Co-localization of PTEN and E-cadherin in canine mammary hyperplasias and benign and malignant mammary tumors

•Evaluation of PTEN and E-cadherin co-expression in hyperplastic and neoplastic mammary tissues•Positive co-localization of PTEN and E-cadherin in hyperplasias and benign tumors•Loss of expression of both markers from benign to malignant neoplasia•PTEN +/E-cad-mammary carcinomas were associated with a poorer prognosis.•The loss of PTEN expression may lead to an E-cadherin down-regulation.

Fifty-four canine mammary lesions (15 hyperplasias, 7 adenomas and 32 carcinomas) were submitted to immunohistochemical analysis for the evaluation of PTEN and E-cadherin co-expression. Subjects bearing mammary carcinomas were also submitted to a 2-year follow-up study to compare immunohistochemical results with overall survival. All the hyperplastic samples stained positive for both markers, 100% of adenomas were positive for PTEN and 86% for E-cadherin, and 69% and 34% of carcinomas were positive for PTEN and E-cadherin, respectively. Statistical analysis showed a positive correlation between these two proteins both considering all (p < 0.01) or malignant tumors (p < 0.05). The female dogs bearing tumors positively-stained for both markers had a longer overall survival (p < 0.05) and absence of lymphatics invasion (p < 0.05). Simultaneous double immunofluorescence confirmed the co-localization of the two proteins in neoplastic cells. Results reported in this study confirm the tumor suppressor effect of these two molecules.