Development of an in vitro neuroblastoma 3D model and its application for sterigmatocystin-induced cytotoxicity testing

Estrogen G-Protein Coupled Receptor Antagonist G15 Promotes Tau Clearance in 2D and 3D Tauopathy Models

Several studies have investigated the efficacy of estrogen in age-related diseases, showing promising results in several models of neurodegeneration, such as Alzheimer's disease. Animal and cellular models indicate that estrogen and related compounds can reduce the accumulation of amyloid plaques and tau protein, which are associated with Alzheimer's disease. Therefore, it is crucial to develop appropriate models to study the neuroprotective effects of estrogen, and three-dimensional (3D) models have recently emerged as a viable alternative to animal testing. This study aimed to investigate the potential of 3D tauopathy models for drug testing, focusing on estrogen-related signaling. The results demonstrate that a scaffold-free neurospheroid with inducible tau protein expression allows for the observation of tau protein distribution throughout the spheroid. Moreover, the study found that the G-protein-coupled estrogen receptor antagonist, G15, reduced tau protein concentration in both 2D and 3D models. Thus, this study highlights the importance of estrogen-related compounds in 3D cultures, which could facilitate investigations into the mechanisms of action and the neuroprotective role of estrogen in neurodegenerative diseases.

Development of an Easy-To-Use Microfluidic System to Assess Dynamic Exposure to Mycotoxins in 3D Culture Models: Evaluation of Ochratoxin A and Patulin Cytotoxicity

Mycotoxins are among the most concerning natural toxic food contaminants. Over the years, significant efforts have been made to characterize the risk associated with their exposure. However, assessing their toxicity has so far been elusive due to the lack of adequate models that closely mimic the physiological conditions of human cells in vivo. Here, we present the SpheroFlow Device (SFD), an efficient microfluidic platform designed, manufactured, and validated to evaluate mycotoxin-induced cytotoxicity under dynamic and continuous exposure in 3D culture settings. In the present study, we integrated human neuroblastoma SH-SY5Y spheroids into the SFD to assess the acute toxicity induced by the mycotoxins ochratoxin A (OTA) and patulin (PAT). The developed system enabled qualitative and quantitative measurements of concentration-response relationships and provided accurate control over the culture microenvironment. Our findings show that by enhancing 3D culture model by applying dynamic flow, SH-SY5Y spheroids exhibited different sensitivities to OTA and PAT compared to conventional static SH-SY5Y spheroids, confirming the critical role of culture models in mycotoxin toxicity assessment. This is the first study assessing the neurotoxicity of OTA and PAT on 3D neuroblastoma spheroids considering the contribution of fluid flow.

Amitraz mechanisms of cytotoxicity in a characterized SH-SY5Y cells spheroid model

In recent years, spheroids (tridimensional cell cultures) have emerged as a more physiologically relevant replacement for monolayer models. Their distinctive advantage is the formation of an extracellular matrix that facilitates enhanced cellular interaction and communication, approximating the conditions observed in vivo. Therefore, the potential for conducting intricate cellular and molecular techniques in these models could offer a more precise assessment of pivotal proteins within various cellular pathways of interest. Amitraz (AMZ), an acaricide classified as a formamidine chemical, has been detected in honey at concentrations exceeding legal limits. The objective of this study was to characterize a spheroid model of SH-SY5Y cells and determine the cytotoxic effect of AMZ and its mechanisms of action on this spheroid. The formation of mature spheroids was observed on the seventh day following seeding. The results obtained with SH-SY5Y spheroids were an IC50 of 238.8 ± 17 µM and 224.3 ± 19 µM, respectively, after 24 and 48 h of exposure by the MTT assay. The findings revealed that AMZ did not exhibit any indications of inflammatory over-expression markers in the spheroids. Nevertheless, at 238.8 µM of AMZ, an increase incidence of late apoptosis within spheroid cells and Bcl-2 protein expression in peripheral spheroid cells were observed through annexin V and propidium iodide probe and immunofluorescence analysis. In conclusion, the results demonstrated that spheroids could be useful for an accurate assessment of toxicity, representing a viable alternative method for determining the mechanisms of action of AMZ and related compounds.

