Constitutive active/androstane receptor, peroxisome proliferator-activated receptor α, and cytotoxicity are involved in oxadiazon-induced liver tumor development in mice

The Protective Role of Oleuropein Aglycone against Pesticide-Induced Toxicity in a Human Keratinocytes Cell Model

The extensive use of agricultural pesticides to improve crop quality and yield significantly increased the risk to the public of exposure to small but repeated doses of pesticides over time through various routes, including skin, by increasing the risk of disease outbreaks. Although much work was conducted to reduce the use of pesticides in agriculture, little attention was paid to prevention, which could reduce the toxicity of pesticide exposure by reducing its impact on human health. Extra virgin olive oil (EVOO), a major component of the Mediterranean diet, exerts numerous health-promoting properties, many of which are attributed to oleuropein aglycone (OleA), the deglycosylated form of oleuropein, which is the main polyphenolic component of EVOO. In this work, three pesticides with different physicochemical and biological properties, namely oxadiazon (OXA), imidacloprid (IMID), and glyphosate (GLYPHO), were compared in terms of metabolic activity, mitochondrial function and epigenetic modulation in an in vitro cellular model of human HaCaT keratinocytes to mimic the pathway of dermal exposure. The potential protective effect of OleA against pesticide-induced cellular toxicity was then evaluated in a cell pre-treatment condition. This study showed that sub-lethal doses of OXA and IMID reduced the metabolic activity and mitochondrial functionality of HaCaT cells by inducing oxidative stress and altering intracellular calcium flux and caused epigenetic modification by reducing histone acetylation H3 and H4. GLYPHO, on the other hand, showed no evidence of cellular toxicity at the doses tested. Pretreatment of cells with OleA was able to protect cells from the damaging effects of the pesticides OXA and IMID by maintaining metabolic activity and mitochondrial function at a controlled level and preventing acetylation reduction, particularly of histone H3. In conclusion, the bioactive properties of OleA reported here could be of great pharmaceutical and health interest, as they could be further studied to design new formulations for the prevention of toxicity from exposure to pesticide use.

BALB.NCT-Cpox is a unique mouse model of hereditary coproporphyria

In humans, mutations in the coproporphyrinogen oxidase (CPOX) gene can result in hereditary coproporphyria (HCP), characterized by high levels of coproporphyrin excretion in the urine and feces, as well as acute neurovisceral and chronic cutaneous manifestations. Appropriate animal models for comprehending the precise pathogenesis mechanism of HCP have not been reported that show similarities in terms of gene mutation, reduced CPOX activity, excess coproporphyrin accumulation, and clinical symptoms. As previously discovered, the BALB.NCT-Cpox ^nct mouse carries a hypomorphic mutation in the Cpox gene. Due to the mutation, BALB.NCT-Cpox ^nct had a drastic increase in coproporphyrin in the blood and liver persistently from a young age. In this study, we found that BALB.NCT-Cpox ^nct mice manifested HCP symptoms. Similar to HCP patients, BALB.NCT-Cpox ^nct excreted an excessive amount of coproporphyrin and porphyrin precursors in the urine and displayed neuromuscular symptoms, such as a lack of grip strength and impaired motor coordination. Male BALB.NCT-Cpox ^nct had nonalcoholic steatohepatitis (NASH)-like liver pathology and sclerodermatous skin pathology. A portion of male mice had liver tumors as well, whereas female BALB.NCT-Cpox ^nct lacked these hepatic and cutaneous pathologies. In addition, we discovered that BALB.NCT-Cpox ^nct exhibited microcytic anemia. These results indicate that BALB.NCT-Cpox ^nct mice serve as the suitable animal model to help gain insight into the pathogenesis and therapy of HCP.

Effect of Pesticides on Peroxisome Proliferator-Activated Receptors (PPARs) and Their Association with Obesity and Diabetes

Obesity and diabetes mellitus are considered the most important diseases of the XXI century. Recently, many epidemiological studies have linked exposure to pesticides to the development of obesity and type 2 diabetes mellitus. The role of pesticides and their possible influence on the development of these diseases was investigated by examining the relationship between these compounds and one of the major nuclear receptor families controlling lipid and carbohydrate metabolism: the peroxisome proliferator-activated receptors (PPARs), PPARα, PPARβ/δ, and PPARγ; this was possible through in silico, in vitro, and in vivo assays. The present review aims to show the effect of pesticides on PPARs and their contribution to the changes in energy metabolism that enable the development of obesity and type 2 diabetes mellitus.

Protective effect of plant compounds in pesticides toxicity

INTRODUCTION

The relationship between pesticide exposure and the occurrence of many chronic diseases, including cancer, is confirmed by literature data.

METHODS

In this review, through the analysis of more than 70 papers, we explore an increase in oxidative stress level caused by exposure to environmental pollutants and the protective effects of plant-origin antioxidants.

