Isabel Pires

The role of Cox-2 expression in the prognosis of dogs with malignant mammary tumours.

Immunohistochemical detection of Cyclooxygenase (Cox)-1 and -2 enzymes in canine mammary tumours (CMT) has recently been described. However, the prognostic value of their expression needs to be established. The aim of this study was to investigate Cox (-1 and -2) prognostic value in malignant CMT by evaluating its correlation with clinicopathological parameters (tumour size, histological type, necrosis, lymph node metastasis) and with Disease Free Survival (DFS) and Overall Survival (OS). Twenty seven female dogs with malignant tumours were included. Cox-2 expression was associated with lymph node metastasis at surgery time, development of distant metastasis during follow-up (p=0.038), DFS (p=0.03) and OS (p=0.04). Multivariate survival analysis showed that Cox-2 did not retain its significance as an independent prognostic factor. For Cox-1 expression, no statistically significant association was observed. Present study suggests the usefulness of testing Cox-2 specific inhibitors as part of an adjuvant therapy in female dogs with malignant mammary neoplasias.

COX-2 over-expression correlates with VEGF and tumour angiogenesis in canine mammary cancer

This study was designed to investigate the possible roles of cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) in canine mammary cancer angiogenesis. Immunohistochemistry was performed on 70 tumours (28 benign and 42 malignant) in order to detect COX-2 and VEGF expression. Microvessel density (MVD) was determined by CD31 immunolabelling to assess tumour angiogenesis. There was a significantly higher expression of COX-2 (P<0.001), VEGF (P<0.001) and MVD (P<0.001) in malignant compared to benign tumours. In the malignant group, the MVD of COX-2 positive tumours was significantly higher than that of COX-2 negative tumours (P=0.026). A similar association was observed for VEGF (P<0.001) positive tumours. The results from this study suggested that over-expression of COX-2 and VEGF may contribute to increased angiogenesis and aggression in malignant tumours.

COX-1 and COX-2 expression in canine cutaneous, oral and ocular melanocytic tumours.

In order to evaluate the potential value of non-steroidal anti-inflammatory drugs (NSAIDs) in the treatment of canine malignant melanoma, expression of cyclooxygenase (COX)-1 and COX-2 was determined in 20 cutaneous, nine oral and two ocular malignant melanomas, and in nine cutaneous melanocytomas. Almost all tumours expressed COX-1, but COX-2 expression was restricted to the malignant tumours being found in 11 of the 20 cutaneous malignant melanomas, all oral malignant melanomas and in one of two ocular malignant melanomas. COX-1 expression did not differ significantly between benign and malignant skin lesions, but COX-2 expression was significantly greater in cutaneous malignant melanoma compared with melanocytoma (P=0.047). COX-2 labelling was particularly intense in the more highly malignant oral tumours. The results of the study suggest that NSAIDs, particularly COX-2 inhibitors, may be useful in the treatment of canine malignant melanoma.

A Role for T-Lymphocytes in Human Breast Cancer and in Canine Mammary Tumors

Chronic inflammation in the tumor microenvironment has a prominent role in carcinogenesis and benefits the proliferation and survival of malignant cells, promoting angiogenesis and metastasis. Mammary tumors are frequently infiltrated by a heterogeneous population of immune cells where T-lymphocytes have a great importance. Interestingly, similar inflammatory cell infiltrates, cytokine and chemokine expression in humans and canine mammary tumors were recently described. However, in both species, despite all the scientific evidences that appoint for a significant role of T-lymphocytes, a definitive conclusion concerning the effectiveness of T-cell dependent immune mechanisms has not been achieved yet. In the present review, we describe similarities between human breast cancer and canine mammary tumors regarding tumor T-lymphocyte infiltration, such as relationship of TILs and mammary tumors malignancy, association of ratio CD4+/ CD8+ T-cells with low survival rates, promotion of tumor progression by Th2 cells actions, and association of great amounts of Treg cells with poor prognostic factors. This apparent parallelism together with the fact that dogs develop spontaneous tumors in the context of a natural immune system highlight the dog as a possible useful biological model for studies in human breast cancer immunology.

Tuberculosis in goats

WE read with interest the recent papers about goat tuberculosis (TB) ([Crawshaw and others 2008][1], [Daniel and others 2009][2]). Reports of caprine TB are increasing in several countries. Here, we describe a TB outbreak in goats in Portugal, disclosed between September 2007 and April 2008,

EGFR and microvessel density in canine malignant mammary tumours.

The epidermal growth factor receptor (EGFR) is a transmembrane tyrosine kinase receptor which has been shown to have an important role in human breast cancer. Its role appears to be associated with increased angiogenesis and metastasis. In order to clarify its role in canine mammary tumours (CMT), 61 malignant neoplasms were studied by using immunohistochemistry, comparing expression of EGFR, microvessel density (MVD) by CD31 immunolabelling and characteristics of tumour aggressiveness. High EGFR immunoexpression was statistically significantly associated with tumour size, tumour necrosis, mitotic grade, histological grade of malignancy and clinical stage. High CD31 immunoreactivity was statistically significantly associated with tubule formation, histological grade of malignancy and clinical stage. A positive correlation between EGFR and CD31 immunoexpression (r = 0.843; P < 0.001) was also observed. Results suggest that an over-expression of EGFR may contribute to increased angiogenesis and aggression in malignant CMT, presenting the possibility of using EGFR inhibitors in the context of metastatic disease treatment.

