SOS1
Overview
SOS1 (Son of Sevenless Homolog 1) encodes a RAS guanine nucleotide exchange factor (GEF) that activates RAS by catalyzing GDP-to-GTP exchange. Gain-of-function mutations in SOS1 can constitutively activate the RAS/MAPK pathway without upstream RTK activation. In lung adenocarcinoma, SOS1 is a candidate driver in “oncogene-negative” tumors that lack established RTK/RAS/RAF alterations.
Alterations observed in the corpus
- Recurrent autoinhibitory-domain mutation p.N233Y (n=4) significantly enriched among oncogene-negative lung ADC tumors lacking known RTK/Ras/Raf activating events (q < 0.1); identified in a 660-ADC exome-sequencing cohort PMID:27158780.
- Adding SOS1 along with VAV1, RASA1, and ARHGAP35 raised the proportion of lung ADCs with a candidate Ras/Raf/RTK pathway driver to 76% overall and 85% in an expert-reviewed subset PMID:27158780.
Cancer types (linked)
- LUAD: Candidate Ras-pathway driver in oncogene-negative lung ADC; recurrent p.N233Y mutation in the autoinhibitory domain, n=4 cases in 660-tumor cohort PMID:27158780.
Co-occurrence and mutual exclusivity
- Enriched in tumors lacking established RTK/Ras/Raf activating alterations (e.g., EGFR mutations, ALK fusions, KRAS mutations), suggesting mutual exclusivity with canonical oncogene drivers PMID:27158780.
Therapeutic relevance
- SOS1 inhibitors (e.g., BI-1701963) have entered clinical evaluation for KRAS-mutant cancers; by extension, SOS1 gain-of-function mutations in oncogene-negative LUAD represent a candidate therapeutic vulnerability, though this was not directly tested in the citing study PMID:27158780.
Open questions
- Functional validation of p.N233Y as a gain-of-function mutation in vivo in lung cancer context was not performed in the citing study PMID:27158780.
Sources
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