Low-dose phthalates promote breast cancer stem cell properties via the oncogene ΔNp63α and the Sonic hedgehog pathway

DEHP-mediated oxidative stress leads to impaired testosterone synthesis in Leydig cells through the cAMP/PKA/SF-1/StAR pathway

Leydig cells (LCs) injury is often irreversible upon discovery; hence, early identification of risk factors for injury is crucial. The ubiquitous plasticizer di-2-ethylhexyl phthalate (DEHP) in the environment has been shown to potentially cause damage to LCs. However, the underlying mechanisms remain unclear. The present study utilized scRNA-seq analysis, the advantage of which is the ability to explore the characteristics of various testicular cells, combined with studies in vitro and in vivo, to assay the changes in and damage processes of LCs during DEHP exposure. We found that DEHP disrupted the structure and function of LCs. GO analysis suggested that a series of pathways changed, among which the most significant were the "steroid synthesis" and "oxidative stress" pathways. Moreover, DEHP dramatically changed the manner of interaction between LCs and other cells, and the most significant type was the cell-cell contact, which included NECTIN, APP, CADM, and CD39. In addition, the activity of multiple transcription factors (TFs) decreased after DEHP exposure, and the activity of steroidogenic factor 1 (SF-1, Nr5a1) was the most obviously altered. Next, we found that the LCs region indeed experienced oxidative stress, including increased ROS signals, the decreased SOD activity and T-AOC, and increased concentration of 8-OHdG and MDA content. The testosterone level, as well as the expression of StAR, P450scc, and 3β-HSD, was also reduced. To study the association between testosterone synthesis and oxidative stress, the antioxidants N-acetyl-L-cysteine (NAC) and H2O2 were used, and we found that mono-2-ethylhexyl ester (MEHP, a major biometabolite of DEHP) disrupted testosterone synthesis through the inhibition of the cAMP/PKA/SF-1/StAR pathway by inducing oxidative stress. Our study provides new insights into the role and mechanisms of DEHP in LCs injury.

The role of di-(2-ethylhexyl) phthalate in cancer initiation and progression: Mechanisms and health implications

The increasing prevalence of cancer has been linked to various environmental factors associated with modern industrial and societal advancements. Di-(2-ethylhexyl) phthalate (DEHP), a commonly used plasticizer, is one such environmental contaminant with potential carcinogenic effects. While epidemiological studies have suggested a positive association between DEHP exposure and cancer risk, the specific role of DEHP in cancer initiation and progression requires further clarification. This review systematically examines the relationship between DEHP exposure and cancer, highlighting key mechanisms involved in tumorigenesis. DEHP has been found to influence several critical aspects of cancer biology, including cell proliferation, apoptosis, metastasis, invasion, epithelial-mesenchymal transition, angiogenesis, drug resistance, immune regulation, and cancer stem cell maintenance. These carcinogenic effects are mediated through multiple pathways, such as the PI3K/AKT signaling pathway, estrogen receptor activation, epigenetic modifications, oxidative stress, and inflammation. By elucidating the molecular mechanisms underlying DEHP's role in cancer, this review aims to contribute to the development of targeted prevention and intervention strategies to mitigate the cancer risks associated with DEHP exposure.

The impact of endocrine-disrupting chemicals on stem cells: Mechanisms and implications for human health

Endocrine-disrupting chemicals (EDCs) are compounds, either natural or man-made, that interfere with the normal functioning of the endocrine system. There is increasing evidence that exposure to EDCs can have profound adverse effects on reproduction, metabolic disorders, neurological alterations, and increased risk of hormone-dependent cancer. Stem cells (SCs) are integral to these pathological processes, and it is therefore crucial to understand how EDCs may influence SC functionality. This review examines the literature on different types of EDCs and their effects on various types of SCs, including embryonic, adult, and cancer SCs. Possible molecular mechanisms through which EDCs may influence the phenotype of SCs are also evaluated. Finally, the possible implications of these effects on human health are discussed. The available literature demonstrates that EDCs can influence the biology of SCs in a variety of ways, including by altering hormonal pathways, DNA damage, epigenetic changes, reactive oxygen species production and alterations in the gene expression patterns. These disruptions may lead to a variety of cell fates and diseases later in adulthood including increased risk of endocrine disorders, obesity, infertility, reproductive abnormalities, and cancer. Therefore, the review emphasizes the importance of raising broader awareness regarding the intricate impact of EDCs on human health.

