Objective:To investigate the functions and mechanisms of EP3 receptor subtypes in promoting hepatoma Huh-7 cell growth and invasion. Methods:Human hepatocellular carcinoma Huh-7 cells were transiently transfected with EP3-4,EP3-5,EP3-6 and EP3-7 receptor. The expression of EP3 receptor in the transfected cells was detected by RT-PCR and Western blot. The cells were treated with various concentrations of selective EP3 agonist sulprostone. Cell viability was detected in the transfected cells by WST-8. Scratch test was performed to detect invasion ability in the transfected cells. Western blot was employed to detect the phosphorylation level of P-ERK. Results:The expression of EP3 receptor subtypes was markedly increased in the transfected cells by analysis of RT-PCR and Western blot. Under the treatment of 10 μmol/L sulprostone for 24 hours,the cell growth rate of Huh-7 cells transiently transfected with EP3-4,EP3-5 and EP3-7 receptor was increased to 126.7%,124.0%,and 123.8%,respectively. The growth of cell invasion rate separately came to 135.8%,123.5%,and 128.7%. The concentration of intracellular P-ERK in Huh-7 cells over-expressed of EP3-4,EP3-5 and EP3-7 receptor increased by 54.8%,33.4%,and 44.3% individually after 30 minutes exposure of 10 μmol/L sulprostone. However,over-expression of EP3-6 receptor cells had no significant difference in cell growth,cell invasion and the level of intracellular ERK phosphorylation. Conclusion:Our results suggest that EP3 receptor subtypes,including EP3-4,EP3-5 and EP3-7,mediate a great progress of the ability of proliferation and invasion in hepatocellular carcinoma Huh-7 cells,whereas EP3-6 receptor does not. Additionally,the function of EP3 receptor in accelerating cell growth and invasion of Huh-7 cells is in line with the activation of ERK.