverable DNA is the same as whole chromatin DNA (10%). The 11s (penultimate digestion product) monomer, as well as intermediate multiples and relatively undigested large chromatin segments are separable on steep hlycerol gradients. The DNA isolated from these fractions also contains the normal 10% satellite DNA content. Progressive polylysine titration of chromatin followed by nuclease digestion gives anomalous recoveries of DNA but, nonetheless, the satellite sequence content titration of chromatin, followed by pronase and then nuclease digestion, again gave recoverable DNA with a satellite sequence content of 10%. These results are discussed in terms of the conclusion that nucleosome (or upsilon-body) structures are distributed in a random fashion over the genome.
The transforming gene of avian tumor viruses.
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Investigations on supercoiled DNA in various rat cells.
The effect of radiation induced single-strand breaks in nuclear DNA and the repair of this damages on the sedimentation properties of nucleoids obtained from rat spleen, rat thymus and rat Yoshida tumour cells was studied. A dose dependent effect of ethidium bromide intercalation on the behaviour of supercoiled DNA could be demonstrated. The repair process of radiation induced single-strand breaks in the DNA of Yoshida tumour cells was delayed in the presence of prostaglandin E2 in the incubation medium. Additionally some in vivo repair experiments were carried out on cells of whole body irradiated rats.
Occurrence of BK virus DNA in DNA obtained from certain human tumors.
DNA sequences from BK virus have been detected by measurements of reassociation kinetics in DNA preparations isolated from five of 12 human tumor tissues and three of four human tumor cell lines; no DNA sequences from BK virus could be found using the same assay in DNA samples obtained from nontumor tissues removed from various patients. Whether or not this association is trivial, indicative of infection by BK virus, or correlative with the tumor state must await the testing of additional samples of normal and tumor tissues as well as a definition of the physical state of the genome of BK virus.
Involvement of mouse mammary tumor virus in spontaneous and hormone-induced mammary tumors in low-mammary-tumor mouse strains.
The involvement of the mouse mammary tumor virus (MTV) in spontaneous and hormone-induced mammary tumors in low-mammary-tumor mouse strains was studied by comparing the amounts of MTV RNA and MTV DNA sequences in mammary tumors and other tissues of mice with an without hormonal treatments. The following results were obtained. (i) Mammary tumors which appeared in C3H mice as a result of an infection with MTV contained more MTV DNA compared with noninfected organs; these mammary tumors also contained more MTV RNA than was present in lactating mammary gland cells. (ii) Hormonal stimulation by administration of excessive amounts of prolactin via hypophyseal isografts in C3Hf and O20 mice resulted in an increased expression of MTV RNA in the mammary glands. This elevated level of MTV RNA expression was, however, not maintained in the hormone-induced mammary tumors. (iii) Spontaneous mammary tumors in BALB/c mice contained similar levels of MTV DNA and MTV RNA sequences as were found in other cells of these animals.
Hybridization of bovine papilloma virus type 1 and type 2 DNA to DNA from virus-induced hamster tumors and naturally occurring equine tumors.
DNAs from bovine papilloma virus(BPV)-induced hamster tumors and from equine connective tissue tumors of unknown etiology were examined for BPV DNA sequences by molecular hybridization. DNA from two distinct classes of BPV (type 1 and type 2) was labeled in vitro and used as probes. Analysis of DNA-DNA reassociation kinetics indicated that both virus types were capable of tumor induction in the hamster. DNA isolated from 6 of 7 equine tumors accelerated the reassociation of the BPV DNA probes. BPV type 1 or type 2 DNA hybridized extensively to DNA from 3 tumors, while 3 other tumors contained DNA sequences to which only a portion of the probes hybridized. Partial hybridization of probe DNAs to tumor DNA suggested the possible existence of a third BPV class.
Analysis of human cancer DNA's for DNA sequence of human adenovirus serotypes 3, 7, 11, 14, 16, and 21 in group B1.
We have investigated whether Group B human adenoviruses (Ad) (Ad3, Ad7, Ad11, Ad14, Ad16, and Ad21), which are widespread in the human population and are tumorigenic in hamsters, may play a role in human cancer. Hybridization of Ad7-radiolabeled DNA with DNA's from an Ad7-induced primary hamster tumor and from two cell lines (5728 and Ad7 P-cell) established from Ad7-induced hamster tumors indicated multiple copies per cell of 17, 30 to 36, and 20%, respectively of the Ad7 genome. Thus, cells transformed by Group B Ads resemble cells transformed by Group C and Group A Ad's in that they retain multiple copies of a variable fraction of the viral genome. These model studies suggest that possible Group B Ad-induced human cancer cells should contain one or more copies of virus DNA per cell. Therefore, we assayed human cancer DNA's for Ad sequences, by highly sensitive "saturation-hybridization" reactions with Ad7 or Ad11 DNA (4 X 10(6) to 2.1 x 10(8) cpm/microgram). We concentrated on cancers of the respiratory and digestive systems, because these systems are the most common sites of infection by Group B Ad's. In 8 independent experiments, no Ad7 sequences were detected in DNA's from 16 normal lung tissues, 18 normal tissues of the digestive system, 34 cancers of the respiratory system, 19 cancers of the digestive system, 11 cancers of the urinary system, 5 cancers of the genital system, 3 cancers of the breast, and 6 Hodgkin's lymphomas. Reconstruction controls with added Ad7 DNA indicated that about 0.05 to 0.1 copy of Ad7 DNA per cell should be detected. Ad11 is strongly implicated as a cause of acute hemorrhagic cystitis. In two independent experiments, no Ad11 sequences were detected in DNA's from 9 carcinomas of bladder, 10 carcinomas of prostate, 24 carcinomas of kidney, 3 hypernephromas, 3 Wilms' tumors, or 2 normal kidneys. Reconstruction experiments indicated that the cancer DNA assays had a sensitivity of 0.05 to 0.1 copy of Ad11 DNA per cell. The DNA's of Group B Ad's are greater than 85% homologous by hybridization; thus, these results are applicable to all Group B serotypes. Our data provide evidence (but not formal proof) that none of the human cancers that we analyzed were induced by Group B Ad's. These tumors represent about 50% of the tumors that affect humans. The possible involvement of Group B Ad's in other less common forms of human cancers is under investigation in our laboratory.
Cell cycle dependence for activation of Epstein-Barr virus by inhibitors of protein synthesis or medium deficient in arginine.
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Characterization of mouse ribosomal gene fragments purified by molecular cloning.
Four mouse ribosomal gene fragments cloned in lambda gtWES were studied by restriction enzyme mapping and Southern transfer experiments. These fragments were found to contain 18S DNA and transcribed as well as non-transcribed spacer DNA. Variation in the structure of these mouse DNA inserts was limited to one region of spacer DNA. This variation may reflect real structural differences found in mouse ribosomal genes or possibly deletion events which occurred during cloning. The transcribed regions of the inserts appear identical to one antoher and restriction enzyme fragments from this region correspond to fragments observed in digests of total mouse DNA. These clones will be useful in studying the structure of transcribed spacer DNA including the ribosomal gene promoter.