Search Results (49)

Background: DNA methylation alterations represent a key epigenetic mechanism linking environmental exposures to disease pathogenesis. The present study aimed to identify differentially methylated genes and shared biological processes associated with lung cancer (LuCa), chronic obstructive pulmonary disease (COPD) and tobacco exposure. Methods: A comprehensive literature search was performed in PubMed to identify studies evaluating DNA methylation in LuCa, COPD and smoking-related models. A total of 117 articles were selected, including 83 studies on lung cancer, 18 on COPD and 16 on smoking exposure. Genes exhibiting statistically significant methylation changes relative to controls were extracted from each study. To provide additional support for these findings, differential methylation signatures were further evaluated using The Cancer Genome Atlas (TCGA) lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) datasets. Functional and transcription factor motif enrichment analyses were subsequently conducted to identify shared biological pathways and regulatory mechanisms. Results: In total, 324 genes displaying altered methylation patterns across these conditions were identified. Seven tumor suppressor genes (CDKN2A, CDH13, MGMT, MIR137, DAPK1, RARB, and RASSF1A) consistently exhibited hypermethylation in both lung cancer and in association with smoking exposure. In addition, AHRR hypomethylation emerged as a shared epigenetic hallmark across all three conditions. TCGA-based analyses confirmed several of these methylation patterns and revealed subtype-specific methylation profiles associated with smoking history. Functional enrichment highlighted common biological processes and signaling pathways, particularly those related to transcriptional regulation, apoptosis and cancer-associated pathways. Conclusions: These results provide an integrative overview of shared DNA methylation alterations associated with smoking exposure, COPD, and lung cancer, and suggest potential DNA methylation candidates that may be relevant for future biomarker development and mechanistic studies. Full article

Background/Objectives: Wildfires are increasing in frequency and intensity worldwide, leading to widespread exposure to wildfire smoke and associated environmental stressors. While the respiratory and cardiovascular effects of wildfire smoke are well established, the potential neurological and mental health consequences have received growing attention. This narrative review synthesizes evidence from animal and human studies examining the effects of wildfire exposure on neurological function, behavior, and mental health, and explores the potential role of epigenetic mechanisms. Methods: A structured literature search was conducted using PubMed to identify original research articles examining wildfire exposure in relation to neurological, behavioral, mental health, or epigenetic outcomes. Both human and animal studies were included. Results: Experimental animal studies suggest that wildfire smoke exposure can induce neuroinflammation, blood–brain barrier disruption, metabolic alterations, and behavioral changes. Human studies conducted in wildfire-affected populations frequently report an elevated prevalence of depression, anxiety, post-traumatic stress disorder (PTSD), and sleep disturbances. However, many of these studies reflect mental health outcomes associated with wildfire disaster exposure, including evacuation and psychosocial stress, whereas only a subset of studies quantify wildfire smoke or PM_2.5 exposure. Emerging evidence from both animal models and human studies indicates that wildfire exposure may be associated with changes in epigenetic regulation, including alterations in DNA methylation and miRNA expression. Conclusions: Current evidence suggests that wildfire exposure may influence neurological and mental health outcomes through biological and psychosocial pathways. However, the literature remains heterogeneous, and the independent effects of wildfire smoke exposure are often difficult to disentangle from disaster-related stressors. In addition, human evidence linking wildfire exposure to epigenetic changes remains limited, restricting causal inference. Further longitudinal and mechanistic studies integrating exposure assessment, neurological outcomes, and molecular profiling are needed to clarify these relationships. Full article

Lung squamous cell carcinoma (LUSC) tends to arise in the setting of interstitial or emphysematous lung diseases, including idiopathic pulmonary fibrosis (IPF), pulmonary emphysema (PE), and smoking-related interstitial fibrosis (SRIF), where field cancerization may extend. DNA methylation of promoter regions of p16, CDH13, and RASSF1A and p16 exon 2 was assessed by methylation-specific PCR. Tumor, adjacent (<3 cm), and distant (≥3 cm) lung tissues were obtained from 25 patients with LUSC (IPF, n = 7; PE, n = 8; SRIF, n = 10). p16 exon 2 methylation was significantly higher in tumors than in non-tumorous tissues in PE and SRIF cases. In contrast, IPF cases showed p16 exon 2 hypermethylation also in distant tissues. Across tumor samples, p16 promoter hypermethylation was frequently observed in stage II or higher. p16 expression in tumors was generally reduced in IPF and PE cases, compared with SRIF cases. No consistent methylation or expression patterns were observed for CDH13 or RASSF1A. p16-associated molecular alterations exhibited disease- and stage-related differences, suggesting heterogeneity in LUSC carcinogenesis. These findings indicate a broader epigenetic field effect, as reflected by p16 exon 2, in IPF-associated LUSC and suggest that complex, elusive mechanisms underlying p16 aberrations may contribute to this phenomenon. Full article

