Fig. 1

Hypermethylation modified C2orf40 is downregulated in nasopharyngeal carcinoma (NPC) cells and it is associated with a poor prognosis. A The expression profile analysis of three GEO datasets (GSE12452, GSE53819, and GSE64634) showed that the C2orf40 expression level in NPC tissues was significantly lower than that in normal nasopharyngeal epithelial tissues. B The C2orf40 expression in NPC tissues (n = 8) and normal nasopharyngeal epithelial tissues (n = 16) was measured by qRT-PCR. C Downregulation of C2orf40 expression was confirmed by Western blotting in four matched NPC and adjacent normal tissues. D‒E The expression level of C2orf40 was analyzed in one immortalized nasopharyngeal epithelial cell line (TERT) and seven NPC cell lines (CNE-1, CNE-2, HONE-1, SUNE-1, HNE-1, HK-1, and 5-8F) by qRT-PCR (D) and Western blotting (E). F The quantitative methylation levels in 24 paired NPC and normal nasopharyngeal epithelial tissues were detected using pyrosequencing. G The NPC cell lines were treated with methyltransferase inhibitor DAC for 48 h, and then, C2orf40 mRNA expression was determined by qRT-PCR. H After collecting clinicopathological and follow-up data and conducting immunohistochemistry, the correlations between C2orf40 expression levels and survival prognosis were analyzed in 94 NPC patients. The experiments were performed in triplicate and repeated twice. Data are presented as the mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001