Research Article Identification of a Novel Methylated Gene in Nasopharyngeal Carcinoma: TTC40 Wajdi Ayadi, 1 Nesrine Allaya, 1 Hanèn Frikha, 1 Emna Trigui, 1 Abdelmajid Khabir, 2 Abdelmonem Ghorbel, 2 Jamel Daoud, 2 Mounir Frikha, 2 Ali Gargouri, 1 and Raja Mokdad-Gargouri 1 1 Laboratory of Biomass Valorization and Protein Production in Eukaryotes, Center of Biotechnology of Sfax, University of Sfax, 3038 Sfax, Tunisia 2 University Hospital Habib Bourguiba of Sfax, 3029 Sfax, Tunisia Correspondence should be addressed to Wajdi Ayadi; zaidounemail@yahoo.fr Received 27 February 2014; Accepted 10 June 2014; Published 30 June 2014 Academic Editor: Claus-Peter Richter Copyright © 2014 Wajdi Ayadi et al. Tis 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 diferentially methylated in NPCs versus nontumors. Te frst, defned as hypermethylated, corresponds to a CpG island at the 5  -end of the tetratricopeptide repeat domain 40 (TTC40) gene, whereas the second, defned as hypo-methylated, is located on repetitive sequences at chromosomes 16p11.1 and 13.1. Tereafer, the epigenetic alteration on the 5  -TTC40 gene was confrmed by methylation-specifc PCR, showing a signifcant aberrant methylation in NPCs, compared to nontumors. In addition, the bisulfte sequencing analysis has shown a very high density of methylated cytosines in C15, C17, and X666 NPC xenografs. 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 signifcantly lower in tumors than in nontumors, which is associated with 5  -TTC40 gene hypermethylation. In conclusion, we found that the 5  -TTC40 gene is frequently methylated and is associated with the loss of mRNA expression in NPCs. Hypermethylation of 5  -TTC40 gene might play a role in NPC development; nevertheless, other studies are needed. 1. Introduction Nasopharyngeal carcinoma (NPC) is a malignancy with a remarkable racial and geographic distribution [1, 2]. In Tunisia, it represents the most frequent head and neck cancer, with an annual incidence of about 4 cases per 100,000 per- sons. Tere are several clinical and biological characteristics which are specifc to North African patients, especially the two peaks of frequency according to age, the frst around 50 and the second below 25 (20–25% of cases) [3]. Te etiology of NPC is multifactorial and includes genetic susceptibility, exposure to various carcinogens, and Epstein- Barr virus (EBV) latent infection [4, 5]. Epigenetic changes also play a crucial role in nasopharyngeal carcinogenesis. Such epigenetic alterations of malignant tumors, compared with their analogous normal tissues, include both decreases in global DNA methylation (hypomethylation) commonly assessed in DNA repeat regions and concomitant increases (hypermethylation) in specifc regions with the ability to afect gene expression [6]. Promoter hypermethylation has been proposed as a common mechanism for the transcrip- tional inactivation of several tumor suppressor genes (TSGs) in human carcinomas. For NPC, silencing by promoter methylation has been reported for variety of TSGs, including Ras association domain family 1A (RASSF1), retinoic acid receptor 2 (RAR 2), death-associated protein kinase (DAP- kinase), and deleted in lung and esophageal cancer 1 (DLEC1) [7–9]. It has been demonstrated that the gene alterations are involved in NPC pathogenesis by disrupting the normal regulation of apoptosis and cell cycle control [10–13]. Hindawi Publishing Corporation BioMed Research International Volume 2014, Article ID 691742, 7 pages http://dx.doi.org/10.1155/2014/691742