Mutual regulation between microRNA-373 and methyl-CpG-binding domain protein 2 in hilar cholangiocarcinoma

Figure 2 Methylation of miR-373 promoter-associated CpG island in hilar cholangiocarcinoma. A: Top panel, a schematic drawing of the putative CpG island in the 5′-flank region of miR-373 gene; Bottom panel, sequence information of miR-373 gene including partial 5′-flank region. The transcriptional start site (TSS) in boldface uppercase indicated by black arrow, 26 CpG dinucleotides are underlined and italic, pre-miR-373 sequences are capitalized; B: DNA methylation detected by methylation-specific polymerase chain reaction (MSP). Five representative cases were shown to indicate homozygous methylation (cases 1, 3), heterozygous methylation (cases 4, 5) and unmethylated (case 2), respectively. Lanes labeled M and U denote products amplified by primers recognizing methylated and unmethylated sequences; C: Percent of methylated reference (PMR) of miR-373 promoter-associated CpG island in tumor group is significant higher than control (^bP < 0.01 vs control); D: Relationship between CpG island methylation and miR-373 expression in hilar cholangiocarcinoma. A reverse correlation between PMR values and miR-373 expression could be observed (high ΔC_T value indicated low expression) excluding 3 extra samples displayed high PMR values and high mRNA expression(samples 14, 18 and 44).