N 6 -methyladenosine-modified SRPK1 promotes aerobic glycolysis of lung adenocarcinoma via PKM splicing.

BACKGROUND: The RNA N6 -methyladenosine (m6 A) modification has become an essential hotspot in epigenetic modulation. Serine-arginine protein kinase 1 (SRPK1) is associated with the pathogenesis of various cancers. However, the m6 A modification of SRPK1 and its association with the mechanism of in lung adenocarcinoma (LUAD) remains unclear.

METHODS: Western blotting and polymerase chain reaction (PCR) analyses were carried out to identify gene and protein expression. m6 A epitranscriptomic microarray was utilized to the assess m6 A profile. Loss and gain-of-function assays were carried out elucidate the impact of METTL3 and SRPK1 on LUAD glycolysis and tumorigenesis. RNA immunoprecipitation (RIP), m6 A RNA immunoprecipitation (MeRIP), and RNA stability tests were employed to elucidate the SRPK1's METTL3-mediated m6 A modification mechanism in LUAD. Metabolic quantification and co-immunoprecipitation assays were applied to investigate the molecular mechanism by which SRPK1 mediates LUAD metabolism.

RESULTS: The epitranscriptomic microarray assay revealed that SRPK1 could be hypermethylated and upregulated in LUAD. The main transmethylase METTL3 was upregulated and induced the aberrant high m6 A levels of SRPK1. Mechanistically, SRPK1's m6 A sites were directly methylated by METTL3, which also stabilized SRPK1 in an IGF2BP2-dependent manner. Methylated SRPK1 subsequently promoted LUAD progression through enhancing glycolysis. Further metabolic quantification, co-immunoprecipitation and western blot assays revealed that SRPK1 interacts with hnRNPA1, an important modulator of PKM splicing, and thus facilitates glycolysis by upregulating PKM2 in LUAD. Nevertheless, METTL3 inhibitor STM2457 can reverse the above effects in vitro and in vivo by suppressing SRPK1 and glycolysis in LUAD.

CONCLUSION: It was revealed that in LUAD, aberrantly expressed METTL3 upregulated SRPK1 levels via an m6 A-IGF2BP2-dependent mechanism. METTL3-induced SRPK1 fostered LUAD cell proliferation by enhancing glycolysis, and the small-molecule inhibitor STM2457 of METTL3 could be an alternative novel therapeutic strategy for individuals with LUAD.