scholarly journals Hormonal regulation of the transformation phenotype in simian virus 40-transformed rat embryonic preadipose cell lines.

1984 ◽  
Vol 4 (4) ◽  
pp. 712-721 ◽  
Author(s):  
S Yasumoto
Keyword(s):  
Cell Density ◽  
Cell Lines ◽  
Hormonal Regulation ◽  
Growth Regulation ◽  
High Cell Density ◽  
Calf Serum ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
High Cell

The regulation of transformed phenotypes was studied in newly isolated preadipose cell lines which were established after infection with simian virus 40 tsA58 dl2009. The clonal cell lines isolated exhibited most of the characteristics typical of transformed cells. The transformants, however, were able to differentiate into adipocytes in the presence of low calf serum (0.5%) and a combination of several hormones, including hydrocortisone and insulin. Treatment with insulin alone stimulated the growth of these cells but did not induce lipid accumulation without added hydrocortisone. The effect of hydrocortisone was accompanied by a restoration of growth control in the transformants after they reached high cell density. The blot hybridization analysis of cellular DNAs digested by restriction enzymes revealed that simian virus 40 genomes were integrated at multiple separate sites at which a head-to-tail oligomeric insertion took place. Large T antigen was synthesized in growing cells but was regulated at high cell density when cells were committed to differentiate by glucocorticoids. These results suggest that the glucocorticoid hydrocortisone is capable of restoring growth regulation at high cell densities to simian virus 40-transformed preadipose cell lines.

Hormonal regulation of the transformation phenotype in simian virus 40-transformed rat embryonic preadipose cell lines

1984 ◽  
Vol 4 (4) ◽  
pp. 712-721
Author(s):  
S Yasumoto
Keyword(s):  
Cell Density ◽  
Cell Lines ◽  
Hormonal Regulation ◽  
Growth Regulation ◽  
High Cell Density ◽  
Calf Serum ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
High Cell

The regulation of transformed phenotypes was studied in newly isolated preadipose cell lines which were established after infection with simian virus 40 tsA58 dl2009. The clonal cell lines isolated exhibited most of the characteristics typical of transformed cells. The transformants, however, were able to differentiate into adipocytes in the presence of low calf serum (0.5%) and a combination of several hormones, including hydrocortisone and insulin. Treatment with insulin alone stimulated the growth of these cells but did not induce lipid accumulation without added hydrocortisone. The effect of hydrocortisone was accompanied by a restoration of growth control in the transformants after they reached high cell density. The blot hybridization analysis of cellular DNAs digested by restriction enzymes revealed that simian virus 40 genomes were integrated at multiple separate sites at which a head-to-tail oligomeric insertion took place. Large T antigen was synthesized in growing cells but was regulated at high cell density when cells were committed to differentiate by glucocorticoids. These results suggest that the glucocorticoid hydrocortisone is capable of restoring growth regulation at high cell densities to simian virus 40-transformed preadipose cell lines.

scholarly journals Rat embryo fibroblasts immortalized with simian virus 40 large T antigen undergo senescence upon its inactivation.

1996 ◽  
Vol 16 (9) ◽  
pp. 5127-5138 ◽  
Author(s):  
E S Gonos ◽  
J S Burns ◽  
G R Mazars ◽  
A Kobrna ◽  
T E Riley ◽  
...  
Keyword(s):  
Cell Lines ◽  
Fetal Calf Serum ◽  
Calf Serum ◽  
Growth Arrest ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Rat Embryo ◽  
G2 Block ◽  
Embryo Fibroblasts

