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.

scholarly journals Modified Gold Nanoparticles to Overcome the Chemoresistance to Gemcitabine in Mutant p53 Cancer Cells

Pharmaceutics ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2067
Author(s):  
Eduardo García-Garrido ◽  
Marco Cordani ◽  
Álvaro Somoza
Keyword(s):  
Gold Nanoparticles ◽  
Cancer Cells ◽  
Electrostatic Interactions ◽  
Human Cancer ◽  
Tp53 Gene ◽  
Therapeutic Strategies ◽  
Mutant P53 ◽  
Layer By Layer ◽  
Missense Mutations ◽  
Efficient Delivery

Mutant p53 proteins result from missense mutations in the TP53 gene, the most mutated in human cancer, and have been described to contribute to cancer initiation and progression. Therapeutic strategies for targeting mutant p53 proteins in cancer cells are limited and have proved unsuitable for clinical application due to problems related to drug delivery and toxicity to healthy tissues. Therefore, the discovery of efficient and safe therapeutic strategies that specifically target mutant p53 remains challenging. In this study, we generated gold nanoparticles (AuNPs) chemically modified with low molecular branched polyethylenimine (bPEI) for the efficient delivery of gapmers targeting p53 mutant protein. The AuNPs formulation consists of a combination of polymeric mixed layer of polyethylene glycol (PEG) and PEI, and layer-by-layer assembly of bPEI through a sensitive linker. These nanoparticles can bind oligonucleotides through electrostatic interactions and release them in the presence of a reducing agent as glutathione. The nanostructures generated here provide a non-toxic and powerful system for the delivery of gapmers in cancer cells, which significantly downregulated mutant p53 proteins and altered molecular markers related to cell growth and apoptosis, thus overcoming chemoresistance to gemcitabine.

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 Identification of a druggable protein-protein interaction site between mutant p53 and its stabilizing chaperone DNAJA1

2020 ◽  
pp. jbc.RA120.014749
Author(s):  
Xin Tong ◽  
Dandan Xu ◽  
Rama K. Mishra ◽  
Ryan D Jones ◽  
Leyu Sun ◽  
...  
Keyword(s):  
Small Molecule ◽  
Tp53 Gene ◽  
Dominant Negative ◽  
Site Directed Mutagenesis ◽  
Dominant Negative Effect ◽  
Mutant P53 ◽  
Missense Mutations ◽  
Oncogenic Function

The TP53 gene is the most frequently mutated gene in human cancers, and the majority of TP53 mutations are missense mutations. As a result, these mutant p53 (mutp53) either directly lose wild-type p53 (wtp53) tumor suppressor function or exhibit a dominant negative effect over wtp53. In addition, some mutp53 have acquired new oncogenic function (gain of function). Therefore, targeting mutp53 for its degradation, may serve as a promising strategy for cancer prevention and therapy. Based on our previous finding that farnesylated DNAJA1 is a crucial chaperone in maintaining mutp53 stabilization, and by using an in silico approach, we built 3-D homology models of human DNAJA1 and mutp53R175H proteins, identified the interacting pocket in the DNAJA1-mutp53R175H complex, and found one critical druggable small molecule binding  site in the DNAJA1 glycine/phenylalanine rich region. We confirmed that the interacting pocket in the DNAJA1-mutp53R175H complex was crucial for stabilizing mutp53R175H using a site-directed mutagenesis approach. We further screened a drug-like library to identify a promising small molecule hit (GY1-22) against the interacting pocket in DNAJA1-mutp53R175H complex. The GY1-22 compound displayed an effective activity against DNAJA1-mutp53R175H complex. Treatment with GY1-22 significantly reduced mutp53 protein levels, enhanced Waf1p21 expression, suppressed cyclin D1 expression, and inhibited mutp53-driven pancreatic cancer growth both in vitro and in vivo. Together, our results indicate that the interacting pocket in the DNAJA1-mutp53R175H complex is critical for mutp53’s stability and oncogenic function, and DNAJA1 is a robust therapeutic target for developing the efficient small molecule inhibitors against oncogenic mutp53.

scholarly journals TP53 Mutation Status Influences Iron Regulatory Protein RNA Binding Activity and Sensitivity to Ferroptotic Cell Death

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1277-1277
Author(s):  
Laurie Thompson ◽  
Thais Oliveira ◽  
Evan Hermann ◽  
Mckale Montgomery ◽  
Winyoo Chowanadisai ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Viability ◽  
Tp53 Mutation ◽  
Rna Binding ◽  
Human Cancer ◽  
Regulatory Protein ◽  
Tp53 Gene ◽  
Binding Activity ◽  
Iron Regulatory Protein ◽  
Mutation Status

