IGF2BP3-dependent N6-methyladenosine modification of USP49 promotes carboplatin resistance in retinoblastoma by enhancing autophagy via regulating the stabilization of SIRT1.

Abstract

Retinoblastoma (RB) poses significant challenges in clinical management due to the emergence of resistance to conventional chemotherapeutic agents, particularly carboplatin (CBP). In this study, we investigated the molecular mechanisms underlying CBP resistance in RB, with a focus on the role of autophagy and the influence of ubiquitin-specific peptidase 49 (USP49). We observed upregulation of USP49 in RB tissues and cell lines, correlating with disease progression. Functional assays revealed that USP49 promoted aggressive proliferation and conferred CBP resistance in RB cells. Furthermore, USP49 accelerated tumor growth and induced CBP resistance in vivo. Mechanistically, we found that USP49 facilitated CBP resistance by promoting autophagy activation. In addition, we identified insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3)-mediated N6-methyladenosine (m⁶A) modification of USP49 as a regulatory mechanism, wherein IGF2BP3 upregulated USP49 expression in an m⁶A-dependent manner. Moreover, USP49 stabilized SIRT1, a protein associated with CBP resistance and autophagy, by inhibiting its ubiquitination and degradation. Rescue experiments confirmed the pivotal role of SIRT1 in USP49-mediated CBP resistance. Our findings delineate a novel molecular network involving USP49-mediated autophagy in promoting CBP resistance in RB, offering potential targets for therapeutic intervention to enhance treatment efficacy and improve outcomes for RB patients.