Di(2-ethylhexyl) phthalate inhibits glutathione regeneration and dehydrogenases of the pentose phosphate pathway on human colon carcinoma cells

Association between Biomarkers of Phthalate Exposure and Serum Folate Concentrations in Children: A Population-Based Cross-Sectional Study of the NHANES from 2011 to 2016

BACKGROUND

Although adverse health effects of phthalates have been reported, very few studies have assessed the associations between biomarkers of phthalate exposure and serum folate concentrations in children.

OBJECTIVES

We aimed to examine the association between urinary phthalate metabolites, as biomarkers of exposure to phthalates, and total serum folate concentrations in children using national data from the United States.

METHODS

We conducted cross-sectional analyses of 2100 individuals aged 6-18 y enrolled in the National Health and Nutrition Examination Survey, 2011-2016. Multivariable linear regression was applied to examine the relationship between natural logarithm (ln)-transformed urinary phthalate metabolites and serum folate concentrations. The quantile-based g-computation was used to assess the association of urinary phthalate metabolite mixture with serum folate levels. Subgroup analyses were conducted by sex, age, and race/ethnicity, and the interactions were assessed by adding interaction terms of these stratifying variables and phthalates and modeling through the Wald test.

RESULTS

In multiple linear regression models, for participants in the highest tertile of MEHHP, MEOHP, DEHP, MCPP, and MCOP, total serum folate concentrations were 1.566 [β: -1.566; 95% confidence interval: -2.935, -0.196], 1.423 (-1.423; -2.689, -0.157), 1.309 (-1.309; -2.573, -0.044), 1.530 (-1.530; -2.918, -0.142), and 1.381 (-1.381; -2.641, -0.122) ng/mL lower than those in the lowest tertile. The inverse associations were consistent in different subgroups by sex, age, and race/ethnicity (P for interaction ≥0.083 for all). In addition, the phthalate mixture showed a strong inverse correlation with serum folate; a quartile increase in the phthalate mixture on the ln scale was associated with 0.888 (-0.888; -1.677, -0.099) ng/mL decrease in the serum folate.

CONCLUSIONS

Higher concentrations of urinary phthalate metabolites were associated with lower serum folate concentrations in children. Although our findings should be validated through additional population and mechanistic studies, they support a potential adverse effect of phthalate exposure on folate metabolism in children.

Transcriptome sequencing and metabolite analysis reveal the single and combined effects of microplastics and di-(2-ethylhexyl) phthalate on Peneaus vannamei

Due to the rising usage of plastics, plastic debris are present throughout marine ecosystems and detrimentally affects marine biota. Additionally, plastics likely result in elusive toxicity effects due to addition of plasticizers. The aim of the present study was to reveal the potential effects and mechanism of microplastics (MPs), di-(2-ethylhexyl) phthalate (DEHP) and copollution of MPs and DEHP (MPs-DEHP) on Peneaus vannamei (P. vannamei) juveniles regarding oxidative stress, transcriptomics and metabolomics. MPs, DEHP and MPs-DEHP significantly induced the activities of superoxide dismutase (SOD) and catalase (CAT); MPs and DEHP have an antagonistic effect for malondialdehyde (MDA); suggesting that disorders of the antioxidant defence systems. 13, 133 and 58 differentially expressed genes and 21, 82 and 39 differentially expressed metabolites were responsible for the distinction of MPs, DEHP and MPs-DEHP groups, respectively. The combination of transcriptomic and metabolomic analyses showed that MPs, DEHP and MPs-DEHP exposure disturbed amino acid and lipid metabolism, and further induced inflammatory responses and dysfunction of purine metabolism. Furthermore, the presence of MPs might alleviate the biotoxicity of DEHP in P. vannamei. These findings provide new insights into the single and combined toxicological effects of MPs and additives for marine biota.

Therapeutic efficacy of N-acetylcysteine and zinc sulphate against di-(2-ethylhexyl) phthalate-induced testicular oxido-nitrergic stress in male Wistar rat

The therapeutic efficacy of N-acetylcysteine (NAC) and zinc sulphate on di-(2-ethylhexyl) phthalate (DEHP)-induced testicular oxido-nitrergic stress in rats was investigated in 36 male Wistar rats (170 ± 10 g) randomly assigned into one of six groups (n = 6). Group 1 (control) received 2.5 ml/kg of distilled water for 42 days, while group 2 (vehicle) received 2.5 ml/kg of corn oil for 42 days. Groups 3,4,5, and 6 were administered DEHP (750 mg/kg/day) for 21 days, after which groups 4, 5, and 6 received zinc sulphate (0.5 mg/kg/day), NAC (100 mg/kg/day), and zinc sulphate (0.5 mg/kg/day) + NAC (100 mg/kg/day) for an additional 21 days respectively. After the experimental period, the animals were euthanized by light thiopental sodium, and their testes were carefully dissected out for histological and biochemical assays. The result shows a significant alteration in testicular levels of malondialdehyde, nitric oxide, antioxidant enzymes, total antioxidant capacity, sulphydryl levels, dehydrogenases and testicular architecture following the administration of DEHP. These effects were reversed by coadministration of NAC and zinc sulphate in the study. We therefore concluded that the combined effects of NAC and ZnSO4 effectively improved testicular antioxidant status and reduced testicular nitregic stress, thus improving testicular architecture and functions.

