Cadmium Concentration and Metallothionein Expression in Prostate Cancer and Benign Prostatic Hyperplasia of Humans

Background/Purpose: Cadmium (Cd) causes various genitourinary disorders and is a carcinogen for prostate cancer. Metallothionein (MT) is a protein that detoxifies heavy metals. We evaluated changes in Cd concentration and MT expression in human prostate cancer (CaP) and benign prostatic hyperplasia (BPH). Our goal was to clarify the relationship between Cd concentration and MT expression in prostatic diseases. Methods: The experimental group consisted of 18 patients who underwent radical prostatectomy for CaP. The control group consisted of 35 patients who underwent transurethral resection of the prostate for BPH, Tissue samples were acquired from the gross tumor site and from resected chips. We determined Cd concentration by atomic absorption, MT expression by immunoblotting, and immunohistochemical staining. The significance of between-group differences for these outcomes was analyzed using Student's t tests. Results: There was no statistically significant difference in Cd concentration between the CaP and BPH groups. Immunoblots from both groups revealed a single band. The relative intensity of the MT band was 0.58 +/- 0.09 in the BPH group and 0.17 +/- 0.03 in the CaP group. MT expression in patients with BPH was 3.4-fold higher than in those with CaP. Conclusion: MT may bind heavy metals and protect patients from CaP. Additional studies are needed to reveal the factors that influence the expression of MT in prostate epithelial cells, and to analyze the free and compound forms of Cd at the same time. [J Formos Med Assoc 2009;108(7):554-559]