EGFR signaling blockage reduces the self-renewal activity of DU145 PCSCs.

<p>A) Western blot analysis of whole cell lysates following 24 hour treatment of DU145 spheres with DMSO (D) or increasing concentrations of AG1478 (0.1–20 µM concentration range), in the presence or absence of exogenous EGF (10 ng/ml; 10EGF). Sphere formation of EGF-free sphere cells was inhibited following treatment with EGFR inhibitors B) AG1478 or C) PD168393 at various doses in the presence (10EGF) or absence (-EGF) of exogenous EGF (10 ng/ml). Sphere cells were seeded at a density of 2×10³ cells/well (0.5 ml/well; three replicates per treatment). EGFR inhibitor (AG1478 or PD168393) or DMSO (mock) treatment was administered at the time of seeding. Spheres that formed were counted 12 days post-seeding. Sphere numbers are displayed as mean ± S.E.M. (the <i>p</i> values for the indicated comparisons were obtained by two-tailed independent Student’s <i>t</i>-test).