PTN and osteosarcoma: MiRNAs are known to play an essential role in the pathogenesis of osteosarcoma either as oncogenic or tumor suppressor agents because, depending on the targets, miRNA can regulate genes that play essential roles in cell proliferation, adhesion, invasion, migration, and metastasis, and apoptosis [28–30]. A few miRNAs has been identified to be play roles in osteosarcoma, such as miR-627-3p targets Pleiotrophin (PTN), which inhibits osteosarcoma cell proliferation and metastasis [31].