Papel de las células mioepiteliales en el carcinoma de mama canino

Abstract

Mammary tumours are the most common neoplasms in female dogs and the participation of the myoepithelial (ME) cells in its constitution is very high. Some immunohistochemical and in vitro studies of human breast cancer suggest that these cells have tumour suppressor functions. In these studies, the role of ME cells in the stromal invasion of canine mammary carcinoma and the isolation, purification and culture methods of canine ME cells have been analyzed and standardized, respectively. The integrity of the ME cell layer around groups of atypical epithelial cells was evaluated in tissue samples of benign and malignant tumours and its correlation with the histological grade of malignancy and proliferation index of the lesions were analyzed. Results showed that the level of expression of calponin, the marker used to identify this layer, was similar in benign and malignant tumours of histological grades 1 and 2. These findings indicated that ME cells were not good marker of invasion to diagnose in situ carcinoma of the canine mammary gland. On the contrary, they suggest a potential protective on the progression of the disease. Isolation and purification of ME cells requires the use of non-available specific surface markers of ME cells of the canine mammary gland. The expression of CD10 antigen and Thy1 (thymocyte differentiation antigen), both considered to be sensitive and specific surface markers of human breast ME cells, were analyzed by immunohistochemistry in ME cell and epithelial cell immunophenotypes of the normal and neoplastic canine mammary gland. CD10, as the majority of canine ME cell marker, proved to be sensitive but not specific, whereas Thy1 marked ME cells exclusively. Finally, ME cells from normal and neoplastic canine mammary gland were isolated and purified using an immunomagnetic method (MACS) and Thy1 marker. The results of this study showed the possibility of isolation and culture of canine ME cells for first time in literature opening this way the possibility of studying in vitro their role in the development of canine mammary tumours with novel and powerful techniques.