Understanding the mechanistic roles of environmental heavy metal stressors in regulating ferroptosis: adding new paradigms to the links with diseases

Prognostic predictive modeling of non-small cell lung cancer associated with cadmium-related pathogenic genes

Persistent exposure to low-dose of cadmium is strongly linked to both the development and prognosis of non-small cell lung cancer (NSCLC), yet the precise molecular mechanism behind this relationship remains uncertain. In this study, cadmium-related pathogenic genes (CRPGs) in NSCLC were identified via differential expression analysis. NSCLC patient clusters related to CRPGs were constructed through univariate Cox and K-means clustering algorithms. Multivariate Cox and least absolute shrinkage and selection operator (LASSO) regression analyses were employed to determine the prognosis. Sixteen CRPGs showed a significant association with NSCLC. We found biological and prognostic differences between patients in clusters A and B. A predictive prognostic risk model for NSCLC revealed that FAM83H, MSMO1, and SNAI1 are central. Hence, the 3 hub genes were named. To further elucidate the role of CRPGs in NSCLC, A549 cells were exposed to CdCl2. The mRNA and protein expression levels of the 3 hub genes and cell invasion were detected. Moreover, 10 μM CdCl2 may increase the protein expression of 3 hub genes and enhance the invasive ability of A549 cells. This risk model may have established a theoretical foundation for investigating the mechanisms, treatment, and prognosis of NSCLC.

Gemcitabine-loaded chitosan nanoparticles enhanced apoptotic and ferroptotic response of gemcitabine treatment alone in the pancreatic cancer cells in vitro

Gemcitabine (GEM) is a first-line treatment for pancreatic ductal adenocarcinoma (PDAC) patients, causing side effects and poor overall survival. Eighty percent of patients often develop resistance rapidly to GEM. Developing therapeutic approaches and increasing sensitivity to gemcitabine in PDAC has become one of the challenges in cancer research. We synthesized GEM-loaded NPs prepared with a method that combines ultrasonication and ionotropic gelation to overcome GEM-related limitations in PDAC. CFPAC-1 cells were treated with increased concentrations of GEM, empty chitosan, and GEM-loaded NPs (0.66, 1.32, 2.64, 5.32 µg/ml) for up to 48 h. Empty chitosan NPs did not show toxicity on L929 cells. Antioxidant enzyme activities, including glucose 6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6-PGD), glutathione reductase (GR), glutathione s-transferase (GST), and glutathione peroxidase (GPx), significantly reduced in GEM-loaded NPs compared to the GEM associated with increased oxidative stress, PPP, and glycolysis. Bcl-xL, NOXA/mcl-1, and Ca2+ levels significantly increased in GEM-loaded NP-administered cells compared to the GEM and control groups. In contrast, JNK, p38, STAT3, Akt, and CREB levels significantly decreased in the GEM-loaded NP group, addressing enhanced apoptotic response compared to the GEM alone. Increased ferroptosis activity in GEM-loaded NP-administered groups has been validated via decreased antioxidant enzyme activities, increased cytosolic Fe, Zn, Mg, and Mn levels, and reduced GPx activity compared to the GEM and control groups. For the first time in the literature, we showed biocompatible GEM-loaded NPs enhanced apoptotic and ferroptotic response in CFPAC-1 cells via downregulation of antioxidant, glycolysis, and PPP metabolism compared to the GEM alone.

NCOA4-mediated ferritinophagy participates in cadmium-triggered ferroptosis in spermatogonia

Cadmium (Cd) is a common pollutant with reproductive toxicity. Our previous study revealed that Cd triggered spermatogonia ferroptosis. However, the underlying mechanisms remain unclear. Nuclear receptor coactivator 4 (NCOA4) mediates ferritinophagy and specific degradation of ferritin through lysosomes, resulting in the release of ferrous ions. Excessive autophagy can lead to ferroptosis. This study investigated the role of autophagy in Cd-triggered ferroptosis using GC-1 spermatogonial (spg) cells which exposed to CdCl2 (5 μM, 10 μM, or 20 μM) for 24 without/with CQ. The cells which transfected with Ncoa4-siRNA were used to explore the role of NCOA4-mediated ferritinophagy in Cd-triggered ferroptosis. The results revealed that Cd caused mitochondrial swelling, rupture of cristae, and vacuolar-like changes. The Cd-treated cells exhibited more autophagosomes. Simultaneously, Cd increased intracellular iron, reactive oxygen species, and malondialdehyde concentrations while decreasing glutathione content and Superoxide Dismutase-2 activity. Moreover, Cd upregulated mRNA levels of ferritinophagy-associated genes (Ncoa4, Lc3b and Fth1), as well as enhanced protein expression of NCOA4, LC3B, and FTH1. While Cd decreased the mRNA and protein expression of p62/SQSTM1. These results showed that Cd caused ferritinophagy and ferroptosis. The use of chloroquine to inhibit autophagy ameliorated Cd-induced iron overload and ferroptosis. Moreover, Ncoa4 knockdown in spermatogonia significantly reduced intracellular iron concentration and alleviated Cd-triggered ferroptosis. In conclusion, our findings demonstrate that Cd activates the ferritinophagy pathway mediated by NCOA4, resulting in iron accumulation through ferritin degradation. This causes oxidative stress, ultimately initiating ferroptosis in spermatogonia. Our results may provide new perspectives and potential strategies for preventing and treating Cd-induced reproductive toxicity.

