Olaparib induces craniofacial cartilage malformations in zebrafish embryos through DNA damage, oxidative stress, and Wnt dysregulation.

Pharmaceutical residues in aquatic environments are a growing concern. Global surveillance has detected these residues in nearly a quarter of the world's rivers, with anticancer drugs drawing particular attention due to their high bioactivity. Olaparib (Ola), a poly(ADP-ribose) polymerase (PARP) inhibitor, is widely used to treat breast and ovarian cancers, but its developmental toxicity to aquatic vertebrates remains unclear. We exposed zebrafish embryos to Ola (5-15 mg/L) from 6 to 120 h post-fertilization (hpf). Ola exposure caused dose-dependent craniofacial cartilage malformations and behavioral abnormalities. Mechanistically, Ola induced DNA damage (Comet assay) and mitochondrial depolarization (JC-10), as well as oxidative stress evidenced by elevated reactive oxygen species (ROS) levels and impaired antioxidant defenses. Ola exposure impaired cranial neural crest cell (CNCC) migration, as shown by reduced sox10:GFP⁺ fluorescence and altered expression of pax3a, dlx2a, and dlx5a. It also reduced chondrogenic differentiation, with lower expression of sox9a and col2a1, and increased apoptosis, as indicated by more TUNEL-positive cells. Ola also altered Wnt/β‑catenin pathway gene expression. Pharmacological rescue experiments showed that the antioxidant astaxanthin (60 μg/L) and the Wnt inhibitor C59 (3.79 μg/L) both attenuated craniofacial malformations. Together, these results indicate that Ola induces DNA damage and oxidative stress, impairs CNCC function, and disrupts Wnt signaling, leading to craniofacial cartilage deformities. This study underscores the developmental toxicity of PARP inhibitors as emerging environmental contaminants and offers insights into the mechanisms underlying craniofacial cartilage malformations.