Figure 6.

DU-145 uridine auxotrophs oppose the acute cytostatic effects of TFN. (A) DU-145 cells and their ρ^o clones were cultured for the indicated times inmediumcontaining 25 µMuridine and 50 µMTFN or Me₂SO (control). The cells were harvested and counted as described in Figure 2A. *P < .001 compared with the DU-145 control; **P < .01 or #P < .05 compared with the ρ^o control. (B) The percent S-phase cells in the indicated treatment populations was determined as described in Figure 2D. *P<.001 for the TFN-treated DU-145 cells compared with the respective control without or with uridine; **P < .01 for the TFN-treated ρ^o clones compared with the ρ^o control with uridine present. (C) The ρ^o clones were imaged 96 hours after treatment with 50 µM TFN, Me₂SO (control), or culture without uridine. The arrows in the DIC images point to the cell nucleus. Scale bars, 18 µm. The insets in the DIC images are representative PI (DNA) histograms for the treatments indicated. The percent S-phase cells in each treatment population was determined as described in panel (B).