Abstract Objectives The tumor suppressor gene TP53 is the most commonly mutated gene in human cancer, but mutations in TP53 do not just result in loss of tumor suppressor function, they can also promote cancer progression by altering cellular iron acquisition and metabolism. A newly identified role for TP53 in the mediation of iron homeostasis and cancer cell survival lies in the ability for TP53 to protect against ferroptosis, a form of iron mediated cell death. The purpose of this study was to determine the extent to which TP53 mutation status effects iron-mediated cell death in response to ferroptosis induction. We also measured TP53 dependent differences in iron regulatory protein (IRP) RNA binding activity to begin to clarify the mechanisms by which TP53 mutation status may influence sensitivity to ferroptosis. Methods Using H1299 cells, which are null for TP53, we generated cell lines expressing either a tetracycline inducible wild-type TP53 gene, or a representative mutated TP53 gene from exemplary “hotspot” mutations in the DNA binding domain (R248, R273, R282, G245, R249 and R175). These six mutation types were selected because they represent 25% of all TP53 mutations in human cancer. To determine the influence of TP53 mutation status on sensitivity to ferroptotic cell death, we treated cells with erastin, a potent inducer of ferroptosis and measured differences in cell viability between these cell lines using PrestoBlue cell viability reagent. To assess mutant TP53-depenent differences in IRP RNA binding activity during ferroptosis we measured differences in IRP RNA binding activity via Electrophoretic Mobility-Shift Assay. Results We found that TP53 mutants (R273, R248, R175, G245, and R249) were significantly less viable (P < 0.05) after initiation of ferroptosis compared to cells expressing WT TP53. Following ferroptosis induction, we observed a significant (P < 0.05) increase in IRP RNA binding in G245, R248, and R175 mutants. Conclusions Our preliminary analyses indicate that TP53 mutants may be more sensitive to ferroptosis, but IRPs do not seem to be solely responsible for the increase in iron during ferroptotic cell death. Furthermore, ferroptosis may be a potential therapeutic target for cancers with these TP53 mutations but further investigation is warranted. Funding Sources Internal funding at Oklahoma State University.

scholarly journals Protein mimetic amyloid inhibitor potently abrogates cancer-associated mutant p53 aggregation and restores tumor suppressor function

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
L. Palanikumar ◽  
Laura Karpauskaite ◽  
Mohamed Al-Sayegh ◽  
Ibrahim Chehade ◽  
Maheen Alam ◽  
...  
Keyword(s):  
Self Assembly ◽  
Human Cancer ◽  
Mutant P53 ◽  
Amyloid Formation ◽  
Missense Mutations ◽  
Hydrophobic Core ◽  
Tumor Suppressor Function ◽  
Human Cancer Cells ◽  
Cycle Arrest ◽  
Bona Fide

AbstractMissense mutations in p53 are severely deleterious and occur in over 50% of all human cancers. The majority of these mutations are located in the inherently unstable DNA-binding domain (DBD), many of which destabilize the domain further and expose its aggregation-prone hydrophobic core, prompting self-assembly of mutant p53 into inactive cytosolic amyloid-like aggregates. Screening an oligopyridylamide library, previously shown to inhibit amyloid formation associated with Alzheimer’s disease and type II diabetes, identified a tripyridylamide, ADH-6, that abrogates self-assembly of the aggregation-nucleating subdomain of mutant p53 DBD. Moreover, ADH-6 targets and dissociates mutant p53 aggregates in human cancer cells, which restores p53’s transcriptional activity, leading to cell cycle arrest and apoptosis. Notably, ADH-6 treatment effectively shrinks xenografts harboring mutant p53, while exhibiting no toxicity to healthy tissue, thereby substantially prolonging survival. This study demonstrates the successful application of a bona fide small-molecule amyloid inhibitor as a potent anticancer agent.

scholarly journals Protein mimetic amyloid inhibitor potently abrogates cancer-associated mutant p53 aggregation and restores tumor suppressor function

2020 ◽  
Author(s):  
Loganathan Palanikumar ◽  
Laura Karpauskaite ◽  
Sarah Hassan ◽  
Maheen Alam ◽  
Mohamed Al-Sayegh ◽  
...  
Keyword(s):  
Self Assembly ◽  
Human Cancer ◽  
Mutant P53 ◽  
Amyloid Formation ◽  
Missense Mutations ◽  
Hydrophobic Core ◽  
Tumor Suppressor Function ◽  
Human Cancer Cells ◽  
Cycle Arrest ◽  
Bona Fide

