Inhibitors Of MDM2-p53 Interaction Research Articles

Abstract LB413: A newly developed patient-derived culture panel identifies precision therapies and pan-effective agents for head and neck squamous cell carcinoma

Abstract Head and neck squamous carcinoma (HNSCC) is an aggressive cancer with few treatment options. Its well-known genetic heterogeneity presents a major challenge for precision medicine development. We report a newly developed panel of 20 HNSCC patient-derived cultures (HNSCC-PDCs) from advanced or recurrent HNSCC, with comprehensive somatic and germline characterization for precision medicine (PM) discovery. The PDCs retain genetic heterogeneity of the original patient tumors, and xenografts of which also phenocopied HNSCC patient tumors. Importantly, somatic and germline events that were never or seldom captured by long-established HNSCC cell lines are represented by the PDC panel, including HRAS-CASP8 co-mutations, EGFR-AS1 germline mutation, exonic germline PIK3CA mutation, sonic hedgehog (SHH) pathway and FGFR pathway mutations. We hypothesize that drug screening with this newly developed HNSCC-PDC panel that recapitulates HNSCC patient genetics may identify new gene-drug sensitivity relationships for precision medicine development in advanced HNSCC. Here, data from our pilot drug screen of 38 selected FDA approved/Phase I-II clinical trial agents first reveal: 1) HNSCC-PDC with the hotspot HRASp.G13R, together with CASP8p.L183S, is sensitive to tipifarnib vs. tipifarnib-resistance in a long-established HNSCC cell line, SNU899 with the same HRAS mutation. Subsequent high-content imaging cell death assay further demonstrates a dose-dependent tipifarnib-induced cell death in HRASp.G13R-mutated PDC, but not in SNU-899; 2) TP53-EP300 co-mutated HNSCC-PDCs are most sensitive to cisplatin with ~340 nM sensitivity (mean IC50) among all PDCs tested, which is 22 times more sensitive than that reported in Genomics of Drug Sensitivity in Cancer (GDSC) HNSCC cell lines; 3) EGFR-AS1 (c.2361G>A)-germline mutated PDCs, and MAPK1-mutated PDCs, are both hypersensitive to EGFR inhibitors (EGFRi: erlotinib and mobocertinib), which independently credentialed gene-drug sensitivity relationships reported in exceptional responders in HNSCC clinical trials. Further signaling investigation in PDC models demonstrates phospho-MAPK activation as a reliable surrogate biomarker for EGFRi sensitivity in HNSCC; 4) FRS3-mutated PDCs are sensitive to FDA-approved FGFR pathway inhibitors; and 5) TP53-wildtype HNSCC-PDCs are 150-fold more sensitive to novel p53-MDM2 interaction inhibitors vs. TP53-mutated PDCs, a phenomenon that cannot be captured in long-established TP53-wildtype HNSCC cell lines. Lastly, 4 pan-PDC effective agents are identified with nM sensitivities and high drug activities (i.e. drug-induced growth inhibition) in more than half of our PDC models. These include 3 FDA-approved agents, TAK-981, Selinexor (a novel XPO1 inhibitor), and trametinib, as well as the preclinical agent JQ1. In conclusion, our pilot HNSCC-PDC drug screen identifies new gene-drug sensitivity relationships for HNSCC PM development and new pan-effective agents for advanced HNSCC. Citation Format: Yuen Keng Ng, Hui Li, Wenying Piao, Cecilia Pik Yuk Lau, Peony Hiu Yan Poon, Tin Yu Samuel Law, Jason Ying Kuen Chan, Yuxiong Su, Chin Wang Lau, Zigui Chen, Laura Ren Huey Ip, Thomas Chung-Kit Yeung, Sai Fung Yeung, Jason Hoi-Lam Ngan, Zoey Wing Yee Liu, Noah R. Wiese, Vivie Vo, Zoey Patel, Jeremia Onyekachi, Laili Afzali, Jasmine Zohal Afzali, Jack Nimitz Smith, Vivian Wai Yan Lui. A newly developed patient-derived culture panel identifies precision therapies and pan-effective agents for head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB413.

Abstract 666: ASTX295 engages p53-mediated apoptosis and an inflammatory response in patient derived mesothelioma explants

