Benzo[a]pyrene evokes epithelial-mesenchymal transition and pulmonary fibrosis through AhR-mediated Nrf2-p62 signaling

Dynamic characteristics of metabolism and small extracellular vesicles during malignant transformation of BEAS-2B cells induced by coal tar pitch extract

Lung cancer poses a significant global burden with rising morbidity and mortality. Coal tar pitch-induced lung cancer is an occupational disease where early detection is crucial but challenging due to unclear pathogenesis. We established a malignant transformation model using BEAS-2B cells treated with coal tar pitch extract (CTPE). Macro- and micro-observations showed CTPE-induced alterations, including changes in cell morphology, enhanced proliferation and migration abilities, upregulated EGFR expression, modified levels of CYP1A1 and GSTM1 metabolizing enzymes, and a transition towards a mesenchymal phenotype. These findings strongly suggest that the cells have undergone malignant transformation. Metabolomics analysis revealed changes in 1120 metabolites, with 31 co-expressed, mainly in energy and amino acid metabolism. Small extracellular vesicles (SEVs) concentrations and EGFR levels were significantly altered. Correlation analysis identified a relationship between these biomarkers, implying their potential significance as early events in the initiation and progression of lung cancer. These findings provide valuable insights and a rationale for lung cancer screening and mechanistic investigations, thereby contributing to a deeper understanding of the disease.

Pulmonary fibrosis: from mechanisms to therapies

Pulmonary fibrosis (PF) is a chronic, progressive interstitial lung disease characterized by excessive deposition of extracellular matrix (ECM) and abnormal fibroblast proliferation, which is mainly caused by air pollution, smoking, aging, occupational exposure, environmental pollutants exposure, and microbial infections. Although antifibrotic agents such as pirfenidone and nintedanib, approved by the United States (US) Food and Drug Administration (FDA), can slow the decline in lung function and disease progression, their side effects and delivery inefficiency limit the overall prognosis of PF. Therefore, there is an urgent need to develop effective therapeutic targets and delivery approaches for PF in clinical settings. This review provides an overview of the pathogenic mechanisms, therapeutic drug targeting signaling pathways, and promising drug delivery strategies for treating PF.

The influence and mechanisms of exogenous aryl hydrocarbon receptor ligands on the viability of mouse germ cells

Environmental pollution is a significant contributor to male infertility. Numerous environmental pollutants, such as PCB118, act as exogenous ligands for the aryl hydrocarbon receptor (AhR). However, the role of AhR in mediating the effects of environmental pollutants on male reproductive functions remains inadequately understood. In the present study, we assessed the viability of GC-1 and GC-2 cells using the CCK-8 assay. Immunofluorescence and Western blotting techniques were employed to investigate the distribution and protein expression levels of AhR within these cell lines. Alterations in reactive oxygen species (ROS) levels and mitochondrial membrane potential (MMP) were evaluated using DCFH-DA dye and the JC-1 assay, respectively. Furthermore, we investigated changes in the expression levels of Nrf2, Cleaved-Caspase 3, Cleaved-Caspase 8, Bcl-2, and Bax through Western blot analysis. Our findings indicate that PCB118 and the AhR-specific agonist CAY10465 diminish the viability of GC-1 and GC-2 cells, facilitate the nuclear translocation and expression of AhR protein, elevate ROS levels, and reduce MMP. Moreover, these agents markedly increase the levels of Cleaved-Caspase 3 and Cleaved-Caspase 8 while decreasing the Bax/Bcl-2 ratio. Notably, the AhR antagonist CH223191 and resveratrol have the capacity to restore the functionality of GC-1 and GC-2 cells by mitigating the effects of PCB118 and CAY10465. Based on these observations, we propose that exogenous AhR ligands PCB118 and CAY10465 promote the nuclear translocation and upregulation of AhR expression in GC-1 and GC-2 cells. This process subsequently induces mitochondrial oxidative stress, wich activates the apoptotic signaling pathway and ultimately compromises cellular viability.

Alveolar epithelial cell dysfunction and epithelial-mesenchymal transition in pulmonary fibrosis pathogenesis

Pulmonary fibrosis (PF) is a progressive and lethal interstitial lung disease characterized by aberrant scar formation and destruction of alveolar architecture. Dysfunctional alveolar epithelial cells (AECs) play a central role in initiating PF, where chronic injury triggers apoptosis and disrupts epithelial homeostasis, leading to epithelial-mesenchymal transition (EMT). This dynamic reprogramming process causes AECs to shed epithelial markers and adopt a mesenchymal phenotype, fueling fibroblast activation and pathological extracellular matrix (ECM) deposition. This review systematically explores the multi-layered mechanisms driving AECs dysfunction and EMT, focusing on core signaling axes such as transforming growth factor-β (TGF-β)/Smad, WNT/β-catenin, NF-κB-BRD4, and nuclear factor erythroid 2-related factor 2 (Nrf2), which regulate EMT and fibroblast-ECM interactions. It also highlights emerging regulators, including metabolic reprogramming, exosomal miRNA trafficking, and immune-epithelial interactions. Furthermore, understanding these mechanisms is essential for developing targeted therapeutic strategies to modulate these pathways and halt or reverse fibrosis progression, offering critical insights into potential clinical treatments for PF.

