Loss of peptidase D binding restores the tumor suppressor functions of oncogenic p53 mutants

AbstractTumor suppressor p53, a critical regulator of cell fate, is frequently mutated in cancer. Mutation of p53 abolishes its tumor-suppressing functions or endows oncogenic functions. We recently found that p53 binds via its proline-rich domain to peptidase D (PEPD) and is activated when the binding is disrupted. The proline-rich domain in p53 is rarely mutated. Here, we show that oncogenic p53 mutants closely resemble p53 in PEPD binding but are transformed into tumor suppressors, rather than activated as oncoproteins, when their binding to PEPD is disrupted by PEPD knockdown. Once freed from PEPD, p53 mutants undergo multiple posttranslational modifications, especially lysine 373 acetylation, which cause them to refold and regain tumor suppressor activities that are typically displayed by p53. The reactivated p53 mutants strongly inhibit cancer cell growth in vitro and in vivo. Our study identifies a cellular mechanism for reactivation of the tumor suppressor functions of oncogenic p53 mutants.

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Cloning and Characterization of SCHIP-1, a Novel Protein Interacting Specifically with Spliced Isoforms and Naturally Occurring Mutant NF2 Proteins

Molecular and Cellular Biology ◽

10.1128/mcb.20.5.1699-1712.2000 ◽

2000 ◽

Vol 20 (5) ◽

pp. 1699-1712 ◽

Cited By ~ 51

Author(s):

Laurence Goutebroze ◽

Estelle Brault ◽

Christian Muchardt ◽

Jacques Camonis ◽

Gilles Thomas

Keyword(s):

Tumor Suppressor ◽

Conformational Changes ◽

Posttranslational Modifications ◽

Coiled Coil ◽

Neurofibromatosis Type ◽

Immunofluorescent Staining ◽

Naturally Occurring ◽

Cellular Context

ABSTRACT The neurofibromatosis type 2 (NF2) protein, known as schwannomin or merlin, is a tumor suppressor involved in NF2-associated and sporadic schwannomas and meningiomas. It is closely related to the ezrin-radixin-moesin family members, implicated in linking membrane proteins to the cytoskeleton. The molecular mechanism allowing schwannomin to function as a tumor suppressor is unknown. In attempt to shed light on schwannomin function, we have identified a novel coiled-coil protein, SCHIP-1, that specifically associates with schwannomin in vitro and in vivo. Within its coiled-coil region, this protein is homologous to human FEZ proteins and the relatedCaenorhabditis elegans gene product UNC-76. Immunofluorescent staining of transiently transfected cells shows a partial colocalization of SCHIP-1 and schwannomin, beneath the cytoplasmic membrane. Surprisingly, immunoprecipitation assays reveal that in a cellular context, association with SCHIP-1 can be observed only with some naturally occurring mutants of schwannomin, or a schwannomin spliced isoform lacking exons 2 and 3, but not with the schwannomin isoform exhibiting growth-suppressive activity. Our observations suggest that SCHIP-1 interaction with schwannomin is regulated by conformational changes in schwannomin, possibly induced by posttranslational modifications, alternative splicing, or mutations.

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The REGγ inhibitor NIP30 increases sensitivity to chemotherapy in p53-deficient tumor cells

Nature Communications ◽

10.1038/s41467-020-17667-7 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Xiao Gao ◽

Qingwei Wang ◽

Ying Wang ◽

Jiang Liu ◽

Shuang Liu ◽

...

Keyword(s):

Chemotherapy Resistance ◽

Inhibitory Effect ◽

Chemotherapeutic Agents ◽

Serine Phosphorylation ◽

Cancer Cell Growth ◽

Rich Domain ◽

Novel Approach ◽

Growth Inhibitory

Abstract A major challenge in chemotherapy is chemotherapy resistance in cells lacking p53. Here we demonstrate that NIP30, an inhibitor of the oncogenic REGγ-proteasome, attenuates cancer cell growth and sensitizes p53-compromised cells to chemotherapeutic agents. NIP30 acts by binding to REGγ via an evolutionarily-conserved serine-rich domain with 4-serine phosphorylation. We find the cyclin-dependent phosphatase CDC25A is a key regulator for NIP30 phosphorylation and modulation of REGγ activity during the cell cycle or after DNA damage. We validate CDC25A-NIP30-REGγ mediated regulation of the REGγ target protein p21 in vivo using p53−/− and p53/REGγ double-deficient mice. Moreover, Phosphor-NIP30 mimetics significantly increase the growth inhibitory effect of chemotherapeutic agents in vitro and in vivo. Given that NIP30 is frequently mutated in the TCGA cancer database, our results provide insight into the regulatory pathway controlling the REGγ-proteasome in carcinogenesis and offer a novel approach to drug-resistant cancer therapy.

