This Article Full Text Full Text (PDF) Supplementary Data Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kopnin, P. B. Articles by Chumakov, P. M. Search for Related Content PubMed Articles by Kopnin, P. B. Articles by Chumakov, P. M.

Repression of Sestrin Family Genes Contributes to Oncogenic Ras-Induced Reactive Oxygen Species Up-regulation and Genetic Instability

¹ Engelhardt Institute of Molecular Biology; ² University of Oslo, Centre for Medical Studies in Russia; ³ Institute of Carcinogenesis, Russian Blokhin Cancer Research Center, Moscow, Russia; and ⁴ Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, Ohio

Requests for reprints: Boris P. Kopnin, Engelhardt Institute of Molecular Biology, 119991 Moscow, Russia. Phone: 7-095-324-1739; E-mail: bkopnin{at}yahoo.com or Peter M. Chumakov, Department of Molecular Genetics, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, OH 44195. Phone: 216-444-9540; E-mail: chumakp{at}ccf.org.

Oncogenic mutations within RAS genes and inactivation of p53 are the most common events in cancer. Earlier, we reported that activated Ras contributes to chromosome instability, especially in p53-deficient cells. Here we show that an increase in intracellular reactive oxygen species (ROS) and oxidative DNA damage represents a major mechanism of Ras-induced mutagenesis. Introduction of oncogenic H- or N-Ras caused elevated intracellular ROS, accumulation of 8-oxo-2'-deoxyguanosine, and increased number of chromosome breaks in mitotic cells, which were prevented by antioxidant N-acetyl-L-cysteine. By using Ras mutants that selectively activate either of the three major targets of Ras (Raf, RalGDS, and phosphatidylinositol-3-kinase) as well as dominant-negative Rac1 and RalA mutants and inhibitors of mitogen-activated protein kinase (MAPK)/extracellular signal–regulated kinases kinase-1 and p38 MAPKs, we have shown that several Ras effectors independently mediate ROS up-regulation. Introduction of oncogenic RAS resulted in repression of transcription from sestrin family genes SESN1 and SESN3, which encode antioxidant modulators of peroxiredoxins. Inhibition of mRNAs from these genes in control cells by RNA interference substantially increased ROS levels and mutagenesis. Ectopic expression of SESN1 and SESN3 from lentiviral constructs interfered with Ras-induced ROS increase, suggesting their important contribution to the effect. The stability of Ras-induced increase in ROS was dependent on a p53 function: in the p53-positive cells displaying activation of p53 in response to Ras, only transient (4–7 days) elevation of ROS was observed, whereas in the p53-deficient cells the up-regulation was permanent. The reversion to normal ROS levels in the Ras-expressing p53-positive cells correlated with up-regulation of p53-responsive genes, including reactivation of SESN1 gene. Thus, changes in expression of sestrins can represent an important determinant of genetic instability in neoplastic cells showing simultaneous dysfunctions of Ras and p53. [Cancer Res 2007;67(10):4671–8]