Ferroptosis may be an important mechanism of high glucose and high fat-induced pancreatic β cell death. This study investigated the effect and mechanism of grape seed procyanidin extract (GSPE) on ferroptosis in pancreatic β cells induced by high glucose and high fat.

An islet β cell injury model was established by treating MIN6 cells with 25 mmol/L glucose and 200 μmol/L sodium palmitate. Then, the cells were transfected with nuclear factor erythroid 2-related factor 2 small-interfering RNA (Nrf2 siRNA) and treated with 10, 20, 30, 40, 50, 75 and 100 mg/L GSPE. The cell activity was detected by the cell counting kit-8 (CCK8) assay, and the levels of intracellular glutathione (GSH), malonaldehyde (MDA) and reactive oxygen species (ROS) were detected by commercial kits. The protein expressionof Nrf2, heme oxygenase-1 (HO-1), NADPH: quinone oxidoreductase-1 (NQO1), iron metabolism indicator transferrin receptor 1 (TfR1), divalent metal transporter 1 (DMT1), ferritin, solute carrier family 7 member 11 (SLC7A11), glutathione peroxidase 4 (GPX4) and acyl-CoA synthetase long-chain family member 4 (ACSL4) were measured by Western blot.

Compared with the control group, high glucose and high fat caused intracellular iron deposition, up-regulated the protein expression levels of TfR1, DMT1 and ferritin, increased the levels of MDA, ROS and ACSL4, decreased the level of GSH and down-regulated the protein expression levels of GPX4 and SLC7A11. Intervention with GSPE could activate the Nrf2 signaling pathway to up-regulate GPX4 and SLC7A11 protein expression and increase the level of GSH. GSPE could also decrease the levels of MDA, ROS and ACSL4 and iron metabolism indices (TfR1, DMT1 and ferritin protein expression), thereby preventing ferroptosis in MIN6 cells induced by high glucose and high fat. After inhibition of the Nrf2 signaling pathway by Nrf2-siRNA transfection, the protective effect of GSPE was inhibited and the expression of the antioxidant enzymes HO-1, GPX4 and SLC7A11 was decreased.

GSPE reduces ferroptosis induced by high glucose and high fat possibly by activating the Nrf2 signaling pathway and up-regulating antioxidant enzymes, consequently improving the cell viability of MIN6 cells.

To investigate the effect of resveratrol (RSV) in increasing the sensitivity of pancreatic cancer cells to cisplatin (DDP) through inhibition of dihydroorotatede hydrogenase (DHODH) and to analyze its potential mechanism of action from the perspective of ferroptosis.

The human pancreatic ductal cancer cell line PANC1 (0, 10, 20, 30, 40, 50, 60, 70, and 80 μmol/L) and the human orthotopic pancreatic cancer cell line BxPC-3 (0, 2, 4, 6, 8, 10, 12, and 14 μmol/L) were treated with different doses of DDP to induce ferroptosis. Subsequently, the effect of intervention with brequinar (BQR) or RSV was explored on DDP-induced ferroptosis in pancreatic cancer cells. To explore the effects of DDP combined with BQR or RSV on ferroptosis-related intracellular molecules, cell viability was determined by the cell counting kit-8 (CCK-8) assay, and Western blot was used to detect the expression levels of glutathione peroxidase 4 (GPX4), recombinant solute carrier family 7 member 11 (SLC7A11 or xCT) and DHODH in cells. The content of malondialdehyde (MDA) was determined spectrophotometrically to evaluate the degree of lipid peroxidation. The level of intracellular reactive oxygen species (ROS) was detected using DCFH-DA probe to further understand the changes of oxidative stress. The fluorescent probe JC-1 was used to detect mitochondrial membrane potential (MMP) to explore the changes of mitochondrial function in cells. Immunofluorescence was used to detect the level of the cell proliferation marker Ki-67 to evaluate the changes of cell proliferation.

DDP treatment induced ferroptosis in pancreatic cancer cells (P＜0.05). Both BQR and RSV alone or in combination with DDP significantly decreased the protein expression levels of GPX4, xCT, and DHODH in pancreatic cancer cells (P＜0.05), as well as the levels of MMP and Ki-67 (P＜0.05). In contrast, BQR/RSV treatment elevated the levels of intracellular ROS and MDA (P＜0.05), and the effect was more pronounced in combination with DDP (P＜0.05). Transfection with DHODH adenovirus significantly reversed the inhibitory effect of DDP combined with RSV on the proliferation of pancreatic cancer cells (P＜0.05).

DHODH expression is up-regulated in pancreatic cancer tissues. DHODH inhibition promotes ferroptosis and enhances cisplatin sensitivity in pancreatic cancer cells. RSV may act as an inhibitor of DHODH to promote cisplatin-induced ferroptosis in pancreatic cancer cells.