Selenium protects mouse spermatogonia against ivermectin-induced apoptosis by alleviating endoplasmic reticulum stress in vitro

Ivermectin (IVM) is a widely used anthelmintic in human and veterinary medicine. However, the increasing use of IVM raises concerns about its potential harm against non-targeted organisms. This study demonstrates a novel mechanism where IVM triggers apoptosis via endoplasmic reticulum (ER) stress in GC-1 spg in vitro. The inhibitory effects of selenium (Se) against the toxicological mechanism were also explored. IVM dose-dependently induces oxidative stress, dysregulated Ca2+ levels, and intracellular protein aggregation. Increased mitochondria-associated ER membrane (MAM) activity through Glucose-regulated Protein 75 (Grp75) overloads the mitochondria with Ca2+, causing mitochondrial dysfunction. These simultaneous stressors lead to unfolded protein response and apoptosis. Se reverses all these subcellular events by promoting the expression of selenoprotein-encoding genes to maintain the ER and redox homeostasis. The testis-enriched Glutathione Peroxidase 4 (Gpx4) and the testis-specific Selenoprotein V (Selenov) are only upregulated in the IVM and Se co-treatment group, suggesting their potential role in stress response. These findings confirm that toxic doses of IVM lead to programmed cell death in type B spermatogonia through redox imbalance-associated ER stress. This study provides valuable insights into refining male reproductive toxicity evaluation, targeting of ER stress to protect male germ cells, and maintaining male fertility from IVM-induced toxicity.

Exposure to endocrine disruptor DEHP promotes the progression and radiotherapy resistance of pancreatic cancer cells by increasing BMI1 expression and properties of cancer stem cells

Most patients diagnosed with pancreatic cancer are initially at an advanced stage, and radiotherapy resistance impact the effectiveness of treatment. This study aims to investigate the effects of endocrine disruptor Di-(2-ethylhexyl) phthalate (DEHP) on various biological behaviors and the radiotherapy sensitivity of pancreatic cancer cells, as well as its potential mechanisms. Our findings indicate that exposure to DEHP promotes the proliferation of various cancer cells, including those from the lung, breast, pancreas, and liver, in a time- and concentration-dependent manner. Furthermore, DEHP exposure could influence several biological behaviors of pancreatic cancer cells in vivo and vitro. These effects include reducing cell apoptosis, causing G0/G1 phase arrest, increasing migration capacity, enhancing tumorigenicity, elevating the proportion of cancer stem cells (CSCs), and upregulating expression levels of CSCs markers such as CD133 and BMI1. DEHP exposure can also increase radiation resistance, which can be reversed by downregulating BMI1 expression. In summary our research suggests that DEHP exposure can lead to pancreatic cancer progression and radiotherapy resistance, and the mechanism may be related to the upregulation of BMI1 expression, which leads to the increase of CSCs properties.

Unlocking the Therapeutic Potential of Oral Cancer Stem Cell-Derived Exosomes

Oral cancer (OC) presents a significant global health burden with rising incidence rates. Despite advancements in diagnosis and treatments, the survival rate for OC patients, particularly those with advanced or recurrent disease, remains low at approximately 20%. This poor prognosis is often due to a small population of cancer stem cells (CSCs) that are capable of self-renewal and immune evasion, playing pivotal roles in proliferation, tumor initiation, progression, metastasis, and therapy resistance. Exosomes, which are nano-sized extracellular vesicles (EVs), have emerged as crucial mediators of cell-to-cell communication within the tumor microenvironment (TME). These vesicles carry diverse molecules such as DNA, RNA, proteins, lipids, and metabolites, influencing various cellular processes. Emerging evidence suggests that CSC-derived EVs significantly promote tumor progression and metastasis and maintain the balance between CSCs and non-CSCs, which is vital for intracellular communication within the TME of oral cancer. Recent reports indicate that oral cancer stem cell-derived EVs (OCSC-EVs) influence stemness, immune evasion, metastasis, angiogenesis, tumor reoccurrence, and drug resistance. Understanding OCSC-EVs could significantly improve oral cancer diagnosis, prognosis, and therapy. In this mini-review, we explore OCSC-derived exosomes in oral cancer, examining their potential as diagnostic and prognostic biomarkers that reflect CSC characteristics, and delve into their therapeutic implications, emphasizing their roles in tumor progression and therapy resistance. However, despite their promising potential, several challenges remain, including the need to standardize isolation and characterization methods and to elucidate exosome-mediated mechanisms. Thus, a comprehensive understanding of OCSC-EVs could pave the way for innovative therapeutic strategies that have the potential to improve clinical outcomes for OC patients.

