Circular RNAs (circRNAs) are an abundant class of endogenous non‑coding RNAs and are associated with numerous diseases, including cancer, cardiovascular diseases, and type 2 diabetes mellitus (T2DM). However, the association between circRNAs and inflammation or inflammatory cytokines in patients with T2DM remains to be fully elucidated. The purpose of the present study was to investigate the expression profiles of circRNAs in peripheral leucocytes of patients with T2DM and their association with inflammatory cytokines. Peripheral blood from patients with T2DM (n=43) and healthy individuals (n=45) were collected for RNA sequencing and later verification. Reverse transcription‑polymerase chain reaction (RT‑PCR) and reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analyses were used to detect the expression levels of circRNAs. The expression of inflammatory factors, including interleukin (IL)‑1, (IL)‑6, and tumor necrosis factor (TNF)‑α were measured via enzyme‑linked immunosorbent assay. Furthermore, the mRNA expression level of ankyrin repeat domain 36 (ANKRD36), a protein located at 2q11.2 that interacts with the GAPDH gene, was measured using RT‑qPCR analysis. The circRNA/microRNA (miRNA) interaction was predicted using RegRNA and mirPath software. In total, 220 circRNAs were found to be differentially expressed between patients with T2DM and healthy individuals, of which 107 were upregulated and 113 were downregulated. Among the nine selected circRNAs, circANKRD36 was significantly upregulated in patients with T2DM compared with control subjects (P=0.02). The expression level of circANKRD36 was positively correlated with glucose and glycosylated hemoglobin (r=0.3250, P=0.0047 and r=0.3171, P=0.0056, respectively). The expression level of IL‑6 was significantly different between the T2DM group and control group (P=0.028) and was positively correlated with circANKRD36. The difference of circANKRD36 host gene expression between patients with T2DM and healthy controls was significant (P=0.04). Taken together, circANKRD36 may be involved in T2DM and inflammation‑associated pathways via interaction with miRNAs, including hsa‑miR‑3614‑3p, hsa‑miR‑498, and hsa‑miR‑501‑5p. The expression of circANKRD36 was up­regulated in peripheral blood leucocytes and was correlated with chronic inflammation in T2DM. Therefore, circANKRD36 can be used as a potential biomarker for screening chronic inflammation in patients with T2DM.

Classic strategies for circular RNA (circRNA) preparation always introduce large numbers of linear transcripts or extra nucleotides to the circularized product. In this study, we aimed to develop an efficient system for circRNA preparation based on a self-splicing ribozyme derived from an optimized Tetrahymena thermophila group Ⅰ intron. The target RNA sequence was inserted downstream of the ribozyme and a complementary antisense region was added upstream of the ribozyme to assist cyclization. Then, we compared the circularization efficiency of ribozyme or flanking intronic complementary sequence (ICS)-mediated methods through the DNMT1, CDR1as, FOXO3, and HIPK3 genes and found that the efficiency of our system was remarkably higher than that of flanking ICS-mediated method. Consequently, the circularized products mediated by ribozyme are not introduced with additional nucleotides. Meanwhile, the overexpressed circFOXO3 maintained its biological functions in regulating cell proliferation, migration, and apoptosis. Finally, a ribozyme-based circular mRNA expression system was demonstrated with a split green fluorescent protein (GFP) using an optimized Coxsackievirus B3 (CVB3) internal ribosome entry site (IRES) sequence, and this system achieved successful translation of circularized mRNA. Therefore, this novel, convenient, and rapid engineering RNA circularization system can be applied for the functional study and large-scale preparation of circular RNA in the future.

Background: Small extrachromosomal circular DNAs (eccDNAs) have the potential to be cancer biomarkers. However, the formation mechanisms and functions of small eccDNAs selected in carcinogenesis are not clear, and whether the small eccDNA profile in the plasma of cancer patients represents that in cancer tissues remains to be elucidated.Methods: A novel sequencing workflow based on the nanopore sequencing platform was used to sequence naturally existing full‐length small eccDNAs in tissues and plasma collected from 25 cancer patients (including prostate cancer, hepatocellular carcinoma and colorectal cancer), and from an independent validation cohort (including 7 cancer plasma and 14 healthy plasma).Results: Compared with those in non‐cancer tissues, small eccDNAs detected in cancer tissues had a significantly larger number and size (P = 0.040 and 2.2e‐16, respectively), along with more even distribution and different formation mechanisms. Although small eccDNAs had different general characteristics and genomic annotation between cancer tissues and the paired plasma, they had similar formation mechanisms and cancer‐related functions. Small eccDNAs originated from some specific genes had great multi‐cancer diagnostic value in tissues (AUC ≥ 0.8) and plasma (AUC > 0.9), especially increasing the accuracy of multi‐cancer prediction of CEA/CA19‐9 levels. The high multi‐cancer diagnostic value of small eccDNAs originated from ALK&ETV6 could be extrapolated from tissues (AUC = 0.804) to plasma and showed high positive predictive value (100%) and negative predictive value (82.35%) in a validation cohort.Conclusions: As independent and stable circular DNA molecules, small eccDNAs in both tissues and plasma can be used as ideal biomarkers for cost‐effective multi‐cancer diagnosis and monitoring.

