Increased expression of tissue inhibitor of metalloproteinase-1 correlates with improved outcome in canine cutaneous mast cell tumours.

Canine mast cell tumour (MCT) is a biologically heterogeneous disease. The extracellular matrix degradation promoted by matrix metalloproteinases (MMPs) has been studied in an attempt to elucidate the mechanisms involved in the biological behaviour of tumours. The aim of this study was to characterize the expression of MMP-2 and -9 and tissue inhibitors of metalloproteinase (TIMP)-1 and -2 in canine cutaneous MCTs and to evaluate their prognostic values. Immunohistochemical staining for MMP-2, MMP-9, TIMP-2 and TIMP-1 was performed in 46 canine cases of MCTs. TIMP-1 expression showed an independent prognostic value for post-surgical survival and disease-related mortality. Dogs with MCTs showing less than 22.9% mast cell TIMP-1 positivity were more prone to die because of the disease and had a shorter post-surgical survival. This article suggests the involvement of TIMP-1 in MCT progression, by contributing to a good outcome in patients with MCTs.

Evaluation of cyclooxygenase-2 expression in canine mast cell tumours.

Mast cell tumours (MCTs) are among the most common cutaneous neoplasms in dogs and have a highly variable clinical behaviour. Cyclooxygenase (Cox) catalyzes the rate-limiting step in prostanoid biosynthesis and has recently gained attention as a prognostic factor and therapeutic target in human and animal oncology. In order to evaluate the potential value of non-steroidal anti-inflammatory drugs (NSAIDs) in the treatment of canine MCTs, expression of Cox-2 was determined in 49 such tumours (14 of grade I, nine of grade II and 22 of grade III). Cox-2 was expressed by 86% of the tumours studied. The percentage of labelled cells ranged from isolated positive cells throughout the tumour (n=8) to localized foci of labelled cells (n=3) or diffuse labelling of >50% of the cells (n=31). The intensity of Cox-2 labelling ranged from weak (n=4) to moderate (n=16) and strong (n=22) and was greatest at the advancing margin of the tumour. The intensity of Cox-2 labelling was significantly different between the three histological groups (P=0.018). However, no significant differences were noted for the percentage of Cox-2 positive cells (P=0.122) and for the immunoreactivity score (P=0.348) between the histological grades. The results of this study suggest that NSAIDs, particularly Cox-2 inhibitors, may be of value in the treatment of canine MCTs.

Matriptase expression in the normal and neoplastic mast cells.

Matriptase, a type II transmembrane serine protease, is distributed in almost all normal human epithelium. Several studies have demonstrated that matriptase expression is correlated with tumor progression in epithelium-derived cancer cells. Mast cells, which originate from pluripotent hematopoietic cells in the bone marrow, can produce and store almost cellular-specific neutral serine proteases, such as tryptase and chymase, and are functionally involved in both the immediate hypersensitivity response and anaphylactic shock. Mast cells are significantly increased in several neoplasms, indicating that they most likely play a role in degrading the tissue matrix. Recently, trypsin has been revealed to activate the latent matriptase on the surface of several human cancer cell lines, suggesting that matriptase and trypsin cooperatively function in extracellular proteolysis. In our study, almost all mast cells in tissues throughout the body stained positive for matripase. Matripase was also found in neoplastic mast cells. To our knowledge, this is the first time that matriptase has been shown to be expressed by mast cells. Therefore, we suggest that this expression of matriptase may not only be useful as an additional marker for mast cells but also be involved in their physiopathological function.