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Carbon black and cadmium (Cd) are important components of atmospheric particulate matter and cigarette smoke that are closely associated with the occurrence and development of lung diseases. Carbon black, particularly carbon black nanoparticles (CBNPs), can easily adsorbs metals and cause severe lung damage and even cell death. Therefore, this study aimed to explore the mechanisms underlying the combined toxicity of CBNPs and Cd. We found that the combined exposure to CBNPs and Cd promoted significantly greater autophagosome formation and ferroptosis (increased malonaldehyde (MDA), reactive oxygen species (ROS), and divalent iron ions (Fe2+) levels and altered ferroptosis-related proteins) compared with single exposure in both 16HBE cells (human bronchial epithelioid cells) and mouse lung tissues. The levels of ferroptosis proteins, transferrin receptor protein 1 (TFRC) and glutathione peroxidase 4 (GPX4), were restored by CBNPs-Cd exposure following treatment with a 3-MA inhibitor. Additionally, under CBNPs-Cd exposure, circPSEN1 overexpression inhibited increases in the autophagy proteins microtubule-associated protein 1 light chain 3 (LC3II/I) and sequestosome-1 (P62). Moreover, increases in TFRC and Fe2+, and decreases in GPX4were inhibited. Knockdown of circPSEN1 reversed these effects. circPSEN1 interacts with autophagy-related gene 5 (ATG5) protein and upregulates nuclear receptor coactivator 4 (NCOA4), the co-interacting protein of ATG5, thereby degrading ferritin heavy chain 1 (FTH1) and increasing Fe2+ in 16HBE cells. These results indicated that the combined exposure to CBNPs and Cd promoted the binding of circPSEN1 to ATG5, thereby increasing autophagosome synthesis and ATG5-NCOA4-FTH1 axis activation, ultimately inducing autophagy-dependent ferroptosis in 16HBE cells and mouse lung tissues. This study provides novel insights into the toxic effects of CBNPs and Cd in mixed pollutants. [Display omitted] • Carbon black and cadmium co-exposure induce autophagy-dependent ferroptosis. • CircPSEN1 interacts with ATG5 protein to facilitate autophagosome formation. • CircPSEN1 activates ATG5-NCOA4-FTH1 axis leading to ferroptosis. • Ferroptosis induced by carbon black and cadmium co-exposure may be synergistic effect. [ABSTRACT FROM AUTHOR]

Background: Lung cancer has high morbidity and mortality worldwide with non-small cell lung cancer (NSCLC) accounting for 85% of the cases. Therapies for lung cancer have relatively poor outcomes and further improvements are required. Circular RNAs have been reported to participate in the occurrence and progression of cancer. Information on the functions and mechanism of circRNAs in lung cancer is limited and needs more exploration. Methods: We detected expression of genes and proteins by qPCR and western blot. Function of circSATB2 was investigated using RNA interference and overexpression assays. Location of circSATB2 was assessed by fluorescence in situ hybridization (FISH). Interaction of circSATB2, miR-326 and FSCN1 was confirmed by dual-luciferase reporter assay. Results: Data from the investigation showed that circSATB2 was highly expressed in NSCLC cells and tissues. circSATB2 positively regulated fascin homolog 1, actin-bundling protein 1 (FSCN1) expression via miR-326 in lung cancer cells. Furthermore, circSATB2 can be transferred by exosomes and promote the proliferation, migration and invasion of NSCLC cells, as well as induce abnormal proliferation in normal human bronchial epithelial cells. Also, circSATB2 was highly expressed in serumal exosomes from lung cancer patients with high sensitivity and specificity for clinical detection and was related to lung cancer metastasis. Conclusions: circSATB2 participated in the progression of NSCLC and was differentially expressed in lung cancer tissue and serumal exosomes. circSATB2 may be potential biomarker for the diagnosis of NSCLC. [ABSTRACT FROM AUTHOR]

