Fig 2: CAFs-secreted FGF5 inhibits ferroptosis caused by DDP via regulating Keap1/Nrf2/HO-1 pathway in NPC cells.A The mRNA level of Nrf2 in transfected NPC cells were detected by qRT-PCR. NPC/HK1 and C666-1 cells were divided into six groups: control, DDP (5 μg/mL), DDP (5 μg/mL) + Vector-CM, DDP (5 μg/mL)+FGF5-CM, DDP (5 μg/mL)+FGF5-CM+shNC and DDP (5 μg/mL) + FGF5-CM + shNrf2#2. B The protein levels of Keap1, Nrf2 and HO-1 in NPC cells were detected by western blot. C Cell viability was monitored by CCK-8 assay. D–F The levels of MDA (D), Fe2+ (E) and GSH (F) in NPC cells were measured using commercial kits. G NPC cells were stained with BODIPY C11 and lipid peroxidation was assessed by flow cytometry. H The protein levels of GPX4 and SLC7A11 were detected by western blot. *P < 0.05, **P < 0.01, and ***P < 0.001.

Fig 3: CAFs-secreted FGF5 binds to FGFR2 in NPC cells directly.A The interactions between FGF5 and FGFRs in NPC tissues were detected by Co-IP assay. B The mRNA level of FGFR2 in N69, NPC/HK1 and C666-1 cells was detected by qRT-PCR. C The protein level of FGFR2 in N69, NPC/HK1 and C666-1 cells was detected by western blot. D The expression of FGFR2 in nasal polyp and NPC tissues was determined by tissue microarray. The first column: nasal polyp tissues. 2–9 columns: NPC tissues. E The immunoreactivities of FGF5 and FGFR2 in NPC tissues were detected by IHC analysis. Scale bar: 20 μm. *P < 0.05 and ***P < 0.001.

Fig 4: CAFs inhibit DDP-induced ferroptosis via secreting FGF5.Human CAFs and NFs were isolated from NPC tissues and the adjacent normal tissues, respectively. A The expression levels of α-SMA and FAP in CAFs were detected by immunofluorescence. Green, α-SMA. Red, FAP. Blue, DAPI. Scale bar: 100 μm. B The protein levels of α-SMA, vimentin and FAP in NFs and CAFs were detected by western blot. C The protein level of FGF5 in fibroblasts was detected by western blot. D The secretion of FGF5 in fibroblasts was assessed by ELISA assay. NPC/HK1 and C666-1 cells were divided into following groups: control, DDP (5 μg/mL), DDP (5 μg/mL)+CM and DDP (5 μg/mL)+anti-FGF5 antibody. E Cell viability was monitored by CCK-8 assay. F The protein levels of GPX4 and SLC7A11 were detected by western blot. G–I The levels of MDA (G), Fe2+ (H) and GSH (I) in NPC cells were measured using commercial kits. J NPC cells were stained with BODIPY C11 and lipid peroxidation was assessed by flow cytometry. *P < 0.05, **P < 0.01, and ***P < 0.001.

Fig 5: CAFs inhibit DDP-induced ferroptosis via FGF5/FGFR2 axis.A The mRNA level of FGFR2 in transfected NPC cells were detected by qRT-PCR. B The protein level of FGFR2 in transfected NPC cells were detected by western blot. NPC/HK1 and C666-1 cells were divided into five groups: control, DDP (5 μg/mL), DDP (5 μg/mL)+FGF5-CM, DDP (5 μg/mL) + FGF5-CM + shNC and DDP (5 μg/mL) + FGF5-CM + shFGFR2#1. C The protein levels of FGFR2, Keap1, Nrf2 and HO-1 in NPC cells were detected by western blot. D Cell viability was monitored by CCK-8 assay. E–G The levels of MDA (E), Fe2+ (F) and GSH (G) in NPC cells were measured using commercial kits. H NPC cells were stained with BODIPY C11 and lipid peroxidation was assessed by flow cytometry. *P < 0.05, **P < 0.01, and ***P < 0.001.