Circular RNA circ_0062389 modulates papillary thyroid carcinoma progression via the miR-1179/high mobility group box 1 axis

Circular RNAs in cancer

Circular RNA (circRNA), a subtype of noncoding RNA, has emerged as a significant focus in RNA research due to its distinctive covalently closed loop structure. CircRNAs play pivotal roles in diverse physiological and pathological processes, functioning through mechanisms such as miRNAs or proteins sponging, regulation of splicing and gene expression, and serving as translation templates, particularly in the context of various cancers. The hallmarks of cancer comprise functional capabilities acquired during carcinogenesis and tumor progression, providing a conceptual framework that elucidates the nature of the malignant transformation. Although numerous studies have elucidated the role of circRNAs in the hallmarks of cancers, their functions in the development of chemoradiotherapy resistance remain unexplored and the clinical applications of circRNA-based translational therapeutics are still in their infancy. This review provides a comprehensive overview of circRNAs, covering their biogenesis, unique characteristics, functions, and turnover mechanisms. We also summarize the involvement of circRNAs in cancer hallmarks and their clinical relevance as biomarkers and therapeutic targets, especially in thyroid cancer (TC). Considering the potential of circRNAs as biomarkers and the fascination of circRNA-based therapeutics, the "Ying-Yang" dynamic regulations of circRNAs in TC warrant vastly dedicated investigations.

Circ_0001741 exerts as a tumor promoter in ovarian cancer through the regulation of miR-491-5p/PRSS8 axis

BACKGROUND

Circular RNAs (circRNAs) are important regulators for ovarian cancer (OC). Circ_0001741 has been found to be highly expressed in OC samples and is involved in regulating paclitaxel resistance in OC cells. Therefore, circ_0001741 may play a vital role in OC process, and its potential molecular mechanism is worth further revealing.

METHODS

Circ_0001741, miR-491-5p, and PRSS8 levels in OC tumor tissues and cells were quantified by quantitative real-time PCR or western blot. The proliferation, apoptosis and metastasis of OC cells were detected by cell counting kit 8 assay, Edu assay, flow cytometry, and transwell assay. RNA interaction was verified by dual-luciferase reporter assay and RIP assay. Xenograft assay was used to detect the effect of circ_0001741 knockdown on OC tumor growth in vivo.

RESULTS

Circ_0001741 was upregulated in OC tissues and cell lines. Knockdown of circ_0001741 repressed OC cell proliferation, metastasis, and enhanced apoptosis. Mechanistically, miR-491-5p was targeted by circ_0001741, and miR-491-5p inhibitor could attenuate the effect of circ_0001741 silencing on OC cell progression. Meanwhile, PRSS8 was a target of miR-491-5p, and miR-491-5p overexpression inhibited OC cell progression by targeting PRSS8. Circ_0001741 regulated PRSS8 expression by sponging miR-491-5p. Besides, circ_0001741 knockdown also inhibited OC tumor growth in vivo.

CONCLUSION

Our data showed that circ_0001741 could promote the growth and metastasis of OC cells through the miR-491-5p/PRSS8 axis, which provided a potential molecular target for the treatment of OC.

The role of genetic and epigenetic modifications as potential biomarkers in the diagnosis and prognosis of thyroid cancer

