Linking the generation of DNA adducts to lung cancer

Attenuation of Polycyclic Aromatic Hydrocarbon (PAH)-Induced Carcinogenesis and Tumorigenesis by Omega-3 Fatty Acids in Mice In Vivo

Lung cancer is the leading cause of cancer death worldwide. Polycyclic aromatic hydrocarbons (PAHs) are metabolized by the cytochrome P450 (CYP)1A and 1B1 to DNA-reactive metabolites, which could lead to mutations in critical genes, eventually resulting in cancer. Omega-3 fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are beneficial against cancers. In this investigation, we elucidated the mechanisms by which omega-3 fatty acids EPA and DHA will attenuate PAH-DNA adducts and lung carcinogenesis and tumorigenesis mediated by the PAHs BP and MC. Adult wild-type (WT) (A/J) mice, Cyp1a1-null, Cyp1a2-null, or Cyp1b1-null mice were exposed to PAHs benzo[a]pyrene (BP) or 3-methylcholanthrene (MC), and the effects of omega-3 fatty acid on PAH-mediated lung carcinogenesis and tumorigenesis were studied. The major findings were as follows: (i) omega-3 fatty acids significantly decreased PAH-DNA adducts in the lungs of each of the genotypes studied; (ii) decreases in PAH-DNA adduct levels by EPA/DHA was in part due to inhibition of CYP1B1; (iii) inhibition of soluble epoxide hydrolase (sEH) enhanced the EPA/DHA-mediated prevention of pulmonary carcinogenesis; and (iv) EPA/DHA attenuated PAH-mediated carcinogenesis in part by epigenetic mechanisms. Taken together, our results suggest that omega-3 fatty acids have the potential to be developed as cancer chemo-preventive agents in people.

Traffic-Related Air Pollution and Ground-Level Ozone Associated Global DNA Hypomethylation and Bulky DNA Adduct Formation

Studies have indicated that air pollution, including surface-level ozone (O₃), can significantly influence the risk of chronic diseases. To better understand the carcinogenic mechanisms of air pollutants and identify predictive disease biomarkers, we examined the association between traffic-related pollutants with DNA methylation alterations and bulky DNA adducts, two biomarkers of carcinogen exposure and cancer risk, in the peripheral blood of 140 volunteers-95 traffic police officers, and 45 unexposed subjects. The DNA methylation and adduct measurements were performed by bisulfite-PCR and pyrosequencing and ³²P-postlabeling assay. Airborne levels of benzo(a)pyrene [B(a)P], carbon monoxide, and tropospheric O₃ were determined by personal exposure biomonitoring or by fixed monitoring stations. Overall, air pollution exposure was associated with a significant reduction (1.41 units) in global DNA methylation (95% C.I. -2.65-0.04, p = 0.026). The decrement in ALU repetitive elements was greatest in the policemen working downtown (95% C.I. -3.23--0.49, p = 0.008). The DNA adducts were found to be significantly increased (0.45 units) in the municipal officers with respect to unexposed subjects (95% C.I. 0.02-0.88, p = 0.039), mainly in those who were controlling traffic in downtown areas (95% C.I. 0.39-1.29, p < 0.001). Regression models indicated an increment of ALU methylation at higher B(a)P concentrations (95% C.I. 0.03-0.60, p = 0.032). Moreover, statistical models showed a decrement in ALU methylation and an increment of DNA damage only above the cut-off value of 30 µg/m³ O₃. A significant increment of 0.73 units of IL-6 gene methylation was also found in smokers with respect to non-smokers. Our results highlighted the role of air pollution on epigenetic alterations and genotoxic effects, especially above the target value of 30 µg/m³ surface-level O₃, supporting the necessity for developing public health strategies aimed to reduce traffic-related air pollution molecular alterations.

Aqueous Extract of Artemisia annua Shows In Vitro Antimicrobial Activity and an In Vivo Chemopreventive Effect in a Small-Cell Lung Cancer Model

Artemisia annua (A. annua) has been used as a medicinal plant in the treatment of several infectious and non-infectious diseases in the forms of tea and press juice since ancient times. The aim of this study was to evaluate the aqueous extract of A. annua (AAE) as an antimicrobial agent in vitro and to evaluate its chemopreventive efficacy in vivo in a small-cell lung cancer (SCLC) animal model. The dried powder of AAE was prepared using the Soxhlet extraction system from the leaves of Artemisia annua. The in vitro activity of AAE was determined against Candida albicans (C. albicans), Enterococcus faecalis (E. faecalis), Klebsiella pneumoniae (K. pneumoniae), and methicillin-resistant Staphylococcus aureus (MRSA) using the agar well diffusion method and propidium iodide (PI)-stained microbial death under a confocal microscope. The pretreatment of mice with AAE was initiated two weeks before the first dose of benzo[a]pyrene and continued for 21 weeks. The chemopreventive potential of the extract was evaluated by flow cytometry and biochemical and histopathological analyses of the tissues and serum accordingly, after sacrificing the mice. The data revealed the antimicrobial potential of AAE against all the species investigated, as it showed growth-inhibitory activity by MIC, as well as confocal microscopy. The pretreatment of AAE exhibited significant protection in carcinogen-modulated, average body weight (ABW), and relative organ weight (ROW) cancer biomarkers in the serum and antioxidants in the lungs. The hematoxylin and eosin (H&E) staining of the tissues revealed that AAE prevented malignancy in the lungs. AAE also induced apoptosis and decreased intracellular reactive oxygen species (ROS) in the lung cells analyzed by flow cytometry. The current findings demonstrated the use of AAE as an alternative medicine in the treatment of infectious disease and the chemoprevention of lung cancer. To our knowledge, this is the first study that summarizes the chemopreventive potential of AAE in a lung cancer model in vivo. However, further investigations are suggested to understand the role of AAE to potentiate the therapeutic index of the commercially available drugs that show multiple drug resistance against microbial growth and high toxicity during cancer chemotherapy.

