AMG232

AMG-232 is a novel inhibitor of p53-MDM2 with IC50 value of 9.2 nM [1].

Tumor protein p53 (p53) is a very unstable protein with a half-life ranging from 5 to 30 min and participates in a variety of anticancer processes, such as inducing cell apoptosis and inhibiting angiogenesis. Mouse double minute 2 homolog (MDM2), also named as E3 ubiquitin-protein ligase Mdm2, involves in mediating p53 tumor suppressor. It has been conclusively demonstrated p53 is under-expressed in tumor cells [2].

AMG-232 is a potent p53-MDM2 interaction inhibitor and is regarded as a promising drug in clinic. When tested with SJSA-1 tumor cell line, AMG-232 treatment resulted in cell-cycle arrest and inhibition of tumor cell proliferation via binding to MDM2 protein and robustly inducing p53 activity. It was shown that p53-MDM2 bond rang from a Kd of 60 to 700 nM Depending on the length of p53 peptide [3].

In mouse model with SJSA-1 tumor cells subcutaneous xenograft, co-administration of AMG-232 and chemotherapies induced DNA damage and p53 activity which resulted in significantly superior antitumor efficacy and regression through arresting cell growth and inducting apoptosis [3].

References:
[1].  Rew, Y., et al., Discovery of AM-7209, a potent and selective 4-amidobenzoic acid inhibitor of the MDM2-p53 interaction. J Med Chem, 2014. 57(24): p. 10499-511.
[2].  Moll, U.M. and O. Petrenko, The MDM2-p53 interaction. Mol Cancer Res, 2003. 1(14): p. 1001-8.
[3].  Canon, J., et al., The MDM2 Inhibitor AMG 232 Demonstrates Robust Antitumor Efficacy and Potentiates the Activity of p53-Inducing Cytotoxic Agents. Mol Cancer Ther, 2015. 14(3): p. 649-58.

Potent effect of the MDM2 inhibitor AMG232 on suppression of glioblastoma stem cells.[Pubmed:30022047]

Cell Death Dis. 2018 Jul 18;9(8):792.

Testing new ways to identify untapped opportunities for glioblastoma therapies remains highly significant. Amplification and overexpression of MDM2 gene is frequent in glioblastoma and disrupting the MDM2-p53 interaction is a promising strategy to treat the cancer. RG7112 is the first-in class inhibitor and recently discovered AMG232 is the most potent MDM2 inhibitor known to date. Here, we compared the effects of these two clinical MDM2 inhibitors in six glioblastoma cell lines and ten patient-derived glioblastoma stem cells. Targeted sequencing of the TP53, MDM2 genes and whole transcriptome analysis were conducted to verify genetic status associated with sensitivity and resistance to the drugs. Although TP53 wild-type glioblastoma cell lines are similarly sensitive to AMG232 and RG7112, we found that four TP53 wild-type out of ten patient-derived glioblastoma cells are much more sensitive to AMG232 than RG7112 (average IC50 of 76 nM vs. 720 nM). Among these, 464T stem cells containing MDM2 gene amplification were most sensitive to AMG232 with IC50 of 5.3 nM. Moreover, AMG232 exhibited higher selectivity against p53 wild-type cells over p53 mutant stem cells compared to RG7112 (average selectivity of 512-fold vs. 16.5-fold). Importantly, we also found that AMG232 is highly efficacious in three-dimensional (3D) tumor spheroids growth and effectively inhibits the stemness-related factors, Nestin and ZEB1. Our data provide new evidence that glioblastoma stem cells have high susceptibility to AMG232 suggesting the potential clinical implications of MDM2 inhibition for glioblastoma treatment. These will facilitate additional preclinical and clinical studies evaluating MDM2 inhibitors in glioblastoma and direct further efforts towards developing better MDM2-targeted therapeutics.

A yeast two-hybrid system for the screening and characterization of small-molecule inhibitors of protein-protein interactions identifies a novel putative Mdm2-binding site in p53.[Pubmed:29121928]

BMC Biol. 2017 Nov 9;15(1):108.

BACKGROUND: Protein-protein interactions (PPIs) are fundamental to the growth and survival of cells and serve as excellent targets to develop inhibitors of biological processes such as host-pathogen interactions and cancer cell proliferation. However, isolation of PPI inhibitors is extremely challenging. While several in vitro assays to screen for PPI inhibitors are available, they are often expensive, cumbersome, and require large amounts of purified protein. In contrast, limited in vivo assays are available to screen for small-molecule inhibitors of PPI. METHODS: We have engineered a yeast strain that is suitable for screening of small-molecule inhibitors of protein-protein interaction using the Yeast 2-hybrid Assay. We have optimised and validated the assay using inhibitors of the p53-Mdm2 interaction and identified a hitherto unreported putative Mdm2-binding domain in p53. RESULTS: We report a significantly improved and thoroughly validated yeast two-hybrid (Y2H) assay that can be used in a high throughput manner to screen for small-molecule PPI inhibitors. Using the p53-Mdm2 interaction to optimize the assay, we show that the p53-Mdm2 inhibitor nutlin-3 is a substrate for the yeast ATP-binding cassette (ABC) transporter Pdr5. By deleting nine ABC transporter-related genes, we generated a ABC9Delta yeast strain that is highly permeable to small molecules. In the ABC9Delta strain, p53-Mdm2 interaction inhibitors, like AMG232 and MI-773, completely inhibited the p53-Mdm2 interaction at nanomolar concentrations in the Y2H assay. In addition, we identified a conserved segment in the core DNA-binding domain of p53 that facilitates stable interaction with Mdm2 in yeast cells and in vitro. CONCLUSION: The Y2H assay can be utilized for high-throughput screening of small-molecule inhibitors of PPIs and to identify domains that stabilize PPIs.

AMG 232 is a potent, selective and orally available inhibitor of p53-MDM2 interaction, with an IC50 of 0.6 nM. AMG 232 binds to MDM2 with a Kd of 0.045 nM.

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