Direct effects of chemotherapeutic agents on rat prostate tumor clonogenic cells.

A semisolid agar assay to determine the number of colony forming cells in monodispersed cell suspensions of the rat prostate hormone independent tumor variant R3327-Mat Lu was established. Using this technique the effects of several chemotherapeutic agents upon the clonogenic potential of the tumor cells were investigated. Adriamycin and cisplatinum proved to be effective in reducing the number of colonies formed, in a dose dependent manner. The combined, sequential incubation with adriamycin and cisplatinum did not have a synergistic effect. Cyclophosphamide. Hydroxyurea, 5-fluorouracil and methotrexate were not effective in the reduction of the number of colonies in vitro at concentrations as high as 500 micrograms/ml. Interestingly treatment with these agents increased the number of colonies formed, compared to control.