Cadmium Exposure Induces Apoptosis and Necrosis of Thyroid Cells via the Regulation of miR-494-3p/PTEN Axis

Cadmium (Cd) exposure is a persistent pollution problem, necessitating caution in using cadmium-expelling complexing agents. Currently, there is no targeted therapy to treat Cd poisoning. The thyroid gland is a major endocrine organ that directly regulates thyroid hormones involved in various physiological processes and is a target organ for Cd accumulation. Herein, the effects of Cd exposure on swine thyroid glands were investigated. Six-week-old male pigs were randomly divided into the Cd and control groups. The control group was fed a normal diet containing 0 mg Cd/kg, while the Cd group was fed a diet containing 20 mg Cd/kg (CdCl2) for 40 days. The regulation mechanism of phosphatase and tensin homolog (PTEN) microRNA-494-3p (miR-494-3p) was evaluated to determine the toxic effects of Cd exposure on free radicals' cleaner. Notably, heat shock proteins (HSPs) were triggered as defense agents against Cd. Cd exposure increased the enzyme activity of superoxide dismutase1(SOD1) and SOD2, catalase (CAT), and glutathione (GSH), and the endoplasmic reticulum stress in thyroid cells. Histopathological staining, RT-qPCR, and Western Blot assays were further employed to detect possible apoptosis and necroptosis of thyroid cells induced by Cd exposure. The assays revealed increased thyroid inflammatory injury, fibrosis, and apoptosis caused by Cd exposure. This study demonstrates the role of microRNAs in regulating Cd toxicity in pig thyroid tissue and provides evidence of Cd's negative effects. It further provides an assessment of the toxicological impact of Cd as an environmental endocrine disruptor (ED) that threatens public health and safety, which forms a basis for the development of Cd poisoning treatment therapies.