Expression of the Ca2+-selective cation channel TRPV6 in human prostate cancer:: a novel prognostic marker for tumor progression

Members of the TRP superfamily of cation channels have homeostatic and regulatory functions in cells and changes in their expression may contribute to malignant growth. Previously, we have demonstrated that the gene of the Ca2+-selective cation channel CaT-L or TRPV6 is not expressed in benign prostate tissues including benign prostate hyperplasia, but is upregulated in prostate cancer. Here, we report on the differential expression of TRPV6 mRNA in prostate tissue obtained from 140 patients with prostate cancer. Using in situ hybridization, TRPV6 transcripts were undetectable in benign prostate tissue, high-grade prostatic intraepithelial neoplasia (n = 57), incidental adenocarcinoma and all tumors less than 2.3 cubic centimeter (cc). In prostatectomy specimens from 97 clinically organ-confined tumors, TRPV6 expression correlated significantly with the Gleason score (P = 0.032), pathological stage (P<0.001) and extraprostatic extension (P = 0.025). Lymph node metastasis (n = 17) and androgen-insensitive tumors (n = 27) revealed TRPV6 expression in 63 and 67% of cases, respectively. The latter, however, revealed markedly and significantly decreased levels when compared with untreated tumors (P = 0.044). In summary, the data demonstrate that TRPV6 expression is associated with prostate cancer progression. Accordingly, TRPV6 represents a prognostic marker and, as a plasma membrane Ca2+ channel, a promising target for new therapeutic strategies to treat advanced prostate cancer.