Benzo [a]pyrene (B [a]P) is a widespread environmental chemical pollutant that has been linked to the development of various diseases. However, the specific mechanism of action remains unclear. In this study, human bronchial epithelial 16HBE and BEAS-2B cells were exposed to B [a]P at 0–32 μM to assess the DNA-damaging effects. B [a]P exposure resulted in elevated expression of γ-H2AX, a marker of DNA damage. The m6A RNA methylation assay showed that B [a]P exposure increased the extent of m6A modification and the demethylase ALKBH5 played an integral role in this process. Moreover, the results of the comet assay and Western blot analysis showed an increase in m6A modification mediated by ALKBH5 that promoted DNA damage. Furthermore, the participation of a novel circular RNA, circ_0003552, was assessed by high-throughput sequencing under the condition of high m6A modification induced by B [a]P exposure. In subsequent functional studies, an interference/overexpression system was created to confirm that circ_0003552 participated in regulation of DNA damage. Mechanistically, circ_0003552 had an m6A binding site that could regulate its generation. This study is the first to report that B [a]P upregulated circ_0003552 through m6A modification, thereby promoting DNA damage. These findings revealed that epigenetics played a key role in environmental carcinogen-induced DNA damage, and the quantitative changes it brought might provide an early biomarker for future medical studies of genetic-related diseases and a new platform for investigations of the interaction between epigenetics and genetics. [Display omitted] • B [a]P induces DNA damage in bronchial epithelial cells. • B [a]P upregulates the degree of m6A modification by suppressing ALKBH5 expression. • Both ALKBH5 and circ_0003552 can regulate the B [a]P-induced DNA damage. • M6A modification promotes circ_0003552 production through the m6A binding site. [ABSTRACT FROM AUTHOR]

• CircRNA interact with protein to regulate the PM 2.5 -induced inflammatory responses. • Circ_406961 inhibit PM 2.5 -induced BEAS-2B cells inflammatory responses. • ILF2 affect inflammatory response via STAT3/JNK signal pathway. Fine particulate matter (PM 2.5) has been verified to augmented the incidence of pneumonia, asthma, pulmonary fibrosis, and other pulmonary diseases. Airway inflammation is the pathological basis of the respiratory system, and understanding the molecular mechanisms responsible for airway inflammation may thus support the diagnosis and treatment of respiratory diseases. In our study, human bronchial epithelial cells (BEAS-2B) were exposed to various concentrations of PM 2.5 for 48 h. PM 2.5 entered the cells, resulting in increased production of interleukin 6 (IL-6) and interleukin 8 (IL-8) and decreased the expression of circular RNA 406961 (circ_406961). Further, PM 2.5 with a concentration of 75 μg/mL was applied to mechanism study. Functional experiments further confirmed that circ_406961 inhibited PM 2.5 -induced BEAS-2B cell inflammation. RNA pull-down and mass spectrometry showed that circ_406961 interacted with interleukin enhancer-binding factor 2 (ILF2), which could regulate phosphorylation of signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase 8 (MAPK8, JNK). Our studies showed that circ_406961 inhibited activation of STAT3/JNK pathways via interacting with ILF2 protein, thereby inhibiting the PM 2.5 -induced inflammatory reaction. [ABSTRACT FROM AUTHOR]

