BACKGROUND The purpose of the study was to investigate the functional roles of phosphatase in regenerating liver-3 (PRL-3) in hepatocellular carcinoma (HCC), as well as the related molecular mechanisms. MATERIAL AND METHODS HCC tissues and adjacent normal tissues were collected from 124 HCC patients. The mRNA and protein levels of PRL-3 were detected using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot assays, respectively. The relationship between PRL-3 expression and clinical characteristics of HCC patients was evaluated by chi-square test. MTT and Transwell assays were performed to estimate cell proliferation and motility, respectively. RESULTS The expression of PRL-3 was significantly increased in HCC tissues and cells at both protein and mRNA levels (P<0.01 for all). Furthermore, the up-regulation of PRL-3 was positively correlated with hepatic vascular invasion (P=0.019), lymph node metastasis (P=0.012), and TNM stage (P=0.001). The knockdown of PRL-3 suppressed HCC cell proliferation, migration, and invasion, and PR3K/AKT pathway activity was also obviously inhibited in HCC cells with PRL-3 deficiency. The levels of PTEN were negatively associated with PRL-3 expression. PRL-3 might inhibit the protein level of PTEN through enhancing its phosphorylation level. The transfection of si-PTEN can reverse the anti-tumor action caused by PRL-3 knockdown in HCC cells. CONCLUSIONS Up-regulation of PRL-3 may activate the PI3K/AKT signaling pathway and enhance malignant progression of HCC through targeting PTEN.