Thyroid cancer (TC) is the most common endocrine cancer, which contributes to more than 43,600 deaths and 586,000 cases worldwide every year. Among the TC types, PTC and FTC comprise 90% of all TCs. Genetic modifications in genes are responsible for encoding proteins of mitogen-associated protein kinase cascade, which is closely related with numerous cellular mechanisms, including controlling programmed cell death, differentiation, proliferation, gene expression, as well as in genes encoding the PI3K (phosphatidylinositol 3-kinase)/protein kinase B (AKT) cascade, which has contribution in controlling cell motility, adhesion, survival, and glucose metabolism, have been associated with the TC pathogenesis. Various genetic modifications including BRAF mutations, RAS mutations, RET mutations, paired-box gene 8/peroxisome proliferator-activated receptor-gamma fusion oncogene, RET/PTC rearrangements, telomerase reverse transcriptase mutations, neurotrophic tyrosine receptor kinase fusion genes, TP53 mutations, and eukaryotic translation initiation factor 1A X-linked mutations can effectively serve as potential biomarkers in both diagnosis and prognosis of TC. On the other hand, epigenetic modifications can lead to aberrant functions or suppression of a range of signalling cascades, which can ultimately result in cancer. Various studies have observed the link between epigenetic modification and multiple cancers including TC. It has been reported that several epigenetic alterations including histone modifications, aberrant DNA methylation, and epigenetic modulations of non-coding RNAs can play significant roles as potential biomarkers in the diagnosis and prognosis of TC. Therefore, a good understanding regarding the genetic and epigenetic modifications is not only essential for the diagnosis and prognosis of TC, but also for the development of novel therapeutics. In this review, most of the major TC-related genetic and epigenetic modifications and their potential as biomarkers for TC diagnosis and prognosis have been extensively discussed.

Circ_0004851 regulates the molecular mechanism of miR-296-3p/FGF11 in the influence of high iodine on PTC

The prevalence of papillary thyroid cancer (PTC) has been rising in recent years. Despite its relatively low mortality, PTC frequently metastasizes to lymph nodes and often recurs, posing significant health and economic burdens. The role of iodine in the pathogenesis and advancement of thyroid cancer remains poorly understood. Circular RNAs (circRNAs) are recognized to function as competing endogenous RNAs (ceRNAs) that modulate gene expression and play a role in various cancer stages. Consequently, this research aimed to elucidate the mechanism by which circRNA influences the impact of iodine on PTC. Our research indicates that high iodine levels can exacerbate the malignancy of PTC via the circ_0004851/miR-296-3p/FGF11 axis. These insights into iodine's biological role in PTC and the association of circRNA with the disease could pave the way for novel biomarkers and potentially effective therapeutic strategies to mitigate PTC progression.

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.

Dysregulation of the circ_0087502/miR-1179/TGFBR2 pathway supports gemcitabine resistance in pancreatic cancer

BACKGROUND

Circular RNAs (circRNAs) are a cohort of non-coding RNAs generated by back-splicing events. Accumulating evidence supports the crucial role of circRNAs in human tumorigenesis, metastasis, and chemoresistance. However, the role and mechanism of circRNA circ_0087502 in pancreatic cancer are yet unknown.

METHODS

The expression and function of circ_0087502 in pancreatic cancer were investigated using qRT-PCR and cell experiments. The predicted binding between circ_0087502 and microRNA-1179 (miR-1179), and between miR-1179 and TGFBR2, were examined using reporter assays.

RESULTS

Pancreatic cancer tissues and cell lines were discovered to express circ_0087502 at higher levels. Patients with pancreatic cancer who express circ_0087502 at high levels have a worse prognosis. In addition, circ_0087502 knockdown reduced the proliferation, migration, and invasion of pancreatic cancer cells and made them more sensitive to gemcitabine treatment. We found that circ_0087502 worked as a sponge for miR-1179, allowing miR-1179 to bind to the critical oncogene TGFBR2 in its 3'-untranslated region (3'-UTR). Pancreatic cancer cells were highly resistant to gemcitabine and had increased proliferation, migration, and invasion when miR-1179 was inhibited or overexpressed.

CONCLUSION

These results confirm that circ_0087502 activates the miR-1179/TGFBR2 axis to promote gemcitabine resistance in pancreatic cancer. Thus, our data might lay the groundwork for developing novel therapeutic strategies targeting circ_0087502 in pancreatic cancer patients.

