Abstract 2976: Targeting fibroblast growth factor (FGF) signals induced type I IFN regulated response and Immunogenic cell death (ICD) markers in tumor cells with activated FGF signals
Authors: Hoshi Taisuke , Kato Yu , Funahashi Yasuhiro 
Published: September 2020

Introduction: The FGF family plays key roles in many developmental and physiological processes. Aberrant activation of FGF signals (receptor mutations, fusions, and amplifications of ligands or receptors) have been reported, and considered to cause malignant cancers. Targeting FGFR suppresses proliferation and survival of tumor cells with activated FGF signal. However, the role of tumor FGFR inhibition in tumor microenvironments (TMEs) is largely still unknown. Lenvatinib (LEN) is a multi-targeted tyrosine kinase inhibitor that mainly inhibits VEGFR1-3 and FGFR1-4. Previously we showed that LEN inhibited tumor FGF signal, and induced cancer cell death, which had a role in antitumor activity. Here, we investigated roles of targeting tumor FGFR in TMEs using LEN or FGFR1-3 specific inhibitor E7090 in tumor cells with activated FGF signals.

Methods: To examine effects of FGF signal on gene expression profile (GEP) of tumor cells, mouse breast tumor 4T1 cell lines expressing Luc2 and AcGFP (4T1-Luc), human hepatocellular carcinoma (HCC) Hep3B2.1-7 and HuH-7 cells with FGF19 overexpression, and an endometrial cancer (EC) AN3CA cell line harboring FGFR2 mutation were treated with LEN or E7090. GEP was analyzed by RNA-Seq or qPCR in the 4T1-Luc model. Pathway enrichment analysis using RNA-Seq data was conducted by Ingenuity pathway analysis (IPA). Expression levels of type I IFN-related genes were analyzed in HCC and EC cell lines. Expressions of Cxcl10 and HMGB1 in culture supernatant were measured by ELISA. Cell surface expressions of PD-L1, MHC class I molecules and Calreticulin (CRT) were determined by flow cytometry.

Results: Unbiased pathway analysis using RNA-Seq data (fold change &gt;2 or &lt;0.5, TPM in NT-average &gt;1) from 4T1-Luc cells treated with LEN or E7090 identified Interferon (IFN) signal as one of the top 3 most significantly regulated pathways with several genes known to regulate tumor immunity. qPCR analysis showed that LEN and E7090 increased expression of type I IFN-related genes in human HCC and EC cell lines. LEN significantly increased CXCL10 in culture supernatant and expression of MHC class I and PD-L1 on cell surfaces of 4T1-Luc and Hep3B2.1-7 cells. E7090 also increased Cxcl10 in culture sup and expressions of MHC class I and PD-L1 on cell surface of 4T1-Luc cells. In addition to type I IFN-response, we found that LEN and E7090 might regulate ICD evidenced by increased expression levels of cell surface CRT, and Len increased secreted HMGB1 in culture sup of Hep3B2.1-7 cells.

Conclusion: Our results suggested that tumor FGF signals modulated immune response in TMEs through regulating interferon signal. Tumor FGF signal inhibition by LEN and E7090 may enhance antitumor immune response in the TMEs of that were immune suppressive with activated FGF signals. Further analyses will be warranted.

Citation Format: Taisuke Hoshi, Yu Kato, Yasuhiro Funahashi. Targeting fibroblast growth factor (FGF) signals induced type I IFN regulated response and Immunogenic cell death (ICD) markers in tumor cells with activated FGF signals [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2976.