RNAi-mediated ablation of Nrf2 in PyMT-1099 LT, Py2T LT and MT∆Ecad mesenchymal breast cancer cells

Background: Epithelial-mesenchymal transition (EMT) has been implicated in metastasis, drug resistance, survival under stress and also conferring stem cell-like traits to cancer cells. We have aimed at exploring the crosstalk between ROS and an EMT induced by TGFb in breast cancer cells. Methods: We observed that cells exposed to TGFb displayed a decrease of ROS levels. Furthermore, we identified an activation of the Nrf2 transcription factor, master regulator of the antioxidant response in TGFb-induced mesenchymal cells. In order to know the effect of Nrf2 ablation in epithelial and mesenchymal cells, RNAi-mediated ablation for Nrf2 was performed. Results: RNAi-mediated ablation of Nrf2 led to mesenchymal cancer cell death due to ferroptosis, an iron- and oxidative stress-dependent cell death. Moreover, analysis revealed that several glutathione pathway genes were specifically regulated by Nrf2, suggesting a role of glutathione-related pathways in mesenchymal cell survival. Conclusion: In this study we report the criticial role of the Nrf2-mediated glutathione metabolism in the protection of metastatic breast cancer cells from ferroptosis. Therapeutic targeting of antioxidant pathways may thus be beneficial for patients with metastatic disease. RNA-Seq of Py2T-1099 LT, Py2T LT and MT∆Ecad mesenchymal cells after RNAi-mediated ablation of Nrf2 performed in biological duplicates