Silencing of carboxypeptidase E inhibits cell proliferation, tumorigenicity, and metastasis of osteosarcoma cells

Carboxypeptidase E (CPE), a prohormone processing enzyme, has been implicated in the progression of multiple malignancies. However, the biological role and molecular mechanisms of CPE in osteosarcoma remain elusive. In this study, we assessed the effects of CPE on cell proliferation, tumorigenicity, migration, and invasion in osteosarcoma. Our results showed that silencing of CPE significantly inhibited cell proliferation, caused cell cycle arrest at G(0)/G(1) phase, decreased the expression levels of cell cycle protein, cyclin D(1), and inhibited tumorigenicity in vivo. Additionally, CPE downregulation repressed the migratory and invasive capacities of osteosarcoma cells in vitro. Furthermore, overexpression of CPE-ΔN (a splice variant of CPE) enhanced the cell growth, migration, and invasion of osteosarcoma cells. It is possible that both CPE forms are involved in the tumorigenesis and development of osteosarcoma, and therefore CPE may provide a promising biological target for osteosarcoma therapy.