Circ_LDLR promotes the progression of papillary thyroid carcinoma by regulating miR-1294/HMGB3 axis

Circular RNAs (circRNAs) have been found to be associated with the development and progression of cancers including papillary thyroid carcinoma (PTC). Circ_LDLR has been reported to be highly expressed in PTC, but its underlying mechanism of action has not been fully elucidated. This study aimed to investigate the role of circ_LDLR in PTC. The expression of circ_LDLR, miR-1294 and high mobility group box (HMGB) 3 was detected by quantitative real-time polymerase chain reaction (qRT-PCR). CCK-8 assay and transwell assays were employed to value cell viability, invasion and migration abilities. Western blot assay was to detect HMGB3 protein expression. Luciferase reporter gene and pull down assay were used to validate the interaction between miR-1294 and HMGB3 or circ_LDLR. Circ_LDLR showed high expression levels in PTC tissues and cells and knockdown of it inhibited the growth, invasion, and migration of PTC cells. In addition, miR-1294 was considered as a downstream target of circ_LDLR, and inhibition of miR-1294 partially reversed the inhibitory effects of circ_LDLR knockdown on PTC cells growth, invasion, and migration. More importantly, HMGB3 was identified as a downstream target of miR-1294. Our findings suggest circ_LDLR may plays a promoting role in PTC by downregulating miR-1294 and upregulating HMGB3 expression. Therefore, circ_LDLR may serve as a valuable prognostic biomarker and therapeutic target for PTC.

CircPI4KA Overexpression Enhances Carcinogenesis and Glycolysis Metabolism in Papillary Thyroid Carcinoma by Causing the miR-1287-5p-Mediated NRP2 Expression Elevation

Circular RNAs (circRNAs) are implicated in regulating the pathogenesis of papillary thyroid carcinoma (PTC). Herein, we aimed to investigate how circRNA phosphatidylinositol 4-kinase IIIα (circPI4KA, hsa_circ_0062389) functioned as an oncogene in PTC. CircPI4KA, microRNA-1287-5p (miR-1287-5p) and Neuropilin-2 (NRP2) level detection were completed by reverse transcription-quantitative polymerase chain reaction assay. Cell proliferation was assessed through Cell Counting Kit-8 assay, colony formation assay, and EdU assay. Transwell assay was used for detecting migration and invasion abilities. Cell migration was also determined by wound healing assay. Cell apoptosis was assessed using flow cytometry assay. The protein examination was performed using western blot. Glycolysis was evaluated via commercial kits. Dual-luciferase reporter assay and RNA immunoprecipitation assay were conducted for target analysis. The role of circPI4KA in vivo was explored and analyzed via tumor xenograft assay. CircPI4KA was significantly upregulated in PTC tissues and cells. Knockdown of circPI4KA suppressed proliferation, migration, invasion, glycolysis, and induced apoptosis of PTC cells. CircPI4KA interacted with miR-1287-5p in PTC cells. The antitumor function of circPI4KA downregulation was reversed by inhibition of miR-1287-5p. The miR-1287-5p directly targeted NRP2, and circPI4KA elevated the NRP2 expression by sponging miR-1287-5p. PTC progression was impeded by miR-1287-5p via targeting NRP2. Silencing circPI4KA inhibited tumor growth in vivo through the miR-1287-5p/NRP2 axis. The collective results revealed that circPI4KA induced the upregulation of NRP2 via sponging miR-1287-5p, thus acting as a carcinogenic factor in PTC.

New biomarkers: prospect for diagnosis and monitoring of thyroid disease

After the metabolic syndrome and its components, thyroid disorders represent the most common endocrine disorders, with increasing prevalence in the last two decades. Thyroid dysfunctions are distinguished by hyperthyroidism, hypothyroidism, or inflammation (thyroiditis) of the thyroid gland, in addition to the presence of thyroid nodules that can be benign or malignant. Thyroid cancer is typically detected via an ultrasound (US)-guided fine-needle aspiration biopsy (FNAB) and cytological examination of the specimen. This approach has significant limitations due to the small sample size and inability to characterize follicular lesions adequately. Due to the rapid advancement of high-throughput molecular biology techniques, it is now possible to identify new biomarkers for thyroid neoplasms that can supplement traditional imaging modalities in postoperative surveillance and aid in the preoperative cytology examination of indeterminate or follicular lesions. Here, we review current knowledge regarding biomarkers that have been reliable in detecting thyroid neoplasms, making them valuable tools for assessing the efficacy of surgical procedures or adjunctive treatment after surgery. We are particularly interested in providing an up-to-date and systematic review of emerging biomarkers, such as mRNA and non-coding RNAs, that can potentially detect thyroid neoplasms in clinical settings. We discuss evidence for miRNA, lncRNA and circRNA dysregulation in several thyroid neoplasms and assess their potential for use as diagnostic and prognostic biomarkers.