Artificial Intelligence Predictive Models of Response to Cytotoxic Chemotherapy Alone or Combined to Targeted Therapy for Metastatic Colorectal Cancer Patients: A Systematic Review and Meta-Analysis

Tailored treatments for metastatic colorectal cancer (mCRC) have not yet completely evolved due to the variety in response to drugs. Therefore, artificial intelligence has been recently used to develop prognostic and predictive models of treatment response (either activity/efficacy or toxicity) to aid in clinical decision making. In this systematic review, we have examined the ability of learning methods to predict response to chemotherapy alone or combined with targeted therapy in mCRC patients by targeting specific narrative publications in Medline up to April 2022 to identify appropriate original scientific articles. After the literature search, 26 original articles met inclusion and exclusion criteria and were included in the study. Our results show that all investigations conducted on this field have provided generally promising results in predicting the response to therapy or toxic side-effects. By a meta-analytic approach we found that the overall weighted means of the area under the receiver operating characteristic (ROC) curve (AUC) were 0.90, 95% C.I. 0.80-0.95 and 0.83, 95% C.I. 0.74-0.89 in training and validation sets, respectively, indicating a good classification performance in discriminating response vs. non-response. The calculation of overall HR indicates that learning models have strong ability to predict improved survival. Lastly, the delta-radiomics and the 74 gene signatures were able to discriminate response vs. non-response by correctly identifying up to 99% of mCRC patients who were responders and up to 100% of patients who were non-responders. Specifically, when we evaluated the predictive models with tests reaching 80% sensitivity (SE) and 90% specificity (SP), the delta radiomics showed an SE of 99% and an SP of 94% in the training set and an SE of 85% and SP of 92 in the test set, whereas for the 74 gene signatures the SE was 97.6% and the SP 100% in the training set.

Cruciferous Vegetable Intake and Bulky DNA Damage within Non-Smokers and Former Smokers in the Gen-Air Study (EPIC Cohort)

Epidemiologic studies have indicated that cruciferous vegetables can influence the cancer risk; therefore, we examined with a cross-sectional approach the correlation between the frequent consumption of the total cruciferous vegetables and the formation of bulky DNA damage, a biomarker of carcinogen exposure and cancer risk, in the Gen-Air study within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. DNA damage measurements were performed in the peripheral blood of 696 of those apparently healthy without cancer controls, including 379 never-smokers and 317 former smokers from seven European countries by the 32P-postlabeling assay. In the Gen-Air controls, the median intake of cruciferous vegetables was 6.16 (IQR 1.16−13.66) g/day, ranging from 0.37 (IQR 0−6.00) g/day in Spain to 11.34 (IQR 6.02−16.07) g/day in the UK. Based on this information, participants were grouped into: (a) high consumers (>20 g/day), (b) medium consumers (3−20 g/day) and (c) low consumers (<3.0 g/day). Overall, low cruciferous vegetable intake was correlated with a greater frequency of bulky DNA lesions, including benzo(a)pyrene, lactone and quinone-adducts and bulky oxidative lesions, in the adjusted models. Conversely, a high versus low intake of cruciferous vegetables was associated with a reduction in DNA damage (up to a 23% change, p = 0.032); this was particularly evident in former smokers (up to a 40% change, p = 0.008). The Generalized Linear Regression models indicated an overall Mean Ratio between the high and the low consumers of 0.78 (95% confidence interval, 0.64−0.97). The current study suggests that a higher intake of cruciferous vegetables is associated with a lower level of bulky DNA adducts and supports the potential for cancer prevention strategies through dietary habit changes aimed at increasing the consumption of cruciferous vegetables.

Experimental and Theoretical Insights on Chemopreventive Effect of the Liposomal Thymoquinone Against Benzo[a]pyrene-Induced Lung Cancer in Swiss Albino Mice

Purpose

Thymoquinone (TQ), a phytoconstituent of Nigella sativa seeds, has been studied extensively in various cancer models. However, TQ’s limited water solubility restricts its therapeutic applicability. Our work aims to prepare the novel formulation of TQ and assess its chemopreventive potential in chemically induced lung cancer animal model.

Methods

The polyethylene glycol coated DOPE/CHEMS incorporating TQ-loaded pH-sensitive liposomes (TQPSL) were prepared and characterized. Mice were exposed to benzo[a]pyrene (BaP) thrice a week for 4 weeks to induce lung cancer. TQPSL was administered three times a week for 21 weeks, starting 2 weeks before the first dose of BaP.

