Mutant p53 Sequestration of the MDM2 Acidic Domain Inhibits E3 Ligase Activity

ABSTRACT Missense p53 mutants often accumulate in tumors and drive progression through gain of function. MDM2 efficiently degrades wild-type p53 but fails to degrade mutant p53 in tumor cells. Previous studies revealed that mutant p53 inhibits MDM2 autoubiquitination, suggesting that the interaction inhibits MDM2 E3 activity. Recent work showed that MDM2 E3 activity is stimulated by intramolecular interaction between the RING and acidic domains. Here, we show that in the mutant p53-MDM2 complex, the mutant p53 core domain binds to the MDM2 acidic domain with significantly higher avidity than wild-type p53. The mutant p53-MDM2 complex is deficient in catalyzing ubiquitin release from the activated E2 conjugating enzyme. An MDM2 construct with extra copies of the acidic domain is resistant to inhibition by mutant p53 and efficiently promotes mutant p53 ubiquitination and degradation. The results suggest that mutant p53 interferes with the intramolecular autoactivation mechanism of MDM2, contributing to reduced ubiquitination and increased accumulation in tumor cells.

Download Full-text

Mutant p53 Disrupts MCF-10A Cell Polarity in Three-dimensional Culture via Epithelial-to-mesenchymal Transitions

Journal of Biological Chemistry ◽

10.1074/jbc.m110.214585 ◽

2011 ◽

Vol 286 (18) ◽

pp. 16218-16228 ◽

Cited By ~ 60

Author(s):

Yanhong Zhang ◽

Wensheng Yan ◽

Xinbin Chen

Keyword(s):

Cell Polarity ◽

Expression Patterns ◽

Ectopic Expression ◽

Three Dimensional ◽

Mutant P53 ◽

Wild Type ◽

Gain Of Function ◽

Three Dimensional Culture ◽

Wild Type P53 ◽

E Cadherin

Mutant p53 is not only deficient in tumor suppression but also acquires additional activity, called gain of function. Mutant p53 gain of function is recapitulated in knock-in mice that carry one null allele and one mutant allele of the p53 gene. These knock-in mice develop aggressive tumors compared with p53-null mice. Recently, we and others showed that tumor cells carrying a mutant p53 are addicted to the mutant for cell survival and resistance to DNA damage. To further define mutant p53 gain of function, we used the MCF-10A three-dimensional model of mammary morphogenesis. MCF-10A cells in three-dimensional culture undergo a series of morphological changes and form polarized and growth-arrested spheroids with hollow lumen, which resembles normal glandular architectures in vivo. Here, we found that endogenous wild-type p53 in MCF-10A cells was not required for acinus formation, but knockdown of endogenous wild-type p53 (p53-KD) led to partial clearance of cells in the lumen due to decreased apoptosis. Consistent with this, p53-KD altered expression patterns of the cell adhesion molecule E-cadherin, the cytoskeletal marker β-catenin, and the extracellular matrix protein laminin V. We also found that ectopic expression of the mutant G245S led to a phenotype similar to p53-KD, whereas a combination of ectopic expression of siRNA-resistant G245S with p53-KD led to a less cleared lumen. In contrast, ectopic expression of mutant R248W, R175H, and R273H disrupted normal acinus architectures with filled lumen and led to formation of irregular and multiacinus structures regardless of p53-KD. In addition, these mutants altered normal expression patterns and/or levels of E-cadherin, β-catenin, laminin V, and tight junction marker ZO-1. Furthermore, epithelial-to-mesenchymal transitions (EMT) markers, Snail, Slug, and Twist, were highly induced by mutant p53 and/or p53-KD. Together, we postulate that EMT represents a mutant p53 gain of function and mutant p53 alters cell polarity via EMT.

