Deciphering the Molecular Mechanisms Sustaining the Estrogenic Activity of the Two Major Dietary Compounds Zearalenone and Apigenin in ER-Positive Breast Cancer Cell Lines.

The flavone apigenin and the mycotoxin zearalenone are two major compounds found in the human diet which bind estrogen receptors (ERs), and therefore influence ER activity. However, the underlying mechanisms are not well known. To unravel the molecular mechanisms that could explain the differential effect of zearalenone and apigenin on ER-positive breast cancer cell proliferation, gene-reporter assays, chromatin immunoprecipitation (ChIP) experiments, proliferation assays and transcriptomic analysis were performed. We found that zearalenone and apigenin transactivated ERs and promoted the expression of estradiol (E2)-responsive genes. However, zearalenone clearly enhanced cellular proliferation, while apigenin appeared to be antiestrogenic in the presence of E2 in both ER-positive breast cancer cell lines, MCF-7 and T47D. The transcriptomic analysis showed that both compounds regulate gene expression in the same way, but with differences in intensity. Two major sets of genes were identified; one set was linked to the cell cycle and the other set was linked to stress response and growth arrest. Our results show that the transcription dynamics in gene regulation induced by apigenin were somehow different with zearalenone and E2 and may explain the differential effect of these compounds on the phenotype of the breast cancer cell. Together, our results confirmed the potential health benefit effect of apigenin, while zearalenone appeared to be a true endocrine-disrupting compound.

Rapid analysis of glutamate, glutamine and GABA in mice frontal cortex microdialysis samples using HPLC coupled to electrospray tandem mass spectrometry.

In vivo measurement of multiple neurotransmitters is highly interesting but remains challenging in the field of neuroscience. GABA and l-glutamic acid are the major inhibitory and excitatory neurotransmitters, respectively, in the central nervous system, and their changes are related to a variety of diseases such as anxiety and major depressive disorder. This study described a simple method allowing the simultaneous LC-MS/MS quantification of l-glutamic acid, glutamine and GABA. Analytes were acquired from samples of the prefrontal cortex by microdialysis technique in freely moving mice. The chromatographic separation was performed by hydrophilic interaction liquid chromatography (HILIC) with a core-shell ammonium-sulfonic acid modified silica column using a gradient elution with mobile phases consisting of a 25 mM pH 3.5 ammonium formate buffer and acetonitrile. The detection of l-glutamic acid, glutamine and GABA, as well as the internal standards [d6]-GABA and [d5]-glutamate was performed on a triple quadrupole mass spectrometer in positive electrospray ionization and multiple reaction monitoring mode. The limit of quantification was 0.63 ng/ml for GABA, 1.25 ng/ml for l-glutamic acid and 3.15 ng/ml for glutamine, and the intra-day and inter-day accuracy and precision have been assessed for the three analytes. Therefore, the physiological relevance of the method was successfully applied for the determination of basal extracellular levels and potassium-evoked release of these neuroactive substances in the prefrontal cortex in adult awake C57BL/6 mice.