Juxta-epithelial hyalinization inhibits tumor growth and invasion in ameloblastoma

In histological examination of ameloblastoma, marked juxta-epithelial hyalinization of the connective tissue adjacent to the epithelium was observed in many cases. However, the physicochemical mechanism of these changes and its role in ameloblastoma is still not understood. To analyze the expression pattern of the different types of basement membrane related molecules, apoptosis-related factors and their possible role in juxta-epithelial hyalinization, six cases of ameloblastoma were examined. Immunohistochemical staining was done using cell surface type heparan sulfate (HS), 10E4, basement membrane type HS, JM403, Heparanase, Caspase-6, BCL-2 and CD34 antibodies. Hyalinized area in all sections, were strongly positive to 10E4, but negative to heparanase. There was no CD34 positive endothelial cells within the hyalinization area. Tumor cells adjacent to this area were positive to 10E4, heparanase and caspase-6. This result suggests that hyalinization have an effect on tumor growth and stop stromal-tumor cell interaction by the help of HSPGs, resulting in the inhibition of the function of heparanase and angiogenesis. Finally, tumor cells adjacent to the hyalinization undergoes program cell death.