A Guanidyl-Based Bivalent Peptidomimetic Inhibits K-Ras Prenylation and Association with c-Raf

Area of Science:

• Oncology
• Molecular Biology
• Medicinal Chemistry

Background:

• K-Ras mutations are common in cancer, and its unusual lipid modification presents therapeutic challenges.
• Targeting K-Ras protein-protein interactions (PPIs) is a potential strategy for cancer therapy.

Purpose of the Study:

• To design and synthesize novel bivalent dual inhibitors targeting K-Ras's interaction with farnesyltransferase (FTase) and geranylgeranyltransferase I (GGTase I).
• To evaluate the efficacy of these inhibitors in disrupting K-Ras processing and localization.

Main Methods:

• Design of bivalent dual inhibitors recognizing K-Ras active pocket and FTase/GGTase I acidic surface.
• Structure-activity-relationship (SAR) study to identify lead compound 8b.
• Cell-based assays to assess K-Ras processing inhibition and Rap-1A processing.
• Fluorescent imaging to analyze K-Ras plasma membrane localization and c-Raf interaction.

Main Results:

• Compound 8b, a peptidomimetic FTI-277 derivative, demonstrated significant inhibition of K-Ras processing.
• 8b disrupted K-Ras localization to the plasma membrane and impaired its interaction with c-Raf.
• Rap-1A processing remained largely unaffected by 8b, indicating specificity.
• The parent compound FTI-277 showed no significant activity in these assays.

Conclusions:

• Targeting K-Ras PPI interfaces offers a promising alternative to traditional Ras-directed cancer therapies.
• Bivalent dual inhibitors like 8b can effectively disrupt oncogenic K-Ras signaling pathways.
• Further development of K-Ras PPI inhibitors may lead to new cancer treatment strategies.