Evidence of a novel biomarker, αs1-Casein, a milk protein, in benign prostate hyperplasia

Benign prostate hyperplasia (BPH) is a common disease in elderly men. Although it is a nonmalignant disease, it has a significant detrimental impact on the quality of life in patients with late-stage disease. Owing to the lack of specific markers, diagnosis of early-stage BPH has been proven unsuccessful. Recently, using two-dimensional electrophoresis, we identified a group of prostatic secretory proteins that are specifically produced by BPH cells (Xu et al., Electrophoresis 2003; 24: 1311). In this study, we investigated the potential diagnostic value of one of the secretory proteins, alpha s1-Casein, in BPH by inmmunohistological staining of normal, BPH and prostate cancer tissues. We found that 90% ( 20 out of 22) of BPH tissues showed moderate to strong alpha s1-Casein protein expression whereas none of the normal tissues ( 0 out of 10) and less than 10% of the prostate cancer tissues ( 3 out of 30) showed similar staining intensity. Our results suggest that alpha s1-Casein may be a potential biomarker for early identification of BPH patients.