GS-HepG2

Promoter Methylation and H3K27 Deacetylation Co-Regulate VIPR1 Transcription in Hepatocellular Carcinoma

Vasoactive intestinal peptide receptor 1 (VIPR1) is differentially expressed in human cancers. To uncover its clinical relevance and mechanism of transcriptional regulation in hepatocellular carcinoma (HCC), Lu et al. first identified VIPR1 CpG island by UCSC Genome Browser.

After selection, methylation status of seven CpG sites was examined by pyrosequencing (Fig. 1B). DNA methylation was detected at seven CpG sites in all of six HCC cell lines (SK-Hep-1, Huh7, Hep3B, MHCC97-L, MHCC97-H, Gs-HepG2) (Fig. 1C). Among these six cell lines, methylation levels of SK-Hep-1, Huh7, MHCC97-L and MHCC97-H cells were higher than those of Hep3B and Gs-HepG2 cells (Fig. 1D). Methylation levels of VIPR1 in 41 pairs of HCC and paracancerous tissues from MethHC database were significantly higher in HCC tissues than those in corresponding non-cancerous tissues (Fig. 1E), while mRNA levels were significantly lower in HCC than those in non-cancerous tissues (Fig. 1F). Further correlation analysis was performed between methylation and mRNA expression levels in 41 paired adjacent normal tissues and HCC tissues, as well as 189 HCC tissues from MethHC database. A negative correlation between methylation and mRNA levels of VIPR1 was observed in these tissues (Fig. 1G). Another 10 pairs of matched HCC tissues and paracancerous tissues were recruited to validate the methylation status of VIPR1. As shown in Figure 1H, high methylation levels were detected at each CpG locus in HCC tissues, while low methylation levels were observed in non-cancerous tissues. The mean levels of methylation at seven CpG sites in HCC tissues were higher than those in corresponding non-cancerous tissues (Fig. 1I), which was consistent with bioinformatics analyses.