MMP-3 activation is involved in copper oxide nanoparticle-induced epithelial-mesenchymal transition in human lung epithelial cells

Abstract

Copper oxide nanoparticles (Nano-CuO) are widely used in medical and industrial fields and our daily necessities. However, the biosafety assessment of Nano-CuO is far behind their rapid development. Here, we investigated the adverse effects of Nano-CuO on normal human bronchial epithelial BEAS-2B cells, especially determined whether Nano-CuO exposure would cause dysregulation of MMP-3, an important mediator in pulmonary fibrosis, and its potential role in epithelial-mesenchymal transition (EMT). Our results showed that exposure to Nano-CuO, but not Nano-TiO₂, caused increased ROS generation, MAPKs activation, and MMP-3 upregulation. Nano-CuO-induced ROS generation was not observed in mitochondrial DNA-depleted BEAS-2B ρ⁰ cells, indicating that mitochondria may be the main source of Nano-CuO-induced ROS generation. Pretreatment of the cells with ROS scavengers or inhibitors or depleting mitochondrial DNA significantly attenuated Nano-CuO-induced MAPKs activation and MMP-3 upregulation, and pretreatment of cells with MAPKs inhibitors abolished Nano-CuO-induced MMP-3 upregulation, suggesting Nano-CuO-induced MMP-3 upregulation is through Nano-CuO-induced ROS generation and MAPKs activation. In addition, exposure of the cells to Nano-CuO for 48 h resulted in decreased E-cadherin expression and increased expression of vimentin, α-SMA, and fibronectin, which was ameliorated by MMP-3 siRNA transfection, suggesting an important role of MMP-3 in Nano-CuO-induced EMT. Taken together, our study demonstrated that Nano-CuO exposure caused mitochondrial ROS generation, MAPKs activation, and MMP-3 upregulation. Nano-CuO exposure also caused cells to undergo EMT, which was through Nano-CuO-induced dysregulation of ROS/MAPKs/MMP-3 pathway. Our findings will provide further understanding of the potential mechanisms involved in metal nanoparticle-induced various toxic effects including EMT and pulmonary fibrosis.

Keywords:

• CuO nanoparticles
• mitochondrial ROS
• MAPKs
• MMP-3
• epithelial-mesenchymal transition (EMT)

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contributions

YBZ, YM, JY, YZ, LM, and QZ designed and performed the experiments, analyzed the data, and interpreted the results of experiments. QZ conceived and supervised the study. The manuscript was written by YBZ, YM, and YZ, and revised critically by QZ. All authors read and approved the final manuscript.

Additional information

Funding

This work was partly supported by NIH [ES023693, ES028911, and HL147856], KSEF-148-RED-502-16-381, and Kentucky Lung Cancer Research Program to Dr. Qunwei Zhang. This work was also partly supported by P30ES030283 from the National Institute for Environmental Health Sciences.