The Functional Proximal Proteome of Oncogenic Ras Includes mTORC2

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• Difficult-to-drug oncogenes like Ras drive many cancers.
• Identifying novel Ras pathway interactors is crucial for therapeutic development.

Purpose of the Study:

• To identify novel proteins associated with Ras isoforms using proximity-dependent biotin labeling (BioID).
• To determine the functional role of identified proteins in Ras-driven cancers.
• To define new therapeutic strategies targeting the Ras pathway.

Main Methods:

• Proximity-dependent biotin labeling (BioID) was employed with wild-type and mutant Ras isoforms (H-, K-, and N-Ras).
• CRISPR screening was used to identify Ras-dependent proteins from BioID-identified interactors.
• Biochemical assays and in vivo models were utilized to validate Ras-mTORC2 interactions and their functional consequences.

Main Results:

• BioID identified 130 novel proteins proximal to all Ras isoforms, including known interactors Raf and PI3K.
• CRISPR screening identified mTOR as a key Ras-dependent protein, also found proximal to mutant Ras in human tumors.
• Oncogenic Ras directly binds mTOR and MAPKAP1, activating mTORC2 kinase activity and promoting the Ras pro-proliferative cell cycle program.
• Disrupting the Ras-mTORC2 interaction impaired Ras-dependent neoplasia in vivo.

Conclusions:

• mTORC2 is a novel, direct effector of oncogenic Ras.
• The Ras-mTORC2 axis is critical for Ras-driven cancer cell proliferation and tumor development.
• Combining BioID with CRISPR screening is an effective strategy for discovering functional interactors of dominant oncogenes.