p21-activated kinase 7 is an oncogene in human osteosarcoma

p21-activated kinase 7 (PAK7), also named as PAK5, is a member of Rac/Cdc42-associated Ser/Thr protein kinases. It is overexpressed in some types of cancer such as colorectal and pancreatic cancers. However, the expression status and biological function of PAK7 in osteosarcoma are still ambiguous. To evaluate the expression levels of PAK7 in osteosarcoma tissues and cell lines, immunohistochemistry was used. To investigate the role of PAK7 in cell proliferation, apoptosis and tumorigenicity in vitro and vivo, a recombinant lentivirus expressing PAK7 short hairpin RNA (Lv-shPAK7) was developed and transfected into Saos-2 cells. The silencing effect of PAK7 was confirmed by quantitative real-time PCR (qRT-PCR) and Western blot technique. PAK7 was overexpressed in osteosarcoma tissue and cell line. By knocking-down of PAK7, the proliferation and colony formation of Saos-2 cells were inhibited and apoptosis enhanced significantly. The in vivo tumorigenic ability in xenograft model of Saos-2 cells was also notably inhibited when PAK7 was knocked down. Our results imply that PAK7 promotes cell proliferation and tumorigenesis and may be an attractive candidate for the therapeutic target of osteosarcoma.