Knockdown of WWP1 inhibits growth and invasion, but induces apoptosis of osteosarcoma cells.

Recent studies have shown that WW domain containing E3 ubiquitin protein ligase 1 (WWP1) is frequently amplified in various cancers. However, the role of WWP1 in osteosarcoma has not yet been studied. Here, we analyzed the mRNA levels of WWP1 in 25 pairs of osteosarcoma and adjacent non-tumorous samples. We found that WWP1 were higher in 88% osteosarcoma tissues as compared with their matched normal bone tissues. Knockdown of WWP1 using small interfering RNA further showed that deficiency of WWP1 blocked cell growth and cell invasion, and caused G1-phase arrest and cell apoptosis in osteosarcoma cells (MG63 and HOS). Furthermore, knocking down WWP1 affected the protein levels of apoptosis (Bcl2 and Bax) and invasion related factor (MMP2, MMP9, β-catenin and E-cadherin). These results suggest that WWP1 might be an oncogene and shed lights on targeted therapy of osteosarcoma.