A Novel Class of Common Docking Domain Inhibitors That Prevent ERK2 Activation and Substrate Phosphorylation

Area of Science:

• Oncology
• Biochemistry
• Medicinal Chemistry

Background:

• Extracellular signal-regulated kinases (ERK1/2) are key mitogen-activated protein kinases (MAPKs) implicated in cancer progression.
• ERK1/2 signaling is regulated by specific protein-docking sites, including the D-recruitment site (DRS), distinct from the active ATP-binding site.
• Targeting these docking sites offers a potential alternative to conventional ATP-competitive inhibitors, which face challenges in cancer therapy.

Purpose of the Study:

• To identify and characterize novel inhibitors targeting the ERK DRS.
• To develop non-ATP-competitive inhibitors that disrupt ERK1/2 pro-tumorigenic functions.
• To explore new therapeutic strategies for cancers driven by aberrant ERK signaling.

Main Methods:

• Screening of a large synthetic combinatorial library (>30 million compounds) to identify DRS-displacing molecules.
• Structure-activity relationship optimization of lead compounds, focusing on a tertiary amine hub with cyclic guanidino branches.
• Biochemical assays to assess inhibitor efficacy in blocking ERK2 phosphorylation and interaction studies (NMR, X-ray crystallography) to confirm binding mode.

Main Results:

• Identification of a new class of 10 compounds targeting the ERK DRS, sharing a common molecular scaffold.
• Compound 2507-1 demonstrated inhibition of DRS-substrate phosphorylation and MEK1-mediated ERK2 phosphorylation.
• Structural analysis of analogue 2507-8 confirmed binding to the ERK2 DRS via specific interactions, revealing a common binding mode for the identified inhibitors.

Conclusions:

• A novel class of non-ATP-competitive ERK inhibitors targeting the DRS has been discovered.
• These inhibitors function by disrupting critical protein-protein interactions mediated by the DRS.
• The findings provide a foundation for developing new cancer therapeutics that modulate ERK signaling through docking site inhibition.