The Aurora Kinase Inhibitor AZD1152 Causes Perturbation of Cell Cycle Distribution in Cell Lines and Primary AML Samples

• Published in: Blood Vol. 106; no. 11; p. 2759
• Main Authors: Walsby, Elisabeth, Walsh, Val, Pepper, Chris, Mills, Ken, Burnett, Alan K.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 16.11.2005
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V106.11.2759.2759

Aurora kinases (AK) participate in chromosome separation during mitosis and are essential for mitotic processes and completion of cytokinesis. AK-A is found at the centrosome and spindle apparatus during prophase to telophase, while AK-B is seen in the midzone during anaphase of the cell cycle. Inhibition of these kinases may be a viable therapeutic strategy. AZD1152 is a specific AK inhibitor, designed to target cell division in proliferating tumour cells, with potential for activity in a wide range of tumours. In order to evaluate the potential utility of the AK inhibitor AZD1152 in acute myeloid leukaemia (AML), the expression levels of AK-A, -B, and -C were evaluated in a panel of myeloid cell lines (HL-60, NB4, NB4R2, U937, KG1, and K562) and in cells from 10 normal bone marrows and 240 AML patients using the Affymetrix gene expression system (Affymetrix Inc.) validated by real-time quantitative polymerase chain reaction in 105 patients. AK-C was absent in all samples, while AK-A and -B were present in 5% and 34%, respectively, of the AML patients and both were present in normal bone marrow samples. Expression levels did not correlate with age, sex, French-American-British classification or cytogenetic risk group. AML cell lines were incubated with a variable concentration of AK inhibitor (0.01 μM to 10 μM) for up to 72 h and the effects on viability, cell growth, cell cycle, and DNA content measured after 24 and 48 h exposure. This resulted in the accumulation of cells with 4N DNA content, indicating an increased proportion of cells in G2, and development of cells with DNA content greater than G2/M phase cells, on occasions showing 8N ploidy. This effect was time and dose dependent. At 24 h AK inhibitor caused a significant increase (p≤0.05) in the number of cells with 4N DNA content, suggestive of G2, or with greater than 4N DNA content at concentrations as low as 0.01 μM. Growth of HL-60 and NB4 cells was inhibited, following 72 h treatment with AK inhibitor (0.01 μM), by 50% and 90% (p<0.05), respectively. Incubation of AML samples (n=28) with AK inhibitor also showed an effect on the cell cycle, with a significant increase in G2 population (p≤0.05), and occasionally an increase of DNA content (p≤0.05) after 24 and 48 h at a minimum concentration of 1.0 μM. Flow cytometric analysis showed histone H3 phosphorylation was decreased, from around 3–5% in untreated cells, only in a proportion (~35%) of primary samples. The growth inhibition effects seen are combined with increased DNA content, which is consistent with the endoreduplication effects associated with these agents. AK-B is expressed in around one-third of AML patients, and agents targeted against this kinase may have therapeutic potential in AML.