Results

The prepared TQPSL revealed 85% entrapment efficiency with 128 nm size and −19.5 mv ζ-potential showing high stability of the formulation. The pretreatment of TQPSL showed the recovery in BaP-modulated relative organ weight of lungs, cancer marker enzymes, and antioxidant enzymes in the serum. The histopathological analysis of the tissues showed that TQPSL protected the malignancy in the lungs. The flow cytometry data revealed the induction of apoptosis and decreased intracellular ROS by TQPSL. Molecular docking was performed to predict the TQ’s affinity for eight possible anticancer drug targets linked to lung cancer etiology. The data assisted to identify the serine/threonine-protein kinase BRAF as the most suitable target of TQ with binding energy −6.8 kcal/mol.

Conclusion

The current findings demonstrated the potential of TQPSL and its possible therapeutic targets of lung cancer. To our knowledge, this is the first research to outline the development of TQ formulation against lung cancer considering its low solubility as well as pulmonary delivery challenges.

Association of genetic polymorphisms in DNA repair genes ERCC2 Asp312Asn (rs1799793), ERCC2 Lys 751 Gln (rs13181), XRCC1 Arg399 Gln (rs25487) and XRCC3 Thr 241Met (rs861539) with the susceptibility of lung cancer in Saudi population

This study demonstrated the association of polymorphisms in ERCC2 (Asp312Asn) rs1799793, ERCC2 (Lys751Gln) rs13181, XRCC1 (Arg399Gln) rs25487 and XRCC3(Thr241Met) rs861539 polymorphisms with a susceptibility of lung cancer (LC) onset in the Saudi population. The study was performed on 134 LC patients and 270 controls. The data revealed that there was no significant association of LC with subtype squamous cell carcinoma (SCC), small cell lung cancer (SCLC) and adenocarcinoma with the ERCC2 rs1799793 polymorphism. The data showed that the CC genotype for ERCC2 rs13181, the AA genotype for XRCC1 rs25487, and the genotype TT for XRCC3 rs861539 were significantly associated with SCC susceptibility (p < 0.05). Similarly, the CC genotype for ERCC2 rs13181 and the AA genotype for XRCC1 rs25487 were significantly associated with adenocarcinoma susceptibility (p < 0.05). Whereas, the TT genotype for XRCC3 rs861539 was significantly associated with SCLC susceptibility (p = 0.005). In total, significant association of LC susceptibility was found in the following combination models of recessive genotypes: AC heterozygous for ERCC2 rs13181 + AA homozygous for XRCC1 rs25487, CC homozygous for ERCC2 rs13181 + GA heterozygous for rs25487, CC homozygous for rs13181 + AA homozygous for XRCC1 rs25487, CC homozygous for ERCC2 rs13181 + TT homozygous for XRCC3 rs861539, GA heterozygous for XRCC1 rs25487 + CT heterozygous for XRCC3 rs861539, GA heterozygous for XRCC1 rs25487 + TT homozygous for XRCC3 rs861539, AA homozygous for XRCC1 rs25487 + CT heterozygous for XRCC3 rs861539, AA homozygous for XRCC1 rs25487+ TT homozygous for XRCC3 rs861539. These data clearly demonstrated that the combination of recessive genotypes may be associated with susceptibility of LC onset (p < 0.05). In short, the data indicated that DNA repair genes increase LC risk via gene-gene interaction rather than independent variants.

Epidemiologic evidence of exposure to polycyclic aromatic hydrocarbons and breast cancer: A systematic review and meta-analysis

Breast cancer (BC) is the most frequently diagnosed cancer in women. However, only 58% of cases have been associated with known risk factors (reproductive, hormonal, lifestyles, and genetic), and the rest to unknown causes. Nevertheless, growing evidence suggests that exposure to environmental contaminants is an important risk factor for BC. Polycyclic aromatic hydrocarbons (PAHs) are formed during organic matter combustion, including smoking, grilled meat, and fuels, and are important carcinogenic constituents of environmental pollution. We examined the information generated by epidemiological studies evaluating the association between BC and PAHs exposure from multiple sources. Our work was conducted according to Conducting Systematic Reviews and Meta-Analyses of Observational Studies of Etiology (COSMOS-E) guidelines. We searched PubMed, Web of Science, and Scopus from January 2000 to December 2019. A total of 124 records were identified, and only 23 articles met all inclusion criteria. Occupational and/or environmental exposure to PAHs was significantly associated with BC, irrespective of exposure being assessed by direct or indirect methods. CYP1A1 and CYP1B1 adverse polymorphisms, familial BC history and smoking status, significantly strengthened the association between PAHs exposure and BC, whereas high fruit and vegetable intake had antagonistic associations. The positive relationships obtained in the studies here reviewed indicated that PAHs exposure is a risk factor for BC. Research needs include the improvement of exposure assessment, particularly identification of specific PAHs, reconstruction of time-varying and distant past exposures and further studies on the interaction between known BC factors and modifiable diet and life-style factors allowing BC prevention and control.

