Downregulation of uncoupling protein 1 by hypermethylation in gastric cancer activates Rap1 signaling

Figure 2 Uncoupling protein 1 expression is silenced by promoter hypermethylation in gastric cancer. A: The parts of nucleotide sequences of a CpG island in the Uncoupling protein 1 (UCP1) promoter region including seven CG sites. The upper line shows nucleotide sequences in the GenBank, and the lower line shows those after treatment with sodium bisulfite; B: Bisulfite sequencing PCR analysis of UCP1 methylation status in gastric cancer (GC) cell lines. Methylated DNA was detected in all three GC cell lines (methylated C is indicated with a blue arrow). The methylation status of UCP1 in GC tissues was consistent with the UCP1 expression level; C: Unmethylated CG sites (orange arrow) were detected in GC tissue with positive UCP1 expression; D: Both unmethylated and methylated CG sites (green arrow) were detected in GC tissues with moderate expression of UCP1; E: Methylated CG sites (blue arrow) were detected in GC tissues with negative expression of UCP1; F: The expression of UCP1 in all GC cell lines was restored after 5-Aza treatment. UCP1 mRNA expression levels (right) with or without 5-Aza treatment in SGC-7901, AGS, and BGC-823 cells were detected using reverse-transcription PCR, compared with the house-keeping gene GAPDH as internal control (left). UCP1: Uncoupling protein 1.