The Emerging Roles of circRNAs in Papillary Thyroid Carcinoma: Molecular Mechanisms and Biomarker Potential

Papillary thyroid carcinoma (PTC) is a common endocrine malignant tumor. The incidence of PTC has increased in the past decades and presents a younger trend. Accumulating evidence indicates that circular RNAs (circRNAs), featured with non-linear, closed-loop structures, play pivotal roles in tumorigenesis and regulate cell biological processes, such as proliferation, migration, and invasion, by acting as microRNA (miRNA) sponges. Additionally, due to their unique stability, circRNAs hold promising potential as diagnostic biomarkers and effective therapeutic targets for PTC treatment. In this review, we systematically arrange the expression level of circRNAs, related clinical characteristics, circRNA-miRNA-mRNA regulatory network, and molecular mechanisms. Furthermore, related signaling pathways and their potential ability of diagnostic biomarkers and therapeutic targets are discussed, which might provide a new strategy for PTC diagnosis, monitoring, and prognosis.

Circ_0002111 modulates the growth process of papillary thyroid carcinoma cells by targeting the miR-363-3p/HMGB1 axis

Previous studies have suggested that circular RNAs (circRNAs) are engaged in the progression of papillary thyroid carcinoma (PTC). However, the mechanism of circ_0002111 in PTC is still unclear. In this study, quantitative real-time PCR was carried out to measure the expressions of circ_0002111, microRNAs (miRNAs) and high-mobility group box 1 (HMGB1). Immunohistochemistry assay and western blot were applied for the determination of protein levels. The assays of 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide and thymidine analog 5-ethynyl-2'-deoxyuridine were deployed to assess PTC cell viability and proliferation, respectively. Besides, the capacities of cell apoptosis, invasion and angiogenesis were determined by flow cytometry, transwell and tube formation assays, respectively. Moreover, the interaction between miR-363-3p and circ_0002111 or HMGB1 was confirmed using a dual-luciferase reporter assay. Lastly, we established a xenograft model for the examination of the function of circ_0002111 in vivo. It was found that the expression of circ_0002111 was enhanced in PTC tissues and cells. Silencing circ_0002111 apparently retarded the viability, proliferation, invasion and tube formation, as well as expedited the apoptosis of PTC cells. Besides, circ_0002111 knockdown impeded the growth of the tumor in vivo. For mechanism analysis, circ_0002111 adjusted the expression of HMGB1 by sponge adsorption of miR-363-3p. Moreover, miR-363-3p inhibitor regained the influence of cellular malignant phenotype caused by circ_0002111 knockdown. Additionally, miR-363-3p overexpression impacted the cell functions by targeting HMGB1 in PTC. Thus, silencing circ_0002111 constrained the progression of PTC by the miR-363-3p/HMGB1 axis, which perhaps provided a novel idea of the therapeutic in PTC.

A Review and In Silico Analysis of Tissue and Exosomal Circular RNAs: Opportunities and Challenges in Thyroid Cancer

Simple Summary

Thyroid cancer is the most common endocrine neoplasm. Recently, knowledge of the molecular genetic changes of thyroid cancer has dramatically improved. Understanding the roles of these molecular changes in thyroid cancer tumorigenesis and progression is essential in developing a successful treatment strategy and improving disease outcomes. As a family of non-coding RNAs, circular RNAs (circRNAs) have been involved in several aspects of the physiological and pathological processes of the cells. The roles of circRNAs in cancer development and progress are evident. In the current review, we aimed to explore the clinical potential of circRNAs as potential diagnostic, prognostic, and therapeutic targets in thyroid cancer. Furthermore, screening the genome-wide circRNAs and performing functional enrichment analyses for all associated dysregulated circRNAs in thyroid cancer have been done. Given the unique advantages circRNAs have, such as superior stability, higher abundance, and presence in different body fluids, this family of non-coding RNAs could be promising diagnostic and prognostic biomarkers and potential therapeutic targets for thyroid cancer.

