RESUMO
OBJECTIVES: Tissue inhibitor of metalloproteinase-3 (TIMP3) antagonizes matrix metalloproteinase activity and can suppress tumor growth, angiogenesis, invasion, and metastases. In the present study, the involvement of TIMP3 in the tumorigenesis of 34 pancreatic adenocarcinomas was evaluated. METHODS: Immunohistochemistry, methylation-specific PCR, and RNA expression analysis (RT-PCR) of TIMP3 were performed in 34 resected and microdissected primary pancreatic adenocarcinomas. RESULTS: Immunohistochemistry showed loss or strongly reduced protein expression in 17 of 34 pancreatic adenocarcinomas (50%) that corresponded to loss of TIMP3-RNA-expression. Promoter hypermethylation was identified in 2 of 34 tumors (6%). It was tumor specific and corresponded to a loss of TIMP3 protein expression. TIMP3 alterations did not correlate with any clinical feature such as tumor size or survival. CONCLUSION: TIMP3 seems to play an important role in the tumorigenesis of primary pancreatic adenocarcinomas. In contrast to other tumors, hypermethylation seems not to be the key mechanism for the inactivation of TIMP3. Other methods of gene inactivation need to be identified.