Abstract Mesothelioma is a universally lethal, rare cancer caused by asbestos that is lacking effective targeted treatments, particularly in the relapsed setting. P53 is predominantly wildtype (WT 83%) but is likely restrained by MDM2 particularly in the context of 9p21 deletion, a common, clonal somatic event affecting around half of all mesotheliomas that results in deletion of the MDM2 suppressor ARF. 9p21 deletion is also associated with a cold, immunosuppressed microenvironment. Unleashing p53WT by inhibiting its interaction with MDM2 has therapeutic potential in mesothelioma. To test this hypothesis, we employed live patient derived explants (PDEs) as a model that reflects the genomic inter-patient heterogeneity of mesotheliomas, and harbours an intact tumour microenvironment. Between August 2017 and April 2021 a total of 71 patients were consented prior to extended pleurectomy decortication, and PDEs were harvested at the time of surgery. PDEs were then cultured and treated with ASTX295, an inhibitor of p53-MDM2 interaction, using two concentrations (0.5 and 1 micromolar) and two timepoints (48 and 72 hours). PDEs passing quality control were subjected to spatial profiling using multiplex immunofluorescence microscopy. PDEs harbouring p53WT showed ASTX295-induced p21 (CDK1A) upregulation, which correlated with induction of apoptosis (p=0.04). PDE rank-order sensitivity was conserved across different doses and exposure-times. Transcriptome analysis confirmed ASTX295 induced p53 pathway activation in conjunction with a pro-inflammatory phenotype; both of which were absent in one PDE harbouring an inactivating p53 single nucleotide variant. Constitutive epithelial mesenchymal transition (EMT) was enriched in responding PDEs, as well as MDM2 inhibitor sensitive mesothelioma cell lines. 9p21 deletion (revealed by exome sequencing) was detected in both responding and non-responding PDEs. In summary, inhibition of MDM2-P53 interaction triggers robust p53 activation and a pro-inflammatory phenotype, which is potentiated in EMT enriched mesothelioma PDEs. ASTX295 is currently under clinical investigation (NCT03975387). Citation Format: Dean Anthony Fennell, Joanna Dzialo, Jan Rogel, Daniel Faulkner, Nada Nusrat, Aleksandra Bzura, Kudzayi Kutywayo, Peter Wells-Jordan, Charlotte Poile, Andrea Biondo, Martin Sims, Apostolos Nakas, Jin-Li Luo, Min Zhang, Maria Ahn. ASTX295 engages p53-mediated apoptosis and an inflammatory response in patient derived mesothelioma explants [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 666.

Abstract 7193: ABCB1-mediated chemotherapeutic drug resistance is reversed by a potent p53-MDM2 inhibitor NVP-HDM201

Abstract The failure of chemotherapy in cancer persists as a result of overexpression of various ATP-binding cassette (ABC) transporters. ABCB1 is one such transporter that actively pumps out chemotherapeutic drugs and it is one of the reasons for multidrug resistance (MDR). In the last few years, activation of p53 has been targeted as a therapeutic strategy in the treatment of cancers. Siremadlin (NVP-HDM201) is a potent and selective inhibitor of p53-MDM2 interaction. The objective of this study was to explore the ability of HDM201 to reverse tumor MDR attributable to overexpression of ABC transporters. According to our findings, HDM201 significantly increased the sensitivity of ABCB1-overexpressing cells to ABCB1 substrates, such as colchicine and doxorubicin. We found that HDM201 reverses ABCB1-mediated MDR by interacting with ABCB1 and blocking its function without affecting the expression and cellular localization of ABCB1. Moreover, HDM201 promoted the accumulation of paclitaxel in cell lines that overexpress ABCB1. At both high and low doses, HDM201 increased the ATPase activity of ABCB1. The computational support for the cross-reactivity of this p53 inhibitor with human ABCB1 comes from docking simulation results that align with the binding conformation of HDM201 within the vast cavity of the transmembrane region of ABCB1. In conclusion, by blocking the transport function of ABCB1, HDM201 can reverse ABCB1-mediated MDR in vitro. Citation Format: Harsh Patel, Chaoyun Cai, Zhuoxun Wu, Qiuxu Teng, Hanli Li, Zhe-Sheng Chen. ABCB1-mediated chemotherapeutic drug resistance is reversed by a potent p53-MDM2 inhibitor NVP-HDM201 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7193.

Structure-Activity Relationship Studies of Chalcones and Diarylpentanoids with Antitumor Activity: Potency and Selectivity Optimization.

We previously reported that chalcone CM-M345 (1) and diarylpentanoid BP-C4 (2) induced p53-dependent growth inhibitory activity in human cancer cells. Herein, CM-M345 (1) and BP-C4 (2) analogues were designed and synthesized in order to obtain more potent and selective compounds. Compounds 16, 17, 19, 20, and 22-24 caused pronounced in vitro growth inhibitory activity in HCT116 cells (0.09 < GI50 < 3.10 μM). Chemical optimization of CM-M345 (1) led to the identification of compound 36 with increased selectivity for HCT116 cells expressing wild-type p53 compared to its p53-null isogenic derivative and low toxicity to non-tumor HFF-1 cells. The molecular modification of BP-C4 (2) resulted in the discovery of compound 16 with more pronounced antiproliferative activity and being selective for HCT116 cells with p53, as well as 17 with enhanced antiproliferative activity against HCT116 cells and low toxicity to non-tumor cells. Compound 16 behaved as an inhibitor of p53-MDM2 interaction, and compound 17 was shown to induce apoptosis, associated with an increase in cleaved PARP and decreased levels of the anti-apoptotic protein Bcl-2. In silico studies allowed us to predict the druglikeness and ADMET properties for 16 and 17. Docking and molecular dynamics studies predicted that 16 could bind stably to the MDM2 binding pocket.

