Cell proliferation, nuclear ploidy, and EGFr and HER2/neu tyrosine kinase oncoproteins in infiltrating ductal breast carcinoma.

The purpose of this work was to study if the variations in the nuclear DNA content and the expression of EGFr and HER2/neu transmembrane oncoproteins were related and if this influences the rate of cell proliferation modifying, in each case, the potential aggressivity of the neoplasia. Thirty-four ductal breast carcinoma tissue samples of tumors of up to 2 cm in diameter were analyzed by flow cytometry. HER2/neu and EGFr were measured by immunohistochemical methods. Twenty cases were diploid (DNA index of 1) and 14 cases were aneuploid (DNA index other than 1). The expression of EGFr and HER2/neu was significantly higher in aneuploid tumors compared with diploid tumors. The cell proliferation rate was significantly higher in tumors with an aneuploid pattern. The expression of EGFr was associated with a higher rate of cell proliferation. The higher expression of EGFr and HER 2/neu oncoproteins in aneuploid tumors suggests that the increased proliferative activity of aneuploid carcinomas is influenced by the activity of such oncoproteins, which favors a more aggressive biological behavior.