Introduction

Cell lines derived from tumours and tissues have been historically important instruments for understanding neoplastic behaviour. In CMT, previous studies have shown that both HER2 amplification and overexpression are detectable among different histological types in dogs and humans. Human breast cancer has been described to positively express HER-2; it is used as a prognostic marker on its own or in association with other proteins, such as p53.

Objectives

Expression of p53 and human epidermal growth receptor 2 (HER2) proteins were investigated in benign mixed tumour (BMT), complex carcinoma (CC), simple carcinoma (SC), and spindle cell carcinoma (SCC) and cell cultures derived from them.

Methods

Fragments and individualised cells were cultured together under no hormonal/growth factor stimuli. Immunohistochemistry and immunocytochemistry were performed, and the results were compared according to World Health Organization. Vimentin and cytokeratin antigens were quantified to characterise CMT and cell cultures as epithelial and/or mesenchymal in phenotype. The p53 and HER2 proteins were detected by immunohistochemistry in tumours.

Results

Seventeen CMT were classified and divided into BMT, CC, SC, and SCC. Differences between vimentin/cytokeratin phenotypes were observed in CC and SCC, typical for canine carcinoma. CMT-derived cell culture revealed epithelial-mesenchymal transition in all CMT samples. Expression of p53 was low in BMT and CC, medium in SC, and not detectable among SCC. Different results were observed in CMT-derived cultured cells; p53-positive cells were increased under in vitro conditions. HER2 protein expression was low in BMT, CC, and SCC and MCT-derived cells were considered HER2-positive in all MCT types.

Conclusions

CMT cell culture can be used as a biological model to understand how cancer cells behave differently and/or similarly under in vivo and in vitro conditions and can be considered an important issue in cancer cell proliferation.