First evidence of estrogenic potential of the cyanobacterial heptotoxins the nodularin-R and the microcystin-LR in cultured mammalian cells.
The estrogenic activity of cyanobacterial hepatotoxins microcystin-LR (MC-LR) and nodularin-R (NOD-R) was for the first time investigated invitro in a stably transfect cell line with an estrogen-regulated luciferase gene. Treatment of cells with NOD-R caused a dose-dependent increase in the luciferase activity. NOD-R gave rise to an induction of luciferase activity with an EC(50) value of 66.4 nM, whereas the positive control, 17beta-estradiol (E2) had an EC(50) of 9.6 pM. This indicates that NOD-R is a 6900-fold weaker inducer of luciferase than E2. In contrast, only a slight but significant activation of the luciferase gene was observed with MC-LR between 2.01 and 60.1 nM, and a maximal-induced response was observed with 10.1 nM, approximately 25% of the maximal effect obtained with 1 nM E2. The decrease in the luciferase activity at high MC-LR concentrations can be explained by a cytotoxic effect. No synergistic estrogenic effect was observed when each toxin was co-administrated with E2. However, the induction of the luciferase activity by NOD-R and MC-LR was inhibited by co-treatment with 1 microM of the pure estrogenic receptor (ER) antagonist ICI 182,780, thus proving the ER-dependency of the estrogenic effect.
Oziol
Lucie
L
Laboratoire Ecologie, Systématique et Evolution (UMR 8079), Université Paris-Sud 11, Bâtiment 362, 91405 Orsay Cedex, France.
Bouaïcha
Noureddine
N
D045744:Cell Line, Tumor; D000458:Cyanobacteria / Q000737:chemistry*; D004958:Estradiol / Q000494:pharmacology*; D006801:Humans; D008387:Marine Toxins; D052998:Microcystins / Q000494:pharmacology*; D010456:Peptides, Cyclic / Q000494:pharmacology*; D015203:Reproducibility of Results
D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; C063998:nodularin; D004958:Estradiol; C057862:cyanoginosin LR