Urea cycle promotion via ammonia-upregulated CPS1 is involved in arsenite-induced pulmonary fibrosis through enhancing collagen synthesis

Arsenic exposure is connected with lung toxicity and is related to lung fibrotic changes. Idiopathic pulmonary fibrosis (IPF) is characterized by extracellular matrix (ECM) deposition. Various genetic mechanisms and environmental factors induce or exacerbate pulmonary fibrosis. Collagen synthesis induced by sodium arsenite (NaAsO2) is closely associated with IPF. Fibroblasts tend to fine-tune their metabolic networks to support their synthetic requirements in response to environmental stimuli. Alterations in metabolism have an influential role in the pathogenesis of IPF. However, it is unclear how arsenic affects the metabolism in IPF. The urea cycle (UC) is needed for collagen formation, which provides adequate levels of proline (Pro) for biosynthesis of collagen. Carbamoyl phosphate synthetase 1 (CPS1) converts the ammonia to carbamoyl phosphate, which controls the first reaction of the UC. We show that, in arsenite-exposed mice, high amounts of ammonia in the lung microenvironment promotes the expression levels of CPS1 and the Pro metabolism. Reduction of ammonia and CPS1 ablation inhibit collagen synthesis and ameliorate IPF phenotypes induced by arsenite. This work takes advantage of multi-omics data to enhance understanding of the underlying pathogenic mechanisms, the key molecules and the complicated cellular responses to this pollutant, which provide a target for the prevention of pulmonary fibrosis caused by arsenic.

Protective effects and mechanism of chemical- and plant-based selenocystine against cadmium-induced liver damage

Although selenium (Se) and cadmium (Cd) often coexist naturally in the soil of China, the health risks to local residents consuming Se-Cd co-enriched foods are unknown. In the present study, we investigated the effects of chemical-based selenocystine (SeCys2) on cadmium chloride-induced human hepatocarcinoma (HepG2) cell injury and plant (Cardamine hupingshanensis)-derived SeCys2 against Cd-induced liver injury in mice. We found that chemical- and plant-based SeCys2 showed protective effects against Cd-induced HepG2 cell injury and liver damage in mice, respectively. Compared with Cd intervention group, co-treatment with chemical- or plant-based SeCys2 both alleviated liver toxicity and ferroptosis by decreasing ferrous iron, acyl-CoA synthetase long-chain (ACSL) family member 4, lysophosphatidylcholine acyltransferase 3, reactive oxygen species and lipid peroxide levels, and increasing ACSL3, peroxisome proliferator-activated receptor α, solute carrier family 7 member 11 (SLC7A11) and glutathione and glutathione peroxidase 4 (GPX4) levels. In conclusion, chemical- and plant-based SeCys2 alleviated Cd-induced hepatotoxicity and ferroptosis by regulating SLC7A11/GPX4 signaling and lipid peroxidation. Our findings indicate that potential Cd toxicity from consuming foods grown in Se- and Cd-rich soils should be re-evaluated. This study offers a new perspective for the development of SeCys2-enriched agricultural products.

Metal-induced autoimmunity in neurological disorders: A review of current understanding and future directions

Autoimmunity is a multifaceted disorder influenced by both genetic and environmental factors, and metal exposure has been implicated as a potential catalyst, especially in autoimmune diseases affecting the central nervous system. Notably, metals like mercury, lead, and aluminum exhibit well-established neurotoxic effects, yet the precise mechanisms by which they elicit autoimmune responses in susceptible individuals remain unclear. Recent studies propose that metal-induced autoimmunity may arise from direct toxic effects on immune cells and tissues, coupled with indirect impacts on the gut microbiome and the blood-brain barrier. These effects can activate self-reactive T cells, prompting the production of autoantibodies, inflammatory responses, and tissue damage. Diagnosing metal-induced autoimmunity proves challenging due to nonspecific symptoms and a lack of reliable biomarkers. Treatment typically involves chelation therapy to eliminate excess metals and immunomodulatory agents to suppress autoimmune responses. Prevention strategies include lifestyle adjustments to reduce metal exposure and avoiding occupational and environmental risks. Prognosis is generally favorable with proper treatment; however, untreated cases may lead to autoimmune disorder progression and irreversible organ damage, particularly in the brain. Future research aims to identify genetic and environmental risk factors, enhance diagnostic precision, and explore novel treatment approaches for improved prevention and management of this intricate and debilitating disease.

