Matrix metalloproteinases and their inhibitors in canine mammary tumors

BMC Veterinary Research, Jul 2011

Background Malignant canine mammary tumors represent 50% of all neoplasms in female dogs. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are thought to be involved in tumor progression, and they are also associated with the reactive stroma, which provides structural and vascular support for tumor growth. Results MMP-2, MMP-9 and MT1-MMP were expressed at both the mRNA and protein levels in tumor samples. MMP-2 and MMP-9 immunohistochemical reactions were evident both in the epithelial tumor cells and in the stromal compartment to varying degrees; in particular, the intensity of the MMP-2 staining was stronger in the stromal fibroblasts close to epithelial tumor cells in simple carcinomas than in adenomas. These data were supported by gelatin-zymography; bands for the active form of MMP-2 were found in 94% of carcinoma samples, compared with 17% of benign tumor samples. The gene expression and immunohistochemical results for MT1-MMP were comparable to those for MMP-2. The immunoreactivity for MMP-13 and TIMP-2 was lower in carcinomas than in adenomas, confirming the mRNA data for MMP-13 and the other MMP inhibitors that were evaluated. The active form of MMP-9, but not the active form of MMP-2, was identified in the plasma of all of the tested dogs. Conclusions Our findings suggest that MMP-9, MMP-2 and MT1-MMP, which are synthesized by epithelial cancer cells and cancer-associated fibroblasts, play an important role in malignant canine mammary tumors. The reduction of MMP-13 and TIMP-2 could also be a significant step in malignant transformation. MMP-2 and MT1-MMP could be further evaluated as future biomarkers for predicting the progression and prognosis of canine mammary tumors.

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Matrix metalloproteinases and their inhibitors in canine mammary tumors

BMC Veterinary Research Matrix metalloproteinases and their inhibitors in canine mammary tumors Luca Aresu 0 3 Mery Giantin 0 3 Emanuela Morello 2 Marta Vascellari 1 Massimo Castagnaro 0 3 Rosa Lopparelli 0 3 Vanessa Zancanella 0 3 Anna Granato 1 Spiridione Garbisa 4 Arianna Aricò 0 3 Alice Bradaschia 4 Franco Mutinelli 1 Mauro Dacasto 0 3 0 Dipartimento di Sanità Pubblica, Patologia Comparata e Igiene Veterinaria, Facoltà di Medicina Veterinaria, Università degli Studi di Padova , Padova , Italy 1 Histopathology Department, Istituto Zooprofilattico Sperimentale delle Venezie , Viale dell'Università 10, 35020 Legnaro (PD) , Italy 2 Dipartimento di Patologia Animale, Facoltà di Medicina Veterinaria, Università degli Studi di Torino , Italy 3 Dipartimento di Sanità Pubblica, Patologia Comparata e Igiene Veterinaria, Facoltà di Medicina Veterinaria, Università degli Studi di Padova , Padova , Italy 4 Dipartimento di Scienze Biomediche Sperimentali, Università di Padova , viale Colombo 3, Padova , Italy Background: Malignant canine mammary tumors represent 50% of all neoplasms in female dogs. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are thought to be involved in tumor progression, and they are also associated with the reactive stroma, which provides structural and vascular support for tumor growth. Results: MMP-2, MMP-9 and MT1-MMP were expressed at both the mRNA and protein levels in tumor samples. MMP-2 and MMP-9 immunohistochemical reactions were evident both in the epithelial tumor cells and in the stromal compartment to varying degrees; in particular, the intensity of the MMP-2 staining was stronger in the stromal fibroblasts close to epithelial tumor cells in simple carcinomas than in adenomas. These data were supported by gelatin-zymography; bands for the active form of MMP-2 were found in 94% of carcinoma samples, compared with 17% of benign tumor samples. The gene expression and immunohistochemical results for MT1MMP were comparable to those for MMP-2. The immunoreactivity for MMP-13 and TIMP-2 was lower in carcinomas than in adenomas, confirming the mRNA data for MMP-13 and the other MMP inhibitors that were evaluated. The active form of MMP-9, but not the active form of MMP-2, was identified in the plasma of all of the tested dogs. Conclusions: Our findings suggest that MMP-9, MMP-2 and MT1-MMP, which are synthesized by epithelial cancer cells and cancer-associated fibroblasts, play an important role in malignant canine mammary tumors. The reduction of MMP-13 and TIMP-2 could also be a significant step in malignant transformation. MMP-2 and MT1-MMP could be further evaluated as future biomarkers for predicting the progression and prognosis of canine mammary tumors. - Background Mammary neoplasia is one of the most common tumors in dogs, and malignant types occur in approximately half of canine mammary tumors. Invasion and metastasis are typical features of carcinomas [1,2]. The physical process of tumor invasion involves cellular disengagement from the local microenvironment, followed by degradation of the surrounding matrix and cellular movement [3]. Invasion and metastasis of malignant tumor cells is a complex multistep process, in which the initial events are disruption of the extracellular matrix (ECM) and invasion of the basement membrane. In addition, fibroblasts in the stroma of cancerous tissue can promote the proliferation and invasion of carcinoma cells and induce angiogenesis via the secretion of several ECM molecules, proteases and cytokines [4,5]. This mechanism is highly organized and involves the selective action of a group of proteases that are active at neutral pH and can collectively degrade most, if not all, components of the ECM [6,7]. These proteases are known as matrix metalloproteinases (MMPs), and they hydrolyze the protein and proteoglycan components of the ECM. Under physiological conditions, MMPs are expressed by a variety of cells and tissues. MMPs are also involved in a number of pathological processes and are thought to be responsible for the accelerated ECM breakdown that is associated with tumor invasion and metastasis [8]. Gelatinases are a subgroup within the MMP family and include MMP-2 and MMP-9. MMPs play the same role in dogs as in humans, controlling tumor invasion and progression in different tumors [9-14]. MMP-2 and MMP-9 are secreted in an inactive form, which is called a zymogen or a pro-MMP. Several types of inhibitors, called tissue inhibitors of MMPs (TIMPs), regulate MMP activity. TIMPs also function as MMP activators [15]. To exert their inhibiting or activating functions, TIMP-1 and TIMP-2 preferentially bind to MMP-9 or MMP-2, respectively [16,17]. The unbalanced activities of MMPs and TIMPs are involved in tumor progression [18]. Evaluation of the activities of TIMP-1, TIMP-2 and TIMP-3 in canine mammary tumor samples by reverse zymography has shown that low activity can be correlated with a (...truncated)


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Luca Aresu, Mery Giantin, Emanuela Morello, Marta Vascellari, Massimo Castagnaro, Rosa Lopparelli, Vanessa Zancanella, Anna Granato, Spiridione Garbisa, Arianna Aricò, Alice Bradaschia, Franco Mutinelli, Mauro Dacasto. Matrix metalloproteinases and their inhibitors in canine mammary tumors, BMC Veterinary Research, 2011, pp. 33, 7, DOI: 10.1186/1746-6148-7-33