Comparison of Proliferating Cell Nuclear Antigen Expression in Odontogenic Keratocyst and Ameloblastoma: An Immunohistochemical Study

Abstract

Proliferating cell nuclear antigen (PCNA) is a nuclear protein synthesized in the late G1 and S phase of the cell cycle, and immunohistochemical detection of the protein represents a useful marker for the proliferating fraction of cells in tissue specimens. PCNA expression was studied in odontogenic keratocysts (n = 15) and ameloblastomas (n = 46) using an avidin–biotin–peroxidase complex method on routinely processed paraffin sections. The percentage of PCNA-positive cells determined by point counting was significantly lower in the ameloblastomas (mean 9.4%, standard deviation (SD) 11.0) than in odontogenic keratocysts (mean 29.9%, SD 24.0). In ameloblastomas, the mean percentage of PCNA-positive cells was lowest in the acanthomatous pattern and highest in plexiform pattern. The mean percentage of PCNA-positive cells in plexiform pattern was non-significantly higher than that in follicular pattern. The mean percentage of PCNA-positive cells in plexiform and follicular patterns was significantly higher than that in cyctic and acanthomatous patterns. The frequency of PCNA-positive cells was significantly higher in the peripheral cells of follicular and plexiform patterns than in the central cells of both patterns (p < 0.01). Therefore, peripheral cells were regarded as reserve cell of central cells. The mean percentage of PCNA-positive cells in the epithelial lining of odontogenic keratocyst was not significantly different from those in the peripheral cells of follicular and plexiform patterns of ameloblastoma. In contrast, the odontogenic keratocyst exhibited a mean percentage of PCNA-positive cells which was statistically higher than that in other histological elements of ameloblastomas. The present study suggests that odontogenic keratocyst is regarded as benign odontogenic tumour.

Cell proliferation and apoptosis in ameloblastomas and keratocystic odontogenic tumors

“…This is in accordance with previous reports (10,11). In contrast, studies have also demonstrated a higher cell proliferation in AM in relation to KOT (7)(8).…”

“…Since KOT had been classified as an odontogenic cyst, several authors have compared cell proliferation between KOT and odontogenic cysts (8,12,13). Although several authors have assessed cell proliferation and apoptosis in the odontogenic epithelium in AM and in the epithelial lining in KOT (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22), few studies have compared cell proliferation between these tumors (7,8,11) and no previous study has simultaneously evaluated cell proliferation and apoptotic indexes in AM and KOT, comparing both lesions. Therefore, this is the first study assessing comparatively cell proliferation and apoptosis indexes in AM and KOT, although tissue cell population is controlled by a balance among these processes.…”

“…All these authors used different methods to evaluate PI. In some studies (7,11), the proliferative activity was assessed by PCNA labelling. PCNA expression is positive in all the cell cycle phases and in G0.…”

“…A higher proliferation activity in AM epithelium in relation to KOT epithelial lining has been demonstrated (7)(8)(9), even though opposite results have also been reported (10,11). Several studies have evaluated apoptosis and related apoptotic factors in the odontogenic epithelium of AM and epithelial lining of KOT (10)(11)(12)(13)(14)(15)(16)(17)(18)(19).…”

“…Several studies have evaluated apoptosis and related apoptotic factors in the odontogenic epithelium of AM and epithelial lining of KOT (10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Nevertheless, despite the fact that the cell population is controlled by the balance between cell proliferation and apoptosis, no study has evaluated simultaneously apoptotic and proliferation indexes in AMs and KOTs.…”