Novel Allosteric Mechanism of P53 Activation by Small Molecules for Targeted Anticancer Therapy

Novel allosteric mechanism of p53 activation by small molecules for targeted anticancer therapy

10.1101/384248 ◽

2018 ◽

Author(s):

Joanna Zawacka-Pankau ◽

Vera V. Grinkevich ◽

Mikhail Burmakin ◽

Aparna Vema ◽

Karin Fawkner ◽

...

Keyword(s):

Molecular Modeling ◽

Small Molecules ◽

Anticancer Therapy ◽

Mechanisms Of Action ◽

Allosteric Modulation ◽

Structural Element ◽

Allosteric Mechanism ◽

Anti Cancer ◽

P53 Activation ◽

Pharmacological Potential

AbstractGiven the immense significance of p53 restoration for anti-cancer therapy, elucidation of the mechanisms of action of p53-activating molecules is of the utmost importance. Here we report a discovery of novel allosteric modulation of p53 by small molecules, which is an unexpected turn in the p53 story. We identified a structural element involved in p53 regulation, whose targeting by RITA, PpIX and licofelone block the binding of p53 inhibitors, MDM2 and MDMX. Deletion and mutation analysis followed by molecular modeling, identified the key p53 residues S33 and S37 targeted by RITA and PpIX. We propose that the binding of small molecules to the identified site induces a conformational trap preventing p53 from the interaction with MDM2 and MDMX. These results point to a high potential of allosteric activators. Our study provides the basis for the development of therapeutics with a novel mechanism of action, thus extending the p53 pharmacological potential.

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Minimal mechanistic component of proteasome activation and prevention of impairment by pathological oligomers

10.21203/rs.3.rs-900719/v1 ◽

2021 ◽

Author(s):

Janelle Chuah ◽

Tifffany Thibaudeau ◽

David Smith

Keyword(s):

Small Molecules ◽

Conformational Changes ◽

Bound State ◽

Proof Of Concept ◽

Α Subunit ◽

Gate Opening ◽

Allosteric Mechanism ◽

Dependent Mechanism ◽

Degradation Of Peptides

Abstract Impairment of proteasomal function has been implicated in neurodegenerative diseases, justifying the need to understand how the proteasome is activated for protein degradation. Here, using biochemical and structural (cryo-EM) strategies in both archaeal and mammalian proteasomes, we further determine the HbYX(-motif)-dependent mechanism of proteasomal activation used by multiple proteasome-activating complexes including the 19S Particle. We identify multiple proteasome α subunit residues involved in HbYX-dependent activation, a point mutation that activates the proteasome by partially mimicking a HbYX-bound state, and conformational changes involved in gate-opening with a 2.0A structure. Through an iterative process of peptide synthesis, we successfully design a HbYX-like dipeptide mimetic as a robust tool to elucidate how the motif autonomously activates the proteasome. The mimetic induces near complete gate-opening at saturating concentration, activating mammalian proteasomal degradation of peptides and proteins. Findings using our peptide mimetic suggest the HbYX-dependent mechanism requires cooperative binding in at least two intersubunit pockets of the α ring. Collectively, the results presented here unambiguously demonstrate the lone role of the HbYX tyrosine in the allosteric mechanism of proteasome activation and offer proof of concept for the robust potential of HbYX-like small molecules to activate the proteasome.

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TRAIN (Transcription of Repeats Activates INterferon) in response to chromatin destabilization induced by small molecules in mammalian cells

eLife ◽

10.7554/elife.30842 ◽

2018 ◽

Vol 7 ◽

Cited By ~ 10

Author(s):

Katerina Leonova ◽

Alfiya Safina ◽

Elimelech Nesher ◽

Poorva Sandlesh ◽

Rachel Pratt ◽

...

Keyword(s):

Small Molecules ◽

Mammalian Cells ◽

Genomic Stability ◽

Cellular Responses ◽

Dna Demethylation ◽

Interferon Response ◽

Dependent Manner ◽

Dna Interactions ◽

P53 Activation ◽

Nf Kappab

Cellular responses to the loss of genomic stability are well-established, while how mammalian cells respond to chromatin destabilization is largely unknown. We previously found that DNA demethylation on p53-deficient background leads to transcription of repetitive heterochromatin elements, followed by an interferon response, a phenomenon we named TRAIN (Transcription of Repeats Activates INterferon). Here, we report that curaxin, an anticancer small molecule, destabilizing nucleosomes via disruption of histone/DNA interactions, also induces TRAIN. Furthermore, curaxin inhibits oncogene-induced transformation and tumor growth in mice in an interferon-dependent manner, suggesting that anticancer activity of curaxin, previously attributed to p53-activation and NF-kappaB-inhibition, may also involve induction of interferon response to epigenetic derepression of the cellular ‘repeatome’. Moreover, we observed that another type of drugs decondensing chromatin, HDAC inhibitor, also induces TRAIN. Thus, we proposed that TRAIN may be one of the mechanisms ensuring epigenetic integrity of mammalian cells via elimination of cells with desilenced chromatin.

