scholarly journals The mdm-2 oncogene can overcome wild-type p53 suppression of transformed cell growth

1993 ◽  
Vol 13 (1) ◽  
pp. 301-306 ◽  
Author(s):  
C A Finlay
Keyword(s):  
P53 Protein ◽  
Mutant P53 ◽  
Wild Type ◽  
Rat Embryo ◽  
Ras Gene ◽  
Double Minute ◽  
Murine Double Minute ◽  
Low Levels ◽  
Wild Type P53 ◽  
P53 Genes

Expression of a p53-associated protein, Mdm-2 (murine double minute-2), can inhibit p53-mediated transactivation. In this study, overexpression of the Mdm-2 protein was found to result in the immortalization of primary rat embryo fibroblasts (REFs) and, in conjunction with an activated ras gene, in the transformation of REFs. The effect of wild-type p53 on the transforming properties of mdm-2 was determined by transfecting REFs with ras, mdm-2, and normal p53 genes. Transfection with ras plus mdm-2 plus wild-type p53 resulted in a 50% reduction in the number of transformed foci (relative to the level for ras plus mdm-2); however, more than half (9 of 17) of the cell lines derived from these foci expressed low levels of a murine p53 protein with the characteristics of a wild-type p53. These results are in contrast to previous studies which demonstrated that even minimal levels of wild-type p53 are not tolerated in cells transformed by ras plus myc, E1A, or mutant p53. The mdm-2 oncogene can overcome the previously demonstrated growth-suppressive properties of p53.

scholarly journals The mdm-2 oncogene can overcome wild-type p53 suppression of transformed cell growth.

1993 ◽  
Vol 13 (1) ◽  
pp. 301-306 ◽  
Author(s):  
C A Finlay
Keyword(s):  
P53 Protein ◽  
Mutant P53 ◽  
Wild Type ◽  
Rat Embryo ◽  
Ras Gene ◽  
Double Minute ◽  
Murine Double Minute ◽  
Low Levels ◽  
Wild Type P53 ◽  
P53 Genes

Expression of a p53-associated protein, Mdm-2 (murine double minute-2), can inhibit p53-mediated transactivation. In this study, overexpression of the Mdm-2 protein was found to result in the immortalization of primary rat embryo fibroblasts (REFs) and, in conjunction with an activated ras gene, in the transformation of REFs. The effect of wild-type p53 on the transforming properties of mdm-2 was determined by transfecting REFs with ras, mdm-2, and normal p53 genes. Transfection with ras plus mdm-2 plus wild-type p53 resulted in a 50% reduction in the number of transformed foci (relative to the level for ras plus mdm-2); however, more than half (9 of 17) of the cell lines derived from these foci expressed low levels of a murine p53 protein with the characteristics of a wild-type p53. These results are in contrast to previous studies which demonstrated that even minimal levels of wild-type p53 are not tolerated in cells transformed by ras plus myc, E1A, or mutant p53. The mdm-2 oncogene can overcome the previously demonstrated growth-suppressive properties of p53.

Human p53 and CDC2Hs genes combine to inhibit the proliferation of Saccharomyces cerevisiae

1992 ◽  
Vol 12 (3) ◽  
pp. 1357-1365
Author(s):  
J M Nigro ◽  
R Sikorski ◽  
S I Reed ◽  
B Vogelstein
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Inhibition ◽  
Mammalian Cells ◽  
P53 Protein ◽  
Inducible Promoter ◽  
Mutant P53 ◽  
Wild Type ◽  
Growth Inhibitory Activity ◽  
Wild Type P53 ◽  
P53 Genes

Human wild-type and mutant p53 genes were expressed under the control of a galactose-inducible promoter in Saccharomyces cerevisiae. The growth rate of the yeast was reduced in cells expressing wild-type p53, whereas cells transformed with mutant p53 genes derived from human tumors were less affected. Coexpression of the normal p53 protein with the human cell cycle-regulated protein kinase CDC2Hs resulted in much more pronounced growth inhibition that for p53 alone. Cells expressing p53 and CDC2Hs were partially arrested in G1, as determined by morphological analysis and flow cytometry. p53 was phosphorylated when expressed in the yeast, but differences in phosphorylation did not explain the growth inhibition attributable to coexpression of p53 and CDC2Hs. These results suggest that wild-type p53 has a growth-inhibitory activity in S. cerevisiae similar to that observed in mammalian cells and suggests that this yeast may provide a useful model for defining the pathways through which p53 acts.

scholarly journals Human p53 and CDC2Hs genes combine to inhibit the proliferation of Saccharomyces cerevisiae.

