Tumor suppressor p53: analysis of wild-type and mutant p53 complexes.

It has been suggested that the dominant effect of mutant p53 on tumor progression may reflect the mutant protein binding to wild-type p53, with inactivation of suppressor function. To date, evidence for wild-type/mutant p53 complexes involves p53 from different species. To investigate wild-type/mutant p53 complexes in relation to natural tumor progression, we sought to identify intraspecific complexes, using murine p53. The mutant phenotype p53-246(0) was used because this phenotype is immunologically distinct from wild-type p53-246+ and thus permits immunological analysis for wild-type/mutant p53 complexes. The p53 proteins were derived from genetically defined p53 cDNAs expressed in vitro and also from phenotypic variants of p53 expressed in vivo. We found that the mutant p53 phenotype was able to form a complex with the wild type when the two p53 variants were cotranslated. When mixed in their native states (after translation), the wild-type and mutant p53 proteins did not exhibit any binding affinity for each other in vitro. Under identical conditions, complexes of wild-type human and murine p53 proteins were formed. For murine p53, both the wild-type and mutant p53 proteins formed high-molecular-weight complexes when translated in vitro. This oligomerization appeared to involve the carboxyl terminus, since truncated p53 (amino acids 1 to 343) did not form complexes. We suggest that the ability of the mutant p53 phenotype to complex with wild type during cotranslation may contribute to the transforming function of activated mutants of p53 in vivo.

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Astrocytes derived from p53-deficient mice provide a multistep in vitro model for development of malignant gliomas.

Molecular and Cellular Biology ◽

10.1128/mcb.15.8.4249 ◽

1995 ◽

Vol 15 (8) ◽

pp. 4249-4259 ◽

Cited By ~ 65

Author(s):

A M Yahanda ◽

J M Bruner ◽

L A Donehower ◽

R S Morrison

Keyword(s):

Genomic Instability ◽

Malignant Transformation ◽

Nude Mice ◽

Malignant Gliomas ◽

Early Event ◽

Wild Type ◽

Early Passage ◽

Wild Type P53

Loss or mutation of p53 is thought to be an early event in the malignant transformation of many human astrocytic tumors. To better understand the role of p53 in their growth and transformation, we developed a model employing cultured neonatal astrocytes derived from mice deficient in one (p53 +/-) or both (p53 -/-) p53 alleles, comparing them with wild-type (p53 +/+) cells. Studies of in vitro and in vivo growth and transformation were performed, and flow cytometry and karyotyping were used to correlate changes in growth with genomic instability. Early-passage (EP) p53 -/- astrocytes achieved higher saturation densities and had more rapid growth than EP p53 +/- and +/+ cells. The EP p53 -/- cells were not transformed, as they were unable to grow in serum-free medium or in nude mice. With continued passaging, p53 -/- cells exhibited a multistep progression to a transformed phenotype. Late-passage p53 -/- cells achieved saturation densities 50 times higher than those of p53 +/+ cells and formed large, well-vascularized tumors in nude mice. p53 +/- astrocytes exhibited early loss of the remaining wild-type p53 allele and then evolved in a manner phenotypically similar to p53 -/- astrocytes. In marked contrast, astrocytes retaining both wild-type p53 alleles never exhibited a transformed phenotype and usually senesced after 7 to 10 passages. Dramatic alterations in ploidy and karyotype occurred and were restricted to cells deficient in wild-type p53 following repeated passaging. The results of these studies suggest that loss of wild-type p53 function promotes genomic instability, accelerated growth, and malignant transformation in astrocytes.