Introduction of simian virus 40 T antigen into rodent fibroblasts gives rise to cells that can proliferate indefinitely but are dependent upon it for maintenance of their growth once the normal mitotic life span has elapsed. Inactivation of T antigen in these immortalized cells causes rapid and irreversible cessation of growth. To determine whether this growth arrest is associated with entry into senescence, we have undertaken a genetic and biological analysis of conditionally immortal (tsa) cell lines derived by immortalizing rat embryo fibroblasts with the thermolabile tsA58 T antigen. This analysis has identified the following parallels between the tsa cells after inactivation of T antigen and senescent rat embryo fibroblasts: (i) growth arrest is irreversible; (ii) it occurs in G1 as well as G2; (iii) the G1 block can be partially overcome by stimulation with 20% fetal calf serum, but the G2 block cannot be overcome; (iv) 20% fetal calf serum induces c-fos, but c-myc is unaltered; and (v) fibronectin and p21(Waf1/Cip1/Sdi1) are upregulated upon growth arrest. These results suggest that T-antigen-immortalized fibroblasts are committed to undergo senescence but are prevented from undergoing this process by T antigen. Inactivation of T antigen removes this block and results in senescence of the cells. Thus, these cell lines may represent a powerful system for study of the molecular basis of entry into senescence.

scholarly journals Systematic variables affecting simian virus 40-induced T-antigen expression and transformation in human cells

1976 ◽  
Vol 3 (6) ◽  
pp. 593-598
Author(s):  
M M Kaplan ◽  
A S Lubiniecki ◽  
W A Blattner ◽  
T Mason ◽  
D J Giard ◽  
...  
Keyword(s):  
Cell Density ◽  
Cell Lines ◽  
Simian Virus 40 ◽  
Antigen Expression ◽  
Simian Virus ◽  
T Antigen ◽  
General Effect ◽  
Initial Cell ◽  
Initial Cell Density ◽  
Risk Of Cancer

Simian virus 40 (SV40) infection of human skin fibroblast and human tumor cells resulted in the expression of T-antigen and transformed foci. By examining various conditions of input virus multiplicity and initial cell density, the systematic variation of T-antigen determination was minimized. The most uniform results were obtained at multiplicities of about 275 plaque-forming units/cell. Within limits (5 X 10(4) to 2 X 10(5) cells/dish), initial cell density had little effect on T-antigen expression. Volume of virus inoculum was critical for some cell lines, but not for others. Cell passage level had no general effect on T-antigen expression, although specific cell lines demonstrated increased or decreased levels of T-antigen expression with serial passage for no apparent reason. T-antigen expression correlated with virus-induced cell transformation (focus formation) at two different multiplicities. In addition, T-antigen assays at 3 days gave consistently more reproducible results than transformation assays at 21 days in seven cell lines tested at two multiplicities of infection. These results defined input multiplicity as the major source of systematic variability and will permit development of a more reproducible tool in the evaluation of individuals at high risk of cancer.

scholarly journals Analysis of a transgenic mouse containing simian virus 40 and v-myc sequences.

1985 ◽  
Vol 5 (4) ◽  
pp. 642-648 ◽  
Author(s):  
J A Small ◽  
D G Blair ◽  
S D Showalter ◽  
G A Scangos
Keyword(s):  
Cell Lines ◽  
Choroid Plexus Papilloma ◽  
Simian Virus 40 ◽  
Soft Agar ◽  
Simian Virus ◽  
T Antigen ◽  
Primary Cell ◽  
Tissue Samples ◽  
Primary Cell Lines

Two plasmids, one containing the simian virus 40 (SV40) genome and the mouse metallothionein I gene and one containing the v-myc gene of avian myelocytomatosis virus MC29, were coinjected into mouse embryos. Of the 13 surviving mice, one, designated M13, contained both myc and SV40 sequences. This mouse developed a cranial bulge identified as a choroid plexus papilloma at 13 weeks and was subsequently sacrificed; tissue samples were taken for further analysis. Primary cell lines derived from these tissues contained both myc and SV40 DNA. No v-myc mRNA could be detected, although SV40 mRNA was present in all of the cell lines tested. T antigen also was expressed in all of the cell lines analyzed. These data suggest that SV40 expression was involved in the abnormalities of mouse M13 and was responsible for the transformed phenotype of the primary cell lines. Primary cell lines from this mouse were atypical in that the population rapidly became progressively more transformed with time in culture based on the following criteria: morphology, growth rate, and the ability to grow in soft agar and in serum-free medium. The data also suggest that factors present in the mouse regulated the ability of SV40 to oncogenically transform most cells and that in vitro culture of cells allowed them to escape those factors.

