Lead Inhibits Growth and Induces Apoptosis in Normal Rat Fibroblasts
Ivo Iavicoli, Giovanni Carelli, Alessandro Sgambato, Oliviero Masci, Raffaele Ardito, Achille Cittadini and Nicolò Castellino
The effects on normal rat fibroblasts of lead supplementation (as lead acetate) in the medium were examined. The amount of lead acetate ranged from 0.078µM to 320µM, at 14 concentrations. The normal level of lead in the medium was 0.060µM, and the normal concentration of lead in the fibroblasts was 3.1 ± 0.1ng/107 cells: these represented the control conditions. On studying fibroblast proliferation and survival after incubation for 48 hours, a lead acetate dose-dependent inhibition of cell proliferation was observed, the results being shown to be significant by ANOVA (p < 0.01), and suggesting a significant dose–response relationship. Apoptosis, evaluated by quantifying cytoplasmic DNA fragments, differed significantly among the lead levels tested. The distribution in the cell cycle, evaluated by using a fluorescence-activated cell sorter, showed a dose-dependent accumulation of cells in the G0/G1 phase, with a compensatory decrease in the percentage of cells in the S phase. Moreover, the occurrence of a subdiploid peak confirmed that apoptosis was more evident when the medium was supplemented with lead acetate at concentrations of 5–20µM. The inhibition of cell growth is probably due to a direct inhibition of cell proliferation.