Gui-zhi-fu-ling-wan alleviates bleomycin-induced pulmonary fibrosis through inhibiting epithelial-mesenchymal transition and ferroptosis

Background

Idiopathic pulmonary fibrosis (IPF) has a higher morbidity and poor prognosis. Gui-Zhi-Fu-Ling-Wan (GFW) is a traditional Chinese herbal formula which exerts anti-inflammatory and anti-oxidative effects. The goal was to determine the protective effect of GFW on bleomycin (BLM)-induced pulmonary fibrosis.

Methods

One hundred and twenty-four mice were randomly divided into eight groups, and orally supplemented with GFW (1 g/kg) in 1 week ago and continuing to 1 week later of single BLM intratracheal injection (5.0 mg/kg). Lung tissues were collected in 7 days and 21 days after BLM injection. BEAS-2B cells were pretreated with GFW (100 μg/mL) for three consecutive days before BLM (10 μg/mL) exposure. Cells were harvested in 12 or 24 h after BLM co-culture.

Results

GFW supplementation alleviated BLM-induced alveolar structure destruction and inflammatory cell infiltration in mice lungs. BLM-incurred collagen deposition was attenuated by GFW. In addition, GFW pretreatment repressed BLM-evoked downregulation of E-cadherin, and elevation of N-cadherin and Vimentin in mouse lungs. Besides, BLM-excited GPX4 reduction, ferritin increases, lipid peroxidation, and free iron overload were significantly relieved by GFW pretreatment in mouse lungs and BEAS-2B cells. Notably, BLM-provoked mitochondrial reactive oxygen species (mtROS) excessive production, elevation of mitochondrial stress markers, such as HSP70 and CLPP, and mitochondrial injury, were all abolished in mouse lungs and BEAS-2B cells by GFW pretreatment.

Conclusion

GFW supplementation attenuated BLM-evoked lung injury and pulmonary fibrosis partially through repressing EMT and mtROS-mediated ferroptosis in pulmonary epithelial cells.

Benzo[a]pyrene exposure and incident risks of digestive system cancers: Insights from nested case-control studies and adverse outcome pathway network analysis

Benzo[a]pyrene (B[a]P) is a recognized carcinogen for lung cancer, but its associations with digestive system cancers (DSCs) remain unclear and the common carcinogenic mechanisms are not fully understood. We conducted five nested case-control studies within the Dongfeng-Tongji cohort, including esophageal (EC, n = 58), gastric (GC, n = 103), colorectal (CRC, n = 220), hepatic (HC, n = 117), and pancreatic cancers (PC, n = 45). For each case, two sex and age ( ± 5 years) matched healthy controls were selected. We observed significant J-shaped associations between plasma concentrations of benzo[a]pyrene diol epoxide-albumin (BPDE-Alb) adducts and five DSCs (all P for non-linear <0.05). The subjects with high BPDE-Alb exposure exhibited a separate 2.19, 2.14, 1.67, 2.40, and 1.78-fold incident risks of EC, GC, CRC, HC, and PC (95% CI: 1.00-4.83, 1.24-3.67, 1.15-2.43, 1.48-3.90, and 0.71-4.47, respectively) than those with low exposure. Furthermore, the adverse outcome pathway (AOP) network indicated five molecular initiation events and 18 subsequent key events, particularly, the alterations in receptors of AhR, EGFR accompanied by regulations of cell proliferation and apoptosis pathways (e.g., PI3K-Akt, TNF signaling) may facilitate common carcinogenic processes. Our findings revealed the positive associations of B[a]P exposure with five DSCs, and the dysregulation of proliferation and apoptosis may initiate B[a]P-induced cancer development.

Aryl hydrocarbon receptor (AHR) and nuclear factor erythroid-derived 2-like 2 (NRF2): An important crosstalk in the gut-liver axis

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor, mainly involved in detoxification. However, in the intestine, metabolites derived from the diet, which are converted by a wide range of bacteria can also activate the AHR. This intestinal AHR activation plays a key role in maintaining the gut barrier by, for example, upregulating antimicrobial peptides and anti-inflammatory cytokines. Since the gut barrier influences the gut-liver axis by regulating the leaking of metabolites, bacteria, and endotoxins into circulation and particularly into the liver, the AHR is a key factor in the gut-liver axis. Vice versa, certain liver pathologies also influence the gut microbiome, thereby altering bacteria-derived activation of the AHR. Additionally, bile acids can impact the gut via the liver and thereby also affect the AHR. The aryl hydrocarbon receptor (AHR) interacts with several molecular factors, one of which is the nuclear factor erythroid-derived 2-like 2 (NRF2), a transcription factor primarily associated with regulating antioxidant stress responses. The interplay between AHR and NRF2 has been investigated in the context of various diseases; this review highlights the significance of this interaction within the framework of the gut-liver axis.

