In Vitro Evaluation of the Effects of Zearalenone and α-Zearalenol on MCF-7 and MDA-MB-468 Cell Lines of Human Breast Cancer

Toxicity of zearalenone and its nutritional intervention by natural products

Zearalenone (ZEN) is a toxic secondary metabolite mainly produced by fungi of the genus Fusarium, and is often present in various food and feed ingredients such as corn and wheat. The structure of ZEN is similar to that of natural estrogen, and it can bind to estrogen receptors and has estrogenic activity. Therefore, it can cause endocrine-disrupting effects and promote the proliferation of estrogen receptor-positive cell lines. In addition, ZEN can cause oxidative damage, endoplasmic reticulum stress, apoptosis, and other hazards, resulting in systemic toxic effects, including reproductive toxicity, hepatotoxicity, and immunotoxicity. In the past few decades, researchers have tried many ways to remove ZEN from food and feed, but it is still a challenge to eliminate it. In recent years, natural compounds have become of interest for their excellent protective effects on human health from food contaminants. Researchers have discovered that natural compounds often used as dietary supplements can effectively alleviate ZEN-induced systemic toxic effects. Most of the compounds mitigate ZEN-induced toxicity through antioxidant effects. In this article, the contamination of food and feed by ZEN and the various toxic effects and mechanisms of ZEN are reviewed, as well as the mitigation effects of natural compounds on ZEN-induced toxicity.

Effects of α-zearalenol on the metabolome of two breast cancer cell lines by 1H-NMR approach

INTRODUCTION

Zearalenone (ZEN) is one of the most widely distributed toxins that contaminates many crops and foods. Its major metabolites are α-Zearalenol (α-zol) and β-Zearalenol. Previous studies showed that ZEN and α-zol have estrogenic properties and are able to induce growth promoting effect in breast tissues.

OBJECTIVIES

Considering that tumorigenesis is dependent on the reprogramming of cellular metabolism and that the evaluation of the cellular metabolome is useful to understand the metabolic changes that can occur during the cancer development and progression or after treatments, aim of our work is to study, for the first time, the effects of α-zol on the metabolomic profile of an estrogen positive breast cancer cell line, MCF-7, and of an estrogen negative breast cancer cell lines MDA-MB231.

METHODS

Firstly, we tested the effects of α-zol on the cell viability after 24, 48 and 72 h of treatments with 10^-10, 10^-8 and 10^-6 M concentrations on breast cancer MCF-7 and MDA-MB231 cell lines in comparison to human non-cancerous breast MCF10A cell line. Then, we evaluated cell cycle progression, levels of reactive oxygen species (ROS) and the metabolomic profiling by ¹H-NMR approach on MCF-7 and MDA-MB231 before and after 72 h treatments. Principal component analysis was used to compare the obtained spectra.

RESULTS

α-zol is resulted able to induce: (i) an increase of the cell viability on MCF-7 cells mainly after 72 h treatment, (ii) a slight decrease of the cell viability on MDA-MB231 cells, and (iii) an increase of cells in S phase of the cell cycle and of ROS only in MCF-7 cells. Moreover, the evaluation of metabolomics profile evidenced that after treatment with α-zol the levels of some metabolites increased in MCF-7 cells whereas decreased slightly in MDA-MB231 cells.

CONCLUSIONS

Our results showed that α-zol was able to increase the protein biosynthesis as well as the lipid metabolism in MCF-7 cells, and, hence, to induce an estrogen positive breast cancer progression.

Combined low-dose zearalenone and aflatoxin B1 on cell growth and cell-cycle progression in breast cancer MCF-7 cells

Zearalenone (ZEA) has long been recognized as a xenoestrogen, while the endocrine disrupting effects of aflatoxin B1 (AFB1) have been identified recently. Due to co-occurrence and endocrine disrupting potentials of ZEA and AFB1, it was hypothesized that co-exposure to ZEA and AFB1 might affect breast cancer cell growth. Consequently, the aim of this study was to evaluate the combined effects of ZEA and AFB1 (1nM-100nM) on cell growth and cell cycle progression, using a human breast cancer cell line MCF-7. Our results showed that ZEA and AFB1 produced significant interactive effects on cell growth, DNA synthesis and cell cycle progression. While ZEA promoted growth, DNA synthesis and cell cycle progression, AFB1 was cytotoxic and counteracted the effects of ZEA. ZEA altered the expression of several breast cancer related genes, whereas AFB1 had minimal effects on gene expression. With the use of specific inhibitors, ERα, GPER and MAPK pathways were found to be responsible for ZEA's effects on cell growth; while MAPK pathways might be involved in cytotoxic effects by AFB1. This study is first to report the effects of co-exposure of ZEA and AFB1 on breast cancer cell growth, possibly through ER dependent pathway. This suggested that endocrine-disrupting mycotoxins that co-occur in human food can interact and influence human health. Future work on interactive effects of endocrine-disrupting mycotoxins or other xenoestrogens is warranted, which will contribute to improved risk assessments.