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PRMT4-Mediated Arginine Methylation Negatively Regulates Retinoblastoma Tumor Suppressor Protein and Promotes E2F-1 Dissociation

Molecular and Cellular Biology ◽

10.1128/mcb.00945-14 ◽

2014 ◽

Vol 35 (1) ◽

pp. 238-248 ◽

Cited By ~ 11

Author(s):

Kevin Y. Kim ◽

Don-Hong Wang ◽

Mel Campbell ◽

Steve B. Huerta ◽

Bogdan Shevchenko ◽

...

Keyword(s):

Cell Cycle ◽

Tumor Suppressor ◽

Posttranslational Modifications ◽

Transcriptional Activation ◽

Cell Cycle Control ◽

Arginine Methylation ◽

Reporter System ◽

Suppressor Activity

The retinoblastoma protein (pRb/p105) tumor suppressor plays a pivotal role in cell cycle regulation by blockage of the G1-to-S-phase transition. pRb tumor suppressor activity is governed by a variety of posttranslational modifications, most notably phosphorylation by cyclin-dependent kinase (Cdk) complexes. Here we report a novel regulation of pRb through protein arginine methyltransferase 4 (PRMT4)-mediated arginine methylation, which parallels phosphorylation. PRMT4 specifically methylates pRb at the pRb C-terminal domain (pRb Cterm) on arginine (R) residues R775, R787, and R798in vitroand R787in vivo. Arginine methylation is important for efficient pRb Ctermphosphorylation, as manifested by the reduced phosphorylation of a methylation-impaired mutant, pRb (R3K). A methylmimetic form of pRb, pRb (R3F), disrupts the formation of the E2F-1/DP1-pRb complex in cells as well as in an isolated system. Finally, studies using a Gal4–E2F-1 reporter system show that pRb (R3F) expression reduces the ability of pRb to repress E2F-1 transcriptional activation, while pRb (R3K) expression further represses E2F-1 transcriptional activation relative to that for cells expressing wild-type pRb. Together, our results suggest that arginine methylation negatively regulates the tumor suppressor function of pRb during cell cycle control, in part by creating a better substrate for Cdk complex phosphorylation and disrupting the interaction of pRb with E2F-1.

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ECRG4 as a novel tumor suppressor gene inhibits colorectal cancer cell growth in vitro and in vivo

Tumor Biology ◽

10.1007/s13277-015-4775-2 ◽

2016 ◽

Vol 37 (7) ◽

pp. 9111-9120 ◽

Cited By ~ 11

Author(s):

Zhengxu Cai ◽

Pin Liang ◽

Jize Xuan ◽

Jiajia Wan ◽

Huishu Guo

Keyword(s):

Colorectal Cancer ◽

Cell Growth ◽

Tumor Suppressor ◽

Tumor Suppressor Gene ◽

Cancer Cell ◽

Suppressor Gene ◽

Colorectal Cancer Cell ◽

Cancer Cell Growth

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Current Status of the Use of Multifunctional Enzymes as Anti-Cancer Drug Targets

Pharmaceutics ◽

10.3390/pharmaceutics14010010 ◽

2021 ◽

Vol 14 (1) ◽

pp. 10

Author(s):

Carla S. S. Teixeira ◽

Sérgio F. Sousa

Keyword(s):

Posttranslational Modifications ◽

Drug Targets ◽

Current Status ◽

Cancer Drug ◽

Cancer Cell Growth ◽

Anti Cancer ◽

Multifunctional Enzymes ◽

Potential Inhibitors

Fighting cancer is one of the major challenges of the 21st century. Among recently proposed treatments, molecular-targeted therapies are attracting particular attention. The potential targets of such therapies include a group of enzymes that possess the capability to catalyze at least two different reactions, so-called multifunctional enzymes. The features of such enzymes can be used to good advantage in the development of potent selective inhibitors. This review discusses the potential of multifunctional enzymes as anti-cancer drug targets along with the current status of research into four enzymes which by their inhibition have already demonstrated promising anti-cancer effects in vivo, in vitro, or both. These are PFK-2/FBPase-2 (involved in glucose homeostasis), ATIC (involved in purine biosynthesis), LTA4H (involved in the inflammation process) and Jmjd6 (involved in histone and non-histone posttranslational modifications). Currently, only LTA4H and PFK-2/FBPase-2 have inhibitors in active clinical development. However, there are several studies proposing potential inhibitors targeting these four enzymes that, when used alone or in association with other drugs, may provide new alternatives for preventing cancer cell growth and proliferation and increasing the life expectancy of patients.

