Low Doses of Methylmercury Induce the Proliferation of Thyroid Cells In Vitro Through Modulation of ERK Pathway

Single and combined effects of increased temperature and methylmercury on different stages of the marine rotifer Brachionus plicatilis

Rapid, anthropogenic activity-induced global warming is a severe problem that not only raises water temperatures but also shifts aquatic environments by increasing the bioavailability of heavy metals (HMs), with potentially complicated effects on aquatic organisms, including small aquatic invertebrates. For this paper, we investigated the combined effects of temperature (23 and 28 °C) and methylmercury (MeHg) by measuring physiological changes, bioaccumulation, oxidative stress, antioxidants, and the mitogen-activated protein kinase signaling pathway in the marine rotifer Brachionus plicatilis. High temperature and MeHg adversely affected the survival rate, lifespan, and population of rotifers, and bioaccumulation, oxidative stress, and biochemical reactions depended on the developmental stage, with neonates showing higher susceptibility than adults. These findings demonstrate that increased temperature enhances potentially toxic effects from MeHg, and susceptibility differs with the developmental stage. This study provides a comprehensive understanding of the combined effects of elevated temperature and MeHg on rotifers. ENVIRONMENTAL IMPLICATION: Methylmercury (MeHg) is a widespread and harmful heavy metal that can induce lethal effects on aquatic organisms in even trace amounts. The toxicity of metals can vary depending on various environmental conditions. In particular, rising temperatures are considered a major factor affecting bioavailability and toxicity by changing the sensitivity of organisms. However, there are few studies on the combinational effects of high temperatures and MeHg on aquatic animals, especially invertebrates. Our research would contribute to understanding the actual responses of aquatic organisms to complex aquatic environments.

Elucidating the link between thyroid cancer and mercury exposure: a review and meta-analysis

Mercury (Hg) is a widely distributed and bioavailable metal of public health concern, with many known human toxicities, but data regarding mercury's influence on thyroid cancer (TC) is scarce. Mercury is known to impact several molecular pathways implicated in carcinogenesis, and its proclivity for bioaccumulation in the thyroid suggests a potential modulatory effect. We conducted a literature/systematic review of studies between 1995-2022 intending to define better and establish relationships between these two entities, congregate the evidence for mercury's potential role in thyroid carcinogenesis, and identify populations of interest for further study. Insufficient evidence precludes definitive conclusions on dietary mercury as a TC risk factor; however, several common mechanisms affected by mercury are crucial for TC development, including biochemical, endocrine, and reactive oxygen species effects. Quantitative analysis revealed associations between TC risk and mercury exposure. In three mercury studies, average urine levels were higher in TC patients, with a mean difference of 1.86 µg/g creatinine (95% CI = 0.32-3.41). In two studies investigating exposure to elevated mercury levels, the exposed group exhibited a higher risk of developing TC, with a relative risk of 1.90 (95% CI = 1.76-2.06). In three thyroid tissue studies, mercury levels (ppm) were higher in TC patients, averaging 0.14 (0.06-0.22) in cancerous cases (N = 178) and 0.08 (0.04-0.11) in normal thyroids (N = 257). Our findings suggest an association between mercury exposure and TC risk, implying a possible predisposing factor. Further research is necessary to reveal the clinical relevance of dietary and environmental mercury exposures in TC pathogenesis.

The environmental burden on endocrine neoplasia: a review on the documented impact of endocrine disrupting chemicals

INTRODUCTION

Endocrine-disrupting chemicals (EDCs) have gained more importance in the past decade, mostly due to their role in the pathogenesis of disease, especially in carcinogenesis. However, there is limited literature on the environmental burden on some of the less common endocrine neoplasia.

AREAS COVERED

This review focuses on both observational and experimental studies linking exposure to EDCs and endocrine neoplasia specifically pituitary, thyroid, adrenal and neuroendocrine tumors. Following PRISMA guidelines, a search of English peer-reviewed literature was performed using Medline and Google Scholar, giving preference to recent publications.

EXPERT OPINION

Exposure to EDC occurs not only in the household but also at work, whether it is in the office, factory, or farm and during transport from one location to another. Many studies have evaluated the effect of single environmental agents; however, humans are rarely exposed to only one EDC. Different EDCs and different levels of exposure may interact together to provide either a synergistic and/or an antagonistic disruption on human health, and hence a complex mechanism to elucidate. The ultimate adverse effect is difficult to predict, as it is not only influenced by the degree of exposure, but also by genetics, lifestyle, comorbidities, and other stressors.

Association between metal(loid)s in serum and leukemia: a systematic review and meta-analysis

Purpose

Heavy metals and metalloids are recognized as environmental threats, which are considered highly toxic and carcinogenic. Epidemiologically, their association with leukemia is under debate. We aim to clarify the association between the heavy metal(loid)s in serum and leukemia via a systematic review and meta-analysis.

