HOXD10 expression in oral cancer is driven by histone acetylation rather than promoter DNA methylation

OBJECTIVE: HOXD10 is implicated in the carcinogenesis and progression of various cancers, including oral cancer. However, its regulatory mechanism and functional role remain unclear. DESIGN: Matched normal and oral cancer tissue samples from patients stratified into oral potentially malignant disorders (OPMD, n = 25), lymph-node negative (LN(-), n = 25), and lymph-node positive (LN(+), n = 25) groups were analysed along with a panel of oral cancer cell lines. Expression was quantified by qRT-PCR and DNA methylation was profiled by methyl-capture sequencing followed by correlation analysis with expression. The DNA methyltransferase inhibitor(DNMTi): Decitabine(5-Aza-CdR) and histone deacetylase inhibitors(HDACi) - suberoylanilide hydroxamic acid(SAHA) and sodium butyrate(NaB) were used to evaluate epigenetic regulation in SCC9 cells. Promoter regions were characterized by dual luciferase assay and sodium butyrate effects on cell proliferation, migration and cell cycle were assessed. RESULTS: HOXD10 was significantly upregulated in OPMD and LN(+) groups and oral cancer cell lines but not in the LN(-) samples or across cancer stages/grades compared with normal controls. Promoter hypermethylation correlated positively, though not significantly, with expression. 5-Aza-CdR treatment did not alter HOXD10 levels, while HDACi treatment reduced expression. Two promoter regions were identified as active regulatory elements modulated by histone acetylation. Functionally, NaB impaired cell proliferation, migration and induced G2-M arrest. Survival analysis demonstrated modest prognostic value of HOXD10 alone but improved predictive accuracy for disease recurrence when integrated with tumor stage and grade. CONCLUSION: HOXD10 expression in oral cancer is regulated predominantly via histone acetylation. These findings highlight its epigenetic regulation and suggest potential clinical relevance with tumor stage and grade although further studies are needed to confirm diagnostic or prognostic value.