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A multi-modal proteomics strategy for characterizing posttranslational modifications of tumor suppressor p53 reveals many sites but few modified forms

10.1101/455527 ◽

2018 ◽

Cited By ~ 2

Author(s):

Caroline J. DeHart ◽

Luca Fornelli ◽

Lissa C. Anderson ◽

Ryan T. Fellers ◽

Dan Lu ◽

...

Keyword(s):

Tumor Suppressor ◽

Posttranslational Modifications ◽

Direct Analysis ◽

Tumor Suppressor P53 ◽

Top Down ◽

Combinatorial Explosion ◽

Bottom Up ◽

Post Translational Modifications ◽

Chk1 Kinase

SummaryPost-translational modifications (PTMs) are found on most proteins, particularly on “hub” proteins like the tumor suppressor p53, which has over 100 possible PTM sites. Substantial crosstalk between PTM sites underlies the ability of such proteins to integrate diverse signals and coordinate downstream responses. However, disentangling the combinatorial explosion in global PTM patterns across an entire protein (“modforms”) has been challenging, as conventional peptide-based mass spectrometry strategies (so-called “bottom-up” MS) destroy such global correlations. Alternatively, direct analysis of intact and modified proteins using “top-down” MS retains global information. Here, we applied both strategies to recombinant p53 phosphorylated in vitro with Chk1 kinase, which exhibited 41 modified sites by bottom-up MS, but no more than 8 modified sites per molecule detected by top-down MS. This observation that many low-abundance modifications comprise relatively few modforms above a 1% threshold indicates that endogenous p53 PTM complexity may be more definable than previously thought.

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MicroRNA-211 Expression Promotes Colorectal Cancer Cell Growth In Vitro and In Vivo by Targeting Tumor Suppressor CHD5

PLoS ONE ◽

10.1371/journal.pone.0029750 ◽

2012 ◽

Vol 7 (1) ◽

pp. e29750 ◽

Cited By ~ 73

Author(s):

Chunxiao Cai ◽

Hassan Ashktorab ◽

Xiaowu Pang ◽

Yuan Zhao ◽

Wei Sha ◽

...

Keyword(s):

Colorectal Cancer ◽

Cell Growth ◽

Tumor Suppressor ◽

Cancer Cell ◽

Colorectal Cancer Cell ◽

Cancer Cell Growth

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Literature-based automated discovery of tumor suppressor p53 phosphorylation and inhibition by NEK2

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1806643115 ◽

2018 ◽

Vol 115 (42) ◽

pp. 10666-10671 ◽

Cited By ~ 13

Author(s):

Byung-Kwon Choi ◽

Tajhal Dayaram ◽

Neha Parikh ◽

Angela D. Wilkins ◽

Meena Nagarajan ◽

...

Keyword(s):

Tumor Suppressor ◽

Scientific Discovery ◽

Large Body ◽

Scientific Progress ◽

Biomedical Literature ◽

Tumor Suppressor P53 ◽

Bona Fide ◽

Automated Discovery

Scientific progress depends on formulating testable hypotheses informed by the literature. In many domains, however, this model is strained because the number of research papers exceeds human readability. Here, we developed computational assistance to analyze the biomedical literature by reading PubMed abstracts to suggest new hypotheses. The approach was tested experimentally on the tumor suppressor p53 by ranking its most likely kinases, based on all available abstracts. Many of the best-ranked kinases were found to bind and phosphorylate p53 (P value = 0.005), suggesting six likely p53 kinases so far. One of these, NEK2, was studied in detail. A known mitosis promoter, NEK2 was shown to phosphorylate p53 at Ser315 in vitro and in vivo and to functionally inhibit p53. These bona fide validations of text-based predictions of p53 phosphorylation, and the discovery of an inhibitory p53 kinase of pharmaceutical interest, suggest that automated reasoning using a large body of literature can generate valuable molecular hypotheses and has the potential to accelerate scientific discovery.

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