ABSTRACT
Although several plant-derived flavones inhibit aurora B kinase (aurB), quantitative relationships between the structural properties of plant-derived flavones and their inhibitory effects on aurB remain unclear. In this report, these quantitative structure-activity relationships were obtained. For quercetagetin, found in the Eriocaulon species, showing the best IC50 value among the flavone derivatives tested in this report, further biological tests were performed using cell-based assays, including Western blot analysis, flow cytometry, and immunofluorescence microscopy. In vitro cellular experiments demonstrated that quercetagetin inhibits aurB. The molecular-binding mode between quercetagetin and aurB was elucidated using in silico docking. Quercetagetin binds to aurB, aurA, and aurC and prevents the active phosphorylation of all three aurora kinases. In addition, quercetagetin triggers mitotic arrest and caspase-mediated apoptosis. These observations suggest that quercetagetin is an aurora kinase inhibitor. Induction of mitosis-associated tumor cell death by quercetagetin is a promising strategy for developing novel chemotherapeutic anticancer agents.
Subject(s)
Aurora Kinase B/antagonists & inhibitors , Flavones/chemistry , Protein Kinase Inhibitors/chemistry , Quantitative Structure-Activity Relationship , Apoptosis/drug effects , Aurora Kinase A/antagonists & inhibitors , Aurora Kinase A/metabolism , Aurora Kinase B/metabolism , Aurora Kinase C/antagonists & inhibitors , Aurora Kinase C/metabolism , Binding Sites , Chromones/chemistry , Chromones/isolation & purification , Chromones/toxicity , Eriocaulaceae/chemistry , Eriocaulaceae/metabolism , Flavones/isolation & purification , Flavones/toxicity , G2 Phase Cell Cycle Checkpoints/drug effects , HCT116 Cells , Humans , M Phase Cell Cycle Checkpoints/drug effects , Microscopy, Fluorescence , Molecular Docking Simulation , Phosphorylation/drug effects , Protein Kinase Inhibitors/isolation & purification , Protein Kinase Inhibitors/toxicity , Protein Structure, TertiaryABSTRACT
The Aurora family of serine/threonine kinases is essential for mitosis. Their crucial role in cell cycle regulation and aberrant expression in a broad range of malignancies have been demonstrated and have prompted intensive search for small molecule Aurora inhibitors. Indeed, over 10 of them have reached the clinic as potential anticancer therapies. We report herein the discovery and optimization of a novel series of tricyclic molecules that has led to SAR156497, an exquisitely selective Aurora A, B, and C inhibitor with in vitro and in vivo efficacy. We also provide insights into its mode of binding to its target proteins, which could explain its selectivity.
Subject(s)
Antineoplastic Agents/pharmacology , Aurora Kinases/antagonists & inhibitors , Benzimidazoles/pharmacology , Protein Kinase Inhibitors/pharmacology , Quinolones/pharmacology , Small Molecule Libraries/pharmacology , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/metabolism , Aurora Kinase A/antagonists & inhibitors , Aurora Kinase A/chemistry , Aurora Kinase A/metabolism , Aurora Kinase B/antagonists & inhibitors , Aurora Kinase B/chemistry , Aurora Kinase B/metabolism , Aurora Kinase C/antagonists & inhibitors , Aurora Kinase C/chemistry , Aurora Kinase C/metabolism , Aurora Kinases/chemistry , Aurora Kinases/metabolism , Benzimidazoles/chemistry , Benzimidazoles/metabolism , Female , HCT116 Cells , Humans , Mice, SCID , Models, Chemical , Models, Molecular , Molecular Structure , Neoplasms/drug therapy , Neoplasms/pathology , Protein Binding , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/metabolism , Protein Structure, Tertiary , Quinolones/chemistry , Quinolones/metabolism , Sf9 Cells , Small Molecule Libraries/chemistry , Small Molecule Libraries/metabolism , Xenograft Model Antitumor AssaysABSTRACT
The Aurora kinases, which include Aurora A (AURKA), Aurora B (AURKB) and Aurora C (AURKC), are serine/threonine kinases required for the control of mitosis (AURKA and AURKB) and meiosis (AURKC). Since their discovery nearly 20 years ago, Aurora kinases have been studied extensively in cell and cancer biology. Several early studies found that Aurora kinases are amplified and overexpressed at the transcript and protein level in various malignancies, including several types of leukemia. These discoveries and others provided a rationale for the development of small-molecule inhibitors of Aurora kinases as leukemia therapies. The first generation of Aurora kinase inhibitors did not fare well in clinical trials, owing to poor efficacy and high toxicity. However, the creation of second-generation, highly selective Aurora kinase inhibitors has increased the enthusiasm for targeting these proteins in leukemia. This review will describe the functions of each Aurora kinase, summarize their involvement in leukemia and discuss inhibitor development and efficacy in leukemia clinical trials.