Establishment of human cementifying fibroma cell lines by transfection with temperature-sensitive simian virus-40 T-antigen gene and hTERT gene

Bone ◽  
2002 ◽  
Vol 30 (5) ◽  
pp. 712-717 ◽  
Author(s):  
Y Kudo ◽  
M Hiraoka ◽  
S Kitagawa ◽  
M Miyauchi ◽  
S Kakuo ◽  
...  
Keyword(s):  
Cell Lines ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Temperature Sensitive ◽  
Htert Gene ◽  
Antigen Gene ◽  
Cementifying Fibroma

Recombinant retroviruses encoding simian virus 40 large T antigen and polyomavirus large and middle T antigens

1986 ◽  
Vol 6 (4) ◽  
pp. 1204-1217
Author(s):  
P S Jat ◽  
C L Cepko ◽  
R C Mulligan ◽  
P A Sharp
Keyword(s):  
Cell Lines ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Vector System ◽  
Large T Antigen ◽  
T Antigens ◽  
Sv40 Large T Antigen ◽  
Polyomavirus Middle T Antigen ◽  
Middle T Antigen

We used a murine retrovirus shuttle vector system to construct recombinants capable of constitutively expressing the simian virus 40 (SV40) large T antigen and the polyomavirus large and middle T antigens as well as resistance to G418. Subsequently, these recombinants were used to generate cell lines that produced defective helper-free retroviruses carrying each of the viral oncogenes. These recombinant retroviruses were used to analyze the role of the viral genes in transformation of rat F111 cells. Expression of the polyomavirus middle T antigen alone resulted in cell lines that were highly tumorigenic, whereas expression of the polyomavirus large T resulted in cell lines that were highly tumorigenic, whereas expression of the polyomavirus large T resulted in cell lines that were unaltered by the criteria of morphology, anchorage-independent growth, and tumorigenicity. More surprisingly, SV40 large T-expressing cell lines were not tumorigenic despite the fact that they contained elevated levels of cellular p53 and had a high plating efficiency in soft agar. These results suggest that the SV40 large T antigen is not an acute transforming gene like the polyomavirus middle T antigen but is similar to the establishment genes such as myc and adenovirus EIa.

scholarly journals Growth of immortal simian virus 40 tsA-transformed human fibroblasts is temperature dependent.

1989 ◽  
Vol 9 (7) ◽  
pp. 3093-3096 ◽  
Author(s):  
R L Radna ◽  
Y Caton ◽  
K K Jha ◽  
P Kaplan ◽  
G Li ◽  
...  
Keyword(s):  
Cell Lines ◽  
Human Fibroblasts ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Cellular Aging ◽  
Cellular Growth ◽  
Viral Gene ◽  
Large T Antigen ◽  
Temperature Dependent

Simian virus 40 (SV40)-mediated transformation of human fibroblasts offers an experimental system for studying both carcinogenesis and cellular aging, since such transformants show the typical features of altered cellular growth but still have a limited life span in culture and undergo senescence. We have previously demonstrated (D. S. Neufeld, S. Ripley, A. Henderson, and H. L. Ozer, Mol. Cell. Biol. 7:2794-2802, 1987) that transformants generated with origin-defective mutants of SV40 show an increased frequency of overcoming senescence and becoming immortal. To clarify further the role of large T antigen, we have generated immortalized transformants by using origin-defective mutants of SV40 encoding a heat-labile large T antigen (tsA58 transformants). At a temperature permissive for large-T-antigen function (35 degrees C), the cell line AR5 had properties resembling those of cell lines transformed with wild-type SV40. However, the AR5 cells were unable to proliferate or form colonies at temperatures restrictive for large-T-antigen function (39 degrees C), demonstrating a continuous need for large T antigen even in immortalized human fibroblasts. Such immortal temperature-dependent transformants should be useful cell lines for the identification of other cellular or viral gene products that induce cell proliferation in human cells.

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

1985 ◽  
Vol 5 (5) ◽  
pp. 1043-1050 ◽  
Author(s):  
R E Lanford ◽  
C Wong ◽  
J S Butel
Keyword(s):  
Cell Lines ◽  
Mouse Embryo ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Wild Type ◽  
Mouse Embryo Fibroblasts ◽  
Established Cell Lines ◽  
Established Cell ◽  
Embryo Fibroblasts

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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