Circ_0027446 induces CLDN1 expression to promote papillary thyroid cancer cell malignancy by binding to miR-129-5p

Emerging roles of circular RNAs in regulating the hallmarks of thyroid cancer

Thyroid cancer is a prevalent endocrine malignancy with increasing incidence in recent years. Although most thyroid cancers grow slowly, they can become refractory, leading to a high mortality rate once they exhibit recurrence, metastasis, resistance to radioiodine therapy, or a lack of differentiation. However, the mechanisms underlying these malignant characteristics remain unclear. Circular RNAs, a type of closed-loop non-coding RNAs, play multiple roles in cancer. Several studies have demonstrated that circular RNAs significantly influence the development of thyroid cancers. In this review, we summarize the circular RNAs identified in thyroid cancers over the past decade according to the hallmarks of cancer. We found that eight of the 14 hallmarks of thyroid cancers are regulated by circular RNAs, whereas the other six have not been reported to be correlated with circular RNAs. This review is expected to help us better understand the roles of circular RNAs in thyroid cancers and accelerate research on the mechanisms and cure strategies for thyroid cancers.

Circ_0027446 promotes malignant development of glioblastoma by interacting with miR-346 to up-regulate PGK1

Circular RNAs (circRNAs) can play essential roles in tumor development, including glioblastoma (GBM). The current study was performed to explore the function and mechanism of circ_0027446 in GBM progression. Circ_0027446, microRNA-346 (miR-346) and Phosphoglycerate kinase 1 (PGK1) levels were detected using reverse transcription-quantitative polymerase chain reaction assay. Cell behaviors were examined using Cell Counting Kit-8 assay, colony formation assay, EdU assay, flow cytometry, and transwell assay. Glycolytic metabolism was analyzed by commercial kits. The protein level was determined via western blot. The target interaction was analyzed by dual-luciferase reporter assay. Circ_0027446 function in vivo was explored by tumor xenograft assay. Circ_0027446 expression was significantly up-regulated in GBM samples and cells. Circ_0027446 down-regulation suppressed proliferation, invasion, glycolytic metabolism and enhanced apoptosis of GBM cells. MiR-346 was a target of circ_0027446, and circ_0027446 promoted GBM progression by sponging miR-346. PGK1 acted as a target gene of miR-346, and circ_0027446 interacted with miR-346 to regulate PGK1 expression. Overexpression of miR-346 inhibited malignant behaviors of GBM cells through down-regulating PGK1. Circ_0027446 contributed to tumor growth in vivo via miR-346/PGK1 axis. The current evidences demonstrated that circ_0027446 facilitated malignant progression of GBM through binding to miR-346 to up-regulate PGK1.

Effect and mechanism of circHMGA2 on ferroptosis and pyroptosis in myocardial ischemia-reperfusion model CircHMGA2 exacerbates MI/R injury

Myocardial ischemia-reperfusion (MI/R) injury is a common and serious complication following reperfusion treatment for myocardial infarction (MI). Increasing evidence has verified the crucial role of circular RNAs (circRNAs) in the MI/R injury processes. The objective of this study was to investigate the effects and potential regulatory mechanisms of circHMGA2 on MI/R injury. Hypoxia/reoxygenation (H/R) models were established using human cardiac myocytes (HCMs) and mice models were induced by MI/R. The level of circHMGA2 was detected by RT-qPCR. Myocardial function was evaluated by the hemodynamic parameters, the activity of serum myocardial enzymes, HE staining and TUNEL assays. Cell proliferation was measured by CCK-8 assay. The ferrous ion (Fe²⁺) level was determined with an iron assay kit. Ferroptosis- and pyroptosis-related proteins were determined using western blotting. The levels of oxidative stress and inflammatory factors were analyzed using DCFH-DA staining or ELISA assays. CircHMGA2 was upregulated in H/R-induced HCMs and myocardial tissues of MI/R mice. In vitro, circHMGA2 knockdown attenuated the proliferation inhibition, restrained the ferroptosis and pyroptosis in H/R-induced HCMs. This regulatory mechanism may be associated with the suppression of NLRP3 pathway. In vivo, circHMGA2 depletion attenuated myocardial tissue damage of MI/R mice through inhibiting the oxidative stress and pyroptosis. Taken together, CircHMGA2 enhanced MI/R injury via promoting ferroptosis and pyroptosis, providing new insights into the treatment of MI/R injury.