Molecular analysis of different allelic variants of wild-type human p53

1992 ◽  
Vol 70 (10-11) ◽  
pp. 1014-1019 ◽  
Author(s):  
France Moreau ◽  
Greg Matlashewski
Keyword(s):  
Cultured Cells ◽  
Human Cancer ◽  
P53 Protein ◽  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Tumour Suppressor ◽  
Allelic Variant ◽  
Wild Type ◽  
Allelic Variants ◽  
Wild Type P53

The p53 tumour suppressor gene is intensively studied because mutations in this gene are the most common genetic alteration so far identified in human cancer. Considerable emphasis has thus been placed on characterizing the biological differences between mutant and wild-type p53 protein. This has led to the realization that in cultured cells, mutant p53 behaves like an oncogene, whereas wild-type p53 is a tumour suppressor gene. The p53 protein is also a target for the tumour virus oncogene products SV40 large T, adenovirus E1B, and human papillomavirus type 16 E6, which are all capable of forming complexes to the p53 protein. Although p53 represents an extremely important cellular regulatory molecule which is well conserved, there exists two allelic variants of wild-type human p53 that differ both in primary and confirmational structure. One variant contains an arginine at amino acid 72 (p53Arg), whereas the other form contains a proline at this residue (p53Pro). The possible implications for more than one allelic variant of wild-type human p53 in the general population is unknown. The present study was undertaken to compare some of the biological features of the different wild-type p53 variants. We present data demonstrating that there was a post-transcriptional selection against accumulation of both variants of wild-type human p53 in 3T3-A31 cells, arguing that both forms are proliferation inhibitory in these cells. Both variants of human p53 were stabilized by SV40 large T, but did not displace mouse p53 from SV40 large T. Neither allelic variant of human p53 was able to reduce significantly SV40-mediated anchorage-independent growth of 3T3-A31 cells. Taken together, these data suggest that although there are structurally different variants of wild-type human p53, there is no difference in the biological activity of these molecules at the level of the biological assays performed here.Key words: human p53, large T, transformation, oncogenes, tumour suppressor.

scholarly journals Characterising Mutational Spectra of Carcinogens in the Tumour Suppressor Gene TP53 Using Human TP53 Knock-in (Hupki) Mouse Embryo Fibroblasts

2019 ◽  
Vol 2 (4) ◽  
pp. 85 ◽  
Author(s):  
Hölzl-Armstrong ◽  
Kucab ◽  
Korenjak ◽  
Luijten ◽  
Phillips ◽  
...  
Keyword(s):  
Tp53 Mutation ◽  
Human Cancer ◽  
Atmospheric Oxygen ◽  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Tumour Suppressor ◽  
International Agency ◽  
Human Tumours ◽  
Clonal Cell Lines ◽  
Gene Tp53

DNA in dividing cells is prone to mutagenesis, with mutations making key contributions to human disease including cancer. The tumour suppressor gene TP53 is the most frequently mutated gene in human tumours. Here, we present a robust protocol for studying TP53 mutagenesis utilising human TP53 knock-in (Hupki) mouse embryonic fibroblasts (HUFs). In the HUF immortalisation assay (HIMA), primary HUFs are treated with known or suspected carcinogens at 3% oxygen and then transferred to 20% atmospheric oxygen to induce senescence. Cells containing mutations (e.g., in TP53) that allow bypassing of senescence eventually emerge as immortalised clonal cell lines after 2–3 months of serial passaging. As not all immortalised HUF cells contain TP53 mutations, we developed a Nutlin-3a counter-screen to select for TP53-mutated clones prior to sequencing. TP53 mutation spectra generated can be compared with those of human tumours recorded in the International Agency for Research on Cancer TP53 mutation database. Environmental mutagens that have demonstrated and validated the utility of the HIMA include ultraviolet radiation, aristolochic acid, and benzo[a]pyrene. The TP53 mutation patterns induced by these mutagens in the HIMA corresponded to those found in human tumours from patients exposed to these mutagens. The approach presented helps to deepen our understanding of human cancer aetiology.

scholarly journals Putative tumour suppressor gene necdin is hypermethylated and mutated in human cancer

2013 ◽  
Vol 108 (6) ◽  
pp. 1368-1377 ◽  
Author(s):  
L E De Faveri ◽  
C D Hurst ◽  
F M Platt ◽  
C F Taylor ◽  
J-A Roulson ◽  
...  
Keyword(s):  
Human Cancer ◽  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Tumour Suppressor

scholarly journals Cellular Distribution of Tumour Suppressor Protein p53 and High-Risk Human Papillomavirus (HPV)-18 E6 Fusion Protein in Wild-Type p53 Cell Lines

