Validation of two in vitro test systems for estrogenic activities with zearalenone, phytoestrogens and cereal...

In order to establish alternatives to the frequently used uterotropic assay with mice, defined estrogen-sensitive cell lines (MCF-7 cells and LeC-9 cells) were used to determine the estrogenic activities of purified compounds of vegetable origin (myco- and phytoestrogens) and zearalenone-contaminated forage cereals (wheat, barley and oats). In MCF-7 cells, a human breast cancer cell line, the induction of an estrogen-specific exoprotein served as a parameter of estrogenic activities. LeC-9 cells represent a genetically transformed cell clone derived from mouse L-cells. Here, hormone-like activities were measured by the expression of the bacterial chloramphenicol acetyltransferase (CAT) gene under the control of an estrogen-responsive element. Toxic effects affecting cell viability were monitored in this system by the expression of a second reporter gene (the bacterial beta-galactosidase gene controlled by the constitutive human beta-actin promoter). Relative estrogenic activities of myco- and phytoestrogens determined with both systems are concomitant, but higher as compared to the uterotropic assay with mice.