Animal models of oral cancer metastasis

Metastasis is a complex, highly coordinated series of events in which cells from a primary tumor invade lymphatic and/or blood vessels and spread to regional lymph nodes and/or distant organs, establishing proliferating tumor deposits. Because this process requires the interaction of tumor cells with many types of normal cells, tissues, and systems of an intact organism, in vitro model systems provide very limited information regarding the biology of metastasis. Therefore, in vivo model systems are needed to further our understanding of the metastatic process. Several major types of murine model systems have been most informative and include those in which tumor cells are implanted into tissues or injected into the blood system. Also useful are autochthonous models, in which tumors with metastatic potential are induced at the primary site, in this case, the oral cavity, through treatment of the oral mucosa with chemical carcinogens or by genetically engineering changes in the expression of oncogenes and tumor suppressor genes in the oral epithelia. This chapter summarizes the progress that has been made in the development of mouse models of metastasis in oral cancer and the contributions of these models to our understanding of the biology of oral cancer metastasis.