The androgen-signaling pathway plays an important role in the development and hormonal progression of prostate cancer to the castrate-resistant stage (also called androgen-independent or hormone refractory). The Wnt pathway and β-catenin contribute to prostate biology and pathology. Here application of Affymetrix GeneChip analysis revealed the genomic similarity of the LNCaP hollow fiber model to clinical samples and identified genes with differential expression during hormonal progression. The fiber model samples clustered according to the expression profile of androgen-regulated genes to provide genomic evidence for the reactivation of the AR signaling pathway in castrate-resistant prostate cancer. Pathway-based characterization of gene expression identified activation of the Wnt pathway. Together with the increased expression of AR and β-catenin, there was increased nuclear colocalization and interaction of endogenous AR and β-catenin in castrate-resistant prostate cancer from castrated mice. Surprisingly, no interaction or colocalization of AR and β-catenin could be detected in xenografts from noncastrated mice. These studies provide the first in vivo evidence to support aberrant activation of the AR through the Wnt/β-catenin signaling pathway during progression of prostate cancer to the terminal castrate-resistant stage. [Cancer Res 2008;68(23):9918–27]