ucn-1028-c and Neoplasms

Acyl hydrazone is an important functional group for the discovery of bioactive small molecules. This functional group is also recognized as a pan assay interference structure. In this study, a new small-molecule inhibitor for the β-catenin/Tcf protein-protein interaction (PPI), ZINC02092166, was identified through AlphaScreen and FP assays. This compound contains an acyl hydrazone group and exhibits higher inhibitory activities in cell-based assays than biochemical assays. Inhibitor optimization resulted in chemically stable derivatives that disrupt the β-catenin/Tcf PPI. The binding mode of new inhibitors was characterized by site-directed mutagenesis and structure-activity relationship studies. This series of inhibitors with a new scaffold exhibits dual selectivity for β-catenin/Tcf over β-catenin/cadherin and β-catenin/APC PPIs. One derivative of this series suppresses canonical Wnt signaling, downregulates the expression of Wnt target genes, and inhibits the growth of cancer cells. This compound represents a solid starting point for the development of potent and selective β-catenin/Tcf inhibitors.

Topics: Antineoplastic Agents; beta Catenin; Blotting, Western; Cell Proliferation; Drug Discovery; Enzyme-Linked Immunosorbent Assay; HEK293 Cells; Humans; Hydrazones; Immunoprecipitation; Models, Molecular; Molecular Structure; Neoplasms; Protein Binding; Protein Interaction Maps; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Small Molecule Libraries; Structure-Activity Relationship; TCF Transcription Factors; Tumor Cells, Cultured; Wnt Signaling Pathway

Lamin B1, a major component of the nuclear lamina, anchors the nucleus to the cytoskeletal cage, and controls nuclear orientation, chromosome positioning and, alongside several enzymes, fundamental nuclear functions. Exposing polyomavirus-transformed rat pyF111 fibroblasts and human cervical carcinoma (HCC) C4-I cells for 30 min to photoexcited perylenequinone calphostin C, i.e. Cal C(phiE), an established reactive oxygen species (ROS)-generator and protein kinase C (PKC) inhibitor, caused the cells to selectively oxidize and then totally destroy their nuclear lamin B1 by only 60 min after starting the treatment, i.e. when apoptotic caspases' activities had not yet increased. However, while the oxidized lamin B1 was being destroyed, lamins A/C, the lamin A-associated nuclear envelope protein emerin, and the nucleoplasmic protein cyclin E were neither oxidized nor destroyed. The oxidized lamin B was ubiquitinated and demolished in the proteasome probably by an enhanced peptidyl-glutaminase-like activity. Hence, the Cal C(phiE)-induced rapid and selective lamin B1 oxidation and proteasomal destruction ahead of the activation of apoptotic caspases was by itself a most severe molecular lesion impairing vital nuclear functions. Conversely, Cal C directly added to the cells kept in the dark damaged neither nuclear lamin B1 nor cell viability. Thus, our findings reveal a novel cell-damaging mechanism of a photodynamic tumor therapeutic agent.

Topics: Animals; Antibiotics, Antineoplastic; Apoptosis; Cell Line, Transformed; Cell Line, Tumor; Humans; Immunohistochemistry; Lamin Type B; Naphthalenes; Neoplasms; Nuclear Envelope; Oxidative Stress; Photochemotherapy; Proteasome Endopeptidase Complex; Rats; Ubiquitination