2542 - FGFR3 Mediates Radioresistance in Non-Small Cell Lung Cancer through Reprogramming of Fatty Acid Metabolism
Presenter(s)
R. Zhang1, M. Jiang2, J. Yu3, and D. Chen4; 1Shandong University Cancer Center;Department of Radiation Oncology and Shandong Provincial Key Laboratory of Radiation Oncology, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China, 2Department of Radiation Oncology and Shandong Provincial Key Laboratory of Precision Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, China, Jinan, Shandong, China, 3Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences Department of Radiation Oncology, Jinan, Shandong, China, 4Department of Radiation Oncology and Shandong Provincial Key Laboratory of Precision Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
Purpose/Objective(s): FGFR3-mediated radioresistance in NSCLC involves complex signaling pathways and tumor microenvironment interactions, yet its precise mechanisms remain unclear. This study explores FGFR3-associated downstream signaling and upstream ligands to identify potential therapeutic targets for enhancing radiosensitivity.
Materials/Methods: Co-Immunoprecipitation Mass Spectrometry (Co-IP-MS) was initially employed to identify the interaction between FGFR3 and Fibulin-5. The binding of Fibulin-5 to FGFR3 was confirmed in vitro using an HEK293T overexpression system and co-immunoprecipitation (Co-IP) assays, and molecular docking further validated their interaction. Given that Fibulin-5 is primarily secreted by cancer-associated fibroblasts (CAFs) in the TME, we verified the endogenous binding of CAF-derived Fibulin-5 to FGFR3 in a co-culture system of CAFs and tumor cells. In vitro CAFs-cancer cell co-culture experiments and a subcutaneous tumor radiotherapy model in mice demonstrated that Fibulin-5 significantly enhanced NSCLC radioresistance by activating FGFR3. RNA sequencing (RNA-seq) was performed on FGFR3-knockdown NSCLC cells to explore downstream molecular mechanisms, which were further validated at both cellular and animal levels. Fatty acid metabolic reprogramming was assessed through lipid staining and imaging experiments, as well as Seahorse energy metabolism analysis. Finally, multiplex immunofluorescence staining of pre-radiotherapy biopsy tissues from NSCLC patients (n=79) was conducted, and the clinical relevance of key molecules to radiotherapy efficacy was evaluated.
Results: Endogenous binding between FGFR3 on cancer cell surfaces and CAFs-derived Fibulin-5 was observed. Fibulin-5 secreted by CAFs directly binds to FGFR3, activating STAT3 and downregulating PGC1A, leading to enhanced fatty acid synthesis (FASN?, lipid droplet accumulation) and suppressed oxidation (PGC-1a?, reduced OCR), thereby mediating fatty acid metabolic reprogramming and promoting radiotherapy resistance. Additionally, multiplex immunofluorescence analysis of tissue samples from radioresistant and sensitive NSCLC patients confirmed the clinical relevance of Fibulin-5, FGFR3, and PGC-1a to radiotherapy efficacy.
Conclusion: Under radiotherapy conditions, activated fibroblasts regulate the FGFR3-STAT3-PGC1A signaling axis in cancer cells through the overexpression of the secreted protein Fibulin-5, inducing fatty acid metabolic reprogramming and significantly enhancing NSCLC radiotherapy resistance. This study identifies Fibulin-5 as a novel ligand for the membrane protein FGFR3, providing a theoretical basis for improving tumor cell radiosensitivity by targeting CAFs-cancer cell interaction-mediated metabolic remodeling. It also suggests potential strategies for combined targeting of FGFR3 or metabolic pathways.