scholarly journals The Janus Face of p53-Targeting Ubiquitin Ligases

Cells ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1656 ◽  
Author(s):  
Qian Hao ◽  
Yajie Chen ◽  
Xiang Zhou
Keyword(s):  
Cancer Progression ◽  
Ubiquitin Ligases ◽  
Tp53 Gene ◽  
Mutant P53 ◽  
E3 Ubiquitin Ligases ◽  
Tumor Suppressor P53 ◽  
Wild Type ◽  
Cell Growth Arrest ◽  
Cancer Cell Survival ◽  
P53 Status

The tumor suppressor p53 prevents tumorigenesis and cancer progression by maintaining genomic stability and inducing cell growth arrest and apoptosis. Because of the extremely detrimental nature of wild-type p53, cancer cells usually mutate the TP53 gene in favor of their survival and propagation. Some of the mutant p53 proteins not only lose the wild-type activity, but also acquire oncogenic function, namely “gain-of-function”, to promote cancer development. Growing evidence has revealed that various E3 ubiquitin ligases are able to target both wild-type and mutant p53 for degradation or inactivation, and thus play divergent roles leading to cancer cell survival or death in the context of different p53 status. In this essay, we reviewed the recent progress in our understanding of the p53-targeting E3 ubiquitin ligases, and discussed the potential clinical implications of these E3 ubiquitin ligases in cancer therapy.

scholarly journals Antitumor Effects of PRIMA-1 and PRIMA-1Met (APR246) in Hematological Malignancies: Still a Mutant P53-Dependent Affair?

Cells ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 98
Author(s):  
Paola Menichini ◽  
Paola Monti ◽  
Andrea Speciale ◽  
Giovanna Cutrona ◽  
Serena Matis ◽  
...  
Keyword(s):  
Hematological Malignancies ◽  
Cell Metabolism ◽  
Therapy Response ◽  
Tp53 Gene ◽  
Suppressor Gene ◽  
Lower Percentage ◽  
Mutant P53 ◽  
Wild Type ◽  
Antitumor Effects ◽  
Tp53 Tumor Suppressor Gene

Because of its role in the regulation of the cell cycle, DNA damage response, apoptosis, DNA repair, cell migration, autophagy, and cell metabolism, the TP53 tumor suppressor gene is a key player for cellular homeostasis. TP53 gene is mutated in more than 50% of human cancers, although its overall dysfunction may be even more frequent. TP53 mutations are detected in a lower percentage of hematological malignancies compared to solid tumors, but their frequency generally increases with disease progression, generating adverse effects such as resistance to chemotherapy. Due to the crucial role of P53 in therapy response, several molecules have been developed to re-establish the wild-type P53 function to mutant P53. PRIMA-1 and its methylated form PRIMA-1Met (also named APR246) are capable of restoring the wild-type conformation to mutant P53 and inducing apoptosis in cancer cells; however, they also possess mutant P53-independent properties. This review presents the activities of PRIMA-1 and PRIMA-1Met/APR246 and describes their potential use in hematological malignancies.

scholarly journals A p53-Phosphoinositide Signalosome Regulates Nuclear Akt Activation

2021 ◽  
Author(s):  
Mo Chen ◽  
Suyong Choi ◽  
Tianmu Wen ◽  
Changliang Chen ◽  
Narendra Thapa ◽  
...  
Keyword(s):  
Genotoxic Stress ◽  
Akt Pathway ◽  
Mutant P53 ◽  
Tumor Suppressor P53 ◽  
Wild Type ◽  
Akt Activation ◽  
Pi3k Inhibitors ◽  
Phosphoinositide 3 Kinase ◽  
Induced Apoptosis ◽  
Dependent Mechanism

