Complex mixtures of organic chemicals extracted from representative but not directly related environmental samples (wastewater, surface water, fish), food items (drinking water, fish, milk) and human blood were tested in 22 in vitro bioassays targeting pathways associated with neurodevelopmental and reproductive health. Extraction methods were optimized to extract common chemicals across matrices capturing both persistent and nonpersistent, neutral and charged organic chemicals─albeit with some bias toward more hydrophilic chemicals over highly hydrophobic chemicals. Most bioassay end points─except genotoxicity─were responsive, with strongest effects observed higher up the food chain in fish and humans. Experimental mixture effects of 24 chemicals quantified in these extracts conformed to the mixture prediction model of concentration addition in the six most responsive bioassays, namely neurite outgrowth inhibition, mitochondrial membrane potential inhibition, transthyretin protein binding, sodium-iodide symporter inhibition and androgen receptor antagonism. Designed mixtures explained little of total bioactivity, indicating that many of the thousands of unannotated molecular features detected by nontarget analysis contribute to mixture effects. Preliminary effect-based trigger (EBT) values defined for water and food by extrapolation from safe levels of individual chemicals indicate no immediate health risks at these average contamination levels. The high complexity and multivalent bioactivity of these mixtures on neurodevelopmental and reproductive pathways necessitate further toxicological scrutiny.

Pyrethroid insecticides are used worldwide, yet their potential effects on early human development remain poorly understood. We applied the PluriLum assay, a human induced pluripotent stem cell-based 3D in vitro model, to evaluate the embryotoxicity of three commonly used pyrethroids (α-cypermethrin, deltamethrin, and etofenprox), and their shared metabolite 3-phenoxybenzoic acid (3-PBA). Embryoid bodies (EBs) were repeatedly exposed to these compounds throughout their differentiation into cardiomyocytes, and effects on cardiomyocyte beating, expression of the early cardiac marker NKX2.5, as well as their impact at a transcriptional level was assessed. The three pyrethroids were tested in combination at two different mixture compositions to investigate their potential for additivity. All three pyrethroids impaired cardiomyocyte differentiation at micromolar levels, with the following potency ranking: α-cypermethrin > etofenprox > deltamethrin. At higher concentrations, α-cypermethrin also reduced cardiomyocyte contractility. In contrast, 3-PBA showed no significant effects on neither differentiation nor contractile function. The pyrethroid mixtures followed the principle of concentration addition. An exploratory transcriptomic analysis revealed that α-cypermethrin and deltamethrin significantly altered the EBs gene expression profiles, affecting pathways related to ion channel activity, receptor signalling, and extracellular matrix organization. These findings suggest that exposure to pyrethroids may interfere with early human cardiac development through effects on multiple molecular targets. This study also highlights the value of the PluriLum assay as a human-relevant platform for assessing the embryotoxic potential of environmental chemicals.

Humans are continuously exposed to a wide array of exogenous chemicals via dietary intake, environmental sources, and the use of personal care products. This includes per- and polyfluoroalkyl substances (PFAS), a class of highly persistent compounds that have been associated with developmental effects in humans. This study assessed the effects of four legacy PFAS, namely PFOS, PFOA, PFNA and PFHxS, and mixtures thereof in the PluriLum assay, a 3D human induced pluripotent stem cell (hiPSC)-based model for embryotoxicity testing. We established the individual embryotoxic potencies of PFAS, with PFNA exhibiting the highest potency, followed by PFOS, PFOA and PFHxS. The four PFAS were evaluated in three reconstituted mixtures, prepared either to reflect identical potencies ("equipotent mixture") or the average serum concentrations reported for the European adult or child population ("real-life mixtures"). Comparing observed versus predicted mixture responses demonstrated concentration additivity throughout the entire range of tested concentrations. Studies on uptake in 3D embryoid bodies revealed the highest bioaccumulation of PFOS, followed by PFNA, PFOA, and PFHxS. Moreover, less than 2% of the nominally added PFAS could be recovered in the embryoid bodies. RNA sequencing showed that relatively few genes were affected by PFOS, PFNA and PFOA, however expression of genes related to focal adhesion and functional pathways associated with cardiac, cardiomyocyte and muscle tissue development was significantly changed. Notably, PFOS affected the greatest number of embryonic development pathways. In conclusion, the four tested PFAS significantly impaired cardiomyocyte differentiation, indicating embryotoxicity. The combined responses were consistent with the concentration addition principle, supported by shared functional pathways and indicative of common sites of molecular action.

