Saudi Cultural Missions Theses & Dissertations
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Item Restricted Exploring Mechanisms of Sensitivity and Resistance to Novel Therapeutic Targets in Aggressive Blood Malignancies.(University of Leicester, 2024-02-13) Alzahrani, Wael Ibrahim H; Macip, SalvadorChemotherapy is commonly used to induce cell death in diffuse large B-cell lymphoma (DLBCL) and acute myeloid leukaemia (AML), but not all patients respond well, and toxicities may be great; there remains a need for effective precision cancer medicines. Dihydroorotate dehydrogenase (DHODH) is a mitochondrial matrix enzyme involved in de novo pyrimidine synthesis, playing a crucial role in DNA and RNA synthesis. CRISPR studies have shown that DHODH is an essential gene in haematologic cells. BAY 2402234 is a highly specific DHODH inhibitor. My studies revealed that BAY 2402234 induced caspase-dependent apoptosis, uridine exogenous addition rescued cells from pyrimidine starvation and showed potential for synergy with BH3 mimetics in some DLBCL and AML cell lines. DHODHi are toxic and ineffective for cancer patients in clinical trials, so acquired resistance to BAY 2402234 was investigated in the OCI-LY19 DLBCL cell line, which is highly sensitive to DHODHi (IC50 of 5pM). In a derived cell line with 200,000-fold resistance, I identified a novel DHODH missense mutation (A58T), which was predicted to prevent the binding of BAY 2402234 but not to interfere with DHODH’s function. RNA-Seq experiments exhibited significant gene expression changes occurring in hallmark pathways with a specific emphasis on MYC OXPHOS and glycolytic targets. Additionally, elevated expression of PI3KCD was observed. Copanlisib a pan-PI3Ki synergised with BAY 2202234 in resistant OCI-LY19 cells, prompting its evaluation as a potential sensitiser. Collectively these findings provide insights for developing effective DHODHi combination therapies that might mitigate toxicities seen with DHODHi in vivo. I also investigated various approaches, such as a BCL-2 inhibitor, or other BH3 mimetics in combination with 14-3-3σ stabilisers FC-A and WR-1065, or MDM2 antagonist and inhibiting the B-cell receptor pathway using Tirabrutinib, CAL-101. DLBCL and AML cell lines showed diverse responses based on subtype and genetics, underlining the need for personalised treatments.34 0Item Restricted Understanding the influence of radiotherapy in HCC cell lines, alone or when in combination with BCL-2 inhibitors(Saudi Digital Library, 2023-09-18) Alqarafi, Bashaer; Bird, Thomas; May, StephanieHepatocellular carcinoma (HCC) is the predominant form of liver cancer, accounting for approximately 90% of all cases. It is the third most common cause of cancer-related mortality worldwide. The development of this disease is associated with several risk factors, including liver inflammatory diseases, such as cirrhosis. Treatment options for advanced HCC are limited as the majority of patients present with incurable disease. Stereotactic ablative radiotherapy (SBRT) has recently been approved for patients who are not eligible for curative options. SBRT is reported to provide good tumour control, but patients often succumb to recurrent or metastatic disease. This could be due to a cancer's ability to evade cell death. Therefore, there is a significant opportunity for combining SBRT and systemic therapy to improve treatment outcomes. The intrinsic apoptosis pathway plays a crucial role in programmed cell death. Disruption of this pathway can lead to uncontrolled cell division. Therefore, there is untapped potential in combining SBRT with treatments that promote cell death (termed BH3-mimetics). The aims of this study were to: 1) assess the radiosensitivity of an HCC cell line (Hep53.4) using in vitro clonogenic assays; 2) evaluate the potential synergistic effect of combination SBRT and BH3-mimetic treatment (e.g. ABT263) using in vitro cell viability assays, and 3) examine whether SBRT causes radiation-induced liver disease in vivo in murine models using immunohistochemistry. Key findings of this study indicate that Hep53.4 cells are radiosensitive and combination treatment with 6Gy irradiation and ABT263, had a synergistic killing effect. Additionally, histological analysis of collagen markers revealed that SBRT effectively spares healthy liver tissue, whilst modifying the tumour collagen deposition compared to non-irradiated tumour controls. While in vitro data displays promising outcomes regarding the synergistic potential of systemic BH3-mimetic therapy and SBRT, further pre-clinical studies are imperative to establish its applicability in the clinical setting.25 0