Abstract

Thyroid cancer (TC) is the most common endocrine tumor. The genetic and epigenetic molecular alterations of TC have become more evident in recent years. However, a deeper understanding of the roles these molecular changes play in TC tumorigenesis and progression is essential in developing a successful treatment strategy and improving patients’ prognoses. Circular RNAs (circRNAs), a family of non-coding RNAs, have been implicated in several aspects of carcinogenesis in multiple cancers, including TC. In the current review, we aimed to explore the clinical potential of circRNAs as putative diagnostic, prognostic, and therapeutic targets in TC. The current analyses, including genome-wide circRNA screening and functional enrichment for all deregulated circRNA expression signatures, show that circRNAs display atypical contributions, such as sponging for microRNAs, regulating transcription and translation processes, and decoying for proteins. Given their exceptional clinical advantages, such as higher stability, wider abundance, and occurrence in several body fluids, circRNAs are promising prognostic and theranostic biomarkers for TC.

GATA binding protein 1 recruits histone deacetylase 2 to the promoter region of nuclear receptor binding protein 2 to affect the tumor microenvironment and malignancy of thyroid carcinoma

The tumor microenvironment (TME) and activated angiogenesis in thyroid carcinoma (TC) are critical for tumor growth and metastasis. Nuclear receptor binding protein 2 (NRBP2) has been suggested as a tumor suppressor. This study examines the function of NRBP2 in the progression of TC and the regulatory mechanism. By analyzing bioinformatic tools including GSE165724 dataset and the Cancer Genome Atlas system, we predicted NRBP2 as a poorly expressed gene in TC. Decreased NRBP2 expression was detected in TC tumor tissues and cells. Poor expression of NRBP2 was linked to unfavorable prognosis of patients. GATA binding protein 1 (GATA1) was found as a negative regulator of NRBP2. It recruited histone deacetylase2 (HDAC2) to the NRBP2 promoter to trigger histone deacetylation. NRBP2 overexpression suppressed growth of TC cells, and it reduced expression of TME markers, M2 polarization of macrophages, and angiogenesis in TC. Similar results were reproduced in vivo in nude mice. However, the anti-oncogenic roles of NRBP2 were blocked after further overexpression of GATA1 or HDAC2. In summary, this study demonstrates that GATA1 recruits HDAC2 to the NRBP2 promoter and enhances the TME and angiogenesis in TC cells.

MicroRNA MiR-490-5p suppresses pancreatic cancer through regulating epithelial-mesenchymal transition via targeting MAGI2 antisense RNA 3

Pancreatic cancer with about 5% five-year overall survival rate remains a challenge. Invasion and migration of pancreatic cancer cells are the main factors leading to poor prognosis. MicroRNA-490-5p (miR-490-5p) has anti-cancer effects in a variety of tumors, but its role in pancreatic cancer has not been reported. The mRNA expressions of miR-490-5p, MAGI2 antisense RNA 3 (MAGI2-AS3), Matrix metalloproteinase (MMP)2, MMP9, N-cadherin, and E-cadherin were detected by quantitative real-time PCR, while the protein expressions of these genes except miR-490-5p were measured by Western blot analysis. The cell viability, apoptosis, migration and invasion were detected by cell counting kit-8 (CCK-8), apoptosis and transwell assays. MiR-490-5p was abnormally low-expressed in pancreatic cancer, whose down-regulation generated enhanced effects on viability, migration and invasion in pancreatic cancer cells, as well as MAGI2-AS3 expression. MiR-490-5p mimic exerted the opposite effect on cells, which also down-regulated MMP2, MMP9, and N-cadherin protein expressions, while up-regulating E-cadherin protein expression. MAGI2-AS3, which was the targeted binding site of miR-490-5p, promoted viability, migration and invasion, and inhibited apoptosis of cancer cells. More importantly, miR-490-5p played an anti-cancer role in pancreatic cancer by targeting MAGI2-AS3 and regulating epithelial-mesenchymal transition (EMT), which was partially offset by MAGI2-AS3.

