The association between DNA methylation status and Epstein-Barr virus infection in laryngeal carcinomas.

Introduction: Infection with Epstein-Barr virus is a known risk factor for laryngeal carcinogenesis; it might influence DNA methylation acting as an epigenetic driver in this type of malignancy.

Methods: Paired laryngeal tissues (neoplastic and peri-neoplastic) harvested from 24 patients were included in the study. Eleven patients expressing latent/lytic EBV genes were considered positive. 5-mC% was determined using ELISA technique and TSGs (PDLIM4, WIF1, DAPK1) promoters' methylation percentages were quantified by qMS-PCR. DNMTs (DNMT1 and DNMT3B) expression levels were quantified in qRT-PCR.

Results: Overall, in laryngeal neoplastic samples vs peri-neoplastic ones, lower 5mC% (p=0.004) and higher TSGs promoters hypermethylation were found (p<0.0001). Significant correlation between PDLIM4 and DAPK1 promoter methylation and 5-mC% (PDLIM4 p=0.0186; DAPK1 p=0.0259) was noted. Higher 5-mC% (p=0.0041), lower PDLIM4 gene promoter methylation (p=0.0017) and overexpression of DNMTs (DNMT1: p=0.0018, respectively DNMT3B: p=0.0017) were associated with EBV infection. Also, significant differences between EBV-positive and EBV-negative cases based on tumor stage (T) were noted for 5mC% in both T1/T2 (p=0.0364) and T3/T4 stages (p=0.0275), and for PDLIM4 promoter methylation in T1/T2 stages (p=0.0121).

Conclusion: Future studies are needed to more effectively illustrate the interplay between EBV infection and these epigenetic mechanisms. Notably, our study highlighted a correlation between EBV and epigenetic changes in laryngeal carcinoma.