Tumors polyoma

Anionic polyelectrolytes have been shown to enhance resistance to bacteria and fungi, enhance immune response, inhibit adjuvent arthritis and either depress or stimulate phagocytic activity of the reticuloendothelial system [458,459]. Carboxylic acid polymers have shown interferon induction, antiviral activity, and tumor growth inhibition [460]. The effects include inhibition of sarcoma, leukemia, polyoma and vesicular stomatitis virus. In one application, the cytotoxicity of bleomycin toward cultured mammalian cells was synergisti-cally enhanced by stirring in the presence of high molecular weight polyfacrylic acid) [461]. 

DNA viruses that can trigger tumors are found in the classes of the polyomaviruses, the adenoviruses and the papUloma viruses. The polyoma viruses with the SV40 virus as a well studied representative, adenoma virus and human papUloma virus (HPV) are associated with formation of tumors in humans and have genes coding for proteins with the properties of oncoproteins. The oncoproteins of aU three viruses interfere with the pRb function by Ufting its inhibition of transcription factor E2F. It is assumed that the tumor-promoting activity of the proteins is due, in particular, to this property. 

A polyoma is a tumor or cancer that may grow in various organs of the body, such as the heart and the liver. Recently a substance has been isolated from polyomas of mice and hamsters that seems to be the causative agent of these tumors in both species. It is called the polyoma virus. Much knowledge has been gathered about its molecular structure. 

Another virus specific for sialic acid is murine polyoma virus. Two types of strains are known that differ in their specificity for sialic acid oligosaccharides those that form large plaques bind to oligosaccharides terminating in NeuAc(a2-3)Gal, whereas the small plaque strains also tolerate branched structures with a second, a2-6 linked, sialic acid, e.g. NeuAc(a2-3)Gaip3[NeuAc(a2-6)]GalNAc. These strains also differ in their ability to form tumors in mice - the small plaque strains produee few, if any, tumors, while... 

Tmns ienic model of breast cancer. FVB mice transgenic for the polyoma virus middle T (PyVT or PyMT) oncogene under the mouse mammary tumor virus (MMTV) long terminal repeat 206 (LTR), generated as previously described (IS)., are used for in vivo invasion assays at 12-14 weeks of age when the tumors are about 2 cm in diameter see Note 2). 

Dabrosin, C., Pahner, K., Muller, W.J., and Gauldie, J., Estradiol promotes growth and angiogenesis in polyoma middle T transgenic mouse mammary tumor explants. Breast Cancer... 

Bautch, V.L., Toda, S., Hassell, J.A., and Hanahan, D., Endothelial cell tumors develop in transgenic mice carrying polyoma virus middle T oncogene. Cell, 51, 529-537, 1987. 

Viral oncoproteins generated by certain adeno-, papilloma-, and polyoma viruses by physical attachment of virally encoded proteins to the retinoblastoma gene product tumor suppressor protein mark that protein for degradation by ubiquiti-nation. Those cells rendered defenseless due to the loss of the rb tumor suppressor gene or its protein RB, succumb to malignant transformation driven by an... 

Ascorbate and Cyclic Nucleotides. Many biological activities are potentiated by hormonal actions that utilize cyclic 3 5 -AMP and cyclic 3 5 -GMP as "second messengers." Lewin (195) has reviewed extensive evidence showing that ascorbate potentiates the formation of cyclic 3 5 -AMP and is concerned in the inhibition of processes that reduce the concentration of both cyclic 3 5 -AMP and cyclic 3 5 -GMP by hydrolyzing them to 5 -AMP and 5 -GMP, respectively. The role of these cyclic nucleotides in cancer is uncertain, but diminished adenyl cyclase activity has been noted in polyoma virus-transformed cells (45), and cyclic 3 5 -AMP has been shown to inhibit cell multiplication in vitro (195) and tumor growth in vivo (130). 

Papillomarirus (wart viruses, genital condylomas, and DNA tumor viruses). Polyomavirus (human polyoma-like viruses, SV-40). 

Yee KO, Connolly CM, Pines M, Lawler J (2006) Halofuginone inhibits tumor growth in the polyoma middle T antigen mouse via a thrombospondin-1 independent mechanism. Cancer Biol Ther 5(2) 218-224. doi 2419 [pii]... 

Hays, E.F. 1964. Comparative oncogenic properties of deoxyribonucleic acid from primary parotid gland tumors, passage parotid gland tumors, and polyoma virus. Cancer Res. 24 1741-1744. 

Vandeputte, M., H. Eyssen, H. Sobis, and P. DeSomer. 1974. Induction of polyoma tumors in athymic nude mice. Int. J. Cancer 14 445-450. 

With the recognition that certain antibodies can protect tumor cells against the host s immune response thereby resulting in tumor enhancement, therapy with unblocking antibodies has been attempted. Bansal and Sjogren96 studied a rat polyoma tumor system and found unblocking activity... 

Following the early observation of Klenk and Yamakawa and their associates, the presence of sialic acid residues at the surface of numerous cells was established, either by action of neuraminidase followed by determination of the cell electrophoretic mobility or by determination of the sialic acid released. For example, sialic acid residues were detected at the surface of EMich ascites tumor cells (Wallach and Eylar, 1961 Cook et aL, 1962), hamster kidney fibroblasts transformed by polyoma virus (Forrester et aL, 1964), squamous epithelial cells (Berwick and Coman, 1962), solid and ascites sarcoma cells (Cook et aL, 1963 Wallach and de Perez Esandi, 1964), normal and malignant rat liver cells (Kalant et aL, 1964), cells from human bronchial carcinoma, cells from rat myeloma, HeLa cells, and L-strain mouse fibroblasts (Fuhrmann etaL, 1962). 

Viral Action at the Level of Translation. It is known that in eukaryotic cells induction and repression of enzyme synthesis can occur at the level of messenger RNA (Tomkins and Martin, 1970). Thus, the SV40, polyoma, and Moloney sarcoma viruses could contain the genetic information for a common repressor molecule which could interfere with the synthesis of aminosugar transferase. Both DNA viruses can code for 5-10 polypeptides (Eckhart, 1969), and the potential coding capacity of the large RNA tumor viruses is extensive. 

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