show Abstracthide AbstractBackground: Ultra-Conserved-Non-coding Elements (UCNEs) are genomic sequences that exhibit >95% sequence identity between human, mammals, birds, reptiles and fishes. Recent findings reported their functional role in cancer. Aim of this study was to evaluate their DNA methylation modifications in squamous cell carcinoma (SCC) from different mammal species Methods: Fifty SCC from 26 humans, 17 cats, 3 dogs, 1 horse, 1 bovine, 1 badger and 1 porcupine were investigated. Fourteen feline stomatitis and normal samples from 36 healthy human donors, 7 cats, 5 dogs, 5 horses, 2 bovines and 1 badger were collected as normal controls. Bisulfite Next Generation Sequencing evaluated the DNA methylation level from seven UCNEs (uc.160, uc.283, uc.416, uc.339, uc.270, uc.299, uc.328). Results: 57/59 CpGs were significantly different according to the Kruskal-Wallis test (P<0.05) comparing normal vs SCC. A common DNA hypermethylation pattern was observed in SCC from all the species evaluated in this study, with an increasing trend of hypermethylation starting from normal mucosa, through stomatitis to SCC. Conclusions: Our findings indicate that UCNEs are hypermethylated in human SCC, and this behavior is also conserved among different species of mammals. Overall design: Fifty SCC from 26 humans, 17 cats, 3 dogs, 1 horse, 1 bovine, 1 badger and 1 porcupine were investigated. Fourteen feline stomatitis and normal samples from 36 healthy human donors, 7 cats, 5 dogs, 5 horses, 2 bovines and 1 badger were collected as normal controls. Bisulfite Next Generation Sequencing evaluated the DNA methylation level from seven UCNEs (uc.160, uc.283, uc.416, uc.339, uc.270, uc.299, uc.328).