Investigating the role of BCL-2 family members in chemoresistance in adult and paediatric core-binding factor acute myeloid leukaemia

Lander, Nicola (2025) Investigating the role of BCL-2 family members in chemoresistance in adult and paediatric core-binding factor acute myeloid leukaemia. MSc(R) thesis, University of Glasgow.

Abstract

Paediatric and adult acute myeloid leukaemia (AML) are distinct diseases with different molecular and genetic signatures. Core-binding factor (CBF) AML is a subgroup of AML with chromosomal translocations [t(8;21)] or inversions [inv(16)]. Patients with CBF AML are considered to have favourable prognosis, despite this, relapse and chemoresistance is common in this subgroup.

Changes in apoptotic pathways have been demonstrated to contribute to resistance to established chemotherapies, such as cytarabine (Ara-C), in AML. BH3 mimetics have shown promise for the treatment of AML, however the use of BH3 mimetics in patients with CBF AML that are resistant to Ara-C remains unclear. Therefore, the broad aim of this project was to determine the role of apoptotic proteins in resistance to Ara-C using t(8;21) and inv(16) CBF AML cell lines. This project also sought to assess the use of BH3 profiling as a biomarker of response to BH3 mimetics in CBF AML.

To achieve this, Ara-C resistant models were generated using escalating doses of Ara-C. Baseline BH3 profiling was used to determine how acquisition of Ara-C resistance affected apoptotic priming of CBF AML cell lines. The dependency of these cell lines on anti-apoptotic proteins was assessed using intracellular staining and measurement of response to BH3 mimetics. Dynamic BH3 profiling was performed and compared to response to BH3 mimetics by apoptosis assay.

This project demonstrated that Ara-C resistance has different impacts on the apoptotic priming of paediatric t(8;21) Kasumi-1 and adult inv(16) ME-1 AML cell lines. In both Ara-C resistant cell lines, dynamic BH3 profiling using cytochrome c release recapitulated the apoptotic response typically seen with BCL-2 inhibition. Particularly noteworthy was the up regulation of MCL-1 expression in the resistant lines, suggesting increased reliance on this anti-apoptotic protein for survival. However, treatment with the selective MCL-1 inhibitor, S63845,failed to enhance cytochrome c release or induce apoptosis. In contrast, venetoclax, a BCL-2 inhibitor, induced greater cytotoxicity in Ara-C–resistant ME-1, but not in Kasumi-1.

Results of this project highlight the complexity of BCL-2 family member interactions and highlight that it may not be possible to infer functional apoptotic dependencies from the expression levels of anti-apoptotic proteins. These results suggest that there is a potential for pre-treatment with Ara-C to increase response to venetoclax. However, further work is needed to determine the most effective sequence of treatment with Ara-C and BH3 mimetics. This project adds to previous evidence which suggests that the use of dynamic BH3 profiling for prediction of response to BH3 mimetics may be helpful.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Subjects: Q Science > QR Microbiology; Q Science > QR Microbiology > QR180 Immunology
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Cancer Sciences
• Supervisor's Name: Copland, Professor Mhairi
• Date of Award: 2025
• Depositing User: Theses Team
• Unique ID: glathesis:2025-85271
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 30 Jun 2025 14:37
• Last Modified: 30 Jun 2025 14:40
• Thesis DOI: 10.5525/gla.thesis.85271
• URI: https://theses.gla.ac.uk/id/eprint/85271