Serial analysis of chromatin occupancy identifies β-catenin target genes in colorectal carcinoma cells

Most instances of colorectal cancer are due to abnormalities in the Writ signaling pathway, resulting in nuclear accumulation of beta-catenin. beta-Catenin activates transcription of target genes primarily by associating with the T cell factor/lymphoid enhancerbinding factor (TCF/Lef) family of transcription factors. In this report, we use serial analysis of chromatin occupancy (SACO) to identify412 high-confidence beta-catenin targets in HCT116 colorectal carcinoma cells. Of these targets, 84% contained a consensus TCIF motif and were occupied by TCF4 in vivo. Examination of the flanking 5-bp residues in each consensus revealed motif-specific enrichment at neighboring sites. beta-Catenin binding was localized tothe 5'promoters, internal regions, and 3' IUTRs of protein-coding genes. Furthermore, 15 components of the canonical Writ pathway were identified as beta-catenin target genes, suggesting that feedforward and feedback mechanisms exist to modulate the Writ signal in colon cancer cells.