Umeda S et al. - In the current study it was shown that down-regulation of GPR155 may serve as a prognosticator of hepatocellular carcinoma after curative resection, and also predicts initial recurrence sites independent of hepatitis virus infection.

Methods
GPR155 expression, DNA methylation, and copy number was determined in HCC cell lines.
The clinical significance of GPR155 expression was evaluated using 144 pairs of surgically-resected liver and normal tissues, with subgroup analysis based on hepatitis virus infection.

Results
GPR155 mRNA expression levels were decreased in 89% of HCC cell lines. No DNA methylation was detected, whereas copy number alterations were present in 5 HCC cell lines.
GPR155 mRNA expression level was independent of background liver status and significantly lower in HCC tissues than corresponding normal liver tissues.
GPR155 protein expression was associated with GPR155 mRNA expression. Down-regulation of GPR155 was associated with more aggressive HCC phenotypes, including high pre-operative alpha-fetoprotein, poor differentiation, serosal infiltration, vascular invasion, and advanced disease stage.
Down-regulation of GPR155 was associated with worse prognosis after curative resection independent of hepatitis virus infection.
Patients with extrahepatic recurrences had lower GPR155 expression than intrahepatic recurrences.