Cadmium induced Fak-mediated anoikis activation in kidney via nuclear receptors (AHR/CAR/PXR)-mediated xenobiotic detoxification pathway

Cadmium (Cd) is a toxic heavy metal of considerable toxicity, possessing a serious environmental problem that threatening food safety and human health. However, the underlying mechanisms of Cd-induced nephrotoxicity and detoxification response remain largely unclear. Cd was administered at doses of 35, 70, and 140 mg/kg diet with feed for 90 days and produced potential damage to chickens' kidneys. The results showed that Cd exposure induced renal anatomical and histopathological injuries. Cd exposure up-regulated cytochrome P450 enzymes (CYP450s), activated nuclear xenobiotic receptors (NXRs) response, including aryl hydro-carbon receptor (AHR), constitutive androstane receptor (CAR), and pregnane X receptor (PXR) by low and moderate doses of Cd, and induced an increase in CYP isoforms expression. Cd exposure down-regulated phase II detoxification enzymes (glutathione-S-transferase (GST), glutathione peroxidase (GSH-PX) activities, and glutathione (GSH) content), and GST isoforms transcription. Furthermore, ATP-binding cassette (ABC) transporters, multidrug resistance protein (MRP1), and P-glycoprotein (P-GP) levels were elevated by low dose, but high dose inhibited the P-GP expression. Activation of detoxification enzymes lost their ability of resistance as increasing dose of Cd, afterwards brought into severe renal injury. Additionally, Cd suppressed focal adhesion kinase (Fak) and integrins protein expression as well as activated extrinsic pathway and intrinsic pathways, thereby producing anoikis. In conclusion, these results indicated that Cd induced Fak-mediated anoikis activation in the kidney via nuclear receptors (AHR/CAR/PXR)-mediated xenobiotic detoxification pathway.