Background/Objectives: Endocrine therapies that comprise anti-estrogens and aromatase inhibitors (AIs) are the standard treatment for estrogen receptor-positive (ER+) (Luminal A) breast cancer—the most prevalent subtype. However, the emergence of resistance restricts their success by causing tumor relapse and re-growth, which demands a switch towards other therapeutic approaches in order to minimize or overcome resistance. Indeed, this clinical limitation highlights the search for new molecules to improve cancer treatment. Recently, strategies that address multiple targets have been emerging, and multi-target drugs have the potential to become the future anti-cancer molecules. Our group has been searching for new multi-target compounds, and as part of this, our study aims to understand the anti-cancer and multi-target potential of three new steroidal aromatase inhibitors (AIs): 7α-methylandrost-4-en-17-one (6), 7α-methylandrost-4-ene-3,17-dione (10a) and androsta-4,9(11)-diene-3,17-dione (13). Methods: Their in vitro actions and molecular mechanisms were elucidated in a sensitive ER+ aromatase-overexpressing breast cancer cell line, MCF-7aro cells, as well as in an AI-resistant ER+ breast cancer cell line, LTEDaro cells. Results: All the new AIs (10 µM) prevented the proliferation of MCF-7aro cells by arresting cell cycle progression. Interestingly, all AIs (10 µM) act as androgen receptor (AR) agonists and modulate ER levels, synthesis and signaling to induce the apoptosis of ER+ breast cancer cells. Additionally, these new AIs (10 µM) also re-sensitize resistant cells by promoting apoptosis, offering a therapeutic benefit. Conclusions: Overall, new steroidal polypharmacological compounds have been discovered that, by acting as AIs, ER modulators and AR agonists, impair ER+ breast cancer cell growth. Overall, this study is a breakthrough on drug discovery as it presents new molecules with appealing anti-cancer properties and multi-target action for the treatment of ER+ breast cancer.

Chemical contaminants are widely dispersed in the environment in all its dimensions, posing significant public health problems. Comprehensive knowledge of these stressors is a prerequisite for assessing the associated risk and implementing public policy measures to reduce the level of population exposure. Nontargeted suspect screening approaches broaden the knowledge of the chemical human exposome. We developed and used a suspect screening method based on large spectral libraries. Chemical profiling was based on a combined LC- and GC-HRMS approach. The methodology was applied to 16 samples spanning the environment, food, and health continuum. Using a combination of matching and scoring data, a total of 547 compounds were likely identified, from which the chemical structure of 63 molecules was confirmed to the highest level of certainty. Wastewater, and more generally environmental samples, had the highest number of chemicals detected, while fish samples had a lower number. Pharmaceuticals, pesticides, and personal care product-related compounds were found to be the most common compounds in and between the extracts, particularly in water and serum samples. Many natural and endogenous compounds were consistently annotated in the samples submitted for analysis, regardless of the compartment investigated.

