The characteristics of extrachromosomal circular DNA in patients with end-stage renal disease

Exploring the Role of Clustered Mutations in Carcinogenesis and Their Potential Clinical Implications in Cancer

Abnormal cell proliferation and growth leading to cancer primarily result from cumulative genome mutations. Single gene mutations alone do not fully explain cancer onset and progression; instead, clustered mutations-simultaneous occurrences of multiple mutations-are considered to be pivotal in cancer development and advancement. These mutations can affect different genes and pathways, resulting in cells undergoing malignant transformation with multiple functional abnormalities. Clustered mutations influence cancer growth rates, metastatic potential, and drug treatment sensitivity. This summary highlights the various types and characteristics of clustered mutations to understand their associations with carcinogenesis and discusses their potential clinical significance in cancer. As a unique mutation type, clustered mutations may involve genomic instability, DNA repair mechanism defects, and environmental exposures, potentially correlating with responsiveness to immunotherapy. Understanding the characteristics and underlying processes of clustered mutations enhances our comprehension of carcinogenesis and cancer progression, providing new diagnostic and therapeutic approaches for cancer.

Identification and characterization of extrachromosomal circular DNA in large-artery atherosclerotic stroke

Extrachromosomal circular DNA (eccDNA) is a new biomarker and regulator of diseases. However, the role of eccDNAs in large-artery atherosclerotic (LAA) stroke remains unclear. Through high-throughput circle-sequencing technique, the length distribution, genomic characteristic and motifs feature of plasma eccDNA from healthy controls (CON) and patients with LAA stroke were analysed. Then, the potential functions of the annotated eccDNAs were investigated using GO and KEGG pathway analyses. EccDNAs mapped to the reference genome showed SHN3 and BCL6 were LAA stroke unique transcription factors. The genes of differentially expressed eccDNAs between LAA stroke patients and CON were mainly involved in axon/dendrite/neuron projection development and maintenance of cellular structure via Wnt, Rap1 and MAPK pathways. Moreover, LAA stroke unique eccDNA genes played a role in regulation of coagulation and fibrinolysis, and there were five LAA stroke unique eccDNAs (Chr2:12724406-12724784, Chr4:1867120-186272046, Chr4:186271494-186271696, Chr7:116560296-116560685 and Chr11:57611780-5761192). Additionally, POLR2C and AURKA carried by ecDNAs (eccDNA size >100 kb) of LAA stroke patients were significantly associated with development of LAA stroke. Our data firstly revealed the characteristics of eccDNA in LAA stroke and the functions of LAA stroke unique eccDNAs and eccDNA genes, suggesting eccDNA is a novel biomarker and mechanism of LAA stroke.

Molecular characterization and functional roles of circulating cell-free extrachromosomal circular DNA

Circular DNA segments isolated from chromosomes are known as extrachromosomal circular DNA (eccDNA). Its distinct structure and characteristics, along with the variations observed in different disease states, makes it a promising biomarker. Recent studies have revealed the presence of eccDNAs in body fluids, indicating their involvement in various biological functions. This finding opens up avenues for utilizing eccDNAs as convenient and real-time biomarkers for disease diagnosis, treatment monitoring, and prognosis assessment through noninvasive analysis of body fluids. In this comprehensive review, we focused on elucidating the size profiles, potential mechanisms of formation and clearance, detection methods, and potential clinical applications of eccDNAs. We aimed to provide a valuable reference resource for future research in this field.

Increased serum extrachromosomal circular DNA SORBS1circle level is associated with insulin resistance in patients with newly diagnosed type 2 diabetes mellitus

BACKGROUND

Extrachromosomal circular DNAs (eccDNAs) exist in human blood and somatic cells, and are essential for oncogene plasticity and drug resistance. However, the presence and impact of eccDNAs in type 2 diabetes mellitus (T2DM) remains inadequately understood.

METHODS

We purified and sequenced the serum eccDNAs obtained from newly diagnosed T2DM patients and normal control (NC) subjects using Circle-sequencing. We validated the level of a novel circulating eccDNA named sorbin and SH3-domain- containing-1circle97206791-97208025 (SORBS1circle) in 106 newly diagnosed T2DM patients. The relationship between eccDNA SORBS1circle and clinical data was analyzed. Furthermore, we explored the source and expression level of eccDNA SORBS1circle in the high glucose and palmitate (HG/PA)-induced hepatocyte (HepG2 cell) insulin resistance model.

