Constitutive intracellular production of iNOS and NO in human melanoma: possible role in regulation of growth and resistance to apoptosis

Nitric Oxide. 2008 Sep;19(2):133-7. doi: 10.1016/j.niox.2008.04.009. Epub 2008 Apr 22.


Human melanoma tumors cells are known to express the enzyme, inducible nitric oxide synthase (iNOS), which is responsible for cytokine induced nitric oxide (NO) production during immune responses. This constitutive expression of iNOS in many patients' tumor cells, as well as its strong association with poor patient survival, have led to the consideration of iNOS as a molecular marker of poor prognosis, as well as a possible target for therapy. The expression of iNOS in patient tumors was found to associate with nitrotyrosine, COX2, pSTAT3, and arginase. Using human melanoma patients' samples as well as cell lines, we have further evidence supporting intracellular NO production by detection of nitrotyrosine and also by use of DAF-2DA staining. Experiments were performed to scavenge the endogenous NO (with c-PTIO) resulting in melanoma cell growth inhibition; this was restored with SIN-1 (NO and O2-donor) providing data to support a functional role of this gas. Our goal is to understand the aberrant biology leading to this curious phenomenon, and to regulate it in favor of patient treatments.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Apoptosis*
  • Cell Line, Tumor
  • Cell Proliferation*
  • Cyclooxygenase 2 / analysis
  • Humans
  • Melanoma / metabolism
  • Melanoma / pathology*
  • Neoplasm Proteins / analysis
  • Nitric Oxide / physiology*
  • Nitric Oxide Synthase Type II / analysis*
  • STAT3 Transcription Factor / analysis
  • Tumor Cells, Cultured
  • Tyrosine / analogs & derivatives
  • Tyrosine / analysis


  • Neoplasm Proteins
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • Nitric Oxide
  • 3-nitrotyrosine
  • Tyrosine
  • NOS2 protein, human
  • Nitric Oxide Synthase Type II
  • Cyclooxygenase 2
  • PTGS2 protein, human