2008 ◽  
Vol 36 (5) ◽  
pp. 1015-1021 ◽  
Author(s):  
L Sun ◽  
G Gzhang ◽  
Z Li ◽  
T Lei ◽  
C Huang ◽  
...  
Keyword(s):  
High Risk ◽  
Fluorescent Protein ◽  
P53 Protein ◽  
Expression System ◽  
Human Papillomaviruses ◽  
Tumour Suppressor ◽  
Wild Type ◽  
Hpv E6 ◽  
Wild Type P53 ◽  
High Risk Hpv

Human papillomaviruses (HPVs) are very important pathogens that can be classified as high- and low-risk types based on the lesions they cause. Mucosal high-risk HPV E6 can target and degrade the tumour suppressor p53, hence it is recognized as the major cause of cervical cancer, however, due to a lack of reliable anti-E6 antibodies, the distribution of high-risk HPV E6 protein remains elusive. The present study, therefore, used a mammalian green fluorescent protein (GFP) expression system to express GFP-18 E6 fusion proteins in wild-type p53 cells, SMMC-7721 and HCT116, in order to trace the location and expression of HPV E6 and p53 protein. Following transfection, expression of GFP-18 E6 was found to be located in the nucleus, and endogenous wild-type p53 was also located there with GFP-18 E6.

Evidence for Mutant p53 Gain-of-Function Effects in Normal Haemopoietic Cells and Myc-Driven Lymphoma

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3589-3589
Author(s):  
Brandon James Aubrey ◽  
Andreas Strasser ◽  
Gemma Kelly ◽  
Lin Tai ◽  
Marco Herold
Keyword(s):  
Cell Death ◽  
Human Cancer ◽  
P53 Protein ◽  
Dominant Negative ◽  
Mutant P53 ◽  
P53 Mutations ◽  
Wild Type ◽  
Over Expression ◽  
Wild Type P53

Abstract Deregulated c-MYC expression and mutations in p53 are among the most common changes detected in human cancer. It is now established that mutant p53 proteins confer a poor prognosis in human cancer through both loss of wild-type p53 activity as well as various proposed gain-of-function properties. The specific role of mutant p53 in MYC-driven tumorigenesis is not known. The Eμ-Myc mouse model carries a c-Myc transgene under the control of the immunoglobulin heavy chain gene enhancer (Eμ), recapitulating the chromosomal translocation underlying human Burkitt Lymphoma (BL). These mice develop aggressive pre-B or B cell lymphomas and ~20% of those tumours exhibit p53 mutations. We have shown that MYC-driven lymphomas are exquisitely dependent on the pro-survival BCL-2 family member MCL-1 such that loss of a single allele of Mcl-1 leads to dramatic tumour regression and prolonged animal survival. Interestingly, we found that this dependency on MCL-1 is reduced, but not completely ablated, by the presence of a p53 mutation. This suggests an important role for mutant p53 in the sustained survival of MYC-driven lymphomas. We are investigating the effects of five different mutant mouse p53 proteins (V170M, I192S, G280, R246Q, R270H) on tumour initiation, sustained growth and chemoresistance in the Eμ-Myc mouse model. We are further examining the effect of p53 mutations on MCL-1 dependence by using a floxed Mcl-1 gene and a tamoxifen-inducible Cre-recombinase in established Eμ-Myc lymphomas. Preliminary data suggest that both loss of wild-type p53 function as well as retroviral over-expression of mutant p53 can compensate for reduced levels of MCL-1 (loss of one Mcl-1 allele). The underlying mechanisms for this are under investigation. The role of mutant p53 in lymphoma cell survival has been further examined in Eμ-Myc lymphoma-derived cell lines. Enforced over-expression of mutant p53 in cell lines containing wild-type p53 impaired induction of apoptosis by Nutlin3A, an inhibitor of Mdm-2 (the major negative regulator of p53). Remarkably, Nutlin-3a-induced apoptosis was impaired although it caused substantial transcriptional induction of the p53 apoptosis effectors, Puma and Noxa. Importantly, different mutant p53 proteins conferred different levels of protection against cell death. The observed protection against cell death may be partly due to dominant-negative effects of mutant p53, however, it does not appear to be robust enough to account for the extent of cell survival. Furthermore, mutant p53 conferred resistance to docetaxol, which is thought to induce cell death through predominantly p53-independent mechanisms. These data suggest that mutant p53 can protect against both p53-dependent and p53-independent cell death processes. Conversely, transcriptional induction of Noxa and Puma implies that “p53-restoration therapy” may remain a feasible treatment strategy even in tumours that bear mutations in p53 and that the role of a dominant-negative effect for some mutant p53 proteins may be less important than previously considered, at least in lymphoma cells. We are also examining the effect of mutant p53 on lymphoma development utilizing a hematopoietic reconstitution model and retroviral over-expression of mutant p53 proteins. The different mutant p53 proteins investigated exhibited distinct effects during tumorigenesis. The R246Q mutant p53 protein markedly accelerated lymphoma development in the context of MYC over-expression. The R246Q mutant p53 protein demonstrated strong selection in p53-deficient (p53-/-) hematopoietic cells during reconstitution indicative of an advantageous activity in emergency hematopoiesis. Overall, these findings provide evidence for a positive oncogenic role of mutant p53 in hematopoietic cells that provides a particularly potent selective advantage in the context of MYC driven lymphoma development. Importantly, different p53 mutations exhibit different functional properties such that different p53 mutations are likely to be associated with distinct risk in human malignant disease. Disclosures No relevant conflicts of interest to declare.