RESULTS AND DISCUSSION

One of the molecular mechanisms, by which pesticides affect living organisms is the induction of oxidative stress. However, recently many plant-based dietary ingredients with antioxidant properties have been considered as a chemopreventive substances due to their ability to remove free radicals. Such a food component must meet several conditions: eliminate free radicals, be easily absorbed and function at an appropriate physiological level. Its main function is to maintain the redox balance and minimize the cellular damage caused by ROS. Therefore, it should be active in aqueous solutions and membrane domains. These properties are characteristic for phenolic compounds and selected plant hormones. Phenolic compounds have proven antioxidant properties, while increasing number of compounds from the group of plant hormones with a very diverse chemical structure turn out to act as antioxidants, being potential food ingredients that can eliminate negative effects of pesticides.

Identification of novel lipid biomarkers in xmrk- and Myc-induced models of hepatocellular carcinoma in zebrafish

BACKGROUND

Hepatocellular carcinoma (HCC) is the predominant form of liver cancer and is accompanied by complex dysregulation of lipids. Increasing evidence suggests that particular lipid species are associated with HCC progression. Here, we aimed to identify lipid biomarkers of HCC associated with the induction of two oncogenes, xmrk, a zebrafish homolog of the human epidermal growth factor receptor (EGFR), and Myc, a regulator of EGFR expression during HCC.

METHODS

We induced HCC in transgenic xmrk, Myc, and xmrk/Myc zebrafish models. Liver specimens were histologically analyzed to characterize the HCC stage, Oil-Red-O stained to detect lipids, and liquid chromatography/mass spectrometry analyzed to assign and quantify lipid species. Quantitative real-time polymerase chain reaction was used to measure lipid metabolic gene expression in liver samples. Lipid species data was analyzed using univariate and multivariate logistic modeling to correlate lipid class levels with HCC progression.

RESULTS

We found that induction of xmrk, Myc and xmrk/Myc caused different stages of HCC. Lipid deposition and class levels generally increased during tumor progression, but triglyceride levels decreased. Myc appears to control early HCC stage lipid species levels in double transgenics, whereas xmrk may take over this role in later stages. Lipid metabolic gene expression can be regulated by either xmrk, Myc, or both oncogenes. Our computational models showed that variations in total levels of several lipid classes are associated with HCC progression.

CONCLUSIONS

These data indicate that xmrk and Myc can temporally regulate lipid species that may serve as effective biomarkers of HCC progression.

Utilizing High-Throughput Screening Data, Integrative Toxicological Prioritization Index Score, and Exposure-Activity Ratios for Chemical Prioritization: A Case Study of Endocrine-Active Pesticides in Food Crops

Endocrine-active chemicals can directly act on nuclear receptors and trigger the disturbances of metabolism and a homeostatic system, which are important risk factors for complicating chronic diseases in humans. The endocrine-active potentials of pesticides acting on estrogen, androgen, and thyroid hormone receptors have been extensively evaluated for pesticides; however, the effects on other receptors are less understood. This study aims to comprehensively characterize and prioritize the endocrine-active pesticides using an exposure-activity ratio (EAR) method and toxicological prioritization index (ToxPi). The aggregate exposure assessment of pesticides was performed using a computational exposure model [stochastic human exposure and dose simulation high-throughput model (SHEDS-HT)]. Minimum in vitro point of departure values were converted to human oral equivalent doses via in vitro-to-in vivo extrapolation. The overall endocrine-disrupting potentials of pesticides were evaluated via 76 assays, representing 11 nuclear receptors. EARs and ToxPi scores were then derived to prioritize 79 pesticides in food. This case study demonstrates that EAR profiling can inform the regulatory agencies for a relevant chemical prioritization, which would direct in-depth health risk assessments in the future.

Detrimental effects of 6 months exposure to very low doses of a mixture of six pesticides associated with chronic vitamin deficiency on rats

This study aimed to evaluate the long-term low-dose effects of exposure to a mixture of 6 pesticide active substances (diquat, imazamox, imazethapyr, tepraloxydin, bentazone, acifluorfen) and to elucidate if chronic vitamin deficiency can influence their toxicity. Two hundred Wistar rats were divided in 4 groups: a vitamin-sufficiency control group, a vitamin-deficiency control group, a vitamin sufficiency test group and a vitamin-deficiency test group. The test groups were treated with the aforementioned pesticides at doses 100 times lower than the corresponding NOAEL. After 6 months, ten rats from each group were sacrificed and a complete evaluation of blood and urine biochemistry, biomarkers of oxidative stress, xenobiotic detoxification enzymes and lysosomal enzymes and organ histopathology was performed. The pesticides mixture and vitamin deficiency determined an increase in alkaline phosphatase levels and urinary calcium levels, abnormal serum lipid profile, and a decrease of total blood proteins levels, red blood cells, haematocrit and haemoglobin. The combination of the two stressors up-regulated CYP1A1, CYP1A2, CYP2B1 and GST levels. This study provides a new proof for the need to move forward from single chemical testing to a more complex approach to account for the multitude of stressors that can challenge the setting of real safety levels.

