Fig. 2

Identification of the hypermethylated and downregulated gene CLDN11 in NPC. a Bisulfite sequencing analysis was performed on − 137 to + 405 in C666.1 and NP69 cells, and seven paired NPC clinical samples. Each horizontal row represents a single clone; the methylation percentages of at least eight individual clones are indicated as unmethylated (○) and methylated (●) CpG sites. The lower panel shows the average methylation percentage for each sample. qRT-PCR analysis of CLDN11 mRNA expression was performed in (b) 6 paired NPC tissues and (c) NP69 cells and four NPC cell lines. The results were normalized to β-Actin expression. d Columns represent the relative fold-change of the restored CLDN11 mRNA expression normalized with respect to β-Actin expression in NPC cell lines with (+) or without (−) 10 μM 5’Aza treatment. e Immunohistochemistry staining analysis of CLDN11 protein expression in nine paired NPC tissue arrays (Pantomics). Tumor tissues (T) and the corresponding adjacent normal tissues (N) are indicated. The results are shown at 200× magnification (CLDN11 staining intensity T < N: 7 pairs, T = N: 2 pairs). Higher magnification is shown in Additional file 4: Figure S2. White dotted lines mark the border of basement membrane of normal epithelial cells; black triangles indicate the apical membranous staining signals of CLDN11