DNA methylation alterations in the epithelium-mesenchymal transition in the pterygium

Abstract

Pterygium is a very common ocular surface alteration in our country, with variable prevalence, affecting mainly individuals who live in areas close to the equator and who work exposed to the sun. The etiology of pterygium is multifactorial, involving oxidative stress, inflammatory mediators, extracellular matrix modulators, apoptotic and oncogenic mediators, lymphangiogenesis factors and the epithelial-mesenchymal transition. Recent studies indicate that genes encoding proteins involved in the epithelial-mesenchymal transition process, such as E-cadherin, show abnormal expression in the pterygium due to epigenetic alterations. Epigenetics is defined as the study of hereditary changes in gene expression that do not depend on changes in the sequence of nitrogenous bases in DNA. The most studied epigenetic modifications are DNA methylation, histone modifications, chromatin remodeling factors and non-coding RNAs. It is now recognized that hypermethylation of CpG dinucleotides located in the promoter region of specific genes is inversely correlated with their expression levels.