Modulation of novel drug targets in neurotransmitter signalling to eradicate leukaemic stem cells in chronic myeloid leukaemia

Ritchie, Jake Thomas Shirley (2019) Modulation of novel drug targets in neurotransmitter signalling to eradicate leukaemic stem cells in chronic myeloid leukaemia. PhD thesis, University of Glasgow.

Abstract

The most significant obstacle in developing a cure for chronic myeloid leukaemia (CML) is the existence of TKI-insensitive leukaemic stem cells (LSCs) in patients with residual disease. Previous transcriptomics analysis pointed to neurotransmitter pathways as being active in LSC and normal haematopoietic stem cells (HSCs), but significantly deregulated between them. It was therefore hypothesised that these pathways may also have critical roles in LSC survival. To identify drug-able targets in these pathways, compound screens were performed in CML primary CD34+ cells and cell lines with 658 neurotransmitter-modulating compounds. These screens identified 120 significant hits and revealed that compounds targeting the dopaminergic signalling pathway were significantly over-represented (p<0.0001). A secondary screen of primary CML CD34+ versus non-CML CD34+ cells with these compounds, complemented with additional phenotypic assays (CFC and LTC-IC), revealed a number of compounds targeting the dopaminergic pathway with significant therapeutic windows. The D2-like dopamine receptor (DR) antagonist fluphenazine was identified as among those as having the greatest therapeutic potential. While fluphenazine had very little effect on the bulk CD34+ leukaemic cells, long term colony assays revealed that it selectively eradicates LSCs, reducing LTC-IC output to 5% compared to untreated control (p<0.001) whilst having very little effect on the LTC-IC output of HSCs. This is perhaps due to that fluphenazine +/- TKI inhibits a number of known LSC survival factors including PRKCH, FOXO3a and c-Myc in CML cell lines. Flow cytometry has revealed that LSCs express D2-like dopamine receptors at significantly higher levels compared to HSCs suggesting that fluphenazine’s mechanism of action in CML cells is likely through specific D2-like receptors. Furthermore, fluphenazine when combined with the TKI nilotinib is highly effective at eradicating LSCs compared to nilotinib alone in in vivo mouse models of CML. These results indicate that antagonising dopaminergic signalling could provide a novel mechanism to selectively eliminate the LSC population in CML whilst sparing HSCs.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Chronic myeloid leukaemia, CML, leukaemic stem cell, novel therapy, dopamine.
• Subjects: Q Science > Q Science (General); Q Science > QH Natural history > QH301 Biology; Q Science > QH Natural history > QH426 Genetics
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Cancer Sciences
• Supervisor's Name: Vetrie, Prof. David and Scott, Dr. Mary
• Date of Award: 2019
• Embargo Date: 24 February 2024
• Depositing User: Jake Ritchie
• Unique ID: glathesis:2019-79052
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 28 Feb 2020 09:52
• Last Modified: 06 Apr 2023 11:01
• Thesis DOI: 10.5525/gla.thesis.79052
• URI: https://theses.gla.ac.uk/id/eprint/79052