Curcumin suppresses JNK pathway to attenuate BPA-induced insulin resistance in LO2 cells

Objective: To examine whether curcumin has protective effect on insulin resistance induced by bisphenol A (BPA) in LO2 cells and whether this effect was mediated by inhibiting the inflammatory mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-kappa B) pathways. Methods: LO2 cells were stimulated with BPA in the presence or absence of curcumin for 5 days. Glucose consumption, activation of insulin signaling, MAPKs and NF-kappa B pathways, levels of inflammatory cytokines and MDA production were analyzed. Results: Curcumin prevented BPA-induced reduction of glucose consumption and suppression of insulin signaling pathway, indicating curcumin alleviated BPA-triggered insulin resistance in LO2 cells. mRNA and proteins levels of TNF-alpha and IL-6, as well as MDA level in LO2 cells treated with BPA were decreased by curcumin. Furthermore, curcumin downregulated the activation of p38, JNK, and NF-kappa B pathways upon stimulation with BPA. Inhibition of JNK pathway, but not p38 nor NF-kappa B pathway, improved glucose consumption and insulin signaling in BPA-treated LO2 cells. Conclusion: Curcumin inhibits BPA-induced insulin resistance by suppressing JNK pathway.