Figure 1

Tumorigenicity of hTERT-immortalized cells under non-adherent culture conditions and formation of xenograft tumors. A) hTERT-immortalized epithelial cells lines (RC-58T/hTERT/SA#4-D, RC-92a/hTERT, SCID5083-6, RC-193a/hTERT, and SCID5080A-1, RC-58T/h/SA#4-k, RC-165N/h, PrEC-6) from prostate cancer or non-cancer patients form spheroid structures (called here prostaspheres). The images were taken at 100 × magnification. B) Prostaspheres were serially passaged under non-adherent culture conditions. RC-58T/hTERT/SA#4-D was passaged 10 times without showing a decline in sphere forming capability. The passaging capacities of prostaspheres from RC-92a/hTERT, SCID5083-6, RC-193a/hTERT, and SCID5080A-1 were tested for three generations (n = 6; error bars indicate the standard deviation of sphere-forming efficiency for each type of cell line). C) Xenograft tumor generation with RC193a/hTERT, SCID5080A-1, RC-58T/hTERT/SA#4-D cells cultured as monolayers required large numbers of injected cells. The error bars indicate the lower and upper limits of the confidence interval based on the limiting dilution calculation.