circCCDC66 promotes thyroid cancer cell proliferation, migratory and invasive abilities and glycolysis through the miR-211-5p/PDK4 axis

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.

Astragaloside IV restrains pulmonary fibrosis progression via the circ_0008898/miR-211-5p/HMGB1 axis

Pulmonary Fibrosis (PF) is a fatal lung disease with complicated pathogenesis. Astragaloside IV (ASV) has been discovered to alleviate PF progression, and the potential molecular mechanism of ASV in the development of PF need to be further clarified. Bleomycin (BLM) was used to construct PF in vivo model. Expression levels of circ_0008898, miR-211-5p, high mobility group protein B1 (HMGB1), alpha smooth muscle Actin (α-SMA) and Collagen I were examined by Quantitative real time polymerase chain reaction (qRT-PCR) and western blot. Cell survival was analyzed using Cell Counting Kit-8 (CCK-8) and EdU (5-ethynyl-2'-deoxyuridine) assay. The invasion abilities were investigated by transwell assay. The levels of inflammatory factors were tested via using Enzyme-linked immunosorbent assay (ELISA). The relationship between circ_0008898 or HMGB1 and miR-211-5p was identified by dual-luciferase reporter assay. The results showed that ASV attenuated BLM-induced pulmonary fibrosis in vivo. In vitro study, ASV alleviated TGF-β1-induced fibrogenesis in HFL1 cells. Circ_0008898 was increased in TGF-β1-induced HFL1 cells. ASV-induced impacts were abrogated by circ_0008898 overexpression in TGF-β1-induced HFL1 cells. Mechanistically, circ_0008898 competitively bound to miR-211-5p to increase the expression of its target HMGB1. MiR-211-5p deficiency rescued ASV-mediated effects in TGF-β1-induced HFL1 cells. In addition, HMGB1 overexpression partially overturned circ_0008898 interference-induced impacts in HFL1 cells upon TGF-β1 treatment. In conclusion, our work manifested that ASV hindered PF process by mediating the circ_0008898/miR-211-5p/HMGB1 network.

Serum exosomal circCCDC66 as a potential diagnostic and prognostic biomarker for pituitary adenomas

Purpose

Circular RNAs (circRNAs) play an important role in tumorigenesis, and exosomal circRNAs have the potential to be novel biomarkers for cancer diagnosis. Here, we are committed to reveal serum exosomal circCCDC66 as a noninvasive biomarker to diagnose and predict recurrence in pituitary adenoma (PA).

Methods

A total of 90 PA patients and 50 healthy subjects were enrolled for clinical validation. Exosomes were extracted from the serum and validated by transmission electron microscopy, nanoparticle tracking analysis, and Western blot assay. The expression of circCCDC66 in serum exosomes was assessed using quantitative real-time PCR (qRT-PCR), and correlations between circCCDC66 expression and clinicopathological factors were analyzed. The reliability of serum exosomal circCCDC66 to diagnose PA was evaluated using receiver operating characteristic (ROC) analysis.

Results

Initially, an obviously significantly increasing level of serum exosomal circCCDC66 was verified in the PA specimens compared with healthy controls. Importantly, serum exosomal circCCDC66, which was secreted and released by PA cells, could monitor tumor dynamics and serve as a potentially prognostic biomarker during treatment. Additionally, ROC curve analysis was performed and the corresponding area under the curve (AUC) values were used to confirm the ability of serum exosomal circCCDC66 as a potentially diagnostic and prognostic biomarker for PA patients. Importantly, the progression-free survival was much longer in the low serum exosomal circCCDC66 group than in the high serum exosomal circCCDC66 group.

Conclusion

Serum exosomal circCCDC66 is abnormally elevated and may serve as a promising factor for the diagnosis of and predicting prognosis in PA patients.

CircCCDC66: Emerging roles and potential clinical values in malignant tumors

Circular RNAs (circRNAs) are endogenous non-coding RNAs (ncRNAs) with a closed-loop structure. In recent years, circRNAs have become the focus of much research into RNA. CircCCDC66 has been identified as a novel oncogenic circRNA and is up-regulated in a variety of malignant tumors including thyroid cancer, non-small cell carcinoma, gastric cancer, colorectal cancer, renal cancer, cervical cancer, glioma, and osteosarcoma. It mediates cancer progression by regulating epigenetic modifications, variable splicing, transcription, and protein translation. The oncogenicity of circCCDC66 suppresses or promotes the expression of related genes mainly through direct or indirect pathways. This finding suggests that circCCDC66 is a biomarker for cancer diagnosis, prognosis assessment and treatment. However, there is no review on the relationship between circCCDC66 and cancers. Thus, the expression, biological functions, and regulatory mechanisms of circCCDC66 in malignant tumor and non-tumor diseases are summarized. The clinical value and prognostic significance of circCCDC66 are also evaluated, which can provide insights helpful to those exploring new strategies for the early diagnosis and targeted treatment of malignancies.

