Expression and clinical significance of PcG-associated protein RYBP in hepatocellular carcinoma.

Ring1 and YY1 binding protein (RYBP), a member of the polycomb group proteins, has been implicated in transcription repression and tumor cell-specific apoptosis. Previously, RYBP has been reported as a putative tumor suppressor in cancer tissues by regulating mouse double minute 2 homolog-p53 signaling. However, the exact role and underlying mechanisms of RYBP in cancer remain to be fully elucidated. The present study investigated the expression profile of RYBP in hepatocellular carcinoma (HCC) and examined the association between the expression of RYBP and metastasis of HCC. It was found that RYBP was downregulated in HCC tissues, compared with matched adjacent non-tumor tissues, as detected by reverse transcription-quantitative polymerase chain reaction and immunohistochemistry. In addition, Kaplan-Meier survival analysis showed that the negative expression of RYBP was associated with decreased overall survival rates in patients with HCC. It was also found that RYBP was associated with zinc finger E-box binding homeobox 1 and zinc finger E-box binding homeobox 2, which were overexpressed in HCC and correlated with epithelial-mesenchymal transition. The results of the present study suggested the importance of RYBP in HCC and its possible mechanism in the metastasis of HCC.