Overexpression of KRAS-Q25A mutant with enhanced GTPase activity inhibits the progression of KRAS-G12D colorectal cancer

Oncogenic KRAS mutations occur in approximately 40% of colorectal cancer (CRC) cases and correlate with poor prognosis. While restoring GTP hydrolysis in KRAS-mutant tumors represents a promising therapeutic strategy, its mechanistic basis remains unclear. KRAS Q25A mutant exhibits enhanced intrinsic GTPase activity, but its cellular impact is unknown. Here, we investigated the tumor-suppressive effects of KRAS Q25A in KRAS G12D -mutant CRC. Transfection of the KRAS Q25A mutant inhibited the proliferation, migration and adhesion of KRAS G12D -mutant CRC cell lines, concomitant with reduced active RAS level and attenuated MAPK activation. Co-mutation with A59G reversed these effects. RNA sequencing revealed that upregulated genes in the KRAS Q25A -expressing group were associated with the TGF-β pathway and negative regulation of cell proliferation, while downregulated genes were linked to cholesterol metabolism pathways and integrin-mediated adhesion. In vivo, KRAS Q25A -expressing tumors exhibited slower growth versus controls. In conclusion, our study shows that KRAS Q25A suppresses KRAS G12D -driven CRC progression by lowering active RAS levels, dependent on its enhanced GTPase activity. These findings provide insights into KRAS function and offer potential leads for developing therapies targeting KRAS-mutated CRC.