The level of free-circulating mtDNA in patients with radon-induced lung cancer

The role of exosomal hsa-miR-125b-5p and hsa-miR-320c as non-invasive biomarkers in high-radon areas of Kazakhstan

BACKGROUND

Radon, a radioactive gas, is a significant risk factor for lung cancer, especially in non-smokers. This study examines the expression of exosomal microRNAs (miRNAs) as potential biomarkers for radon-induced effects.

METHODS

A total of 109 participants from high- and low-radon areas in Kazakhstan were included. Exosomal hsa-miR-125b-5p and hsa-miR-320c levels were quantified using real-time PCR.

RESULTS

Results revealed a 25.4-fold increase in hsa-miR-125b-5p and a 12.5-fold decrease in hsa-miR-320c in participants exposed to high-radon levels compared to controls. Bioinformatic analysis identified key target genes, such as PRDM1 and IRF4, which are implicated in cancer development.

CONCLUSION

These findings suggest that exosomal miRNAs could serve as non-invasive biomarkers for radon exposure, offering potential for early diagnosis and monitoring of radon-induced lung cancer. The study underscores the need for further research to validate these miRNAs as reliable diagnostic tools.

Aberrant fragmentomic features of circulating cell-free mitochondrial DNA as novel biomarkers for multi-cancer detection

Fragmentomic features of circulating cell free mitochondrial DNA (ccf-mtDNA) including fragmentation profile, 5' end base preference and motif diversity are poorly understood. Here, we generated ccf-mtDNA sequencing data of 1607 plasma samples using capture-based next generation sequencing. We firstly found that fragmentomic features of ccf-mtDNA were remarkably different from those of circulating cell free nuclear DNA. Furthermore, region-specific fragmentomic features of ccf-mtDNA were observed, which was associated with protein binding, base composition and special structure of mitochondrial DNA. When comparing to non-cancer controls, six types of cancer patients exhibited aberrant fragmentomic features. Then, cancer detection models were built based on the fragmentomic features. Both internal and external validation cohorts demonstrated the excellent capacity of our model in distinguishing cancer patients from non-cancer control, with all area under curve higher than 0.9322. The overall accuracy of tissue-of-origin was 89.24% and 87.92% for six cancer types in two validation cohort, respectively. Altogether, our study comprehensively describes cancer-specific fragmentomic features of ccf-mtDNA and provides a proof-of-principle for the ccf-mtDNA fragmentomics-based multi-cancer detection and tissue-of-origin classification.

Transcriptomic analysis reveals transcription factors implicated in radon-induced lung carcinogenesis

Background

Radon, a potent carcinogen, is a significant catalyst for lung cancer development. However, the molecular mechanisms triggering radon-induced lung cancer remain elusive.

Methods

Utilizing a radon exposure concentration of 20,000 Bq/m3 for 20 min/session, malignant transformation was induced in human bronchial epithelial cells (BEAS-2B).

Results

Radon-exposed cells derived from passage 25 (BEAS-2B-Rn) exhibited enhanced proliferation and increased colony formation. Analysis of differential gene expression (DEG) through transcription factors revealed 663 up-regulated and 894 down-regulated genes in radon-exposed cells. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed significant alterations in the malignant transformation pathway of cells, including those related to cancer and the PI3K/AKT signaling pathway. A PPI network analysis indicated a significant association of oncogenes, such as CCND1, KIT, and GATA3, with lung cancer among differentially expressed genes. In addition, the stability of the housekeeping gene was determined through RT-qPCR analysis, which also confirmed the results of transcriptome analysis.

Conclusions

The results suggest that transcription factors may play a pivotal role in conferring a survival advantage to radon-exposed cells. This is achieved by malignant transformation of human bronchial epithelial cells into lung carcinogenesis cell phenotypes.