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p53 Activation by Small Molecules: Application in Oncology

ChemInform ◽

10.1002/chin.200540269 ◽

2005 ◽

Vol 36 (40) ◽

Author(s):

Lyubomir T. Vassilev

Keyword(s):

Small Molecules ◽

P53 Activation

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Targeting the Oncoprotein Smoothened by Small Molecules: Focus on Novel Acylguanidine Derivatives as Potent Smoothened Inhibitors

Cells ◽

10.3390/cells7120272 ◽

2018 ◽

Vol 7 (12) ◽

pp. 272 ◽

Cited By ~ 14

Author(s):

Silvia Pietrobono ◽

Barbara Stecca

Keyword(s):

Small Molecules ◽

Anticancer Therapy ◽

Clinical Settings ◽

Clinical Use ◽

Mechanisms Of Resistance ◽

Tumor Initiating Cells ◽

Promising Therapeutic Target ◽

Gli Transcription Factors ◽

Cancer Types ◽

Hh Signaling

Hedgehog-GLI (HH) signaling was originally identified as a critical morphogenetic pathway in embryonic development. Since its discovery, a multitude of studies have reported that HH signaling also plays key roles in a variety of cancer types and in maintaining tumor-initiating cells. Smoothened (SMO) is the main transducer of HH signaling, and in the last few years, it has emerged as a promising therapeutic target for anticancer therapy. Although vismodegib and sonidegib have demonstrated effectiveness for the treatment of basal cell carcinoma (BCC), their clinical use has been hampered by severe side effects, low selectivity against cancer stem cells, and the onset of mutation-driven drug resistance. Moreover, SMO antagonists are not effective in cancers where HH activation is due to mutations of pathway components downstream of SMO, or in the case of noncanonical, SMO-independent activation of the GLI transcription factors, the final mediators of HH signaling. Here, we review the current and rapidly expanding field of SMO small-molecule inhibitors in experimental and clinical settings, focusing on a class of acylguanidine derivatives. We also discuss various aspects of SMO, including mechanisms of resistance to SMO antagonists.

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Expression of JAZ in Multiple Myeloma and Its Potential Role as A Novel Molecular Target.

Blood ◽

10.1182/blood.v114.22.2862.2862 ◽

2009 ◽

Vol 114 (22) ◽

pp. 2862-2862

Author(s):