NRF2: A crucial regulator for mitochondrial metabolic shift and prostate cancer progression

Metabolic alterations are a common survival mechanism for prostate cancer progression and therapy resistance. Oxidative stress in the cellular and tumor microenvironment dictates metabolic switching in the cancer cells to adopt, prosper and escape therapeutic stress. Therefore, regulation of oxidative stress in tumor cells and in the tumor-microenvironment may enhance the action of conventional anticancer therapies. NRF2 is the master regulator for oxidative stress management. However, the overall oxidative stress varies with PCa clinical stage, metabolic state and therapy used for the cancer. In agreement, the blanket use of NRF2 inducers or inhibitors along with anticancer therapies cause adverse effects in some preclinical cancer models. In this review, we have summarized the levels of oxidative stress, metabolic preferences and NRF2 activity in the different stages of prostate cancer. We also propose condition specific ways to use NRF2 inducers or inhibitors along with conventional prostate cancer therapies. The significance of this review is not only to provide a detailed understanding of the mechanism of action of NRF2 to regulate oxidative stress-mediated metabolic switching by prostate cancer cells to escape the radiation, chemo, or hormonal therapies, and to grow aggressively, but also to provide a potential therapeutic method to control aggressive prostate cancer growth by stage specific proper use of NRF2 regulators.

Lycopene regulates the mitochondrial unfolded protein response to prevent DEHP-induced cardiac mitochondrial damage in mice

Lycopene (LYC), as a kind of carotene, has antioxidant effects. Di(2-ethylhexyl) phthalate (DEHP) was used to improve the flexibility of plastics. However, the potential role of LYC in DEHP induced cardiac injury in mice remains unclear. Therefore, the aim of this study was to investigate the role and mechanism of LYC in DEHP induced cardiac injury. Male ICR mice were treated with DEHP (500 or 1000 mg per kg BW per day) and/or LYC (5 mg per kg BW per day) for 28 days. The results of histopathology and ultrastructure showed that LYC relieved the decrease of mitochondrial volume density and myocardial fibre disorder induced by DEHP. Subsequently, LYC attenuated DEHP-induced mitochondrial damage, mitochondrial unfolded protein response (UPR^mt) activation, nuclear factor erythroid 2-related factor 2 (Nrf2) mediated oxidative stress and heat shock response (HSR) activation induced by DEHP. LYC regulates UPR^mt to prevent DEHP-induced cardiac mitochondrial damage. Thus, this study provided new evidence of UPR^mt as a target for LYC treatment preventing DEHP-induced cardiac disease.

Mechanistic insights into primary biotransformation of diethyl phthalate in earthworm and significant SOD inhibitory effect of esterolytic products

Phthalic acid esters (PAEs) are used as plasticizer or modifier in artificially-manufactured products. Though the rapid biotransformation of phthalates in microbes and plants have been well documented, it is less studied yet in terrestrial animals, e.g. earthworm. In this study, the major biotransformation of diethyl phthalate (DEP) in Eisenia fetida was illustrated using in vitro incubation of earthworm crude enzymes. DEP could be substantially biotransformed into phthalate monoester (MEP) and a small amount of phthalic acid (PA) through esterolysis, which was verified to be driven by endogenous carboxylesterase. Despite the inferior contribution, the oxidation of DEP might also occur under the initiated electron transfer by NADPH coenzyme. The dominant metabolite MEP showed a higher inhibition of superoxide dismutase (SOD) activity than DEP with EC₅₀ of 0.0082 ± 0.0016 mmol/L, so the higher ecological risks of MEP would be marked. The inhibition effect of PA was validated to be even stronger than MEP though it was slightly generated. The direct binding interaction with SOD was proved to be an important molecular event for regulation of SOD activity. Besides the static quenching mechanism, the caused conformational changes including despiralization of α-helix and spatial reorientation of tryptophan were spectrally believed to affect binding and underlie inhibition efficiency of SOD activity.

Glucose-6-phosphate dehydrogenase promotes the proliferation and migration of lung adenocarcinoma cells via the STAT3 signaling pathway

Lung adenocarcinoma (LUAD) is the most common histological subtype of lung cancer, and the leading cause of cancer-related deaths worldwide. G6PD has been reported to enhance the progression of various tumors by regulating the intracellular redox state and mediating nucleic acid synthesis. However, the biological role and molecular mechanism of G6PD in LUAD remain largely unknown. In this study, we found that G6PD was significantly upregulated in LUAD specimens and cell lines, and that the high levels of G6PD expression were closely associated with a poor prognosis for LUAD patients. Moreover, we found that G6PD significantly promoted the proliferation and migration of LUAD cells in vitro, and overexpression of G6PD also play a role of facilitating tumorigenesis in in vivo experiments. Mechanistically, the STAT3 signaling pathway was significantly activated by G6PD-mediated LUAD progression. Overall, our results suggest that G6PD could serve as a novel prognostic marker and therapeutic target for treating LUAD.