Download Full-text

Mutant p53: Gain-of-Function Oncoproteins and Wild-Type p53 Inactivators

Biological Chemistry ◽

10.1515/bc.1999.108 ◽

1999 ◽

Vol 380 (7-8) ◽

Cited By ~ 55

Author(s):

K. Roemer

Keyword(s):

Mutant P53 ◽

Wild Type ◽

Gain Of Function ◽

Wild Type P53

Download Full-text

Ubiquitination and Degradation of Mutant p53

Molecular and Cellular Biology ◽

10.1128/mcb.00050-07 ◽

2007 ◽

Vol 27 (23) ◽

pp. 8284-8295 ◽

Cited By ~ 134

Author(s):

Natalia Lukashchuk ◽

Karen H. Vousden

Keyword(s):

Tumor Cells ◽

Ubiquitin Ligase ◽

Ubiquitin Ligases ◽

Mutant P53 ◽

Wild Type ◽

Independent Manner ◽

Interacting Protein ◽

C Terminus ◽

Wild Type P53 ◽

Mutant Forms

ABSTRACT While wild-type p53 is normally a rapidly degraded protein, mutant forms of p53 are stabilized and accumulate to high levels in tumor cells. In this study, we show that mutant and wild-type p53 proteins are ubiquitinated and degraded through overlapping but distinct pathways. While Mdm2 can drive the degradation of both mutant and wild-type p53, our data suggest that the ability of Mdm2 to function as a ubiquitin ligase is less important in the degradation of mutant p53, which is heavily ubiquitinated in an Mdm2-independent manner. Our initial attempts to identify ubiquitin ligases that are responsible for the ubiquitination of mutant p53 have suggested a role for the chaperone-associated ubiquitin ligase CHIP (C terminus of Hsc70-interacting protein), although other unidentified ubiquitin ligases also appear to contribute. The contribution of Mdm2 to the degradation of mutant p53 may reflect the ability of Mdm2 to deliver the ubiquitinated mutant p53 to the proteasome.

Download Full-text

Gain-of-function mutant p53 in cancer progression and therapy

Journal of Molecular Cell Biology ◽

10.1093/jmcb/mjaa040 ◽

2020 ◽

Vol 12 (9) ◽

pp. 674-687 ◽

Cited By ~ 4

Author(s):

Cen Zhang ◽

Juan Liu ◽

Dandan Xu ◽

Tianliang Zhang ◽

Wenwei Hu ◽

...

Keyword(s):

Cancer Progression ◽

P53 Gene ◽

Amino Acid Difference ◽

Protein Accumulation ◽

Mutant P53 ◽

P53 Mutations ◽

Wild Type ◽

Gain Of Function ◽

Human Cancers ◽

Wild Type P53

Abstract p53 is a key tumor suppressor, and loss of p53 function is frequently a prerequisite for cancer development. The p53 gene is the most frequently mutated gene in human cancers; p53 mutations occur in >50% of all human cancers and in almost every type of human cancers. Most of p53 mutations in cancers are missense mutations, which produce the full-length mutant p53 (mutp53) protein with only one amino acid difference from wild-type p53 protein. In addition to loss of the tumor-suppressive function of wild-type p53, many mutp53 proteins acquire new oncogenic activities independently of wild-type p53 to promote cancer progression, termed gain-of-function (GOF). Mutp53 protein often accumulates to very high levels in cancer cells, which is critical for its GOF. Given the high mutation frequency of the p53 gene and the GOF activities of mutp53 in cancer, therapies targeting mutp53 have attracted great interest. Further understanding the mechanisms underlying mutp53 protein accumulation and GOF will help develop effective therapies treating human cancers containing mutp53. In this review, we summarize the recent advances in the studies on mutp53 regulation and GOF as well as therapies targeting mutp53 in human cancers.

Download Full-text

2-[(4-Hydroxybenzyl) Amino] Phenol (HBAP) Restores the Mutated p53 to the Level Similar to That of Wild-Type p53 Protein and Inhibits Breast Cancer Growth in vivo to by Inducing Tumor Cells Apoptosis

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2020.574799 ◽

2020 ◽

Vol 8 ◽

Author(s):

Chenxi Xu ◽

Jianjian Zhuang ◽

Xiaobo Zhang

Keyword(s):

