Increased Expression of DNA Methyltransferase 1 and 3B Correlates with Tumor Grade in Laryngeal Squamous Cell Carcinoma

Background: DNA methyltransferase (DNMT) enzymes, encoded by DNMT1, DNMT3A and DNMT3B genes, play a major role in the development of cancers through aberrant promoter methylation. Due to little information about the biological and clinical significance of expression changes of these genes in Laryngeal Squamous Cell carcinoma (LSCC), the current study was designed to evaluate the contribution of DNMTs expression as potential diagnostic biomarkers in progression of LSCC. Methods: DNMT1, DNMT3A and DNMT3B expressions in tumoral and normal tissues from thirty-three LSCC patients were evaluated by relative comparative real-time PCR, prior to any therapeutic intervention. Relationship between genes expression and clinicopathological features were also analyzed. Results: The mRNA expression levels of all three DNMTs (DNMT1, DNMT3A and DNMT3B) were significantly elevated in LSCC tumor specimens compared to that of non-tumor tissues (P 0.0001, P=0.011 and P 0.0001, respectively). The expression of DNMT1 and DNMT3B was strongly associated with histopathological tumor grade. Moreover, the mRNA expression levels of DNMT3A were significantly correlated with laryngopharyngeal reflux. No significant relationships existed with other clinicopathological parameters. Conclusion: Data showed that the expression levels of DNMT1, DNMT3A and DNMT3B markedly increased in LSCC tissues. DNMT1 and DNMT3B were mainly overexpressed in high grade LSCC tumors, therefore, they may have a role in LSCC progression. It seems that these genes may serve as diagnostic biomarkers in development of LSCC.