Prognostic value of tumour-associated macrophages in canine mammary tumours

Tumour-associated macrophages (TAMs) have already been associated in human breast cancer to a poor prognosis. As a part of a tumoural microenvironment, TAMs have an important contribution influencing neoplastic progression. Hitherto, in canine mammary tumours (CMT) the prognostic value of TAMs has not been reported. In this study, MAC387 immunohistochemical expression was evaluated in 59 CMTs (20 benign and 39 malignant). The TAM value was significantly higher in malignant than benign CMT (P = 0.011). In malignant CMT, TAMs were associated with skin ulceration (P = 0.022), histological type (P = 0.044), nuclear grade (P = 0.031) and tubular differentiation (P = 0.042). The survival analysis revealed a significant association between tumours with higher levels of TAMs and the decrease in overall survival (P = 0.030). TAMs have proven to have a prognostic value. These findings suggest the future possibility of using TAMs as a novel therapeutic target in CMT.

Tumour-associated macrophages are associated with vascular endothelial growth factor expression in canine mammary tumours

Tumour-associated macrophages (TAMs) have been implicated in carcinogenesis including an important role in angiogenesis. In this study, we describe the relationship between TAMs and angiogenesis in canine mammary tumours (CMT). Formalin-fixed paraffin-embedded CMT samples [(n = 128: malignant (n = 97) and benign (n = 31)] were submitted to immunohistochemical staining to detect MAC387, vascular endothelial growth factor VEGF and CD31 expression. A statistical analysis was carried out to assess possible associations with clinicopathological variables and biological markers of tumour angiogenesis. TAMs, detected by MAC387 expression, were significantly associated with malignant CMT (P < 0.001) and VEGF positive tumours (P = 0.002) and also associated with VEGF expression within malignant CMT (P = 0.043). Associations with clinicopathological variables were found between TAMs and the presence of infiltrative growth (P = 0.031), low tubule formation (P = 0.040) and lymph node metastasis (P = 0.016). The results support the hypothesis that TAMs influence angiogenesis in CMT suggesting TAMs may represent a therapeutic target in this disease.

Study of c-kit immunoexpression in canine cutaneous melanocytic tumors.

Melanocytic tumors occur as much in humans as in dogs and are frequently associated with receptor tyrosine kinase dysregulation. The transmembrane c-kit protein is a receptor tyrosine kinase that is crucial in melanocytic homeostasis and, when mutated, is associated with tumor development in those cells. In human studies, its expression is generally detected in melanocytomas and primary malignant melanomas, being lost with tumor progression and metastasis. In this study, we aimed to analyze c-kit expression in canine cutaneous melanocytic tumors and its association with tumor behavior, in order to investigate the dog’s potential in comparative pathology and c-kit’s potential in the diagnosis of these tumors. The expression of c-kit was evaluated immunohistochemically in 39 canine cutaneous melanocytic tumors and scored in terms of the labeling location, extension, and intensity. The labeling location was essentially cytoplasmic, and the labeling extension and intensity were generally higher in melanocytomas (83.3% diffuse-labeled cells) than those in malignant melanomas (22.2% negative-labeled cells). The differences found in the labeling extension were statistically significant (P<0.001). There was no association between c-kit immunoexpression in malignant melanomas and the clinicopathological criteria, except between the labeling intensity and the degree of intralesional pigmentation (P=0.048). Our results for labeling extension are in agreement with similar human studies, reinforcing the dog’s potential as a model organism for investigation in this type of cancer. In addition, the loss of c-kit expression in malignant melanomas might be a criterion of tumor aggressiveness, indicating that this receptor may be useful in the diagnosis of these tumors.

Epithelioid hemangiosarcomas of the bovine urinary bladder: a histologic, immunohistochemical, and ultrastructural examination of four tumors.

Epithelioid hemangiosarcoma is a specific variant of hemangiosarcoma that has recently been recognized in domestic animals. These malignant vascular neoplasms histologically resemble, and may be mistaken for, carcinomas. Four epithelioid hemangiosarcomas in the urinary bladders of 4 cows with severe enzootic hematuria are described in the current study. Grossly, the vesicular mucosa of the urinary bladder of each cow contained a single red elevated nodule. Histologically, each neoplasm was composed of short strands, cords, or nests of epithelioid, round, or slightly spindle-shaped endothelial cells that formed small vascular structures. Neoplastic cells were immunohistochemically positive for factor VIII–related antigen and vimentin, and were negative for cytokeratin and desmin. Ultrastructurally, the neoplastic cells often contained cytoplasmic intermediate filaments, a prominent granular endoplasmic reticulum, a Golgi complex, mitochondria, marked pinocytotic activity, and rare Weibel-Palade bodies. These neoplasms were diagnosed as epithelioid hemangiosarcomas based on their histologic, immunohistochemical, and ultrastructural features. The present report widens the spectrum of mesenchymal tumors of the bovine urinary bladder and aids in the characterization of these vascular neoplasms.