Single Synonymous Mutations in KRAS Cause Transformed Phenotypes in NIH3T3 Cells

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Synonymous mutations in cancer driver genes, like KRAS, are increasingly recognized.
• Specific mutations at glycine residues G12, G13, and G60 in KRAS are common in human cancers.

Purpose of the Study:

• To investigate the functional impact of synonymous mutations at KRAS codons G12, G13, and G60.
• To determine if these mutations contribute to cancer-associated phenotypes.

Main Methods:

• Generated NIH3T3 cell lines expressing wild-type KRAS and KRAS with synonymous mutations at G12, G13, and G60.
• Assessed KRAS protein expression, cell proliferation, density, invasiveness, and contact inhibition.
• Evaluated the effect of trametinib on cell refractility.

Main Results:

• All synonymous KRAS mutant cell lines showed increased KRAS protein expression, faster growth, higher densities, and enhanced invasiveness compared to wild-type.
• Three mutant cell lines exhibited significant loss of contact inhibition and increased refractility, which was reduced by trametinib.
• Highly conserved codon usage at these glycine sites suggests selective pressure.

Conclusions:

• Synonymous mutations in KRAS can induce oncogenic phenotypes, including increased proliferation and invasiveness.
• These findings highlight the potential role of synonymous mutations in driver genes as contributors to human cancer.
• Targeting pathways affected by these mutations, such as MEK (inhibited by trametinib), may be relevant in cancers with these KRAS alterations.