Immunohistochemical analysis of advanced human breast carcinomas reveals downregulation of protein kinase Cα

Forty-six advanced-stage human breast carcinoma specimens were evaluated by immunohistochemistry for PKCalpha. expression and compared with 25 samples of normal adjacent breast tissue. For normal tissue, the median staining of ductal epithelia was of moderate intensity. No staining was observed for 67% of tumor specimens, and only 4% showed intensities greater than the median observed in normal tissue. Faint to moderate PKCa staining was observed in the stroma, inflammatory cells, and fibroblasts of tumors but was absent in normal tissue. These findings demonstrate that downregulation of PKCalpha protein occurs in epithelial cells of advanced breast tumors (p<0.001).