PDZRN4 acts as a suppressor of cell proliferation in human liver cancer cell lines.

Recently, some reports show that Ligand of Numb Protein-X 1 (LNX1) could be a suppressor gene in gliomas, while our current research has firstly shown that PDZ domain containing ring finger 4 (PDZRN4), another member of LNX family, could also be a potential suppressor in hepatocellular carcinoma (HCC). PDZRN4, also named LNX4 (Ligand of Numb Protein-X 4), is a member of the LNX family. We recently found that PDZRN4, but not LNX1, was down-regulated in HCC samples, and the role of PDZRN4 in the progression of HCC had not been studied before. To address this question, firstly, we evaluated the expression of PDZRN4 in HCC samples and adjacent non-cancerous tissues. Semi-quantitative polymerase chain reaction showed that PDZRN4 was down-regulated in 24/36 (66.7%) HCC samples separately. In addition, our research shows that PDZRN4 is silenced in all of the 12 HCC cell lines tested. Subsequently, cell-based functional assay exhibited that ectopic expression of PDZRN4 inhibits the proliferation, plate colony formation and anchorage-independent colony formation of HCC cells. Collectively, our results showed that PDZRN4 might be a potential tumour suppressor gene and had anti-proliferative effect on HCC cell proliferation, which would be of great significance to the researches on HCC.