The influence of sun exposure on the DNA methylation status of MMP9, miR-137, KRT14 and KRT19 genes in human skin.

ABSTRACT

BACKGROUND: Studies have shown that a variety of environmental factors and habits are associated with epigenetic changes. In addition, various genes are also found to respond to UV radiation. OBJECTIVES: The aim of this study was to investigate the sun exposure influence on the DNA methylation profile on the matrix metalloprotease-9 (MMP9), microRNA 137 (miR-137), cytokeratin 14 (KRT14) and 19 (KRT19) genes of skin cells of subjects with no history of skin diseases. METHODS: Skin biopsies (5mm) were obtained using a punch technique on sun-exposed (outer forearm) and sun-protected areas (inner arm) from 30 corpses from the Brazilian Service of Death Investigation. Skin types were ranked according to Fitzpatrick's criteria. Genomic DNA was extracted and a DNA methylation analysis was performed using Methylation Specific PCR (MSP) or Methylation-Sensitive Restriction Enzymes (MSRE) of sun-exposed and sun-protected skin areas. RESULTS: No differences were found among the areas (p>0.05; McNemar), with the partially methylated condition found to be a common event in skin for both MMP9 and miR-137 genes and the methylated condition for both KRT14 and KRT19 genes. Additional analysis showed no differences in the methylation status when age, gender and skin type were considered, however, the methylation status of miR-137 gene seems to be gender-related. CONCLUSIONS: We conclude that sun exposure does not induce changes in the DNA methylation status in MMP9, miR-137, KRT14 and KRT19 genes.