Mutation-specific effects of NRAS oncogenes in colorectal cancer cells

Area of Science:

• Oncology
• Molecular Biology
• Cancer Genetics

Background:

• NRAS mutations are less common than KRAS mutations in colorectal cancer (CRC).
• NRAS mutations emerge late in tumor progression and contribute to anti-EGFR therapy resistance in KRAS wild-type CRC.
• Understanding specific NRAS functions is crucial for targeted CRC therapies.

Purpose of the Study:

• To investigate the distinct functional consequences of NRAS G12D and NRAS Q61K mutations in CRC.
• To compare the cellular and molecular effects of NRAS mutations with KRAS mutations in a CRC model.
• To identify signaling pathways and phenotypes associated with NRAS mutations in CRC.

Main Methods:

• Utilized doxycycline-inducible NRAS G12D and NRAS Q61K mutations in the Caco-2 CRC cell line.
• Performed focused phospho-proteome analysis using the Bio-Plex platform to assess signaling pathway activity.
• Conducted transcriptome-wide RNA sequencing to identify gene expression and pathway alterations.

Main Results:

• Phospho-proteome analysis showed no significant differences in MAPK, PI3K, mTOR, STAT, p38, JNK, or ATF2 activity between NRAS and KRAS mutant cells.
• NRAS Q61K expression promoted anchorage-independent proliferation and tumorigenicity, mirroring KRAS-driven phenotypes.
• NRAS G12D expression led to reduced proliferation and increased apoptosis, alongside upregulated cytokine/chemokine secretion (IL1A, IL11, CXCL8, CCL20).
• RNA sequencing revealed activation of IL1, JAK/STAT, NFκB, and TNFα signaling pathways in NRAS G12D expressing cells.

Conclusions:

• NRAS mutations exert distinct functional effects in CRC, with NRAS Q61K mimicking canonical KRAS oncogenic roles.
• NRAS G12D promotes an inflammatory phenotype in CRC through the upregulation of specific cytokines and activation of inflammatory signaling pathways.
• These findings provide a basis for understanding NRAS-driven inflammation in CRC and suggest potential therapeutic strategies.