Methods

We searched PubMed, Embase, Google Scholar, and CNKI (China National Knowledge Infrastructure) databases for all related articles. The standardized mean difference and its 95% confidence interval was used to evaluate the association of leukemia with heavy metal(loid)s in serum. The statistical heterogeneity among studies was assessed with the Q-test and I 2 statistics.

Results

Among 4,119 articles related to metal(loid)s and leukemia, 21 studies met our inclusion criteria, which are all cross-sectional studies. These 21 studies involved 1,316 cases and 1,310 controls, based on which we evaluate the association of heavy metals/metalloids in serum with leukemia. Our results indicated positive differences for serum chromium, nickel, and mercury in leukemia patients, while a negative difference for serum manganese in acute lymphocytic leukemia (ALL).

Conclusion

Our results suggested an elevated trend of serum chromium, nickel, and mercury concentrations in leukemia patients while descending trend of serum manganese concentration in ALL patients. The result of sensitivity analysis between lead, cadmium, and leukemia and publication bias of association between chromium and leukemia also needed attention. Future research work may focus on the dose-response relationship between any of these elements and the leukemia risks, and further elucidation of how these elements are related to leukemia may shed light on the prevention and treatment of leukemia.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-023-00853-2.

Antioxidant Supplementation Alleviates Mercury-Induced Cytotoxicity and Restores the Implantation-Related Functions of Primary Human Endometrial Cells

Mercury (Hg) cytotoxicity, which is largely mediated through oxidative stress (OS), can be relieved with antioxidants. Thus, we aimed to study the effects of Hg alone or in combination with 5 nM N-Acetyl-L-cysteine (NAC) on the primary endometrial cells' viability and function. Primary human endometrial epithelial cells (hEnEC) and stromal cells (hEnSC) were isolated from 44 endometrial biopsies obtained from healthy donors. The viability of treated endometrial and JEG-3 trophoblast cells was evaluated via tetrazolium salt metabolism. Cell death and DNA integrity were quantified following annexin V and TUNEL staining, while the reactive oxygen species (ROS) levels were quantified following DCFDA staining. Decidualization was assessed through secreted prolactin and the insulin-like growth factor-binding protein 1 (IGFBP1) in cultured media. JEG-3 spheroids were co-cultured with the hEnEC and decidual hEnSC to assess trophoblast adhesion and outgrowth on the decidual stroma, respectively. Hg compromised cell viability and amplified ROS production in trophoblast and endometrial cells and exacerbated cell death and DNA damage in trophoblast cells, impairing trophoblast adhesion and outgrowth. NAC supplementation significantly restored cell viability, trophoblast adhesion, and outgrowth. As these effects were accompanied by the significant decline in ROS production, our findings originally describe how implantation-related endometrial cell functions are restored in Hg-treated primary human endometrial co-cultures by antioxidant supplementation.

DACH1 inhibits the proliferation and migration of papillary thyroid carcinoma

DACH1 is an important component of the retinal determinate gene network (RDGN), which regulates the expression of target genes by directly binding or interacting with other factors. DACH1 shows inhibitory effects in most tumors, but its role in papillary thyroid carcinoma is unclear and warrants further investigation. We assessed the expression of DACH1 in different tissues and correlation with immune infiltration by The Cancer Genome Atlas (TCGA) and Tumor Immune Estimation Resource (TIMMER2.0 databases). The effects of DACH1 on the proliferation and migration of TPC-1 and Bcpap cells were assessed by cell viability assay, colony formation assay, wound healing assay, transwell migration assay, and flow cytometry. Finally, the effects of DACH1 on CXCL8, CXCL10, and CXCL12 expression in Nthy-ori-3-1, TPC-1 and Bcpap cells were assessed by enzyme-linked immunosorbent assay kit and real-time polymerase chain reaction, respectively. The results showed that DACH1 was differentially expressed in different tumors and tissues. Basal expression of DACH1 was lower in thyroid and papillary thyroid carcinoma than in other normal tissues and corresponding tumors, and positively correlated with CD8⁺ T cell infiltration. In Nthy-ori-3-1, TPC-1 and Bcpap cells, overexpression of DACH1 inhibited cell migration and proliferation, and the opposite results was obtained by knocking down DACH1 using small interfering RNA. We also demonstrated that DACH1 regulated chemokines CXCL8, CXCL10, and CXCL12, thereby modulating tumor immunity.

