Oxidant generation promotes iron sequestration in BEAS-2B cells exposed to asbestos.

Lung injury after asbestos exposure is associated with an oxidative stress that is catalyzed by iron in the fiber matrix, complexed to the surface, or both. We tested the hypothesis that the cellular response to asbestos includes the transport and sequestration of this iron through (1) generation of superoxide for ferrireduction, (2) up-regulation of divalent metal transporter-1 (DMT1) for intracellular transport of Fe2+, and (3) increased production of cellular ferritin where the metal is stored in a catalytically less reactive state. BEAS-2B cells with normal and elevated Cu,Zn superoxide dismutase (SOD) expression were employed for in vitro investigations. After exposure of these cells to asbestos, we demonstrated by fluorescence methodology a significantly increased generation of SOD with ferrireductive capacity. Fiber exposure also increased DMT1 protein and mRNA expression in the BEAS-2B cells. Incubation with asbestos elevated cellular iron and ferritin concentrations, and these responses were dimi...