Abstract
Reprogramming metabolism is a hallmark of cancer cells for rapid progression. However, the detailed functional role of deubiquitinating enzymes (DUBs) in tumor glycolytic reprogramming is still unknown and requires further investigation. USP13 was found to upregulate in osteosarcoma (OS) specimens and promote OS progression through regulating aerobic glycolysis. Interestingly, the m(6)A writer protein, METTL3, has been identified as a novel target of USP13. USP13 interacts with, deubiquitinates, and therefore stabilizes METTL3 at K488 by removing K48-linked ubiquitin chains. Since METTL3 is a well-known m(6)A writer and USP13 stabilizes METTL3, we further found that USP13 increased global m(6)A abundance in OS cells. The results of RNA sequencing and methylated RNA immunoprecipitation sequencing indicated METTL3 could bind to m(6)A-modified ATG5 mRNA, which is crucial for autophagosome formation, and inhibit ATG5 mRNA decay on an IGF2BP3 dependent manner, thereby promoting autophagy and the autophagy-associated malignancy of OS. Using a small-molecule inhibitor named Spautin-1 to pharmacologically inhibit USP13 induced METTL3 degradation and exhibited significant therapeutic efficacy both in vitro and in vivo. Collectively, our study results indicate that USP13 promotes glycolysis and tumor progression in OS by stabilizing METTL3, thereby stabilizing ATG5 mRNA and facilitating autophagy in OS. Our findings demonstrate the role of the USP13-METTL3-ATG5 cascade in OS progression and show that USP13 is a crucial DUB for the stabilization of METTL3 and a promising therapeutic target for treating OS.