Curcumin and (−)- Epigallocatechin-3-Gallate Protect Murine MIN6 Pancreatic Beta-Cells against Iron Toxicity and Erastin-Induced Ferroptosis

Abstract

Ferroptosis is a form of programmed cell death that is characterized by lipid peroxidation and is inducible by iron and the accumulation of reactive oxygen species (ROS). It is triggered by erastin but inhibited by antioxidants such as -tocopherol, -carotene, polyphenols, and iron chelators such as deferoxamine (DFO), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA). This study investigated the protective effects of two polyphenols, curcumin and (−)- epigallocatechin-3-gallate (EGCG), against iron loading and erastin-mediated ferroptosis in MIN6 cells. Cells were treated with polyphenols before exposure to iron-induced oxidative stress comprising of 20 μmol/L of 8-hydroxyquinoline (8HQ) and 50 μmol/L of ferric ammonium citrate, (FAC) (8HQ+FAC) or Fenton reaction substrate (FS) (30 μmol/L of FeSO4 and 0.5 of mmol/L H2O2) and 20 μmol/L erastin. Cell viability was determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay, iron levels were measured by inductively-coupled plasma mass spectrometry (ICP-MS), glutathione and lipid peroxidation were assayed with commercially-available kits. Curcumin and EGCG both significantly protected pancreatic cells against iron-induced oxidative damage. Moreover, both compounds also protected against erastin-induced ferroptosis in pancreatic cells. The polyphenols enhanced cell viability in erastin-treated MIN6 cells in a dose- and time-dependent manner. Furthermore, MIN6 cells exposed to erastin alone showed elevated levels of iron, glutathione (GSH) depletion, glutathione peroxidase 4 (GPX4) degradation and lipid peroxidation (p < 0.05) compared to cells that were protected by pre-treatment with curcumin or EGCG. Taken together, the data identify curcumin and EGCG as novel ferroptosis inhibitors, which might exert their protective effects by acting as iron chelators and preventing GSH depletion, GPX4 inactivation, and lipid peroxidation in MIN6 cells. The implications of the findings on the effects of iron overload and ferroptosis represent a potential therapeutic strategy against iron-related diseases.

Oxidative stress in alpha and beta cells as a selection criterion for biocompatible biomaterials

“…This study showed that MIN6 cells alone could adapt to oxidative stress through an increased expression of the endogenous antioxidant heme oxygenase-1, a mechanism that was previously shown to decrease in intracellular oxidative stress [56].…”

Antidiabetic Properties of Curcumin I: Evidence from In Vitro Studies

“…In a study by Kose et al (2019), pre-treatment of MIN6 cells with curcumin (20 µM) for 24 h resulted in reduced ferroptosis, programmed cell death induced by lipid peroxidation [116]. Curcumin treatment increased erastin-induced cell viability dose-and time-dependently.…”

“…Curcumin treatment increased erastin-induced cell viability dose-and time-dependently. In addition, iron levels, glutathione peroxidase 4 (GPX4) and lipid peroxidation were reduced, while glutathione levels were increased with curcumin treatment (Table 4) [116].…”

“…In addition, peroxynitrite, NO and activated PARP levels were reduced with curcumin treatment, suggesting increased cytoprotection (Table 4) [105]. [116] An alternative treatment to T1DM than the conventional exogenous insulin injection is pancreatic islet transplantation. However, this procedure is limited by islet cryopreservation and recovery during the thawing process [117].…”

Quercetin Alleviates Ferroptosis of Pancreatic β Cells in Type 2 Diabetes

“…Serving as a naturally occurring inhibitor or regulator of iron metabolism, quercetin is beneficial on iron overload related diseases. Furthermore, recent studies showed that polyphenols, including quercetin, curcumin, and epigallocatechin-3-gallate may present as a potent inhibitor of ferroptosis but not apoptosis [ 22 , 23 ]. However, up to now, the potential anti-diabetic role of quercetin on PBC ferroptosis has not been explored.…”