IGF2BP3/m6A-mediated intron retention isoform of DUSP6 promotes cisplatin resistance in nasopharyngeal carcinoma by inhibiting pyroptosis

BACKGROUND: Nasopharyngeal carcinoma (NPC) is a complicated pathological cancer, which has a close association with pyroptosis and abnormal alternative splicing (AS). However, the molecular changes and functions of AS-mediated pyroptosis in cisplatin-resistant NPC cells remain poorly understood. METHODS: The expression patterns of different splicing isomers of dual-specificity phosphatase 6 (DUSP6) were evaluated by semi-quantitative PCR. The effects of DUSP6 knockdown on cisplatin sensitivity and pyroptosis in NPC were examined by CCK-8 assay, immunofluorescence and ELISA. The occurrence mechanism of DUSP6 AS was explored by RNA pull down, mass spectrometry and MeRIP-PCR. RESULTS: DUSP6 underwent AS, among which the intron retention isoform DUSp6-IR1 increased in expression dependent on the dose and time of cisplatin. Knockdown of DUSP6-IR1 significantly suppressed viability and cisplatin resistance and promoted apoptosis of C666-1 cells upon cisplatin treatment. In vivo, sh-DUSP6-IR1 reduced the weight and volume of tumors. While DUSP6-IR1 knockdown in C666-1 cells enhanced pyroptosis (evidenced by elevated LDH release, Gasdermin D (GSDMD)/NOD-like receptor thermal protein domain associated protein 3 (NLRP3) expression, and IL-18/IL-1β levels, along with reduced cell viability), these effects were reversed by a pyroptosis inhibitor. The m6A reader protein insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) enhanced the splicing generation of the DUSP6-IR1 isoform through its KH3-4 domains, thereby suppressing pyroptosis in NPC cells and ultimately conferring cisplatin resistance. CONCLUSIONS: These findings revealed a promising novel direction to investigate cisplatin resistance and suggested potential therapeutic target for overcoming chemotherapy resistance in NPC.