Oncotarget

Research Papers:

Mechanism of suppressors of cytokine signaling 1 inhibition of epithelial-mesenchymal transition signaling through ROS regulation in colon cancer cells: suppression of Src leading to thioredoxin up-regulation

Sung-Hoon Jung, Su-Min Kim and Choong-Eun Lee _

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Oncotarget. 2016; 7:62559-62571. https://doi.org/10.18632/oncotarget.11537

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Abstract

Sung-Hoon Jung1, Su-Min Kim1, Choong-Eun Lee1

1Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 440-746, Korea

Correspondence to:

Choong-Eun Lee, email: [email protected]

Keywords: suppressors of cytokine signaling, reactive oxygen species, Src, thioredoxin, EMT signaling

Received: February 26, 2016     Accepted: August 09, 2016     Published: August 23, 2016

ABSTRACT

Reactive oxygen species (ROS) participate in malignant progression of cancers including epithelial-mesenchymal transition (EMT). We have investigated the role of suppressors of cytokine signaling (SOCS)1 as an inhibitor of ROS-induced EMT using colon cancer cell lines transduced with SOCS1 and shSOCS1. Hydrogen peroxide treatment induced EMT features such as elevation of vimentin and Snail with a corresponding reduction of E-cadherin. The EMT markers are significantly decreased upon SOCS1 over-expression while increased under SOCS1 knock-down. SOCS1 inhibited ROS signaling pathways associated with EMT such as Src, Jak, and p65. Of note, strong up-regulation of Src activity in SOCS1-ablated cells was responsible for the elevated signaling leading to EMT, as shSrc or Src inhibitor abolished the shSOCS1-induced promotion of EMT response. Suppression of ROS-inducible EMT markers and invasion in SOCS1 over-expressing cells correlated with significantly low intracellular ROS levels in these cells. Analysis of antioxidant enzymes in SOCS1-transduced cells revealed a selective up-regulation of thioredoxin (Trx1), while thioredoxin ablation restored ROS levels and the associated EMT markers. As a mechanism of thioredoxin up-regulation by SOCS1, inhibition of Src activity promoting nuclear translocation of Nrf-2 is proposed. Taken together, our data strongly indicate that SOCS1 antagonizes EMT by suppressing Src activity, leading to thioredoxin expression and down-regulation of ROS levels in colon cancer cells.


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