Expression and activation of platelet-derived growth factor 13 receptor, mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK) and extracellular signal-regulated kinase (ERK) in canine mammary' tumours

Canine mammary tumours are frequent neoplasms mostly affecting intact female dogs, for which no 100% efficient therapy is available. Platelet derived growth factor beta receptor (PDGF beta R) is a tyrosine kinase receptor (TKR) with a potential role in human breast cancer and a series of canine tumours. In this study we demonstrated, for the first time, expression of PDGF beta R and its downstream transduction molecules, mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK) and extracellular signal-regulated kinase (ERIC), as well as their activated forms in canine mammary tumours by both biochemical analysis and immunohistochemistry. PDGF beta R was expressed and hyperphosphorylated in the majority of tumour samples and tumour derived cell lines. Additionally, both MEK and ERK were expressed and activated in cell lines as well as biopsies. TKR inhibitors (TKRi) are currently under investigation as possible therapy in human breast and several canine tumours, thus our in vivo and in vitro findings pave the way for future studies aimed at establishing a potential therapeutic employment of TKRi for the treatment of canine mammary cancer.(C) 2016 Elsevier Ltd. All rights reserved.