A.J.F. Matos

Identification of prognostic factors in canine mammary malignant tumours: a multivariable survival study

BackgroundAlthough several histopathological and clinical features of canine mammary gland tumours have been widely studied from a prognostic standpoint, considerable variations in tumour individual biologic behaviour difficult the definition of accurate prognostic factors. It has been suggested that the malignant behaviour of tumours is the end result of several alterations in cellular physiology that culminate in tumour growth and spread. Accordingly, the aim of this study was to determine, using a multivariable model, the independent prognostic value of several immunohistochemically detected tumour-associated molecules, such as MMP-9 and uPA in stromal cells and Ki-67, TIMP-2 and VEGF in cancer cells.ResultsEighty-five female dogs affected by spontaneous malignant mammary neoplasias were followed up for a 2-year post-operative period. In univariate analysis, tumour characteristics such as size, mode of growth, regional lymph node metastases, tumour cell MIB-1 LI and MMP-9 and uPA expressions in tumour-adjacent fibroblasts, were associated with both survival and disease-free intervals. Histological type and grade were related with overall survival while VEGF and TIMP-2 were not significantly associated with none of the outcome parameters. In multivariable analysis, only a MIB-1 labelling index higher than 40% and a stromal expression of MMP-9 higher than 50% retained significant relationships with poor overall and disease-free survival.ConclusionsThe results of this study indicate that MMP-9 and Ki-67 are independent prognostic markers of canine malignant mammary tumours. Furthermore, the high stromal expressions of uPA and MMP-9 in aggressive tumours suggest that these molecules are potential therapeutic targets in the post-operative treatment of canine mammary cancer.

Transfer of Multidrug-Resistant Bacteria Between Intermingled Ecological Niches: The Interface Between Humans, Animals and the Environment

The use of antimicrobial agents has been claimed to be the driving force for the emergence and spread of microbial resistance. However, several studies have reported the presence of multidrug-resistant bacteria in populations exposed to low levels of antimicrobial drugs or even never exposed. For many pathogens, especially those organisms for which asymptomatic colonization typically precedes infection (e.g., Enterococcus spp. and Escherichia coli), the selective effects of antimicrobial use can only be understood if we considerer all biological and environmental pathways which enable these bacteria, and the genes they carry, to spread between different biomes. This ecological framework provides an essential perspective for formulating antimicrobial use policies, precisely because it encompasses the root causes of these problems rather than merely their consequences.

Prognostic studies of canine and feline mammary tumours: the need for standardized procedures.

For several years, veterinary oncologists have been struggling with the prognosis of mammary tumours in dogs and cats. Translation of tumour characteristics into prognostic information is an invaluable tool for the use of the most appropriate therapies, as well as for planning innovative therapeutic trials. Moreover, canine and feline spontaneous mammary gland tumours are good models for the study of human breast cancer. Collecting and interpreting information regarding the prognosis of canine and feline mammary tumours is difficult due to the fact that different methods have been applied to study various components and characteristics. This review identifies some of the challenges of prognostic studies of spontaneous canine and feline mammary tumours and suggests standardized procedures to overcome these challenges and facilitate reproducibility and assessment of results.

E‐cadherin, β‐catenin, invasion and lymph node metastases in canine malignant mammary tumours

Recent studies of canine malignant mammary tumours suggest that reduction of E‐cadherin and/or β‐catenin correlates with invasive behaviour and lymph node metastasis. The aims of this study were to examine the interrelationships between the expression of E‐cadherin and β‐catenin, and the relationship between the expression of E‐cadherin and/or β‐catenin and the mode of growth and metastatic capacity of canine malignant mammary tumours. 90 spontaneous malignant tumours and local and regional lymph nodes were studied. A significant relationship was evidenced between membranous expression of E‐cadherin and β‐catenin (p=0.0027), but not between E‐cadherin and cytoplasmic β‐catenin. Only E‐cadherin as a separate factor was significantly related to tumour invasion (p=0.0072) and lymph node metastasis (p=0.0001). Neither membranous nor cytoplasmic β‐catenin expression was significantly related to either of these phenomena.