ABSTRACTMissense mutations in p53 are severely deleterious and occur in over 50% of all human cancers. The vast majority of these mutations are located in the inherently unstable DNA-binding domain (DBD), many of which destabilize the domain further and expose its aggregation-prone hydrophobic core, prompting self-assembly of mutant p53 into inactive cytosolic amyloid-like aggregates. Screening an oligopyridylamide library, previously shown to inhibit amyloid formation associated with Alzheimer’s disease and type II diabetes, identified a tripyridylamide, ADH-6, that potently abrogates self-assembly of the aggregation-nucleating subdomain of mutant p53 DBD. Moreover, ADH-6 effectively targets and dissociates mutant p53 aggregates in human cancer cells, which restores p53’s transcriptional activity, leading to cell cycle arrest and apoptosis. Notably, ADH-6 treatment substantially shrinks xenografts harboring mutant p53 and prolongs survival, while exhibiting no toxicity to healthy tissue. This study demonstrates the first successful application of a bona fide small-molecule amyloid inhibitor as an anticancer agent.

scholarly journals Akt inhibition promotes autophagy and sensitizes PTEN-null tumors to lysosomotropic agents

2008 ◽  
Vol 183 (1) ◽  
pp. 101-116 ◽  
Author(s):  
Michael Degtyarev ◽  
Ann De Mazière ◽  
Christine Orr ◽  
Jie Lin ◽  
Brian B. Lee ◽  
...  
Keyword(s):  
Cell Death ◽  
Kinase Inhibitors ◽  
Human Cancer ◽  
Akt Pathway ◽  
Anticancer Efficacy ◽  
Human Cancer Cells ◽  
Cancer Cell Survival ◽  
Pathway Inhibition

Although Akt is known as a survival kinase, inhibitors of the phosphatidylinositol 3-kinase (PI3K)–Akt pathway do not always induce substantial apoptosis. We show that silencing Akt1 alone, or any combination of Akt isoforms, can suppress the growth of tumors established from phosphatase and tensin homologue–null human cancer cells. Although these findings indicate that Akt is essential for tumor maintenance, most tumors eventually rebound. Akt knockdown or inactivation with small molecule inhibitors did not induce significant apoptosis but rather markedly increased autophagy. Further treatment with the lysosomotropic agent chloroquine caused accumulation of abnormal autophagolysosomes and reactive oxygen species, leading to accelerated cell death in vitro and complete tumor remission in vivo. Cell death was also promoted when Akt inhibition was combined with the vacuolar H+–adenosine triphosphatase inhibitor bafilomycin A1 or with cathepsin inhibition. These results suggest that blocking lysosomal degradation can be detrimental to cancer cell survival when autophagy is activated, providing rationale for a new therapeutic approach to enhancing the anticancer efficacy of PI3K–Akt pathway inhibition.

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.

Inhibition of Autophagy Potentiated Hippocampal Cell Death Induced by Endoplasmic Reticulum Stress and its Activation by Trehalose Failed to be Neuroprotective

2019 ◽  
Vol 16 (1) ◽  
pp. 3-11
Author(s):  
Luisa Halbe ◽  
Abdelhaq Rami
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Cell Damage ◽  
Protective Mechanism ◽  
Unfolded Proteins ◽  
Neuronal Viability ◽  
Hippocampal Cell ◽  
Trigger Cell Death ◽  
Autophagy Inhibition

Introduction: Endoplasmic reticulum (ER) stress induced the mobilization of two protein breakdown routes, the proteasomal- and autophagy-associated degradation. During ERassociated degradation, unfolded ER proteins are translocated to the cytosol where they are cleaved by the proteasome. When the accumulation of misfolded or unfolded proteins excels the ER capacity, autophagy can be activated in order to undertake the degradative machinery and to attenuate the ER stress. Autophagy is a mechanism by which macromolecules and defective organelles are included in autophagosomes and delivered to lysosomes for degradation and recycling of bioenergetics substrate. Materials and Methods: Autophagy upon ER stress serves initially as a protective mechanism, however when the stress is more pronounced the autophagic response will trigger cell death. Because autophagy could function as a double edged sword in cell viability, we examined the effects autophagy modulation on ER stress-induced cell death in HT22 murine hippocampal neuronal cells. We investigated the effects of both autophagy-inhibition by 3-methyladenine (3-MA) and autophagy-activation by trehalose on ER-stress induced damage in hippocampal HT22 neurons. We evaluated the expression of ER stress- and autophagy-sensors as well as the neuronal viability. Results and Conclusion: Based on our findings, we conclude that under ER-stress conditions, inhibition of autophagy exacerbates cell damage and induction of autophagy by trehalose failed to be neuroprotective.

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