Hazard identification of endocrine-disrupting carcinogens (EDCs) in relation to cancers in humans

Endocrine disrupting chemicals or carcinogens have been known for decades for their endocrine signal disruption. Endocrine disrupting chemicals are a serious concern and they have been included in the top priority toxicants and persistent organic pollutants. Therefore, researchers have been working for a long time to understand their mechanisms of interaction in different human organs. Several reports are available about the carcinogen potential of these chemicals. The presented review is an endeavor to understand the hazard identification associated with endocrine disrupting carcinogens in relation to the human body. The paper discusses the major endocrine disrupting carcinogens and their potency for carcinogenesis. It discusses human exposure, route of entry, carcinogenicity and mechanisms. In addition, the paper discusses the research gaps and bottlenecks associated with the research. Moreover, it discusses the limitations associated with the analytical techniques for detection of endocrine disrupting carcinogens.

Environmental monobutyl phthalate exposure promotes liver cancer via reprogrammed cholesterol metabolism and activation of the IRE1α-XBP1s pathway

Humans are widely exposed to phthalates, a major chemical plasticizer that accumulates in the liver. However, little is known about the impact of chronic phthalate exposure on liver cancer development. In this study, we applied a long-term cell culture model by treating the liver cancer cell HepG2 and normal hepatocyte L02 to environmental dosage of monobutyl phthalate (MBP), the main metabolite of phthalates. Interestingly, we found that long-term MBP exposure significantly accelerated the growth of HepG2 cells in vitro and in vivo, but barely altered the function of L02 cells. MBP exposure triggered reprogramming of lipid metabolism in HepG2 cells, where cholesterol accumulation subsequently activated the IRE1α-XBP1s axis of the unfolded protein response. As a result, the XBP1s-regulated gene sets and pathways contributed to the increased aggressiveness of HepG2 cells. In addition, we also showed that MBP-induced cholesterol accumulation fostered an immunosuppressive microenvironment by promoting tumor-associated macrophage polarization toward the M2 type. Together, these results suggest that environmental phthalates exposure may facilitate liver cancer progression, and alerts phthalates exposure to patients who already harbor liver tumors.

Exposure to di-2-ethylhexyl phthalate and breast neoplasm incidence: A cohort study

BACKGROUND

Phthalates are ubiquitous environmental endocrine disruptors. As the predominant phthalate, di-2-ethylhexyl phthalate (DEHP) has been considered possibly carcinogenic to humans but large-scale longitudinal evidence is needed to further clarify its carcinogenicity.

OBJECTIVES

To examine the association between DEHP exposure and incidence of breast malignant neoplasm, carcinoma in situ and benign neoplasm.

METHODS

A total of 273,295 women from UK Biobank cohort were followed up for a median of 13.5 years. Disease information was collected from National Health Service Cancer Registry and National Death Index. Baseline and yearly-average level of DEHP exposure were estimated for each individual by linking chemical monitoring record of European Environment Agency with home address of the participants by Kriging interpolation model. Cox proportional hazard model was employed to estimate the association between DEHP exposure and breast neoplasms.

RESULTS

The median (IQR) of baseline and yearly-average DEHP concentration were 8000.25 (interquartile range: 6657.85-11,948.83) and 8000.25 (interquartile range: 1819.93-11,359.55) μg/L. The highest quartile of baseline DEHP was associated with 1.11 fold risk of carcinoma in situ (95 % CI, 1.00, 1.23, p < 0.001) and 1.27 fold risk of benign neoplasm (95 % CI, 1.05, 1.54, p < 0.001). As for yearly-average exposure, each quartile of DEHP was positively associated with higher risk of malignant neoplasm (HR, 1.05; 95 % CI, 1.03, 1.07, p < 0.001), carcinoma in situ (HR, 1.08; 95 % CI, 1.04, 1.11, p < 0.001) and benign neoplasm (HR, 1.13; 95 % CI, 1.07, 1.20, p < 0.001). Stratification analysis showed no significant modification effects on the DEHP-neoplasm relationship by menopausal status or ethnicity but a suggestive higher risk in younger women and those who underwent oral contraceptive pill therapy. In sensitivity analysis, the associations remained when excluding the cases diagnosed within 2 years post baseline.

