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Browsing by Subject "NAD metabolites"

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  • Asikainen, Virpi (2022)
    Chemoresistance is a significant contributor to the lethality of high-grade serous ovarian cancer (HGSOC). Treatment response to traditional platinum-based chemotherapy is poor, and the need for improvement is urgent, as more than 50% of the patients pass within 5-years from diagnosis. Mitochondrial metabolism has emerged as a potential target in HGSOC, and enhanced capacity in mitochondrial oxidative phosphorylation (OXPHOS) has been shown to correlate with a better chemoresponse. The vital metabolic cofactor for mitochondrial enzymatic reactions, during e.g. OXPHOS, is nicotinamide adenine dinucleotide (NAD+). It is now well-established that NAD+ precursor supplementation can boost intracellular NAD+ content and, consequently, mitochondrial function. In cancer, NAD+ boosting shows mitochondrial activation mediated anticancer and chemosensitizing effects and presents an intriguing route to modulate cancer metabolism and treatment response. In HGSOC, NAD+ metabolism and its association with tumours’ metabolic profile is poorly understood. Also, the impact of mitochondrial activation on HGSOC chemoresponse remains unexplored. This thesis aimed to evaluate patient-derived HGSOC tumour NAD metabolite content and its association with OXPHOS. Also, the aim was to explore whether in vitro NAD+ boosting promotes mitochondrial function and subsequently enhances chemosensitivity to platinum-based treatment. Thus, I measured the NAD metabolite concentrations in HGSOC tumours and two HGSOC cell lines, OVCAR-5 and COV318. The impact of NAD+ boosting on HGSOC cells OXPHOS and chemoresponse was assessed with respirometry and cell viability assays. I found that the HGSOC tumours presented alterations in NAD metabolite content, with an increase in the reduced forms and a decrease in the metabolite redox ratios. Also, the change in the NAD metabolite seemed to be impacted by the tumours’ anatomical location and OXPHOS capacity. In vitro HGSOC cells differed in their OXPHOS capacity, with the OXPHOS-high cell line exhibiting enhanced sensitivity to chemotherapy. The NAD+ boosting increased intracellular NAD+ content and mitochondrial OXPHOS without impacting the cells’ chemoresponse or growth. In conclusion, the altered NAD+ metabolism in HGSOC tumours presents potential target pathways for the disease with poor treatment response. The NAD+ boosting mediated metabolic modulation increased the OXPHOS capacity independently of the cell lines’ OXPHOS-status. In OXPHOS-low cells’ mitochondrial activation enhanced OXPHOS to the level of chemosensitive OXPHOS-high cells but did not alter the cell lines’ chemoresponse within a short-term treatment period. These observations have increased the understanding of NAD+ metabolism. Also, as a proof-of-principle, NAD+ boosting was presented as a tool for mitochondrial activation and metabolic modulation in HGSOC cells, opening an intriguing approach to explore HGSOC mitochondrial function and chemoresponse.