Silent mutations reveal therapeutic vulnerability in RAS Q61 cancers

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• RAS family proteins are key oncogenes in human cancers, with KRAS(G12C) inhibitors showing clinical efficacy.
• Existing therapies do not target NRAS, HRAS, or KRAS variants other than G12C, leaving a significant unmet need.
• The functional status of RAS proteins is intricately linked to post-transcriptional modifications like alternative splicing.

Purpose of the Study:

• To elucidate the mechanism by which a functional KRAS(Q61K) variant is produced.
• To identify novel therapeutic targets for cancers driven by RAS(Q61) mutations.
• To explore the role of silent mutations in oncogene activation and potential therapeutic intervention.

Main Methods:

• Investigated the role of the silent KRAS G60G mutation in KRAS(Q61K) protein production using molecular biology techniques.
• Analyzed alternative splicing events and premature protein termination associated with KRAS mutations.
• Designed and tested mutant-specific antisense oligonucleotides targeting exonic splicing enhancer (ESE) motifs to inhibit aberrant splicing.

Main Results:

• A silent KRAS G60G mutation is required for the production of functional KRAS(Q61K) by preventing cryptic splice site formation and alternative splicing.
• KRAS(Q61K) and the G60G/A59A silent mutation were found to be concordant in three independent pan-cancer cohorts.
• Antisense oligonucleotides targeting ESE motifs selectively inhibited RAS(Q61) function, demonstrating therapeutic effects in vitro and in vivo.

Conclusions:

• The study uncovers a novel splicing-dependent mechanism for RAS(Q61K) oncogene activation.
• This research identifies a mutant-selective therapeutic strategy for RAS(Q61) cancers by targeting aberrant splicing.
• The findings suggest that exploiting splicing vulnerabilities could be a promising approach for treating other genetic-driven cancers.