RESUMO
OBJECTIVE: Proliferative verrucous leukoplakia (PVL) is considered a clinically distinct entity from other oral leucoplakias (OLs) due to its clinical presentation and evolution. However, molecular differences between them remain unclear. We aimed to determine whether there are methylation differences between PVL and other forms of OLs. MATERIALS AND METHODS: Oral biopsies from 12 patients with PVL, eight patients with homogeneous leucoplakia (HL), and 10 healthy individuals were obtained for a genome-wide DNA methylation analysis via the Infinium EPIC Platform. RESULTS: A total of 1815 differentially methylated CpGs were found between PVL and HL, with a prominent state of hypermethylation in HL patients. CpGs covered 813 genes with distinct roles, including cell adhesion, extracellular matrix organization, and cell and synaptic signaling. 43% of these genes had been previously described in cancer and associated with prognosis. We developed a multinomial logistic regression model able to differentiate HL, PVL, and control samples. The model had a cross-validated estimate of 73% and included differentially methylated cancer-related genes between the pathological conditions and the healthy donors, including ADNP, BRCA2, CDK13, GNB1, NIN, NUMB, PIK3C2B, PTK2, SHISA4, THSD7B, WWP1, and ZNF292. It also included CpGs covering differentially methylated genes in HL (MEN1 and TNRC6B) and PVL (ACOXL, ADH1B, CAMTA1, CBFA2T3, CPXM2, LRFN2, SORCS2, and SPN). CONCLUSIONS: PVL and HL present differential methylation patterns that could be linked to their differential clinical behavior. Our findings show the potential of methylation markers and suggest novel diagnostic biomarkers.
RESUMO
OBJECTIVE: Proliferative verrucous leukoplakia (PVL) has high rates of malignant transformation into oral squamous cell carcinoma (OSCC), but the clinical and evolutionary pattern of OSCC from PVL (PVL-OSCC) is more favorable than that of OSCC not preceded by PVL (OSCC). Here, we aimed to explore the pathophysiologic differences between PVL-OSCC and OSCC through transcriptomic and DNA methylation analyses. MATERIALS AND METHODS: In this case-control study, oral biopsies from 8 PVL-OSCC and 10 OSCC patients were obtained for global sequencing using RNAseq and a genome-wide DNA methylation analysis via the Infinium EPIC Platform (graphical abstract). RESULTS: One hundred and thirty-three differentially expressed genes (DEGs) were detected, 94 of them upregulated in OSCC. Most of these genes were previously described in cancer and associated with prognosis. The integrative analysis revealed 26 DEGs, corresponding to 37 CpGs, whose promoters were regulated by DNA methylation. Twenty-nine of the CpGs were found as hypermethylated in PVL-OSCC. Only 5 of the genes that were aberrantly methylated and differentially expressed were upregulated in PVL-OSCC patients, whereas 21 were underexpressed. CONCLUSIONS: PVL-OSCC patients presented lower expression of cancer-related genes. Hypermethylation of the promoter region of many genes was also noticed, indicating that DNA methylation could be a regulatory mechanism.