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Wild Type p53 Gene Sensitizes Rat C6 Glioma Cells to HSV-TK/ACV Treatment In Vitro and In Vivo

Pathology & Oncology Research ◽

10.1007/s12253-009-9240-3 ◽

2010 ◽

Vol 16 (4) ◽

pp. 509-514 ◽

Cited By ~ 4

Author(s):

Qiang Huang ◽

Zhibo Xia ◽

Yongping You ◽

Peiyu Pu

Keyword(s):

Glioma Cells ◽

P53 Gene ◽

C6 Glioma ◽

C6 Glioma Cells ◽

Wild Type ◽

Wild Type P53 ◽

Rat C6 Glioma

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Targeting mutant p53-expressing tumours with a T cell receptor-like antibody specific for a wild-type antigen

Nature Communications ◽

10.1038/s41467-019-13305-z ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 5

Author(s):

Lionel Low ◽

Angeline Goh ◽

Joanna Koh ◽

Samantha Lim ◽

Cheng-I Wang

Keyword(s):

Cell Receptor ◽

Class I ◽

Human Antibody ◽

Mutant P53 ◽

Wild Type ◽

Class I Mhc ◽

Type Antigen ◽

Wide Range

AbstractAccumulation of mutant p53 proteins is frequently found in a wide range of cancers. While conventional antibodies fail to target intracellular proteins, proteosomal degradation results in the presentation of p53-derived peptides on the tumour cell surface by class I molecules of the major histocompatibility complex (MHC). Elevated levels of such p53-derived peptide-MHCs on tumour cells potentially differentiate them from healthy tissues. Here, we report the engineering of an affinity-matured human antibody, P1C1TM, specific for the unmutated p53125-134 peptide in complex with the HLA-A24 class I MHC molecule. We show that P1C1TM distinguishes between mutant and wild-type p53 expressing HLA-A24+ cells, and mediates antibody dependent cellular cytotoxicity of mutant p53 expressing cells in vitro. Furthermore, we show that cytotoxic PNU-159682-P1C1TM drug conjugates specifically inhibit growth of mutant p53 expressing cells in vitro and in vivo. Hence, p53-associated peptide-MHCs are attractive targets for the immunotherapy against mutant p53 expressing tumours.

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Expression of Wild-Type p53 by Curcumin, Alpinetin and Flavokawain B in Colorectal Cancer cells Expressing R273H Mutant p53

Nigerian Journal of Basic and Applied Sciences ◽

10.4314/njbas.v27i2.12 ◽

2020 ◽

Vol 27 (2) ◽

pp. 88-94

Author(s):

I. Malami ◽

A. Muhammad ◽

I.B. Abubakar ◽

A.M. Alhassan

Keyword(s):

Bioactive Compounds ◽

Mutant P53 ◽

Wild Type ◽

P53 Expression ◽

Gene And Protein Expression ◽

Colorectal Cancer Cells ◽

Binding Core ◽

Wild Type P53 ◽

Dose Dependent

A mutation in p53 is frequently reported in nearly 50% of all of human cancers arising from DNA-binding core domain of p53. DNA-contact mutant R273H rendered p53 at dysfunctional state due to the substitution of single residue Arg273 for His273. Here, natural bioactive compounds curcumin, alpinetin and flavokawain B were investigated for possible stabilisation of wild-type p53 expression in vitro using HT-29 cells harbouring R273H rendered p53. Accordingly, all the bioactive compounds were able to induce the expression of wild-type p53 both at the levels of gene and protein expression. A dose-dependent induction of p53 was evident at 12.5, 25 and 50 μM concentration. The present study has shown that the bioactive compounds may have restored the wild-type p53 functional activity in tumour cells expressing R273H mutant p53. Keywords: Curcumin, Alpinetin, Flavokawain B, p53, R273H

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A potent CBP/p300-Snail interaction inhibitor suppresses tumor growth and metastasis in wild-type p53-expressing cancer

Science Advances ◽

10.1126/sciadv.aaw8500 ◽

2020 ◽

Vol 6 (17) ◽

pp. eaaw8500

Author(s):

Hong-Mei Li ◽

Yan-Ran Bi ◽

Yang Li ◽

Rong Fu ◽

Wen-Cong Lv ◽

...

