Figure 2

Inactivation of miR-31 in NPC. (a) Homozygous deletions of miR-31, adjacent markers (−2mb, −1mb, +1mb, +2mb, +5mb) and loci (LOC402359, CDKN2A/p16, DMRTA1) in EBV-positive NPC tumor lines were detected by PCR. The location of miR-31 and adjacent markers on chromosome 9p21.3 was shown in the right panel. Homozygous deletions of miR-31 were detected in X1915 and X99186. (b) Methylation status of 5’ CpG islands of miR-31 in NPC tumor lines was examined by bisulfite sequencing. The locations of miR-31 and its host gene LOC554202 were indicated. Dense methylation of 5’CpG islands were detected in the C666-1 cell lines and 3 xenografts (C17, X2117 and X666). No methylation were observed in the normal control, NP69. (c) Detection of promoter hypermethylation of NPC cell lines and primary tumors by MSP. M: methylated allele; U: unmethylated alleles. (d) The restoration of miR-31 transcription in 5’-aza-2’deoxycytidine (5-Aza-dC) treated C666-1 was detected by quantitative RT-PCR analysis. By MSP, unmethylated alleles of miR-31 were found in the 5-Aza-dC-treated C666-1 cells.