Increased expression of cyclooxygenase-2 and Ki-67 are associated with malignant transformation of pleomorphic adenoma.
OBJECTIVE
In the present study, we attempted to identify cyclooxygenase-2 (COX-2) expression and Ki-67 index in carcinoma ex-pleomorphic adenoma (Ca ex-PA) using quantitative immunohistochemical analysis and to compare the benign component of the neoplasia. We also aimed to relate the overexpression of COX-2 with the pathways of malignant transformation of Ca ex-PA as evidenced by distinct morphological features.


METHODS
Forty Ca ex-PA from patients treated at Department of Otolaryngology, Yokohama City University Medical Center, Yokohama, Japan, from 1999 to 2005, were selected. All Ca ex-PA showed only one malignant histological component: adenocarcinoma (23 cases), adenoid-cystic carcinoma (10), epithelial-myoepithelial carcinoma (7). The tissues were stained with monoclonal antibodies to COX-2 and Ki-67. The results were analyzed using quantitative immunohistochemical analysis. We also analyzed the association of the histological classification of the carcinomatous component.


RESULTS
In the immunohistochemical analysis of COX-2 and Ki-67 index, significant increase was observed in Ca ex-PA, especially with adenocarcinoma, compared to pleomorphic adenoma and sialadenitis. Quantitative assessment is more sensitive as a measure of cellular protein content as compared to standard optical density measurement.


CONCLUSIONS
The data support the hypothesis that increased COX-2 expression is associated with early events in malignant transformation of pleomorphic adenoma.
Katori
Hideaki
H
Department of Otolaryngology, Yokohama City Minato Red Cross Hospital, 3-12-1 Shin-yamashita, Naka-ku, Yokohama 231-8682, Japan. hhkatori@yahoo.co.jp
Nozawa
Akinori
A
Tsukuda
Mamoru
M
D008949:Adenoma, Pleomorphic / Q000276:immunology* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000276:immunology; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D051546:Cyclooxygenase 2 / Q000276:immunology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010307:Parotid Neoplasms / Q000276:immunology* / Q000473:pathology; D012468:Salivary Gland Neoplasms / Q000276:immunology* / Q000473:pathology
D000906:Antibodies; D019394:Ki-67 Antigen; D051546:Cyclooxygenase 2