Mingli Yang ◽

Jingxin Qiu ◽

Ying Li ◽

David Ostrov ◽

Jinghua Jia ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Cell Death ◽

Small Molecules ◽

Normal Tissue ◽

Potential Role ◽

Plasma Cells ◽

Hematologic Malignancies ◽

Molecular Target ◽

P53 Activation

Abstract Abstract 2862 Poster Board II-838 Multiple myeloma (MM) is an incurable hematologic tumor caused by malignant transformation of plasma cells. JAZ (just another zinc finger protein) was previously identified in our laboratory as a unique ZFP that preferentially binds to double-stranded (ds) RNA rather than dsDNA. The JAZ gene is localized to the human chromosome 5q35-ter, which is a specific chromosomal region at which deletions and translocations occur in different hematologic malignancies including multiple myeloma. The NCI Cancer Genome Anatomy Project data base search reveals that a validated SNP (single nucleotide polymorphism) exists for JAZ at an evolutionarily conserved, 3'-untranslated, regulatory region of JAZ mRNA. This specific SNP exists only in the bone marrow cancer but not in the normal tissue, suggesting a potential role for JAZ in hematologic malignancies. Importantly, we recently discovered JAZ as a novel direct, positive regulator of p53 transcriptional activity. The mechanism involves direct binding to p53's C-terminal (negative) regulatory domain to activate “latent” p53 in response to non-genotoxic stress signals. Moreover, we found that interleukin-3 growth factor withdrawal upregulates JAZ expression in factor-dependent hematopoietic cells in association with activation of the p53 tumor suppressor and induction of apoptotic cell death, indicating that the expression of JAZ is important in the stress response. Thus, to examine the role of JAZ expression in hematologic malignancies, we carried out an immunohistochemistry (IHC) study of JAZ expression in murine and human bone marrow cells and in normal and malignant hematologic tissues and cell lines. The affinity-purified rabbit polyclonal antibody JAZ111 was used and its specificity was verified by the peptide inhibition and also using a commercially available monoclonal antibody against JAZ. Results reveal that JAZ is differentially expressed in different types or stages of hematopoietic cells. For instance, morphologically, JAZ appears to be (relatively) abundantly expressed in plasma cells in normal bone marrow samples and such observation was verified by co-staining with a CD38 antibody. Interestingly, results of JAZ111 staining of an MM tissue microarray (24 cases/48 cores, 13 MM and 11 normal tissues) reveal that in ∼50 % of the MM samples the expression of JAZ is substantially down-regulated compared to the normal tissue controls. This supports the notion that JAZ may play a tumor suppressor role. However, there are exceptions that JAZ was found to be highly or over-expressed in some MM samples on the microarray and other regular individual sample slides, suggesting that JAZ may be latent or inactivated in these cases. Co-staining of the MM samples with a p53 antibody shows that expression of p53 is low, which agrees with the notion that p53 expressed in the MM samples is usually the wild type but in a latent state since the p53 gene has been reported to be rarely mutated and the p53 pathway remains intact in multiple myeloma. Thus, we hypothesize that activation or reactivation of JAZ in the MM cells which express abundant but latent JAZ may induce p53 activation to arrest or kill MM cells. We have explored JAZ as a potentially novel molecular target in multiple myeloma by identifying small molecules that bind and activate JAZ. Using a high-throughput, “molecular docking” strategy, we have screened approximately 240,000 small molecules for their ability to interact with JAZ. Based on the Lipinski Rules for Drug Likeness (molecular characteristics favorable for absorption and permeability), we identified ∼70 putative “drug-like” binding molecules with high scores and obtained ∼40 of them from the NCI Developmental Therapeutics Program. We performed the cell viability study, flow cytometry and Western blot analysis to test their effect on the MM cell lines. Results demonstrate that several of the “candidate” JAZ-targeting compounds can potently induce growth arrest and/or cell death in association with p53 activation. Therefore, while further in vitro and in vivo characterization remains to be carried out, the JAZ-“targeting” compounds point the way to develop a potentially novel therapeutic strategy targeting JAZ to treat multiple myeloma. Disclosures: No relevant conflicts of interest to declare.

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New developments in small molecules targeting p53 pathways in anticancer therapy

Drug Development Research ◽

10.1002/ddr.20261 ◽

2008 ◽

Vol 69 (6) ◽

pp. 289-296 ◽

Cited By ~ 6

Author(s):

Chit Fang Cheok ◽

David P. Lane

Keyword(s):

Small Molecules ◽

Anticancer Therapy ◽

New Developments

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Inhibition of the Eukaryotic 80S Ribosome as a Potential Anticancer Therapy: A Structural Perspective

Cancers ◽

10.3390/cancers13174392 ◽

2021 ◽

Vol 13 (17) ◽

pp. 4392

Author(s):

Simone Pellegrino ◽

Salvatore Terrosu ◽

Gulnara Yusupova ◽

Marat Yusupov

Keyword(s):

Cell Growth ◽

Small Molecules ◽

Cancer Cells ◽

Messenger Rna ◽

Protein Biosynthesis ◽

Structural Data ◽

Anticancer Therapy ◽

80S Ribosome ◽

Molecular Bases ◽

Major Target

Protein biosynthesis is a vital process for all kingdoms of life. The ribosome is the massive ribonucleoprotein machinery that reads the genetic code, in the form of messenger RNA (mRNA), to produce proteins. The mechanism of translation is tightly regulated to ensure that cell growth is well sustained. Because of the central role fulfilled by the ribosome, it is not surprising that halting its function can be detrimental and incompatible with life. In bacteria, the ribosome is a major target of inhibitors, as demonstrated by the high number of small molecules identified to bind to it. In eukaryotes, the design of ribosome inhibitors may be used as a therapy to treat cancer cells, which exhibit higher proliferation rates compared to healthy ones. Exciting experimental achievements gathered during the last few years confirmed that the ribosome indeed represents a relevant platform for the development of anticancer drugs. We provide herein an overview of the latest structural data that helped to unveil the molecular bases of inhibition of the eukaryotic ribosome triggered by small molecules.

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