Pyruvate kinase M2 modulates mitochondrial dynamics and EMT in alveolar epithelial cells during sepsis-associated pulmonary fibrosis

BACKGROUND

Pulmonary fibrosis (PF) severely impacts both the survival and quality of life of patients with acute respiratory distress syndrome (ARDS) and remains a leading cause of late-stage ARDS-related mortality. The role of epithelial-mesenchymal transition (EMT) in alveolar epithelial cells (AECs) is pivotal in the development of PF.

METHODS

This study explored the modulation of mitochondrial dynamics and the induction of EMT by pyruvate kinase M2 (PKM2) in AECs, aiming to identify new strategies for the prevention and treatment of sepsis-associated PF.

RESULTS

The results demonstrated that exposure to LPS increased the levels of PKM2 and the mitochondrial fission marker dynamin-related protein-1 (DRP1), while reducing the levels of the mitochondrial fusion marker mitofusin-2 (MFN2) and the epithelial marker E-cadherin. Moreover, the mesenchymal markers α-SMA and vimentin were upregulated. Treatment with shikonin effectively reversed these alterations, restoring the balance of mitochondrial dynamics, reversing EMT markers, and alleviating the severity of sepsis-associated PF.

CONCLUSIONS

This study identified PKM2 as a crucial regulator of mitochondrial dynamics and EMT in AECs during sepsis-associated PF. Targeting PKM2 activity offers a promising strategy for developing treatments to mitigate the progression of sepsis-associated PF.

Identification of benzo(a)pyrene-related toxicological targets and their role in chronic obstructive pulmonary disease pathogenesis: a comprehensive bioinformatics and machine learning approach

BACKGROUND

Chronic obstructive pulmonary disease (COPD) pathogenesis is influenced by environmental factors, including Benzo(a)pyrene (BaP) exposure. This study aims to identify BaP-related toxicological targets and elucidate their roles in COPD development.

METHODS

A comprehensive bioinformatics approach was employed, including the retrieval of BaP-related targets from the Comparative Toxicogenomics Database (CTD) and Super-PRED database, identification of differentially expressed genes (DEGs) from the GSE76925 dataset, and protein-protein interaction (PPI) network analysis. Functional enrichment and immune infiltration analyses were conducted using GO, KEGG, and ssGSEA algorithms. Feature genes related to BaP exposure were identified using SVM-RFE, Lasso, and RF machine learning methods. A nomogram was constructed and validated for COPD risk prediction. Molecular docking was performed to evaluate the binding affinity of BaP with proteins encoded by the feature genes.

RESULTS

We identified 72 differentially expressed BaP-related toxicological targets in COPD. Functional enrichment analysis highlighted pathways related to oxidative stress and inflammation. Immune infiltration analysis revealed significant increases in B cells, DC, iDC, macrophages, T cells, T helper cells, Tcm, and TFH in COPD patients compared to controls. Correlation analysis showed strong links between oxidative stress, inflammation pathway scores, and the infiltration of immune cells, including aDC, macrophages, T cells, Th1 cells, and Th2 cells. Seven feature genes (ACE, APOE, CDK1, CTNNB1, GATA6, IRF1, SLC1A3) were identified across machine learning methods. A nomogram based on these genes showed high diagnostic accuracy and clinical utility. Molecular docking revealed the highest binding affinity of BaP with CDK1, suggestive of its pivotal role in BaP-induced COPD pathogenesis.

CONCLUSIONS

The study elucidates the molecular mechanisms of BaP-induced COPD, specifically highlighting the role of oxidative stress and inflammation pathways in promoting immune cell infiltration. The identified feature genes may serve as potential biomarkers and therapeutic targets. Additionally, the constructed nomogram demonstrates high accuracy in predicting COPD risk, providing a valuable tool for clinical application in BaP-exposed individuals.

State-of-the-Art Nrf2 Inhibitors: Therapeutic Opportunities in Non-Cancer Diseases

Nuclear factor erythroid 2-related factor (Nrf2) is a cytoprotective transcription factor that induces the transcription of genes responsible for the cell's response to oxidative stress. While Nrf2 activation has led to the development of clinically relevant therapeutics, the oncogenic role of Nrf2 in the proliferation of cancer cells has underscored the complex nature of Nrf2 and the necessity for the development of Nrf2 inhibitors. Although the application of Nrf2 inhibitors appears limited as anticancer agents, recent studies have begun to pinpoint the impairment of autophagy in diseases as a cellular marker that shifts Nrf2 from a protective to a deleterious state. Therefore, the cytoplasmic accumulation of Nrf2 can lead to the accumulation of lipid hydroperoxides and, ultimately, to ferroptosis. However, some studies aimed at elucidating the role of Nrf2 in non-cancer diseases have yielded conflicting results, attributed to differences in approaches used to inhibit or activate Nrf2, as well as variations in in vitro and/or in vivo disease models. Overall, these results highlight the necessity for a deeper evaluation of Nrf2's role in diseases, especially chronic diseases. In this review, we discuss diseases where Nrf2 inhibition holds potential for beneficial therapeutic effects and summarize recently reported Nrf2 inhibitors exploiting medicinal chemistry approaches suitable for targeting transcription factors like Nrf2.