Ectoine Globally Hypomethylates DNA in Skin Cells and Suppresses Cancer Proliferation

Abstract

Epigenetic modifications, mainly aberrant DNA methylation, have been shown to silence the ex-pression of genes involved in epigenetic diseases, including cancer suppression genes. Almost all conventional cancer therapeutic agents, such as the DNA hypomethylation drug, 5-aza-2-deoxycytidine, have insurmountable side effects. To investigate the role of ectoine in skin cell DNA methylation and cancer cell proliferation, comprehensive methylome sequence analysis, 5-methyl cytosine (5mC) analysis, proliferation and tumorigenicity assays, and DNA methyla-tion-related gene and marker analysis were performed. The results showed that ectoine hypo-methylation in skin cells, especially in the CpG island (CGIs) element and 5mC, was significantly reduced. Moreover, ectoine mildly inhibited skin cell proliferation, but did not induce tumorigenicity in HaCaT cells injected into athymic nude mice. HaCaT cells treated with ectoine for 24 weeks modulated the mRNA expression levels of Dnmt1, Dnmt3a, Dnmt3b, Dnmt3i, Hdac1, Hdac2, Kdm3a, Mettl3, Mettl14, Igf2, Snrpn, and Mest. Overall, ectoine, an excellent DNA protectant, mildly de-methylates DNA in skin cells, modulates the expression of methylation-related genes, and reduces cell proliferation. This evidence suggests that ectoine is a potential anti-aging agent that prevents DNA hypermethylation and subsequently activates cancer-suppressing genes.