Radiation-Induced miRNAs Changes and cf mtDNA Level in Trauma Surgeons: Epigenetic and Molecular Biomarkers of X-ray Exposure

Exposure to ionizing radiation can result in the development of a number of diseases, including cancer, cataracts and neurodegenerative pathologies. Certain occupational groups are exposed to both natural and artificial sources of radiation as a consequence of their professional activities. The development of non-invasive biomarkers to assess the risk of exposure to ionizing radiation for these groups is of great importance. In this context, our objective was to identify epigenetic and molecular biomarkers that could be used to monitor exposure to ionizing radiation. The impact of X-ray exposure on the miRNAs profile and the level of cf mtDNA were evaluated using the RT-PCR method. The levels of pro-inflammatory cytokines in their blood were quantified using the ELISA method. A significant decrease in miR-19a-3p, miR-125b-5p and significant increase in miR-29a-3p was observed in the blood plasma of individuals exposed to X-ray. High levels of pro-inflammatory cytokines and cf mtDNA were also detected. In silico identification of potential targets of these miRNAs was conducted using MIENTURNET. VDAC1 and ALOX5 were identified as possible targets. Our study identified promising biomarkers such as miRNAs and cf mtDNA that showed a dose-dependent effect of X-ray exposure.

Increased levels of circulating cell-free DNA in COVID-19 patients with respiratory failure

Cell-free DNA (cfDNA) is released from injured cells and aggravates inflammation. Patients with coronavirus disease (COVID-19) often develop pneumonia and respiratory failure, and require oxygen therapy (OT), including mechanical ventilation (MV). It remains unclear whether cfDNA predicts the risk of receiving OT or MV in COVID-19 patients. Therefore, we hypothesized that circulating cfDNA levels could reflect the severity of respiratory failure and determine a therapeutic approach for oxygenation in patients with COVID-19. We analyzed cfDNA levels in serum samples from 95 hospitalized patients with COVID-19 at Showa University Hospital (Tokyo, Japan). cfDNA levels were assessed by measuring the copy numbers of mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) using quantitative real-time PCR (qPCR). Both cf-nDNA and cf-mtDNA levels were negatively correlated with adjusted SpO2 for FiO2 (SpO2/FiO2 ratio). Elevated cf-nDNA and cf-mtDNA levels were associated with the requirement for OT or MV during patient admission. Multivariate logistic regression analysis revealed that cf-nDNA and cf-mtDNA levels were independent risk factors for OT and MV. These results suggest that both serum cf-nDNA and cf-mtDNA could serve as useful early biomarkers to indicate the necessity of OT or MV in patients with COVID-19.

Biomarkers in Thyroid Cancer: Emerging Opportunities from Non-Coding RNAs and Mitochondrial Space

Thyroid cancer diagnosis primarily relies on imaging techniques and cytological analyses. In cases where the diagnosis is uncertain, the quantification of molecular markers has been incorporated after cytological examination. This approach helps physicians to make surgical decisions, estimate cancer aggressiveness, and monitor the response to treatments. Despite the availability of commercial molecular tests, their widespread use has been hindered in our experience due to cost constraints and variability between them. Thus, numerous groups are currently evaluating new molecular markers that ultimately will lead to improved diagnostic certainty, as well as better classification of prognosis and recurrence. In this review, we start reviewing the current preoperative testing methodologies, followed by a comprehensive review of emerging molecular markers. We focus on micro RNAs, long non-coding RNAs, and mitochondrial (mt) signatures, including mtDNA genes and circulating cell-free mtDNA. We envision that a robust set of molecular markers will complement the national and international clinical guides for proper assessment of the disease.

