Abstract
Osteosarcoma is an aggressive type of bone tumor that commonly occurs in pediatric age groups. The complete molecular mechanisms behind osteosarcoma formation and progression require elucidation. B7-H3 is a protein of the B7 family that acts as a co-stimulatory molecule with a significant role in adaptive immune responses. The link between B7-H3 expression and its role in different types of cancer remains unclear. B7-H3 protein exhibits different functional roles in in vivo and in vitro conditions that remain controversial. In the present study, a murine model of osteosarcoma was successfully established using a modified protocol so as to easily obtain a low grade and metastatic form of osteosarcoma tissue without complication. Histological data showed that a less organized and highly proliferative mass of cells was observed in the osteosarcoma tissue. A higher expression level of B7-H3 protein was also observed at each advanced stage of osteosarcoma, which indicated the contributory role of the protein in the development of the primary and metastatic forms of osteosarcoma. Immunohistochemistry was performed, which showed that the overexpression of B7-H3 protein in the metastatic form of osteosarcoma may be associated with its migration and invasion.