Aurora kinases play an essential role in orchestrating chromosome alignment, segregation and cytokinesis during mitotic progression, with both aurora-A and B frequently over-expressed in a variety of human malignancies including those of leukaemic origin. Acute myeloid leukaemia (AML) is a heterogeneous clonal disorder of haematopoietic progenitor cells whose prognosis is particularly poor and where standard induction therapy has changed little over the past thirty years. This thesis evaluated the effects of AZD1152-hQPA (barasertib-hQPA), a highly selective inhibitor of aurora-B kinase, in AML cell lines and primary samples. Inhibition of phospho-Histone H3 (pHH3) on serine 10 can be used as a biomarker for AZD1152-hQPA activity and an assay was optimized to measure pHH3 in our cell lines and primary samples. AZD1152-hQPA inhibited pHH3 in our cell lines resulting in polyploid cells, apoptosis, and cell death, irrespective of cellular p53 status. Over-expression of the ATP-binding cassette (ABC) drug transporter proteins P-glycoprotein (Pgp) and Breast cancer resistance protein (BCRP) is a major obstacle for chemotherapy in many tumour types with Pgp conferring particularly poor prognosis in AML. A cell line which over-expresses Pgp was developed by selecting for daunorubicin (DNR) resistance in OCI-AML3 cells. Pgp and also BCRP expressing AML cell lines were found to be resistant to AZD1152-hQPA and it was found that AZD1152-hQPA is effluxed by these transporters. pHH3 inhibition by low dose AZD1152-hQPA was seen in all of the primary samples tested with Pgp and BCRP positive samples being less sensitive. However, 50% inhibition of pHH3 by AZD1152-hQPA was achieved in 94.6% of these samples. The FLT3-ITD-expressing MOLM-13 and MV4-11 cell lines were particularly sensitive to AZD1152-hQPA. Internal tandem duplications (ITDs) within the FLT3 tyrosine kinase receptor are found in approximately 25% of AML patients and are associated with a poor prognosis. It was demonstrated that AZD1152-hQPA directly targets phosphorylated FLT3 in the FLT3-ITD cell lines along with inhibiting its downstream target pSTAT5. FLT3-ITD primary samples were particularly sensitive to clonogenic inhibition and pSTAT5 down-regulation after treatment with AZD1152-hQPA compared with FLT3 wild-type (WT) samples.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:570355 |
| Date | January 2012 |
| Creators | Grundy, Martin |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/12758/ |
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