COX-2 expression in canine normal and neoplastic mammary gland.

COX-2 expression was examined immunohistochemically in samples of normal canine mammary tissue (n=22) and benign (n=36) and malignant (n=45) mammary tumours including metastases (n=12). COX-2 was constitutively expressed in normal mammary tissue with membranous apical labelling of glandular epithelium, suggesting a role for this molecule in normal mammary physiology. By contrast, in neoplastic lesions and in adjacent non-neoplastic mammary tissue COX-2 was expressed in the cytoplasm of epithelial cells, suggesting that internalization of the molecule is associated with oncogenesis. Marked expression of COX-2 was observed in 8.3% of benign neoplasms and in 42.2% of malignant neoplasms, mainly in poorly differentiated areas. The majority of metastatic lesions (58.3%) exhibited strong COX-2 labelling and in almost all cases (83.3%) the labelling intensity was similar or stronger to that of the primary neoplasm. This finding is consistent with the hypothesis that COX-2 metabolites are important promoters of angiogenesis and invasiveness and therefore contribute to metastatic spread.

Detection of lymph node micrometastases in malignant mammary tumours in dogs by cytokeratin immunostaining.

A series of 131 local and regional lymph nodes from 40 dogs with malignant mammary tumours were evaluated by staining with haematoxylin and eosin and immunohistochemically for antibodies to pancytokeratin (AE1/AE3) and cytokeratin 14. The immunohistochemical tests detected occult micrometastases in 9·2 per cent of the lymph nodes that were negative by haematoxylin and eosin staining. Under the modified TNM classification of canine mammary tumours, these results raised the clinical stage of 12·5 per cent of the affected dogs. However, if the latest TNM classification of human breast cancer had been applied, none of the animals would have been reclassified.

Immunohistochemical expression of vascular endothelial growth factor in canine mammary tumours.

The histopathological and clinical aspects of canine mammary tumours (CMTs) have been widely studied, but the variation in the biological behaviour of these neoplasms hampers the identification of prognostic factors. Sustained angiogenesis has been suggested to be one of the most important factors underlying tumour growth and invasion. This process involves the action of several growth factors including vascular endothelial growth factor (VEGF). The present study characterizes the relationship between immunohistochemical expression of VEGF and gross (e.g. size and tissue fixation) and microscopical (e.g. type, growth, necrosis, lymphoid infiltration, lymph node metastasis, histological grade and proliferation index) features of CMTs. Forty-eight benign and 64 malignant CMTs were evaluated. Statistical analysis failed to show a significant relationship between VEGF expression and the pathological features, suggesting that VEGF expression occurs in both benign and malignant tumours and is independent of histological type, proliferation, tissue invasion or local metastatic capacity.

Frequency of dog erythrocyte antigen 1.1 expression in dogs from Portugal

BACKGROUND Dog erythrocyte antigen (DEA) 1.1 is the antigen considered most responsible for severe hemolysis owing to incompatible blood transfusions in previously sensitized dogs. Few reports describe the frequency of DEA 1.1 expression in European dogs, and there are no reports in dogs from Portugal. OBJECTIVE The aims of this study were to identify the frequency of DEA 1.1 expression in Portuguese dogs, to examine the relationship between phenotypic traits and expression of this blood group, and to assess the risk of transfusing blood that is not typed or cross-matched. METHODS Expression of DEA 1.1 was determined in 274 dogs using a migration gel test. Weight, sex, breed, and hair length and color were recorded for each dog. Results were analyzed by descriptive statistical analysis, probabilistic analysis, and χ(2)-tests. RESULTS Of 274 dogs, 56.9% were DEA 1.1-positive and 43.1% were DEA 1.1-negative. All Boxers, German Shepherds, and Dobermans were DEA 1.1-negative, whereas all Saint Bernards, 88.9% of Golden Retrievers, 88.2% of Rottweilers, and 61.4% of mixed breed dogs were DEA 1.1-positive. A significant relationship between DEA 1.1 expression and phenotypic traits was not found. The probability of sensitization of recipient dogs following first-time transfusion with blood that was not typed or cross-matched was 24.5%; the probability of an acute hemolytic reaction following a second transfusion with blood from any other donor in the absence of pretransfusion compatibility testing was 6%. CONCLUSION The frequency of DEA 1.1 expression in dogs in Portugal is high, and there is a potential risk of sensitization following transfusion with blood that is not typed or cross-matched. Breed-related frequencies may help predict DEA 1.1-positivity, but the best practice is to type and cross-match blood before transfusion.

