Histone lactylation-driven YTHDF2 promotes non-small cell lung cancer cell glycolysis and stemness by recognizing m6A modification of SFRP2.

Histone lactylation is involved in non-small cell lung cancer (NSCLC) by transcriptional regulation of gene expression. YTH N6-methyladenosine RNA binding protein F2 (YTHDF2) is a N6-methyladenosine (m6A) "reader" that recognizes m6A methylation of mRNA and can be regulated by histone lactylation. This study aimed to investigate the role of histone lactylation in NSCLC and the underlying mechanism using in vitro experiments. Glycolysis and stemness were evaluated to assess cellular phenotypes. The effect of histone lactylation on YTHDF2 was evaluated by chromatin immunoprecipitation. The regulation of YTHDF2 on the downstream factor was assessed using RNA immunoprecipitation and dual-luciferase reporter analysis. The results showed that histone H3 lysine 18 lactylation (H3K18la) levels were increased in NSCLC tissues and cells. 2-deoxyglucose (2-DG) or sodium oxamate inhibited H3K18la, while Nala promoted H3K18la. Knockdown of lactate dehydrogenase A/B (LDHA and LDHB) suppressed glycolysis and cancer stemness in NSCLC cells. H3K18la was enriched in the promoter of YTHDF2, which was highly expressed in NSCLC. Knockdown of YTHDF2 suppressed NSCLC cell glycolysis and stemness, while its overexpression promoted the cellular behaviors. Moreover, YTHDF2 interacted with and recognized the m6A methylated secreted frizzled-related protein 2 (SFRP2), and knockdown of SFRP2 counteracted the inhibition of glycolysis and stemness. The animal experiments showed that YTHDF2 knockdown inhibited tumor growth and stemness by upregulating SFRP2 expression. In conclusion, histone lactylation transcriptionally activates YTHDF2 acts as an oncogene in NSCLC by promoting glycolysis and tumor stemness by recognizing m6A methylation of SFRP2. The findings suggest a novel epigenetic regulatory pathogenesis in NSCLC.