In vitro responses of human prostate tumour cell lines to a range of antitumour agents.

Four human prostate tumour continuous cell lines were employed for in vitro drug sensitivity testing of nine cytotoxic drugs, X-irradiation and two hormonal preparations. Responses were assessed by measuring cell survival as judged by colony formation in agarose. A marked heterogeneity of responses was noted to many of the agents studied, including X-irradiation. However, in terms of ID70 values for 24-h drug exposures, comparable responses in all the cell lines tested, with values falling within a 1.4- to 2.9-fold range, were noted with actinomycin D, adriamycin, m-AMSA, dibromodulcitol, 5-fluorouracil, hydroxyurea and ICRF-159. In contrast, mixed responses to cis-platinum and methotrexate were particularly marked, with ID70 values differing by factors of 3.8 and 7.5 respectively. In addition, when higher drug concentrations of m-AMSA, cis-platinum, dibromodulcitol and ICRF-159 were employed, significant deviations in the four survival curves became apparent. Continuous exposure to diethylstilboestrol and medroxyprogesterone acetate caused negligible cell kill. Due to these variable responses it was not possible to predict that any agent tested might have specific value in the treatment of prostate cancer. However, preliminary in vitro screening with such a panel of cell lines may complement in vivo studies with models of prostatic cancer and prove useful in investigations of mechanisms of drug resistance.