Jaw osteosarcoma models in mice: first description.

Background: Osteosarcoma (OS) is the most common cancer of bone. Jaw osteosarcoma (JOS) is rare and it differs from other OS in terms of the time of occurrence (two decades later) and better survival. The aim of our work was to develop and characterize specific mouse models of JOS.
Methods: Syngenic and xenogenic models of JOS were developed in mice using mouse (MOS-J) and human (HOS1544) osteosarcoma cell lines, respectively. An orthotopic patient-derived xenograft model (PDX) was also developed from a mandibular biopsy. These models were characterized at the histological and micro-CT imaging levels, as well as in terms of tumor growth and metastatic spread.
Results: Homogeneous tumor growth was observed in both the HOS1544 and the MOS-J JOS models by injection of 0.25 × 10 ⁶ and 0.50 × 10 ⁶ tumor cells, respectively, at perimandibular sites. Histological characterization of the tumors revealed features consistent with high grade conventional osteosarcoma, and the micro-CT analysis revealed both osteogenic and osteolytic lesions. Early metastasis was encountered at day 14 in the xenogenic model, while there were no metastatic lesions in the syngenic model and in the PDX models.
Conclusion: We describe the first animal model of JOS and its potential use for therapeutic applications. This model needs to be compared with the usual long-bone osteosarcoma models to investigate potential differences in the bone microenvironment.