Subject(s)
Aurora Kinase A/genetics , Aurora Kinase B/genetics , Aurora Kinase C/genetics , Leukemia/genetics , Aurora Kinase A/antagonists & inhibitors , Aurora Kinase B/antagonists & inhibitors , Aurora Kinase C/antagonists & inhibitors , Cell Cycle/genetics , Clinical Trials as Topic , Humans , Leukemia/drug therapy , Leukemia/pathology , Meiosis/genetics , Mitosis/genetics , Small Molecule Libraries/therapeutic useABSTRACT
Meiosis I (MI), the division that generates haploids, is prone to errors that lead to aneuploidy in females. Haspin is a kinase that phosphorylates histone H3 on threonine 3, thereby recruiting Aurora kinase B (AURKB) and the chromosomal passenger complex (CPC) to kinetochores to regulate mitosis. Haspin and AURKC, an AURKB homolog, are enriched in germ cells, yet their significance in regulating MI is not fully understood. Using inhibitors and overexpression approaches, we show a role for haspin during MI in mouse oocytes. Haspin-perturbed oocytes display abnormalities in chromosome morphology and alignment, improper kinetochore-microtubule attachments at metaphase I and aneuploidy at metaphase II. Unlike in mitosis, kinetochore localization remained intact, whereas the distribution of the CPC along chromosomes was absent. The meiotic defects following haspin inhibition were similar to those observed in oocytes where AURKC was inhibited, suggesting that the correction of microtubule attachments during MI requires AURKC along chromosome arms rather than at kinetochores. Our data implicate haspin as a regulator of the CPC and chromosome segregation during MI, while highlighting important differences in how chromosome segregation is regulated between MI and mitosis.
Subject(s)
Histones/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , Meiotic Prophase I , Oocytes/enzymology , Protein Serine-Threonine Kinases/metabolism , Adenosine Triphosphatases/metabolism , Aneuploidy , Animals , Aurora Kinase C/antagonists & inhibitors , Aurora Kinase C/metabolism , Cells, Cultured , Chromosome Segregation , DNA-Binding Proteins/metabolism , Female , Intracellular Signaling Peptides and Proteins/antagonists & inhibitors , Intracellular Signaling Peptides and Proteins/genetics , Kinetochores/enzymology , Meiotic Prophase I/drug effects , Mice , Microtubules/enzymology , Multiprotein Complexes/metabolism , Oocytes/drug effects , Phosphorylation , Protein Kinase Inhibitors/pharmacology , Protein Processing, Post-Translational , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein Serine-Threonine Kinases/genetics , Protein Transport , Signal Transduction , Threonine , Time Factors , TransfectionABSTRACT
Aurora kinases play important roles in cell division and are frequently overexpressed in human cancer. AMG 900 is a novel pan-Aurora kinase inhibitor currently being tested in Phase I clinical trials. We aimed to evaluate the in vitro activity of AMG 900 in a panel of 44 human breast cancer and immortalized cell lines and identify predictors of response. AMG 900 inhibited proliferation at low nanomolar concentrations in all cell lines tested. Response was further classified based on the induction of lethality. 25 cell lines were classified as highly sensitive (lethality at 10 nM of AMG 900 >10 %), 19 cell lines as less sensitive to AMG 900 (lethality at 10 nM of AMG 900 <10 %). Traditional molecular subtypes of breast cancer did not predict for this differential response. There was a weak association between AURKA amplification and response to AMG 900 (response ratio = 2.53, p = 0.09). mRNA expression levels of AURKA, AURKB, and AURKC and baseline protein levels of Aurora kinases A and B did not significantly associate with response. Cell lines with TP53 loss of function mutations (RR = 1.86, p = 0.004) and low baseline p21 protein levels (RR = 2.28, p = 0.0004) were far more likely to be classified as highly sensitive to AMG 900. AMG 900 induced p53 and p21 protein expression in cell lines with wt TP53. AMG 900 caused the accumulation of cells with >4 N DNA content in a majority of cell lines independently of sensitivity and p53 status. AMG 900 induced more pronounced apoptosis in highly sensitive p53-dysfunctional cell lines. We have found that AMG 900 is highly active in breast cancer cell lines and that TP53 loss of function mutations as well as low baseline expression of p21 protein predict strongly for increased sensitivity to this compound in vitro.
