Developmental Toxicity Of Olaparib On Craniofacial Cartilage In Zebrafish

Anticancer drugs, classified as emerging contaminants, pose environmental risks due to improper disposal. Olaparib, a poly(ADP-ribose) polymerase (PARP) inhibitor widely used in oncology and autoimmune diseases. While epidemiological studies link olaparib to various adverse effects, its impact on craniofacial skeletal development remains unexplored. This study investigates olaparib-induced craniofacial cartilage toxicity in zebrafish and its molecular mechanisms, providing insights into human craniofacial malformations. Zebrafish embryos (0.5–120 hpf) were exposed to olaparib (0.05-0.15 μM). Craniofacial cartilage morphology was assessed via Alcian Blue staining, while oxidative stress and apoptosis were evaluated using ROS staining and TUNEL assay. RNA-Seq and qRT-PCR analyzed gene expression patterns. Co-exposure experiments with astaxanthin (an antioxidant) or C59 (Wnt inhibitor) were conducted to validate mechanistic pathways. Developmental window sensitivity was determined by staged exposures. Olaparib exposure impaired craniofacial cartilage morphology. Transient exposure did not induce malformations, whereas continuous exposure from 5–48 hpf caused severe craniofacial defects. qRT-PCR revealed dysregulation of genes critical for cranial neural crest cell (CNCC) proliferation and differentiation. RNA-Seq identified activation of oxidative stress and Wnt signaling pathways, which were partially rescued by astaxanthin or C59. Olaparib disrupts craniofacial cartilage development by inducing CNCC apoptosis and differentiation defects, with a sensitive window at 5–48 hpf. Mechanistically, oxidative stress, apoptosis, and Wnt pathway activation mediate this toxicity. These findings highlight olaparib’s environmental risks and provide a model for studying human craniofacial malformations. Further research is warranted to elucidate downstream molecular targets.