Cannabinoids have been used as anti-emetic agents in cancer. However, multiple studies suggest that cannabinoids present important anti-tumor actions as well. Estrogen receptor-positive (ER+) breast cancer is the most diagnosed breast cancer subtype, and despite the success of endocrine therapy, endocrine resistance development is a major challenge, demanding the discovery or implementation of alternative therapeutic approaches. In line with this, and following our previous work, the benefits of combining the aromatase inhibitors (AIs) used in the clinic, anastrozole (Ana), letrozole (Let), and exemestane (Exe), with cannabinol (CBN) were evaluated. Experiments were performed in MCF-7aro cells and spheroids to assess activity against specific molecular targets and underlying mechanisms of action. Among the three AIs studied, only the combination of CBN with Exe induced a significant beneficial impact on viability and growth of ER+ breast cancer cells and spheroids. Our results demonstrated that this combination was more effective than Exe in preventing the expression of aromatase and in modulating ERα and androgen receptor (AR) activity. In fact, the results revealed that CBN can prevent de novo synthesis of aromatase, surpass Exe's weak estrogen-like effect, and avoid the unfavorable overexpression of AR. By comparing these two therapeutic strategies, as well as the previously studied combination of Exe plus cannabidiol (CBD), differential transcriptome profiles were detected, which may help to better understand the mechanism of action of cannabinoids and disclose their full potential in breast cancer treatment. In conclusion, this study strengthens the hypothesis that cannabinoids are important anti-cancer agents with attractive co-adjuvant properties.

Although the herbicide linuron is banned for use in the EU due to its reproductive and developmental toxicity, it can still be found in randomly sampled foods grown in and outside the EU. It is not clear if metabolites of linuron can contribute to the endocrine disrupting effects following exposure to the parent compound. To address this gap, we analysed linuron and the metabolites 1-(3,4-dichlorophenyl) urea (DCU), 3,4-dichloroaniline (DCA) and 1-(3,4-dichlorophenyl)-3-methoxyurea (DCXU) for androgen receptor (AR) activities and effects on steroidogenesis. Generally, linuron and the metabolites showed qualitatively similar antiandrogenic profiles, but potencies varied. All compounds were AR antagonists, with linuron showing highest potency (IC50 of 2.8 μM). The overall picture of effects on steroidogenesis showed that linuron and metabolites increased the levels of estrogens and corticosteroids, whereas the synthesis of androgens was inhibited. The metabolite DCU was by far the most potent inhibitor of testosterone synthesis (IC50 of 6.7 μM compared to IC50 of 51.1 μM for linuron). We suggest that it is likely that the metabolites contribute to the antiandrogenic effects of linuron in vivo, especially by inhibiting testosterone synthesis.

Background: Breast cancer therapy has been facing remarkable changes. Classic treatments are now combined with other therapies to improve efficacy and surpass resistance. Indeed, the emergence of resistance demands the development of novel therapeutic approaches. Due to key estrogen signaling, estrogen receptor-positive (ER+) breast cancer treatment has always been focused on aromatase inhibition and ER modulation. Lately, the effects of phytocannabinoids, mainly Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), have been evaluated in different cancers, including breast. However, Cannabis sativa contains more than 120 phytocannabinoids less researched and understood. Methods: Here, we evaluated, both in silico and in vitro, the ability of 129 phytocannabinoids to modulate important molecular targets in ER+ breast cancer: aromatase, ER, and androgen receptor (AR). Results: In silico results suggested that some cannabinoids may inhibit aromatase and act as ERα antagonists. Nine selected cannabinoids showed, in vitro, potential to act either as ER antagonists with inverse agonist properties, or as ER agonists. Moreover, these cannabinoids were considered as weak aromatase inhibitors and AR antagonists with inverse agonist action. Conclusions: Overall, we present, for the first time, a comprehensive analysis of the actions of the phytocannabinoids in targets of ER+ breast tumors, pointing out their therapeutic potential in cancer and in other diseases.

To meet the growing demand for developmental toxicity assessment of chemicals, New Approach Methodologies (NAMs) are needed. Previously, we developed two 3D in vitro assays based on human-induced pluripotent stem cells (hiPSC) and cardiomyocyte differentiation: the PluriBeat assay, based on assessment of beating differentiated embryoid bodies, and the PluriLum assay, a reporter gene assay based on the expression of the early cardiac marker NKX2.5 ; both promising assays for predicting embryotoxic effects of chemicals and drugs. In this work, we aimed to further describe the predictive power of the PluriLum assay and compare its sensitivity with PluriBeat and similar human stem cell-based assays developed by others. For this purpose, we assessed the toxicity of a panel of ten chemicals from different chemical classes, consisting of the known developmental toxicants 5-fluorouracil, all- trans retinoic acid and valproic acid, as well as the negative control compounds ascorbic acid and folic acid. In addition, the fungicides epoxiconazole and prochloraz, and three perfluoroalkyl substances (PFAS), PFOS, PFOA and GenX were tested. Generally, the PluriLum assay displayed higher sensitivity when compared to the PluriBeat assay. For several compounds the luminescence readout of the PluriLum assay showed effects not detected by the PluriBeat assay, including two PFAS compounds and the two fungicides. Overall, we find that the PluriLum assay has the potential to provide a fast and objective detection of developmental toxicants and has a level of sensitivity that is comparable to or higher than other in vitro assays also based on human stem cells and cardiomyocyte differentiation for assessment of developmental toxicity.

