Reduced Kv1.3 potassium channel expression in human prostate cancer.

The presence of Kv1.3 voltage-gated potassium channels in rat and human prostate epithelial cells has been previously reported. We examined, by immunohistochemistry, Kv1.3 levels in 10 normal human prostate, 18 benign prostatic hyperplasia (BPH) and 147 primary human prostate cancer (Pca) specimens. We found high epithelial expression of Kv1.3 in all normal prostate, 16 BPH and 77 (52%) Pca specimens. Compared to normal, Kv1.3 levels were reduced in 1 (6%) BPH specimen and in 70 (48%) Pca specimens. We found a significant inverse correlation between Kv1.3 levels and tumor grade (r = -0.25, P = 0.003) as well as tumor stage (r = -0.27, P = 0.001). Study of an additional 30 primary Pca specimens showed that 15 (50%) had reduced Kv1.3 immunostaining compared to matched normal prostate tissue. Our data suggest that in Pca reduced Kv1.3 expression occurs frequently and may be associated with a poor outcome.