Keyword(s):

Tumor Growth ◽

Epithelial Mesenchymal Transition ◽

Therapeutic Effects ◽

Creb Binding Protein ◽

Wild Type ◽

Mesenchymal Transition ◽

Patients With Cancer ◽

Wild Type P53

The zinc finger transcription factor Snail is aberrantly activated in many human cancers and associated with poor prognosis. Therefore, targeting Snail is expected to exert therapeutic benefit in patients with cancer. However, Snail has traditionally been considered “undruggable,” and no effective pharmacological inhibitors have been identified. Here, we found a small-molecule compound CYD19 that forms a high-affinity interaction with the evolutionarily conserved arginine-174 pocket of Snail protein. In aggressive cancer cells, CYD19 binds to Snail and thus disrupts Snail’s interaction with CREB-binding protein (CBP)/p300, which consequently impairs CBP/p300-mediated Snail acetylation and then promotes its degradation through the ubiquitin-proteasome pathway. Moreover, CYD19 restores Snail-dependent repression of wild-type p53, thus reducing tumor growth and survival in vitro and in vivo. In addition, CYD19 reverses Snail-mediated epithelial-mesenchymal transition (EMT) and impairs EMT-associated tumor invasion and metastasis. Our findings demonstrate that pharmacologically targeting Snail by CYD19 may exert potent therapeutic effects in patients with cancer.

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Identification of a minimal transforming domain of p53: negative dominance through abrogation of sequence-specific DNA binding.

Molecular and Cellular Biology ◽

10.1128/mcb.12.12.5581 ◽

1992 ◽

Vol 12 (12) ◽

pp. 5581-5592 ◽

Cited By ~ 224

Author(s):

E Shaulian ◽

A Zauberman ◽

D Ginsberg ◽

M Oren

Keyword(s):

Dna Binding ◽

Point Mutation ◽

P53 Gene ◽

Dominant Negative ◽

Mutant P53 ◽

Wild Type ◽

Transforming Activity ◽

Wild Type P53 ◽

Negative Dominance

Mutations in the p53 gene are most frequent in cancer. Many p53 mutants possess transforming activity in vitro. In cells transformed by such mutants, the mutant protein is oligomerized with endogenous cell p53. To determine the relevance of oligomerization for transformation, miniproteins containing C-terminal portions of p53 were generated. These miniproteins, although carrying no point mutation, transformed at least as efficiently as full-length mutant p53. Transforming activity was coupled with the ability to oligomerize with wild-type p53, as well as with the ability to abrogate sequence-specific DNA binding by coexpressed wild-type p53. These findings suggest that p53-mediated transformation may operate through a dominant negative mechanism, involving the generation of DNA binding-incompetent oligomers.

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Dual inhibition of MDMX and MDM2 as a therapeutic strategy in leukemia

Science Translational Medicine ◽

10.1126/scitranslmed.aao3003 ◽

2018 ◽

Vol 10 (436) ◽

pp. eaao3003 ◽

Cited By ~ 58

Author(s):

Luis A. Carvajal ◽

Daniela Ben Neriah ◽

Adrien Senecal ◽

Lumie Benard ◽

Victor Thiruthuvanathan ◽

...

Keyword(s):

Tumor Suppressor ◽

Single Molecule ◽

Cellular Proliferation ◽

Wild Type ◽

Suppressor Activity ◽

Mouse Double Minute ◽

Double Minute ◽

Wild Type P53

The tumor suppressor p53 is often inactivated via its interaction with endogenous inhibitors mouse double minute 4 homolog (MDM4 or MDMX) or mouse double minute 2 homolog (MDM2), which are frequently overexpressed in patients with acute myeloid leukemia (AML) and other cancers. Pharmacological disruption of both of these interactions has long been sought after as an attractive strategy to fully restore p53-dependent tumor suppressor activity in cancers with wild-type p53. Selective targeting of this pathway has thus far been limited to MDM2-only small-molecule inhibitors, which lack affinity for MDMX. We demonstrate that dual MDMX/MDM2 inhibition with a stapled α-helical peptide (ALRN-6924), which has recently entered phase I clinical testing, produces marked antileukemic effects. ALRN-6924 robustly activates p53-dependent transcription at the single-cell and single-molecule levels and exhibits biochemical and molecular biological on-target activity in leukemia cells in vitro and in vivo. Dual MDMX/MDM2 inhibition by ALRN-6924 inhibits cellular proliferation by inducing cell cycle arrest and apoptosis in cell lines and primary AML patient cells, including leukemic stem cell–enriched populations, and disrupts functional clonogenic and serial replating capacity. Furthermore, ALRN-6924 markedly improves survival in AML xenograft models. Our study provides mechanistic insight to support further testing of ALRN-6924 as a therapeutic approach in AML and other cancers with wild-type p53.

