REVIEW

Cell Research (2002); 12(5-6):311-320

The role of nitric oxide in cancer

Weiming XU^1,*, Li Zhi LIU¹, Marilena LOIZIDOU², Mohamed AHMED¹, Ian G CHARLES¹

¹Wolfson Institute for Biomedical Research, Cruciform Building, Gower Street, UCL, London, WC1 E 6AU, UK
²Department of Surgery, Charles Bell House, 67-73 Riding House Street, UCL, London W1W 7EJ, UK

Corresponding author: Dr. Weiming XU, Wolfson Institute for Biomedical Research. University College London, Cruciform Building, Gower Street, London WC1E 6AU.UK. Fax: 44207813 2846 Tel: 442076796209 Email: w.xu@ucl.ac.uk.

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Abbreviations: NO, nitric oxide; NOS, nitric oxide synthase; iNOS, inducible nitric oxide synthase; eNOS, endothelial nitric oxide synthase; nNOS, neuronal nitric oxide synthase; PARP, poly(ADP-ribose) polymerase; DNA-PK, DNA-dependent protein kinase; DNA-PKcs, catalytic subunit of DNA-PK; BH4, tetrahydrobiopterin; FAD, flavin adenosine dinucleotide; FMN,flavin mononucleotide; sGC, soluble guanylate cyclase; VEGF, vascular endothelial growth factor.

 Nitric oxide (NO) is a pleiotropic regulator, critical to numerous biological processes, including vasodilatation, neurotransmission and macrophage-mediated immunity. The family of nitric oxide synthases (NOS) comprises inducible NOS (iNOS), endothelial NOS (eNOS), and neuronal NOS (nNOS). Interestingly, various studies have shown that all three isoforms can be involved in promoting or inhibiting the etiology of cancer. NOS activity has been detected in tumour cells of various histogenetic origins and has been associated with tumour grade, proliferation rate and expression of important signaling components associated with cancer development such as the oestrogen receptor. It appears that high levels of NOS expression (for example, generated by activated macrophages) may be cytostatic or cytotoxic for tumor cells, whereas low level activity can have the opposite effect and promote tumour growth. Paradoxically therefore, NO (and related reactive nitrogen species) may have both genotoxic and angiogenic properties. Increased NO-generation in a cell may select mutant p53 cells and contribute to tumour angiogenesis by upregulating VEGF. In addition, NO may modulate tumour DNA repair mechanisms by upregulating p53, poly(ADP-ribose) polymerase (PARP) and the DNA-dependent protein kinase (DNA-PK). An understanding at the molecular level of the role of NO in cancer will have profound therapeutic implications for the diagnosis and treatment of disease.

Key words: nitric oxide, oestrogen, cancer, p53, PARP, DNA-PKcs.