A redox signaling mechanism for density-dependent inhibition of cell growth

Giovanni Pani, Renata Colavitti, Barbara Bedogni, Rosanna Anzevino, Silvia Borrello, Tommaso Galeotti

Research output: Contribution to journalArticle

119 Citations (Scopus)

Abstract

Reactive oxygen species (ROS) have recently drawn significant attention as putative mitogenic mediators downstream of activated growth factor receptors and oncogenic Ras; however, the possibility that a redox-related mechanism also operates in the negative control of cell proliferation by inhibitory signals has not been investigated thus far. Here we show that the arrest of growth induced by cell confluence ("contact inhibition") is due, at least in part, to a decrease in the steady-state levels of intracellular ROS and the consequent impairment of mitogenic redox signaling. In confluent fibroblast cultures, the decrease in the concentration of oxygen species was associated with diminished activity of the small GTPase Rac-1, a signal transducer directly involved in the ligand-dependent generation of oxygen-derived molecules, and was effectively mimicked by exposure of sparse cultures to dithiothreitol (DTT) and inhibitors of enzymes (phospholipase A2 and lipoxygenase) acting in the arachidonic acid cascade downstream of growth factor receptors and Rac-1. Sparse fibroblasts treated with nontoxic amounts of DTT underwent growth arrest, whereas a low concentration of hydrogen peroxide significantly increased thymidine incorporation in confluent cultures, demonstrating a causal link between redox changes and growth control by cell density. Removal of oxygen species from sparse cultures was accompanied by a drastic decrease of protein tyrosine phosphorylation after epidermal growth factor stimulation, which, at a biochemical level, reproduced the signaling hallmarks of contact inhibition. Moreover, the cytosolic tyrosine phosphatase SHP-2 was identified as a putative target for redox signaling by cell density because the enzyme itself and the associated substrates appear markedly dephosphorylated in both confluent and reductant-treated cells after exposure to epidermal growth factor, and SHP-2 enzymatic activity is strongly activated by DTT in vitro. Taken together, these data support a model in which impaired generation of ROS and increased protein tyrosine phosphatase activity impede mitogenic signaling in contact-inhibited cells.

Original languageEnglish (US)
Pages (from-to)38891-38899
Number of pages9
JournalJournal of Biological Chemistry
Volume275
Issue number49
DOIs
StatePublished - Dec 8 2000
Externally publishedYes

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Cell growth
Oxidation-Reduction
Dithiothreitol
Contact Inhibition
Reactive Oxygen Species
Growth Factor Receptors
Fibroblasts
Growth
Oxygen
Epidermal Growth Factor
Tyrosine
Cell Count
Phospholipase A2 Inhibitors
Phosphorylation
Protein Tyrosine Phosphatases
Lipoxygenase
Monomeric GTP-Binding Proteins
Phospholipases A2
Reducing Agents
Cell proliferation

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

A redox signaling mechanism for density-dependent inhibition of cell growth. / Pani, Giovanni; Colavitti, Renata; Bedogni, Barbara; Anzevino, Rosanna; Borrello, Silvia; Galeotti, Tommaso.

In: Journal of Biological Chemistry, Vol. 275, No. 49, 08.12.2000, p. 38891-38899.

Research output: Contribution to journalArticle

Pani, G, Colavitti, R, Bedogni, B, Anzevino, R, Borrello, S & Galeotti, T 2000, 'A redox signaling mechanism for density-dependent inhibition of cell growth', Journal of Biological Chemistry, vol. 275, no. 49, pp. 38891-38899. https://doi.org/10.1074/jbc.M007319200
Pani, Giovanni ; Colavitti, Renata ; Bedogni, Barbara ; Anzevino, Rosanna ; Borrello, Silvia ; Galeotti, Tommaso. / A redox signaling mechanism for density-dependent inhibition of cell growth. In: Journal of Biological Chemistry. 2000 ; Vol. 275, No. 49. pp. 38891-38899.
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