Fig. 6

The expression of PPP1R14A and SCNN1B, two individual genes of the identified prognostic signature, are regulated by promoter region methylation. a Expression levels of PPP1R14A and SCNN1B without (−) or with (+) 5-aza treatment were analyzed by qPCR in eight gastric cell lines (GES1, NUGC3, SNU5, SNU16, NCI-N87, AGS, MGC803, and BGC823). b Schematic diagrams of CpG islands in the promoter region of PPP1R14A and SCNN1B. MF methylation forward primer, MR methylation reverse primer, UF unmethylation forward primer, UR unmethylation reverse primer, BSSQ-F bisulfite sequencing forward primer, BSSQ-R bisulfite sequencing reverse primer. c Methylation status of PPP1R14A and SCNN1B was detected by methylation specific PCR (MSP) in gastric cell lines. IVD in vitro methylated DNA, NL normal lymphocyte DNA, M methylated alleles, U unmethylated alleles. d Bisulfide sequencing (BSSQ) of PPP1R14A was performed in GES1 and AGS cell lines. For SCNN1B, GES1 and SNU16 cell lines were analyzed. Red solid dots represent methylated CpG sites, and green solid dots denote unmethylated CpG sites. The horizontal black bar demarcates the primers of MSP, which are included in the region of BSSQ