Long-term exposure to particulate matter 2.5 (PM 2.5) is closely related to the occurrence and development of airway inflammation. Exploration of the role of PM 2.5 in inflammation is the first step towards clarifying the harmful effects of particulate pollution. However, the molecular mechanisms underlying PM 2.5 -induced airway inflammation are yet to be fully established. In this study, we focused on the specific roles of non-coding RNAs (ncRNAs) in PM 2.5 -induced airway inflammation. In a human bronchial epithelial cell line, BEAS-2B, PM 2.5 at a concentration of 75 μg/mL induced the inflammatory response. Microarray and quantitative real-time polymerase chain reaction (qRT-PCR) analyses revealed significant upregulation of circRNA104250 and lncRNAuc001.dgp.1 during the PM 2.5 -induced inflammatory response in this cell line. Data from functional analyses further showed that both molecules promote an inflammatory response. CircRNA104250 and lncRNAuc001.dgp.1 target miR-3607-5p and affect expression of interleukin 1 receptor 1 (IL1R1), which influences the nuclear factor κB (NF-κB) signaling pathway. In summary, we have uncovered an underlying mechanism of airway inflammation by PM 2.5 involving regulation of ncRNA for the first time, which provides further insights into the toxicological effects of PM 2.5. Image 1 • CircRNA and lncRNA mediate the PM 2.5 -induced inflammatory response in BEAS-2B cells. • CircRNA and lncRNA augment PM 2.5 -induced IL-6 and IL-8 section. • CircRNA and lncRNA affect inflammatory response via NF-κB signal pathway. • CircRNA and lncRNA co-target miRNA in PM 2.5 -exposed BEAS-2B cells. Main findings of the work: CircRNA104250 and lncRNAuc001.dgp.1 promote the PM 2.5 -induced inflammatory response by co-targeting miR-3607-5p. [ABSTRACT FROM AUTHOR]

circNOL10 is a circular RNA expressed at low levels in lung cancer, though its functions in lung cancer remain unknown. Here, the function and molecular mechanism of circNOL10 in lung cancer development are investigated using in vitro and in vivo studies, and it is shown that circNOL10 significantly inhibits the development of lung cancer and that circNOL10 expression is co‐regulated by methylation of its parental gene Pre‐NOL10 and by splicing factor epithelial splicing regulatory protein 1 (ESRP1). circNOL10 promotes the expression of transcription factor sex comb on midleg‐like 1 (SCML1) by inhibiting transcription factor ubiquitination and thus also affects regulation of the humanin (HN) polypeptide family by SCML1. circNOL10 also affects mitochondrial function through regulating the humanin polypeptide family and affecting multiple signaling pathways, ultimately inhibiting cell proliferation and cell cycle progression, and promoting the apoptosis of lung cancer cells, thereby inhibiting lung cancer development. This study investigates the functions and molecular mechanisms of circNOL10 in the development of lung cancer and reveals its involvement in the transcriptional regulation of the HN polypeptide family by SCML1. The results also demonstrate the inhibitory effect of HN on lung cancer cells growth. These findings may identify novel targets for the molecular therapy of lung cancer. This study provides new evidence for the molecular mechanism whereby circRNAs may affect transcriptional regulation in lung cancer cells, and also reveals that circNOL10 inhibits lung cancer development by promoting SCLM1‐mediated transcriptional regulation of the humanin (HN) polypeptide family. The results also demonstrate the inhibitory effect of HN on lung cancer growth. [ABSTRACT FROM AUTHOR]

[Display omitted] Hexavalent chromium [Cr (VI)] is an important environmental pollutant and may cause lung injury when inhaled into the human body. Cr (VI) is genotoxic and can cause DNA damage, although the underlying epigenetic mechanisms remain unclear. To simulate the real-life workplace exposure to Cr (VI), we used a novel exposure dose calculation method. We evaluated the effect of Cr (VI) on DNA damage in human bronchial epithelial cells (16HBE and BEAS-2B) by calculating the equivalent real-time exposure dose of Cr (VI) (0 to 10 μM) in an environmental population. Comet experiments and olive tail moment measurements revealed increased DNA damage in cells exposed to Cr (VI). Cr (VI) treatment increased nuclear γ-H2AX foci and γ-H2AX protein expression, and caused DNA damage in the lung tissues of mice. An effective Cr (VI) dose (6 μM) was determined and used for cell treatment. Cr (VI) exposure upregulated circ_0008657, and knockdown of circ_0008657 decreased Cr (VI)-induced DNA damage, whereas circ_0008657 overexpression had the opposite effect. Mechanistically, we found that circ_0008657 binds to microRNA (miR)-203a-3p and subsequently regulates ATM serine/threonine kinase (ATM), a key protein involved in homologous recombination repair downstream of miR-203a-3p, thereby regulating DNA damage induced by Cr (VI). The present findings suggest that circ_0008657 competitively binds to miR-203a-3p to activate the ATM pathway and regulate the DNA damage response after environmental chemical exposure in vivo and in vitro. [ABSTRACT FROM AUTHOR]

