Estrogenic Activity Assessment in Environmental Matrices by Means of In Vitro Cell‐Based Bioassays Coupled With Molecular Investigation

Abstract

Pollution of river systems in Tunisia by endocrine disrupting compounds (EDCs) is due to anthropogenic impacts through non‐treated industrial wastewater and municipal‐treated wastewater discharge. The aim of this study was to assess the estrogenic activity of environmental matrices involving raw industrial wastewater (WW), surface water (SW), and treated wastewater (TWW). A modified E‐screen assay was used to evaluate estrogenic activity of the samples in MCF‐7 breast cancer cells. Western blotting and real‐time PCR molecular approaches were applied to investigate the mechanism of EDC‐induced MCF‐7 breast cancer cell proliferation which interferes with estrogen receptor alpha (ERα) and c‐Jun. Our results revealed a dose‐dependent estrogenic activity reaching an optimal level at a concentration of 0.01% for industrial WW and SW and 10% for TWW. Monitoring ERα protein and c‐Jun gene expression levels after 1, 6, 24, and 48 h of treatment showed a correlation in the overexpression of ERα and c‐Jun most of the time. In fact, ERα and c‐Jun correlated up‐regulation began after 1 h of treatment for industrial WW, TWW, and one SW sample. For the other SW samples, this correlated up‐regulation started after 6–24 h of treatment. Results emphasized the estrogen‐like effect of our contaminated samples on MCF‐7 cells which facilitate a cross‐talk between ERα and c‐Jun factor, thereby directly regulating the expression of estrogen‐induced genes to mediate breast cancer cell growth.