Lactylome analyses suggest systematic lysine- lactylated substrates in oral squamous cell carcinoma under normoxia and hypoxia

Abstract

Abstract Background Intracellular lactate is shown to drive a novel type of post-translational modification (PTM), lysine lactylation (Kla), which has been confirmed to affect the malignant progression of tumors such as hepatocellular carcinoma (HCC) and gastric cancer. However, the systemic lactylome profiling of oral squamous cell carcinoma (OSCC) is still unclear.Methods In this study, we utilized liquid chromatography-tandem mass spectrometry (LC-MS/MS) to conduct the quantitative lactylome analyses in OSCC cell line under normoxia and hypoxia. Then, bioinformatics analyses were applied to reveal the conserved motif sequences and enrichment pathways. What’s more, Immunoprecipitation and western blotting verified the results of lactylome.Results The integrative lactylome and proteome analyses identified 1011 Kla sites within 532 proteins and 1197 Kla sites within 608 proteins in SCC25 cells under normoxic and hypoxic environments, respectively. Among these lactylated proteins, histones accounted for only a small fraction, suggesting the presence of Kla modification in large number of non-histones proteins. Notably, Kla prefers to enrich in spliceosome, ribosome and glycolysis/gluconeogenesis pathway in both normoxic and hypoxic cultures. Compared with normoxia, 231 differentially lactylated proteins with 334 differentially lactylated sites were detected under hypoxia, which were mainly associated with glycolysis/gluconeogenesis pathway by KEGG analysis. Importantly, we verified the presence of lactylation in spliceosomal proteins SF3A1 and hnRNPA1 as well as the glycolytic enzyme PFKP.Conclusion Our study is the first report to elucidate the lactylome and its biological function in OSCC, which deepens our understanding of the mechanisms underlying OSCC progression and provides a novel strategy for targeted therapy for OSCC.