Effects of PSP on CSC properties.

<p>A) Spheroid formation assay was performed with PC-3 and Du145 cells. Two hundred of cells were seeded onto polyHEMA pre-coated plates and treated with either 500 µg/mL of PSP or vehicle for 14 days. The number of prostaspheres formed was counted, and the result was presented as the mean ± s.d. Note that γ-T3 treatment efficiently suppresses the spheroid formation ability of PC-3 cells. Image of the prostaspheres was captured under microscope. Note that no prostaspheres can be found in cells treated with 500 µg/mL of PSP. (B) PSP inhibited the formation of secondary prostaspheres. Primary prostaspheres were dissociated and re-seeded into polyHEMA pre-coated plate. PSP was added 24 hr after the plating. Note that prostasphere formation was inhibited by more than 70% and 90% in the presence of 250 µg/mL and 500 µg/mL of PSP respectively. * <i>P</i><0.001, ** <i>P</i><0.0001, <i>t</i> test.