Inhibition of mutant RAS-RAF interaction by mimicking structural and dynamic properties of phosphorylated RAS

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• RAS proteins are key regulators of cell signaling, and their mutations are common in cancer.
• The
• undruggability
• of RAS proteins necessitates novel therapeutic strategies.
• Phosphorylation is a post-translational modification that affects RAS protein function and sensitivity to inhibitors.

Purpose of the Study:

• To investigate the impact of phosphorylation on the dynamics of wild-type HRAS (HRAS^WT).
• To explore the potential of small therapeutic molecules to mimic the effects of phosphorylation on mutant HRAS (HRAS^G12D).
• To target the Switch I region of HRAS^G12D to disrupt RAS/RAF interactions.

Main Methods:

• Molecular dynamics (MD) simulations of phosphorylated HRAS.
• Computational analysis of ligand-induced changes in HRAS^G12D structure and dynamics.
• In vitro validation using HEK293T cells expressing HRAS^G12D mutant protein.

Main Results:

• Phosphorylation of Y32 in HRAS distorts the Switch I region, affecting the RAS/RAF interface.
• Small therapeutic molecules targeting Switch I in HRAS^G12D promote the detachment of Switch I from the nucleotide-binding pocket.
• Ligand-mediated displacement of Switch I is energetically favorable and inhibits HRAS^G12D/RAF interaction in vitro.

Conclusions:

• Targeting the Switch I region of HRAS, particularly by making Y32 accessible, is a promising strategy.
• This approach may overcome the "undruggability" of RAS proteins and lead to new cancer therapies.
• The findings open new avenues for developing inhibitors against mutant RAS proteins.