scholarly journals Failure of wild-type p53 gene therapy in human cancer cells expressing a mutant p53 protein

Gene Therapy ◽  
1999 ◽  
Vol 6 (1) ◽  
pp. 22-33 ◽  
Author(s):  
A Vinyals ◽  
M A Peinado ◽  
M Gonzalez-Garrigues ◽  
M Monzó ◽  
R D Bonfil ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Cancer Cells ◽  
Human Cancer ◽  
P53 Protein ◽  
P53 Gene ◽  
Mutant P53 ◽  
Wild Type ◽  
Human Cancer Cells ◽  
Wild Type P53

scholarly journals The Antiapoptotic RBM5/LUCA-15/H37 Gene and Its Role in Apoptosis and Human Cancer: Research Update

2006 ◽  
Vol 6 ◽  
pp. 1705-1712 ◽  
Author(s):  
Mirna M Maarabouni ◽  
Gwyn T Williams
Keyword(s):  
Gene Locus ◽  
Human Cancer ◽  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Tumour Suppressor ◽  
Suppressor Activity ◽  
Major Significance ◽  
Tumour Suppressor Activity ◽  
Alternatively Spliced ◽  
Candidate Tumour Suppressor

The candidate tumour-suppressor gene, LUCA-15/RBM5/H37, maps to the lung cancer tumour-suppressor locus 3p21.3. The LUCA-15 gene locus encodes at least four alternatively spliced transcripts that have been shown to function as regulators of apoptosis, a fact which may have major significance in tumour regulation. This review highlights recent evidence that further implicates the LUCA-15 locus in the control of apoptosis and cell proliferation, and focuses on the observations that confirm the tumour-suppressor activity of this gene.

scholarly journals Mutant p53 as a Regulator and Target of Autophagy

2021 ◽  
Vol 10 ◽  
Author(s):  
Yong Shi ◽  
Erik Norberg ◽  
Helin Vakifahmetoglu-Norberg
Keyword(s):  
Tumor Suppressor ◽  
High Frequency ◽  
Human Cancer ◽  
Cell Metabolism ◽  
Suppressor Gene ◽  
Mutant P53 ◽  
Wild Type ◽  
Complex Action ◽  
Wild Type P53

One of the most notoriously altered genes in human cancer is the tumor-suppressor TP53, which is mutated with high frequency in more cancers than any other tumor suppressor gene. Beyond the loss of wild-type p53 functions, mutations in the TP53 gene often lead to the expression of full-length proteins with new malignant properties. Among the defined oncogenic functions of mutant p53 is its effect on cell metabolism and autophagy. Due to the importance of autophagy as a stress adaptive response, it is frequently dysfunctional in human cancers. However, the role of p53 is enigmatic in autophagy regulation. While the complex action of the wild-type p53 on autophagy has extensively been described in literature, in this review, we focus on the conceivable role of distinct mutant p53 proteins in regulating different autophagic pathways and further discuss the available evidence suggesting a possible autophagy stimulatory role of mutant p53. Moreover, we describe the involvement of different autophagic pathways in targeting and degrading mutant p53 proteins, exploring the potential strategies of targeting mutant p53 in cancer by autophagy.

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