A fluorinated indole-based MDM2 antagonist selectively inhibits the growth of p53^wt osteosarcoma cells

Area of Science:

• Medicinal Chemistry
• Molecular Biology
• Structural Biology

Background:

• The p53 protein is a critical tumor suppressor involved in DNA repair and cell cycle regulation.
• Dysregulation of p53, often due to MDM2 overexpression, is a key event in cancer development.
• Targeting MDM2 to restore p53 activity is a therapeutic strategy for p53 wild-type cancers.

Purpose of the Study:

• To evaluate the biological activity and stereoselectivity of a novel fluoro-substituted indole-based MDM2 antagonist.
• To investigate the compound's mechanism of action in cancer cells.
• To elucidate the structural basis of MDM2-antagonist interaction.

Main Methods:

• Fluorescence polarization (FP), nuclear magnetic resonance (NMR), and microscale thermophoresis (MST) assays were used to assess binding affinity.
• Cellular assays measured p53 levels, p53-target gene expression (CDKN1A, MDM2), cell cycle arrest, and cell growth inhibition.
• X-ray crystallography was employed to determine the binding mode of the compound to MDM2.

Main Results:

• Both enantiomers and corresponding carboxylic acids of the esterified compound showed binding to MDM2 with K_i/K_D values around 1 μm.
• The (R)-enantiomer ester (R)-5a demonstrated cellular activity, increasing p53 levels and inducing target gene expression.
• Selective cell cycle arrest and growth inhibition were observed in p53 wild-type cancer cells, with structural analysis revealing a classical binding mode.

Conclusions:

• The study validates the anticancer potential of the novel indole-based MDM2 antagonist.
• The compound exhibits stereoselective biological activity and a well-defined binding interaction with MDM2.
• These findings provide a foundation for further optimization of MDM2 inhibitors for cancer therapy.