Background/Objectives: Although O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation is a key predictive biomarker in glioblastoma, its association with clinical and lifestyle characteristics remains poorly understood. Methods: We retrospectively analyzed 105 patients who underwent surgical treatment for glioblastoma at Kyungpook National University Hospital between August 2012 and April 2022 to evaluate the relationship between MGMT promoter methylation status and clinical and lifestyle factors. Collected variables included age, sex, body weight, body height, smoking history, and comorbidities such as hypertension, diabetes mellitus, and hyperlipidemia. Results: Current smoking was significantly associated with MGMT promoter methylation in both univariate and multivariate analyses (adjusted odds ratio [OR], 4.6; p = 0.03). Additionally, a history of hypertension was associated with MGMT promoter methylation after multivariate adjustment (adjusted OR, 3.6; p = 0.03). Conclusions: MGMT promoter methylation in glioblastoma was associated with current smoking and a history of hypertension, suggesting lifestyle-related factors may influence epigenetic mechanisms underlying MGMT promoter methylation in glioblastoma. Full article

Background/Objectives: Coupled with the already-problematic background rates of traditional cigarette consumption during pregnancy, the surging epidemic of electronic cigarette usage among pregnant women redoubles the importance of understanding the impacts of nicotine exposure during critical periods of development. To date, a burgeoning body of human epidemiological and animal model research indicates that not only the children but also the grandchildren of maternal smokers are at higher risk for neurodevelopmental disorders such as ADHD, autism, and schizophrenia and are predisposed to neurodevelopmental abnormalities which transcend these diagnoses. However, the roles of discrete cellular sub-populations in these and other intergenerational consequences of smoking during pregnancy remain indeterminate. Methods: Toward the resolution of this void in the literature, the present study characterized alterations in the gene expression profiles of dopamine receptor D1-expressing striatal cells from the first- and second-generation male progeny of female mice that were continuously exposed to nicotine beginning prior to conception, continuing throughout pregnancy, and concluding upon weaning of offspring. Results: Dopamine receptor D1-expressing striatal cells from our mouse models of the children and grandchildren of maternal smokers exhibit differential expression patterns for a multitude of genes that are (1) individually associated with neurodevelopmental disorders, (2) collectively overrepresented in gene set annotations related to brain, behavioral, neurobiological, and epigenomic phenotypes shared among neurodevelopmental disorders, and (3) orthologous to human genes that exhibit differential DNA methylation signatures in the newborns of maternal smokers. Conclusions: Together with our and others’ previous findings, the results of this study support the emerging theory that, by inducing extensive alterations in gene expression that in turn elicit cascading neurobiological changes which ultimately confer widespread neurobehavioral abnormalities, nicotine-induced epigenomic dysregulation may be a primary driver of neurodevelopmental deficits and disorders in the children and grandchildren of maternal smokers. Full article

Cigarette smoking is the leading preventable cause of chronic diseases (e.g., COPD, cardiovascular disease, cancer), largely driven by persistent immune-inflammatory mechanisms. This review synthesizes the molecular and cellular cascades linking cigarette smoke (CS) exposure to chronic pathology. CS constituents, particularly ROS/RNS, induce rapid oxidative stress that overwhelms antioxidant defenses and generates damage-associated molecular patterns (DAMPs). These DAMPs activate pattern recognition receptors (PRRs) and the NLRP3 inflammasome, initiating NF-κB signaling and the release of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6). CS exposure causes profound innate immune dysregulation, including airway epithelial barrier disruption, hyperactivated neutrophils, and dysfunctional alveolar macrophages (AMs) that release destructive proteases (e.g., MMP-12) and acquire foam-cell–like characteristics. Furthermore, CS drives adaptive immunity toward a Th1/Th17-dominant phenotype while suppressing regulatory T-cell (Treg) function, thereby promoting autoimmunity and chronic tissue injury. Critically, CS induces epigenetic reprogramming (e.g., DNA methylation, miRNA dysregulation), locking immune cells into a persistent pro-inflammatory state. This convergence of oxidative stress, innate and adaptive immune dysregulation, and epigenetic alterations underlies the systemic low-grade inflammation that fuels smoking-related chronic diseases, highlighting key targets for novel therapeutic interventions. Full article

