Genome-Wide DNA Methylation Confirms Oral Squamous Cell Carcinomas in Proliferative Verrucous Leukoplakia as a Distinct Oral Cancer Subtype: A Case-Control Study.

Abstract

Background/objectives: Oral cancers in patients with proliferative verrucous leukoplakia (PVL-OSCC) exhibit different clinical and prognostic outcomes from those seen in conventional oral squamous cell carcinomas (cOSSCs). The aim of the present study is to compare the genome-wide DNA methylation signatures in fresh frozen tissues between oral squamous cell carcinomas in patients with PVL and cOSCC using the Illumina Infinium MethylationEPIC BeadChip.

Methods: This case-control study was carried out at the Stomatology and Maxillofacial Surgery Department of the General University Hospital of Valencia. For the epigenomic study, unsupervised exploratory bioinformatic analyses were performed using principal component and heatmap analysis. Supervised differential methylation analyses were conducted using a rank-based regression model and a penalized logistic regression model to identify potential prognostic biomarkers.

Results: The unsupervised analyses of the global methylation profiles did not allow us to differentiate between the distinct oral cancer groups. However, the two supervised analyses confirmed the existence of two oral carcinoma phenotypes. We identified 21 differentially methylated CpGs corresponding to 14 genes. Among them, three CpGs had not been previously assigned to any known gene, and the remaining were associated with genes unrelated to oral cancer. The AGL, WRB, and ARL15 genes were identified as potential prognostic biomarkers.

Conclusions: This study emphasizes the significant role of epigenetic dysregulation in OSCC, particularly in cases preceded by PVL. We have provided data on differential methylation genes that could be involved in the molecular carcinogenesis of PVL-OSCC.