Quercetin Alleviates Perimenopausal Depression Induced by Ovariectomy Combined with Chronic Unpredictable Mild Stress Through Regulating Serum Elements and Inhibiting Ferroptosis in Prefrontal Cortex of Rats

This study investigated the effects of quercetin on the alterations of serum elements in perimenopausal depression rat model induced by ovariectomy combined with chronic unpredictable mild stress (OVX-CUMS) and possible mechanisms. According to the results of the sucrose preference test, the rats were randomly assigned to four groups: sham, OVX-CUMS, OVX-CUMS + 17β-estradiol (17β-estradiol: 0.27 mg/kg.bw), and OVX-CUMS + Quercetin (Quercetin: 50 mg/kg.bw). At the end of experiment, serum and prefrontal cortex of rats were collected. The inductively coupled plasma mass spectrometry (ICP-MS) analysis showed that levels of calcium (Ca), magnesium (Mg), selenium (Se), cobalt (Co) and zinc (Zn) decreased, and levels of iron (Fe) and copper (Cu) increased in serum and prefrontal cortex of OVX-CUMS rats compared with sham group (p < 0.01). Meanwhile, the levels of the above elements in prefrontal cortex had correlation with behavioral characteristics in OVX-CUMS rats (p < 0.05 or p < 0.01). The abnormal elements in serum may cross blood-brain-barrier into the brain and induce oxidative stress, leading to ferroptosis. Furtherly, the expressions of ferroptosis-related protein including GPX4 and SLC7A11 were decreased in prefrontal cortex of OVX-CUMS rats (p < 0.01), which confirmed the above results. Quercetin treatment restored the above abnormal indicators (p < 0.05 or p < 0.01) induced by OVX-CUMS in rats. Our study suggested that quercetin regulated variation of elements in serum and prefrontal cortex, further inhibiting ferroptosis in prefrontal cortex through alleviating oxidative stress in OVX-CUMS rats.

A nationwide investigation on the characteristics and health risk of trace elements in surface water across China

Rapid urbanization accelerates the release of anthropogenic heavy metals from local to wider water systems, posing a serious threat to aquatic ecosystems and public health. The characteristics of trace elements were investigated to evaluate the environmental status of surface water in 40 cities of China. The concentrations of 22 elements in surface water ranged from 7.00 × 10-4 to 4.37 × 105 μg/L. The water quality can be classified as "excellent" except Songhuajiang. The levels of As, Cd, Cr, Pb, and Hg are all within the limits permitted by national drinking water quality standards. An obvious regional distribution characteristic was observed, with concentrations of Zn, Mn, Ni, Cu, Co, U, and Cr higher in surface water collected in the north than in the south, while the trends for Cd, Tl, and As are opposite. Notably, Tl shows significant geographical divergences, with the level of surface water collected from the south nine times higher than that from the north. The regional distribution of the mineral, industrial, or agricultural activity might be responsible for the south-to-north difference of these elements. The hazard index (HI) and total cancer risk (TCR) through oral or dermal contact with water-related heavy metals were further calculated. The average HI was 0.54 in the north and 0.29 in the south for adults, while HI for children was relatively higher. The value was 1.01 and 0.55 in the north and south, respectively. TCR in the north is 2.58 × 10-4 and mainly contributed by Cr (88.1 %), while TCR in the south is 4.48 × 10-5 and mainly contributed by As (98.4 %). The research results can provide essential data for effective water resources management and human health protection in China.

