icg-001 and Colonic-Neoplasms

The importance of upregulated Wnt signaling in colorectal cancers led to efforts to develop inhibitors that target β-catenin in this pathway. We now report that several "Wnt inhibitors" that allegedly target β-catenin actually function as mitochondrial proton uncouplers that independently activate AMPK and concomitantly inhibit Wnt signaling. As expected for a process in which mitochondrial uncoupling diminishes ATP production, a mitochondrial proton uncoupler, FCCP, and a glucose metabolic inhibitor, 2-DG, activated AMPK and inhibited Wnt signaling. Also consistent with these findings, a well-known "Wnt inhibitor", FH535, functioned as a proton uncoupler, and in support of this finding, the

Topics: AMP-Activated Protein Kinases; Animals; beta Catenin; Brain; Colonic Neoplasms; Energy Metabolism; Enzyme Activation; Enzyme Activators; Gene Expression Regulation, Neoplastic; Humans; Hydrocarbons, Fluorinated; Mitochondria; Oxygen Consumption; Sulfonamides; Tumor Cells, Cultured; Urea; Wnt Proteins

Targeting of human cancer stem cells (CSCs) requires the identification of vulnerabilities unique to CSCs versus healthy resident stem cells (SCs). Unfortunately, dysregulated pathways that support transformed CSCs, such as Wnt/β-catenin signaling, are also critical regulators of healthy SCs. Using the ICG-001 and CWP family of small molecules, we reveal Sam68 as a previously unappreciated modulator of Wnt/β-catenin signaling within CSCs. Disruption of CBP-β-catenin interaction via ICG-001/CWP induces the formation of a Sam68-CBP complex in CSCs that alters Wnt signaling toward apoptosis and differentiation induction. Our study identifies Sam68 as a regulator of human CSC vulnerability.

Topics: Adaptor Proteins, Signal Transducing; Adult; Aged; Animals; Apoptosis; Azabicyclo Compounds; beta Catenin; Breast Neoplasms; Bridged Bicyclo Compounds, Heterocyclic; Cell Differentiation; Cells, Cultured; Colonic Neoplasms; DNA-Binding Proteins; Female; Humans; Leukemia, Myeloid, Acute; Male; Mice; Mice, Inbred NOD; Middle Aged; Neoplastic Stem Cells; Organophosphates; Peptide Fragments; Proto-Oncogene Proteins c-myc; Pyrimidinones; RNA Interference; RNA-Binding Proteins; Sialoglycoproteins; Sumoylation; Transcriptome; Wnt Signaling Pathway

Inherited and somatic mutations in the adenomatous polyposis coli occur in most colon cancers, leading to activation of beta-catenin-responsive genes. To identify small molecule antagonists of this pathway, we challenged transformed colorectal cells with a secondary structure-templated chemical library, looking for compounds that inhibit a beta-catenin-responsive reporter. We identified ICG-001, a small molecule that down-regulates beta-catenin/T cell factor signaling by specifically binding to cyclic AMP response element-binding protein. ICG-001 selectively induces apoptosis in transformed cells but not in normal colon cells, reduces in vitro growth of colon carcinoma cells, and is efficacious in the Min mouse and nude mouse xenograft models of colon cancer.

Topics: Adenomatous Polyposis Coli; Animals; Antineoplastic Agents; Apoptosis; beta Catenin; Bridged Bicyclo Compounds, Heterocyclic; Cell Line; Colon; Colonic Neoplasms; Cyclic AMP Response Element-Binding Protein; Cyclin D1; Cytoskeletal Proteins; DNA-Binding Proteins; Epithelial Cells; Gene Expression Regulation; Inhibitor of Apoptosis Proteins; Lymphoid Enhancer-Binding Factor 1; Male; Mice; Mice, Inbred C57BL; Microtubule-Associated Proteins; Molecular Structure; Neoplasm Proteins; Pyrimidinones; Signal Transduction; Survivin; Trans-Activators; Transcription Factors; Transcription, Genetic