Mycotoxin citrinin induced cell cycle G2/M arrest and numerical chromosomal aberration associated with disruption of microtubule formation in human cells

Involvement of pro-inflammatory mediators and cell cycle disruption in neuronal cells induced by gliotoxin and ochratoxin A after individual and combined exposure

Mycotoxins such as gliotoxin (GTX) and ochratoxin A (OTA) are secondary metabolites of Aspergillus and Penicillum found in food and feed. Both mycotoxins have shown to exert a detrimental effect on neuronal activity. The following study was carried out to elucidate the mechanisms by which GTX and OTA exert their toxicity. Non-differentiated SH-SY5Y neuronal-like cells were treated with GTX, OTA and their combinations to assess their cytotoxic effect using the MTT assay during 24, 48 and 72 h of exposure. Based on the results of the cytotoxic assays, cell cycle proliferation and immunological mediators were measured by determining the production of IL-6 and TNF-α using flow cytometry and ELISA, respectively. The IC50 values obtained were 1.24 and 1.35 µM when SH-SY5Y cells were treated with GTX at 48 h and 72 h, respectively. IC50 values of 8.25, 5.49 and 4.5 µM were obtained for OTA treatment at 24 h, 48 h and 72 h, respectively. The SubG0 phase increased in both treatments at 24 and 48 h. On the other hand, IL-6 and TNF-α production was increased in all mycotoxin treatments studied and was more pronounced for [GTX + OTA] after 48 h exposure. The additive and synergistic effect observed by the isobologram analysis between GTX and OTA resulted to a higher cytotoxicity which can be explained by the increased production of IL-6 and TNF-α inflammatory mediators that play an important role in the toxicity mechanism of these mycotoxins.

On the Mechanisms of the Cardiotoxic Effect of Lead Oxide Nanoparticles

Lead compounds are one of the most common pollutants of the workplace air and the environment. In the occupational setting, the sources of their emission, including in nanoscale form, are various technological processes associated with lead smelting and handling of non-ferrous metals and their alloys, the production of copper and batteries. Both lead poisoning and lead exposure without obvious signs of poisoning have a detrimental effect on the cardiovascular system. The purpose of this research was to investigate the mechanisms of the cardiotoxic effect of lead oxide nanoparticles (PbO NPs). The toxicological experiment involved male albino rats subchronically exposed to PbO NPs (49.6 ± 16.0 nm in size) instilled intraperitoneally in a suspension. We then assessed post-exposure hematological and biochemical parameters of blood and urine, histological and ultrastructural changes in cardiomyocytes, and non-invasively recorded electrocardiograms and blood pressure parameters in the rodents. Myocardial contractility was studied on isolated preparations of cardiac muscles. We established that PbO NPs induced oxidative stress and damage to the ultrastructure of cardiomyocytes, and decreased efficiency of the contractile function of the myocardium and blood pressure parameters. We also revealed such specific changes in the organism of the exposed rats as anemia, hypoxia, and hypocalcemia.

Exposure to Mycotoxin Citrinin Promotes Carcinogenic Potential of Human Renal Cells

Mycotoxin citrinin (CTN), commonly found in food and health supplements, may induce chromosomal instability. In this study, human renal proximal tubule epithelial cells (hRPTECs) that were exposed to CTN (10 and 20 μM) over 3 days exhibited numerical chromosomal aberrations. Short-term (3 days) and long-term (30 days) exposures to CTN significantly promoted mitotic spindle abnormalities, wound healing, cell migration, and anchorage-independent growth in human embryonic kidney 293 (HEK293) cells. Short-term exposure to 10 and 20 μM CTN increased the number of migrated cells on day 10 by 1.7 and 1.9 times, respectively. The number of anchorage-independent colonies increased from 2.2 ± 1.3 to 7.8 ± 0.6 after short-term exposure to 20 μM CTN and from 2.0 ± 1.0 to 12.0 ± 1.2 after long-term exposure. The transcriptomic profiles of CTN-treated HEK293 were subjected to over-representative analysis (ORA), gene set enrichment analysis (GSEA), and Ingenuity pathway analysis (IPA). Short-term exposure to CTN promoted the RTK/KRAS/RAF/MAPK cascade, while long-term exposure altered the extracellular matrix organization. Both short- and long-term CTN exposure activated cancer and cell cycle-related signaling pathways. These results demonstrate the carcinogenic potential of CTN in human cells and provide valuable insights into the cancer risk associated with CTN.

Mechanisms underlying citrinin-induced toxicity via oxidative stress and apoptosis-mediated by mitochondrial-dependent pathway in SH-SY5Y cells

Citrinin (CIT) is a mycotoxin produced as a secondary product by the genera Aspergillus, Penicillium, Monascus, and other strains. CIT has the potential for contaminating animal feed and human food such as maize, wheat, rye, barley, oats, rice, cheese, and sake. Although CIT is primarily known as a nephrotoxic mycotoxin, it also affects other organs, including the liver and bone marrow, and its mechanisms of toxicity have not been clearly elucidated. There is a further lack of studies investigating the potential for CIT-induced neurotoxicity and its mechanisms. In the current study, SH-SY5Y human neuroblastoma cell line was treated with CIT for 24 h to evaluate various toxicological endpoints, such as reactive oxygen species (ROS) production and apoptosis induction. Results indicate that CIT has an IC50 value of 250.90 μM and cell proliferation decreased significantly at 50 and 100 μM CIT concentrations. These same concentrations also caused elevated ROS production (≥34.76%), apoptosis (≥9.43-fold) and calcium ion mobilization (≥36.52%) in the cells. Results show a significant decrease in the mitochondrial membrane potential (≥86.8%). We also found that CIT significantly upregulated the expression of some genes related to oxidative stress and apoptosis, while downregulating others. These results suggest that apoptosis and oxidative stress may be involved in the mechanisms underlying CIT-induced neurotoxicity.

