Abstract 727: FGFR4 promotes colon cancer progression through CAF activation via the CXCL10-CXCR3 axis
Authors: Cho Sang-Hee , Bang Hyunjin , Sun Eun-Gene , Choi Ji-Na , Park Mi-Ra , Shim Hyun-Jeong , Hwang Jun-Eul , Bae Woo-Kyun , Chung Ik Joo 
Published: March 2024

Abstract
Cancer-associated fibroblasts (CAFs) contribute to cancer progression via crosstalk with cancer and immune cells in the tumor microenvironment (TME). Despite the significant role of CAF, the understanding of the trigger mechanisms of cancer-mediated CAF activation remains unclear. We previously reported the mechanism by which FGFR4 in colon cancer secretes amphiregulin (AREG), resulting in anti-EGFR chemoresistance. It motivated us to investigate whether FGFR4 overexpressing tumors may change the TME, so we explored the mechanism of CAF activation under the FGFR4 signaling pathway. CAF was isolated from BALB/C mice after injecting 1 × 106 CT-26/EV or FGFR4 cells using microbeads and conditioned media (CM) was prepared by filtering after 48h cancer cell culture with serum-free medium In mice model, CT-26/FGFR4 showed more significant tumor progression and CAF abundance (α-SMA, FAP, PDGFR, and vimentin) than CT-26/EV. Additionally, CT26/FGFR4-derived CAFs showed significantly increased invasiveness and contractility, indicating the highly activated status of CAFs. In order to verify the effect of cancer secretome from FGFR4 in cancer cells, normal fibroblast (NIH/3T3) were co-cultured with either stable cancer cells or CM. As a result, CT-26/FGFR4 cells robustly induced the expression of CAF markers in NIH/3T3 cells, indicating the promotion of CAF differentiation from resting fibroblasts. Also, CT-26/FGFR4-derived CM significantly promoted further activation of CAFs compared to CT-26/EV-derived CM. Taken together, FGFR4 contributes not only to CAF differentiation but also to CAF activation via secretome. Next, we performed RNA seq of CT-26/EV and CT-26/FGFR4 cells and identified the upregulated genes related with the interferon (IFN) signaling. Among these genes, we identified IFNβ and CXCL10 as targetable molecules via the activation of TLR3-TBK-IRF and IFN-STAT-CXCL10 signaling pathways. These results were confirmed by RT-PCR and western blot assay. Secreted CXCL10 induced gene expression of CAF markers in fibroblast and increased CAF functions such as migration, invasion and contractibility, reflecting CAF activation. Blocking antibodies and knocking down of CXCL10 inhibited the cancer secretome-mediated CAF markers. The blockade of CXCR3, which is the CXCL10 cognate receptor, also showed an inhibitory effect on the FGFR4-overexpressing cancer-educated CAF. In human colon cancer specimens, the expression of FGFR4, CXCL10, and CAF markers showed a positive correlation with each other. Finally, dual inhibition of FGFR4 and CXCR3 in tumor mouse model suppressed the tumor growth, accompanied by CAF suppression. Our findings reveal the novel mechanism of FGFR4 leading CAF differentiation/activation in TME via the CXCL10-CXCR3 axis. This suggests that FGFR4/CXCR3 inhibitor could be used as a potential therapeutic strategy to attenuate CAF in stromal dominant tumors.
Citation Format: Sang-Hee Cho, Hyunjin Bang, Eun-Gene Sun, Ji-Na Choi, Mi-Ra Park, Hyun-Jeong Shim, Jun-Eul Hwang, Woo-Kyun Bae, Ik Joo Chung. FGFR4 promotes colon cancer progression through CAF activation via the CXCL10-CXCR3 axis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 727.