RESULTS

A total of 22,543 and 19,195 eccDNAs were found in serum samples obtained from newly diagnosed T2DM patients and NC subjects, respectively. The T2DM patients had a greater distribution of eccDNA on chromosomes 1, 14, 16, 17, 18, 19, 20 and X. Additionally, 598 serum eccDNAs were found to be upregulated, while 856 eccDNAs were downregulated in T2DM patients compared with NC subjects. KEGG analysis demonstrated that the genes carried by eccDNAs were mainly associated with insulin resistance. Moreover, it was validated that the eccDNA SORBS1circle was significantly increased in serum of newly diagnosed T2DM patients (106 T2DM patients vs. 40 NC subjects). The serum eccDNA SORBS1circle content was positively correlated with the levels of glycosylated hemoglobin A1C (HbA1C) and homeostasis model assessment of insulin resistance (HOMA-IR) in T2DM patients. Intracellular eccDNA SORBS1circle expression was significantly enhanced in the high glucose and palmitate (HG/PA)-induced hepatocyte (HepG2 cell) insulin resistance model. Moreover, the upregulation of eccDNA SORBS1circle in the HG/PA-treated HepG2 cells was dependent on generation of apoptotic DNA fragmentation.

CONCLUSIONS

These results provide a preliminary understanding of the circulating eccDNA patterns at the early stage of T2DM and suggest that eccDNA SORBS1circle may be involved in the development of insulin resistance.

A comprehensive analysis of library preparation methods shows high heterogeneity of extrachromosomal circular DNA but distinct chromosomal amount levels reflecting different cell states

Extrachromosomal circular DNA (eccDNA) was discovered several decades ago, but little is known about its function. With the development of sequencing technology, several library preparation methods have been developed to elucidate the biogenesis and function of eccDNA. However, different treatment methods have certain biases that can lead to their erroneous interpretation. To address these issues, we compared the performance of different library preparation methods. Our investigation revealed that the utilization of rolling-circle amplification (RCA) and restriction enzyme linearization of mitochondrial DNA (mtDNA) significantly enhanced the efficiency of enriching extrachromosomal circular DNA (eccDNA). However, it also introduced certain biases, such as an unclear peak in ∼160-200 bp periodicity and the absence of a typical motif pattern. Furthermore, given that RCA can lead to a disproportionate change in copy numbers, eccDNA quantification using split and discordant reads should be avoided. Analysis of the genomic and elements distribution of the overall population of eccDNA molecules revealed a high correlation between the replicates, and provided a possible stability signature for eccDNA, which could potentially reflect different cell lines or cell states. However, we found only a few eccDNA with identical junction sites in each replicate, showing a high degree of heterogeneity of eccDNA. The emergence of different motif patterns flanking junctional sites in eccDNAs of varying sizes suggests the involvement of multiple potential mechanisms in eccDNA generation. This study comprehensively compares and discusses various essential approaches for eccDNA library preparation, offering valuable insights and practical advice to researchers involved in characterizing eccDNA.

Extrachromosomal DNA (ecDNA): Unveiling its role in cancer progression and implications for early detection

Extrachromosomal DNA (ecDNA) is a special class of circular DNA in eukaryotes, which is independent of conventional chromosomes. These circular molecules play important roles in biology, especially in cancer biology. The emergence of sequencing technologies such as CCDA-seq and Amplicon Architect has led to a progressive unraveling of the mystery of ecDNA. Consequently, insights into its function and potential applications have begun to surface. Among these studies, the most noteworthy research pertains to cancer-related investigations into ecDNA. Numerous studies have underscored the significance of ecDNA in the pathogenesis of cancer and its role in accelerating cancer evolution. This review provides an overview of the source, structure, and function of ecDNA, while compiling recent advancements in ecDNA in the field of cancer. Nonetheless, further research is imperative to determine its effectiveness and specificity as a biomarker for early cancer detection.