Breast Cancer ◽

Tumor Cells ◽

Deep Sea ◽

Breast Cancer Cells ◽

P53 Protein ◽

Mutant P53 ◽

Wild Type ◽

Amino Phenol ◽

Wild Type P53

P53 is a transcriptional factor that plays important roles in apoptosis and is mutated in more than 50% of tumor cells. However, the restoration of mutated p53 to the level similar to wild-type p53 by a natural compound has not been explored intensively. In this study, the 2-[(4-hydroxybenzyl) amino] phenol (HBAP) compound, obtained from deep-sea virus-challenged thermophile Geobacillus sp. E263, interacted specifically with the mutated p53 protein. HBAP was able to induce apoptosis of p53-mutated breast cancer cells, but not normal breast cells and p53-unmutated breast cancer cells. HBAP activated the mutant p53 transcriptional activity by restoring the function of mutant p53 to that of wild-type p53. Further analysis indicated that HBAP bound only to the DNA binding domain of mutant p53 and that the interaction was dependent on the HBAP hydroxyl groups. In vivo data demonstrated that HBAP was toxicity-free and could suppress tumor growth by inducing tumor cell apoptosis. Therefore our findings revealed that recovering mutated p53 function to that of wild-type p53 caused by HBAP triggered cancer cell apoptosis and that metabolites from deep-sea virus-challenged thermophiles could be a promising source of anti-tumor drugs.

Download Full-text

Wild-type p53 oligomerizes more efficiently than p53 hot-spot mutants and overcomes mutant p53 gain-of-function via a “dominant-positive” mechanism

Oncotarget ◽

10.18632/oncotarget.25944 ◽

2018 ◽

Vol 9 (62) ◽

pp. 32063-32080 ◽

Cited By ~ 5

Author(s):

Dawid Walerych ◽

Magdalena Pruszko ◽

Lukasz Zyla ◽

Michalina Wezyk ◽

Katarzyna Gaweda-Walerych ◽

...

Keyword(s):

Hot Spot ◽

Mutant P53 ◽

Wild Type ◽

Gain Of Function ◽

Wild Type P53

Download Full-text

The effects of wild-type p53 tumor suppressor activity and mutant p53 gain-of-function on cell growth

Gene ◽

10.1016/s0378-1119(01)00696-5 ◽

2001 ◽

Vol 277 (1-2) ◽

pp. 15-30 ◽

Cited By ~ 151

Author(s):

Craig Cadwell ◽

Gerard P Zambetti

Keyword(s):

Cell Growth ◽

Tumor Suppressor ◽

Mutant P53 ◽

Wild Type ◽

Gain Of Function ◽

Suppressor Activity ◽

P53 Tumor Suppressor ◽

Tumor Suppressor Activity ◽

Wild Type P53

Download Full-text

Semi-Synthesis of Small Molecules of Aminocarbazoles: Tumor Growth Inhibition and Potential Impact on p53

Molecules ◽

10.3390/molecules26061637 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1637

Author(s):

Solida Long ◽

Joana B. Loureiro ◽

Carla Carvalho ◽

Luís Gales ◽

Lucília Saraiva ◽

...

Keyword(s):

Growth Inhibition ◽

Small Molecules ◽

Tumor Cells ◽

Mutant P53 ◽

Wild Type ◽

Naturally Occurring ◽

Growth Inhibitory ◽

Growth Inhibitory Activity ◽

Amino Derivatives ◽

Carbazole Alkaloids

The tumor suppressor p53 is inactivated by mutation in approximately 50% of human cancers. Small molecules that bind and stabilize those mutants may represent effective anticancer drugs. Herein, we report the tumor cell growth inhibitory activity of carbazole alkaloids and amino derivatives, as well as their potential activation of p53. Twelve aminocarbazole alkaloids were semi-synthesized from heptaphylline (1), 7-methoxy heptaphylline (2), and 7-methoxymukonal (3), isolated from Clausena harmandiana, using a reductive amination protocol. Naturally-occurring carbazoles 1–3 and their amino derivatives were evaluated for their potential effect on wild-type and mutant p53 activity using a yeast screening assay and on human tumor cell lines. Naturally-occurring carbazoles 1–3 showed the most potent growth inhibitory effects on wild-type p53-expressing cells, being heptaphylline (1) the most promising in all the investigated cell lines. However, compound 1 also showed growth inhibition against non-tumor cells. Conversely, semi-synthetic aminocarbazole 1d showed an interesting growth inhibitory activity in tumor cells expressing both wild-type and mutant p53, exhibiting low growth inhibition on non-tumor cells. The yeast assay showed a potential reactivation of mutant p53 by heptaphylline derivatives, including compound 1d. The results obtained indicate that carbazole alkaloids may represent a promising starting point to search for new mutp53-reactivating agents with promising applications in cancer therapy.

Download Full-text