Cytotoxic effects of cadmium in mammary epithelial cells: Protective role of the macrocycle [15]pyN5

Human exposure to cadmium (Cd) occurs via different routes, including diet. The increasing amount of data linking Cd with different cellular effects in the mammary gland justifies additional toxicological assessments using human mammary epithelial cells. This work aimed therefore to assess the cytotoxic effects of Cd in MCF10A cells and to characterize the cytoprotective role of the macrocycle [15]pyN(5) in the form of calcium salt. Cadmium chloride revealed to be cytotoxic to MCF10A cells, decreasing cell viability and proliferation in a concentration-dependent manner. Comparable dose-response curves and IC50 values (57-63 mu M, 24 h treatment) were obtained using the MTT reduction, crystal violet and BrdU assays. In terms of reactive oxygen species formation, only a slight increase in superoxide radical anion was observed at very high Cd concentrations ( >= 100 mu M). Chelation should thus constitute the primary strategy to mitigate the cytotoxic effects induced by Cd in mammary cells. In this context, [15]pyN(5) which presents appropriate chemical and thermodynamic features was studied as a Cd chelator. This macrocycle (25 and 50 mu M) significantly reduced or even abolished Cd-induced cytotoxicity. Protective effects were observed in terms of cell viability, cell proliferation and morphological alterations, being the protection mostly attributed to a chelating-based mechanism. (C) 2012 Elsevier Ltd. All rights reserved.