Abstract: PURPOSE: To observe the expression level of histone lactylation modification in head and neck tumors and the effect of lactic acid on the proliferative ability of tumor cells. METHODS: Multicolor immunofluorescence was applied to detect the modification levels of PKLa and histone H3K9 lactylation (H3K9La) in 69 head and neck tumor tissues with tissue microarrays, and analyze their relationship with the clinical characteristics of the patients. Changes in the modification levels of PKLa, and H3K9La were detected by protein immunoblotting technology after head and neck tumor cells were stimulated by lactic acid. SPSS 17.0 software package was used for data analysis. RESULTS: PKLa modification levels were significantly higher in head and neck tumor tissues than in normal mucosal tissues. Analysis of clinical samples revealed that PKLa modification levels were significantly correlated with age and TNM stage(P<0.05), but not with gender, cervical lymph node metastasis, or pathological differentiation(P>0.05). Protein immunoblotting results demonstrated that histones were the main response proteins for lactylation modification in head and neck tumor cells, while lactic acid stimulation was able to increase the proliferation capacity of head and neck tumor cells. It was further determined that H3K9La modification in head and neck tumor cells had lactate-dependent up-regulation. Immunofluorescence staining also demonstrated higher levels of H3K9La in head and neck tumor tissues. CONCLUSIONS: Higher levels of histone lactate modification in head and neck tumor patients are potentially associated with head and neck tumor progression.

Key words: Head and neck tumors, Lactylation modification, Epigenetics, Post-translational modification