Properties of transformed hamster cells containing sv40 tumor antigen in the cytoplasm

Richardson, Linda S.; Butel, Janet S.

doi:10.1002/ijc.2910070109

Cited by 20 publications

(5 citation statements)

References 33 publications

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“…The earliest arising tumors appeared 134 and 206 days after inoculation with pBSV-1 and pBSVcT-3, respectively. These data are consistent with the weakly oncogenic nature of the parental PARA(2cT)-adenovirus 7 hybrid virus which induced only one tumor in 24 newborn hamsters (37).…”

Section: Resultssupporting

confidence: 84%

“…This implies that some cells, possibly of certain embryonic origin, are more permissive in their recognition of the sequence in T-ag required for nuclear transport, such that the mutated sequence in cT-ag is partially recognized. Previous studies have demonstrated that during extensive subculturing cells able to partially transport the mutant T-ag arise spontaneously from clonally derived transformed cells and from tumor lines that originally expressed only cytoplasmic T-ag (23,37). The critical physiological or biochemical difference between cells able to partially transport cT-ag and cells that do not remains to be elucidated.…”

Section: Discussionmentioning

confidence: 99%

“…The cT mutation does not inhibit the localization of T-ag on the cell surface (24). Initial investigations of the PARA(cT) mutant suggested that its transforming capacity relative to wild-type (WT) virus was dramatically reduced (10,23,32,37). Recently, the SV40 sequences from the PARA(cT) hybrid virus were used to construct an intact SV40 genome containing the cT mutation (25).…”

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confidence: 99%

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Differential ability of a T-antigen transport-defective mutant of simian virus 40 to transform primary and established rodent cells.

1985

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The transforming potential and oncogenicity of a simian virus 40 (SV40) mutant affecting T-antigen (T-ag), SV40(cT)-3, was examined in an effort to dissect T-ag functions in transformation. SV40(cT)-3 has a point mutation at nucleotide 4434 that abolishes the transport of T-ag to the nucleus but does not affect its association with the cell surface. Transfection-transformation assays were performed with primary cells and established cell lines of mouse and rat origin. The efficiency of transformation for established cell lines by SV40(cT)-3 was comparable to that of wild-type SV40, indicating that transformation of established cell lines can occur in the absence of detectable amounts of nuclear T-ag. Transformation of primary mouse embryo fibroblasts by SV40(cT)-3 was markedly influenced by culture conditions; the relative transforming frequency was dramatically reduced in assays involving focus formation in low serum concentrations or anchorage-independent growth. Immunofluorescence tests revealed that the transformed mouse embryo fibroblasts partially transport the mutant cT-ag to the cell nucleus. Transformed cell lines induced by SV40(cT)-3 did not differ in growth properties from wild-type transformants. SV40(cT)-3 was completely defective for the transformation of primary baby rat kidney cells, a primary cell type unable to transport the mutant T-ag to the nucleus. The intracellular localization of cellular protein p53 was found to mimic T-ag distribution in all the transformants analyzed. The mutant virus was weakly oncogenic in vivo: the induction of tumors in newborn hamsters by SV40(cT)-3 was reduced in incidence and delayed in appearance in comparison to wild-type SV40. These observations suggest that cellular transformation is regulated by both nuclear and surface-associated forms of SV40 T-ag.

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Section: Resultssupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Differential ability of a T-antigen transport-defective mutant of simian virus 40 to transform primary and established rodent cells.

1985

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“…b S (surface) antiserum was prepared by immunizing hamsters four times with mycoplasma-free PARA-transformed marmoset cells. Unfixed cells were stained by an indirect immunofluorescence technique described previously (25). The reaction of the S antiserum with SV40-transformed cells was not diminished by absorption with either sheep red blood cells or herpes simplex virus type 11-transformed hamster cells.…”

Section: Ha /A30mentioning

confidence: 99%

“…The hamster serum was followed by fluorescein-labeled antihamster baboon globulin. SV40 S antigen was detected by a method described previously (25). The S antibody was from hamsters immunized four times with PARA-adenovirus 7-transformed marmoset cells (S. S. Layne and F. Rapp, Bacteriol.…”

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confidence: 99%

Role of simian virus 40 gene A function in maintenance of transformation

Brugge¹,

Butel²

1975

J Virol

311

105

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Mouse, hamster, and human cells were transformed at the permissive temperature by mutants from simian virus 40 (SV40) complementation group A in order to ascertain the role of the gene A function in transformation. The following parameters of transformation were monitored with the transformed cells under permissive and nonpermissive conditions: morphology; saturation density; colony formation on plastic, on cell monolayers, and in soft agar; uptake of hexose; and the expression of SV40 tumor (T) and surface (S) antigens. Cells transformed by the temperature-sensitive (ts) mutants exhibited the phenotype of transformed cells at the nonrestrictive temperature for all of the parameters studied. However, when grown at the restrictive temperature, they were phenotypically similar to normal, untransformed cells. Growth curves showed that the ts A mutant-transformed cells exhibited the growth characteristics of wild-type virus-transformed cells at the permissive temperature and resembled normal cells when placed under restrictive conditions. There were 3to 51-fold reductions in the levels of saturation density, colony formation, and uptake of hexose when the mutant-transformed cells were grown at the elevated temperature as compared to when they were grown at the permissive temperature. Mutant-transformed cells from the nonpermissive temperature were able to produce transformed foci when shifted down to permissive conditions, indicating that the phenotypically reverted cells were still viable and that the reversion was a reversible event. SV40 T antigen was present in the cells at both temperatures, but S antigen was not detected in cells maintained at the nonpermissive temperature. All of the wild-type virus-transformed cells exhibited a transformed phenotype when grown under either restrictive or nonrestrictive conditions. These results indicate that the SV40 group A mutant-transformed cells are temperature sensitive for the maintenance of growth properties characteristic of transformation. Virus rescued from the mutant-transformed cells by the transfection method was ts, suggesting that the SV40 gene A function, rather than a cellular one, is responsible for the ts behavior of the cells. 619 on August 1, 2020 by guest http://jvi.asm.org/ Downloaded from 620

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Adenovirus—Simian Virus 40 Interactions

Klessig

1984

The Adenoviruses

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Properties of transformed hamster cells containing sv40 tumor antigen in the cytoplasm

Abstract: The properties of hamster cells containing SV40 tumor ( T )

Cited by 20 publications

References 33 publications

Differential ability of a T-antigen transport-defective mutant of simian virus 40 to transform primary and established rodent cells.

Differential ability of a T-antigen transport-defective mutant of simian virus 40 to transform primary and established rodent cells.

Role of simian virus 40 gene A function in maintenance of transformation

Adenovirus—Simian Virus 40 Interactions

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