Attenuation of Polycyclic Aromatic Hydrocarbon (PAH)-Mediated Pulmonary DNA Adducts and Cytochrome P450 (CYP)1B1 by Dietary Antioxidants, Omega-3 Fatty Acids, in Mice

Numerous human and animal studies have reported positive correlation between carcinogen-DNA adduct levels and cancer occurrence. Therefore, attenuation of DNA adduct levels would be expected to suppress tumorigenesis. In this investigation, we report that the antioxidants omega 3-fatty acids, which are constituents of fish oil (FO), significantly decreased DNA adduct formation by polycyclic aromatic hydrocarbons (PAHs). B6C3F1 male mice were fed an FO or corn oil (CO) diet, or A/J male mice were pre-fed with omega-3 fatty acids eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA). While the B6C3F1 mice were administered two doses of a mixture of seven carcinogenic PAHs including benzo(a)pyrene (BP), the A/J mice were treated i.p. with pure benzo[a]pyrene (BP). Animals were euthanized after 1, 3, or 7 d after PAH treatment. DNA adduct levels were measured by the ³²P-postlabeling assay. Our results showed that DNA adduct levels in the lungs of mice 7 d after treatment were significantly decreased in the FO or EPA/DHA groups compared with the CO group. Interestingly, both qPCR and Western blot analyses revealed that FO, DHA and EPA/DHA significantly decreased the expression of cytochrome P450 (CYP) 1B1. CYP1B1 plays a critical role in the metabolic activation of BP to DNA-reactive metabolites. qPCR also showed that the expression of some metabolic and DNA repair genes was induced by BP and inhibited by FO or omega-3 fatty acids in liver, but not lung. Our results suggest that a combination of mechanism entailing CYP1B1 inhibition and the modulation of DNA repair genes contribute to the attenuation of PAH-mediated carcinogenesis by omega 3 fatty acids.

Effect of EGCG on bronchial epithelial cell premalignant lesions induced by cigarette smoke and on its CYP1A1 expression

Epigallocatechin-3-gallate (EGCG) has been demonstrated to exhibit anticancer effects; however, the mechanisms behind these are not yet clear. The objective of the present study was to assess the effect of EGCG on smoking-induced, precancerous, bronchial epithelial cell lesions and determine a potential protective mechanism. Human bronchial epithelial (HBE) cells were treated with cigarette smoke extract (CSE). Benzopyrene-DNA adducts were detected by immunofluorescence cytochemistry. Changes to microRNA (miRNA) expression levels were detected via microarray. The effects of EGCG on smoke-induced benzopyrene-DNA adduct formation and the subsequent change in miRNA expression were analyzed. Subsequently, the protective effect of EGCG on smoke inhalation-induced precancerous lesions was investigated. The expression levels of miRNA target genes were also analyzed. After CSE treatment, benzopyrene-DNA adducts appeared in HBE cells, along with a resultant change in miRNA expression. EGCG inhibited the effects of CSE exposure; benzopyrene-DNA adduct formation was reduced and miRNA expression changes were suppressed. In vivo, EGCG significantly reduced benzopyrene-DNA adduct formation and the subsequent development of precancerous lesions in rat lungs induced by cigarette smoke inhalation. Moreover, EGCG downregulated CYP1A1 overexpression, a target gene of multiple smoking-induced miRNAs, in rat lungs. EGCG may reduce the risk of lung cancer by downregulating the expression of the key gene CYP1A1, preventing the formation of smoking-induced benzopyrene-DNA adducts and alleviating smoking-induced bronchial epithelial dysplasia and heterogeneity.

Downregulated Expression of CLEC9A as Novel Biomarkers for Lung Adenocarcinoma

Purpose

Abnormal CLEC9A expression is concerned with carcinogenesis. However, the role of CLEC9A in lung adenocarcinoma (LUAD) remains unknown. The goal of this study was to reveal the role of CLEC9A in LUAD based on bioinformatics and cellular functional experiments.

Materials and methods

Data available from The Cancer Genome Atlas (TCGA) were employed to study CLEC9A expression and mutations in LUAD. Expression and alterations of CLEC9A were analyzed using UALCAN and cBioPortal, respectively. Kaplan-Meier analysis was used to analyze the effect of CLEC9A on the survival of LUAD. Protein-protein interaction (PPI) network was built using GeneMANIA analysis. The similar genes of CLEC9A were obtained using GEPIA analysis, while co-expression genes correlated with CLEC9A were identified using LinkedOmics analysis. The effects of CLEC9A expression on immune cell infiltration was assessed. The effect of CLEC9A on the proliferation, apoptosis, cell cycle distribution, and invasion of human LUAD cells was detected in the LUAD cell line.