MiR-211 plays a dual role in cancer development: From tumor suppressor to tumor enhancer

Cancer is a general term for more than 100 unique malignancies in different organs of the body. Each cancer type and subtype has its own unique genetic, epigenetic, and cellular factors accountable for malignant progression and metastasis. Small non-coding RNAs called miRNAs target mRNAs and play a vital part in the pathogenesis of human diseases, specifically cancer. Recent investigations provided knowledge of the deregulation of miR-211 in various cancer types and disclosed that miR-211 has an oncogenic or tumor-suppressive impact on tumourigenesis and cancer development. Moreover, recent discoveries which clarify the essential functions of miR-211 might provide proof for its prognosis, diagnostic and therapeutic impact on cancer. Thereby, this review will discuss recent findings regarding miR-211 expression level, target genes, and mechanisms in different cancers. In addition, the most recent results that propose miR-211 usefulness as a noninvasive biomarker and therapeutic factor for the diagnosis and treatment of cancer will be explained.

Research progress of circRNA in malignant tumour metabolic reprogramming

Cancer is a multi-factor systemic malignant disease, which has seriously threatened human health and created a heavy burden on the world economy. Metabolic reprogramming, one of the important signs of malignant tumours, provides necessary nutrition for tumorigenesis and cancer development; thus, it has recently become a research hot spot, even though the metabolic mechanism is quite intricate. Circular RNA (circRNA) affects cancer cell metabolism through various molecular mechanisms, playing an important role in promoting or suppressing cancer. Because of the structure characteristics, circRNA is quite stable, and can be utilized as biomarkers. In this review, we analysed and summarized the characteristics and biological functions of circRNA and comprehensively reviewed and discussed the important role of circRNA in cancer metabolic reprogramming. This review will provide new ideas for developing new anti-cancer therapeutic targets, mining cancer diagnostic and prognostic markers, and will provide guidance for other researchers to design circRNA-related experiments and develop anti-tumour drugs.

Function and Clinical Significance of Circular RNAs in Thyroid Cancer

Thyroid cancer (TC) is the leading cause and mortality of endocrine malignancies worldwide. Tumourigenesis involves multiple molecules including circular RNAs (circRNAs). circRNAs with covalently closed single-stranded structures have been identified as a type of regulatory RNA because of their high stability, abundance, and tissue/developmental stage-specific expression. Accumulating evidence has demonstrated that various circRNAs are aberrantly expressed in thyroid tissues, cells, exosomes, and body fluids in patients with TC. CircRNAs have been identified as either oncogenic or tumour suppressor roles in regulating tumourigenesis, tumour metabolism, metastasis, ferroptosis, and chemoradiation resistance in TC. Importantly, circRNAs exert pivotal effects on TC through various mechanisms, including acting as miRNA sponges or decoys, interacting with RNA-binding proteins, and translating functional peptides. Recent studies have suggested that many different circRNAs are associated with certain clinicopathological features, implying that the altered expression of circRNAs may be characteristic of TC. The purpose of this review is to provide an overview of recent advances on the dysregulation, functions, molecular mechanisms and potential clinical applications of circRNAs in TC. This review also aimes to improve our understanding of the functions of circRNAs in the initiation and progression of cancer, and to discuss the future perspectives on strategies targeting circRNAs in TC.

The Epithelial-Mesenchymal Transition at the Crossroads between Metabolism and Tumor Progression

The transition between epithelial and mesenchymal phenotype is emerging as a key determinant of tumor cell invasion and metastasis. It is a plastic process in which epithelial cells first acquire the ability to invade the extracellular matrix and migrate into the bloodstream via transdifferentiation into mesenchymal cells, a phenomenon known as epithelial–mesenchymal transition (EMT), and then reacquire the epithelial phenotype, the reverse process called mesenchymal–epithelial transition (MET), to colonize a new organ. During all metastatic stages, metabolic changes, which give cancer cells the ability to adapt to increased energy demand and to withstand a hostile new environment, are also important determinants of successful cancer progression. In this review, we describe the complex interaction between EMT and metabolism during tumor progression. First, we outline the main connections between the two processes, with particular emphasis on the role of cancer stem cells and LncRNAs. Then, we focus on some specific cancers, such as breast, lung, and thyroid cancer.

CircTP63 promotes cell proliferation and invasion by regulating EZH2 via sponging miR-217 in gallbladder cancer

Background

Gallbladder cancer (GBC) is the most common biliary tract malignancy and has a poor prognosis in patients with GBC. CircRNA TP63 (circTP63) has been implicated in cell proliferation and invasion in some tumor progress. The study aims to investigate the clinical significance and functional role of circTP63 expression in GBC.