The tumor suppressor p53 and the phosphoinositide 3-kinase (PI3K)-Akt pathway have fundamental roles in regulating cell growth, apoptosis and are frequently mutated in cancer. Here, we show that genotoxic stress induces nuclear Akt activation by a p53-dependent mechanism that is independent from the canonical membrane-localized PI3K-Akt pathway. Upon genotoxic stress a nuclear p53-PI3,4,5P3 complex is generated in regions devoid of membranes by a nuclear PI3K, and this complex recruits all the kinases required to activate Akt and phosphorylate FOXOs, inhibiting DNA damage-induced apoptosis. Wild-type p53 activates nuclear Akt in an on/off fashion upon stress, whereas mutant p53 stimulates high basal Akt activity, indicating a fundamental difference. The nuclear p53-phosphoinositide signalosome is distinct from the canonical membrane-localized pathway and insensitive to PI3K inhibitors currently in the clinic, underscoring its therapeutic relevance.

scholarly journals Cytoplasmic p53 polypeptide is associated with ribosomes.

1997 ◽  
Vol 17 (6) ◽  
pp. 3146-3154 ◽  
Author(s):  
B M Fontoura ◽  
C A Atienza ◽  
E A Sorokina ◽  
T Morimoto ◽  
R B Carroll
Keyword(s):  
Sodium Dodecyl ◽  
Proteinase K ◽  
Mutant P53 ◽  
Tumor Suppressor P53 ◽  
Wild Type ◽  
Mcf7 Cells ◽  
Gapdh Mrna ◽  
5.8S Rrna ◽  
Proteinase K Treatment ◽  
Covalently Linked

Our previous finding that the tumor suppressor p53 is covalently linked to 5.8S rRNA suggested functional association of p53 polypeptide with ribosomes. p53 polypeptide is expressed at low basal levels in the cytoplasm of normal growing cells in the G1 phase of the cell cycle. We report here that cytoplasmic wild-type p53 polypeptide from both rat embryo fibroblasts and MCF7 cells and the A135V transforming mutant p53 polypeptide were found associated with ribosomes to various extents. Treatment of cytoplasmic extracts with RNase or puromycin in the presence of high salt, both of which are known to disrupt ribosomal function, dissociated p53 polypeptide from the ribosomes. In immunoprecipitates of p53 polypeptide-associated ribosomes, 5.8S rRNA was detectable only after proteinase K treatment, indicating all of the 5.8S rRNA in p53-associated ribosomes is covalently linked to protein. While 5.8S rRNA linked to protein was found in the immunoprecipitates of either wild-type or A135V mutant p53 polypeptide associated with ribosomes, little 5.8S rRNA was found in the immunoprecipitates of the slowly sedimenting p53 polypeptide, which was not associated with ribosomes. In contrast, 5.8S rRNA was liberated from bulk ribosomes by 1% sodium dodecyl sulfate, without digestion with proteinase K, indicating that these ribosomes contain 5.8S rRNA, which is not linked to protein. Immunoprecipitation of p53 polypeptide coprecipitated a small fraction of ribosomes. p53 mRNA immunoprecipitated with cytoplasmic p53 polypeptide, while GAPDH mRNA did not. These results show that cytoplasmic p53 polypeptide is associated with a subset of ribosomes, having covalently modified 5.8S rRNA.

scholarly journals E3 Ubiquitin Ligase TRIM Proteins, Cell Cycle and Mitosis

Cells ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 510 ◽  
Author(s):  
Santina Venuto ◽  
Giuseppe Merla
Keyword(s):  
Cell Cycle ◽  
Cancer Progression ◽  
Current Knowledge ◽  
Ubiquitin Ligases ◽  
Cell Protein ◽  
E3 Ubiquitin Ligases ◽  
Daughter Cells ◽  
Protein Ubiquitination ◽  
Functional Units ◽  
Trim Proteins