Long non-coding RNA DCST1-AS1/hsa-miR-582-5p/HMGB1 axis regulates colorectal cancer progression

Long non-coding RNAs (lncRNAs) are related to the initiation and progression of tumor and regulate various cellular processes including growth, invasion, migration, and apoptosis. Understanding the roles and mechanisms of lncRNAs in regulating cancer progression is crucial for formulating novel therapeutic strategies. Although lncRNA DCST1-antisense RNA 1(AS1) has been implicated in several cancers, its role in the progression of colorectal cancer (CRC) remains to be explored. This study focuses on elucidating the function of lncRNA DCST1-AS1 in CRC development and its underlying mechanism. We found that the expression of lncRNA DCST1-AS1 was up-regulated in CRC tissues and cell lines, and CRC patients with high lncRNA DCST1-AS1 expression were associated with a poor prognosis. Loss-of-function and gain-of-function experiment in CRC cell lines confirmed that lncRNA DCST1-AS1 promoted the malignant phenotype of CRC cells, including cell proliferation, colony formation, migration, and invasion. In addition, we identified the binding sites between lncRNA DCST1-AS1 and hsa-miR-582-5p, and between hsa-miR-582-5p and High Mobility Group Box 1 (HMGB1) through DIANA Tools and TargetScan database, which was further confirmed by dual-luciferase reporter assay. Functional assay further confirmed the crucial role of lncRNA DCST1-AS1/hsa-miR-582-5p/HMGB1 axis in modulating the malignant phenotype of CRC cells. Collectively, our data suggest that lncRNA DCST1-AS1 regulates the aggressiveness of CRC cells through hsa-miR-582-5p/HMGB1 axis. Our study provides novel insight into the mechanism of lncRNA DCST1-AS1 in CRC cells for targeted therapy.

Circular RNA_0000326 promotes bladder cancer progression via microRNA-338-3p/ETS Proto-Oncogene 1/phosphoinositide-3 kinase/Akt pathway

Circular RNAs (circRNAs) play a pivotal regulatory role in bladder cancer (BC) occurrence and progression. The expression level, role and mechanism of circ_0000326 in BC remain unknown. In the present study, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was conducted to evaluate the expressions of circ_0000326, microRNA-338-3p (miR-338-3p) and ETS Proto-Oncogene 1(ETS1) mRNA in BC tissues and cell lines. Cell counting kit-8 (CCK-8) assay, wound healing assay and flow cytometry were used to detect the impacts of circ_0000326 on BC cell growth, migration and apoptosis. Western blot was used to detect the expressions of ETS1, phospho-phosphoinositide-3 kinase (p-PI3K), phospho-AKT, PI3K and AKT protein. Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed to analyze the biological function of ETS1 in BC. Here, we found that circ_0000326 expression was significantly elevated in BC cell lines and tissues, and circ_0000326 could promote BC cell growth and migration, and inhibit apoptosis. Dual-luciferase reporter gene assay confirmed that circ_0000326 and ETS1 could bind directly to miR-338-3p. Furthermore, circ_0000326 sponged miR-338-3p and up-regulated ETS1 expression. ETS1 was associated with the activation of PI3K/AKT pathway. Moreover, circ_0000326 could activate PI3K/AKT pathway by miR-338-3p/ETS1 axis. Collectively, circ_0000326/miR-338-3p/ETS1/PI3K/AKT pathway is involved in regulating BC progression.