Research Article Identification of a Novel Methylated Gene in

Copyright © 2014 Wajdi Ayadi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. To further explore the epigenetic changes in nasopharyngeal carcinoma (NPC), methylation-sensitive arbitrarily primed PCR was performed on NPC biopsies and nontumor nasopharyngeal samples. We have shown mainly two DNA fragments that appeared to be differentially methylated in NPCs versus nontumors. The first, defined as hypermethylated, corresponds to a CpG island at the 5-end of the tetratricopeptide repeat domain 40 (TTC40) gene, whereas the second, defined as hypo-methylated, is located on repetitive sequences at chromosomes 16p11.1 and 13.1. Thereafter, the epigenetic alteration on the 5-TTC40 gene was confirmed by methylation-specific PCR, showing a significant aberrant methylation in NPCs, compared to nontumors. In addition, the bisulfite sequencing analysis has shown a very high density ofmethylated cytosines in C15, C17, andX666NPC xenografts. To assess whether TTC40 gene is silenced by aberrant methylation, we examined the gene expression by reverse transcription-PCR. Our analysis showed that the mRNA expression was significantly lower in tumors than in nontumors, which is associated with 5-TTC40 gene hypermethylation. In conclusion, we found that the 5-TTC40 gene is frequentlymethylated and is associatedwith the loss ofmRNA expression in NPCs. Hypermethylation of 5-TTC40 gene might play a role in NPC development; nevertheless, other studies are needed. 1