The cell cycle is a series of events by which cellular components are accurately segregated into daughter cells, principally controlled by the oscillating activities of cyclin-dependent kinases (CDKs) and their co-activators. In eukaryotes, DNA replication is confined to a discrete synthesis phase while chromosome segregation occurs during mitosis. During mitosis, the chromosomes are pulled into each of the two daughter cells by the coordination of spindle microtubules, kinetochores, centromeres, and chromatin. These four functional units tie chromosomes to the microtubules, send signals to the cells when the attachment is completed and the division can proceed, and withstand the force generated by pulling the chromosomes to either daughter cell. Protein ubiquitination is a post-translational modification that plays a central role in cellular homeostasis. E3 ubiquitin ligases mediate the transfer of ubiquitin to substrate proteins determining their fate. One of the largest subfamilies of E3 ubiquitin ligases is the family of the tripartite motif (TRIM) proteins, whose dysregulation is associated with a variety of cellular processes and directly involved in human diseases and cancer. In this review we summarize the current knowledge and emerging concepts about TRIMs and their contribution to the correct regulation of cell cycle, describing how TRIMs control the cell cycle transition phases and their involvement in the different functional units of the mitotic process, along with implications in cancer progression.

scholarly journals Autophagy induced by SAHA affects mutant P53 degradation and cancer cell survival

2019 ◽  
Vol 39 (2) ◽  
Author(s):  
Giorgia Foggetti ◽  
Laura Ottaggio ◽  
Debora Russo ◽  
Carlotta Mazzitelli ◽  
Paola Monti ◽  
...  
Keyword(s):  
Cell Death ◽  
Human Cancer ◽  
Tp53 Gene ◽  
Mutant P53 ◽  
Strong Impact ◽  
Cancer Therapies ◽  
Missense Mutations ◽  
Reduce Cell Proliferation ◽  
Cancer Cell Survival ◽  
Autophagy Inhibition

Abstract Missense mutations in the TP53 gene produce mutant p53 (mutp53) proteins which may acquire oncogenic properties favoring chemoresistance, cell migration, and metastasis. The exploitation of cellular pathways that promote mutp53 degradation may reduce cell proliferation and invasion as well as increase the sensitivity to anticancer drugs, with a strong impact on current cancer therapies. In the last years, several molecules have been characterized for their ability to induce the degradation of mutp53 through the activation of autophagy. Here, we investigated the correlation between autophagy and mutp53 degradation induced by suberoylanilide hydroxamic acid (SAHA), an FDA-approved histone deacetylase inhibitor. In the human cancer lines MDA-MB-231 (mutp53-R280K) and DLD1 (mutp53-S241F), SAHA induced a significant mutp53 degradation. However, such degradation correlated with autophagy induction only in MDA-MB-231 cells, being counteracted by autophagy inhibition, which also increased SAHA-induced cell death. Conversely, in DLD1 cells SAHA triggered a low level of autophagy despite promoting a strong decrease in mutp53 level, and autophagy inhibition did not change either mutp53 levels or sensitivity to this drug. We conclude that autophagy can be a relevant pathway for mutp53 degradation induced by SAHA, but its contribution to mutp53 destabilization and the consequences on cell death are likely context-dependent.

Tumor Suppressor Microrna-29a/b and Microrna-34a Mediate Small Molecule PRIMA-1Met-Induced Aoptosis In Multiple Myeloma Cells By Targeting c-Myc

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1919-1919
Author(s):  
Manujendra N. Saha ◽  
Yijun Yang ◽  
Hong Chang
Keyword(s):  
Gene Expression ◽  
Cell Lines ◽  
Mutant P53 ◽  
Pcr Array ◽  
Wild Type ◽  
Down Regulation ◽  
Over Expression ◽  
P53 Status ◽  
Low Expression

