ECE2018 Guided Posters Adrenal clinical (10 abstracts)
Nicotinamide Nucleotide Transhydrogenase as a novel treatment target in adrenocortical carcinoma
Vasileios Chortis 1, , Angela Taylor 1, , Craig Doig 1, , Mark Walsh 3 , Eirini Meimaridou 4 , Carl Jenkinson 1, , Giovanny Rodriguez-Blanco 5 , Cristina Ronchi 1, , Alisha Jaffri 1, , Louise Metherell 6 , Daniel Hebenstreit 3 , Warwick Dunn 5 , Wiebke Arlt 1, & Paul Foster 1,
1Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK; 2Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK; 3School of Life Sciences, University of Warwick, Warwick, UK; 4London Metropolitan Hospital, London, UK; 5School of Biosciences, University of Birmingham, Birmingham, UK; 6Centre for Endocrinology, Queen Mary University of London, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, UK.
Adrenocortical Carcinoma (ACC) is an aggressive malignancy with poor response to chemotherapy. Here we evaluated a potential new treatment target for ACC, focusing on the mitochondrial NADPH generator Nicotinamide Nucleotide Transhydrogenase (NNT). NNT has a central role within mitochondrial antioxidant pathways, protecting cells from oxidative stress. Inactivating human NNT mutations result in congenital adrenal insufficiency. We hypothesized NNT silencing in ACC cells will induce toxic levels of oxidative stress. To explore this hypothesis, we transiently knocked down NNT in NCI-H295R ACC cells. As predicted, this manipulation increased intracellular levels of oxidative stress; this resulted in a pronounced suppression of cell proliferation and higher apoptotic rates, as well as sensitization of cells to chemically induced oxidative stress. Steroidogenesis was paradoxically stimulated by NNT loss, as demonstrated by mass spectrometry-based steroid profiling and real-time PCR. Pharmacological inhibition of antioxidant pathways downstream of NNT also displayed potent anti-tumour effects in vitro. Next, we generated a stable NNT knockdown model in the same cell line to investigate the longer-lasting effects of NNT silencing. After long-term culture, cells adapted metabolically to chronic NNT knockdown, restoring their redox balance and resilience to oxidative stress, although their proliferation remained suppressed. This was associated with higher rates of oxygen consumption. The molecular pathways underpinning these responses were explored in detail by RNA sequencing and non-targeted metabolome analysis. Transient NNT knockdown induced major alterations in core molecular pathways that control cellular proliferation and viability, and had far-reaching effects on cell metabolism. Stable knockdown was associated with changes in protein processing in the Endoplasmic Reticulum and up-regulation of polyamine synthesis, which may facilitate the observed adaptation to oxidative stress. Our study provides the first pre-clinical evidence of the therapeutic merit of antioxidant targeting in ACC as well as illuminating the long-term adaptive response of cells to oxidative stress.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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