Reactive oxygen species mediate Cr(VI)-induced carcinogenesis through PI3K/AKT-dependent activation of GSK-3β/β-catenin signaling

Young Ok Son, Poyil Pratheeshkumar, Lei Wang, Xin Wang, Jia Fan, Dong Hern Kim, Ju Yeon Lee, Zhuo Zhang, Jeong Chae Lee, Xianglin Shi

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Cr(VI) compounds are known human carcinogens that primarily target the lungs. Cr(VI) produces reactive oxygen species (ROS), but the exact effects of ROS on the signaling molecules involved in Cr(VI)-induced carcinogenesis have not been extensively studied. Chronic exposure of human bronchial epithelial cells to Cr(VI) at nanomolar concentrations (10-100. nM) for 3. months not only induced cell transformation, but also increased the potential of these cells to invade and migrate. Injection of Cr(VI)-stimulated cells into nude mice resulted in the formation of tumors. Chronic exposure to Cr(VI) increased levels of intracellular ROS and antiapoptotic proteins. Transfection with catalase or superoxide dismutase (SOD) prevented Cr(VI)-mediated increases in colony formation, cell invasion, migration, and xenograft tumors. While chronic Cr(VI) exposure led to activation of signaling cascades involving PI3K/AKT/GSK-3β/β-catenin and PI3K/AKT/mTOR, transfection with catalase or SOD markedly inhibited Cr(VI)-mediated activation of these signaling proteins. Inhibitors specific for AKT or β-catenin almost completely suppressed the Cr(VI)-mediated increase in total and active β-catenin proteins and colony formation. In particular, Cr(VI) suppressed autophagy of epithelial cells under nutrition deprivation. Furthermore, there was a marked induction of AKT, GSK-3β, β-catenin, mTOR, and carcinogenic markers in tumor tissues formed in mice after injection with Cr(VI)-stimulated cells. Collectively, our findings suggest that ROS is a key mediator of Cr(VI)-induced carcinogenesis through the activation of PI3K/AKT-dependent GSK-3β/β-catenin signaling and the promotion of cell survival mechanisms via the inhibition of apoptosis and autophagy.

Original languageEnglish
Pages (from-to)239-248
Number of pages10
JournalToxicology and Applied Pharmacology
Issue number2
StatePublished - Sep 1 2013

Bibliographical note

Funding Information:
This research was supported by National Institutes of Health ( R01ES015518 , R01ES017244 , and R01ES02870 ).


  • Carcinogenesis
  • Cell transformation
  • Cr(VI)
  • Reactive oxygen species (ROS)
  • β-catenin

ASJC Scopus subject areas

  • Toxicology
  • Pharmacology


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