Abstract PRIMA-1Met/APR246 (p53 reactivation and induction of massive apoptosis), is a small molecule with remarkable anti-tumor activities in various human tumor cells, and is currently under phase I/II clinical trial. We have previously demonstrated anti-tumor activity of PRIMA-1Met in multiple myeloma (MM) cells irrespective of p53 status. In addition, we have shown that PRIMA-1Met alone or in combination with dexamethasone triggers significant tumor growth inhibition in vivo in a murine xenograft model of human MM. However, the molecular mechanism underlying anti-myeloma activity of PRIMA-1Met has not been fully elucidated. MicroRNAs (miRNAs) are non-coding small RNA molecules that regulate post-transcriptional gene expression and play a critical role in tumor pathogenesis. Since the role of miRNAs and their regulation in response to PRIMA-1Met in MM is not known, here we investigated the relationship between PRIMA-1Met-induced apoptosis and miRNA expression in MM cells. Using a miRNA PCR array platform (Human Cancer Pathway Finder miScript miRNA PCR array, MIHS-102Z, Qiagen Inc), we analyzed the miRNA profiles in two MM cell lines of different p53 status (MM.1S with wild type p53 and 8226 with mutant p53) treated with either PRIMA-1Met or DMSO control. After normalization to a set of housekeeping genes, differential expressions of the miRNAs were analysed. miRNA-29a, miRNA-29b, and miRNA-34a were found significantly up-regulated (more than 2 fold, p<0.05) in cells treated with PRIMA-1Met compared to DMSO-treated cells. To evaluate the effect of over-expression of these miRNAs, we transfected two MM cell lines (MM.1S and 8226) with either miR-29a/b or miR-34a. Cells transfected with scramble miRNA were used as control. Over-expression of the miRNAs resulted in a dose-dependent inhibition of viability and increase in apoptosis of MM.1S or 8226 cells. Next, we examined the endogenous expression of these miRNAs in 5 primary MM samples by qPCR. Results showed a significant low expression of miR-29a/b and miR-34a in 3 of the 5 samples. Treatment of the two primary MM samples with low expression for miR-29a/b and miR-34a with PRIMA-1Met resulted in up-regulation of these miRNAs leading to inhibition of the viability and induction of apoptosis. To identify the possible targets of these miRNAs, we performed bioinformatics analysis. Results obtained from different searches by miRanda and TargetScan algorithm predicted c-Myc as a potential target for miRNA-29a/b and miRNA-34a. c-Myc is an oncogene whose over-expression has been associated with resistance to current chemotherapy in MM. Global gene expression profiling by microarray showed significant down-regulation of c-Myc in two MM cell lines with either wild type or mutant p53 treated with PRIMA-1Met compare to cells treated with DMSO. Importantly, down-regulation of c-Myc (∼2.6-fold) by PRIMA-1Met was also observed in a MM cell line (8226R5) lacking p53 expression suggesting an important role of c-Myc in p53-independent apoptosis of MM cells induced by PRIMA-1Met. By qPCR and Western blot analysis, we confirmed significant down-regulation of c-Myc in PRIMA-1Met-treated MM cells. These data provided the evidence for an inverse correlation between the expression of these miRNAs and c-Myc indicating that apoptosis of MM cells induced by PRIMA-1Met is regulated by miRNAs29a/b or miRNA34a targeting c-Myc. Our results suggest a novel mechanism for PRIMA-1Met-induced apoptotic signaling in MM cells mediated by up-regulation of miR-29a/b and miR-34a targeting c-Myc. Our findings also provide a preclinical framework for development of therapeutic strategies in combination of PRIMA-1Met and miRNA (miR-29a/b or miR-34a) mimics for the treatment of MM patients, especially for those with high c-Myc expressions. Disclosures: No relevant conflicts of interest to declare.

Increased expression of E3 ubiquitin ligases targeting p53 in CLL patients with wild-type TP53 exhibits associations with clinical features of the disease

2015 ◽  
Vol 57 (6) ◽  
pp. 1471-1473 ◽  
Author(s):  
Patryk Gorniak ◽  
Bozena Budziszewska ◽  
Bartosz Pula ◽  
Maja Wasylecka ◽  
Katarzyna Borg ◽  
...  
Keyword(s):  
Clinical Features ◽  
Ubiquitin Ligases ◽  
E3 Ubiquitin Ligases ◽  
Wild Type

scholarly journals A Family of Mammalian E3 Ubiquitin Ligases That Contain the UBR Box Motif and Recognize N-Degrons

