Mono-(2-ethylhexyl) phthalate impairs insulin secretion in rat insulinoma cells by inducing ferroptosis via oxidative stress.

Di(2-ethylhexyl) phthalate (DEHP), a frequently used plasticizer, is a prototypical endocrine-disrupting chemical. The mechanism by which DEHP affects glucose regulation and insulin resistance has not been fully elucidated. Mono-(2-ethylhexyl) phthalate (MEHP) is the principal DEHP metabolite. In this study, rat insulinoma (INS-1) cells were treated with MEHP at 30, 60, and 120 μM for 24 h. Compared to the 0 μM MEHP (control group), 30, 60, and 120 μM MEHP significantly lowered insulin secretion and raised intracellular Fe²⁺ levels in INS-1 cells, while reducing SOD and GSH levels and increasing ROS levels (all P < 0.05). MDA levels increased in the 60 and 120 μM MEHP groups (all P < 0.05). MEHP exposure disrupted iron metabolism and ferroptosis pathways, upregulating TFR1 mRNA and protein, downregulating FTH1 mRNA and protein, and increasing STEAP3 mRNA and protein expression. SLC7A11 and GPX4 mRNA and protein expression were significantly suppressed (all P < 0.05). Fer-1 (1 μM) effectively alleviated MEHP-induced cytotoxicity, restored GSIS capacity, reduced intracellular Fe²⁺ accumulation, ameliorated oxidative damage, and reactivated the SLC7A11/GPX4 signaling pathway in INS-1 cells (all P < 0.05). This study demonstrates that MEHP induces Fe2+ accumulation, oxidative stress, lipid peroxidation, and ferroptosis in INS-1 cells via the suppression of the SLC7A11/GPX4 signaling pathway, consequently impairing IS. Fer-1 alleviated these effects. These findings establish ferroptosis as a novel mechanism underlying DEHP/MEHP-induced β cell dysfunction and provide new insights into the role of PAEs, environmental pollutants, in diabetes pathogenesis.