Citrinin as a potential anti-cancer therapy: A comprehensive review

Citrinin (CIT) is a polyketide-derived mycotoxin, which is produced by many fungal strains belonging to the gerena Monascus, Aspergillus, and Penicillium. It has been postulated that mycotoxins have several toxic mechanisms and are potentially used as antineoplastic agents. Therefore, the present study carried out a systematic review, including articles from 1978 to 2022, by collecting evidence in experimental studies of CIT antiplorifactive activity in cancer. The Data indicate that CIT intervenes in important mediators and cell signaling pathways, including MAPKs, ERK1/2, JNK, Bcl-2, BAX, caspases 3,6,7 and 9, p53, p21, PARP cleavage, MDA, reactive oxygen species (ROS) and antioxidant defenses (SOD, CAT, GST and GPX). These factors demonstrate the potential antitumor drug CIT in inducing cell death, reducing DNA repair capacity and inducing cytotoxic and genotoxic effects in cancer cells.

Triplex metallohelices have enantiomer-dependent mechanisms of action in colon cancer cells

Self-assembled enantiomers of an asymmetric di-iron metallohelix differ in their antiproliferative activities against HCT116 colon cancer cells such that the compound with Λ-helicity at the metals becomes more potent than the Δ compound with increasing exposure time. From concentration- and temperature-dependent ⁵⁷Fe isotopic labelling studies of cellular accumulation we postulate that while the more potent Λ enantiomer undergoes carrier-mediated efflux, for Δ the process is principally equilibrative. Cell fractionation studies demonstrate that both enantiomers localise in a similar fashion; compound is observed mostly within the cytoskeleton and/or genomic DNA, with significant amounts also found in the nucleus and membrane, but with negligible concentration in the cytosol. Cell cycle analyses using flow cytometry reveal that the Δ enantiomer induces mild arrest in the G₁ phase, while Λ causes a very large dose-dependent increase in the G₂/M population at a concentration significantly below the relevant IC₅₀. Correspondingly, G₂-M checkpoint failure as a result of Λ-metallohelix binding to DNA is shown to be feasible by linear dichroism studies, which indicate, in contrast to the Δ compound, a quite specific mode of binding, probably in the major groove. Further, spindle assembly checkpoint (SAC) failure, which could also be responsible for the observed G₂/M arrest, is established as a feasible mechanism for the Λ helix via drug combination (synergy) studies and the discovery of tubulin and actin inhibition. Here, while the Λ compound stabilizes F-actin and induces a distinct change in tubulin architecture of HCT116 cells, Δ promotes depolymerization and more subtle changes in microtubule and actin networks.

Interaction between environmental pollutants and cancer drug efficacy: Bisphenol A, Bisphenol A diglycidyl ether and Perfluorooctanoic acid reduce vincristine cytotoxicity in acute lymphoblastic leukemia cells

Every day, we are exposed to many environmental pollutants that can enter our body through different routes and cause adverse effects on our health. Epidemiological studies suggest that these pollutants are responsible for approximately nine million deaths per year. Acute lymphoblastic leukemia (ALL) represents one of the major cancers affecting children, and although substantial progress has been made in its treatment, relapses are frequent after initial treatment and are now one of the leading causes of cancer-related death in pediatric patients. Currently, relatively little attention is paid to pollutant exposure during drug treatment and this is not taken into account for dose setting or regulatory purposes. In this work, we investigated how bisphenol A (BPA), its derivative bisphenol A diglycidyl ether (BADGE), and perfluorooctanoic acid (PFOA) alter vincristine treatment in ALL when administered before or together with the drug. We found that these three pollutants at nanomolar concentrations, lower than those established by current regulations, can reduce the cytotoxic effects of vincristine on ALL cells. Interestingly, we found that this is only achieved when exposure to pollutants occurs prior to administration of the chemotherapeutic drug. Moreover, we found that this effect could be mediated by activation of the PI3K/AKT pathway and stabilization of microtubules. This work strengthens the idea of starting to take into account exposure to pollutants to improve the efficacy of chemotherapy treatments.

Consensus Virtual Screening Protocol Towards the Identification of Small Molecules Interacting with the Colchicine Binding Site of the Tubulin-microtubule System

Modification of the tubulin-microtubule (Tub-Mts) system has generated effective strategies for developing different treatments for cancer. A huge amount of clinical data about inhibitors of the tubulin-microtubule system have supported and validated the studies on this pharmacological target. However, many tubulin-microtubule inhibitors have been developed from representative and common scaffolds that cover a small region of the chemical space with limited structural innovation. The main goal of this study is to develop the first consensus virtual screening protocol for natural products (ligand- and structure-based drug design methods) tuned for the identification of new potential inhibitors of the Tub-Mts system. A combined strategy that involves molecular similarity, molecular docking, pharmacophore modeling, and in silico ADMET prediction has been employed to prioritize the selections of potential inhibitors of the Tub-Mts system. Five compounds were selected and further studied using molecular dynamics and binding energy predictions to characterize their possible binding mechanisms. Their structures correspond to 5-[2-(4-hydroxy-3-methoxyphenyl) ethyl]-2,3-dimethoxyphenol (1), 9,10-dihydro-3,4-dimethoxy-2,7-phenanthrenediol (2), 2-(3,4-dimethoxyphenyl)-5,7-dihydroxy-6-methoxy-4H-1-benzopyran-4-one (3), 13,14-epoxyparvifoline-4',5',6'-trimethoxybenzoate (4), and phenylmethyl 6-hydroxy-2,3-dimethoxybenzoate (5). Compounds 1-3 have been associated with literature reports that confirm their activity against several cancer cell lines, thus supporting the utility of this protocol.

