Curcumin mitigates palmitic acid-induced senescence in MIN6 β cells through NOX4/ROS regulation

Pancreatic β cell senescence is a key driver of type 2 diabetes (T2D) progression, and oxidative stress plays a critical role in this process. This study explored the therapeutic potential of curcumin against palmitic acid (PA)-induced senescence in MIN6 cells. We also explored whether this protection was achieved via modulation of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4)/reactive oxygen species (ROS) pathway.

We used PA to establish a lipotoxicity model in MIN6 cells. We assessed cell viability by Cell Counting Kit-8 (CCK-8) assay and insulin secretion with glucose-stimulated insulin secretion (GSIS) assay. We used flow cytometry to measure calcium concentration, β-galactosidase activity, cell cycle distribution, ROS production and mitochondrial membrane potential. Western blot was used to analyze the expression of NOX4 and senescence markers p16 and p21. We also performed molecular docking to predict the binding mode between curcumin and NOX4. We knocked down NOX4 to confirm its role in curcumin's protective effects.

PA significantly reduced MIN6 cell viability, insulin secretion and intracellular calcium concentration. PA induced cellular senescence, as evidenced by increased β-galactosidase activity, upregulated p16 and p21 expression and cell cycle arrest in the G0/G1 phase. PA activated the NOX4/ROS pathway, leading to ROS overproduction and a decrease in mitochondrial membrane potential. Curcumin treatment partially reversed these effects. Molecular docking showed curcumin binds strongly to NOX4 (binding energy: -8.4 kcal/mol). NOX4 knockdown enhanced curcumin's effects on oxidative stress and cell senescence.

Curcumin mitigates PA-induced senescence in MIN6 cells and restores insulin secretion by inhibiting the overactivation of the NOX4/ROS pathway and reducing oxidative stress.