LA HEAT SHOCK PROTEIN 90 (HSP90) E' ASSOCIATA ALLA EVOLUZIONE IPERPLASTICA E NEOPLASTICA DELLA PROSTATA DEL CANE

HEAT SHOCK PROTEIN 90 (HSP90) IS ASSOCIATED WITH THE HYPERPLASTIC AND NEOPLASTIC EVOLUTION OF THE CANINE PROSTATE The dog represents an important animal model for studying the human prostatic diseases, being exposed to the same environmental conditions and being one of the few species in which prostate cancer spontaneously occurs. In this study, we have evaluated the expression of HSP90 – marker of neoplastic transformation, regulating the androgen receptor activity – in canine Benign Prostatic Hyperplasia (BPH) and Prostatic Carcinoma (PCA). IHC has been performed on 24 samples (2 normal tissues, 17 BPH, 5 PCA). HSP90 expression was mild/moderate, mainly perinuclear, in normal tissues, with a progressive increase of staining intensity and diffuse cytoplasmic and nuclear immunoreactivity in BPH, PCA and metastatic lesions. By means of a semiquantitative analysis, grade 3 (≥ 10% - < 50% positive cells/total cells) was assigned to normal tissues, while 82.3% BPH cases and 100% PCA were scored as grade 4 (≥ 50% positive cells). Moreover, multifocal PIN (Prostatic Intraepithelial Neoplasia) and PIA (Proliferative Inflammatory Atrophy) with similar immunoreactivity to PCA were identified among hyperplastic and neoplastic lesions. In conclusion, the high HSP90 expression in our cases demonstrates that this protein could be involved in the sequential steps leading to prostate cancerogenesis and neoplastic evolution. In addition, veterinary pathologists should pay special attention to recognize specific preneoplastic lesions (PIA, PIN) – underestimated in dog – also in those tissues that look benign