MUC1 expression in prostate carcinoma: Correlation with grade and stage

Mucins have been implicated in the biologic behavior and progression of several types of cancer. The aims of this study were to define the expression pattern of one particular mucin, MUC1, in benign and malignant human prostate tissue and to determine if MUC1 expression correlates with tumor grade and stage. Immunohistochemical staining utilizing an anti-MUC1 monoclonal antibody was performed on 4 fetal prostates, 4 specimens of benign prostatic hyperplasia (BPH), and 34 radical prostatectomy specimens. In human fetal and BPH specimens, there was an apical pattern of MUC1 expression, similar to that reported in other normal and benign tissues. Ninety-four percent of the prostate cancers were MUC1 positive. A high percentage of prostate cancer specimens (62%) demonstrated a diffuse, cytoplasmic staining pattern. There was a statistically significant correlation between diffuse MUC1 staining and Gleason pattern, with a diffuse/total staining percentage of 9% in Gleason 2, 64% in Gleason 3, 80% in Gleason 4, and 100% in Gleason 5. More diffuse staining was also seen in samples from patients with high pathologic stage: 21% in T₂, 75% in T₃, and 67% in N₁ disease. These data indicate that MUC1 expression is prevalent in prostate cancer and that diffuse cytoplasmic staining correlates with advanced Gleason pattern and advanced pathologic stage.