MDM2 antagonists promote CRISPR/Cas9-mediated precise genome editing in sheep primary cells

CRISPR-Cas9-mediated genome editing in sheep is of great use in both agricultural and biomedical applications. While targeted gene knockout by CRISPR-Cas9 through non-homologous end joining (NHEJ) has worked efficiently, the knockin efficiency via homology-directed repair (HDR) remains lower, which severely hampers the application of precise genome editing in sheep. Here, in sheep fetal fibroblasts (SFFs), we optimized several key parameters that affect HDR, including homology arm (HA) length and the amount of double-stranded DNA (dsDNA) repair template; we also observed synchronization of SFFs in G2/M phase could increase HDR efficiency. Besides, we identified three potent small molecules, RITA, Nutlin3, and CTX1, inhibitors of p53-MDM2 interaction, that caused activation of the p53 pathway, resulting in distinct G2/M cell-cycle arrest in response to DNA damage and improved CRISPR-Cas9-mediated HDR efficiency by 1.43- to 4.28-fold in SFFs. Furthermore, we demonstrated that genetic knockout of p53 could inhibit HDR in SFFs by suppressing the expression of several key factors involved in the HDR pathway, such as BRCA1 and RAD51. Overall, this study offersan optimized strategy for the usage of dsDNA repair template, more importantly, the application of MDM2 antagonists provides a simple and efficient strategy to promote CRISPR/Cas9-mediated precise genome editing in sheep primary cells.

Effect of Nutlin-3a on stability of p53-MDM2 complex

&lt;sec&gt;P53 is well recognized to be a tumor suppressor protein. In response to the external stress or environmental perturbation, p53 can promote the transcription of various target genes downstream, thus regulating the cell cycle, apoptosis, DNA repair, and angiogenesis. However, the activation of p53 is further activated by another protein, MDM2, which negatively regulates the level of p53 inverse and thus reduces the activation of p53. This phenomenon is a novel potential and promising strategy for cancer therapy, i.e. restoring the activity of p53 pathway through the competitive inhibitors that can occupy the p53-binding site of MDM2 and thus inhibit the interaction between p53 and MDM2.&lt;/sec&gt;&lt;sec&gt;Recently, various kinds of the inhibitors have been designed for this purpose. The Nutlin family is a group of well investigated inhibitors, which shows high efficiency for tumor suppression. Nutlin-3a mimics the MDM2-binding site of p53 essentially, and blocks the binding of MDM2 to p53. Once getting free from MDM2, p53 rapidly accumulates in the nuclei of cancer cells, the p53 target genes and the p53 pathway are activated, thereby resulting in cell-cycle arrest and apoptosis. In our previous papers, we investigated the competition mechanism between Nutlin3 and p53 &lt;i&gt;in vitro&lt;/i&gt; by using molecular dynamics simulations. We found that Nutlin3 can bind faster than p53 to prevent p53 from binding to MDM2 when Nutlin-3a and p53 have equal distance from MDM2. Nutlin-3a can also bind to the p53-MDM2 complex to disturb and weaken the interactions between p53 and MDM2. However, the underlying mechanisms of p53-MDM2 complex instability &lt;i&gt;in vivo&lt;/i&gt; are still unclear. And these inhibitors also have a variety of specificities and biological toxicities &lt;i&gt;in vivo&lt;/i&gt; environment.&lt;/sec&gt;&lt;sec&gt;In this study, we go a further step to investigate the effect of Nutlin-3a on the stability of p53-MDM2 complex in physiological environment with the aid of the molecular mechanics/generalized borne surface area (MM/GBSA) method. In our simulations, a group of Nutlin-3a molecules are randomly put around the p53 binding pocket of MDM2 in the initial stages to examine the dynamics among p53, MDM2 and the group of Nutlin-3a molecules and to analyze the underlying competition mechanism between Nutlin3 and p53 binding to pocket of MDM2.&lt;/sec&gt;&lt;sec&gt;We find that Nutlin-3a can induce the centroid distance between p53 and MDM2 to increase. Importantly, we show that Nutlin-3a weakens the binding affinity of p53-MDM2 complex. Consistently, Nutlin-3a breaks a hydrogen bond between Phe19-Gln72 and a salt bridge between Glu17-Lys94, which weakens the interactions between p53 and MDM2. From the systematic biology point of view, the regulation of p53 by MDM2 is extremely sensitive to the strength of the p53-MDM2 interaction. The avianization of the interactions between p53 and MDM2 by Nutlin-3a can promote p53 to restore its suppression functions on tumor development.&lt;/sec&gt;&lt;sec&gt;This study may be helpful in understanding the molecular mechanisms of p53-MDM2 complex instability mediated by Nutlin-3a and also in searching for the effective inhibitors of p53-MDM2 interaction.&lt;/sec&gt;

