FTO triggers NLRP3/GSDMD-dependent pyroptosis to enhance cisplatin-sensitivity in ovarian cancer

Chemotherapy resistance is still the major impediment to poor prognosis of ovarian cancer (OC). The fat mass and obesity associated protein (FTO), as the first recognized RNA N6-methyladenosine (m6A) demethylase, was dysregulated in various tumors, but its effect on chemoresistance of OC remains unexplored. In this study, FTO expression in tissues and cells was measured by qPCR, IHC, and Western blot. Functional assays were performed, including CCK-8, colony formation, flow cytometry, Transwell assays, and LDH release. Pyroptosis-related proteins were detected by Western blot. MeRIP-qPCR was conducted to measure the m6A level. Finally, the effect of FTO on tumor growth and cisplatin (DDP) sensitivity of OC was checked in a mouse model. We found that FTO was significantly downregulated in OC tissues compared to adjacent normal tissues. In addition, the protein level of FTO was much lower in cisplatin (DDP)-resistant cells than in DDP-sensitive cells. Then, FTO overexpression in DDP-resistant cells decreased IC50 of DDP, increased cell apoptosis, and inhibited cell proliferation, migration, and invasion, whereas FTO silencing cells showed the opposite phenotypes. Moreover, FTO promoted the protein expressions of pyroptosis-related proteins, including NLRP3, cleaved-caspase-1, and GSDMD-NT, to enhance DDP sensitivity, as indicated by lower IC50. Furthermore, FTO activated NLRP3/ Caspase-1/GSDMD-mediated pyroptosis in DDP-resistant cells. Mechanically, FTO successfully reduced the total m6A level and NLRP3 mRNA m6A modification to further increase DDP sensitivity in resistant cells. Finally, FTO overexpression promoted DDP-sensitivity and NLRP3 expression to inhibit tumorigenesis in a nude mice xenograft model. Together, our study inferred that FTO triggered NLRP3/Caspase-1/GSDMD-dependent pyroptosis by mediating NLRP3 m6A demethylation to enhance DDP-sensitivity and inhibit the progression of OC. This project indicates that FTO overexpression may be a potential strategy to overcome DDP resistance in OC.