Immunohistochemical detection of platelet-derived endothelial cell growth factor/thymidine phosphorylase and angiopoietins in ameloblastic tumors.

Background: To evaluate the roles of angiogenic factors in the development and progression of odontogenic tumors, expression of platelet-derived endothelial cell growth factor/thymidine phosphorylase (PD-ECGF/TP) and of angiopoietins in ameloblastic tumors as well as in tooth germs.
Methods: Tissue specimens of 11 tooth germs, 44 ameloblastomas, and five malignant ameloblastic tumors were examined immunohistochemically with the use of antibodies against PD-ECGF/TP and angiopoietin-1 and -2.
Results: Immunohistochemical reactivity for PD-ECGF/TP was detected in mesenchymal cells in tooth germs and stromal cells in ameloblastic tumors, and the level of immunoreactivity for PD-ECGF/TP was significantly higher in ameloblastomas than in tooth germs. Granular cell ameloblastomas showed PD-ECGF/TP reactivity in granular neoplastic cells as well as in stromal cells. Immunoreactivity for angiopoietin-1 and -2 was detected predominantly in odontogenic epithelial cells near the basement membrane in tooth germs and in benign and malignant ameloblastic tumors. Malignant ameloblastic tumors had decreased angiopoietin-1 reactivity and ameloblastic carcinomas had increased angiopoietin-2 reactivity as compared with the respective levels in tooth germs and ameloblastomas. Immunohistochemical reactivity for angiopoietin-2 was slightly higher in follicular ameloblastomas than in plexiform ameloblastomas.
Conclusion: Expression of PD-ECGF/TP and angiopoietin-1 and -2 in tooth germs and ameloblastic tumors suggests that these angiogenic factors participate in tooth development and odontogenic tumor progression by regulating angiogenesis. Altered expression of PD-ECGF/TP and angiopoietins in ameloblastic tumors may be involved in oncogenesis, malignant potential, and tumor cell differentiation.