1992 ◽  
Vol 12 (3) ◽  
pp. 1357-1365 ◽  
Author(s):  
J M Nigro ◽  
R Sikorski ◽  
S I Reed ◽  
B Vogelstein
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Inhibition ◽  
Mammalian Cells ◽  
P53 Protein ◽  
Inducible Promoter ◽  
Mutant P53 ◽  
Wild Type ◽  
Growth Inhibitory Activity ◽  
Wild Type P53 ◽  
P53 Genes

Human wild-type and mutant p53 genes were expressed under the control of a galactose-inducible promoter in Saccharomyces cerevisiae. The growth rate of the yeast was reduced in cells expressing wild-type p53, whereas cells transformed with mutant p53 genes derived from human tumors were less affected. Coexpression of the normal p53 protein with the human cell cycle-regulated protein kinase CDC2Hs resulted in much more pronounced growth inhibition that for p53 alone. Cells expressing p53 and CDC2Hs were partially arrested in G1, as determined by morphological analysis and flow cytometry. p53 was phosphorylated when expressed in the yeast, but differences in phosphorylation did not explain the growth inhibition attributable to coexpression of p53 and CDC2Hs. These results suggest that wild-type p53 has a growth-inhibitory activity in S. cerevisiae similar to that observed in mammalian cells and suggests that this yeast may provide a useful model for defining the pathways through which p53 acts.

scholarly journals TRRAP is essential for regulating the accumulation of mutant and wild-type p53 in lymphoma

Blood ◽  
2018 ◽  
Vol 131 (25) ◽  
pp. 2789-2802 ◽  
Author(s):  
Alexander Jethwa ◽  
Mikołaj Słabicki ◽  
Jennifer Hüllein ◽  
Marius Jentzsch ◽  
Vineet Dalal ◽  
...  
Keyword(s):  
Protein Stability ◽  
P53 Protein ◽  
Mutant P53 ◽  
Wild Type ◽  
Therapeutic Targeting ◽  
Key Points ◽  
Wild Type P53

Key Points The HAT complex member TRRAP is vital for maintaining high p53 levels by shielding it against the natural p53 degradation machinery. Acetylation-modifying complexes regulate p53 protein stability, which may provide a basis for therapeutic targeting of mutant p53.

scholarly journals Co-expression of murine double minute 2 siRNA and wild-type p53 induces G1 cell cycle arrest in H1299 cells

2017 ◽  
Vol 16 (6) ◽  
pp. 9137-9142
Author(s):  
Long Liu ◽  
Ping Zhang ◽  
Hua Guo ◽  
Xinyu Tang ◽  
Lianqin Liu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Wild Type ◽  
Cycle Arrest ◽  
Double Minute ◽  
G1 Cell Cycle Arrest ◽  
Murine Double Minute ◽  
Wild Type P53

scholarly journals Mutant p53 tumor suppressor alleles release ras-induced cell cycle growth arrest.

1991 ◽  
Vol 11 (3) ◽  
pp. 1344-1352 ◽  
Author(s):  
G G Hicks ◽  
S E Egan ◽  
A H Greenberg ◽  
M Mowat
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Growth Regulation ◽  
Growth Arrest ◽  
Mutant P53 ◽  
Wild Type ◽  
Type Activity ◽  
Wild Type P53 ◽  
Negative Growth ◽  
P53 Genes

Overexpression of an activated ras gene in the rat embryo fibroblast line REF52 results in growth arrest at either the G1/S or G2/M boundary of the cell cycle. Both the DNA tumor virus proteins simian virus 40 large T antigen and adenovirus 5 E1a are able to rescue ras induced lethality and cooperate with ras to fully transform REF52 cells. In this report, we present evidence that the wild-type activity of the tumor suppressor gene p53 is involved in the negative growth regulation of this model system. p53 genes encoding either a p53Val-135 or p53Pro-193 mutation express a highly stable p53 protein with a conformation-dependent loss of wild-type activity and the ability to eliminate any endogenous wild-type p53 activity in a dominant negative manner. In cotransfection assays, these mutant p53 genes are able to rescue REF52 cells from ras-induced growth arrest, resulting in established cell lines which express elevated levels of the ras oncoprotein and show morphological transformation. Full transformation, as assayed by tumor formation in nude mice, is found only in the p53Pro-193-plus-ras transfectants. These cells express higher levels of the ras protein than do the p53Val-135-plus-ras-transfected cells. Transfection of REF52 cells with ras alone or a full-length genomic wild-type p53 plus ras results in growth arrest and lethality. Therefore, the selective event for p53 inactivation or loss during tumor progression may be to overcome a cell cycle restriction induced by oncogene overexpression (ras). These results suggest that a normal function of p53 may be to mediate negative growth regulation in response to ras or other proliferative inducing signals.

