Cancer-associated fibroblasts potentiate colorectal cancer progression by crosstalk of the IGF2-IGF1R and Hippo-YAP1 signaling pathways.

Colorectal cancer (CRC) is one of the most common cancers worldwide. The tumor microenvironment exerts crucial effects in driving CRC progression. Cancer-associated fibroblasts (CAFs) serve as one of the most important tumor microenvironment components promoting CRC progression. The study aimed to elucidate the novel molecular mechanisms of CAF-secreted IGF2 in colorectal carcinogenesis. Our results indicated that IGF2 was a prominent factor upregulated in CAFs compared with normal fibroblasts. CAF-derived conditioned media (CM) promoted tumor growth, migration, and invasion of HCT 116 and DLD-1 cells. IGF1R expression is significantly increased in CRC, serving as a potent receptor in response to IGF2 stimulation and predicting unfavorable outcomes of CRC patients. Apart from the PI3K-AKT pathway, RNA-seq analysis revealed that the YAP1-target signature serves as a prominent downstream effector to mediate the oncogenic signaling of IGF2-IGF1R. By single-cell RNA sequencing (scRNA-seq) and immunohistochemical validation, IGF2 was found predominantly secreted by CAFs, whereas IGF1R was expressed mainly by cancer cells. IGF2 triggers nuclear accumulation of YAP1 and upregulates YAP1 target signatures, however, these effects were abolished by either IGF1R knockdown or inhibition with PPP (picropodophyllin, an IGF1R inhibitor). Using CRC organoid and in vivo studies, we found that co-targeting IGF1R and YAP1 with PPP and VP (verteporfin, a YAP1 inhibitor) enhanced anti-tumor effects compared with PPP treatment alone. In conclusion, this study revealed a novel molecular mechanism by which CAFs promote CRC progression. The findings highlight the translational potential of the IGF2-IGF1R-YAP1 axis as a prognostic biomarker and therapeutic target for CRC. This article is protected by copyright. All rights reserved.