OBJECTIVETo examine the expression of MMPs and TIMPs in pleomorphic adenoma of salivary gland and to investigate the relationship between the expression and the biological behaviour of the tumor.

METHODSTwenty-three cases of pleomorphic adenoma were divided into active type and common type according to their biological behavior. Immunohistochemistry for MMP-2, MMP-9, TIMP-1, TIMP-2 and gelatin zymography analysis were performed in these 23 cases and in 6 malignant and 6 benign salivary gland tumors.

RESULTSThe immunoreactivity of MMP-2 protein and MMP-2/TIMP-1, 2 ratio were significantly higher in active pleomorphic adenoma than in common pleomorphic adenoma (P = 0.028, P = 0.009, P = 0.045). The expression of active MMP-2, proMMP-9 and active MMP-9 were significantly higher in active pleomorphic adenoma than in common pleomorphic adenoma (P = 0.034, P = 0.021, P = 0.001). There was no significant difference in expression of MMP-2, MMP-9, TIMP-1 and TIMP-2 between the salivary malignant tumor and active pleomorphic adenoma, also between the salivary benign tumor and common pleomorphic adenoma.

CONCLUSIONSThe expression of MMPs and TIMPs in active pleomorphic adenoma is similar to that in salivary carcinomas, and the expression in common pleomorphic adenoma also resembled to that in salivary adenoma. The expression of MMP-2, 9 and TIMP-1, 2 is related to the biological behavior of pleomorphic adenoma of salivary gland.