Valutazione dell'espressione di immunomarcatori nel tumore mammario felino

The use of companion animals as a cancer model for human oncology is leading to a better understanding of many cancerogenic aspects and to new therapeutic approaches. The high incidence, the histopathology, some tumorigenic aspects and the estrogen-independency, make of the feline mammary carcinoma a suitable model for the study of hormonal-independent breast cancers. In the present work, immunohistochemical evaluations of the expression of hormonal receptors, of the oncogene HER-2, of the oncosoppresor p53, of different cytoplasmic filaments (cytokeratins, vimentin, alpha-smooth muscle actin), of calponin, and of the proliferation marker Ki67 have been performed on feline mammary neoplasia, hyperplastic/dysplastic lesions, and normal mammary gland in 81 queens. The results are compared with the morphological aspects of the tumours and with the anamnestic and the follow-up data. Data obtained have allowed general considerations about neoplastic categories and more specific considerations about the expression of each marker. The cytoplasmic filaments have been investigated to better understand the histogenetic aspects of the feline mammary tumour and to eventually evaluate the presence of a "basal-like" group of cancers as described in women. The expression of basal cytokeratins (cytokeratin 5/6 and 14), that showed a positive correlation, and the high incidence of vimentin expression might suggest a pluripotent cell, a basal cell or a terminal duct as origin of the mammary tumours in the cat. In addition, the analysis of a-sma , calponin, and ck14 showed the presence of a myoepithelial component that was not always detected in routine histological sections, even when highly malignant, allowing in this way a better classification of the lesions. Regarding expression of specific markers, lower expression levels of HER-2 than what described within literature were observed, suggesting that this gene might not play a fundamental role in the feline mammary tumours development. Ki-67 presented a significant difference in expression between neoplastic and hyperplastic lesions, it positively correlated with grading, survival, and p53 expression, confirming its well-known role as indicator of the biological behavior of a neoplastic population. Finally, evidence of a large group of hormone-independent feline mammary tumours confirms a general more aggressive nature of these neoplasia in the feline species.