Background: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths worldwide, increasingly arising in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). Epigenetic dysregulation, particularly DNA methylation, has been implicated in MASLD-HCC development, yet the roles that the principal DNA methylation precursor metabolites, S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH), play in this association are unclear. Objective: We investigated associations of circulating SAM, SAH, the SAM/SAH ratio, with MASLD-HCC. Methods: In a multi-center pilot case–control study, we evaluated 69 MASLD-HCC cases and 136 cancer-free MASLD controls. Plasma SAM and SAH levels were quantified by liquid chromatography–tandem mass spectrometry. Metabolite levels were categorized as greater than or less than the median based on distribution in controls. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for age, sex, body mass index, smoking status, and type 2 diabetes. Results: MASLD-HCC cases had significantly higher plasma SAM levels (mean 121 vs. 96 nmol/L; p = 0.001) and SAM/SAH ratios (2.09 vs. 1.48; p = 6.42 × 10⁻⁷) than MASLD controls. In multivariable-adjusted models, elevated SAM levels (OR_{≥median vs. <median} = 2.76; 95% CI: 1.38–5.72) and higher SAM/SAH ratio (OR_{≥median vs. <median} = 2.30; 95% CI: 1.15–4.73) were associated with higher odds of MASLD-HCC. SAH alone was associated with MASLD-HCC. Conclusions: Higher plasma SAM levels and SAM/SAH ratios are independently linked to MASLD-HCC development. These metabolites might serve as noninvasive markers for HCC risk stratification in patients with MASLD and improve early detection efforts for MASLD-HCC. Full article

Introduction: Cigarette smoking is unquestionably associated with an increase in morbidity and mortality worldwide, exerting significant adverse effects on respiratory health. The impact of tobacco persists in the epigenome long after smoking cessation. Furthermore, the offspring of smokers may also be affected by the detrimental effects of smoking. Material and methods: The modifications made to the body, such as DNA methylation, histone modification, and regulation by non-coding RNAs, do not change the DNA sequence but can influence gene expression. In respiratory disease, multigenerational effects have been reported in humans, with an increased risk of asthma or COPD and decreased lung function in offspring, despite them not being exposed to smoke. Prenatal nicotine exposure leads to pulmonary pathology that persists across three consecutive generations, supported by animal studies conducted by Rehan et al. Significant advances in high-throughput genomic and epigenomic technologies have enabled the discovery of molecular phenotypes. These either reflect or are influenced by them. Due to the hidden environmental effects and the rise of artificial intelligence (AI) in biomedical research, new predictive models are emerging that not only explain complex data but also enable earlier detection and prevention of smoking-related diseases. In this narrative review, we synthesise the latest research on how smoking affects gene regulation and chromatin structure, emphasising how tobacco can increase vulnerability to multiple diseases. Discussion: For many years, it was widely believed that diseases are solely inherited through genetics. However, recent research in epigenetics has led to a significant realisation: environmental factors play a crucial role in an individual’s life. External influences leave a mark on DNA that can influence future health and offer insights into potential illnesses. In this context, it is possible that in the future, doctors might treat people not as a whole but as individual beings, with personalised medication, tests, and other approaches. Conclusions: The accumulated evidence suggests that exposure to various environmental factors is associated with multigenerational changes in gene expression patterns, which may contribute to increased disease risk. The application of artificial intelligence in this domain is currently a crucial tool for researching potential future health issues in individuals, and it holds a powerful prospect that could transform current medical and scientific practice. Full article

