Mechanisms of action of 3’-deoxyadenosine in treating clear cell renal cell carcinoma
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Although treatment strategies for advanced and metastatic clear cell renal cell carcinoma (ccRCC) have markedly evolved with the recent use of immune-checkpoint inhibitor (ICI)-based combinations, most patients eventually develop resistance to these therapies. Therefore, there is still an urgent need for the development of effective treatment options. NUC-7738, a novel ProTide transformation of the nucleoside analogue 3ﹶ-deoxyadenosine, releases 3ﹶ-deoxyadenosine monophosphate (3’-dAMP) in cells which is then phosphorylated to the di- (3’-dADP) and tri-phosphate forms (3’-dATP). 3’-dAMP might have the ability to activate AMP-activated protein kinase (AMPK), a key cellular energy sensor, and thus disrupt metabolic homeostasis in cancer cells. Furthermore, 3’-dATP might interfere with RNA synthesis affecting protein expression and survival of cancer cells. The ability of NUC-7738 to activate AMPK through phosphorylation of Th172 was tested in ccRCC cell lines and ex vivo tissue slices of ccRCC from patients. The effect of NUC-7738 on mRNA synthesis and polyadenylation was investigated in two ccRCC cell lines, 786-O and 769-P. AMPK activation by NUC-7738 showed inter-replicate variability and inter-patient variability in ccRCC cell lines and ex vivo tissue slices, respectively, indicating the complexity of the regulation of AMPK phosphorylation. Moreover, mass spectrometry analysis showed that 3’-dATP is the main active metabolite of NUC-7738. Transcriptome data analysis showed mitochondrial gene transcripts of electron transport chain (ETC) complexes were the most significantly altered in both 786-O and 769-P cell lines, with lower expression levels in response to NUC-7738 treatment. This was accompanied by downregulation of the protein expression of ETC complexes subunits. NUC-7738 induced the intrinsic pathway of apoptosis in these cells through the release of cytochrome c from mitochondria and the subsequent activation of caspases -9 and -7. These data suggest that NUC-7738 might inhibit tumour cells growth and proliferation through the inhibition of mitochondrial respiration and the subsequent induction of apoptosis.
Thesis, PhD Doctor of Philosophy
Embargo Date: 2024-05-16
Embargo Reason: Thesis restricted in accordance with University regulations. Restricted until 16th May 2024
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