ABSTRACT
TTK kinase was identified by in-house siRNA screen and pursued as a tractable, novel target for cancer treatment. A screening campaign and systematic optimization, supported by computer modeling led to an indazole core with key sulfamoylphenyl and acetamido moieties at positions 3 and 5, respectively, establishing a novel chemical class culminating in identification of 72 (CFI-400936). This potent inhibitor of TTK (IC50=3.6nM) demonstrated good activity in cell based assay and selectivity against a panel of human kinases. A co-complex TTK X-ray crystal structure and results of a xenograft study with TTK inhibitors from this class are described.
Subject(s)
Amides/pharmacology , Benzeneacetamides/pharmacology , Cell Cycle Proteins/antagonists & inhibitors , Drug Discovery , Indazoles/pharmacology , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein-Tyrosine Kinases/antagonists & inhibitors , Amides/chemical synthesis , Amides/chemistry , Benzeneacetamides/chemical synthesis , Benzeneacetamides/chemistry , Cell Cycle Proteins/metabolism , Crystallography, X-Ray , Dose-Response Relationship, Drug , Humans , Indazoles/chemical synthesis , Indazoles/chemistry , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/chemistry , Protein Serine-Threonine Kinases/metabolism , Protein-Tyrosine Kinases/metabolism , Structure-Activity RelationshipABSTRACT
We used DNA microarray screening to identify Ckap2 (cytoskeleton associated protein 2) as a novel p53 target gene in a mouse erythroleukemia cell line. DNA damage induces human and mouse CKAP2 expression in a p53-dependent manner and p53 activates the Ckap2 promoter. Overexpressed Ckap2 colocalizes with and stabilizes microtubules. In p53-null cells, overexpression of Ckap2 induces tetraploidy with aberrant centrosome numbers, suggesting disturbed mitosis and cytokinesis. In p53-competent cells, Ckap2 does not induce tetraploidy but activates p53-mediated cell cycle arrest and apoptosis. Our data suggest the existence of a functional positive feedback loop in which Ckap2 activates the G1 tetraploidy checkpoint and prevents aneuploidy.
Subject(s)
Aneuploidy , Cytoskeletal Proteins/genetics , Leukemia, Erythroblastic, Acute/genetics , Tumor Suppressor Protein p53/genetics , Animals , Apoptosis/genetics , Cell Cycle/genetics , Centrosome/physiology , Cytoskeletal Proteins/metabolism , HCT116 Cells , Humans , Leukemia, Erythroblastic, Acute/pathology , Mice , Microtubules/metabolism , NIH 3T3 Cells , Oligonucleotide Array Sequence Analysis , Promoter Regions, Genetic , Transcriptional ActivationABSTRACT
RNA interference represents an exciting new technology that could have therapeutic applications for the treatment of viral infections. Hepatitis C virus (HCV) is a major cause of chronic liver disease and affects >270 million individuals worldwide. The HCV genome is a single-stranded RNA that functions as both a messenger RNA and replication template, making it an attractive target for the study of RNA interference. Double-stranded small interfering RNA (siRNA) molecules designed to target the HCV genome were introduced through electroporation into a human hepatoma cell line (Huh-7) that contained an HCV subgenomic replicon. Two siRNAs dramatically reduced virus-specific protein expression and RNA synthesis to levels that were 90% less than those seen in cells treated with negative control siRNAs. These same siRNAs protected naive Huh-7 cells from challenge with HCV replicon RNA. Treatment of cells with synthetic siRNA was effective >72 h, but the duration of RNA interference could be extended beyond 3 weeks through stable expression of complementary strands of the interfering RNA by using a bicistronic expression vector. These results suggest that a gene-therapeutic approach with siRNA could ultimately be used to treat HCV.
