Small-molecule antagonists of the oncogenic Tcf/β-catenin protein complex

Abstract

Key molecular lesions in colorectal and other cancers cause beta-catenin-dependent transactivation of T cell factor (Tcf)-dependent genes. Disruption of this signal represents an opportunity for rational cancer therapy. To identify compounds that inhibit association between Tcf4 and beta-catenin, we screened libraries of natural compounds in a high-throughput assay for immunoenzymatic detection of the protein-protein interaction. Selected compounds disrupt Tcf/beta-catenin complexes in several independent in vitro assays and potently antagonize cellular effects of beta-catenin-dependent activities, including reporter gene activation, c-myc or cyclin D1 expression, cell proliferation, and duplication of the Xenopus embryonic dorsal axis. These compounds thus meet predicted criteria for disrupting Tcf/beta-catenin complexes and define a general standard to establish mechanism-based activity of small molecule inhibitors of this pathogenic protein-protein interaction.

Evaluation of anti-Wnt/β-catenin signaling agents by pGL4-TOP transfected stable cells with a luciferase reporter system

“…The ELISAbased model limits the functional testing of the candidate drug to the β-catenin/TCF complex (10). However, the commercially available reporter plasmids for detecting Wnt/β-catenin signaling require transient transfection of the plasmid before drug screening.…”

Dysregulation of growth factor signaling in human hepatocellular carcinoma

“…Nonspecific inhibition (bystander effect) has been described for NSAIDs (aspirin and sulindac; Nath et al, 2003;Boon et al, 2004) and the tyrosine kinase inhibitor STI571 (Gleevec; Zhou et al, 2003). More specific approaches may employ small molecule antagonists that reduce b-catenin interaction to its binding partners (CREB (Emami et al, 2004) and TCF (Lepourcelet et al, 2004)) as well as antibodies against Wnts (e.g. Wnt-1; Mikami et al, 2005).…”

Nuclear co-localization and functional interaction of COX-2 and HIF-1α characterize bone metastasis of human breast carcinoma

“…Cells exposed to hypoxia alone were not starved. COX-2-reporter plasmid (-1432/+59)Luc or (-327/+59)Luc (S. Wilkinson, Vanderbilt University, Nashville, TN) was co-transfected with expression vectors for the dominant negative of ARNT (corresponding to mutated HIF-1 subunit), Jun (TAM67) or Ets-1 (EBHHB) [3,10], or treated with 50 g/ml SN50 (NF-kB inhibitor) or 10 M CGP049090 (TCF-inhibitor) [28,29]. As internal control, Renilla luciferase plasmid was co-transfected, and Firefly/Renilla luciferase activity ratios were calculated by the software.…”