Multi-Omics Reveal Additive Cytotoxicity Effects of Aflatoxin B1 and Aflatoxin M1 toward Intestinal NCM460 Cells

Aflatoxin B1 (AFB1) is a common crop contaminant, while aflatoxin M1 (AFM1) is implicated in milk safety. Humans are likely to be simultaneously exposed to AFB1 and AFM1; however, studies on the combined interactive effects of AFB1 and AFM1 are lacking. To fill this knowledge gap, transcriptomic, proteomic, and microRNA (miRNA)-sequencing approaches were used to investigate the toxic mechanisms underpinning combined AFB1 and AFM1 actions in vitro. Exposure to AFB1 (1.25–20 μM) and AFM1 (5–20 μM) for 48 h significantly decreased cell viability in the intestinal cell line, NCM460. Multi-omics analyses demonstrated that additive toxic effects were induced by combined AFB1 (2.5 μM) and AFM1 (2.5 μM) in NCM460 cells and were associated with p53 signaling pathway, a common pathway enriched by differentially expressed mRNAs/proteins/miRNAs. Specifically, based on p53 signaling, cross-omics showed that AFB1 and AFM1 reduced NCM460 cell viability via the hsa-miR-628-3p- and hsa-miR-217-5p-mediated regulation of cell surface death receptor (FAS), and also the hsa-miR-11-y-mediated regulation of cyclin dependent kinase 2 (CDK2). We provide new insights on biomarkers which reflect the cytotoxic effects of combined AFB1 and AFM1 toxicity.

Reorienting of pramipexole as a promising therapy for acute pancreatitis in a rat model by suppressing TLR-4\NF-κB p65\NLRP3 inflammasome signaling

OBJECTIVE

Acute pancreatitis (AP), a disorder of global importance, has a growing incidence and prevalence, particularly in the western world. Its complications include pseudo-cysts and chronic pancreatitis. Pramipexole (PMX), a D2/3 receptor selecting agonist used in Parkinsonism, has reported anti-inflammatory effects lately.

PURPOSE

Exploring the potential curative role of PMX in an l-arginine-induced acute pancreatitis rat model besides a possible mechanistic pathway.

METHODS

Rats were divided randomly into three groups: control, l-arginine, and "l-arginine + PMX". 7 days after AP induction, rats decapitated and estimated for serum amylase, lipase, glucose, pancreatic inflammatory mediators "toll-like receptor-4, nuclear factor- kappa B p65 ,serum tumor necrosis factor-α, NLRP3 inflammasome, caspase-1, interleukin-1 beta, oxidative biomarkers "malondialdehyde, myeloperoxidase, nitrite/nitrate, reduced glutathione, and the apoptotic marker "caspase-3", with pancreatic histopathological changes.

RESULTS

L-arginine mediated AP proved by elevated serum lipase and amylase, pancreatic inflammatory, oxidative and apoptotic markers with infiltration of inflammatory cells using hematoxylin and eosin stain. PMX improved all these adverse signs of AP greatly.

CONCLUSION

PMX might be considered as an innovative therapy for AP due to its remarkable antioxidant, anti-apoptotic, and anti-inflammatory effects, which are attributed to the suppression of the NLRP3 inflammasome and its downstream inflammatory cytokines.

1 An HPLC-MS/MS Method Using a Multitoxin Clean-up Column for Analysis of Seven Mycotoxins in Aquafeeds

BACKGROUND

In Guangdong Province of China, the climate here is very wet, so there are many different fungus living in the aquatic feeds, which produce mycotoxins. These compounds contaminate agriculture products world-wide and represent a great threat to human health. It is necessary to determine their contamination level in aquatic feeds.

OBJECTIVE

A high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method was developed for the quantitative analysis of aflatoxin B1, aflatoxin M1, T-2 toxin, HT-2 toxin, deoxynivalenol, ochratoxin, and zearalenone in the fish and shrimp feed.

METHODS

Samples were extracted with acetonitrile-water (V: V = 3:1), and degreased with acetonitrile-saturated hexane. Such obtained extract was cleaned up with a multitoxin column. The target compounds were separated on a C18 chromatographic column and analyzed simultaneously by electrospray ionization mass spectrometry in both positive or negative ion mode. Detected compounds were quantified by using the matrix-matched external standard method.

RESULTS

Under the optimized conditions, good linearities for the analytes in corresponding concentration range were obtained with correlation coefficients (r2) higher than 0.9948. LOD ranged from 1.83 to 12.63 μg/kg, and LOQ ranged from 5.49 to 37.89 μg/kg. Average recoveries for the target mycotoxins at three spiked levels ranged from 80.5% to 116.5% with RSD ranging from 2.4% to 10.4%. 23 real aquafeed samples were determined by this method, and 7 kinds of toxins were all detected.

CONCLUSIONS

Obtained results showed that developed method could be successfully applied for the simultaneous determination of mycotoxins in aquatic feeds.

Cytogenotoxic evaluation of the acetonitrile extract, citrinin and dicitrinin-A from Penicillium citrinum

Endophytic fungi are promising sources of bioactive substances; however, their secondary metabolites are toxic to plants, animals, and humans. This study aimed toevaluate the toxic, cytotoxic, mutagenic and oxidant/antioxidant activities of acetonitrile extract (AEPc), citrinin (CIT) and dicitrinin-A (DIC-A) of Penicillium citrinum. For this, the test substances at 0.5; 1.0; 1.5 and 2 μg/mLwere exposed for 24 and 48 h in Artemia salina, and 48 h in Allium cepa test systems. The oxidant/antioxidant test was evaluated in pre-, co- and post-treatment with the stressor hydrogen peroxide (H₂O₂) in Saccharomyces cerevisiae. The results suggest that the AEPc, CIT and DIC-A at 0.5; 1.0; 1.5 and 2 μg/mL showed toxicity in A. saline, with LC₅₀ (24 h) of 2.03 μg/mL, 1.71 μg/mL and 2.29 μg/mL, and LC₅₀ (48 h) of 0.51 μg/mL, 0.54 μg/mL and 0.54 μg/mL, respectively.In A. cepa, the test substances also exerted cytotoxic and mutagenic effects. The AEPc, CIT and DIC-A at lower concentrations modulated the damage induced by H₂O₂ in the proficient and mutant strains of S. cerevisiae for cytoplasmic and mitochondrial superoxide dismutase. Moreover, the AEPc at 2 μg/mL and CIT at the two highest concentrations did not affect the H₂O₂-induced DNA damage in the test strains. In conclusion, AEPc, CIT and DIC-A of P. citrinum may exert their toxic, cytotoxic and mutagenic effects in the test systems possibly through oxidative stress induction pathway.

