Abstract:

Background/aim: The aberrant upregulation of Forkhead box protein M1 (FOXM1) plays a fundamental role in cancer initiation by perturbing stem cell differentiation. This study aims to investigate the role of FOXM1 in epigenetic modification and gene expression of target genes in primary human oral keratinocytes, squamous cell carcinoma cell lines, and head and neck squamous cell carcinoma (HNSCC) tissue biopsies. Materials and methods: A genome-wide promoter methylation microarray was used to compare HNSCC cell line (n = 8), primary human oral keratinocytes (NOK; n = 8) transduced with FOXM1 and EGFP, and HNSCC tissue biopsies (n = 3). Seventeen Foxm1B-induced differentially methylated genes were shortlisted. An absolute quantitative polymerase chain reaction was used to validate the differential promoter DNA methylation of each candidate gene induced by FOXM1. These results were compared with the methylation status and altered gene expressions of candidate genes in a panel of genomic DNA and messenger RNA (mRNA) samples previously extracted from HNSCC tissue biopsies. Results: The results were consistent with our hypothesis, showing that aberrant upregulation of FOXM1 expression in in vitro primary NOK induces a global hypomethylation pattern similar to the HNSCC cell line and has an inverse correlation with in vivo mRNA expression levels of HNSCC tissue biopsy. Conclusion: Such epigenetic changes have tremendous clinical potential as biomarkers for early cancer detection and therapeutic interventions

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