Background. COVID-19, the disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to a global pandemic and mortality of people around the world. Some circular RNAs (circRNAs), one of the new types of noncoding RNAs (ncRNAs), act as competing endogenous RNAs (ceRNAs) and compete with mRNAs for shared miRNAs, to regulate gene expression. In the present study, we aimed to evaluate the expression and roles of hsa_circ_0000479/hsa-miR-149-5p/RIG-I, IL-6 in COVID-19 infection. Materials and Methods. After extraction of total RNA from peripheral blood mononuclear cells (PBMC) of 50 patients with symptomatic COVID-19, 50 patients with nonsymptomatic COVID-19, and 50 normal controls, cDNA synthesis was performed. Online in silico tools were applied to evaluate the interaction between the genes in the hsa_circ_0000479/hsa-miR-149-5p/RIG-I, IL-6 axis, and its role in COVID-19-related pathways. Quantification of the expression of these genes and confirmation of their interaction was done using the quantitative real-time PCR (qRT-PCR) technique. Results. The expression levels of hsa_circ_0000479, RIG-I, and IL-6 were increased in COVID-19 patients compared to healthy controls, while hsa-miR-149-5p expression was decreased. Moreover, there was a significant negative correlation between hsa-miR-149-5p and hsa_circ_0000479, RIG-I, IL-6 expressions, and also a positive expression correlation between hsa_circ_0000479 and IL-6, RIG-I. Then, bioinformatics tools revealed the role of hsa_circ_0000479/hsa-miR-149-5p/RIG-I, IL-6 axis in PI3K-AKT and STAT3 signaling pathways. Conclusion. Upregulation of hsa_circ_0000479, RIG-I, and IL-6, and downregulation of hsa-miR-149-5p, along with correlation studies, indicate that hsa_circ_0000479/hsa-miR-149-5p/RIG-I, IL-6 axis could play a role in regulating the immune response against SARS-CoV-2. However, more studies are needed in this area.

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Background Breast cancer (BC) is one of the leading causes of death among women around the world. Circular RNAs (circRNAs) are a newly discovered group of non‐coding RNAs that their roles are being investigated in BC and other cancer types. In this study, we evaluated the association of hsa_circ_0005986 and hsa_circ_000839 in tumor and adjacent normal tissues of BC patients with their clinicopathological characteristics. Materials and methods Total RNA was extracted from tumors and adjacent non‐tumor tissues by the Trizol isolation reagent, and cDNA was synthesized using First Strand cDNA Synthesis Kit (Thermo Scientific). The expression level of hsa_circ_0005986 and hsa_circ_000839 was quantified using RT‐qPCR. Online in silico tools were used for identifying potentially important competing endogenous RNA (ceRNA) networks of these two circRNAs. Results The expression level of hsa_circ_0005986 and hsa_circ_000839 was lower in the tumor as compared to adjacent tissues. The expression level of hsa_circ_0005986 in the patients who had used hair dye in the last 5 years was significantly lower. Moreover, a statistically significant negative correlation between body mass index (BMI) and hsa_circ_000839 expression was observed. In silico analysis of the ceRNA network of these circRNAs revealed mRNAs and miRNAs with crucial roles in BC. Conclusion Downregulation of hsa_circ_000839 and hsa_circ_0005986 in BC tumors suggests a tumor‐suppressive role for these circRNAs in BC, meriting the need for more experimentations to delineate the exact mechanism of their involvement in BC pathogenesis.

Background: Circular RNAs (circRNAs), covalently closed single-stranded non-coding RNAs (ncRNAs), play pivotal roles in development and progression of breast cancer (BC). Although the roles of hsa_circ_0013958 and hsa_circ_0003028 in some malignancies have been explored, their function and expression in breast tumors are still unknown. This study was aimed to bioinformatically and experimentally evaluates the expression and potential function of hsa_circ_0013958 and hsa_circ_0003028 in BC. Materials and Methods: The quantitative real-time PCR method was used to determine the expression of hsa_circ_0013958 and hsa_circ_0003028 in 50 tumor samples and matched adjacent non-cancerous tissues. Besides, we used bioinformatic approaches to identify potentially important competing endogenous RNA (ceRNA) networks that are regulated by these circRNAs using some databases and software tools. Results: The hsa_circ_0013958 was significantly down-regulated in breast tumors compared with adjacent normal tissues, while the hsa_circ_0003028 had an upregulated pattern. Interestingly, it is found the higher expression of hsa_circ_0013958 showed association with a lack of use of hair dye as well as age at menarche ≥14 years in subjects. On the other hand, hsa_circ_0003028 expression was meaningfully related to age at first full-term pregnancy, antiperspirants use, and regular menstruation. Next, we found that these two circRNAs can potentially regulate some circRNAs-mediated miRNA sponge regulatory networks. Conclusion: The current work indicated that the hsa_circ_0013958 and hsa_circ_0003028 had reverse expression patterns in breast tumors, and it seems that they play key roles in the physiopathology of this cancer through potential key regulatory ceRNA functions. However, further functional studies are needed to validate these bioinformatically observed roles. [GMJ.2021;10:e2064]

Background SARS‐CoV‐2 is one of the most contagious viruses in the Coronaviridae (CoV) family, which has become a pandemic. The aim of this study is to understand more about the role of hsa_circ_0004812 in the SARS‐CoV‐2 related cytokine storm and its associated molecular mechanisms. Materials and Methods cDNA synthesis was performed after total RNA was extracted from the peripheral blood mononuclear cells (PBMC) of 46 patients with symptomatic COVID‐19, 46 patients with asymptomatic COVID‐19, and 46 healthy controls. The expression levels of hsa_circ_0004812, hsa‐miR‐1287‐5p, IL6R, and RIG‐I were determined using qRT‐PCR, and the potential interaction between these molecules was confirmed by bioinformatics tools and correlation analysis. Results hsa_circ_0004812, IL6R, and RIG‐I are expressed higher in the severe symptom group compared with the negative control group. Also, the relative expression of these genes in the asymptomatic group is lower than in the severe symptom group. The expression level of hsa‐miR‐1287‐5p was positively correlated with symptoms in patients. The results of the bioinformatics analysis predicted the sponging effect of hsa_circ_0004812 as a competing endogenous RNA on hsa‐miR‐1287‐5p. Moreover, there was a significant positive correlation between hsa_circ_0004812, RIG‐I, and IL‐6R expressions, and also a negative expression correlation between hsa_circ_0004812 and hsa‐miR‐1287‐5p and between hsa‐miR‐1287‐5p, RIG‐I, and IL‐6R. Conclusion The results of this in‐vitro and in silico study show that hsa_circ_0004812/hsa‐miR‐1287‐5p/IL6R, RIG‐I can play an important role in the outcome of COVID‐19.