Aberrant DNA Methylation of G-protein-coupled Bile Acid Receptor Gpbar1 (TGR5) is a Potential Biomarker for Hepatitis B Virus Associated Hepatocellular Carcinoma

Abstract

Background: G-protein-coupled bile acid receptor Gpbar1 (TGR5) is a newly identified liver tumor suppressor in carcinogenesis. This present study was therefore to determine the potential value of serum TGR5 promoter methylation in identifying hepatocellular carcinoma (HCC) from chronic hepatitis B (CHB) patients.Methods: The circulating cell-free DNA (cfDNA) was extracted from a retrospective dataset including 160 HCC, 88 CHB and 45 healthy controls (HCs). Methylation status of TGR5 promoter was examined by methylation-specific polymerase chain reaction (MSP).Results: Hypermethylation of the TGR5 promoter occurred significantly more frequent in HCC (77/160, 48.13%) than CHB (12/88, 13.64%; p<0.01) and HCs (2/45, 4.44%; p<0.01). The methylation rate of TGR5 in HCC patients ≥60 years old was significantly higher than those <60 years old (p<0.05). Alpha fetoprotein (AFP) had sensitivity of 58.13%, 30.63% and 24.38% at cut-off points of 20, 200 and 400ng/ml respectively; while TGR5 methylation combined AFP had sensitivity of 81.25%, 68.13% and 65%. AFP had specificity of 47.73%, 92.05% and 98.86% at cut-off points of 20, 200 and 400ng/ml respectively; while TGR5 methylation combined AFP had specificity of 38.64%, 78.41% and 85.23%. AFP had Youden index of 0.06, 0.23 and 0.23 at cut-off points of 20, 200 and 400ng/ml respectively; while TGR5 methylation combined AFP had Youden index of 0.20, 0.47 and 0.50.Conclusions: Our findings strongly suggested the combination of serum TGR5 promoter methylation and AFP enhanced the diagnostic value of AFP alone in discriminating HCC from CHB patients.

Circulating Tumor DNA and Hepatocellular Carcinoma

“…78 The methylated SEPT9 test showed high diagnostic accuracy for HCC diagnosis, with an AUROC of 0.94; however, the sensitivity was 64% for BCLC stage A disease. Other single-candidate studies of ctDNA showed promise for hypermethylation of VIM, FBLN1, TFPI2, TGR5, MT1M, and MT1G [79][80][81][82] or hypomethylation of LINE-1 elements 83 in early detection of HCC in case-control studies.…”

TGR5, Not Only a Metabolic Regulator

“…Our group found that TGR5 activation could suppress gastric cancer cell proliferation and migration via inhibiting STAT3 pathway (Guo et al, 2015b). Han et al (2014) demonstrated that the aberrant hypermethylation of TGR5 promoter in serum cfDNA might serve as a biomarker for the surveillance of HCC. Hong et al (2010) found that TGR5 receptor is over-expressed in oesophageal adenocarcinoma tissues and indicated TGR5 may play an important role in oesophageal adenocarcinoma.…”

Impact of circulating tumor DNA in hepatocellular and pancreatic carcinomas

“…Xu et al constructed a diagnostic prediction model using a cfDNA methylation marker panel that predicted HCC survival and could effectively discriminate patients with HCC from individuals with HBV/ HCV infection, fatty liver disease as well as healthy controls superior to AFP (Xu et al 2017). Although a multitude of aberrant methylated genes could be identified as prognostic target in HCC, there is no recognized biomarker confirmed in multiple centers (Han et al 2014;Iizuka et al 2011;Ji et al 2014;Oussalah et al 2018;Sun et al 2013;Wang et al 2006;Wen et al 2015;Wu et al 2017;Zhang et al 2013).…”