Lung cancer remains the leading cause of cancer-related deaths worldwide, driven by its complexity and the heterogeneity of its subtypes, which influence pathogenesis, tumor microenvironment, and genetic alterations. We developed a novel weighted gene regulatory network reconstruction method based on maximum entropy and Markov chain entropy principles, which integrates gene expression and DNA methylation data to generate biologically informed networks. Applied to LUAD and LUSC datasets, we define a network methylation index to determine whether gene methylation acts as oncogenic or tumor-suppressive. By revealing a stable core set of pathogenic genes, we identify not only genes with significant expression changes, such as CD74 and HGF, but also pathogenic genes with stable expression, such as BRAF and KDM6A. Additionally, we uncover potential driver genes, such as CORO2B and C20orf194, associated with disease stage, gender, and smoking status. This method offers a more comprehensive understanding of NSCLC mechanisms, paving the way for improved therapeutic strategies. Full article

Background/Objectives: Gastric cancer is one of the leading malignancies worldwide. B vitamins play important roles in DNA synthesis and methylation because they are considered co-enzymes in one-carbon metabolism. There is inconclusive evidence regarding the associations between dietary vitamins B₁, B₂, and B₆ with the risk of gastric cancer in different epidemiologic studies. We, therefore, investigated such associations in a hospital-based case-control study comprising 1182 incident cases of gastric cancer and 2995 controls in Vietnam. Methods: Dietary vitamins B₁, B₂, and B₆ were derived from a semi-quantitative validated food frequency questionnaire. An unconditional logistic regression model was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for the risk of gastric cancer in relation to dietary intake of vitamins B₁, B₂, and B₆. Results: Overall, dietary vitamins B₁ (OR_{per-SD increment} = 0.83; 95% CI: 0.78–0.89; P_trend < 0.001) and B₆ (OR_{per-SD increment} = 0.88; 95% CI: 0.81–0.94; P_trend < 0.001) were associated with a reduced risk of gastric cancer. Compared with the lowest quintile, the ORs (95% CIs) of gastric cancer for quintiles 2, 3, 4, and 5 of the vitamin B₁ intake were 0.64 (0.51–0.79), 0.54 (0.43–0.69), 0.57 (0.44–0.74), and 0.42 (0.31–0.55), respectively; for vitamin B₆ intake, quintiles 2, 3, 4, and 5 were 0.53 (0.42–0.66), 0.54 (0.42–0.70), 0.61 (0.46–0.81), and 0.46 (0.33–0.63), respectively. This inverse association was not different across sex, BMI, and smoking statuses. No association was found between dietary vitamin B₂ and gastric cancer risk. Conclusions: Dietary vitamins B₁ and B₆ were associated with a reduced risk of gastric cancer in the Vietnamese population. Future studies are warranted to replicate our findings, which also have great implications for gastric cancer prevention and control programs in low- and middle-income countries. Full article

The collapse of the World Trade Center (WTC) buildings in New York City generated a large plume of dust and smoke. WTC dust contained human carcinogens including metals, asbestos, polycyclic aromatic hydrocarbons (PAHs), persistent organic pollutants (POPs, including polychlorinated biphenyls (PCBs) and dioxins), and benzene. Excess levels of many of these carcinogens have been detected in biological samples of WTC-exposed persons, for whom cancer risk is elevated. As confirmed in this structured literature review (n studies = 80), all carcinogens present in the settled WTC dust (metals, asbestos, benzene, PAHs, POPs) have previously been shown to be associated with DNA methylation dysregulation of key cancer-related genes and pathways. DNA methylation is, therefore, a likely molecular mechanism through which WTC exposures may influence the process of carcinogenesis. Full article

Despite extensive research on 5-methylcytosine (5mC) in relation to smoking, there has been limited exploration into the interaction between smoking and 5-hydroxymethylcytosine (5hmC). In this study, total DNA methylation (5mC+5hmC), true DNA methylation (5mC) and hydroxymethylation (5hmC) levels were profiled utilizing conventional bisulphite (BS) and oxidative bisulphite (oxBS) treatment, measured with the Illumina Infinium Methylation EPIC BeadChip. An epigenome-wide association study (EWAS) of 5mC+5hmC methylation revealed a total of 38,575 differentially methylated positions (DMPs) and 2023 differentially methylated regions (DMRs) associated with current smoking, along with 82 DMPs and 76 DMRs associated with former smoking (FDR-adjusted p < 0.05). Additionally, a focused examination of 5mC identified 33 DMPs linked to current smoking and 1 DMP associated with former smoking (FDR-adjusted p < 0.05). In the 5hmC category, eight DMPs related to current smoking and two DMPs tied to former smoking were identified, each meeting a suggestive threshold (p < 1 × 10⁻⁵). The substantial number of recognized DMPs, including 5mC+5hmC (7069/38,575, 2/82), 5mC (0/33, 1/1), and 5hmC (2/8, 0/2), have not been previously reported. Our findings corroborated previously established methylation positions and revealed novel candidates linked to tobacco smoking. Moreover, the identification of hydroxymethylated CpG sites with suggestive links provides avenues for future research. Full article

