Expression of p53, bcl-2 Proteins and Estrogen Receptors in Human Breast Cancer

ABSTRACT

In 56 breast cancer tissues (infiltrating ductal carcinoma) with a clinical follow-up period of more than 5 years, positivity of estrogen receptor(ER) by enzyme immunoassay and expressions of bcl-2 and p53 oncoproteins by immunohistochemistry were evaluated. The purposes of this study were to determine prevalence of bcl-2 and p53 in breast cancer, the interrelationship between expression of the proteins and estrogen receptor, correlation between histologic grade and the expression of the tumor-related oncogenes, and to explore the biologic bahavior of breast cancer (lymph node metastasis, recurrence rate, and survival) via expression of bcl-2 and p53. Twelve of 56 (21.4%) carcinomas were bcl-2 positive, and seventeen (30.4%) were p53- positive. Eleven of 12 bcl-2 positive tumors (91.7%) were ER-positive, and bcl-2 expression was significantly associated with ER-positivity(P=0.043). Seven of 36 ER-positive tumors (12.5%) were p53 positive, and p53 expression was inversely associated with ER-positivity(P=0.006) significantly. The bcl-2 protein expression showed a significant relationship to low histologic grade of tumor (P=0.0002), and an almost significant relationship to lower recurrence rate (P=0.09). The p53 protein expression showed a significant relationship to high histologic grade of tumor (P=0.002) and an almost significant relationship to lymph node metastasis (P=0.09). Also an almost inverse relationship between bcl-2 and p53 was demonstrated (P=0.057). The bcl-2 expression had a tendency to be associated with longer patient survival(P= 0.09), but p53 immunoreaction was found not to be associated with shorter patient survival(P=0.16). These results provide further evidence that higher incidence of bcl-2 expression is correlated with higher incidence of ER and lower grade of tumor, while p53 expression is correlated with lower incidence of ER and higher grade of tumor. In conclusion, although the biologic function of bcl-2 protein is not yet well understood in breast cancer, our results suggest that bcl-2 and p53 oncoproteins might play significant roles in estrogen receptor and development of breast cancer. But their prognostic significance could not be determined; our results are 'not significant' but 'almost significant'. Thus, contribution of bcl-2 and p53 immunohistochemical phenotyping of breast cancer with ER to the clinical management need verification in larger series.