Regulation of normal cell cycle progression by flavin-containing oxidases

Academic Article


  • Mechanisms underlying the role of reactive oxygen species (ROS) generated by flavin-containing oxidases in regulating cell cycle progression were examined in human and rodent fibroblasts. Incubation of confluent cell cultures with nontoxic/nonclastogenic concentrations of the flavoprotein inhibitor, diphenyleneiodonium (DPI), reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase activity and basal ROS levels, but increased proteolysis of cyclin D1, p21Waf1 and phospho-p38MAPK. When these cells were allowed to proliferate by subculture in DPI-free medium, an extensive G1 delay was observed with concomitant activation of p53/p21 Waf1 signaling and reduced phosphorylation of mitogen-activated kinases. Compensation for decreased oxidant generation by simultaneous exposure to DPI and nontoxic doses of the ROS generators, γ-radiation or t-butyl-hydroperoxide, attenuated the G1 delay. Whereas the DPI-induced G1 checkpoint was completely dependent on PHOX91, ATM and WAF1, it was only partially dependent on P53. Interestingly, G1 to S progression was not affected when another flavin-containing enzyme, nitric oxide synthase, was inhibited nor was it associated with changes in mitochondrial membrane potential. Proliferating cells treated with DPI also experienced a significant but attenuated delay in G2. We propose that ATM performs a critical function in mediating normal cellular proliferation that is regulated by nonphagocytic NAD(P)H oxidase enzymes activity, which may serve as a novel target for arresting cancer cells in G1. © 2008 Nature Publishing Group All rights reserved.
  • Authors

    Published In

  • Oncogene  Journal
  • Digital Object Identifier (doi)

    Pubmed Id

  • 15368893
  • Author List

  • Venkatachalam P; De Toledo SM; Pandey BN; Tephly LA; Carter AB; Little JB; Spitz DR; Azzam EI
  • Start Page

  • 20
  • End Page

  • 31
  • Volume

  • 27
  • Issue

  • 1