Fig. 1.

The naturally occurring AR splice variant AR3 (AR-V7) is up-regulated in castration-resistant VCaP tumor xenografts. A, VCaP cells stably expressing GFP were inoculated into the hind flanks of SCID mice. When tumors reached a volume of approximately 300 mm³, three tumors were harvested and represent androgen-dependent tumors. The remaining mice were castrated, and the castration-resistant tumors were harvested when tumor volumes reached 1000 mm³ (approximately 6–9 wk after castration). Tumor lysates were immunoblotted for AR (N-terminal AR, AR-N20), AR3, and actin. The 22Rv1 and VCaP cell lines served as positive and negative controls, respectively. B, VCaP cells stably expressing GFP or Vav3-FLAG were injected into mice as described in A. AR3 levels in five GFP and six Vav3-FLAG VCaP tumors were analyzed via densitometry. Data (± sem) are graphed as AR3 levels normalized to actin. *, P < 0.05.