Ca2+ signaling is important for growth and survival of prostatic carcinoma (PCa) cells. Here we report that the gene for CAT1, a channel protein highly selective for Ca2+, is expressed at high levels in human PCa and in the LNCaP PCa cell line. CaT1 mRNA levels were elevated in PCa specimens in comparison to benign prostatic hyperplasia (BPH) specimens and positively correlated with Gleason grade in a PCa series. CaT1 mRNA was suppressed by androgen and was induced by a specific androgen receptor antagonist in LNCaP cells, suggesting that the gene is negatively regulated by androgen. These findings are the first to implicate a Ca2+ channel in PCa progression and suggest that CaT1 may be a novel target for therapy. © 2001 Academic Press.