Nitric oxide synthase and breast cancer: role of TIMP-1 in NO-mediated Akt activation

PLoS One. 2012;7(9):e44081. doi: 10.1371/journal.pone.0044081. Epub 2012 Sep 5.

Abstract

Prediction of therapeutic response and cancer patient survival can be improved by the identification of molecular markers including tumor Akt status. A direct correlation between NOS2 expression and elevated Akt phosphorylation status has been observed in breast tumors. Tissue inhibitor matrix metalloproteinase-1 (TIMP-1) has been proposed to exert oncogenic properties through CD63 cell surface receptor pathway initiation of pro-survival PI3k/Akt signaling. We employed immunohistochemistry to examine the influence of TIMP-1 on the functional relationship between NOS2 and phosphorylated Akt in breast tumors and found that NOS2-associated Akt phosphorylation was significantly increased in tumors expressing high TIMP-1, indicating that TIMP-1 may further enhance NO-induced Akt pathway activation. Moreover, TIMP-1 silencing by antisense technology blocked NO-induced PI3k/Akt/BAD phosphorylation in cultured MDA-MB-231 human breast cancer cells. TIMP-1 protein nitration and TIMP-1/CD63 co-immunoprecipitation was observed at NO concentrations that induced PI3k/Akt/BAD pro-survival signaling. In the survival analysis, elevated tumor TIMP-1 predicted poor patient survival. This association appears to be mainly restricted to tumors with high NOS2 protein. In contrast, TIMP-1 did not predict poor survival in patient tumors with low NOS2 expression. In summary, our findings suggest that tumors with high TIMP-1 and NOS2 behave more aggressively by mechanisms that favor Akt pathway activation.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breast Neoplasms / enzymology*
  • CD36 Antigens / biosynthesis
  • Enzyme Activation
  • Female
  • Gene Expression Regulation, Enzymologic*
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Immunohistochemistry / methods
  • Microscopy, Confocal / methods
  • Nitric Oxide / metabolism*
  • Nitric Oxide Synthase / physiology*
  • Oligonucleotides, Antisense / genetics
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Signal Transduction
  • Tissue Inhibitor of Metalloproteinase-1 / physiology*
  • Treatment Outcome

Substances

  • CD36 Antigens
  • Oligonucleotides, Antisense
  • TIMP1 protein, human
  • Tissue Inhibitor of Metalloproteinase-1
  • Nitric Oxide
  • Nitric Oxide Synthase
  • Proto-Oncogene Proteins c-akt