All classes of vertebrates harbor tumor viruses that are capable of inducing either tumors or leukemias. After infection, their genomes become integral parts of the host cell's genetic material (DNA). Many biological functions such as the capacity to code for the synthesis of new proteins and, in particular, the oncogenic property (oncogen) have already been assigned to specific regions (on physical maps) of their DNA.

Die Molekularbiologie der Tumorviren

The polypeptides of adenovirus: I. Evidence for multiple protein components in the virion and a comparison of types 2, 7A, and 12☆

Trans-membrane control of the receptors on normal and tumor cells. II. Surface changes associated with transformation and malignancy.

1 Separation of Tumor Cells from Fibroblasts.- 2 Development of Media for Isolation and Cultivation of Human Cancer Cells.- 3 New Approaches to the Cultivation of Human Breast Carcinomas.- 4 Old and New Problems in Human Tumor Cell Cultivation.- 5 New Human Tumor Cell Lines.- 6 Human Brain Tumor Cells in Matrix Culture.- 7 Neoplastic Human Glia Cells in Culture.- 8 Current Research with Organ Cultures of Human Tumors.- 9 Metabolic Gradients in Tissue Culture Studies of Human Cancer Cells.- 10 Human Lung Cancer in Tissue Culture.- 11 Cell Lines from Humans with Hematopoietic Malignancies.- 12 Cytological Characterization of Human Tumor Cells from Monolayer Cultures.- 13 Chromosome Abnormalities in Human Tumor Cells in Culture.- 14 Ultrastructural Characteristics of Human Tumor Cells in Vitro.- 15 The Strategy of a Search for Viral Involvement in Human Cancer.- 16 Helper Activity for the Defective Friend Leukemia Virus in Human Malignant Cell Cultures.

Human tumor cells in vitro

Transport of sugars in tumor cell membranes

Publisher Summary This chapter reviews the structure, function, and immunological properties of C-type virus-directed macromolecules that are immunologically active, and therefore approachable by immunological techniques. Antigen is used to designate such molecules, essentially because the chemical constitution of many of them is not yet known. The mechanism of virus assembly by a budding process suggests that the virus may contain many host cell constituents that are not essential to the virus structure, but rather represent virus-associated “contaminant.” It also seems feasible that as a result of virus-induced changes in cell physiology new antigenic determinants appear either by the exposure of hidden antigenic macromolecules or through the synthesis of new antigens as a result of the derepression of cellular genes that are inactive in a normal cell. The chapter focuses on C-type viruses of different species, which are closely related with respect to fundamental properties. They mature by budding from the cell membrane, are similar in the morphology, size, and constitution of nucleic acid, proteins, lipids, and enzymes, and require similar cell growth conditions for infection.

Virion and Tumor Cell Antigens of C-Type RNA Tumor Viruses

Oncornavirus-like particles have been consistently observed over a period of 3 years in HeLa cells obtained from several laboratories. The particles mature by budding, in that previously fully assembled A-type-like particles are enveloped by the protruding cell membrane with subsequent release of the virion. When compared morphologically to B- and C-type particles, distinct differences were observed; however, the HeLa particles closely resemble two primate viruses, namely the Mason-Pfizer monkey virus and a recently discovered virus derived from human brain cells. HeLa particles demonstrate a narrow host range. Thus a new morphological group of viruses emerges that might be specific for primates.



Detection de Particules du Type Oncornavirus dans les Cellules HeLa I. Ultra Structure et Classification Morphologique Comparee



Des particules du type oncornavirus ont ete regulierement observees pendant deux ans dans des cellules HeLa fournies par plusieurs laboratoires. Les particules mǔrissent par bourgeonnement, c'est-a-dire que les particules qui semblent ětre du type A et qui etaient auparavant totalement assemblees sont enveloppees par des protuberances de la membrane cellulaire, puis des virions sont liberes. Lorsqu'on les compare aux particules de type B ou C sous l'angle morphologique, on observe de nettes differences; toutefois, les particules HeLa ressemblent fortement a deux virus de primates, le virus de singe Mason-Pfizer et un virus recemment decouvert qui provient des cellules de cerveau humain. Les particules HeLa ont une gamme limitee d'hǒtes. Un nouveau groupe morphologique de virus a donc ete decouvert; il est peut-ětre specifique des primates.

Detection of oncornavirus-like particles in HeLa cells. I. Fine structure and comparative morphological classification.

Common tumor-Specific surface antigens on cells of different species transformed by avian RNA tumor viruses

Avian oncornavirus-induced tumor antigens of embryonic and unknown origin.

IT is well established that cyclic adenosine 3′ : 5′-monophosphate (cyclicAMP) acts as an intracellular transmitter substance regulating many physiological processes1,2. It was found that the intracellular level of cyclicAMP in transformed and in rapidly growing normal cells is lower than in slowly dividing or stationary normal cells3,4. Addition of N6O2′-dibutyryl adenosine cyclic 3′ : 5′-monophosphoric acid (dbcyclicAMP) to the medium of cultured cells increases the intracellular levels of cyclicAMP5 and has a normalizing effect on tumour cells6–11. This effect is potentiated by theophylline (Th). Both substances are inhibitors of intracellular cyclic nucleotide phosphodiesterase12. As a most striking feature, tumour cell morphology is reverted and cells become less agglutinable by wheat germ agglutinin6,7. Also, transformed cells are restored to controlled growth as they grow to lower saturation density and apparently become contact inhibited during treatment with dbcyclicAMP plus Th6–8,13.

Heinz Bauer

Papers

Virion and Tumor Cell Antigens of C-Type RNA Tumor Viruses

Detection of oncornavirus-like particles in HeLa cells. I. Fine structure and comparative morphological classification.

Common tumor-Specific surface antigens on cells of different species transformed by avian RNA tumor viruses

Avian oncornavirus-induced tumor antigens of embryonic and unknown origin.

Influence of dibutyryl cyclicAMP and theophylline on cell surface antigens on oncornavirus transformed cells.