Systems Pharmacology-Based Identification of Mechanisms of Action of Bolbostemma paniculatum for the Treatment of Hepatocellular Carcinoma

Background

Traditional Chinese medicine has widely used Bolbostemma paniculatum to treat diseases, including cancer, but its underlying mechanisms remain unclear. The present study aimed to elucidate the potential pharmacological mechanisms of “Tu Bei Mu” (TBM), the Chinese name for Bolbostemmatis Rhizoma, the dry tuber of B. paniculatum, for the treatment of hepatocellular carcinoma (HCC).

Material/Methods

The active components and putative therapeutic targets of TBM were explored using SwissTargetPrediction, Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), and Search Tool for Interactions of Chemicals (STITCH). The HCC-related target database was built using DrugBank, DisGeNet, Online Mendelian Inheritance in Man (OMIM), and Therapeutic Target Database (TTD). A protein–protein interaction network of the common targets was constructed, based on the matches between TBM potential targets and HCC-related targets, using Cytoscape software. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of the cluster networks were used to elucidate the biological functions of TBM.

Results

Pharmacological network diagrams of the TBM compound-target network and HCC-related target network were successfully constructed. A total of 22 active components, 191 predicted biological targets of TBM, and 3775 HCC-related targets were identified. Through construction of an HCC-related target database and a protein–protein interaction network of the common targets, TBM was predicted to be effective in treating HCC mainly through the PI3K-Akt, HIF-1, p53, and PPAR signaling pathways.

Conclusions

The PI3K/Akt, HIF1, p53, and PPAR pathways may play vital roles in TBM treatment of HCC. Also, the potential anti-cancer effect of TBM on HCC appears to stem from the synergetic effect of multiple targets and mechanisms.

Oxadiazon affects the expression and activity of aldehyde dehydrogenase and acylphosphatase in human striatal precursor cells: A possible role in neurotoxicity

Exposure to herbicides can induce long-term chronic adverse effects such as respiratory diseases, malignancies and neurodegenerative diseases. Oxadiazon, a pre-emergence or early post-emergence herbicide, despite its low acute toxicity, may induce liver cancer and may exert adverse effects on reproductive and on endocrine functions. Unlike other herbicides, there are no indications on neurotoxicity associated with long-term exposure to oxadiazon. Therefore, we have analyzed in primary neuronal precursor cells isolated from human striatal primordium the effects of non-cytotoxic doses of oxadiazon on neuronal cell differentiation and migration, and on the expression and activity of the mitochondrial aldehyde dehydrogenase 2 (ALDH2) and of the acylphosphatase (ACYP). ALDH2 activity protects neurons against neurotoxicity induced by toxic aldehydes during oxidative stress and plays a role in neurodegenerative conditions such as Alzheimer's disease and Parkinson's disease. ACYP is involved in ion transport, cell differentiation, programmed cell death and cancer, and increased levels of ACYP have been revealed in fibroblasts from patients affected by Alzheimer's disease. In this study we demonstrated that non-cytotoxic doses of oxadiazon were able to inhibit neuronal striatal cell migration and FGF2- and BDNF-dependent differentiation towards neuronal phenotype, and to inhibit the expression and activity of ALDH2 and to increase the expression and activity of ACYP2. In addition, we have provided evidence that in human primary neuronal precursor striatal cells the inhibitory effects of oxadiazon on cell migration and differentiation towards neuronal phenotype were achieved through modulation of ACYP2. Taken together, our findings reveal for the first time that oxadiazon could exert neurotoxic effects by impairing differentiative capabilities of primary neuronal cells and indicate that ALDH2 and ACYP2 are relevant molecular targets for the neurotoxic effects of oxadiazon, suggesting a potential role of this herbicide in the onset of neurodegenerative diseases.

β-catenin Mutations Are Not Involved in Early-stage Hepatocarcinogenesis Induced by Protoporphyrinogen Oxidase Inhibitors in Mice

We previously reported the contribution of constitutive androstane receptor (CAR) in cytotoxicity-related hepatocarcinogenesis induced by oxadiazon (OX) or acifluorfen (ACI), two pesticides categorized as protoporphyrinogen oxidase (PROTOX) inhibitors. The molecular characteristics of preneoplastic and neoplastic lesions induced by OX and ACI were immunohistochemically compared to those by phenobarbital (PB), a typical CAR activator, in wild-type (WT) and CAR knockout (CARKO) mice after diethylnitrosamine initiation. We focused on changes in β-catenin and its transcriptional product glutamine synthetase (GS). In PB-promoted foci and adenomas, nuclear accumulation of mutated β-catenin was increased with high frequency. PB treatment also increased the multiplicity and area of GS-positive foci and adenomas in WT mice. No foci and adenomas showed nuclear accumulation of β-catenin and expression of GS in CARKO mice, similar to both genotypes of mice treated with OX and ACI. Interestingly, hepatocellular carcinoma induced in ACI-treated WT mice showed nuclear accumulation of β-catenin and was positive for GS. Our results indicated that β-catenin mutations were not involved in early-stage hepatocarcinogenesis induced by PROTOX inhibitors in mice, although activation of β-catenin and CAR is important in PB-induced tumorigenesis. The significant differences in molecular profiles suggested involvements of multiple mode of actions for hepatocarcinogenesis induced by PROTOX inhibitors.