Evaluation of apoptosis and correlation with heat shock protein (HSP) 27, 72 and 73 expression in canine Intracutaneous cornifying epitheliomas and squamous cell carcinomas

The events of cell stress and cell death are linked and some HSPs appear to play an important role in neoplastic process also inhibiting apoptotic pathways. This study was carried out on 9 Intracutaneous Cornifying Epitheliomas (ICE) and 13 Squamous CellCarcinomas (SCC). Immunohistochemical expression of Hsp27, 72 and 73 was determined using commercially antibodies, while apoptosis was evaluated through TUNEL method and immunohistochemical expression of total- and active-caspase-3. We found numerous TUNEL-positive tumour cells, prevalently in SCC, but only few active caspase3-positive cells, although there was a diffuse total-caspase-3 immunolabelling both in normal and neoplastic tissues. Hsp27 labelling was more intense in normal epidermis and in tumour areas showing squamous differentiation. Hsp72 and Hsp73 immunoreactivity were respectively more and less intense in ICE and SCC than in normal skin. We found a lack of correlation between TUNEL method and active-caspase-3 expression. Considering the limits of TUNEL assay in detecting only apoptotic cells, particularly in tumour tissues, we considered that detection of a scant number of active caspase3-positive cells and Hsp72 overexpression might be suggestive of an inhibition of apoptosis in these skin neoplasms, that might be important for oncogenesis and tumour growth.