The heart is a muscular organ that pumps blood throughout the body and is one of the most vital organs in human body. While cardiomyocytes are essential for maintaining the normal function of the heart, a variety of cardiovascular diseases such as coronary artery occlusion, arrhythmia, and myocarditis can lead to cardiomyocyte death, resulting in deterioration of heart function. The adult mammalian heart is incapable of regenerating sufficient cardiomyocytes following cardiac injuries, eventually leading to heart failure and death. Cardiac macrophages are ubiquitously distributed in the healthy heart and accumulated at the site of injury. Macrophages play essential roles in regulating homeostasis and proliferation of cardiomyocyte, promoting electrical conduction, and removing dead cardiomyocytes and debris through direct and indirect cell–cell crosstalk. In this review, we summarize the latest insights into the role of macrophages in maintaining cardiac homeostasis and the macrophage-cardiomyocyte crosstalk in both healthy and injured scenarios.

Circular RNAs (circRNAs) are a class of single‐stranded closed RNAs that are produced by the back splicing of precursor mRNAs. The formation of circRNAs mainly involves intron‐pairing‐driven circularization, RNA‐binding protein (RBP)‐driven circularization, and lariat‐driven circularization. The vast majority of circRNAs are found in the cytoplasm, and some intron‐containing circRNAs are localized in the nucleus. CircRNAs have been found to function as microRNA (miRNA) sponges, interact with RBPs and translate proteins, and play an important regulatory role in the development and progression of cancer. CircRNAs exhibit tissue‐ and developmental stage–specific expression and are stable, with longer half‐lives than linear RNAs. CircRNAs have great potential as biomarkers for cancer diagnosis and prognosis, which is highlighted by their detectability in tissues, especially in fluid biopsy samples such as plasma, saliva, and urine. Here, we review the current studies on the properties and functions of circRNAs and their clinical application value.

Background: Abiraterone and MDV3100 are two effective anticancer agents for prostate cancer, however, the mechanism of their downstream action remains undefined.Methods: A dual fluorescent biosensor plasmid was transfected in LNCaP cells to measure mitophagy. The DNA of LNCaP cells was extracted and performed with quantitative real-time PCR to detect mitochondrial DNA copy number. JC-1 staining was utilized to detect the mitochondrial membrane potential and electron microscope was performed to analyze mitochondrial morphology. Moreover, the protein levels of mitochondrial markers and apoptotic markers were detected by western blot. At last, the proliferation and apoptosis of LNCaP cells were analyzed with CCK-8 assay and flow cytometry after abiraterone or MDV3100 treatment.Results: Mitophagy was induced by abiraterone and MDV3100 in LNCaP cells. The low expression level of mitochondrial DNA copy number and mitochondrial depolarization were further identified in the abiraterone or MDV3100 treatment groups compared with the control group. Besides, severe mitochondria swelling and substantial autophagy-lysosomes were observed in abiraterone- and MDV3100-treated LNCaP cells. The expression of mitochondria-related proteins, frataxin, ACO2 and Tom20 were significantly downregulated in abiraterone and MDV3100 treated LNCaP cells, whereas the expression level of inner membrane protein of mitochondria (Tim23) was significantly upregulated in the same condition. Moreover, the proliferation of LNCaP cells were drastically inhibited, and the apoptosis of LNCaP cells was increased in abiraterone or MDV3100 treatment groups. Meanwhile, the addition of mitophagy inhibitor Mdivi-1 (mitochondrial division inhibitor 1) could conversely elevate proliferation and constrain apoptosis of LNCaP cells.Conclusions: Our results prove that both abiraterone and MDV3100 inhibit the proliferation, promote the apoptosis of prostate cancer cells through regulating mitophagy. The promotion of mitophagy might enhance the efficacy of abiraterone and MDV3100, which could be a potential strategy to improve chemotherapy with these two reagents.