Results

CLEC9A was downregulated and the CLEC9A gene was often altered in LUAD. The survival of LUAD patients was correlated with the expression level of CLEC9A. The similar genes of CLEC9A were linked to functional networks involving positive regulation of interleukin-12 production, plasma membrane and CD40 receptor binding, primary immunodeficiency, intestinal immune network for IgA production, and cell adhesion molecules pathways. Cell cycle, apoptosis, EMT, and RAS/MAPK were significantly enriched pathways in positive and negative correlation genes with CLEC9A. A difference in the immune infiltration level of immune cell between the high and low CLEC9A expression groups was observed. Somatic cell copy number alternations (CNAs) of the CLEC9A, including arm-level gain and arm-level deletion, observably changed the infiltration levels of B cells, CD4+ T cells, macrophages, and neutrophils in LUAD. Except for LAG3, the expression of CD274, CTLA4, PDCD1, and TIGIT was positively correlated with the expression level of CLEC9A. After transfection, overexpression and knockdown of CLEC9A could affect the proliferation, apoptosis, cell cycle distribution, and invasion of LUAD cells.

Conclusion

CLEC9A is associated with prognosis and tumor immune microenvironment of LUAD, suggesting that CLEC9A may be considered as a novel biomarker for LUAD.

Clinicopathological and Prognostic Features of 67 Cases with Pulmonary Sarcomatoid Carcinoma: An 18-Year Single-Centre Experience

INTRODUCTION

Pulmonary sarcomatoid carcinoma (PSC) is a very rare subtype of non-small-cell lung cancer (NSCLC). It is frequently diagnosed in the advanced stage and is resistant to conventional chemotherapeutics. Due to the unique nature and rarity, we evaluated the epidemiological, clinicopathological, and survival data of PSC patients treated at our centre.

PATIENTS AND METHODS

We retrospectively collected demographic and clinical data of 67 PSC patients from a single tertiary referral hospital, between the 2000 and 2018. Univariate and multivariate analyses were performed to determine the risk factors affecting survival.

RESULTS

The median age was 61 years, and the percentage of male was 74.6%. Most of the patients had a smoking history (76.9%). The most common PSC subtype was pleomorphic carcinoma (46.3%). The median overall survival (OS) was 55.4 months, and the 5-year OS rate was 47.5%. Advanced stage, T4 tumour, and positive lymph node involvement were associated with poor OS (p < 0.05). The patients with negative epithelial markers had poorer prognosis (p = 0.027) and had more frequently stage IV disease (p = 0.016). Surgical treatment and stage IV disease were determined to be independent prognostic factors.

CONCLUSION

PSC is an extremely rare and aggressive variant of NSCLC. Positive epithelial markers may have favourable prognostic significance in PSC. Resection of the tumour with a negative surgical margin is crucial for better survival. The prognosis of the disease is very poor in the metastatic stage.

Concomitant and decoupled effects of cigarette smoke and SCAL1 upregulation on oncogenic phenotypes and ROS detoxification in lung adenocarcinoma cells

Lung cancer is the leading cause of cancer deaths worldwide, with smoking as its primary predisposing factor. Although carcinogens in cigarettes are known to cause oncogenic DNA alterations, analyses of patient cohorts revealed heterogeneous genetic aberrations with no clear driver mutations. The contribution of noncoding RNAs (ncRNAs) in the pathogenesis of lung cancer has since been demonstrated. Their dysregulation has been linked to cancer initiation and progression. A novel long noncoding RNA (lncRNA) called smoke and cancer-associated lncRNA 1 (SCAL1) was recently found upregulated in smoke-exposed adenocarcinomic alveolar epithelial cells. The present study characterized the phenotypic consequences of SCAL1 overexpression and knockdown using A549 cells as model system, with or without prior exposure to cigarette smoke extract (CSE). Increase in SCAL1 levels either by CSE treatment or SCAL1 overexpression led to increased cell migration, extensive cytoskeletal remodeling, and resistance to apoptosis. Further, SCAL1 levels were negatively correlated with intracellular levels of reactive oxygen species (ROS). In contrast, SCAL1 knockdown showed converse results for these assays. These results confirm the oncogenic function of SCAL1 and its role as a CSE-activated lncRNA that mediates ROS detoxification in A549 cells, thereby allowing them to develop resistance to and survive smoke-induced toxicity.

DNA damage in circulating leukocytes measured with the comet assay may predict the risk of death

The comet assay or single cell gel electrophoresis, is the most common method used to measure strand breaks and a variety of other DNA lesions in human populations. To estimate the risk of overall mortality, mortality by cause, and cancer incidence associated to DNA damage, a cohort of 2,403 healthy individuals (25,978 person-years) screened in 16 laboratories using the comet assay between 1996 and 2016 was followed-up. Kaplan–Meier analysis indicated a worse overall survival in the medium and high tertile of DNA damage (p < 0.001). The effect of DNA damage on survival was modelled according to Cox proportional hazard regression model. The adjusted hazard ratio (HR) was 1.42 (1.06–1.90) for overall mortality, and 1.94 (1.04–3.59) for diseases of the circulatory system in subjects with the highest tertile of DNA damage. The findings of this study provide epidemiological evidence encouraging the implementation of the comet assay in preventive strategies for non-communicable diseases.