Integrated Approach to Cyclopiazonic Acid Cytotoxicity Using In Vitro (2D and 3D Models) and In Silico Methods

Cyclopiazonic acid (CPA) is an indole-tetramic acid neurotoxin produced by Aspergillus and Penicillium genera present mainly in fruit, cereals and nuts. This study compares the cytotoxicity produced by CPA after 24, 48 and 72 h of exposure using both monolayers and 3D spheroids in human neuroblastoma SH-SY5Y cells. Furthermore, CPA toxicokinetics was evaluated using in silico models. Cytotoxicity increased dose- and time-dependently, as shown by the MTT assay. The lowest CPA IC50 values were found in the monolayer study compared to the 3D spheroids at all exposure times (24 h: 864.01 vs. 1132; 48 h: 437 vs. 1069; 72 h: 392 vs. 567 nM). The CPA exposure on SH-SY5Y spheroid organization and morphology was also studied. Morphological changes, including spheroid disaggregation, were observed after mycotoxin exposure. The in silico methods, SwissADME and admetSAR, were used for short and full ADMEt profiles of CPA. The ADMEt predictive profile shows high gastrointestinal absorption and ability to penetrate the blood-brain barrier. Including in silico studies emphasizes the comprehensive approach to understanding mycotoxin toxicity and risk assessment. By combining in vitro 3D spheroid models with computational simulations, this study aims to provide a holistic perspective on the effects of CPA, enhancing the accuracy and relevance of our findings.

Sterigmatocystin declines mouse oocyte quality by inducing ferroptosis and asymmetric division defects

BACKGROUND

Sterigmatocystin (STE) is a mycotoxin widely found in contaminated food and foodstuffs, and excessive long-term exposure to STE is associated with several health issues, including infertility. However, there is little information available regarding the effects of STE toxin on the female reproductive system, particularly concerning oocyte maturation.

METHODS

In the present study, we investigated the toxic effects of STE on mouse oocyte maturation. We also used Western blot, immunofluorescence, and image quantification analyses to assess the impact of STE exposure on the oocyte maturation progression, mitochondrial distribution, oxidative stress, DNA damages, oocyte ferroptosis and asymmetric division defects.

RESULTS

Our results revealed that STE exposure disrupted mouse oocyte maturation progression. When we examined the cellular changes following 100 µM STE treatment, we found that STE adversely affected polar body extrusion and induced asymmetric division defects in oocytes. RNA-sequencing data showed that STE exposure affects the expression of several pathway-correlated genes during oocyte meiosis in mice, suggesting its toxicity to oocytes. Based on the RNA-seq data, we showed that STE exposure induced oxidative stress and caused DNA damage in oocytes. Besides, ferroptosis and α-tubulin acetylation were also found in STE-exposed oocytes. Moreover, we determined that STE exposure resulted in reduced RAF1 protein expression in mouse oocytes, and inhibition of RAF1 activity also causes defects in asymmetric division of mouse oocytes.

CONCLUSIONS

Collectively, our research provides novel insights into the molecular mechanisms whereby STE contributes to abnormal meiosis.

Combined targeted therapy with PI3K and CDK4/6, or FGFR inhibitors show synergistic effects in a neuroblastoma spheroid culture model

AIM

Neuroblastoma (NB) is, in spite of current intensive therapy with severe side effects, still not cured so new therapies are needed. Recently, we showed combining phosphoinositide 3-kinase (PI3K) (BYL719), fibroblast growth factor receptor (FGFR) (JNJ-42756493) and cyclin-dependent kinase 4/6 (CDK4/6) (PD-0332991) inhibitors, in vitro in NB cell lines grown as monolayers had synergistic effects. However, there were variations depending on the combinations used and the targeted NB cell lines. To obtain further information and to mimic more natural circumstances, we investigated the effects of single and combined administrations of the above inhibitors in spheroid NB-cultures.

MATERIAL AND METHODS

Spheroid cultures of NB cell lines SK-N-AS, SK-N-BE(2)-C, SK-N-FI and SK-N-SH were established and treated with single and combined administrations of BYL719, JNJ-42756493, and PD-0332991 and followed for growth, viability, proliferation, cytotoxicity and migration.

KEY FINDINGS

Single inhibitor administrations gave dose dependent responses with regard to growth and viability and their combinations were efficient and resulted in a range of additive and synergistic effects. The responses to individual drugs and their various combinations were predominantly alike regardless of whether the cells were cultivated in monolayer or D spheroid NB models. However, in general, slightly higher drug concentrations were necessary in spheroidcultures.

SIGNIFICANCE

This study provides pre-clinical evidence that single PI3K, FGFR, and CDK4/6, inhibitors exhibit promising anti-NB activity and when combined lower doses of the drugs could be also used in spheroid NB-cultures, supporting the pursuit of further in vitro and in vivo studies in preparation for future potential clinical use.