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CP-31398 Restores DNA-binding Activity to Mutant p53in Vitrobut Does Not Affect p53 Homologs p63 and p73

Journal of Biological Chemistry ◽

10.1074/jbc.m401854200 ◽

2004 ◽

Vol 279 (44) ◽

pp. 45887-45896 ◽

Cited By ~ 45

Author(s):

Mark J. Demma ◽

Serena Wong ◽

Eugene Maxwell ◽

Bimalendu Dasmahapatra

Keyword(s):

Dna Binding ◽

Mammalian Cells ◽

P53 Protein ◽

Binding Activity ◽

Mutant P53 ◽

Dependent Manner ◽

Wild Type ◽

Dna Binding Activity

The p53 protein plays a major role in the maintenance of genome stability in mammalian cells. Mutations of p53 occur in over 50% of all cancers and are indicative of highly aggressive cancers that are hard to treat. Recently, there has been a high degree of interest in therapeutic approaches to restore growth suppression functions to mutant p53. Several compounds have been reported to restore wild type function to mutant p53. One such compound, CP-31398, has been shown effectivein vivo, but questions have arisen to whether it actually affects p53. Here we show that mutant p53, isolated from cells treated with CP-31398, is capable of binding to p53 response elementsin vitro. We also show the compound restores DNA-binding activity to mutant p53 in cells as determined by a chromatin immunoprecipitation assay. In addition, using purified p53 core domain from two different hotspot mutants (R273H and R249S), we show that CP-31398 can restore DNA-binding activity in a dose-dependent manner. Using a quantitative DNA binding assay, we also show that CP-31398 increases significantly the amount of mutant p53 that binds to cognate DNA (Bmax) and its affinity (Kd) for DNA. The compound, however, does not affect the affinity (Kdvalue) of wild type p53 for DNA and only increasesBmaxslightly. In a similar assay PRIMA1 does not have any effect on p53 core DNA-binding activity. We also show that CP-31398 had no effect on the DNA-binding activity of p53 homologs p63 and p73.

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Adenovirus mediated p53 tumour suppressor gene therapy for human gastric cancer cells in vitro and in vivo

Gut ◽

10.1136/gut.44.3.366 ◽

1999 ◽

Vol 44 (3) ◽

pp. 366-371 ◽

Cited By ~ 23

Author(s):

M Ohashi ◽

F Kanai ◽

H Ueno ◽

T Tanaka ◽

K Tateishi ◽

...

Keyword(s):

Gastric Cancer ◽

Gene Therapy ◽

P53 Gene ◽

Human Gastric Cancer ◽

Wild Type ◽

Gastric Cancer Cells ◽

Gastric Cancer Cell Lines ◽

Wild Type P53

BACKGROUND/AIMSGastric cancer is one of the most prevalent forms of cancer in East Asia. Point mutation of the p53 gene has been reported in more than 60% of cases of gastric cancer and can lead to genetic instability and uncontrolled cell proliferation. The purpose of this investigation was to evaluate the potential of p53 gene therapy for gastric cancer.METHODSThe responses of human gastric cancer cell lines, MKN1, MKN7, MKN28, MKN45, and TMK-1, to recombinant adenoviruses encoding wild type p53 (AdCAp53) were analysed in vitro. The efficacy of the AdCAp53 treatment for MKN1 and MKN45 subcutaneous tumours in nude mice was assessed in vivo.RESULTSp53-specific growth inhibition was observed in vitro in two of four gastric cancer cell lines with mutated p53, but not in the wild type p53 cell line. The mechanism of the killing of gastric cancer cells by AdCAp53 was found, by flow cytometric analysis and detection of DNA fragmentation, to be apoptosis. In vivo studies showed that the growth of subcutaneous tumours of p53 mutant MKN1 cells was significantly inhibited by direct injection of AdCAp53, but no significant growth inhibition was detected in the growth of p53 wild type MKN45 tumours.CONCLUSIONSAdenovirus mediated reintroduction of wild type p53 is a potential clinical utility in gene therapy for gastric cancers.

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