Cr(VI) induces premature senescence through ROS-mediated p53 pathway in L-02 hepatocytes

Sci Rep. 2016 Oct 4:6:34578. doi: 10.1038/srep34578.

Abstract

Hexavalent Chromium [Cr(VI)], which can be found of various uses in industries such as metallurgy and textile dying, can cause a number of human disease including inflammation and cancer. Unlike previous research that focused on Cr(VI)-induced oxidative damage and apoptosis, this study placed emphasis on premature senescence that can be induced by low-dose and long-term Cr(VI) exposure. We found Cr(VI) induced premature senescence in L-02 hepatocytes, as confirmed by increase in senescence associated-β-galactosidase (SA-β-Gal) activity. Cr(VI) stabilized p53 through phosphorylation at Ser15 and increased expression of p53-transcriptional target p21. Mechanism study revealed Cr(VI) targeted and inhibited mitochondrial respiratory chain complex (MRCC) I and II to enhance reactive oxygen species (ROS) production. By applying antioxidant Trolox, we also confirmed that ROS mediated p53 activation. A tetracycline-inducible lentiviral expression system containing shRNA to p53 was used to knockout p53. We found p53 could inhibit pro-survival genes B-cell lymphoma-2 (Bcl-2), myeloid leukemia-1 (Mcl-1) and S phase related cell cycle proteins cyclin-dependent kinase 2 (CDK2), Cyclin E to induce premature senescence, and the functional role of ROS in Cr(VI)-induced premature senescence is depend on p53. The results suggest that Cr(VI) has a role in premature senescence by promoting ROS-dependent p53 activation in L-02 hepatocytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Cell Survival / drug effects
  • Cellular Senescence / drug effects*
  • Chromium / toxicity*
  • Electron Transport Complex I / metabolism
  • Electron Transport Complex II / metabolism
  • Hepatocytes
  • Humans
  • Phosphorylation / drug effects
  • Reactive Oxygen Species / metabolism*
  • Tumor Suppressor Protein p53 / metabolism*

Substances

  • Reactive Oxygen Species
  • TP53 protein, human
  • Tumor Suppressor Protein p53
  • Chromium
  • chromium hexavalent ion
  • Electron Transport Complex II
  • Electron Transport Complex I