Abstract 2998: Inhibition of MDM2-p53 interaction by alrizomadlin (APG-115) induces pyroptotic cell death in gasdermin E (GSDME)-expressing cancer cells

Abstract Mouse double minute-2 (MDM2)-p53 inhibitor alrizomadlin (APG-115) is an investigational agent known to induce apoptosis of TP53-wild type cancer cells (Aguilar et al, J Med Chem 2017). Emerging evidence suggests that activation of p53 by alrizomadlin also promotes antitumor immunity in the tumor microenvironment (Fang et al, JITC 2019; Zhou et al, Nat Immunol 2021), but the links between these processes are incompletely understood. Pyroptosis refers to inflammatory programmed cell death. Central to this process is the family of gasdermins, which can form pores in cell plasma membranes, resulting in lysis and release of immune stimulants. In cells expressing these proteins, GSDME can be cleaved by caspase-3, which converts noninflammatory apoptosis to pyroptosis (Zhang et al, Nature 2020). In this context, caspase-3/GSDME appears to represent a switch between apoptosis and pyroptosis. Given that alrizomadlin elicits its apoptogenic activity primarily by activating caspase-3, we hypothesized that the MDM2-p53 inhibitor might also induce pyroptosis in GSDME-expressing cells by cleaving caspases. Our study demonstrated that alrizomadlin uniformly elicited robust pyroptosis in GSDME-expressing cancer cells. After treatment with alrizomadlin, the dying cells showed swelling with plasma membrane blebbing characteristic of pyroptosis. Alrizomadlin treatment upregulated biomarkers of pyroptosis, inducing activation of caspase-3, promoting cleavage of GSDME, and increasing release of lactate dehydrogenase (LDH). After a short drug exposure of 24 hours, alrizomadlin elicited concurrent apoptotic and pyroptotic tumor cell death, as evidenced by coexistence of the hallmarks of apoptosis (PARP-1 cleavage) and pyroptosis (caspase-3 cleavage and activated GSDME) markers. When the treatment duration was extended to 48 hours, cleavage of GSDME continued to increase whereas PARP-1 cleavage became nearly undetectable, suggesting a conversion from apoptosis to pyroptosis. Inhibition of caspases by pan-caspase inhibitor Q-VD-OPh (quinolyl-valyl-O-methylaspartyl-[-2,6-difluorophenoxy]-methyl ketone) abolished not only alrizomadlin-induced caspase-3 and GSDME cleavage but also reduced LDH release and cell death without inducing morphologic changes associated with pyroptosis. Taken together, these results suggest that, in addition to apoptosis, MDM2-p53 inhibitor alrizomadlin induces caspase-mediated pyroptosis in GSDME-expressing cancer cells. In this study, we reveal for the first time that apoptosis-inducing, alrizomadlin induces both apoptosis and pyroptosis in GSDME-expressing cancer cells. GSDME-dependent pyroptosis may be a previously unrecognized mechanism of action for alrizomadlin to exert antitumor immunity, with potentially important implications for clinical development of therapy involving MDM2-p53 inhibition. Citation Format: Qiuqiong Tang, Douglas D. Fang, Huidan Yu, Bingxing Wu, Yan Yin, Dajun Yang, Yifan Zhai. Inhibition of MDM2-p53 interaction by alrizomadlin (APG-115) induces pyroptotic cell death in gasdermin E (GSDME)-expressing cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2998.

P53-MDM2 interaction monitoring and inhibitors potency evaluation based on CRISPR-Cas12a sensing platform

Protein-protein interactions (PPIs) monitoring is critical to reveal cellular fundamental mechanism and facilitate drugs discovery. Nevertheless, the facial and robust protein 53 (p53)-murine double minute2 (MDM2) interaction detection methods remain challenging. Herein, we developed a PPIs detection platform based on CRISPR-Cas12a sensing system for the first time for p53-MDM2 interaction monitoring and inhibitors potency evaluation, designated Cas-PPIor (Cas12a-mediated PPIs detector). Inspired by the conformational-dependent consensus DNA binding ability of p53, a double stranded DNA (dsDNA) probe was designed elaborately through incorporating Cas12a activation DNA sequence into the specific p53 DNA-binding sequence. Thus, the PPI event can then be transduced into the collateral cleavage activity of Cas12a. As both the Cas12a/CRISPR RNA (crRNA) complex and p53 can bind to the same dsDNA probe in a competitive manner, the activated Cas12a mediated fluorescent readout scaled negatively with the p53 binding. Accordingly, we monitored the p53-MDM2 interaction process as well as its inhibition by a small-molecule antagonist. Based on the sequence specific binding of wild p53, our designed Cas-PPIor achieved high accuracy for differentiation of wild-type p53 cells from p53 mutation or deletion cells. Through discriminating p53 levels from cellular matrix treated with enantiomers of Nutlin-3, the assay also demonstrated reliable capability to evaluate drugs antiproliferative potency. By integrating the DNA binding ability of proteins with intrinsic flexible programmability and outstanding sensitivity of Cas12a, the proposed Cas-PPIor methodology hold great potential to enable accurate and facial PPIs monitoring and inhibitors potency evaluations.

