P53 and Ki67 protein expression in ocular squamous cell carcinomas of dairy cattle

Role of the protein overexpression is very important in the pathogenesis, diagnosis and prognosis of neoplasia. Cases of overexpression of p53 and Ki67 proteins were investigated in 19 ocular squamous cell carcinomas (OSCC) in dairy cows. Microscopically, insix cases the tumors were carcinoma in situ (noninvasive carcinoma, G0), and in the remaining 13 cases the tumors were invasive carcinoma. The distribution of invasive carcinoma was as follows: G1, 1 (7.6%); G2, 1 (7.6%); G3, 3 (23.0%); G4, 8 (61.8%). Of the 19 tumors, 18 were immunoreactive for p53 (++), and 14 showed Ki67 expression (++). A significant positive correlation was found between the percentage of p53 stained nuclei and the degree of differentiation. The Ki67 index showed a significant negative correlation with the histological pattern, where the greatest proliferation was found in the most poorly differentiated OSCC. As in human squamous cell carcinoma(SCC), p53 overexpression is frequent in bovine OSCC, providing support for a possible role of the protein in the pathogenesis of this neoplasm.