M2 macrophage-derived exosomal long non-coding RNA AGAP2-AS1 enhances radiotherapy immunity in lung cancer by reducing microRNA-296 and elevating NOTCH2

Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) play vital roles in human diseases. We aimed to identify the effect of the lncRNA AGAP2 antisense RNA 1 (AGAP2-AS1)/miR-296/notch homolog protein 2 (NOTCH2) axis on the progression and radioresistance of lung cancer. Expression of AGAP2-AS1, miR-296, and NOTCH2 in lung cancer cells and tissues from radiosensitive and radioresistant patients was determined, and the predictive role of AGAP2-AS1 in the prognosis of patients was identified. THP-1 cells were induced and exosomes were extracted, and the lung cancer cells were respectively treated with silenced AGAP2-AS1, exosomes, and exosomes upregulating AGAP2-AS1 or downregulating miR-296. The cells were radiated under different doses, and the biological processes of cells were assessed. Moreover, the natural killing cell-mediated cytotoxicity on lung cancer cells was determined. The relationships between AGAP2-AS1 and miR-296, and between miR-296 and NOTCH2 were verified. AGAP2-AS1 and NOTCH2 increased while miR-296 decreased in radioresistant patients and lung cancer cells. The malignant behaviors of radioresistant cells were promoted compared with the parent cells. Inhibited AGAP2-AS1, macrophage-derived exosomes, and exosomes overexpressing AGAP2-AS1 or inhibiting miR-296 facilitated the malignant phenotypes of radioresistant lung cancer cells. Furthermore, AGAP2-AS1 negatively regulated miR-296, and NOTCH2 was targeted by miR-296. M2 macrophage-derived exosomal AGAP2-AS1 enhances radiotherapy immunity in lung cancer by reducing miR-296 and elevating NOTCH2. This study may be helpful for the investigation of radiotherapy of lung cancer.

M2 macrophages-derived exosomal microRNA-501-3p promotes the progression of lung cancer via targeting WD repeat domain 82

Background

Exosomes are known to transmit microRNAs (miRNAs) to affect cancer progression, while the role of M2 macrophages-derived exosomes (M2 exosomes) conveying miR-501-3p in lung cancer (LC) remains unknown. We aim to explore the role of exosomal miR-501-3p in LC development via targeting WD repeat domain 82 (WDR82).

Methods

Lung cancer tissue and normal tissue specimens were collected, in which tumor-associated macrophages (TAM) were measured by immunohistochemistry. M2 macrophages were induced and treated with altered miR-501-3p, and then the exosomes were extracted and identified. MiR-501-3p and WDR82 expression in LC tissues and cell liens was determined. The predictive role of miR-501-3p in prognosis of LC patients was assessed, and the proliferation, colony formation ability, invasion, migration and apoptosis of the LC cells were determined. Targeting relationship between miR-501-3p and WDR82 was confirmed.

Results

TAM level was elevated in lung cancer tissues. MiR-501-3p was upregulated while WDR82 was downregulated in LC tissues and cell lines, and the M2 exosomes further upregulated miR-501-3p. M2 exosomes and exosomal miR-501-3p promoted LC cell growth. MiR-501-3p inhibition reversed the effect of M2 exosomes on LC cells. WDR82 was confirmed as a target gene of miR-501-3p.

Conclusion

M2 macrophages-derived exosomal miR-501-3p promotes the progression of LC via downregulating WDR82.

Polycyclic Aromatic Hydrocarbon-induced Pulmonary Carcinogenesis in Cytochrome P450 (CYP)1A1- and 1A2-Null Mice: Roles of CYP1A1 and CYP1A2

In 2019, lung cancer was estimated to be the leading cause of cancer deaths in humans. Polycyclic aromatic hydrocarbons (PAHs) are known to increase the risk of lung cancer. PAHs are metabolized by the cytochrome P450 (CYP)1A subfamily, comprised of the CYP1A1 and 1A2 monooxygenases. These enzymes bioactivate PAHs into reactive metabolites that induce mutagenic DNA adducts, which can lead to cancer. Past studies have investigated the role of CYP1A1 in PAH bioactivation; however, the individual roles of each CYP1A enzyme are still unknown. In this investigation, we tested the hypothesis that mice lacking the genes for Cyp1a1 or Cyp1a2 will display altered susceptibilities to PAH-induced pulmonary carcinogenesis. Wild-type, Cyp1a1-null (Cyp1a1-/-), and Cyp1a2-null (Cyp1a2-/-) male and female mice were treated with 3-methylcholanthrene for cancer initiation and tumor formation studies. In wild-type mice, CYP1A1 and 1A2 expression was induced by 3-methylcholanthrene. Cyp1a1-/- and Cyp1a2-/- mice treated with PAHs displayed a compensatory pattern, where knocking out 1 Cyp1a gene led to increased expression of the other. Cyp1a1-/- mice were resistant to DNA adduct and tumor formation, whereas Cyp1a2-/- mice displayed increased levels of both. UALCAN analysis revealed that lung adenocarcinoma patients with high levels of CYP1A2 expression survive significantly better than patients with low/medium expression. In conclusion, Cyp1a1-/- mice were less susceptible to PAH-induced pulmonary carcinogenesis, whereas Cyp1a2-/- mice were more susceptible. In addition, high CYP1A2 expression was found to be protective for lung adenocarcinoma patients. These results support the need to develop novel CYP1A1 inhibitors to mitigate human lung cancer.