In vitro Anti-Inflammatory and Anti-Oxidative Stress Activities of Kushenol C Isolated from the Roots of Sophora flavescens

Kushenol C (KC) is a prenylated flavonoid isolated from the roots of Sophoraflavescens aiton. Little is known about its anti-inflammatory and anti-oxidative stress activities. Here, we investigated the anti-inflammatory and anti-oxidative stress effects of KC in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages, and tert-butyl hydroperoxide (tBHP)-induced oxidative stress in HaCaT cells. The results demonstrated that KC dose-dependently suppressed the production of inflammatory mediators, including NO, PGE₂, IL-6, IL1β, MCP-1, and IFN-β in LPS-stimulated RAW264.7 macrophages. The study demonstrated that the inhibition of STAT1, STAT6, and NF-κB activations by KC might have been responsible for the inhibition of NO, PGE₂, IL-6, IL1β, MCP-1, and IFN-β in the LPS-stimulated RAW264.7 macrophages. KC also upregulated the expression of HO-1 and its activities in the LPS-stimulated RAW264.7 macrophages. The upregulation of Nrf2 transcription activities by KC in the LPS-stimulated RAW264.7 macrophages was demonstrated to be responsible for the upregulation of HO-1 expression and its activity in LPS-stimulated RAW264.7 macrophages. In HaCaT cells, KC prevented DNA damage and cell death by upregulating the endogenous antioxidant defense system involving glutathione, superoxide dismutase, and catalase, which prevented reactive oxygen species production from tert-butyl hydroperoxide (tBHP)-induced oxidative stress in HaCaT cells. The upregulated activation of Nrf2 and Akt in the PI3K-Akt signaling pathway by KC was demonstrated to be responsible for the anti-oxidative stress activity of KC in HaCaT cells. Collectively, the study suggests that KC can be further investigated as a potential anti-inflammatory candidate for the treatment of inflammatory diseases.

A Subset of New Platinum Antitumor Agents Kills Cells by a Multimodal Mechanism of Action Also Involving Changes in the Organization of the Microtubule Cytoskeleton

The substitution inert platinum agent [Pt(1 S,2 S-diaminocyclohexane)(5,6-dimethyl-1,10-phenanthroline)]²⁺ (56MeSS, 5) is a potent cytotoxic metallodrug. In contrast to conventional cisplatin or oxaliplatin, the mechanism of action (MoA) of 5 is fundamentally different. However, details of the mechanism by which the 5,6-dimethyl-1,10-phenanthroline ligand contributes to the cytotoxicity of 5 and its derivatives have not been sufficiently clarified so far. Here, we show that 5 and its Pt(IV) derivatives exhibit an intriguing potency in the triple-negative breast cancer cells MDA-MB-231. Moreover, we show that the Pt(IV) derivatives of 5 act by multimodal MoA resulting in the global biological effects, that is, they damage nuclear DNA, reduce the mitochondrial membrane potential, induce the epigenetic processes, and last but not least, the data provide evidence that changes in the organization of cytoskeleton networks are functionally important for 5 and its derivatives, in contrast to clinically used platinum cytostatics, to kill cancer cells.

Molecular signatures of cytotoxic effects in human embryonic kidney 293 cells treated with single and mixture of ochratoxin A and citrinin

Ochratoxin A (OTA) and citrinin (CTN) are important mycotoxins, which often coexist in food and feed stuff. In this study, individual and combinative cytotoxicity of OTA and CTN were tested in human embryonic kidney (HEK) 293 cells via MTT assay, and synergistic cytotoxic effects were found following co-treatment with OTA and CTN, manifested by significant accumulation of HEK293 cells in S and G2/M stages. Transcriptomic and sRNA sequencing were performed to explore molecular signatures mediating individual or combinative cytotoxicity. A total of 378 miRNAs were identified, among which 66 miRNAs targeting thousands of genes were differentially expressed in response to different treatments, and 120 differentially expressed genes (DEGs) were regulated by either individual or combinative treatments. Correlations between two representative miRNAs (hsa-miR-1-3p and hsa-miR-122-5p), and their target genes, programmed cell death 10 (PDCD10) and cyclin G1 (CCNG1), associated with apoptotic signaling and cell cycle were analyzed by luciferase assay system. Further, their expression patterns were validated by quantitative real-time PCR and western blot analysis, suggesting that both miRNA-target interactions might account for the mycotoxin-induced cell death. Taken together, these findings provide molecular evidences for synergistic cytotoxic effects of exposure to single and mixture of OTA and CTN in HEK293 cells.

Comparative evaluation of new dihydropyrimidine and dihydropyridine derivatives perturbing mitotic spindle formation

AIM

The mitotic spindle plays a key role in cell division which makes it an important target in cancer therapy. In the present study the antiproliferative activity of 4-benzyl-5-phenyl-3,4-dihydropyrimidine-2(1H)-thione (1) and its pyridine bioisoster (2) were evaluated and compared with monastrol (MON), the first known cell-permeable small molecule which disrupts bipolar spindle formation by inhibiting Eg5-kinesin activity.

RESULTS

Our data revealed that compound 2 showed higher antiproliferative activity than MON against MCF7 and A375 cell lines and comparable reversible cell cycle inhibition in G2/M phase. However, compound 2 produced distinct phenotype from monoastral spindles, and did not affect Eg5 ATPase activity.

CONCLUSION

The activity of compound 2 may suggest its new promising anticancer mechanism (different than MON), targeting other component required for spindle bipolarity.