Allergic diseases are one of the most common chronic conditions and their prevalence is on the rise. Environmental exposure, primarily prenatal and early life influences, affect the risk for the development and specific phenotypes of allergic diseases via epigenetic mechanisms. Exposure to pollutants, microorganisms and parasites, tobacco smoke and certain aspects of diet are known to drive epigenetic changes that are essential for immune regulation (e.g., the shift toward T helper 2-Th2 cell polarization and decrease in regulatory T-cell (Treg) differentiation). DNA methylation and histone modifications can modify immune programming related to either pro-allergic interleukin 4 (IL-4), interleukin 13 (IL-13) or counter-regulatory interferon γ (IFN-γ) production. Differential expression of small non-coding RNAs has also been linked to the risk for allergic diseases and associated with air pollution. Certain exposures and associated epigenetic mechanisms play a role in the susceptibility to allergic conditions and specific clinical manifestations of the disease, while others are thought to have a protective role against the development of allergic diseases, such as maternal and early postnatal microbial diversity, maternal helminth infections and dietary supplementation with polyunsaturated fatty acids and vitamin D. Epigenetic mechanisms are also known to be involved in mediating the response to common treatment in allergic diseases, for example, changes in histone acetylation of proinflammatory genes and in the expression of certain microRNAs are associated with the response to inhaled corticosteroids in asthma. Gaining better insight into the epigenetic regulation of allergic diseases may ultimately lead to significant improvements in the management of these conditions, earlier and more precise diagnostics, optimization of current treatment regimes, and the implementation of novel therapeutic options and prevention strategies in the near future. Full article

Colorectal cancer is the second leading cause of cancer-related mortality worldwide. Numerous pathophysiological mechanisms, such as abnormal cell proliferation, cell differentiation, resistance to apoptosis, invasion of structures adjacent to colorectal tumor cells, and distant metastasis, are involved in colorectal carcinogenesis. These processes are initiated by the complex interaction of a number of genetic and environmental factors, including sedentary lifestyle, obesity, alcohol consumption, smoking, or gut microbiota. Despite the significant progress achieved in the diagnostic and therapeutic management of patients with colorectal cancer, there has been recently a noteworthy increase in the incidence of colorectal cancer in individuals below the age of 50 years. Early-onset colorectal cancer has a different frequency of oncogenic mutations, a higher prevalence of mucinous histology, a distinct deoxyribonucleic acid (DNA) methylation profile, a more distal location, and lower survival rates. A significant improvement in the prognosis of these patients can be achieved through the detection and removal of modifiable risk factors, along with the implementation of personalized screening strategies for individuals at high risk for this malignancy. Furthermore, gaining comprehension of the pathophysiological mechanisms by which these risk factors contribute to the process of oncogenesis may facilitate the discovery of novel therapeutic targets. Full article

DNA methylation (DNAm) is a dynamic, age-dependent epigenetic modification that can be used to study interactions between genetic and environmental factors. Environmental exposures during critical periods of growth and development may alter DNAm patterns, leading to increased susceptibility to diseases such as asthma and allergies. One method to study the role of DNAm is the epigenetic clock—an algorithm that uses DNAm levels at select age-informative Cytosine-phosphate-Guanine (CpG) dinucleotides to predict epigenetic age (EA). The difference between EA and calendar age (CA) is termed epigenetic age acceleration (EAA) and reveals information about the biological capacity of an individual. Associations between EAA and disease susceptibility have been demonstrated for a variety of age-related conditions and, more recently, phenotypes such as asthma and allergic diseases, which often begin in childhood and progress throughout the lifespan. In this review, we explore different epigenetic clocks and how they have been applied, particularly as related to childhood asthma. We delve into how in utero and early life exposures (e.g., smoking, air pollution, maternal BMI) result in methylation changes. Furthermore, we explore the potential for EAA to be used as a biomarker for asthma and allergic diseases and identify areas for further study. Full article