CONCLUSIONS

Real-world level of DEHP exposure was associated with higher risk of breast neoplasms. Because of the health risks associated with DEHP, its release to the environment should be managed.

Association between urinary phthalates and phthalate metabolites and cancer risk: A systematic review and meta-analysis

Phthalates, widely utilized in industrial products, are classified as endocrine-disrupting chemicals (EDCs). Although certain phthalate and their metabolites have been implicated in cancer development, the reported findings have exhibited inconsistencies. Therefore, we conducted the comprehensive literature search to assess the association between phthalate and their metabolites and cancer risk by identifying original studies measuring phthalates or their metabolites and reporting their correlation with cancer until July 4, 2023. The Odds Ratios (ORs) and corresponding 95% confidence intervals (CIs) were extracted and analyzed to estimate the risk. Pooled data from eleven studies, including 3101 cancer patients and 6858 controls, were analyzed using a fixed- or random-effects model based on heterogeneity tests. When comparing extreme categories of different phthalates and their metabolites, we observed a significant association between urinary phthalates and phthalate metabolites (MEHHP, MECPP, DBP and MBzP) and cancer risk. The findings of our meta-analysis reinforce the existing evidence that urinary phthalates and phthalate metabolites is strongly associated with cancer development. Further investigations are warranted to elucidate the underlying mechanisms of this association. These results may offer novel insights into cancer development.

Worldwide risk assessment of phthalates and bisphenol A in humans: The need for updating guidelines

Phthalates and bisphenol A (BPA) are compounds widely used as raw materials in the production of plastics, making them ubiquitous in our daily lives. This results in widespread human exposure and human health hazards. Although efforts have been conducted to evaluate the risk of these compounds in diverse regions around the world, data scattering may mask important trends that could be useful for updating current guidelines and regulations. This study offers a comprehensive global assessment of human exposure levels to these chemicals, considering dietary and nondietary ingestion, and evaluates the associated risk. Overall, the exposure daily intake (EDI) values of phthalates and BPA reported worldwide ranged from 1.11 × 10-7 to 3 700 µg kg bw-1 d-1 and from 3.00 × 10-5 to 6.56 µg kg bw-1 d-1, respectively. Nevertheless, the dose-additive effect of phthalates has been shown to increase the EDI up to 5 100 µg kg bw-1 d-1, representing a high risk in terms of noncarcinogenic (HQ) and carcinogenic (CR) effects. The worldwide HQ values of phthalates and BPA ranged from 2.25 × 10-7 to 3.66 and from 2.74 × 10-7 to 9.72 × 10-2, respectively. Meanwhile, a significant number of studies exhibit high CR values for benzyl butyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP). Moreover, DEHP has shown the highest maximum mean CR values for humans in numerous studies, up to 179-fold higher than BBP. Despite mounting evidence of the harmful effects of these chemicals at low-dose exposure on animals and humans, most regulations have not been updated. Thus, this article emphasizes the need for updating guidelines and public policies considering compelling evidence for the adverse effects of low-dose exposure, and it cautions against the use of alternative plasticizers as substitutes for phthalates and BPA because of the significant gaps in their safety.

Mechanisms of breast cancer progression induced by environment-polluting aryl hydrocarbon receptor agonists

Breast cancer is the most common invasive malignancy among women worldwide and constitutes a complex and heterogeneous disease. Interest has recently grown in the role of the aryl hydrocarbon receptor (AhR) in breast cancer and the contribution of environment-polluting AhR agonists. Here, we present a literature review addressing AhR ligands, including pesticides hexachlorobenzene and chlorpyrifos, polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, parabens, and phthalates. The objectives of this review are a) to summarize recent original experimental, preclinical, and clinical studies on the biological mechanisms of AhR agonists which interfere with the regulation of breast endocrine functions, and b) to examine the biological effects of AhR ligands and their impact on breast cancer development and progression. We discuss biological mechanisms of action in cell viability, cell cycle, proliferation, epigenetic changes, epithelial to mesenchymal transition, and cell migration and invasion. In addition, we examine the effects of AhR ligands on angiogenic processes, metastasis, chemoresistance, and stem cell renewal. We conclude that exposure to AhR agonists stimulates pathways that promote breast cancer development and may contribute to tumor progression. Given the massive use of industrial and agricultural chemicals, ongoing evaluation of their effects in laboratory assays and preclinical studies in breast cancer at environmentally relevant doses is deemed essential. Likewise, awareness should be raised in the population regarding the most harmful toxicants to eradicate or minimize their use.