Abstract
The MCF-7 human breast cancer cell line has been widely used in studies in the fields of cancer biology, steroid hormone biochemistry and toxicology. MCF-7 cells were demonstrated to be enhanced cell proliferation by estrogens. The estrogen-dependent growth of MCF-7 cells is often called E-Screen, which is one of the most sensitive assays for estrogenicity assessment. On the contrary, there is a potential for this assay to identify false positives by cell mitogens and false negatives by cytotoxic or general growth inhibitors. Therefore, when we subject environmental samples to an E-screen test, we have to examine the interaction of contaminant substances in the cells. In this study, we evaluated the endocrine-disrupting activity of multiply contaminated model samples using the E-screen test. Through this study, we demonstrated that some chemicals prevent the estrogenicity of endocrine-disrupting chemicals, and furthermore, this estrogenicity is induced by other chemicals. This result indicates that the fractionation of chemicals in environmental samples is essential for evaluating their estrogenicity using a bioassay technique.
