A comparative study of bone remodeling molecules expression in different types of jaw ameloblastoma.

Background: Solid ameloblastoma demonstrates a more invasive behavior compared to unicystic. The follicular ameloblastoma is referred that may present a higher recurrence potential compared to the plexiform variant. In this study, the different ameloblastoma clinical types and histopathological variants were examined regarding the expression of bone remodeling-related molecules OPG, RANKL, and TRAIL.

Methods: Immunostained sections of 29 solid and 11 unicystic ameloblastoma cases were semi-quantitatively evaluated and analyzed using Mann-Whitney or Kruskal-Wallis tests.

Results: Solid ameloblastoma showed a significantly increased OPG expression (P = 0.004) associated with the follicular (P < 0.05) than the plexiform or mixed pattern. Lack or low immunoreactivity for RANKL was noted in 79.3% of the solid tumors. A statistically significant result (P < 0.05) was found in the unicystic ameloblastoma for differences by the histopathological pattern (no RANKL expression when plexiform pattern was seen compared to follicular). Comparison between the clinical types showed differences regarding the ratio of OPG/RANKL and TRAIL/RANKL expression. Higher OPG expression over RANKL was observed in 86.2% of the solid compared to 36.4% of the unicystic type. There was no difference in the ratio of TRAIL/RANKL expression in the unicystic, whereas 55.2% of the solid ameloblastomas showed a greater TRAIL expression over RANKL.

Conclusions: Our results suggest OPG overexpression and RANKL underexpression in solid ameloblastoma; this may reflect a possible prevalence of the OPG/TRAIL over the OPG/RANKL signaling pathway, resulting in inactivation of TRAIL-induced apoptosis in ameloblastic cells. In unicystic ameloblastoma, the RANKL/OPG expression immunoprofile among histological variants is compatible with the reported biologic behavior.