Chalcones as Promising Antitumor Agents by Targeting the p53 Pathway: An Overview and New Insights in Drug-Likeness.

The p53 protein is one of the most important tumor suppressors that are frequently inactivated in cancer cells. This inactivation occurs either because the TP53 gene is mutated or deleted, or due to the p53 protein inhibition by endogenous negative regulators, particularly murine double minute (MDM)2. Therefore, the reestablishment of p53 activity has received great attention concerning the discovery of new cancer therapeutics. Chalcones are naturally occurring compounds widely described as potential antitumor agents through several mechanisms, including those involving the p53 pathway. The inhibitory effect of these compounds in the interaction between p53 and MDM2 has also been recognized, with this effect associated with binding to a subsite of the p53 binding cleft of MDM2. In this work, a literature review of natural and synthetic chalcones and their analogues potentially interfering with p53 pathway is presented. Moreover, in silico studies of drug-likeness of chalcones recognized as p53–MDM2 interaction inhibitors were accomplished considering molecular descriptors, biophysiochemical properties, and pharmacokinetic parameters in comparison with those from p53–MDM2 in clinical trials. With this review, we expect to guide the design of new and more effective chalcones targeting the p53 pathway.

MDM2 inhibitors: Targeting p53-MDM2 interaction to anti-cancer

P53 is a recognized tumor suppressor gene, which mainly depends on the activity of its transfer factor to realize the tumor suppressor effect. Mouse two-minute 2 (MDM2) is an important inhibitor of p53. When combined with MDM2, the activity of p53 will be reduced, and the anti-cancer effect will be weakened. According to the mechanism between p53 and MDM2, researchers focus on the inhibitors to inhibit their binding. Through a large number of drug screening methods and means, this article has found many new inhibitors of p53-MDM2 interaction, most of which are still in the clinical research stage. Specifically, we classify the drugs based on their different action mechanisms. Firstly, some drugs combine with MDM2 to inhibit the p53-MDM2 interaction. They are Siremadlin (NVP-HDM201), RG7112, and NVP-CGM09. While some act on p53, they rely on their induction of p53 signalling and inhibition of tumour cell proliferation in p53 wild-type tumor cell lines, like MK-8242 and KRT-232(AMG-232). What’s more, one inhibitor’s action bases on P53 and MDM2 in T cells is APG-115. And last but not least, there are also several drugs that stable tumor suppressor TP53, leading to p53 activation and inducing cell cycle arrest and apoptosis, they are Idasanutlin (RG7388) and Milademetan (DS-3032/RAIN-32). Furthermore, clinical studies are finding that monotherapy does not deliver a powerful therapeutic effect. Various combination strategies are being explored with MDM2 inhibitors preclinically and in the clinic. This article will talk about some specific combinations: APG-115 combine with immune checkpoint inhibitor PD-1/PD-L1, MDM2 inhibitors combine with BCL-2 inhibitors, anti-CD20 therapeutic antibodies, and the last, combine with alkylating agents.

CDK9 activity is critical for maintaining MDM4 overexpression in tumor cells

The identification of the essential role of cyclin-dependent kinases (CDKs) in the control of cell division has prompted the development of small-molecule CDK inhibitors as anticancer drugs. For many of these compounds, the precise mechanism of action in individual tumor types remains unclear as they simultaneously target different classes of CDKs – enzymes controlling the cell cycle progression as well as CDKs involved in the regulation of transcription. CDK inhibitors are also capable of activating p53 tumor suppressor in tumor cells retaining wild-type p53 gene by modulating MDM2 levels and activity. In the current study, we link, for the first time, CDK activity to the overexpression of the MDM4 (MDMX) oncogene in cancer cells. Small-molecule drugs targeting the CDK9 kinase, dinaciclib, flavopiridol, roscovitine, AT-7519, SNS-032, and DRB, diminished MDM4 levels and activated p53 in A375 melanoma and MCF7 breast carcinoma cells with only a limited effect on MDM2. These results suggest that MDM4, rather than MDM2, could be the primary transcriptional target of pharmacological CDK inhibitors in the p53 pathway. CDK9 inhibitor atuveciclib downregulated MDM4 and enhanced p53 activity induced by nutlin-3a, an inhibitor of p53-MDM2 interaction, and synergized with nutlin-3a in killing A375 melanoma cells. Furthermore, we found that human pluripotent stem cell lines express significant levels of MDM4, which are also maintained by CDK9 activity. In summary, we show that CDK9 activity is essential for the maintenance of high levels of MDM4 in human cells, and drugs targeting CDK9 might restore p53 tumor suppressor function in malignancies overexpressing MDM4.

