title: Immunohistochemical analysis of COX-2 expression in dentigerous cyst, keratocystic odontogenic tumor and ameloblastoma: A comparative study.
abstract: BACKGROUND
  Cyclo-oxygenase-2 (COX-2) is an early response gene that is induced by growth factors, oncogenes and carcinogens and its expression is increased in various tumors. Increased expression of COX-2 plays a significant role in the development and growth of tumors by interfering in biological processes such as cell division, cellular immunity, cell adhesion, apoptosis, and angiogenesis. This study aimed to investigate the immunohistochemical expression of COX-2 in keratocystic odontogenic tumor (KOT) in comparison with ameloblastoma and dentigerous cyst with regards to different clinical behavior and histopathological features of these lesions.
  
  
  METHODS
  Paraffined blocks of 45 cases including 15 cases of dentigerous cyst, 15 cases of KOT and 15 cases of ameloblastoma were stained with immunohistochemical method for COX-2. Five high-power fields of each sample were evaluated to determine the percentage of stained cells and the intensity of staining. Degree of immunoreactivity was obtained from the sum of two. Statistical evaluation was performed by the Kruskal-Wallis and ANOVA Mann-Whitney test (P < 0.05).
  
  
  RESULTS
  Overexpression of COX-2 in ameloblastoma and KOT was observed compared with dentigerous cyst (P < 0.001). However, no significant difference was observed between the expression of COX-2 in ameloblastoma and KOT (P = 0.148).
  
  
  CONCLUSIONS
  The COX-2 expression in odontogenic tumors such as ameloblastoma and cystic neoplasm with aggressive behavior such as KOT increases. However, it does not seem that COX-2 affects the development and growth of cysts with noninvasive behavior like dentigerous cyst.
authors.affiliation: Oral and Maxillofacial Pathology Department, Dental Materials Research Center, Dental Faculty, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Seyedmajidi
authors.affiliation: Pathology Department, Cellular and Molecular Biology Research Center, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Shahryar
authors.initials: S
authors.lastname: Shafaee
authors.affiliation: Department of Pathology, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Sepideh
authors.initials: S
authors.lastname: Siadati
authors.affiliation: Students Research Committee, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Elham Alizadeh
authors.initials: EA
authors.lastname: Moghaddam
authors.affiliation: Students Research Committee, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Nafiseh
authors.initials: N
authors.lastname: Ghasemi
authors.affiliation: Non-communicable Pediatrics Diseases Research Center, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Bijani
authors.affiliation: Students Research Committee, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Najafi
keywords: Ameloblastoma; cyclo-oxygenase-2; dentigerous cyst; immunohistochemistry; keratocystic odontogenic tumor