A state-of-the-science review of using mitochondrial DNA copy number as a biomarker for environmental exposure

Mitochondria are bioenergetic, biosynthetic, and signaling organelles in eukaryotes, and contain their own genomes, mitochondrial DNA (mtDNA), to supply energy to cells by generating ATP via oxidative phosphorylation. Therefore, the threat to mitochondria' integrity and health resulting from environmental exposure could induce adverse health effects in organisms. In this review, we summarized the association between mtDNA copy number (mtDNAcn), and environmental exposures as reported in the literature. We conducted a literature search in the Web of Science using [Mitochondrial DNA copy number] and [Exposure] as two keywords and employed three selection criteria for the final inclusion of 97 papers for review. The consensus of data was that mtDNAcn could be used as a plausible biomarker for cumulative exposures to environmental chemical and physical agents. In order to furtherly expand the application of mtDNAcn in ecological and environmental health research, we suggested a series of algorithms aiming to standardize the calculation of mtDNAcn based on the PCR results in this review. We also discussed the pitfalls of using whole blood/plasma samples for mtDNAcn measurements and regard buccal cells a plausible and practical alternative. Finally, we recognized the importance of better understanding the mechanistic analysis and regulatory mechanism of mtDNAcn, in particular the signals release and regulation pathways. We believe that the development of using mtDNAcn as an exposure biomarker will revolutionize the evaluation of chronic sub-lethal toxicity of chemicals to organisms in ecological and environmental health research that has not yet been implemented.

Causal relationships between mitochondrial proteins and different pathological types of lung cancer: a bidirectional mendelian randomization study

An increasing number of studies point to an association between mitochondrial proteins (MPs) and lung cancer (LC). However, the causal relationship between MPs and LC remains unclear. Consequently, our study employed a bidirectional Mendelian randomization (MR) analysis to explore the causal association between MPs and different pathological types of LC. A two-sample MR study was performed using the genome-wide association study (GWAS) data publicly available. We applied the primary inverse variance weighted (IVW) method along with additional MR methods to validate the causality between MPs and different pathological types of LC. To ensure the robustness of our findings, sensitivity analyses were employed. Moreover, we performed a bi-directional MR analysis to determine the direction of the causal association. We identified a total of seven MPs had significant causal relationships on overall LC, lung squamous cell carcinoma (LUSC), and small cell lung carcinoma (SCLC). We found two MPs had significant associations with overall LC, four MPs had significant associations with LUSC, and four MPs had significant associations with SCLC. Additionally, an MP was found to have a nominal relationship with LUSC. Moreover, no causality was found between MPs and lung adenocarcinoma (LUAD). Bidirectional MR showed no reverse effect between identified MPs and different pathological types of LC. In general, our findings of this MR study suggest causal associations of specific MPs with overall LC, LUSC, and SCLC. However, no such causality was found in LUAD.

The Molecular Mechanisms in Senescent Cells Induced by Natural Aging and Ionizing Radiation

This review discusses the relationship between cellular senescence and radiation exposure. Given the wide range of ionizing radiation sources encountered by people in professional and medical spheres, as well as the influence of natural background radiation, the question of the effect of radiation on biological processes, particularly on aging processes, remains highly relevant. The parallel relationship between natural and radiation-induced cellular senescence reveals the common aspects underlying these processes. Based on recent scientific data, the key points of the effects of ionizing radiation on cellular processes associated with aging, such as genome instability, mitochondrial dysfunction, altered expression of miRNAs, epigenetic profile, and manifestation of the senescence-associated secretory phenotype (SASP), are discussed. Unraveling the molecular mechanisms of cellular senescence can make a valuable contribution to the understanding of the molecular genetic basis of age-associated diseases in the context of environmental exposure.

Molecular and Cellular Mechanism of Action of Chrysotile Asbestos in MRC5 Cell Line

Asbestos is a known carcinogen; however, the influence of chrysotile asbestos on the development of tumor-related diseases remains a subject of intense debate within the scientific community. To analyze the effect of asbestos, we conducted a study using the MRC5 cell line. We were able to demonstrate that chrysotile asbestos stimulated the production of reactive oxygen species (ROS), leading to cell death and DNA damage in the MRC5 cell line, using various techniques such as ROS measurement, comet assay, MTT assay, and qPCR. In addition, we found that chrysotile asbestos treatment significantly increased extracellular mitochondrial DNA levels in the culture medium and induced significant changes in the expression profile of several miRNAs, which was the first of its kind. Thus, our research highlights the importance of studying the effects of chrysotile asbestos on human health and reveals multiple adverse effects of chrysotile asbestos.

