Mechanistic insights into TDCPP-induced DNA damage in GT1-7 cells

As a typical organophosphate ester compound, tris(1,3-dichloro-2-propyl) phosphate (TDCPP) exhibits both estrogenic activity and genotoxicity. However, the involvement of estrogen signaling pathways in TDCPP-induced genotoxicity remains unclear. This study evaluated the effects of TDCPP (0.001-200 μM) on DNA damage and repair-related endpoints in GT1-7 mouse hypothalamic cells, and examined the roles of estrogen nuclear receptors (ERα/β) and G protein-coupled estrogen membrane receptor 1 (GPER1), as well as their downstream ERK1/2 and AKT signaling pathways, in TDCPP-induced DNA damage. Our results showed that TDCPP exposure elevated intracellular levels of reactive oxygen species (ROS) and malondialdehyde (MDA), induced DNA damage and G2/M cell cycle arrest, and increased mitochondrial damage and micronucleus formation. In addition, TDCPP significantly increased the protein expression of ATM and γ-H2AX, key markers of DNA double-strand breaks (DSBs), and upregulated the mRNA expression of most DSB repair-related genes, while downregulated mRNA expression of most DNA single-strand break (SSB) repair-related genes. TDCPP also upregulated both protein and gene expression of GPER1 and enhanced ERK1/2 phosphorylation. Pretreatment with the GPER1 inhibitor G15 or the ERK1/2 inhibitor U0126 significantly suppressed TDCPP-induced upregulation of ATM and γ-H2AX protein expression, reversed changes in mRNA levels of DSB/SSB repair-related genes, and reduced TDCPP-induced DNA damage in GT1-7 cells. These findings indicate that TDCPP activates the GPER1-ERK1/2 signaling pathway, which plays a critical role in mediating its DNA-damaging effects. CAPSULE: TDCPP induced DNA damage in GT1-7 cells by activating GPER1-ERK1/2 signaling pathway.