Nucleolin Knockdown Enhances Cadmium Cytotoxicity in Cultured Vascular Endothelial Cells

Exposure to cadmium, an environmental pollutant, has been associated with adverse health effects such as atherosclerosis. Nucleolin is a multifunctional protein present in the nucleus, cytoplasm, and cell surface and involved in the angiogenesis and repair of the vascular endothelium following injury. Nucleolin dysfunction has been suggested to cause the development of vascular lesions. In the present study, we assessed the effect of cadmium on nucleolin expression in cultured bovine aortic vascular endothelial cells. After incubation with cadmium (0–5 µM), cellular NCL (nucleolin) mRNA levels and nucleolin protein levels were determined by real-time RT-PCR and western blotting, respectively. Cadmium did not alter nucleolin levels in vascular endothelial cells. We then evaluated whether nucleolin modulates endothelial cadmium-induced cytotoxicity by lactate dehydrogenase leakage. In nucleolin-knockdown vascular endothelial cells, cadmium-induced cytotoxicity was significantly higher than in control cells. Furthermore, nucleolin knockdown did not decrease the mRNA levels of metallothionein 1A and 2A, suggesting that nucleolin protects vascular endothelial cells against cadmium-induced cytotoxicity via metallothionein-independent pathways.