Ligation-Mediated Polymerase Chain Reaction Detection of 8-Oxo-7,8-Dihydro-2'-Deoxyguanosine and 5-Hydroxycytosine at the Codon 176 of the p53 Gene of Hepatitis C-Associated Hepatocellular Carcinoma Patients

Molecular mechanisms underlying Hepatitis C virus (HCV)-associated hepatocellular carcinoma (HCC) pathogenesis are still unclear. Therefore, we analyzed the levels of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) and other oxidative lesions at codon 176 of the p53 gene, as well as the generation of 3-(2-deoxy-β-d-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3H)-one deoxyguanosine (M₁dG), in a cohort of HCV-related HCC patients from Italy. Detection of 8-oxodG and 5-hydroxycytosine (5-OHC) was performed by ligation mediated-polymerase chain reaction assay, whereas the levels of M₁dG were measured by chromatography and mass-spectrometry. Results indicated a significant 130% excess of 8-oxodG at –TGC– position of p53 codon 176 in HCV-HCC cases as compared to controls, after correction for age and gender, whereas a not significant increment of 5-OHC at –TGC– position was found. Then, regression models showed an 87% significant excess of M₁dG in HCV-HCC cases relative to controls. Our study provides evidence that increased adduct binding does not occur randomly on the sequence of the p53 gene but at specific sequence context in HCV-HCC patients. By-products of lipid peroxidation could also yield a role in HCV-HCC development. Results emphasize the importance of active oxygen species in inducing nucleotide lesions at a p53 mutational hotspot in HCV-HCC patients living in geographical areas without dietary exposure to aflatoxin B₁.

Chromatographic Detection of 8-Hydroxy-2'-Deoxyguanosine in Leukocytes of Asbestos Exposed Workers for Assessing Past and Recent Carcinogen Exposures

Asbestos fibers include a group of silicate minerals that occur in the environment and are widely employed in occupational settings. Asbestos exposure has been associated to various chronic diseases; such as pulmonary fibrosis; mesothelioma; and lung cancer; often characterized by a long period of latency. Underlying mechanisms that are behind the carcinogenic effect of asbestos have not been fully clarified. Therefore; we have conducted an epidemiological study to evaluate the relationship between 8-hydroxy-2'-deoxyguanosine (8-oxodG), one of the most reliable biomarkers of oxidative stress and oxidative DNA damage; and asbestos exposure in the peripheral blood of residents in Tuscany and Liguria regions; Italy; stratified by occupational exposure to this carcinogen. Levels of 8-oxodG were expressed such as relative adduct labeling (RAL); the frequency of 8-oxodG per 105 deoxyguanosine was significantly higher among exposed workers with respect to the controls; i.e., 3.0 ± 0.2 Standard Error (SE) in asbestos workers versus a value of 1.3 ± 0.1 (SE) in unexposed controls (p < 0.001). When the relationship with occupational history was investigated; significant higher levels of 8-oxodG were measured in current and former asbestos workers vs. healthy controls; 3.1 ± 0.3 (SE) and 2.9 ± 0.2 (SE), respectively. After stratification for occupational history; a significant 194% excess of adducts was found in workers with 10 or more years of past asbestos exposure (p < 0.001). 8-oxodG can be used for medical surveillance programs of cohorts of workers with past and recent exposures to carcinogens for the identification of subjects requiring a more intense clinical surveillance.

The multi-faceted high order polymorphic synergistic interactions among nucleotide excision repair genes increase the risk of lung cancer in North Indians

It is evident that gene-gene interactions are pervasive in the determination of the susceptibility of human diseases. Polymorphisms in nucleotide excision repair pathway (NER) genes can cause variations in the repair capacity and therefore, might lead to increase in susceptibility towards lung cancer through complex gene-gene and gene-smoking interactions. Logistic regression analysis, along with high order genetic interaction were analyzed using data mining tools such as multifactor dimensionality reduction (MDR) and classification and regression tree analysis (CART). Overall, a protective effect was reported when a combinatorial effect of SNPs were studied by applying logistic regression analysis. Multifactor dimensionality reduction (MDR) analysis, revealed that the four factor model i.e. XPC K939Q, XPA 5'UTR, XPG F670W and XPG D1104H had the best ability to predict lung cancer risk (CVC = 100, p < 0.0001). While a two factor model, including smoking and XPG F670W suggested smoking was associated with the risk of developing lung cancer (CVC = 100, p < 0.0001). Individually XPG F670W was identified as the primary risk factor. In classification and regression tree analysis (CART), we observed a 6-fold risk for SCLC patients carrying XPA 5'UTR (M), XPD K751Q (W) (OR: 6.20; 95%CI: 2.40-16.01, p = 0.0001).Polymorphic NER genes might jointly modulate lung cancer risk through gene-gene and gene-smoking interaction.