Differential Competitive Growth of Transgenic Subclones of Neuroblastoma Cells Expressing Different Levels of Cathepsin D Co-Cultured in 2D and 3D in Response to EGF: Implications in Tumor Heterogeneity and Metastasis

Neuroblastoma (NB) is an embryonal tumor arising from the sympathetic central nervous system. The epidermal growth factor (EGF) plays a role in NB growth and metastatic behavior. Recently, we have demonstrated that cathepsin D (CD) contrasts EGF-induced NB cell growth in 2D by downregulating EGFR/MAPK signaling. Aggressive NB is highly metastatic to the bone and the brain. In the metastatic process, adherent cells detach to form clusters of suspended cells that adhere once they reach the metastatic site and form secondary colonies. Whether CD is involved in the survival of metastatic NB clones is not known. Therefore, in this study, we addressed how CD differentially affects cell growth in suspension versus the adherent condition. To mimic tumor heterogeneity, we co-cultured transgenic clones silenced for or overexpressing CD. We compared the growth kinetics of such mixed clones in 2D and 3D models in response to EGF, and we found that the Over CD clone had an advantage for growth in suspension, while the CD knocked-down clone was favored for the adherent growth in 2D. Interestingly, on switching from 3D to 2D culture conditions, the expression of E-cadherin and of N-cadherin increased in the KD-CD and Over CD clones, respectively. The fact that CD plays a dual role in cancer cell growth in 2D and 3D conditions indicates that during clonal evolution, subclones expressing different level of CD may arise, which confers survival and growth advantages depending on the metastatic step. By searching the TCGA database, we found up to 38 miRNAs capable of downregulating CD. Interestingly, these miRNAs are associated with biological processes controlling cell adhesion and cell migration. The present findings support the view that during NB growth on a substrate or when spreading as floating neurospheres, CD expression is epigenetically modulated to confer survival advantage. Thus, epigenetic targeting of CD could represent an additional strategy to prevent NB metastases.

Comparative Study of Spheroids (3D) and Monolayer Cultures (2D) for the In Vitro Assessment of Cytotoxicity Induced by the Mycotoxins Sterigmatocystin, Ochratoxin A and Patulin

Mycotoxins are secondary metabolites produced by filamentous fungi associated with a variety of acute and chronic foodborne diseases. Current toxicology studies mainly rely on monolayer cell cultures and animal models, which are undeniably affected by several limitations. To bridge the gap between the current in vitro toxicology approach and the in vivo predictability of the data, we here investigated the cytotoxic effects induced by the mycotoxins sterigmatocystin (STE), ochratoxin A (OTA) and patulin (PAT) on different 2D and 3D cell cultures. We focused on human tumours (neuroblastoma SH-SY5Y cells and epithelial breast cancer MDA-MB-213 cells) and healthy cells (bone marrow-derived mesenchymal stem cells, BM-MSC, and umbilical vein endothelial cells, HUVECs). The cytotoxicity of STE, OTA, and PAT was determined after 24, 48 and 72 h of exposure using an ATP assay in both culture models. Three-dimensional spheroids' morphology was also analysed using the MATLAB-based open source software AnaSP 1.4 version. Our results highlight how each cell line and different culture models showed specific sensitivities, reinforcing the importance of using more complex models for toxicology studies and a multiple cell line approach for an improved and more comprehensive risk assessment.

Harmaline to Human Mitochondrial Caseinolytic Serine Protease Activation for Pediatric Diffuse Intrinsic Pontine Glioma Treatment

Diffuse intrinsic pontine glioma (DIPG), affecting children aged 4-7 years, is a rare, aggressive tumor that originates in the pons and then spreads to nearby tissue. DIPG is the leading cause of death for pediatric brain tumors due to its infiltrative nature and inoperability. Radiotherapy has only a palliative effect on stabilizing symptoms. In silico and preclinical studies identified ONC201 as a cytotoxic agent against some human cancer cell lines, including DIPG ones. A single-crystal X-ray analysis of the complex of the human mitochondrial caseinolytic serine protease type C (hClpP) and ONC201 (PDB ID: 6DL7) allowed hClpP to be identified as its main target. The hyperactivation of hClpP causes damage to mitochondrial oxidative phosphorylation and cell death. In some DIPG patients receiving ONC201, an acquired resistance was observed. In this context, a wide program was initiated to discover original scaffolds for new hClpP activators to treat ONC201-non-responding patients. Harmaline, a small molecule belonging to the chemical class of β-carboline, was identified through Fingerprints for Ligands and Proteins (FLAP), a structure-based virtual screening approach. Molecular dynamics simulations and a deep in vitro investigation showed interesting information on the interaction and activation of hClpP by harmaline.

