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Identification of LDH-A as a therapeutic target for cancer cell killing via (i) p53/NAD(H)-dependent and (ii) p53-independent pathways

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posted on 23.02.2016, 09:40 by S. J. Allison, J. R. P. Knight, C. Granchi, R. Rani, F. Minutolo, J . Milner, R. M. Phillips
Most cancer cells use aerobic glycolysis to fuel their growth. The enzyme lactate dehydrogenase-A (LDH-A) is key to cancer’s glycolytic phenotype, catalysing the regeneration of nicotinamide adenine dinucleotide (NAD+) from reduced nicotinamide adenine dinucleotide (NADH) necessary to sustain glycolysis. As such, LDH-A is a promising target for anticancer therapy. Here we ask if the tumour suppressor p53, a major regulator of cellular metabolism, influences the response of cancer cells to LDH-A suppression. LDH-A knockdown by RNA interference (RNAi) induced cancer cell death in p53 wild-type, mutant and p53-null human cancer cell lines, indicating that endogenous LDH-A promotes cancer cell survival irrespective of cancer cell p53 status. Unexpectedly, however, we uncovered a novel role for p53 in the regulation of cancer cell NAD+ and its reduced form NADH. Thus, LDH-A silencing by RNAi, or its inhibition using a small-molecule inhibitor, resulted in a p53-dependent increase in the cancer cell ratio of NADH:NAD+. This effect was specific for p53+/+ cancer cells and correlated with (i) reduced activity of NAD+-dependent deacetylase sirtuin 1 (SIRT1) and (ii) an increase in acetylated p53, a known target of SIRT1 deacetylation activity. In addition, activation of the redox-sensitive anticancer drug EO9 was enhanced selectively in p53+/+ cancer cells, attributable to increased activity of NAD(P)H-dependent oxidoreductase NQO1 (NAD(P)H quinone oxidoreductase 1). Suppressing LDH-A increased EO9-induced DNA damage in p53+/+ cancer cells, but importantly had no additive effect in non-cancer cells. Our results identify a unique strategy by which the NADH/NAD+ cellular redox status can be modulated in a cancer-specific, p53-dependent manner and we show that this can impact upon the activity of important NAD(H)-dependent enzymes. To summarise, this work indicates two distinct mechanisms by which suppressing LDH-A could potentially be used to kill cancer cells selectively, (i) through induction of apoptosis, irrespective of cancer cell p53 status and (ii) as a part of a combinatorial approach with redox-sensitive anticancer drugs via a novel p53/NAD(H)-dependent mechanism.

Funding

This work was funded by Yorkshire Cancer Research (YCR): programme grant (JM), project grants (JM/SJA; SJA (B211)) and pump priming grant (JM/RMP). Funding for NHI-2 synthesis was from an EU Seventh Framework Programme grant (PIIF-GA-2011-299026) (FM/RR).

History

Citation

Oncogenesis (2014) 3, e102

Version

VoR (Version of Record)

Published in

Oncogenesis (2014) 3

Publisher

Nature Publishing Group

issn

2157-9024

eissn

2157-9024

Acceptance date

27/02/2014

Available date

23/02/2016

Publisher version

http://www.nature.com/oncsis/journal/v3/n5/full/oncsis201416a.html

Notes

Supplementary Information accompanies this paper on the Oncogenesis website http://www.nature.com/oncsis/journal/v3/n5/suppinfo/oncsis201416s1.html

Language

en