A transcriptomic, proteomic, and functional genetic atlas dissects neurofibromin function in the peripheral nervous...

Area of Science:

• Oncology
• Molecular Biology
• Cancer Genetics

Background:

• The NF1 tumor suppressor gene (neurofibromin) regulates Ras signaling, and its mutation causes neurofibromatosis type 1 (NF-1) and associated cancers.
• Ras-MEK-ERK pathway activation due to NF1 loss drives tumor growth, leading to MEK inhibitor (selumetinib) approval for NF-1 related peripheral nervous system (PNS) tumors.
• The impact of NF1 loss on selumetinib sensitivity and alternative therapeutic targets remains incompletely understood.

Purpose of the Study:

• To systematically dissect the functional consequences of neurofibromin loss in peripheral nerve cells.
• To investigate the efficacy of targeting upstream or downstream components of the Ras pathway in NF1-mutant tumors.
• To identify novel therapeutic strategies for NF1-mutant PNS tumors.

Main Methods:

• CRISPR interference (CRISPRi) for gene repression in immortalized peripheral nerve (iPN) cells.
• RNA-sequencing and phosphoproteomic analyses to assess gene expression and signaling pathway activity.
• Pharmacologic inhibition and proximal proteomics to evaluate drug efficacy and protein interactions.

Main Results:

• NF1 repression in iPN cells increased Ras activity, promoted proliferation, and reduced sensitivity to selumetinib due to feedback regulation.
• PTPN11 repression had inverse effects, decreasing proliferation and increasing selumetinib sensitivity.
• SOS2 compensated for upstream inhibition of Son of Sevenless 1 (SOS1), limiting its efficacy.
• Proteomics identified KRAS, but not HRAS or NRAS, as the Ras isoform interacting with neurofibromin.

Conclusions:

• NF1 loss confers resistance to MEK inhibition via altered feedback mechanisms.
• Targeting KRAS, rather than MEK or SOS1, effectively inhibits ERK and CDK1/2 activation in NF1-mutant cells.
• KRAS inhibition represents a potential therapeutic strategy for NF1-mutant PNS tumors.