Abstract
The number and amount of man-made chemicals present in the aquatic environment has increased considerably over the past 50 years. Among these contaminants, endocrine-disrupting chemicals (EDCs) represent a significant proportion. This family of compounds interferes with normal hormonal processes through multiple molecular pathways. They represent a potential risk for human and wildlife as they are suspected to be involved in the development of diseases including, but not limited to, reprotoxicity, metabolic disorders, and cancers. More precisely, several studies have suggested that the increase of breast cancers in industrialized countries is linked to exposure to EDCs, particularly estrogen-like compounds. Estrogen receptors alpha (ERα) and beta (ERβ) are the two main transducers of estrogen action and therefore important targets for these estrogen-like endocrine disrupters. More than 70% of human breast cancers are ERα-positive and estrogen-dependent, and their development and growth are not only influenced by endogenous estrogens but also likely by environmental estrogen-like endocrine disrupters. It is, therefore, of major importance to characterize the potential estrogenic activity from contaminated surface water and identify the molecules responsible for the hormonal effects. This information will help us understand how environmental contaminants can potentially impact the development of breast cancer and allow us to fix a maximal limit to the concentration of estrogen-like compounds that should be found in the environment. The aim of this review is to provide an overview of emerging estrogen-like compounds in the environment, sum up studies demonstrating their direct or indirect interactions with ERs, and link their presence to the development of breast cancer. Finally, we emphasize the use of in vitro and in vivo methods based on the zebrafish model to identify and characterize environmental estrogens.
Highlights
Breast cancer is the most commonly diagnosed cancer in women and is the second highest cause of death by cancer in women in Western countries
Triclosan induced morphological changes of the mammary gland by increasing adipose tissue and decreasing the proportion of lobular tissue, but further transcriptomic and gene set enrichment analysis showed that genes upregulated by triclosan treatment during that exposure were homologous to genes downregulated in breast cancer in humans; genes downregulated by triclosan are homologous to certain genes upregulated in breast cancer [68]. These results suggest that the model species, timing of exposure, and/or dose can have significantly different effects; further studies should be undertaken to better understand how triclosan can affect the development of breast cancer
In a reconstituted glial cell-based assay (U-250 MG), we showed that the estrogenic potency of environmental chemicals differed markedly depending on the zfER subtype expressed in the assay
Summary
Breast cancer is the most commonly diagnosed cancer in women and is the second highest cause of death by cancer in women in Western countries. About 50,000 cases of breast cancer are recorded each year in France and the Breast Cancer Society estimates over 250,000 new cases in the USA for. The incidence of hormone-dependent cancers has increased over the past 30 years in industrialized countries [1,2]. Age is one of the primary risk factors for the development of breast cancer, this increase is due to the aging of the population as it is observed in all age groups. Hormonal over-exposure, especially to the estrogen 17β estradiol (E2), is the major risk factor: early menarche and late menopause as well as hormone replacement therapies and
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