TIGAR Protects Against Adenine-Induced Ferroptosis in Human Proximal Tubular Epithelial Cells by Activating the mTOR/S6KP70 Axis

Nutr Cancer. 2023;75(6):1464-1472. doi: 10.1080/01635581.2023.2203353. Epub 2023 May 4.

Abstract

TP53-induced glycolysis and apoptosis regulator (TIGAR) acts as a switch for nephropathy, but its underlying mechanism is still unclear. The purpose of this study was to explore the potential biological significance and underlying mechanism of TIGAR in modulating adenine-induced ferroptosis in human proximal tubular epithelial (HK-2) cells. HK-2 cells under- or overexpressing TIGAR were challenged with adenine to induce ferroptosis. The levels of reactive oxygen species (ROS), iron, malondialdehyde (MDA), and glutathione (GSH) were assayed. Expression of ferroptosis-associated solute carrier family seven-member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) at the level of mRNA and protein were measured by quantitative real-time-PCR and western blotting. The phosphorylation levels of proteins in the mTOR/S6KP70 pathway were determined by western blotting. Adenine overload triggered ferroptosis in HK-2 cells, as evidenced by reduced levels of GSH, SLC7A11, and GPX4, and increased levels of iron, MDA, and ROS. TIGAR overexpression repressed adenine-induced ferroptosis and induced mTOR/S6KP70 signaling. Inhibitors of mTOR and S6KP70 weakened the ability of TIGAR to inhibit adenine-induced ferroptosis. TIGAR inhibits adenine-induced ferroptosis in human proximal tubular epithelial cells by activating the mTOR/S6KP70 signaling pathway. Therefore, activating the TIGAR/mTOR/S6KP70 axis may be a treatment for crystal nephropathies.

MeSH terms

  • Adenine / pharmacology
  • Apoptosis
  • Apoptosis Regulatory Proteins / metabolism
  • Epithelial Cells / metabolism
  • Ferroptosis*
  • Glutathione / metabolism
  • Glycolysis
  • Humans
  • Iron
  • Phosphoric Monoester Hydrolases / metabolism
  • Reactive Oxygen Species / metabolism
  • TOR Serine-Threonine Kinases / metabolism

Substances

  • Reactive Oxygen Species
  • Adenine
  • Phosphoric Monoester Hydrolases
  • Apoptosis Regulatory Proteins
  • TOR Serine-Threonine Kinases
  • Glutathione
  • Iron