Expression of matrix metalloproteinases, metalloproteinase inhibitors and vascular endothelial growth factor in canine mast cell tumours: preliminary results

Introduction: Matrix metalloproteinases (MMPs) are a family of enzymes responsible for a wide range of proteolytic events. Previously published studies provided evidence of their involvement in cancer invasion and metastases. Canine cutaneous mast cell tumor (MCT) is among the most common neoplasms in dogs. Despite this, only studies related to MMPs protein expression and catalytic activity (zymography) have been published so far. Thus, in the present study mRNA levels of most relevant MMPs, their specific inhibitors as well as the vascular endothelial growth factor (VEGFA) were measured in canine MCTs. Materials and Methods: Canine MCTs surgical biopsies, their margins and control skin samples were considered. Tumors were classified according to Patnaik histological grading (grade I, II and III); mRNA levels of MMP2, -9, -13, -14, TIMP-1, -2, -3, RECK, VEGFA and VEGF164 were measured by using canine specific assays, UPL probes and a quantitative Real Time RT-PCR approach. Results: A significant, grading-dependent, increase of MMP9, MMP13, VEGFA and VEGF164 gene expression was noticed in MCTs; on the contrary, MMPs inhibitors (TIMP3 and RECK) showed an inhibitory trend, inversely correlated with the histological grading. Conclusions: Present results suggested MMP9 and VEGFA as potential indicator of malignancy in MCT and confirmed their participation in tumor invasion, metastasis and angiogenesis. Furthermore, TIMP3 and RECK lower mRNA amounts, noticed in aggressive MCTs, confirmed previous data found in human and other canine tumors. The confirmation of present results at the protein level, by means of immunohistochemistry and gel zymography, is actually in progress