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Hypoxia-induced nitric oxide production and tumour perfusion is inhibited by pegylated arginine deiminase (ADI-PEG20).

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Cane, Gaelle 
Robson, Mathew 
Gaude, Edoardo 
Howat, William J 


The hypoxic tumour microenvironment represents an aggressive, therapy-resistant compartment. As arginine is required for specific hypoxia-induced processes, we hypothesised that arginine-deprivation therapy may be useful in targeting hypoxic cancer cells. We explored the effects of the arginine-degrading agent ADI-PEG20 on hypoxia-inducible factor (HIF) activation, the hypoxia-induced nitric oxide (NO) pathway and proliferation using HCT116 and UMUC3 cells and xenografts. The latter lack argininosuccinate synthetase (ASS1) making them auxotrophic for arginine. In HCT116 cells, ADI-PEG20 inhibited hypoxic-activation of HIF-1α and HIF-2α, leading to decreased inducible-nitric oxide synthase (iNOS), NO-production, and VEGF. Interestingly, combining hypoxia and ADI-PEG20 synergistically inhibited ASS1. ADI-PEG20 inhibited mTORC1 and activated the unfolded protein response providing a mechanism for inhibition of HIF and ASS1. ADI-PEG20 inhibited tumour growth, impaired hypoxia-associated NO-production, and decreased vascular perfusion. Expression of HIF-1α/HIF-2α/iNOS and VEGF were reduced, despite an increased hypoxic tumour fraction. Similar effects were observed in UMUC3 xenografts. In summary, ADI-PEG20 inhibits HIF-activated processes in two tumour models with widely different arginine biology. Thus, ADI-PEG20 may be useful in the clinic to target therapy-resistant hypoxic cells in ASS1-proficient tumours and ASS1-deficient tumours.



Animals, Arginine, Argininosuccinate Synthase, Basic Helix-Loop-Helix Transcription Factors, Blotting, Western, Cell Hypoxia, Cell Line, Tumor, HCT116 Cells, Humans, Hydrolases, Hypoxia, Hypoxia-Inducible Factor 1, alpha Subunit, Mechanistic Target of Rapamycin Complex 1, Mice, SCID, Multiprotein Complexes, Neoplasms, Nitric Oxide, Nitric Oxide Synthase Type II, Perfusion, Polyethylene Glycols, TOR Serine-Threonine Kinases, Tumor Burden, Unfolded Protein Response, Vascular Endothelial Growth Factor A, Xenograft Model Antitumor Assays

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Springer Science and Business Media LLC
Wellcome Trust (096956/Z/11/Z)
Department of Health (via National Institute for Health Research (NIHR)) (NF-SI-0514-10122)
Medical Research Council (MC_UU_12022/6)
Thanks to Dr John Bomalaski, (Polaris Pharmaceuticals, Inc) for supplying the ADI-PEG20, to Dr Simon S Hoer for useful discussions and to members of Histopathology/ISH (CRUK Cambridge Institute, UK) for IHC and imaging assistance. This work was supported by the Wellcome Trust and the NIHR Cambridge Biomedical Research Centre Senior Investigator Awards (to P.H.M., supporting N.B.), EU FP7 Metoxia Grant agreement no. 222741 (to P.H.M., supporting G.C.), UCL Cancer Research UK Centre (to M.R.), King’s College London and UCL Comprehensive Cancer Imaging Centre, Cancer Research UK and EPSRC in association with the Medical Research Council (MRC), the DoH (England: to R.B.P.), MRC Cancer Unit Core Funding (to C.F., supporting E.G.).