Abstract 4872: Therapeutic value of BCL2 and MDM2-p53 axis in ovarian clear cell and endometrioid carcinomas with wild type TP53

Abstract Background: Apoptosis is the therapeutic goal following the administration of anti-cancer drugs. BCL2 and p53 are two important nodes in the apoptosis signaling pathway. Previous reports have shown that the anti-apoptotic protein BCL2 and p53 degrader MDM2 are overexpressed in many solid neoplasms, including ovarian cancers, and associated with poor clinical outcome. Purpose: Since monotherapy in cancer is generally not providing long-lasting clinical responses, here, we hypothesize that concomitant p53 activation (by an inhibitor of MDM2-p53 interaction, e.g. AMG232) and BCL2 inhibition (by venetoclax) induce maximum apoptosis and markedly reduce tumor cell proliferation in ovarian clear cell and endometrioid carcinomas with wild type (WT) TP53. Methods: We tested the anti-proliferative and apoptotic activity of venetoclax (V) alone, AMG 232 alone (A), and a combination of V plus A in ovarian clear cell carcinoma (OVISE cells) and ovarian endometrioid carcinoma cell lines (A2780 &amp; isogenic Cisplatin resistant A2780CisR). Results: 1) A binds the MDM2 protein, blocks MDM2-p53 interaction, and induces p53 expression and activity, 2) p53 effector molecule p21 is robustly induced following the treatment of A, 3) the anti-proliferative activity of V or A was observed by 3D-ON-TOP clonogenic assay and real-time monitoring in an IncuCyte Zoom, 4) all three cell lines exhibited an increase in annexin V positivity (initiation of apoptotic activity) following V or A treatment, 5) importantly, a combination of V plus A robustly induced the apoptotic markers e.g. cleaved-CASPASE3/7, cleaved PARP1 and BIM protein expression in all cell lines, 6) high mitochondrial depolarization was also observed following the combination of treatment, 7) similar to protein expression data, mRNA data also showed that pro-apoptotic/cell cycle inhibitor transcripts such as p21 and PUMA mRNA expression were significantly increased and 8) normoxic HIF1α degradation is not rescued following the treatment of MDM2-p53 interacting inhibitor A however A-induced p53 activation inhibits hypoxic HIF1α accumulation. Conclusion: These data strongly support the further evaluation of dual BCL2/MDM2 targeting as a therapeutic strategy for ovarian clear cell and endometrioid carcinomas patients that retain WT-TP53. Citation Format: Pradip K. De, Jennifer C. Aske, Joseph P. Costello, Ethan Thompson, Nandini Dey. Therapeutic value of BCL2 and MDM2-p53 axis in ovarian clear cell and endometrioid carcinomas with wild type TP53 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4872.

Non peptidic small molecular inhibitors of the p53-MDM2 interaction

Cancer is a tumorous disease, which involves the unwanted cell growth and cell division. The imbalance or inactivity of the apoptosis in the body is responsible for the occurrence of tumour and cancer. This apoptosis is regulated by the p53 protein, which is tumour suppressor protein. In the cancer cells, this p53 has been inhibited by the MDM2 protein. MDM2 interact with the p53 and make it inactive. This p53-MDM2 interaction is responsible for the cancer genesis. If we target this interaction, then we can initiate the apoptosis in the cancer cells by making the free p53 protein. There are many strategies to inhibit this p53-MDM2 interaction. Among them non-peptidic small molecule inhibitors are the convenient approach. Small molecule inhibitors have a three pocket binding, so they bind with p53 binding pocket (Trp 23, Leu 26 and Phe 19), present in the MDM2 protein. That is how it spares the p53 protein and makes it available in the cancer cells. Hence, small molecule inhibitors successfully inhibit the p53-MDM2 interaction and can initiate the apoptosis in the cancer cells, which are having the un-mutated p53 protein. They can’t inhibit this interaction in the cells which contains the mutated or deleted p53 protein. Hence, this limitation must be addressed. Many of the small molecular MDM2 inhibitors have been successfully entered into the clinical trials and they are performing well. The clinical data indicate that the small molecular MDM2 inhibitors are having very low toxicity to the normal cells. And they are non-genotoxic so they are near to nontoxic to the normal cells. But none of the any small molecule MDM2 inhibitor has been enters into the market yet. So till then, it has required advancement and research to make more selective and specific for the cancer cells over the normal cells. Keywords: Cancer, Apoptosis, p53 protein, MDM2 protein, p53-MDM2 interaction, Three pocket binding, Small molecule p53-MDM2 interaction inhibitors.

Discovery of 1,2‐Naphthoquinone Derivatives as Potent p53‐MDM2 Interaction Inhibitors

Discovery of 1,2-naphthoquinone analogues as potent p53-MDM2 interaction inhibitors.

