Expression And Significance Of Cyclooxygenase-2 In Ameloblastoma

ObjectiveAmeloblastoma (AB) is the most frequently occurring odontogenic tumor, the frequency of which is 59.3% in China.The benign tumor may progressively invade the jaw, relapse locally and transform malignantly, therefore, treated as a semi-malignancy tumor. The research expressed that the occurrence and development of ameloblastoma was related to excessive proliferation of cell and repress of apoptosis of cell. The balance of apoptosis and proliferation is out of moderate, which is more important in the occurrence and development of the tumor. Cyclooxygenase (COX) is an important rate - limiting enzyme in the synthesize process of the prostaglandin (PG). It can make arachidonic acid metaolist to all kinds of PG's outcome. And it joins into the process of pathologic physiology of the body. The body can be induced express by the pathologic appearance of the inflammation and tumor. The research of recent years expresses that COX-2 acting as the induced COX besides its importance in inflammation, has something with occurrence, development, diversion and invasion of many tumors.The present study aims to measure the expression of COX-2 mRNA and proteinum in AB and to investigate the molecular mechanisms in the regulation of COX-2; and examine the association between COX-2 and the clinicopathological characteristics of the tumor specimens in AB to provide some theoretic basis for the diagnosis, therapy and prognosis of AB.Materials and Methdods1. Immunohistochemical stainingA total of 77 AB (primary AB 49 cases, recurrent AB 28 cases), 6 ameloblastic carcinomas, 9 para-tumor mucosas and 9 normal oral mucosas were collected from School of Stomatology and the First Affiliated Hospital of China Medical University between 1987-2005. The AB included 34 follicular patterns, 20 plexiform patterns, 5 acanthomatous types, 4 granular types, 1 basal cell type, 8 unicystic ameloblastomas, and 5 peripheral ameloblastomas. I use the immunohistochemical staining S-P to observe the change of the COX-2.2. RT-PCR and Western Blot15 AB and 3 normal oral mucosas were collected form School of Stomatology between 2004-2005 to measure the expression of COX-2 mRNA and proteinum. The AB included 2 follicular patterns, 6 plexiform patterns, 4 acanthomatous types, 2 basal cell types, 1 desmoplastic type, 7 males, 8 females.Results1. Immunohistochemical stainingThe immunohistochemical staining of COX-2 was observed in 81.8% (63/77) of AB tissues, in 100% (6/6) of ameloblastic carcinomas, in 44.4% (4/9) of normal mucosas, in 77.8% (7/9) of para-tumor mucosas. They were significantly different with each other (P<0.05). COX-2 was positive expressed in the plasma of peripheral cells, stellate central cells, phlogotic cells, vascular endothelial cells and fibrocyte, negative in the granular cells in AB. The normal mucosas and para-tumor mucosas expressed in the para-tumor mucosas.2. RT-PCR and Western BlotThe COX-2 was overexpressed in the AB. The level of the COX-2 was very low in the normal oral mucosas. So there was significant difference between them (P<0.05), and there was no correlation between mRNA and proteinum (P>0.05).Conclusion1.COX-2 mRNA and proteinum were all overexpressed in the AB, and it expressed slight in the normal mucosas.2.COX-2 involved in the occurrence and development of the AB, the ability of invasion and canceration of AB were correlated with the overexpression of COX-2.