Studies of rhodamine-123: Effect on rat prostate cancer and human prostate cancer cells in vitro

The effect of the lipophilic, cationic dye, Rhodamine‐123 (Rh‐123), on prostate cancer in rats, and on three tumor cell lines in vitro is reported here. The general toxicity of Rh‐123 in mice has been found to be minimal. Lobund‐Wistar (L‐W) rats with the autochthonous prostate cancer of Pollard were treated for six doses with Rh‐123 at a dose of 15 mg/kg subcutaneously every other day. Microscopic examination of the tumors revealed cellular and acinar destruction. The effectiveness of Rh‐123 as a cytotoxic agent was tested by clonogenic and viability assays in vitro with three human prostate cancer cell lines. Severe (60‐95%) growth inhibition was observed following Rh‐123 exposure for 2–5 days at doses as low as 1.6 μg/ml in all three prostate cancer cell lines.