p16 Expression in Odontogenic Cysts

Abstract

Background: p16 protein acts as a tumor suppressor and its functional loss seems to be one of the most frequent genetic alterations in human tumors. Because there is a lack of information, the expression of p16 is examined in different odontogenic cysts to clarify the possible role of this factor to determine the biological and clinical behavior of these lesions.

Methods: Eighteen radicular cysts (RC), 9 follicular cysts (FC), and 15 keratocystic odontogenic tumors (KCOT) were immunohistochemically evaluated. Chi-square test was used to compare data.

Results: The cysts showed a different pattern of p16 expression according to the histologic type. All RCs or FCs were strongly or moderately positive for p16, whereas all KCOT cases exhibited loss of p16 expression or a low immunoreactivity.

Conclusions: KCOT is characterized by an aggressive potential of growth and recurrences after removal. Here, a dysregulation of the p16 pathway in KCOT was demonstrated. This lack of expression of positivity for p16 in KCOT could help explain the differences in the clinical and pathological behavior of KCOT and could be related to the increased aggressive behavior, invasiveness and high frequency of recurrences found in KCOT.

Keywords: Cell cycle proteins, immunohistochemistry, odontogenic tumors, p16 genes