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Surface plasmon resonance and cytotoxicity assays of drug efficacies predicted computationally to inhibit p53/MDM2 interaction.

ABSTRACT: Docking on the p53-binding site of murine double minute 2 (MDM2) by small molecules restores p53's tumor-suppressor function. We previously assessed 3244 FDA-approved drugs via "computational conformer selection" for inhibiting MDM2 and p53 interaction. Here, we developed a surface plasmon resonance method to experimentally confirm the inhibitory effects of the known MDM2 inhibitor, nutlin-3a, and two drug candidates predicted by our computational method. This p53/MDM2 interaction displayed a dosage-dependent weakening when MDM2 is pre-mixed with drug candidates. The inhibition efficiency order is nutlin-3a (IC50?=?97?nM)?>?bepridil (206?nM)?>?azelastine (307?nM). Furthermore, we verified their anti-proliferation effects on SJSA-1 (wild-type p53 and overexpressed MDM2), SW480 (mutated p53), and SaOs-2 (deleted p53) cancer cell lines. The inhibitory order towards SJSA-1?cell line is nutlin-3a (IC50?=?0.8??M)?>?bepridil (23??M)?>?azelastine (25??M). Our experimental results are in line with the computational prediction, and the higher IC50 values from the cell-based assays are due to the requirement of higher drug concentrations to penetrate cell membranes. The anti-proliferation effects of bepridil and azelastine on the cell lines with mutated and deleted p53 implied some p53-independent anti-proliferation effects.

SUBMITTER: Wang X

PROVIDER: S-EPMC6942878 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Surface plasmon resonance and cytotoxicity assays of drug efficacies predicted computationally to inhibit p53/MDM2 interaction.

Wang Xiaoying X Magdziarz Patrycja P Enriquez Ernest E Zhao Wang W Quan Chris C Darabedian Narek N Momand Jamil J Zhou Feimeng F

Analytical biochemistry 20190202

Docking on the p53-binding site of murine double minute 2 (MDM2) by small molecules restores p53's tumor-suppressor function. We previously assessed 3244 FDA-approved drugs via "computational conformer selection" for inhibiting MDM2 and p53 interaction. Here, we developed a surface plasmon resonance method to experimentally confirm the inhibitory effects of the known MDM2 inhibitor, nutlin-3a, and two drug candidates predicted by our computational method. This p53/MDM2 interaction displayed a do ...[more]

PMID: 30721669

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Project description:BACKGROUND:Inactivation of the tumor suppressor p53 is critical for pathogenesis of glioma, in particular glioblastoma multiforme (GBM). MDM2, the main negative regulator of p53, binds to and forms a stable complex with p53 to regulate its activity. Hitherto, it is unclear whether the stability of the p53/MDM2 complex is affected by lncRNAs, in particular circular RNAs that are usually abundant and conserved, and frequently implicated in different oncogenic processes. METHODS:RIP-seq and RIP-qPCR assays were performed to determine the most enriched lncRNAs (including circular RNAs) bound by p53, followed by bioinformatic assays to estimate the relevance of their expression with p53 signaling and gliomagenesis. Subsequently, the clinical significance of CDR1as was evaluated in the largest cohort of Chinese glioma patients from CGGA (n?=?325), and its expression in human glioma tissues was further evaluated by RNA FISH and RT-qPCR, respectively. Assays combining RNA FISH with protein immunofluorescence were performed to determine co-localization of CDR1as and p53, followed by CHIRP assays to confirm RNA-protein interaction. Immunoblot assays were carried out to evaluate protein expression, p53/MDM2 interaction and p53 ubiquitination in cells in which CDR1as expression was manipulated. After AGO2 or Dicer was knocked-down to inhibit miRNA biogenesis, effects of CDR1as on p53 expression, stability and activity were determined by immunoblot, RT-qPCR and luciferase reporter assays. Meanwhile, impacts of CDR1as on DNA damage were evaluated by flow cytometric assays and immunohistochemistry. Tumorigenicity assays were performed to determine the effects of CDR1as on colony formation, cell proliferation, the cell cycle and apoptosis (in vitro), and on tumor volume/weight and survival of nude mice xenografted with GBM cells (in vivo). RESULTS:CDR1as is found to bind to p53 protein. CDR1as expression decreases with increasing glioma grade and it is a reliable independent predictor of overall survival in glioma, particularly in GBM. Through a mechanism independent of acting as a miRNA sponge, CDR1as stabilizes p53 protein by preventing it from ubiquitination. CDR1as directly interacts with the p53 DBD domain that is essential for MDM2 binding, thus disrupting the p53/MDM2 complex formation. Induced upon DNA damage, CDR1as may preserve p53 function and protect cells from DNA damage. Significantly, CDR1as inhibits tumor growth in vitro and in vivo, but has little impact in cells where p53 is absent or mutated. CONCLUSIONS:Rather than acting as a miRNA sponge, CDR1as functions as a tumor suppressor through binding directly to p53 at its DBD region to restrict MDM2 interaction. Thus, CDR1as binding disrupts the p53/MDM2 complex to prevent p53 from ubiquitination and degradation. CDR1as may also sense DNA damage signals and form a protective complex with p53 to preserve p53 function. Therefore, CDR1as depletion may play a potent role in promoting tumorigenesis through down-regulating p53 expression in glioma. Our results broaden further our understanding of the roles and mechanism of action of circular RNAs in general and CDR1as in particular, and can potentially open up novel therapeutic avenues for effective glioma treatment.

Project description:Human milk glycans inhibit binding between norovirus and its host glycan receptor; such competitive inhibition by human milk glycans is associated with a reduced risk of infection. The relationship between the presence of specific structural motifs in the human milk glycan and its ability to inhibit binding by specific norovirus strains requires facile, accurate and miniaturized-binding assays. Toward this end, a high-throughput biosensor platform was developed based on surface plasmon resonance imaging (SPRi) of glycan microarrays. The SPRi was validated, and its utility was tested, by measuring binding specificities between defined human milk glycan epitopes and the capsids of two common norovirus strains, VA387 and Norwalk. Human milk oligosaccharide (HMOS)-based neoglycoconjugates, including chemically derived neoglycoproteins and oligosaccharide-glycine derivatives, were used to represent polyvalent glycoconjugates and monovalent oligosaccharides, respectively, in human milk. SPRi binding results established that the glycan motifs that bind norovirus capsids depend upon strain; VA387 capsid interacts with two neoglycoproteins, whereas Norwalk capsid binds to a different set of HMOS motifs in the form of both polyvalent neoglycoproteins and monovalent oligosaccharides. SPRi competitive binding assays further demonstrated that specific norovirus-binding glycans are able to inhibit norovirus capsid binding to their host receptors. A polyvalent neoglycoconjugate with clustered carbohydrate moieties is required for the inhibition of VA387 capsid binding to host receptor glycans, whereas both monovalent oligosaccharides and polyvalent neoglycoconjugates are able to inhibit Norwalk capsid binding to its host receptor. Binding of HMOS and HMOS-based neoglycoconjugates to norovirus capsids depends upon the specific strain characteristics, implying that HMOS and their polyvalent derivatives are potential anti-adhesive agents for norovirus prophylaxis.

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Surface plasmon resonance and cytotoxicity assays of drug efficacies predicted computationally to inhibit p53/MDM2 interaction.

Publications

Surface plasmon resonance and cytotoxicity assays of drug efficacies predicted computationally to inhibit p53/MDM2 interaction.

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