Understanding the mechanistic roles of microplastics combined with heavy metals in regulating ferroptosis: Adding new paradigms regarding the links with diseases

As a new type of pollutant, microplastics (MPs) commonly exist in today's ecosystems, causing damage to the ecological environment and the health of biological organisms, including human beings. MPs can function as carriers of heavy metals (HMs) to aggravate the enrichment of HMs in important organs of organisms, posing a great threat to health. Ferroptosis, a novel process for the regulation of nonapoptotic cell death, has been shown to be closely related to the occurrence and processes of MPs and HMs in diseases. In recent years, some HMs, such as cadmium (Cd), iron (Fe), arsenic (As) and copper (Cu), have been proven to induce ferroptosis. MPs can function as carriers of HMs to aggravate damage to the body. This damage involves oxidative stress, mitochondrial dysfunction, lipid peroxidation (LPO), inflammation, endoplasmic reticulum stress (ERS) and so on. Therefore, ferroptosis has great potential as a therapeutic target for diseases induced by MPs combined with HMs. This paper systematically reviews the potential effects and regulatory mechanisms of MPs and HMs in the process of ferroptosis, focusing on the mitochondrial damage, Fe accumulation, LPO, ERS and inflammation caused by MPs and HMs that affect the regulatory mechanism of ferroptosis, providing new insights for research on regulating drugs and for the development of ferroptosis-targeting therapy for Alzheimer's disease, Parkinson's disease, cancer and cardiovascular disease.

Role of intrinsic apoptosis in environmental exposure health outcomes

Environmental exposures are linked to diseases of high public health concern, including cancer, neurodegenerative disorders, and autoimmunity. These diseases are caused by excessive or insufficient cell death, prompting investigation of mechanistic links between environmental toxicants and dysregulation of cell death pathways, including apoptosis. This review describes how legacy and emerging environmental exposures target the intrinsic apoptosis pathway to potentially drive pathogenesis. Recent discoveries reveal that dynamic regulation of apoptosis may heighten the vulnerability of healthy tissues to exposures in children, and that apoptotic signaling can guide immune responses, tissue repair, and tumorigenesis. Understanding how environmental toxicants dysregulate apoptosis will uncover opportunities to deploy apoptosis-modulating agents for the treatment or prevention of exposure-linked diseases.

Drug Repurposing-Based Brain-Targeting Self-Assembly Nanoplatform Using Enhanced Ferroptosis against Glioblastoma

Glioblastoma (GBM), the most aggressive and lethal form of malignant brain tumor, is a therapeutic challenge due to the drug filtration capabilities of the blood-brain barrier (BBB). Interestingly, glioblastoma tends to resist apoptosis during chemotherapy, but is susceptible to ferroptosis. Developing therapies that can effectively target glioblastoma by crossing the BBB and evoke ferroptosis are, therefore, crucial for improving treatment outcomes. Herein, a versatile biomimetic nanoplatform, L-D-I/NPs, is designed that self-assembled by loading the antimalarial drug dihydroartemisinin (DHA) and the photosensitizer indocyanine green (ICG) onto lactoferrin (LF). This nanoplatform can selectively target glioblastoma by binding to low-density lipoprotein receptor-related protein-1 (LRP1) and crossing the BBB, thus inducing glioblastoma cell ferroptosis by boosting intracellular reactive oxygen species (ROS) accumulation and iron overload. In addition, L-D-I/NPs have demonstrated the ability to effectively suppress the progression of orthotopic glioblastoma and significantly prolong survival in a mouse glioblastoma model. This nanoplatform has facilitated the application of non-chemotherapeutic drugs in tumor treatment with minimal adverse effects, paving the way for highly efficient ferroptosis-based therapies for glioblastoma.

Multifunctional Metallothioneins as a Target for Neuroprotection in Parkinson's Disease

Parkinson's disease (PD) is characterized by motor symptoms based on a loss of nigrostriatal dopaminergic neurons and by non-motor symptoms which precede motor symptoms. Neurodegeneration accompanied by an accumulation of α-synuclein is thought to propagate from the enteric nervous system to the central nervous system. The pathogenesis in sporadic PD remains unknown. However, many reports indicate various etiological factors, such as oxidative stress, inflammation, α-synuclein toxicity and mitochondrial impairment, drive neurodegeneration. Exposure to heavy metals contributes to these etiopathogenesis and increases the risk of developing PD. Metallothioneins (MTs) are cysteine-rich metal-binding proteins; MTs chelate metals and inhibit metal-induced oxidative stress, inflammation and mitochondrial dysfunction. In addition, MTs possess antioxidative properties by scavenging free radicals and exert anti-inflammatory effects by suppression of microglial activation. Furthermore, MTs recently received attention as a potential target for attenuating metal-induced α-synuclein aggregation. In this article, we summarize MTs expression in the central and enteric nervous system, and review protective functions of MTs against etiopathogenesis in PD. We also discuss neuroprotective strategies for the prevention of central dopaminergic and enteric neurodegeneration by targeting MTs. This review highlights multifunctional MTs as a target for the development of disease-modifying drugs for PD.