Abstract 898: Metformin and ICG-001 act synergistically to abrogate cancer stem cell-mediated chemoresistance in colorectal cancer by promoting apoptosis and autophagy
Authors: Roy Souvick , Zhao Yinghui , Yuan Yate-Ching , Goel Ajay 
Published: June 2022

Background: Colorectal cancer (CRC) remains the third most frequently diagnosed cancers in the United States. Current treatment modalities for patients with CRC include surgery, which is often followed with 5-fluorouracil (5FU) based adjuvant chemotherapy. While such treatment regimens are effective at improving disease outcomes, their clinical usefulness is often hampered due to emergence of chemotherapeutic resistance. Presence of cancer stem cells (CSCs) have been attributed towards 5FU-mediated drug resistance which subsequently leads to poor prognosis in CRC patients. In this study we investigated a novel therapeutic strategy by using metformin along with ICG-001, a Wnt signaling inhibitor, as an approach to abrogate CSC mediated chemoresistance in 5FU resistant (5FUR) and parental CRC cells, as well as CRC patient derived tumor organoids.

Methods: Two 5FU resistant (5FUR)-CRC cell lines previously generated and characterized in our lab were used in this study. First, we performed genome-wide transcriptomic profiling followed by pathway enrichment analysis to identify differentially expressed genes and its associated pathways between parental and 5FUR CRC cells. Next, we determine the anti-tumor effects of metformin and ICG-001 by performing cell viability, colony formation, migration, and invasion analysis. Next, we explore the possible mechanism of action of these two drugs by performing gene and protein expression analysis of CSC, autophagy and apoptotic markers. We also evaluated the anti-tumor activity of metformin and ICG-001 in CRC patient derived tumor organoids.

Results: We observed that 5FUR-CRC cells exhibited increased expression of CSC markers and increased spheroid forming ability. Genome-wide transcriptomic analysis followed by pathway analysis revealed that Wnt signaling pathway, pathways regulating pluripotency of stem cells etc. were enriched between parental and 5FUR CRC cells. These findings prompted us to use ICG-001 which selectively targets Wnt signaling along with metformin in abrogating CSC mediated chemoresistance in CRC. We observed that a combined treatment of metformin and ICG-001 exert anti-tumor activity in by decreasing cell viability (p&lt;0.01), colony formation (p&lt;0.001), migration (p&lt;0.01), and invasion ability (p&lt;0.01) in synergistic manner. We also observed that combined treatment decreases the expression of CSC markers and promote autophagy and apoptosis. In accordance with our in vitro studies, we observed that metformin and ICG-001 exhibited anti-tumor activity in patient derived CRC organoid models in combination (p&lt;0.001).

Conclusion: We conclude that metformin and ICG-001 act synergistically, which can be used as a therapeutic strategy to overcome 5FU mediated therapeutic resistance in CRC.

Citation Format: Souvick Roy, Yinghui Zhao, Yate-Ching Yuan, Ajay Goel. Metformin and ICG-001 act synergistically to abrogate cancer stem cell-mediated chemoresistance in colorectal cancer by promoting apoptosis and autophagy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 898.