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. 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. 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. 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.

中文翻译：

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新诊断2型糖尿病患者血清染色体外环状DNA SORBS1circle水平升高与胰岛素抵抗相关

染色体外环状 DNA (eccDNA) 存在于人类血液和体细胞中，对于癌基因的可塑性和耐药性至关重要。然而，eccDNA 在 2 型糖尿病 (T2DM) 中的存在和影响仍不清楚。我们使用环形测序对从新诊断的 T2DM 患者和正常对照 (NC) 受试者获得的血清 eccDNA 进行纯化和测序。我们在 106 名新诊断的 T2DM 患者中验证了一种名为 sorbin 和 SH3 结构域的新型循环 eccDNA 的水平，该 eccDNA 包含 1circle97206791-97208025 (SORBS1circle)。分析eccDNA SORBS1circle与临床数据的关系。此外，我们还探讨了eccDNA SORBS1circle在高糖和棕榈酸酯（HG/PA）诱导的肝细胞（HepG2细胞）胰岛素抵抗模型中的来源和表达水平。在新诊断的 T2DM 患者和 NC 受试者的血清样本中分别发现了 22,543 个和 19,195 个 eccDNA。T2DM 患者的 eccDNA 在 1、14、16、17、18、19、20 和 X 号染色体上分布较多。此外，与 NC 受试者相比，T2DM 患者中有 598 个血清 eccDNA 上调，而 856 个 eccDNA 下调。KEGG分析表明eccDNA携带的基因主要与胰岛素抵抗相关。此外，还验证了新诊断的 T2DM 患者血清中的 eccDNA SORBS1circle 显着增加（106 名 T2DM 患者与 40 名 NC 受试者）。T2DM患者血清eccDNA SORBS1circle含量与糖化血红蛋白A1C（HbA1C）水平和胰岛素抵抗稳态模型评估（HOMA-IR）呈正相关。在高糖和棕榈酸酯（HG/PA）诱导的肝细胞（HepG2细胞）胰岛素抵抗模型中，细胞内eccDNA SORBS1circle表达显着增强。此外，HG/PA处理的HepG2细胞中eccDNA SORBS1circle的上调依赖于凋亡DNA片段的产生。这些结果提供了对T2DM早期循环eccDNA模式的初步了解，并表明eccDNA SORBS1circle可能参与胰岛素抵抗的发展。