Histone H3k18 Lactylation Promotes Oral Carcinogenesis By Regulating Pyrimidine Metabolism

Metabolic reprogramming and epigenetic alterations promote oral squamous cell carcinoma (OSCC). Lactate-dependent histone modification is a new type of histone mark, which links glycolysis metabolite to the epigenetic process of lactylation. The objective was to evaluate the role of histone lactylation in oral carcinogenesis. The level of histone lactylation in dysplastic and cancer tissues was identified by immunohistochemistry. The participation of histone lactylation in OSCC initiation was confirmed through inhibition of histone lactylation by glycolysis inhibitors or lactate dehydrogenase A (LDHA) knockdown both in vitro and in vivo. RNA-seq, metabolomics analysis, and CUT&Tag were performed to investigate the mechanism of H3K18 lactylation (H3K18la). The candidate target genes were validated through RT-qPCR, western blot and ChIP-qPCR analyses. Next, the effects of these genes in oral carcinogenesis were confirmed by knockdown or overexpression. Histone lactylation, especially H3K18la level was elevated in dysplastic and cancer tissues. The suppression of glycolytic activity by different kinds of inhibitors or LDHA knockdown decreased cell proliferation and induced cell cycle arrest in vitro. Glycolysis inhibitors blocked the formation of precancerous lesion and OSCC in 4NQO-induced tongue carcinogenesis model. Mechanistically, H3K18la was enriched at the promoters and activated the transcription of ribonucleotide reductase subunits M1 and M2, resulting in alleviation of replication stress. We reveal that H3K18la may play a vital role in blockage of oral carcinogenesis, thereby providing novel therapeutic targets for OSCC therapy. These findings bridge histone modifications with nucleotide metabolism, which provides novel understanding of epigenetic regulation in carcinogenesis.