RAS inhibitors modulate Wnt signaling in CRC

Introduction: RAS mutations are a common feature of colorectal cancer (CRC) and are associated with intrinsic drug resistance to anti-EGFR therapy, posing a significant clinical challenge that limits therapeutic efficacy.

Aims: This study aims to elucidate potential Wnt-dependent resistance mechanisms to pan-KRAS/RAS inhibitors (KRASi) and to evaluate the therapeutic potential of combined Wnt/KRAS inhibition in CRC.

Methods: We employed of novel pan-KRAS inhibitors to assess Wnt signaling activation across various CRC models, including CRC cell lines, patient-derived organoids (PDOs), and mouse-derived intestinal tumor organoids (MDOs). Expression of candidate Wnt-related genes was measured by quantitative PCR and western blot analysis. To further confirm Wnt pathway induction following KRASi, we performed RNA interference (RNAi) assays and Wnt reporter assays. Viability effects of KRASi in cell lines and organoids were confirmed by CellTitre Glo assay or by immunofluorescence microscopy.

Results: Cell viability assays conducted in CRC cell lines demonstrated a dose-dependent and time-dependent reduction in cell proliferation following treatment with pan-KRAS/RAS inhibitors, indicative of their antineoplastic potential. Consistently, patient-derived organoids (PDOs) exhibited a decrease in proliferative capacity, as evidenced by diminished Ki67 immunofluorescence staining, further supporting the efficacy of KRASi in suppressing tumor growth. To elucidate the molecular response to KRASi, we determined expression of Wnt and intestinal stemness related genes in CRC cell lines, PDOs and MDOs with genetically defined mutational backgrounds. These analyses consistently revealed upregulation of the Wnt related targets following KRASi. We confirmed these results by Wnt reporter assays in multiple cell lines, showing an induction of the reporter activity upon KRASi. RNA interference-based depletion of KRAS expression independently confirmed activation of Wnt signaling. These findings collectively suggest that Wnt pathway activation is an adaptive response to KRAS inhibition, potentially serving as a resistance mechanism to KRASi in CRC.

Conclusion: Our findings highlight the extensive crosstalk between Ras-MAPK and Wnt signaling pathways in CRC. This study provides novel insights into overcoming intrinsic drug resistance in KRAS-mutant CRC and suggests a therapeutic potential for dual Wnt/KRAS inhibition.

Publication History

Article published online:
04 September 2025