Polyhydroxybutyrate-co-hydroxyvalerate copolymer modified graphite oxide based 3D scaffold for tissue engineering application

In this study, we have fabricated the PHBV functionalized graphite oxide using freeze drying technique, followed by 'in situ' pay loading of Fe₃O₄ nanoparticles onto the hydrophobic plate of the composite basal plane; thereby, mechanically and thermally stable, bio-imaging Fe₃O₄/GO-g-PHBV composites have been developed. The synthesis of Fe₃O₄/GO-g-PHBV composite was confirmed by field emission SEM and TEM analyses, X-ray diffraction and Fourier transform infrared spectroscopy. The wrapping of PHBV copolymer into the graphene layers was investigated by atomic force microscopy and Raman spectral analyses which provided the shifting of the 2D band with low signal intensity in the range of 2600-3000 cm^-1. The bactericidal activities of the Fe₃O₄/GO-g-PHBV composite films were found to exhibit more efficiency against Gram-negative bacteria strains compared to Gram-positive strains. In vibrating sample magnetometer (VSM) analysis, the zero value of coercivity revealed the super-paramagnetic nature of the Fe₃O₄/GO-g-PHBV composites. The Phantom agar magnetic resonance imaging analysis revealed the efficiency of Fe₃O₄ nanoparticles as a negative contrast (T₂ contrast) along with higher relaxivity value. The significant fibroblast cell (NIH 3T3) adhesion and proliferation (85%) on the Fe₃O₄/GO-g-PHBV composite surface indicated the physiological and biocompatible stability of that composite along with the presence of large π conjugated aromatic domain.

The prolyl isomerase FKBP25 regulates microtubule polymerization impacting cell cycle progression and genomic stability

FK506 binding proteins (FKBPs) catalyze the interconversion of cis-trans proline conformers in proteins. Importantly, FK506 drugs have anti-cancer and neuroprotective properties, but the effectors and mechanisms underpinning these properties are not well understood because the cellular function(s) of most FKBP proteins are unclear. FKBP25 is a nuclear prolyl isomerase that interacts directly with nucleic acids and is associated with several DNA/RNA binding proteins. Here, we show the catalytic FKBP domain binds microtubules (MTs) directly to promote their polymerization and stabilize the MT network. Furthermore, FKBP25 associates with the mitotic spindle and regulates entry into mitosis. This interaction is important for mitotic spindle dynamics, as we observe increased chromosome instability in FKBP25 knockdown cells. Finally, we provide evidence that FKBP25 association with chromatin is cell-cycle regulated by Protein Kinase C phosphorylation. This disrupts FKBP25-DNA contacts during mitosis while maintaining its interaction with the spindle apparatus. Collectively, these data support a model where FKBP25 association with chromatin and MTs is carefully choreographed to ensure faithful genome duplication. Additionally, they highlight that FKBP25 is a MT-associated FK506 receptor and potential therapeutic target in MT-associated diseases.

The molecular mechanism of G2M cell cycle arrest induced by AFB1 in the jejunum

Aflatoxin B1 (AFB1) has potent hepatotoxic, carcinogenic, genotoxic, immunotoxic and other adverse effects in human and animals. The aim of this study was to investigate the molecular mechanism of G2/M cell cycle arrest induced by AFB1 in the jejunum of broilers. Broilers, as experimental animals, were fed 0.6 mg/kg AFB1 diet for 3 weeks. Our results showed that AFB1 reduced the jejunal villus height, villus height/crypt ratio and caused G2/M cell cycle arrest. The G2/M cell cycle was accompanied by the increase of ataxia telangiectasia mutated (ATM), p53, Chk2, p21 protein and mRNA expression, and the decrease of Mdm2, cdc25C, cdc2, cyclin B and proliferating cell nuclear antigen protein and mRNA expression. In conclusion, AFB1 blocked G2/M cell cycle by ATM pathway in the jejunum of broilers.

Pelargonidin Modulates Keap1/Nrf2 Pathway Gene Expression and Ameliorates Citrinin-Induced Oxidative Stress in HepG2 Cells

Pelargonidin chloride (PC) is one of the major anthocyanin found in berries, radish and other natural foods. Many natural chemopreventive compounds have been shown to be potent inducers of phase II detoxification genes and its up-regulation is important for oxidative stress related disorders. In the present study, we investigated the effect of PC in ameliorating citrinin (CTN) induced cytotoxicity and oxidative stress. The cytotoxicity of CTN was evaluated by treating HepG2 (Human hepatocellular carcinoma) cells with CTN (0–150 μM) in a dose dependent manner for 24 h, and the IC₅₀ was determined to be 96.16 μM. CTN increased lactate dehydrogenase leakage (59%), elevated reactive oxygen species (2.5-fold), depolarized mitochondrial membrane potential as confirmed by JC-1 monomers and arrested cell cycle at G2/M phase. Further, apoptotic and necrotic analysis revealed significant changes followed by DNA damage. To overcome these toxicological effects, PC was pretreated for 2 h followed by CTN exposure for 24 h. Pretreatment with PC resulted in significant increase in cell viability (84.5%), restored membrane integrity, reactive oxygen species level were maintained and cell cycle phases were normal. PC significantly up-regulated the activity of detoxification enzymes: heme oxygenase 1 (HO-1), glutathione transferase, glutathione peroxidase, superoxide dismutase and quinone reductase. Nrf2 translocation into the nucleus was also observed by immunocytochemistry analysis. These data demonstrate the protective effect of PC against CTN-induced oxidative stress in HepG2 cells and up-regulated the activity of detoxification enzyme levels through Keap1/Nrf2 signaling pathway.

A comprehensive review on biological properties of citrinin

Citrinin (CIT) is a mycotoxin which causes contamination in the food and is associated with different toxic effects. A web search on CIT has been conducted covering the timespan since 1946. The accumulated data indicate that CIT is produced by several fungal strains belonging to Penicillium, Aspergillus and Monascus genera, and is usually found together with another nephrotoxic mycotoxin, ochratoxin A. Although, it is evident that CIT exposure can exert toxic effects on the heart, liver, kidney, as well as reproductive system, the mechanism of CIT-induced toxicity remains largely elusive. It is still controversial what are the genotoxic and mutagenic effects of CIT. Until now, its toxic effect has been linked to the CIT-mediated oxidative stress and mitochondrial dysfunction in biological systems. However, the toxicity strongly depends on its concentration, route, frequency and time of exposure, as well as from the used test systems. Besides the toxic effects, CIT is also reported to possess a broad spectrum of bioactivities, including antibacterial, antifungal, and potential anticancer and neuro-protective effects in vitro. This systematic review presents the current state of CIT research with emphasis on its bioactivity profile.