Lineage-Selective Disturbance of Early Human Hematopoietic Progenitor Cell Differentiation by the Commonly Used Plasticizer Di-2-ethylhexyl Phthalate via Reactive Oxygen Species: Fatty Acid Oxidation Makes the Difference

Exposure to ubiquitous endocrine-disrupting chemicals (EDCs) is a major public health concern. We analyzed the physiological impact of the EDC, di-2-ethylhexyl phthalate (DEHP), and found that its metabolite, mono-2-ethylhexyl phthalate (MEHP), had significant adverse effects on myeloid hematopoiesis at environmentally relevant concentrations. An analysis of the underlying mechanism revealed that MEHP promotes increases in reactive oxygen species (ROS) by reducing the activity of superoxide dismutase in all lineages, possibly via its actions at the aryl hydrocarbon receptor. This leads to a metabolic shift away from glycolysis toward the pentose phosphate pathway and ultimately results in the death of hematopoietic cells that rely on glycolysis for energy production. By contrast, cells that utilize fatty acid oxidation for energy production are not susceptible to this outcome due to their capacity to uncouple ATP production. These responses were also detected in non-hematopoietic cells exposed to alternate inducers of ROS.

Stereological analysis and transcriptome profiling of testicular injury induced by di-(2-ethylhexyl) phthalate in prepubertal rats

Di-(2-ethylhexyl) phthalate (DEHP) is the most common phthalate that can affect the male reproductive system. DEHP exposure at the prepubertal stage could lead to the injury of immature testes, but the mechanism has not been fully clarified. In the present study, we elucidated the possible underlying mechanism of DEHP-induced prepubertal testicular injury through stereological analysis and transcriptome profiling. Compared with the control group, the DEHP-treated rats had lower body weight gain and decreased testicular weight and organ coefficient. Moreover, lower serum levels of testosterone and LH were observed in the DEHP group, in contrast to the increased FSH level. Additionally, the serum level of estradiol had no significant difference after DEHP exposure. Stereological analysis showed significant reduction in volumes of most testicular structures, especially in the seminiferous tubule and seminiferous epithelium, along with a vast decrease of spermatogenic cells and obvious structural damages with substantial pathological signs (germ cracks, cytoplasmic vacuolization, sloughing, multinucleated giant cell formation, chromatolysis desquamation and dissolution, pyknosis of nuclei) in the seminiferous tubule upon DEHP exposure at the prepubertal stage. Furthermore, transcriptome profiling identified 5548 differentially expressed genes (DEGs) upon DEHP exposure. Pathway enrichment analysis revealed several crucial signaling pathways related to retinol metabolism, oxidative phosphorylation, steroid hormone biosynthesis, and cell adhesion molecules (CAMs). In addition, seven DEGs selected from RNA-seq data were validated by quantitative real-time polymerase chain reaction (qRT-PCR), and the results showed the same trends as the RNA-seq results. In conclusion, the above findings provide basic morphological data and lay a foundation for systematic research on transcriptome profiling in prepubertal testicular injury induced by DEHP.

DEHP-induce damage in grass carp hepatocytes and the remedy of Eucalyptol

The wide application of plastic products led to the wide exposure of plasticizer in environment. As a new environmental pollutant, plasticizers' toxicity researches were far from enough in fish. In order to further explore these mechanisms, we used Diethylhexyl phthalate (DEHP), a common plasticizer, treated the grass carp hepatocytes, and selected Eucalyptol (EUC) to study its antagonistic effect on DEHP. The results showed that after DEHP exposure, oxidative stress level and inflammation in grass carp hepatocytes were increased, and then mRNA and protein expression of apoptosis related markers were increased significantly, leading to hepatocytes apoptosis. Moreover, AO/EB staining and Hoethst staining also showed that the number of apoptotic cells increased after DEHP exposure. It should be noted that both EUC pretreatment and EUC simultaneous treatment could alleviate the oxidative stress, levels of inflammatory factors and apoptosis induced by DEHP. In comparison, the effect of EUC simultaneous treatment was better. Our results showed that DEHP induced apoptosis in grass carp hepatocytes through oxidative stress and inflammation, while EUC could alleviate apoptosis by reducing oxidative stress and inflammation caused by DEHP. The innovation of this study was to explore the interaction between DEHP and EUC for the first time. This study found that DEHP could cause apoptosis in grass carp hepatocytes through oxidative stress and inflammation; EUC had a good antagonistic effect on a series of damage in grass carp hepatocytes caused by DEHP, and EUC pretreatment and simultaneous treatment had a certain effect, among which, simultaneous treatment had a better effect. This study enriched the theoretical mechanism of DEHP toxicity in fish hepatocytes, and put forward the methods to solve the toxicity of DEHP.