The Growing Importance of Three-Dimensional Models and Microphysiological Systems in the Assessment of Mycotoxin Toxicity

Current investigations in the field of toxicology mostly rely on 2D cell cultures and animal models. Although well-accepted, the traditional 2D cell-culture approach has evident drawbacks and is distant from the in vivo microenvironment. To overcome these limitations, increasing efforts have been made in the development of alternative models that can better recapitulate the in vivo architecture of tissues and organs. Even though the use of 3D cultures is gaining popularity, there are still open questions on their robustness and standardization. In this review, we discuss the current spheroid culture and organ-on-a-chip techniques as well as the main conceptual and technical considerations for the correct establishment of such models. For each system, the toxicological functional assays are then discussed, highlighting their major advantages, disadvantages, and limitations. Finally, a focus on the applications of 3D cell culture for mycotoxin toxicity assessments is provided. Given the known difficulties in defining the safety ranges of exposure for regulatory agency policies, we are confident that the application of alternative methods may greatly improve the overall risk assessment.

Advanced 3D Models of Human Brain Tissue Using Neural Cell Lines: State-of-the-Art and Future Prospects

Human-relevant three-dimensional (3D) models of cerebral tissue can be invaluable tools to boost our understanding of the cellular mechanisms underlying brain pathophysiology. Nowadays, the accessibility, isolation and harvesting of human neural cells represents a bottleneck for obtaining reproducible and accurate models and gaining insights in the fields of oncology, neurodegenerative diseases and toxicology. In this scenario, given their low cost, ease of culture and reproducibility, neural cell lines constitute a key tool for developing usable and reliable models of the human brain. Here, we review the most recent advances in 3D constructs laden with neural cell lines, highlighting their advantages and limitations and their possible future applications.

Tumour growth: An approach to calibrate parameters of a multiphase porous media model based on in vitro observations of Neuroblastoma spheroid growth in a hydrogel microenvironment

To unravel processes that lead to the growth of solid tumours, it is necessary to link knowledge of cancer biology with the physical properties of the tumour and its interaction with the surrounding microenvironment. Our understanding of the underlying mechanisms is however still imprecise. We therefore developed computational physics-based models, which incorporate the interaction of the tumour with its surroundings based on the theory of porous media. However, the experimental validation of such models represents a challenge to its clinical use as a prognostic tool. This study combines a physics-based model with in vitro experiments based on microfluidic devices used to mimic a three-dimensional tumour microenvironment. By conducting a global sensitivity analysis, we identify the most influential input parameters and infer their posterior distribution based on Bayesian calibration. The resulting probability density is in agreement with the scattering of the experimental data and thus validates the proposed workflow. This study demonstrates the huge challenges associated with determining precise parameters with usually only limited data for such complex processes and models, but also demonstrates in general how to indirectly characterise the mechanical properties of neuroblastoma spheroids that cannot feasibly be measured experimentally.

Comparison Evaluation of the Biological Effects of Sterigmatocystin and Aflatoxin B1 Utilizing SOS-Chromotest and a Novel Zebrafish (Danio rerio) Embryo Microinjection Method

Aflatoxin B1 (AFB1) is a potent mycotoxin and natural carcinogen. The primary producers of AFB1 are Aspergillus flavus and A. parasiticus. Sterigmatocystin (STC), another mycotoxin, shares its biosynthetic pathway with aflatoxins. While there are abundant data on the biological effects of AFB1, STC is not well characterised. According to published data, AFB1 is more harmful to biological systems than STC. It has been suggested that STC is about one-tenth as potent a mutagen as AFB1 as measured by the Ames test. In this research, the biological effects of S9 rat liver homogenate-activated and non-activated STC and AFB1 were compared using two different biomonitoring systems, SOS-Chromotest and a recently developed microinjection zebrafish embryo method. When comparing the treatments, activated STC caused the highest mortality and number of DNA strand breaks across all injected volumes. Based on the E. coli SOS-Chromotest, the two toxins exerted the same genotoxicities. Moreover, according to the newly developed zebrafish microinjection method, STC appeared more toxic than AFB1. The scarce information correlating AFB1 and STC toxicity suggests that AFB1 is a more potent genotoxin than STC. Our findings contradict this assumption and illustrate the need for more complex biomonitoring systems for mycotoxin risk assessment.