Cytoprotective propensity of green tea polyphenols against citrinin-induced skeletal-myotube damage in C2C12 cells

The mycotoxin citrinin, is produced by several species of Penicillium, Aspergillus and Monascus, and is capable of inducing cytotoxicity, oxidative stress and apoptosis. The aim of the present study was to investigate the effect of citrinin in mouse skeletal muscle cells (C2C12) and to overcome the cellular adverse effects by supplementing green tea extract (GTE) rich in polyphenols. C2C12 myoblasts were differentiated to myotubes and were exposed to citrinin in a dose dependent manner (0-100 µM) for 24 h and IC₅₀ value was found to be 100 µM that resulted in decreased cell viability, increased LDH leakage and compromised membrane integrity. Mitochondrial membrane potential loss, increased accumulation of intracellular ROS and sub G1 phase of cell cycle was observed. To ameliorate the cytotoxic effects of CTN, C2C12 cells were pretreated with GTE (20, 40, 80 µg/ml) for 2 h followed by citrinin (100 µM) treatment for 24 h. GTE pretreatment combated citrinin-induced cytotoxicity and oxidative stress. GTE at 40 and 80 µg/ml significantly promoted cell survival and upregulated antioxidant enzyme activities (CAT, SOD, GPx) and endogenous antioxidant GSH, while the gene and protein expression levels were significantly restored through its effective antioxidant mechanism. Present study results suggested the antioxidant properties of GTE as a herbal source in ameliorating the citrinin-induced oxidative stress.

Determination of 16 mycotoxins in vegetable oils using a QuEChERS method combined with high-performance liquid chromatography-tandem mass spectrometry

A simple and efficient method for determining multiple mycotoxins was developed using a QuEChERS (quick, easy, cheap, effective, rugged and safe)-based extraction procedure in vegetable oils. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used for the quantification and confirmation of 16 chemically diversified mycotoxins. Different extraction procedures were studied and optimised by spiking 16 analytes into blank matrix, and the extraction with 85% MeCN solution and C18 as cleaning sorbent allowed an efficient recovery of 72.8-105.8% with RSDs less than 7%. The limit of detection (LOD) ranged from 0.04 to 2.9 ng g^-1. The developed method was finally applied to screen mycotoxins in 62 vegetable oil samples. Zearalenone (ZEN), aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and α-zearalenol (α-ZOL) were detected, with maximum concentrations of 0.59 (AFG1)-42.5 (ZEN) ng g^-1. The method developed has the advantages of high sensitivity, accuracy and selectivity, and it can be applied to the target screening of mycotoxins in real samples.

Oxidative Stress and Inflammation: What Polyphenols Can Do for Us?

Oxidative stress is viewed as an imbalance between the production of reactive oxygen species (ROS) and their elimination by protective mechanisms, which can lead to chronic inflammation. Oxidative stress can activate a variety of transcription factors, which lead to the differential expression of some genes involved in inflammatory pathways. The inflammation triggered by oxidative stress is the cause of many chronic diseases. Polyphenols have been proposed to be useful as adjuvant therapy for their potential anti-inflammatory effect, associated with antioxidant activity, and inhibition of enzymes involved in the production of eicosanoids. This review aims at exploring the properties of polyphenols in anti-inflammation and oxidation and the mechanisms of polyphenols inhibiting molecular signaling pathways which are activated by oxidative stress, as well as the possible roles of polyphenols in inflammation-mediated chronic disorders. Such data can be helpful for the development of future antioxidant therapeutics and new anti-inflammatory drugs.

Interaction of Citrinin with Human Serum Albumin

Citrinin (CIT) is a mycotoxin produced by several Aspergillus, Penicillium, and Monascus species. CIT occurs worldwide in different foods and drinks and causes health problems for humans and animals. Human serum albumin (HSA) is the most abundant plasma protein in human circulation. Albumin forms stable complexes with many drugs and xenobiotics; therefore, HSA commonly plays important role in the pharmacokinetics or toxicokinetics of numerous compounds. However, the interaction of CIT with HSA is poorly characterized yet. In this study, the complex formation of CIT with HSA was investigated using fluorescence spectroscopy and ultrafiltration techniques. For the deeper understanding of the interaction, thermodynamic, and molecular modeling studies were performed as well. Our results suggest that CIT forms stable complex with HSA (logK ~ 5.3) and its primary binding site is located in subdomain IIA (Sudlow’s Site I). In vitro cell experiments also recommend that CIT-HSA interaction may have biological relevance. Finally, the complex formations of CIT with bovine, porcine, and rat serum albumin were investigated, in order to test the potential species differences of CIT-albumin interactions.

LG308, a Novel Synthetic Compound with Antimicrotubule Activity in Prostate Cancer Cells, Exerts Effective Antitumor Activity

Microtubule plays many different essential roles in the process of tumorigenesis in many eukaryotes, and targeting mitotic progression by disturbing microtubule dynamics is used as a common strategy for cancer treatment. Microtubule-targeted drugs, including paclitaxel and Vinca alkaloids, were previously considered to work primarily by increasing or decreasing the cellular microtubule mass. The tubulin/microtubule system, which is an integral component of the cytoskeleton, is a therapeutic target for prostate cancer. In this study, we found a novel synthetic compound, 8-fluoro-N-phenylacetyl-1, 3, 4, 9-tetrahydro-β-carboline (LG308), which disrupted the microtubule organization via inhibiting the polymerization of microtubule in PC-3M and LNCaP prostate cancer cell lines. Further study proved that LG308 induced mitotic phase arrest and inhibited G2/M progression significantly in LNCaP and PC-3M cell lines in a dose-dependent manner, and these were associated with the upregulation of cyclin B1 and mitotic marker MPM-2 and the dephosphorylation of cdc2. Besides, the cell proliferation and colony formation of PC-3M and LNCaP cells were effectively inhibited by LG308. Furthermore, LG308 induced apoptosis and cell death in PC-3M and LNCaP cell lines in vitro. In vivo, LG308 dramatically suppressed the growth and metastasis of prostate cancer in both xenograft and orthotopic models. All these data indicate that LG308 is a promising anticancer candidate with antimitotic activity for the treatment of prostate cancer.