Methods

The expression of circTP63 in GBC tissues or cells was detected by qRT-PCR and the association between circTP63 expression and prognosis of GBC patients was analyzed. CCK8 assay, flow cytometry analysis, transwell assay and in vivo studies were used to evaluate the cell proliferation and invasion abilities after circTP63 knockdown in GBC cells. Luciferase reporter assays and RNA pull-down assay were used to determine the correlation between circTP63 and miR-217 expression. Besides, western blot analysis was also performed.

Results

In the present study, we showed that circTP63 expression was upregulated in GBC tissues and cells. Higher circTP63 expression was associated with lymph node metastasis and short overall survival (OS) in patients with GBC. In vitro, knockdown of circTP63 significantly inhibited cell proliferation, cell cycle progression, migration and invasion abilities in GBC. Besides, we demonstrated that knockdown of circTP63 inhibited GBC cells Epithelial-Mesenchymal Transition (EMT) process. In vivo, knockdown of circTP63 inhibited tumor growth in GBC. Mechanistically, we demonstrated that circTP63 competitively bind to miR-217 and promoted EZH2 expression and finally facilitated tumor progression.

Conclusions

Our findings demonstrated that circTP63 sponged to miR-217 and regulated EZH2 expression and finally facilitated tumor progression in GBC. Thus, targeting circTP63 may be a therapeutic strategy for the treatment of GBC.

Metabolic Reprogramming in Thyroid Cancer: Role of the Epithelial-Mesenchymal Transition

Thyroid cancer (TC) represents the most common endocrine malignancy, with an increasing incidence all over the world. Papillary TC (PTC), a differentiated TC subtype, is the most common and, even though it has an excellent prognosis following radioiodine (RAI) ablation, it shows an aggressive behavior in 20–30% of cases, becoming RAI-resistant and/or metastatic. On the other side, anaplastic thyroid carcinoma (ATC), the most undifferentiated TC, is a rare but devastating disease, indicating that progression of differentiated to undifferentiated forms of TC could be responsible for RAI-resistance and increased mortality. The epithelial-to-mesenchymal transition (EMT) plays a pivotal role in both tumor progression and resistance to therapy. Moreover, during tumor progression, cancer cells modify their metabolism to meet changed requirements for cellular proliferation. Through these metabolic changes, cancer cells may adopt cancer stem cell-like properties and express an EMT phenotype. EMT, in turn, can induce metabolic changes to which cancer cells become addicted. Here we review metabolic reprogramming in TC highlighting the role of EMT with the aim to explore a potential field to find out new therapeutic strategies for advanced-stage PTC. Accordingly, we discuss the identification of the metabolic enzymes and metabolites, critical to TC progression, which can be employed either as predicting biomarkers of tumor response to RAI therapy or possible targets in precision medicine.

CircRNA: A novel potential strategy to treat thyroid cancer (Review)

Thyroid cancer (TC) is the most common type of endocrine cancer. Over the last 50 years, the global incidence of TC has been increasing. The survival rate of TC is higher than that of most other types of cancer, but it depends on numerous factors, including the specific type of TC and stage of the disease. Circular RNAs (circRNAs) are a new class of long noncoding RNA with a closed loop structure that have a critical role in the complex gene regulatory network that controls the emergence of TC. The most important function of circRNAs is their ability to specifically bind to microRNAs. In addition, the biological functions of circRNAs also include interactions with proteins, regulation of the transcription of genes and acting as translation templates. Based on the characteristics of circRNAs, they have been identified as potential biomarkers for the diagnosis of tumors. In the present review, the function and significance of circRNAs and their potential clinical implications for TC were summarized. Furthermore, possible treatment approaches involving the use of mesenchymal stem cells (MSCs) and exosomes derived from MSCs as carriers to load and transport circRNAs were discussed.

Circular RNAs Regulate Glucose Metabolism in Cancer Cells

Circular RNAs (circRNAs) were originally thought to result from RNA splicing errors. However, it has been shown that circRNAs can regulate cancer onset and progression in various ways. They can regulate cancer cell proliferation, differentiation, invasion, and metastasis. Moreover, they modulate glucose metabolism in cancer cells through different mechanisms such as directly regulating glycolytic enzymes and glucose transporter (GLUT) or indirectly regulating signal transduction pathways. In this review, we elucidate on the role of circRNAs in regulating glucose metabolism in cancer cells, which partly explains the pathogenesis of malignant tumors, and provides new therapeutic targets or new diagnostic and prognostic markers for human cancers.