Immunohistochemical expression of protein p53 in neoplasms of the mammary gland in bitches

The aim of the study was to investigate the presence of protein p53 in correlation with other tumor traits: histological type, tumor grade and proliferative activity. Material for the investigation comprised mammary gland tumours collected from dogs, the patients of veterinary clinics, during surgical procedures, and archival samples. Alltogether 21 adenomas, 31 complex carcinomas, 35 simple carcinomas and 12 solid carcinomas were qualified for further investigation. No protein p53 expression was found in adenomas. Cancers show positive reaction in 32.5%. The highest percent of p53 positive neoplasms was observed in solid carcinomas and neoplasms with the highest degree of histological malignancy. The smallest number showing this expression was observed in adenomas and the highest was characteristic for solid carcinomas. Considering the tumour grading, it was found that an increase in neoplasm malignancy was positively correlated with the number of the cells showing the expression of protein p53. The differences were statistically significant. Statistically significant positive correlations were observed between the proliferative activity and protein p53 expression. Higher accumulation of protein p53 in more malignant neoplasms suggests that mutations of protein p53 can be responsible for higher proliferation in neoplasms with advanced progression of malignancy.