Heat Shock Proteins Expression in Canine Intracutaneous Cornifying Epithelioma and Squamous Cell Carcinoma

Heat shock proteins (HSPs) are strongly implicated in the control of cell growth, differentiation andbiological behaviour of many human cutaneous neoplasms. To our knowledge, no data have been published inthe veterinary literature concerning either normal or neoplastic skin. In this study, the immunohistochemicalexpression of Hsp27, Hsp72 and Hsp73 was evaluated in normal canine skin, 14 intracutaneous cornifying epitheliomas(ICE), 10 well-differentiated and 5 moderately differentiated squamous cell carcinomas (SCC). Expressionwas correlated with the histological degree of keratinocyte differentiation and proliferation, and investigatedas to its usefulness in the differential diagnosis of these canine tumours. In normal epidermis, Hsp27 exhibitedcytoplasmic labelling in the spinous and granular layers, whereas in neoplastic tissues it was detected particularlyin those areas showing squamous differentiation. Hsp72 immunoreactivity was more intense in ICE and welldifferentiatedSCC than in normal skin; however, reduced immunolabelling was observed in moderately differentiatedSCC. Unlike Hsp72, Hsp73 showed less intense labelling in ICE and well-differentiated SCC than in normalepithelium and an increased positivity in moderately differentiated SCC. These results indicate that HSPimmunoreactivity differs between normal and neoplastic canine skin. Hsp27 expression seems to correlatedirectly with cellular differentiation; by contrast, the involvement of Hsp72/73 in proliferation and differentiationof tumour cells remains controversial. The pattern and intensity of immunolabelling of each investigated HSPdid not show, however, significant differences between ICE and SCC; therefore, they do not seem to be useful inthe differential diagnosis of these two canine tumours.[...]