Antitumor immunity augments the therapeutic effects of p53 activation on acute myeloid leukemia

The negative regulator of p53, MDM2, is frequently overexpressed in acute myeloid leukemia (AML) that retains wild-type TP53 alleles. Targeting of p53-MDM2 interaction to reactivate p53 function is therefore an attractive therapeutic approach for AML. Here we show that an orally active inhibitor of p53-MDM2 interaction, DS-5272, causes dramatic tumor regressions of MLL-AF9-driven AML in vivo with a tolerable toxicity. However, the antileukemia effect of DS-5272 is markedly attenuated in immunodeficient mice, indicating the critical impact of systemic immune responses that drive p53-mediated leukemia suppression. In relation to this, DS-5272 triggers immune-inflammatory responses in MLL-AF9 cells including upregulation of Hif1α and PD-L1, and inhibition of the Hif1α-PD-L1 axis sensitizes AML cells to p53 activation. We also found that NK cells are important mediators of antileukemia immunity. Our study showed the potent activity of a p53-activating drug against AML, which is further augmented by antitumor immunity.

Synthesis, Biological and In Silico Evaluation of Pure Nucleobase-Containing Spiro (Indane-Isoxazolidine) Derivatives as Potential Inhibitors of MDM2-p53 Interaction.

Nucleobase-containing isoxazolidines spiro-bonded to an indane core have been synthesized in very good yields by regio- and diastereoselective 1,3-dipolar cycloaddition starting from indanyl nitrones and N-vinylnucleobases by using environmentally benign microwave technology. The contemporary presence of various structural groups that are individually active scaffolds of different typology of drugs, has directed us to speculate that these compounds may act as inhibitors of MDM2–p53 interaction. Therefore, both computational calculations and antiproliferative screening against A549 human lung adenocarcinoma cells and human SH-SY5Y neuroblastoma cells were carried out to support this hypothesis.

Abstract 4839: Double knockdown of MDM4 and MDM2 modulates the antitumor effects of cytotoxic drugs in colon and gastric cancer cells expressing high levels of MDM4

Abstract Introduction and Aim: Inactivation of the TP53 tumor suppressor gene is important for cancer development and progression. Wild-type (wt) TP53 is inactivated in various types of cancers including colon and gastric cancers by upregulated murine double minute homolog 2 (MDM2) and MDM4. We previously reported that simultaneous knockdown of MDM4 and MDM2 using synthetic DNA-modified siRNAs revived p53 activity and synergistically inhibited in vitro cell growth in cancer cells with wild-type TP53 and high MDM4 expression (wtTP53/highMDM4), whereas only MDM2 knockdown but not MDM4 knockdown suppressed that of high MDM2 expression cancer cells. In the present study, we investigated the combined activity of MDM4/MDM2 double knockdown and cytotoxic drugs (5-fluorouracil (5-FU), cisplatin, oxaliplatin) to develop a new therapy for gastric and colon cancers with wtTP53/highMDM4. Experimental procedure: Two colon (HCT116, LoVo) and two gastric cancer cell lines (NUGC-4, SNU-1) were used. Respective synthetic DNA-modified siRNAs against MDM4 (chiMDM4) and MDM2 (chiMDM2) were transfected using Lipofectamine RNAiMAX. Cell viability was determined by WST-8 assays. Expression of p53, p21, MDM2, MDM4, and β-actin were analyzed by immunoblotting. Cell cycle distribution was analyzed by flow cytometry. In vivo antitumor effects were examined using nude mice carrying HCT116 xenograft tumors. siRNAs with atelocollagen were intratumorally injected weekly and 5-FU was intraperitoneally administered three times per week. Results: MDM4/MDM2 double knockdown with the siRNAs enhanced in vitro antitumor activity of 5-FU in all four wtTP53/highMDM4 cell lines (HCT116, LoVo, SNU-1, and NUGC-4) and cisplatin and oxaliplatin in gastric (NUGC-4) and colon cancer cell lines (HCT116, LoVo), respectively. Exposure to 5-FU increased p53 and its downstream gene products (p21, PUMA, MDM2), and induced cell cycle arrest in the G1 phase. MDM4/MDM2 double knockdown suppressed MDM2, and enhanced expression of p53 and p21 and arrested G1. p53-MDM2 forms a negative feedback loop. Enhanced antitumor effects of 5-FU by MDM4/MDM2 double knockdown may be attributed to blocking this feedback loop, in addition to direct suppression of MDM4/MDM2. Since MDM2 interacts directly with molecules like RB, p21, and E2F1, other than p53, MDM2 knockdown may have some advantages over peptides or small molecular inhibitors of p53-MDM2 interaction in such combination therapies. Intratumor injection of chiMDM4/chiMDM2 suppressed in vivo tumor growth and boosted the antitumor effects of 5-FU in a xenograft model using HCT116 cells. Conclusion: Combining MDM4/MDM2 knockdown and conventional cytotoxic drugs may be a promising treatment strategy for wtTP53/highMDM4 gastrointestinal cancers. Citation Format: Mamiko Imanishi, Yoshiyuki Yamamoto, Shinji Endo, Kenji Yamato, Ichinosuke Hyodo. Double knockdown of MDM4 and MDM2 modulates the antitumor effects of cytotoxic drugs in colon and gastric cancer cells expressing high levels of MDM4 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4839.