AC138128.1 an Intronic lncRNA originating from ERCC1 Implies a Potential Application in Lung Cancer Treatment

Lung cancer is one of the most devastating tumors with a high incidence and mortality worldwide. Polymorphisms and expression of ERCC1 commonly predicted the occurrence and prognosis of lung cancer. However, few studies have focused on long non-coding RNAs related to ERCC1 though some studies reminded the importance of its post-transcriptional regulation. In the present study, an intronic lncRNA AC138128.1 originated from ERCC1 was firstly identified in microarray chip and database, and its possibility as a novel biomarker to predict lung cancer treatment was further discussed. Firstly, the qRT-PCR data showed that AC138128.1 expression was much lower in lung cancer comparing with its para-cancer tissues, which further analyzed by ROC curve. Similarly, the difference was also verified in 16HBE, A549 and LK₂ cells. Then AC138128.1 expression was found to have an increasing trend in a dose or time-dependent manner after cisplatin treatment. Finally, the subcellular distribution of AC138128.1 reminded that AC138128.1 was mainly expressed in the nucleus. Interestingly a positive relationship between AC138128.1 and ERCC1 expression was only found in cancer tissues, which reminded AC138128.1 may be involved in the regulation of ERCC1. Therefore, as a preliminary exploration of the lncRNA originated from ERCC1, the present study suggested AC138128.1 is of potential value in predicting platinum analogue benefit in lung cancer.

Houttuynia cordata Thunb. and its bioactive compound 2-undecanone significantly suppress benzo(a)pyrene-induced lung tumorigenesis by activating the Nrf2-HO-1/NQO-1 signaling pathway

Background

Lung cancer remains the most common cause of cancer-related deaths, with a high incidence and mortality in both sexes worldwide. Chemoprevention has been the most effective strategy for lung cancer prevention. Thus, exploring novel and effective candidate agents with low toxicity for chemoprevention is essential and urgent. Houttuynia cordata Thunb. (Saururaceae) (H. cordata), which is a widely used herbal medicine and is also popularly consumed as a healthy vegetable, exhibits anti-inflammatory, antioxidant and antitumor activity. However, the chemopreventive effect of H. cordata against benzo(a)pyrene (B[a]P)-initiated lung tumorigenesis and the underlying mechanism remain unclear.

Methods

A B[a]P-stimulated lung adenocarcinoma animal model in A/J mice in vivo and a normal lung cell model (BEAS.2B) in vitro were established to investigate the chemopreventive effects of H. cordata and its bioactive compound 2-undecanone against lung tumorigenesis and to clarify the underlying mechanisms.

Results

H. cordata and 2-undecanone significantly suppressed B[a]P-induced lung tumorigenesis without causing obvious systemic toxicity in mice in vivo. Moreover, H. cordata and 2-undecanone effectively decreased B[a]P-induced intracellular reactive oxygen species (ROS) overproduction and further notably protected BEAS.2B cells from B[a]P-induced DNA damage and inflammation by significantly inhibiting phosphorylated H2A.X overexpression and interleukin-1β secretion. In addition, H. cordata and 2-undecanone markedly activated the Nrf2 pathway to induce the expression of the antioxidative enzymes heme oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO-1). Nrf2 silencing by transfection with Nrf2 siRNA markedly decreased the expression of HO-1 and NQO-1 to diminish the reductions in B[a]P-induced ROS overproduction, DNA damage and inflammation mediated by H. cordata and 2-undecanone.

Conclusions

H. cordata and 2-undecanone could effectively activate the Nrf2-HO-1/NQO-1 signaling pathway to counteract intracellular ROS generation, thereby attenuating DNA damage and inflammation induced by B[a]P stimulation and playing a role in the chemoprevention of B[a]P-induced lung tumorigenesis. These findings provide new insight into the pharmacological action of H. cordata and indicate that H. cordata is a novel candidate agent for the chemoprevention of lung cancer.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1255-3) contains supplementary material, which is available to authorized users.

Bulky DNA adducts, microRNA profiles, and lipid biomarkers in Norwegian tunnel finishing workers occupationally exposed to diesel exhaust

OBJECTIVES

This study aimed to assess the biological impact of occupational exposure to diesel exhaust (DE) including DE particles (DEP) from heavy-duty diesel-powered equipment in Norwegian tunnel finishing workers (TFW).

METHODS

TFW (n=69) and referents (n=69) were investigated for bulky DNA adducts (by 32P-postlabelling) and expression of microRNAs (miRNAs) (by small RNA sequencing) in peripheral blood mononuclear cells (PBMC), as well as circulating free arachidonic acid (AA) and eicosanoid profiles in plasma (by liquid chromatography-tandem mass spectrometry).

RESULTS

PBMC from TFW showed significantly higher levels of DNA adducts compared with referents. Levels of DNA adducts were also related to smoking habits. Seventeen miRNAs were significantly deregulated in TFW. Several of these miRNAs are related to carcinogenesis, apoptosis and antioxidant effects. Analysis of putative miRNA-gene targets revealed deregulation of pathways associated with cancer, alterations in lipid molecules, steroid biosynthesis and cell cycle. Plasma profiles showed higher levels of free AA and 15-hydroxyeicosatetraenoic acid, and lower levels of prostaglandin D2 and 9-hydroxyoctadecadienoic acid in TFW compared with referents.

CONCLUSION

Occupational exposure to DE/DEP is associated with biological alterations in TFW potentially affecting lung homoeostasis, carcinogenesis, inflammation status and the cardiovascular system. Of particular importance is the finding that tunnel finishing work is associated with an increased level of DNA adducts formation in PBMC.