Co-Encapsulation of Paclitaxel and JQ1 in Zein Nanoparticles as Potential Innovative Nanomedicine

The manuscript describes the development of zein nanoparticles containing paclitaxel (PTX) and the bromo-and extra-terminal domain inhibitor (S)-tertbutyl2-(4-(4-chlorophenyl)-2,3,9-trimethyl-6H-thieno(3,2-f)(1,2,4)triazolo(4,3-a)(1,4)diazepin-6-yl)acetate (JQ1) together with their cytotoxicity on triple-negative breast cancer cells. The rationale of this association is that of exploiting different types of cancer cells as targets in order to obtain increased pharmacological activity with respect to that exerted by the single agents. Zein, a protein found in the endosperm of corn, was used as a biomaterial to obtain multidrug carriers characterized by mean sizes of ˂200 nm, a low polydispersity index (0.1-0.2) and a negative surface charge. An entrapment efficiency of ~35% of both the drugs was obtained when 0.3 mg/mL of the active compounds were used during the nanoprecipitation procedure. No adverse phenomena such as sedimentation, macro-aggregation or flocculation occurred when the nanosystems were heated to 37 °C. The multidrug nanoformulation demonstrated significant in vitro cytototoxic activity against MDA-MB-157 and MDA-MB-231 cancer cells by MTT-test and adhesion assay which was stronger than that of the compounds encapsulated as single agents. The results evidence the potential application of zein nanoparticles containing PTX and JQ1 as a novel nanomedicine.

Identification of Exosomal microRNAs and Their Targets in Papillary Thyroid Cancer Cells

The release of molecules in exosomal cargoes is involved in tumor development and progression. We compared the profiles of exosomal microRNAs released by two thyroid cancer cell lines (TPC-1 and K1) with that of non-tumorigenic thyroid cells (Nthy-ori-3-1), and we explored the network of miRNA–target interaction. After extraction and characterization of exosomes, expression levels of microRNAs were investigated using custom TaqMan Advanced array cards, and compared with those expressed in the total cell extracts. The functional enrichment and network-based analysis of the miRNAs’ targets was also performed. Five microRNAs (miR-21-5p, miR-31-5p, miR-221-3p, miR-222-3p, and let-7i-3p) were significantly deregulated in the exosomes of tumor cells vs. non-tumorigenic cells, and three of them (miR-31-5p, miR-222-3p, and let-7i-3p) in the more aggressive K1 compared to TPC-1 cells. The network analysis of the five miRNAs identified some genes as targets of more than one miRNAs. These findings permitted the identification of exosomal microRNAs secreted by aggressive PTC cells, and indicated that their main targets are regulators of the tumor microenvironment. A deeper analysis of the functional role of the targets of exosomal miRNAs will provide further information on novel targets of molecular treatments for these neoplasms.

Quercetin Protects Human Thyroid Cells against Cadmium Toxicity

Various natural compounds have been successfully tested for preventing or counteracting the toxic effects of exposure to heavy metals. In this study, we analyzed the effects of cadmium chloride (CdCl₂) on immortalized, non-tumorigenic thyroid cells Nthy-ori-3-1. We investigated the molecular mechanism underlying its toxic action as well as the potential protective effect of quercetin against CdCl₂-induced damage. CdCl₂ suppressed cell growth in a dose- and time-dependent manner (IC50 value ~10 μM) associated with a decrease in levels of phospho-ERK. In addition, CdCl₂ elicited an increase in reactive oxygen species (ROS) production and lipid peroxidation. A significant increase in GRP78, an endoplasmic reticulum (ER) stress-related protein, was also observed. Supplementation of quercetin counteracted the growth-inhibiting action of CdCl₂ by recovering ERK protein phosphorylation levels, attenuating ROS overproduction, decreasing MDA content and reducing the expression of GRP78 in cells exposed to CdCl₂. Thus, in addition to revealing the molecular effects involved in cadmium-induced toxicity, the present study demonstrated, for the first time, a protective effect of quercetin against cadmium-induced damages to normal thyroid cells.

Increased Thyroid Cancer Incidence in Volcanic Areas: A Role of Increased Heavy Metals in the Environment?

Thyroid cancer incidence is significantly increased in volcanic areas, where relevant non-anthropogenic pollution with heavy metals is present in the environment. This review will discuss whether chronic lifelong exposure to slightly increased levels of metals can contribute to the increase in thyroid cancer in the residents of a volcanic area. The influence of metals on living cells depends on the physicochemical properties of the metals and their interaction with the target cell metallostasis network, which includes transporters, intracellular binding proteins, and metal-responsive elements. Very little is known about the carcinogenic potential of slightly increased metal levels on the thyroid, which might be more sensitive to mutagenic damage because of its unique biology related to iodine, which is a very reactive and strongly oxidizing agent. Different mechanisms could explain the specific carcinogenic effect of borderline/high environmental levels of metals on the thyroid, including (a) hormesis, the nonlinear response to chemicals causing important biological effects at low concentrations; (b) metal accumulation in the thyroid relative to other tissues; and (c) the specific effects of a mixture of different metals. Recent evidence related to all of these mechanisms is now available, and the data are compatible with a cause–effect relationship between increased metal levels in the environment and an increase in thyroid cancer incidence.