New approach methodologies (NAMs) for predicting embryotoxicity and developmental toxicity are urgently needed for generating human relevant data, while reducing turnover time and costs, and alleviating ethical concerns related to the use of animal models. We have previously developed the PluriLum assay, a NKX2.5-reporter gene 3D model using human-induced pluripotent stem cells (hiPSCs) that are genetically modified to enable the assessment of adverse effects of chemicals on the early-stage embryo. Aiming at improving the predictive value of the PluriLum assay for future screening purposes, we sought to introduce standardization steps to the protocol, improving the overall robustness of the PluriLum assay, as well as a shortening of the assay protocol. First, we showed that the initial size of embryoid bodies (EBs) is crucial for a proper differentiation into cardiomyocytes and overall reproducibility of the assay. When the starting diameter of the EBs exceeds 500 µm, robust differentiation can be anticipated. In terms of reproducibility, exposure to the fungicide epoxiconazole at smaller initial diameters resulted in a larger variation of the derived data, compared to more reliable concentration–response curves obtained using spheroids with larger initial diameters. We further investigated the ideal length of the differentiation protocol, resulting in a shortening of the PluriLum assay by 24 h to 7 days. Following exposure to the teratogens all-trans and 13-cis retinoic acid, both cardiomyocyte contraction and measurement of NKX2.5-derived luminescence were recorded with a similar or increased sensitivity after 6 days of differentiation when compared to the original 7 days. Finally, we have introduced an efficient step for enzymatic dissociation of the EBs at assay termination. This allows for an even splitting of the individual EBs and testing of additional endpoints other than the NKX2.5-luciferase reporter, which was demonstrated in this work by the simultaneous assessment of ATP levels. In conclusion, we have introduced standardizations and streamlined the PluriLum assay protocol to improve its suitability as a NAM for screening of a large number of chemicals for developmental toxicity testing.

The predominantly animal-centric approach of chemical safety assessment has increasingly come under pressure. Society is questioning overall performance, sustainability, continued relevance for human health risk assessment and ethics of this system, demanding a change of paradigm. At the same time, the scientific toolbox used for risk assessment is continuously enriched by the development of “New Approach Methodologies” (NAMs). While this term does not define the age or the state of readiness of the innovation, it covers a wide range of methods, including quantitative structure-activity relationship (QSAR) predictions, high-throughput screening (HTS) bioassays, omics applications, cell cultures, organoids, microphysiological systems (MPS), machine learning models and artificial intelligence (AI). In addition to promising faster and more efficient toxicity testing, NAMs have the potential to fundamentally transform today’s regulatory work by allowing more human-relevant decision-making in terms of both hazard and exposure assessment. Yet, several obstacles hamper a broader application of NAMs in current regulatory risk assessment. Constraints in addressing repeated-dose toxicity, with particular reference to the chronic toxicity, and hesitance from relevant stakeholders, are major challenges for the implementation of NAMs in a broader context. Moreover, issues regarding predictivity, reproducibility and quantification need to be addressed and regulatory and legislative frameworks need to be adapted to NAMs. The conceptual perspective presented here has its focus on hazard assessment and is grounded on the main findings and conclusions from a symposium and workshop held in Berlin in November 2021. It intends to provide further insights into how NAMs can be gradually integrated into chemical risk assessment aimed at protection of human health, until eventually the current paradigm is replaced by an animal-free “Next Generation Risk Assessment” (NGRA).