Hepatotoxic effect of ochratoxin A and citrinin, alone and in combination, and protective effect of vitamin E: In vitro study in HepG2 cell

Ochratoxin A (OTA) and citrinin (CTN) are the most commonly co-occurring mycotoxins in a wide variety of food and feed commodities. The major target organ of these toxins is kidney but liver could also be a target organ. The combined toxicity of these two toxins in kidney cells has been studied but not in liver cell. In this study HepG2 cells were exposed to OTA and CTN, alone and in combination, with a view to compare the molecular and cellular mechanisms underlying OTA, CTN and OTA + CTN hepatotoxicity. OTA and CTN alone as well as in combination affected the viability of HepG2 cells in a dose-dependent manner. OTA + CTN, at a dose of 20% of IC50 of each, produced effect almost similar to that produced by either of the toxins at its IC50 concentration, indicating that the two toxins in combination act synergistically. The cytotoxicity of OTA + CTN on hepatocytes is mediated by increased level of intracellular ROS followed/accompanied by DNA strand breaks and mitochondria-mediated intrinsic apoptosis. Co-treatment of vitamin E (Vit E) with OTA, CTN and OTA + CTN reduced the levels of ROS and the cytotoxicity. But the genotoxic effect of OTA and OTA + CTN was not completely alleviated by Vit E treatment whereas the DNA damage as caused by CTN when treated alone was obviated, indicating that OTA induces DNA damage directly whereas CTN induces ROS-mediated DNA damage and OTA + CTN combination induces DNA damage not exclusively relying on but influenced by ROS generation. Taken together, these findings indicate that OTA and CTN in combination affect hepatocytes at very low concentrations and, thereby, pose a potential threat to public and animal health.

Combretastatin A-4 derived imidazoles show cytotoxic, antivascular, and antimetastatic effects based on cytoskeletal reorganisation

INTRODUCTION

Combretastatin A-4 (CA-4) is a natural cis-stilbene which interferes with the cellular tubulin dynamics and which selectively destroys tumour blood vessels. Its pharmacological shortcomings such as insufficient chemical stability, water solubility, and cytotoxicity can be remedied by employing its imidazole derivatives.

METHODS

We studied 11 halogenated imidazole derivatives of CA-4 for their effects on the microtubule and actin cytoskeletons of cancer and endothelial cells and on the propensity of these cells to migrate across tissue barriers or to form blood vessel-like tubular structures.

RESULTS

A series of N-methyl-4-aryl-5-(4-ethoxyphenyl)-imidazoles proved far more efficacious than the lead CA-4 in growth inhibition assays against CA-4-resistant HT-29 colon carcinoma cells and generally more selective for cancer over nonmalignant cells. Et-brimamin (6), the most active compound, inhibited the growth of various cancer cell lines with IC50 (72 h) values in the low nanomolar range. Active imidazoles such as 6 reduced the motility and invasiveness of cancer cells by initiating the formation of actin stress fibres and focal adhesions as a response to the extensive microtubule disruption. The antimetastatic properties were ascertained in 3D-transwell migration assays which simulated the transgression of highly invasive melanoma cells through the extracellular matrix of solid tumours and through the endothelium of blood vessels. The studied imidazoles exhibited vascular-disrupting effects also against tumour xenografts that are refractory to CA-4. They were also less toxic and better tolerated by mice.

CONCLUSIONS

We deem the new imidazoles promising drug candidates for combination regimens with antiangiogenic VEGFR inhibitors.

DNA damage and S phase arrest induced by Ochratoxin A in human embryonic kidney cells (HEK 293)

Ochratoxin A (OTA) is a ubiquitous mycotoxin with potential nephrotoxic, hepatotoxic and immunotoxic effects. The mechanisms underlying the nephrotoxicity of OTA remain obscure. To investigate DNA damage and the changes of the cell cycle distribution induced by OTA, human embryonic kidney cells (HEK 293 cells) were incubated with various concentrations of OTA for 24h in vitro. The results indicated that OTA treatment led to the production of reactive oxygen species (ROS) and to a decrease of the mitochondrial membrane potential (ΔΨm). OTA-induced DNA damage in HEK 293 cells was evidenced by DNA comet tails formation and increased expression of γ-H2AX. In addition, OTA could induce cell cycle arrest at the S phase in HEK 293 cells. The expression of key cell cycle regulatory factors that were critical to the S phase, including cyclin A2, cyclin E1, and CDK2, were further detected. The expression of cyclin A2, cyclin E1, and CDK2 were significantly decreased by OTA treatment at both the mRNA and protein levels. The apoptosis of HEK 293 cells after OTA treatment was observed using Hoechst 33342 staining. The results confirmed that OTA did induce apoptosis in HEK 293 cells. In conclusion, our results provided new insights into the molecular mechanisms by which OTA might promote nephrotoxicity.