Interleukin-6 gene −174G>C and −636G>C promoter polymorphisms and prostate cancer risk

Prostate cancer (PCa) is one of the most commonly diagnosed internal malignancies affecting men. Due to the important roles of IL-6 in different physiological and pathophysiological processes, IL-6 polymorphisms may modulate PCa risk. IL-6 −174 G>C (rs 1800795, also designated −236 G>C) and −636 G>C (rs 1800796, also designated −572 G>C) promoter polymorphisms have been implicated in PCa susceptibility, albeit still controversial. A literature search using PubMed and Highwire databases was conducted, resulting in eight case–control studies concerning the IL-6 −174 G>C polymorphism (11,613 PCa cases and 13,992 controls) and four case–control publications regarding the IL-6 −636 G>C polymorphism (1,941 PCa cases and 3,357 controls). In order to derive a more precise estimation, a meta-analysis based upon these selected case–control studies was performed. There was no significant association between IL-6 −174 G>C polymorphism and PCa increased risk. Nevertheless, the presence of allele C and the CC genotype were statistically significantly associated with decreased PCa risk in the overall analysis for IL-6 −636 G>C polymorphism. Additional studies in larger samples and analyses of functional repercussions of these SNPs in prostate tumor cells are necessary to validate these findings.

Matrix metalloproteinase-9 expression in mammary gland tumors in dogs and its relationship with prognostic factors and patient outcome

OBJECTIVE To immunohistochemically evaluate matrix metalloproteinase (MMP)-9 expression in benign and malignant mammary gland tumors (MMTs) in dogs and relate expression to prognostic factors and patient outcome. ANIMALS 118 female dogs with naturally occurring mammary gland tumors and 8 dogs without mammary gland tumors. PROCEDURES 24 benign mammary gland tumors and 94 MMTs (1/affected dog) were obtained during surgical treatment; control mammary gland tissue samples were collected from unaffected dogs after euthanasia for reasons unrelated to the study. Tumors were evaluated for proliferation, invasive growth, histologic grade, and metastatic capacity; expression of MMP-9 was determined immunohistochemically, and its relationship with clinical and histologic findings was investigated. For dogs with MMTs, follow-up continued for 2 years; data were used to compute overall survival time and disease-free interval and construct survival curves. RESULTS MMTs had significantly higher MMP-9 expression in stromal cells and in neo-plastic cells than did the benign neoplasms. Stromal MMP-9 expression was also higher in highly proliferative tumors and in tumors with invasive growth, high histologic grade, and metastatic capacity. Furthermore, tumors from patients with shorter overall survival times and disease-free intervals had higher expression of MMP-9 in stromal cells. CONCLUSIONS AND CLINICAL RELEVANCE In dogs with MMTs, level of MMP-9 expression by stromal cells was related to factors of poor prognosis and shorter overall survival times and disease-free intervals. These results suggested that MMP-9 produced by tumor-adjacent stromal cells contributed to MMT progression in female dogs and that assessment of MMP-9 expression may be a valuable prognostic factor.