Tetra-substituted pyrrole derivatives act as potent activators of p53 in melanoma cells.

Cutaneous melanoma, the most aggressive form of skin cancer, is characterized by activating BRAF mutations. Despite the initial success of selective BRAF inhibitors, only few patients exhibited complete responses, whereas many showed disease progression. Melanoma is one of the few types of cancer in which p53 is not frequently mutated, but p53 inactivation can be indirectly achieved by a stable activation of MDM2 induced by a deletion in CDKN2A (Cyclin Dependent Kinase Inhibitor 2A) locus, encoding for p16INK4A and p14ARF, two tumor suppressor genes. In this study, we tested the efficacy of the previously synthesized tetra-substituted pyrrole derivatives, 8g, 8h and 8i, in melanoma cell lines, and we compared the effects of the most active of these, the 8i compound, with that exerted by Nutlin 3, a well-known inhibitor of p53-MDM2 interaction. The obtained results showed that 8i potentiates the inhibitory effect of Nutlin 3 and the combined use of 8i and Nutlin 3 triggers apoptosis and significantly impairs melanoma viability. Finally, the 8i compound reduces p53-MDM2 interaction and induces p53-HSP90 complex formation, suggesting that the observed raise in p53 transcriptional activity could be mediated by HSP90. Because the main feature of melanoma is the resistance to most chemotherapeutics, our studies suggest that the 8i tetra-substituted pyrrole derivative, restoring p53 functions and its transcriptional activities, may have potential application, at least as adjuvant, in the treatment of human melanoma.

2,4,5-Tris(alkoxyaryl)imidazoline derivatives as potent scaffold for novel p53-MDM2 interaction inhibitors: Design, synthesis, and biological evaluation.

Imidazoline-based small molecule inhibitors of p53-MDM2 interaction intended for the treatment of p53 wild-type tumors are the promising structures for design of anticancer drugs. Based on fragment approach we have investigated a key role of substituents in cis-imidazoline core for biological activity of nutlin family compounds. Although the necessity of the substituents in the phenyl rings of cis-imidazoline has been shown, there are no studies in which the replacements of a halogen by other substituents have been investigated. A series of simple cis-imidazoline derivatives containing halogen, hydroxy and alkoxy-substituents were synthesized. The biological activity of the compounds was studied using assays of cytotoxicity (MTT) and p53 level. It was found that the hydroxyl-derivatives were not cytotoxic whereas the alkoxy analogues were the same or more active as halogen-substituted compounds in cell viability test. The synthesized alkoxy derivatives induced an increase of p53 level and did not promote necrotic cell death in the concentration up to 40 µM.

Ablation of Cancer Stem Cells by Therapeutic Inhibition of the MDM2-p53 Interaction in Mucoepidermoid Carcinoma.

Unique cells characterized by multipotency, self-renewal, and high tumorigenic potential have been recently discovered in mucoepidermoid carcinomas. These cells are defined by high aldehyde dehydrogenase activity and high CD44 expression (ALDHhighCD44high) and function as cancer stem cells (CSC). It has been recently shown that p53 regulates cell differentiation, suggesting that induction of p53 by therapeutic blockade of the MDM2-p53 interaction may constitute a novel strategy to ablate CSCs. Here, we evaluated the effect of a small-molecule inhibitor of MDM2-p53 interaction (MI-773) on the fraction of CSCs in mucoepidermoid carcinoma. Human mucoepidermoid carcinoma cells (UM-HMC-1,-3A,-3B) were used to assess the effect of MI-773 on cell survival, cell cycle, fraction of CSCs, and expression of p53, p21, MDM2, and Bmi-1 (key regulator of self-renewal). Mice bearing xenograft tumors generated with these mucoepidermoid carcinoma cells were treated with MI-773 to determine the effect of MDM2-p53 inhibition on CSCs in vivo. MDM2 is highly expressed in human mucoepidermoid carcinoma tissues. MI-773 induced expression of p53 and its downstream targets p21 and MDM2, caused G1 cell-cycle arrest, and induced mucoepidermoid carcinoma tumor cell apoptosis in vitro. Importantly, a marked decrease in expression of Bmi-1 and in the fraction of ALDHhighCD44high (CSCs) was caused by MI-773 in vitro and in mice harboring mucoepidermoid carcinoma xenografts. Collectively, these data demonstrate that MI-773 reduces the fraction of CSCs, suggesting that patients with mucoepidermoid carcinoma might benefit from therapeutic inhibition of the MDM2-p53 interaction.