Toxicity of the mycotoxin citrinin and its metabolite dihydrocitrinone and of mixtures of citrinin and ochratoxin A in vitro

Citrinin (CIT) and ochratoxin A (OTA) are mycotoxins produced by several species of the genera Aspergillus, Penicillium and Monascus. Both can be present as contaminants in various food commodities and in animal feed. The occurrence and toxicity of OTA and human exposure have been intensively studied, but for CIT such data are scarce by comparison. Recently, dihydrocitrinone (DH-CIT) was detected as main metabolite of CIT in human urine, and co-occurrence of CIT and OTA was shown in human blood plasma (Blaszkewicz et al. in Arch Toxicol 87:1087-1094, 2013). In light of these new findings, we have now investigated the toxicity of the metabolite DH-CIT in comparison with CIT and analysed the effects of mixtures of CIT and OTA in vitro. The cytotoxic potency of DH-CIT (IC50 of 320/200 μM) was distinctly lower compared with CIT (IC50 of 70/62 μM) after treatment of V79 cells for 24 and 48 h. Whereas CIT induced a concentration-dependent increase in micronucleus frequencies at concentrations ≥30 μM, DH-CIT showed no genotoxic effect up to 300 μM. Thus, conversion of CIT to DH-CIT in humans can be regarded as a detoxification step. Mixtures of CIT and OTA exerted additive effects in cytotoxicity assays. The effect of CIT and OTA mixtures on induction of micronuclei varied dependent on the used concentrations between additive for low μM concentrations and more-than-additive for high μM concentrations. Effects on cell cycle were mostly triggered by OTA when both mycotoxins were used in combination. The implications of our and related in vitro studies are discussed with respect to in vivo concentrations of CIT and OTA, which are found in animals and in humans.

Mycotoxins' activity at toxic and sub-toxic concentrations: differential cytotoxic and genotoxic effects of single and combined administration of sterigmatocystin, ochratoxin A and citrinin on the hepatocellular cancer cell line Hep3B

Food safety organizations indicate the likelihood of constant human and animal exposure to mycotoxin mixtures as a possible negative public health impact. Risk assessment demonstrates that certain mycotoxins of Aspergillus and Penicillium spp. are toxic and hold a significant genotoxic efficacy at nanomolar concentrations. The aim of the current study was to investigate the potential cytogenetic effects of sterigmatocystin (STER), ochratoxin A (OTA) and citrinin (CTN) alone or in combination, at pM to μΜ concentrations, on the human hepatocellular cancer cell line Hep3B. MTT reduction, mitotic divisions, cell cycle delays and sister chromatid exchange rates (SCE) were determined as endpoints of metabolic activity, cytotoxicity, cytostaticity, and genotoxicity, respectively. All mycotoxin treatments induce SCE rates from 10-12 M, while their cytotoxic and cytostatic potential varies. In PRI and MI assays, but not at MTT, STER alone or in combination with OTA + CTN appeared cytostatic and cytotoxic, even at 10-12 M, while CTN alone and all other combinations displayed substantial cellular survival inhibition in doses ≥ 10-8 M. Co-administration of STER + OTA or STER + CTN in concentrations ≤ 10-1 M, increased the MI and MTT activity, while it did not affect the PRI. Mycotoxin co-treatments revealed in general similar-to-additive or antagonistic genotoxic and cytotoxic effects. Our results for the first time describe that STER alone or in combination with OTA and/or CTN share a cytotoxic and cytogenetic potential even at picoMolar concentrations on human hepatoma cells in vitro.

Patterning human neuronal networks on photolithographically engineered silicon dioxide substrates functionalized with glial analogues

Interfacing neurons with silicon semiconductors is a challenge being tackled through various bioengineering approaches. Such constructs inform our understanding of neuronal coding and learning and ultimately guide us toward creating intelligent neuroprostheses. A fundamental prerequisite is to dictate the spatial organization of neuronal cells. We sought to pattern neurons using photolithographically defined arrays of polymer parylene-C, activated with fetal calf serum. We used a purified human neuronal cell line [Lund human mesencephalic (LUHMES)] to establish whether neurons remain viable when isolated on-chip or whether they require a supporting cell substrate. When cultured in isolation, LUHMES neurons failed to pattern and did not show any morphological signs of differentiation. We therefore sought a cell type with which to prepattern parylene regions, hypothesizing that this cellular template would enable secondary neuronal adhesion and network formation. From a range of cell lines tested, human embryonal kidney (HEK) 293 cells patterned with highest accuracy. LUHMES neurons adhered to pre-established HEK 293 cell clusters and this coculture environment promoted morphological differentiation of neurons. Neurites extended between islands of adherent cell somata, creating an orthogonally arranged neuronal network. HEK 293 cells appear to fulfill a role analogous to glia, dictating cell adhesion, and generating an environment conducive to neuronal survival. We next replaced HEK 293 cells with slower growing glioma-derived precursors. These primary human cells patterned accurately on parylene and provided a similarly effective scaffold for neuronal adhesion. These findings advance the use of this microfabrication-compatible platform for neuronal patterning. © 2013 The Authors. Journal ofBiomedicalMaterials Research Part APublished byWiley Periodicals, Inc.Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1350–1360, 2014.

Middle infrared radiation induces G2/M cell cycle arrest in A549 lung cancer cells

There were studies investigating the effects of broadband infrared radiation (IR) on cancer cell, while the influences of middle-infrared radiation (MIR) are still unknown. In this study, a MIR emitter with emission wavelength band in the 3-5 µm region was developed to irradiate A549 lung adenocarcinoma cells. It was found that MIR exposure inhibited cell proliferation and induced morphological changes by altering the cellular distribution of cytoskeletal components. Using quantitative PCR, we found that MIR promoted the expression levels of ATM (ataxia telangiectasia mutated), ATR (ataxia-telangiectasia and Rad3-related and Rad3-related), TP53 (tumor protein p53), p21 (CDKN1A, cyclin-dependent kinase inhibitor 1A) and GADD45 (growth arrest and DNA-damage inducible), but decreased the expression levels of cyclin B coding genes, CCNB1 and CCNB2, as well as CDK1 (Cyclin-dependent kinase 1). The reduction of protein expression levels of CDC25C, cyclin B1 and the phosphorylation of CDK1 at Thr-161 altogether suggest G(2)/M arrest occurred in A549 cells by MIR. DNA repair foci formation of DNA double-strand breaks (DSB) marker γ-H2AX and sensor 53BP1 was induced by MIR treatment, it implies the MIR induced G(2)/M cell cycle arrest resulted from DSB. This study illustrates a potential role for the use of MIR in lung cancer therapy by initiating DSB and blocking cell cycle progression.