Luteolin Alleviates Epithelial‐Mesenchymal Transformation Induced by Oxidative Injury in ARPE‐19 Cell <i>via</i> Nrf2 and AKT/GSK‐3<i>β</i> Pathway
Lan Chen, Yanqing Zhu, Jie Zhou, Rui Wu, Ning Yang, Qinbin Bao, Xin-Rong Xu
Abstract
Oxidative stress plays a critical role in age‐related macular degeneration (AMD), and epithelial‐mesenchymal transition (EMT) is involved in this process. The aim of this study was to investigate the protective effects of luteolin, a natural flavonoid with strong antioxidant activity, on H 2 O 2 ‐induced EMT in ARPE‐19 cells. ARPE‐19 cells were incubated with H 2 O 2 at 200 μΜ to induce oxidative stress‐associated injury. Cell viability assay showed that luteolin at 20 and 40 μ M significantly promoted cell survival in H 2 O 2 ‐treated ARPE‐19 cells. Luteolin also markedly protected ARPE‐19 cells from H 2 O 2 ‐induced apoptosis. Cell migration assay presented that luteolin significantly reduced H 2 O 2 ‐induced migration in APRE‐19 cells. EMT in ARPE‐19 cells was detected by western blotting and immunofluorescence. The results showed that H 2 O 2 significantly upregulated the expression of α ‐SMA and vimentin and downregulated the expression of ZO‐1 and E‐cadherin, while cells pretreated with luteolin showed a reversal. Meanwhile, the assessment of effects of luteolin on the Nrf2 pathway indicated that luteolin promoted Nrf2 nuclear translocation and upregulated the expressions of HO‐1 and NQO‐1. In addition, luteolin significantly increased the activities of SOD and GSH‐PX and decreased intracellular levels of ROS and MDA in H 2 O 2 ‐treated ARPE‐19 cells. Meanwhile, we observed that the expression of TGF‐ β 2, p‐AKT, and p‐GSK‐3 β was upregulated in H 2 O 2 ‐treated ARPE‐19 cells and downregulated in luteolin‐treated cells, revealing that luteolin inhibited the activation of the AKT/GSK‐3 β pathway. However, these effects of luteolin were all annulled by transfecting ARPE‐19 cells with Nrf2 siRNA. Our current data collectively indicated that inhibition of luteolin on EMT was induced by oxidative injury in ARPE‐19 cell through the Nrf2 and AKT/GSK‐3 β pathway, suggesting that luteolin could be a potential drug for the treatment of dry AMD.