Wild-type p53 protein potentiates phototoxicity of 2-BA-2-DMHA in HT29 cells expressing endogenous mutant p53

1999 ◽  
Vol 138 (1-2) ◽  
pp. 189-195 ◽  
Author(s):  
Wen-Geng Zhang ◽  
Xiao-Wu Li ◽  
Li-Ping Ma ◽  
Shen-Wu Wang ◽  
Hong-Ying Yang ◽  
...  
Keyword(s):  
P53 Protein ◽  
Mutant P53 ◽  
Wild Type ◽  
Ht29 Cells ◽  
Wild Type P53

Mutant p53 tumor suppressor alleles release ras-induced cell cycle growth arrest

1991 ◽  
Vol 11 (3) ◽  
pp. 1344-1352
Author(s):  
G G Hicks ◽  
S E Egan ◽  
A H Greenberg ◽  
M Mowat
Keyword(s):  
Cell Cycle ◽  
Tumor Suppressor ◽  
Growth Regulation ◽  
Growth Arrest ◽  
Mutant P53 ◽  
Wild Type ◽  
Type Activity ◽  
Wild Type P53 ◽  
Negative Growth ◽  
P53 Genes

Overexpression of an activated ras gene in the rat embryo fibroblast line REF52 results in growth arrest at either the G1/S or G2/M boundary of the cell cycle. Both the DNA tumor virus proteins simian virus 40 large T antigen and adenovirus 5 E1a are able to rescue ras induced lethality and cooperate with ras to fully transform REF52 cells. In this report, we present evidence that the wild-type activity of the tumor suppressor gene p53 is involved in the negative growth regulation of this model system. p53 genes encoding either a p53Val-135 or p53Pro-193 mutation express a highly stable p53 protein with a conformation-dependent loss of wild-type activity and the ability to eliminate any endogenous wild-type p53 activity in a dominant negative manner. In cotransfection assays, these mutant p53 genes are able to rescue REF52 cells from ras-induced growth arrest, resulting in established cell lines which express elevated levels of the ras oncoprotein and show morphological transformation. Full transformation, as assayed by tumor formation in nude mice, is found only in the p53Pro-193-plus-ras transfectants. These cells express higher levels of the ras protein than do the p53Val-135-plus-ras-transfected cells. Transfection of REF52 cells with ras alone or a full-length genomic wild-type p53 plus ras results in growth arrest and lethality. Therefore, the selective event for p53 inactivation or loss during tumor progression may be to overcome a cell cycle restriction induced by oncogene overexpression (ras). These results suggest that a normal function of p53 may be to mediate negative growth regulation in response to ras or other proliferative inducing signals.

Nuclear accumulation of p53 protein is mediated by several nuclear localization signals and plays a role in tumorigenesis

1990 ◽  
Vol 10 (12) ◽  
pp. 6565-6577
Author(s):  
G Shaulsky ◽  
N Goldfinger ◽  
A Ben-Ze'ev ◽  
V Rotter
Keyword(s):  
Nuclear Localization ◽  
Cell Nucleus ◽  
P53 Protein ◽  
Simian Virus 40 ◽  
T Antigen ◽  
Nuclear Accumulation ◽  
Mutant P53 ◽  
Wild Type ◽  
Nuclear Localization Signals ◽  
Wild Type P53

The basic carboxy terminus of p53 plays an important role in directing the protein into the nuclear compartment. The C terminus of the p53 molecule contains a cluster of several nuclear localization signals (NLSs) that mediate the migration of the protein into the cell nucleus. NLSI, the most active domain, is highly conserved in genetically diverged species and shares perfect homology with consensus NLS sequences found in other nuclear proteins. The other two NLSs, II and III, appear to be less effective and less conserved. Although nuclear localization is dictated primarily by the NLSs inherent in the primary amino acid sequence, the actual nuclear homing can be modified by interactions with other proteins expressed in the cell. Comparison between wild-type p53 and naturally occurring mutant p53 showed that both protein categories could migrate into the nucleus of rat primary embryonic fibroblasts by essentially similar mechanisms. Nuclear localization of both proteins was totally dependent on the existence of functional NLS domains. In COS cells, however, we found that NLS-deprived wild-type p53 molecules could migrate into the nucleus by complexing with another nuclear protein, simian virus 40 large-T antigen. Wild-type and mutant p53 proteins differentially complexed with viral or cellular proteins, which may significantly affect the ultimate compartmentalization of p53 in the cell; this finding suggests that the actual subcellular compartmentalization of proteins may differ in various cell type milieux and may largely be affected by the ability of these proteins to complex with other proteins expressed in the cell. Experiments designed to test the physiological significance of p53 subcellular localization indicated that nuclear localization of mutant p53 is essential for this protein to enhance the process of malignant transformation of partially transformed cells, suggesting that p53 functions within the cell nucleus.

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