Downregulation of placental SI OOP is associated with cadmium exposure in Guiyu, an e-waste recycling town in China

摘要

Excessive release of heavy metals, especially cadmium (Cd) and lead (Pb), results from primitive electronic waste (e-waste) recycling activities in Guiyu, China, and has adverse effects on the health of local infants and pregnant women. We investigated the expression of placental SI OOP, a Ca~(2+)-binding protein, as a biological indicator of heavy-metal environmental pollution in pregnant women involved in these activities and constantly exposed to Cd and Pb. We included 105 pregnant women in the study: 55 from Guiyu and 50 from Shantou, an area not involved in e-waste recycling. The placental concentrations of Cd and Pb (PCCd, PCPb) after birth were measured by graphite-furnace atomic-absorption spectrometry. SI OOP mRNA expression was determined by semi-quantitative RT-PCR and real-time quantitative PCR. SI OOP protein expression was examined by western blot analysis and immunohistochemistry. The expression of metallothionein (MT), previously found upregulated after heavy metal contamination, was used for comparison. Placentas from Guiyu women showed 62.8% higher Cd concentrations, higher MT levels, and lower SI OOP protein levels than placentas from Shantou women. Furthermore, PCCd was negatively correlated with SI OOP protein expression and positively with MT expression, with no correlation between PCPb and SI OOP or MT expression. The PCCd-associated downregulation of SI OOP in placentas from Guiyu women suggests that SI OOP might be an effective biological indicator in the placental response to Cd toxicity in areas of e-waste recycling.