• B[ a ]P induces DNA damage response (DDR) in bronchial epithelial cells. • B[ a ]P upregulates circ_0057504 through suppressing DNMT3A-mediated DNA methylation. • Circ_0057504 promotes B[ a ]P-induced DDR via modulating NONO-SFPQ complex formation. Benzo[ a ]pyrene (B[ a ]P) is a class I carcinogen and hazardous environmental pollutant with genetic toxicity. Understanding the molecular mechanisms underlying genetic deterioration and epigenetic alterations induced by environmental contaminants may contribute to the early detection and prevention of cancer. However, the role and regulatory mechanisms of circular RNAs (circRNAs) in the B[ a ]P-induced DNA damage response (DDR) have not been elucidated. In this study, human bronchial epithelial cell lines (16HBE and BEAS-2B) were exposed to various concentrations of B[ a ]P, and BALB/c mice were treated with B[ a ]P intranasally. B[ a ]P exposure was found to induce DNA damage and upregulate circular RNA hsa_circ_0057504 (circ_0057504) expression in vitro and in vivo. In addition, B[ a ]P upregulated TMEM194B mRNA and circ_0057504 expression through inhibition of DNA methyltransferase 3 alpha (DNMT3A) expression in vitro. Modulation (overexpression or knockdown) of circ_0057504 expression levels using a lentiviral system in human bronchial epithelial cells revealed that circ_0057504 promoted B[ a ]P-induced DNA damage. RNA pull-down and western blot assays showed that circ_0057504 interacted with non-POU domain-containing octamer-binding (NONO) and splicing factor proline and glutamine rich (SFPQ) proteins and regulated formation of the NONO-SFPQ protein complex. Thus, our findings indicate that circ_0057504 acts as a novel regulator of DNA damage in human bronchial epithelial cells exposed to B[ a ]P. The current study reveals novel insights into the role of circRNAs in the regulation of genetic damage, and describes the effect and regulatory mechanisms of circ_0057504 on B[ a ]P genotoxicity. [ABSTRACT FROM AUTHOR]

Exposure to high concentrations of copper is associated with pulmonary inflammation and chronic respiratory disease (CRD). Epigenetic modulation of noncoding RNAs contributes to the development of several CRDs. It is unknown whether epigenetic modulation is involved in copper mediated pulmonary inflammation and CRD. We conducted a case-control study of 101 CRD cases and 161 control subjects in Shijiazhuang, China, and evaluated circRNAs and cytokine levels (IL-6 and IL-8) by qPCR and ELISA. Urinary copper concentration was determined by inductively coupled plasma mass spectrometry. Linear mixed models and generalized linear mixed models were used to assess the associations of circRNAs with CRD, urinary copper, and cytokines. We exposed the human bronchial epithelial cell line, 16HBE, to copper and assessed the functional role of a circRNA, circ_0008882, by RNA overexpression. Cellular location of circ_0008882 was assessed by separation of nuclear and cytoplasmic RNAs. Nine circRNAs were associated with an increased risk for CRDs, while the relative expression of circ_0008882 was decreased after copper exposure in vitro and in vivo. Copper exposure stimulated 16HBE cells to release proinflammatory IL-6 and IL-8. The release of the cytokines was inhibited by overexpression of circ_0008882. These results suggest a role for circ_0008882 in the regulation of CRD associated inflammation following copper exposure. [Display omitted] • Circular RNA, circ_0008882, is related to chronic respiratory disease. • Expression of circ_0008882 decreases after copper exposure in vitro and in vivo. • IL-6 and IL-8, induced by copper, are inhibited by overexpression of circ_0008882. [ABSTRACT FROM AUTHOR]