The mtDNA fragments within exosomes might be novel diagnostic biomarkers of non-small cell lung cancer

BACKGROUND

A portion of circulating mtDNAs is encapsulated in exosomes, but their contribution to cancers is rarely studied. We aim to investigate the diagnostic potential of exosomal mtDNA content for non-small cell lung cancer (NSCLC).

METHODS

Exosomes were isolated from plasma and identified by western blot, scanning electron microscopy, and particle size analysis. The plasma and plasma exosomal mtDNA fragment levels (mtDNA79, mtDNA230, and MTATP8) in healthy, pneumonia, benign lung tumors, and NSCLC were quantified by qPCR. Statistical analyses were performed to compare the levels of mtDNA fragments in different subgroups. ROC analyses were used to evaluate mtDNA fragments' diagnostic sensitivity and specificity.

RESULTS

We found that plasma mtDNAs were partially present in exosomes. Both plasma and exosomal mtDNA fragments (mtDNA79, mtDNA230, and MTATP8) were increased in NSCLC, particularly more malignant NSCLC. Compared to plasma mtDNAs and traditional tumor markers, exosomal mtDNAs are more closely associated with aggressive features of NSCLC, like bigger tumor sizes, advanced stages, lymph node metastasis, and distant metastasis, showing higher sensitivity and specificity to diagnose NSCLC.

CONCLUSIONS

Changed contents of plasma and plasma exosomal mtDNAs show great potential to diagnose NSCLC, and exosomal mtDNAs might be promising biomarkers for more aggressive NSCLC.

Mitochondrial DNA Copy Number: Linking Diabetes and Cancer

Recent Advances: Various studies have suggested that mitochondrial DNA copy number (mtDNA-CN), a surrogate biomarker of mitochondrial dysfunction, is an easily quantifiable biomarker for chronic diseases, including diabetes and cancer. However, current knowledge is limited, and the results are controversial. This has been attributed mainly to methodology and study design. Critical Issues: The incidence of diabetes and cancer has increased significantly in recent years. Moreover, type 2 diabetes (T2D) has been shown to be a risk factor for cancer. mtDNA-CN has been associated with both T2D and cancer. However, it is not known whether mtDNA-CN plays any role in the association between T2D and cancer. Significance: In this review, we have discussed mtDNA-CN in diabetes and cancer, and reviewed the literature and methodology used in published studies so far. Based on the literature review, we have speculated how mtDNA-CN may act as a link between diabetes and cancer. Furthermore, we have provided some recommendations for reliable translation of mtDNA-CN as a biomarker. Future Directions: Further research is required to elucidate the role of mtDNA-CN in the association between T2D and cancer. If established, early lifestyle interventions, such as physical activity and diet control that improve mitochondrial function, may help preventing cancer in patients with T2D. Antioxid. Redox Signal. 37, 1168-1190.

The Role of Mitochondrial miRNAs in the Development of Radon-Induced Lung Cancer

MicroRNAs are short, non-coding RNA molecules regulating gene expression by inhibiting the translation of messenger RNA (mRNA) or leading to degradation. The miRNAs are encoded in the nuclear genome and exported to the cytosol. However, miRNAs have been found in mitochondria and are probably derived from mitochondrial DNA. These miRNAs are able to directly regulate mitochondrial genes and mitochondrial activity. Mitochondrial dysfunction is the cause of many diseases, including cancer. In this review, we consider the role of mitochondrial miRNAs in the pathogenesis of lung cancer with particular reference to radon exposure.