The inflammatory accumulation of lipids and ROS in human Nrf1α-deficient hepatoma cells is ameliorated by 2-bromopalmitate

Abstract

AbstractSince Nrf1 and Nrf2 are essential for regulating the lipid metabolism pathways, their dysregulation was also shown to be critically involved in the non-controllable inflammatory pathology into cancer development. However, it is unknown that the interaction between Nrf1 and Nrf2 in the regulation of lipid metabolism, especially in hepatoma cells. Here, we have further explored the molecular mechanisms underlying their distinct regulation of lipid metabolism, by comparative analysis of changes in those lipid metabolism-related genes in Nrf1α-/- and/or Nrf2-/- cell lines relative to wild-type controls. The results revealed that loss of Nrf1 leads to disordered lipid metabolism; its lipid synthesis pathway was up-regulated by JNK-Nrf2-AP1 signaling, while its lipid decomposition pathway was down-regulated by the nuclear receptor PPAR-PGC1 signaling, resulting in severe accumulation of lipids as deposited in lipid droplets. By contrast, knockout of Nrf2 gave rise to decreases in lipid synthesis and uptake capacity. These demonstrate that Nrf1 and Nrf2 contribute to significant differences in the cellular lipid metabolism regulatory profiles and relevant pathological responses. Further experiments unraveled that lipid deposition in Nrf1α-/- cells was resulted from CD36 upregulation by activating the PI3K-AKT-mTOR pathway, leading to induction of the inflammatory response. Following treatment of Nrf1α-/- cells with 2-bromopaImitate (2BP), it enabled the yield of lipid droplets to be strikingly alleviated, as companied by substantial abolishment of CD36 and critical inflammatory cytokines. Such Nrf1α-/--led inflammatory accumulation of lipids and ROS was significantly ameliorated by 2BP. Overall, this study provides a potential strategy for cancer prevention and treatment by precision targeting of Nrf1, Nrf2, or both.