Immunohistochemical and molecular analysis of caveolin-1 expression in canine mammary tumors.

Caveolin-1 (Cav-1) is a structural protein present in invaginations of the cell membrane. In human breast cancer, the cav-1 gene is believed to be a tumor suppressor gene associated with inhibition of tumor metastasis. However, little is known about its expression, regulation and function in canine mammary tumors. Expression levels of cav-1 were investigated using real-time PCR and immunohistochemical detection with an anti-human Cav-1 antibody. Gene expression stability of different samples was analyzed using the geNorm software. Mammary tumors from 51 female dogs were compared to normal mammary tissue from 10 female dogs. Malignant mammary cells showed a loss of Cav-1 expression by quantitative RT-PCR and weak Cav-1 staining by immunohistochemistry compared to normal mammary gland tissue. There was a significant relationship between outcome and immunostaining as well as with tumor size, indicating that caveolin subexpression has a positive predictive value and is related to higher survival and smaller tumor size. Our findings indicate that Cav-1 is a potential prognostic marker for canine mammary tumors.

Interleukin-8 expression associated with canine mammary tumors.

The use of prognostic markers for mammary cancer is important for routine diagnosis and research. Interleukin-8 (IL-8) is a chemotactic cytokine, produced by several cell types in response to inflammation. The expression, regulation and function of IL-8 in dogs are little known. Recent studies have associated angiogenesis and inflammatory processes with tumor malignancy. We investigated a possible correlation between IL-8 expression and mammary tumor prognosis in female dogs. IL-8 expression was measured in 50 dogs with mammary neoplasia by immunohistochemistry and real-time PCR. Immunohistochemical staining was done with anti-IL-8 antibodies and PCR amplifications were performed in a 7500 Fast Real-Time PCR system. Gene expression stability was analyzed by the geNorm software. Quantitative real-time PCR showed that IL-8 expression decreased in malignant mammary cells compared to normal mammary tissue, while weak immunostaining was associated with a diagnosis of carcinoma. Complementing earlier studies on IL-8 expression in several types of cancer, including mammary cancer, we conclude that IL-8 has potential for use as a prognostic marker for canine mammary neoplasia.

Expressão imunoistoquímica e molecular da laminina-332 cadeia gama-2 em tumores mamários de cadelas / Immunohistochemical and molecular expression of laminin-332 gamma-2 chain in canine mammary tumors

Forty-eight cases of canine mammary cancer were investigated to evaluate the immunohistochemical distribution of the γ2 chain of laminin-332. Tumor cells were compared to a pool of normal mammary tissues using quantitative RT-PCR. The western blot was performed in eight tumor samples as complementary test to evaluate protein integrity. Immunohistochemistry experiments showed negative, focal, and weak expression of laminin-332 γ2 in tumors with the worst prognosis. Quantitative PCR revealed downregulation of the gene in 27 (56.2 percent) of the animals. Out of the 16 dogs with γ2 chain overexpression, seven were still alive. The western blot results showed bands generation of 36, 50, and 98kDa, suggesting degradation of laminin-332 γ2 in malignant tumors. The results suggest that, in the future, low expression and/or degradation of laminin-332 γ2 chain in canine mammary tumors may be used as an indicator of malignant potential. However, further studies are necessary to corroborate these results.

Para avaliar a expressão imunoistoquímica da cadeia γ 2 da laminina-332, foram investigados 48 casos de câncer mamário canino. Comparou-se, por RT-PCR, a expressão gênica nas células tumorais com um pool de tecido mamário. Como teste complementar, em oito amostras tumorais, realizou-se western blot para avaliar a integridade da proteína laminina-332 γ 2. A imunoistoquímica demonstrou expressão negativa, focal e fraca da laminina-332 γ 2 nos tumores com pior prognóstico. A RT-PCR quantitativa revelou a baixa expressão do gene em 27 (56,2 por cento) dos animais. Das 16 cadelas com superexpressão da cadeia γ 2, sete ainda estavam vivas no final do estudo. O resultado do western blot mostrou bandas de 36, 50 e 98kDa, sugerindo uma degradação da laminina-332 γ 2 em tumores malignos. Os resultados sugerem que, no futuro, a baixa expressão e/ou degradação da laminina-332 γ 2 nos tumores mamários caninos podem ser utilizadas como indicadores de potencial maligno. No entanto, mais estudos são necessários para confirmar estes resultados.