The Expression Of COX-2 In Oral Papilloma, Oral Lichen Planus And Oral Squamous Cell Carcinoma

Cyclooxygenase, the rate-limiting enzyme required for the conversion of arachidonic acid to prostaglandins, is also called prostaglandin synthetase. Two cyclooxygenase isoforms have been identified and are referred to as COX-1 and COX-2.COX-1 is a constitutive enzyme, with homeostatic function. COX-2 is an inducible enzyme with low or non expression in physiological state, but the expression can be elevated by various stimuli such as growth factors, cytokines and tumor promoters. The recent studies indicate that COX-2 is increased in many types of inflammation and cancer tissues, but the exact mechanisms have not been fully understood. In this study, we adopted immunohistochemical technique to detect the expression of COX-2 protein in oral papilloma, oral lichen planus, oral squamous cell carcinoma and normal oral mucosa, then investigated the role of COX-2 in the progress of OP, OLP, OSCC and the significance in tumor carcinogenesis.Objective:To detect the expression of COX-2 in the tissue of NOM, OP, OLP and OSCC, and discuss the mechanism of the transformation from OP, OLP to cancer.Materials and Methods:The expression of COX-2 was determined by S-P immunohistochemical technique in the tissue of 10 cases of NOM,20 cases of OP,28 cases of OLP and 30 cases of OSCC. The results of positive expression rate were calculated and the mean optical density of were detected, then the results of COX-2 expression were analyzed according to their relations with multiple clinicopathological factors by SPSS software.Results:1) COX-2 mainly expressed in the cytoplasm or nuclear membrane of cells, which was positive brown staining granule. The positive rates of COX-2 in NOM, OP, OLP and OSCC were 0%,45%,67.9%,73.3% respectively. The total comparison of four group was substantial difference (χ2=19.020,P<0.005). There were no significant differences between the positive rates of COX-2 among OP. OLP and OSCC (P>0.05), which were higher than NOM (P<0.05). The MODs of COX-2 in NOM, OP, OLP and OSCC were 0.179±0.032,0.221±0.018,0.261±0.048,0.325±0.023, there were significant differences among the four groups (P<0.05).2) The positive rates of COX-2 in the simple type OLP and OLP with dysplasia were 56.25% and 83.3%, there was no significant difference between the two groups (P>0.05).The MODs of two groups were 0.231±0.038 and 0.285±0.017, the MOD of the OLP with dysplasia was higher than the simple type OLP (P<0.05)3) The positive rates of COX-2 inⅠ,Ⅱ,Ⅲdegree of OSCC different pathological grades were 71.4%,70.0% and 83.3%, there were no significant differences among the three groups (P>0.05), the MODs inⅠ,Ⅱ,Ⅲdegree were 0.272±0.018,0.281±0.013,0.338±0.025. There was no significant difference betweenⅠandⅡdegree (P>0.05), but were significant differences betweenⅡandⅢ,ⅠandⅢdegree (P<0.05), and the expression of COX-2 in poorly differentiated squamous cell carcinoma was significantly increased compared to that in moderately or well differentiated squamous cell carcinoma(P<0.05).4) The positive rates of COX-2 in patients without lymphatic metastasis and with lymphatic metastasis were 58.8% and 92.3%, there was a significant difference between the two group (P<0.05). The MODs were 0.258±0.036 and 0.318±0.043, patients with lymphatic metastasis were higher than those without signs of metastasis (P<0.05)5) The expression of COX-2 were not associated with OSCC of different clinical stages (P>0.05)6) The expression of COX-2 in OP, OLP and OSCC were not associated with patients'gender and age (P>0.05)Conclusions:1) The expression intensity of COX-2 in OP, OLP and OSCC increased in due order, and all higher than NOM. The MOD of the OLP with dysplasia was higher than the simple type OLP. Based on these findings, the abnormal expression of COX-2 may correlate with the transformation from OP, OLP to OSCC.2) The expression of COX-2 was associated with lymphatic metastasis and differentiation phenotypes of OSCC, but not with patients'clinical classification.3) The expression of COX-2 in OP, OLP and OSCC were not associated with patients'gender and age.