A Sos proteomimetic as a pan-Ras inhibitor

Area of Science:

• Molecular Biology
• Cell Biology
• Drug Discovery

Background:

• Aberrant Ras signaling drives hyperproliferative diseases, making Ras pathway components key targets for drug development.
• The Son of sevenless (Sos) guanine nucleotide exchange factor modulates Ras cellular activity.
• The Ras-Sos complex structure enables rational design of Ras-targeting ligands.

Purpose of the Study:

• To design and construct a synthetic protein mimic of Sos.
• To investigate the mimic's ability to engage Ras and modulate downstream signaling.
• To evaluate the proteomimetic's cellular uptake, stability, and selective toxicity.

Main Methods:

• Construction of a synthetic Sos protein mimic based on the Ras-Sos crystal structure.
• Engagement studies using chemoproteomics to identify targeted GTPases.
• Assessment of proteolytic stability and cellular entry via macropinocytosis.
• Evaluation of selective toxicity in cancer cells with varying macropinocytosis levels.

Main Results:

• The synthetic Sos mimic effectively engages wild-type and oncogenic Ras.
• The proteomimetic modulates downstream kinase signaling pathways.
• The mimic demonstrates resistance to degradation and cellular entry via macropinocytosis.
• Selective toxicity was observed in cancer cells exhibiting upregulated macropinocytosis, including those with Ras mutations.

Conclusions:

• A synthetic Sos mimic represents a promising therapeutic agent for Ras-driven cancers.
• The proteomimetic's mechanism involves disrupting Ras-Sos interactions and leveraging macropinocytosis for targeted delivery.
• This approach offers a novel strategy for treating hyperproliferative diseases linked to aberrant Ras signaling.