2005 ◽  
Vol 25 (16) ◽  
pp. 7120-7136 ◽  
Author(s):  
Takafumi Tasaki ◽  
Lubbertus C. F. Mulder ◽  
Akihiro Iwamatsu ◽  
Min Jae Lee ◽  
Ilia V. Davydov ◽  
...  
Keyword(s):  
Sindbis Virus ◽  
Ubiquitin Ligases ◽  
Mammalian Genome ◽  
E3 Ubiquitin Ligases ◽  
Wild Type ◽  
Mouse Protein ◽  
Virus Rna ◽  
Early Embryos ◽  
Immunodeficiency Virus

ABSTRACT A subset of proteins targeted by the N-end rule pathway bear degradation signals called N-degrons, whose determinants include destabilizing N-terminal residues. Our previous work identified mouse UBR1 and UBR2 as E3 ubiquitin ligases that recognize N-degrons. Such E3s are called N-recognins. We report here that while double-mutant UBR1 −/− UBR2 −/− mice die as early embryos, the rescued UBR1 −/− UBR2 −/− fibroblasts still retain the N-end rule pathway, albeit of lower activity than that of wild-type fibroblasts. An affinity assay for proteins that bind to destabilizing N-terminal residues has identified, in addition to UBR1 and UBR2, a huge (570 kDa) mouse protein, termed UBR4, and also the 300-kDa UBR5, a previously characterized mammalian E3 known as EDD/hHYD. UBR1, UBR2, UBR4, and UBR5 shared a ∼70-amino-acid zinc finger-like domain termed the UBR box. The mammalian genome encodes at least seven UBR box-containing proteins, which we propose to call UBR1 to UBR7. UBR1 −/− UBR2 −/− fibroblasts that have been made deficient in UBR4 as well (through RNA interference) were significantly impaired in the degradation of N-end rule substrates such as the Sindbis virus RNA polymerase nsP4 (bearing N-terminal Tyr) and the human immunodeficiency virus type 1 integrase (bearing N-terminal Phe). Our results establish the UBR box family as a unique class of E3 proteins that recognize N-degrons or structurally related determinants for ubiquitin-dependent proteolysis and perhaps other processes as well.

scholarly journals Epithelial Mutant p53 Promotes Resistance to Anti-PD-1-Mediated Oral Cancer Immunoprevention in Carcinogen-Induced Mouse Models

Cancers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1471
Author(s):  
Jin Wang ◽  
Yuan Hu ◽  
Vicente Escamilla-Rivera ◽  
Cassandra L. Gonzalez ◽  
Lin Tang ◽  
...  
Keyword(s):  
Oral Cancer ◽  
Mouse Models ◽  
Cancer Progression ◽  
Mutant P53 ◽  
P53 Mutations ◽  
Loss Of Function ◽  
Wild Type ◽  
Oral Carcinogenesis ◽  
Wild Type P53 ◽  
Cancer Immunoprevention

Oral squamous cell carcinoma (OSCC) develops through the multistep malignant progression of squamous epithelium. This process can be prevented by PD-1 blockade in a mouse model for oral carcinogenesis. OSCCs exhibit a high incidence of p53 mutations that confer oncogenic gain-of-function (GOF) activities that promote resistance to standard therapies and poor clinical outcomes. To determine whether epithelial p53 mutations modulate anti-PD-1-mediated oral cancer immunoprevention, we generated mouse models for oral carcinogenesis by exposing mice carrying epithelial-specific p53 mutations to the carcinogen 4NQO. Consistent with the oncogenic functions of mutant p53, mice with OSCCs expressing the p53R172H GOF mutation developed higher metastasis rates than mice with loss-of-function (LOF) p53 deletion or with wild-type p53. Throughout oral cancer progression, pre-invasive and invasive lesions showed a gradual increase in T-cell infiltration, recruitment of immunosuppressive regulatory T-cells (Tregs), and induction of PD-1/PD-L1 immune checkpoint proteins. Notably, while PD-1 blockade prevented the development of OSCCs in mice with wild-type p53 or p53 deletion, GOF p53R172H abrogated the immunopreventive effects of anti-PD-1, associated with upregulation of IL17 signaling and depletion of exhausted CD8 cells in the microenvironment of the p53R172H tumors. These findings sustain a potential role for p53 profiling in personalized oral cancer immunoprevention.

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