Upregulated circular RNA circ_0025033 promotes papillary thyroid cancer cell proliferation and invasion via sponging miR-1231 and miR-1304

Role of circRNAs in regulating cell death in cancer: a comprehensive review

Despite multiple diagnostic and therapeutic advances, including surgery, radiation therapy, and chemotherapy, cancer preserved its spot as a global health concern. Prompt cancer diagnosis, treatment, and prognosis depend on the discovery of new biomarkers and therapeutic strategies. Circular RNAs (circRNAs) are considered as a stable, conserved, abundant, and varied group of RNA molecules that perform multiple roles such as gene regulation. There is evidence that circRNAs interact with RNA-binding proteins, especially capturing miRNAs. An extensive amount of research has presented the substantial contribution of circRNAs in various types of cancer. To fully understand the linkage between circRNAs and cancer growth as a consequence of various cell death processes, including autophagy, ferroptosis, and apoptosis, more research is necessary. The expression of circRNAs could be controlled to limit the occurrence and growth of cancer, providing a more encouraging method of cancer treatment. Consequently, it is critical to understand how circRNAs affect various forms of cancer cell death and evaluate whether circRNAs could be used as targets to induce tumor death and increase the efficacy of chemotherapy. The current study aims to review and comprehend the effects that circular RNAs exert on cell apoptosis, autophagy, and ferroptosis in cancer to investigate potential cancer treatment targets.

Hsa_circ_0092355 Accelerates Papillary Thyroid Cancer Progression by Regulating the miR-543/PDE5A Pathway

CircRNAs have been found to participate in the progression of various tumors. In the present study, we aimed to clarify the role of hsa_circ_0092355 in papillary thyroid cancer (PTC) cell development. RT-qPCR was used to determine the expression of hsa_circ_0092355, miR-543, and PDE5A. PTC cell proliferation was ascertained via a cell colony formation assay and the CCK-8 test. Western blotting was performed to examine the expression levels of PDE5A and apoptosis-associated proteins (Bcl-2 and Bax) in PTC cells. A scratch wound assay was performed to measure the migration of PTC cells. A mouse xenograft test was performed to assess the effects of hsa_circ_0092355 in vivo. RIP and dual-luciferase reporter assays confirmed the association between miR-543 and hsa_circ_0092355 or PDE5A. Associations between miR-543, hsa_circ_0092355, and PDE5A were evaluated using Pearson's correlation coefficient. Upregulation of hsa_circ_0092355 was observed in PTC tissues. The hsa_circ_0092355 knockdown blocked the proliferation and migration of PTC cells and induced apoptosis. Moreover, hsa_circ_0092355 knockdown blocked PTC xenograft tumor growth in vivo. The miR-543 inhibitor could reverse the changes induced by hsa_circ_0092355 knockdown by hsa_circ_0092355 targeting miR-543. Furthermore, miR-543 suppresses PTC progression by downregulating PDE5A expression. Our findings suggest that the PTC tumor promoter hsa_circ_0092355 may promote carcinogenesis by controlling the miR-543/PDE5A pathway.

CircRNA-regulated glucose metabolism in ovarian cancer: an emerging landscape for therapeutic intervention

Ovarian cancer (OC) has the highest mortality rate among female reproductive system tumours, with limited efficacy of traditional treatments and 5-year survival rates that rarely exceed 40%. Circular RNA (circRNA) is a stable endogenous circular RNA that typically regulates protein expression by binding to downstream miRNA. It has been demonstrated that circRNAs play an important role in the proliferation, migration, and glucose metabolism (such as the Warburg effect) of OC and can regulate the expression of glucose metabolism-related proteins such as GLUT1 and HK2, promoting anaerobic glycolysis of cancer cells, increasing glucose uptake and ATP production, and affecting energy supply and biosynthetic substances to support tumour growth and invasion. This review summarises the formation and characteristics of circRNAs and focuses on their role in regulating glucose metabolism in OC cells and their potential therapeutic value, providing insights for identifying new therapeutic targets.

Emerging roles of circular RNAs in the invasion and metastasis of head and neck cancer: Possible functions and mechanisms

Head and neck cancer (HNC) is the seventh most prevalent malignancy worldwide in 2020. Cancer metastasis is the main cause of poor prognosis in HNC patients. Recently, circular RNAs (circRNAs), initially thought to have no biological function, are attracting increasing attention, and their crucial roles in mediating HNC metastasis are being extensively investigated. Existing studies have shown that circRNAs primarily function through miRNA sponges, transcriptional regulation, interacting with RNA-binding proteins (RBPs) and as translation templates. Among these functions, the function of miRNA sponge is the most prominent. In this review, we summarized the reported circRNAs involved in HNC metastasis, aiming to elucidate the regulatory relationship between circRNAs and HNC metastasis. Furthermore, we summarized the latest advances in the epidemiological information of HNC metastasis and the tumor metastasis theories, the biogenesis, characterization and functional mechanisms of circRNAs, and their potential clinical applications. Although the research on circRNAs is still in its infancy, circRNAs are expected to serve as prognostic markers and effective therapeutic targets to inhibit HNC metastasis and significantly improve the prognosis of HNC patients.

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.

Multiomics dynamic learning enables personalized diagnosis and prognosis for pancancer and cancer subtypes

Artificial intelligence (AI) approaches in cancer analysis typically utilize a 'one-size-fits-all' methodology characterizing average patient responses. This manner neglects the diverse conditions in the pancancer and cancer subtypes of individual patients, resulting in suboptimal outcomes in diagnosis and treatment. To overcome this limitation, we shift from a blanket application of statistics to a focus on the explicit recognition of patient-specific abnormalities. Our objective is to use multiomics data to empower clinicians with personalized molecular descriptions that allow for customized diagnosis and interventions. Here, we propose a highly trustworthy multiomics learning (HTML) framework that employs multiomics self-adaptive dynamic learning to process each sample with data-dependent architectures and computational flows, ensuring personalized and trustworthy patient-centering of cancer diagnosis and prognosis. Extensive testing on a 33-type pancancer dataset and 12 cancer subtype datasets underscored the superior performance of HTML compared with static-architecture-based methods. Our findings also highlighting the potential of HTML in elucidating complex biological pathogenesis and paving the way for improved patient-specific care in cancer treatment.

Microarray profiling identifies hsa_circ_0082003 as a novel tumor promoter for papillary thyroid carcinoma

BACKGROUND

Circular RNAs (circRNAs) are non-coding RNAs that have essential regulatory roles in the development of various tumors. This study explored whether circRNAs are involved in the progression of papillary thyroid carcinoma (PTC).

METHODS

Differentially expressed circRNAs (DECs) in four pairs of PTC and matched normal thyroid tissues were screened using a circRNA microarray. The potential functions of dysregulated circRNAs were predicted by bioinformatic analyses. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to determine hsa_circ_0082003 expression in 80 pairs of PTC and matched normal thyroid tissues. Cell counting kit-8, colony formation, wound healing, and Transwell assays were performed to evaluate the biological functions of hsa_circ_0082003 in PTC cells. The role of hsa_circ_0082003 in PTC tumorigenesis in vivo was validated in nude mice.

RESULTS

In total, 3150 DECs (2317 upregulated and 833 downregulated) were identified. Pathway enrichment analyses indicated that the dysregulated circRNAs may play roles in PTC development. RT-qPCR validation demonstrated that hsa_circ_0082003 expression was significantly increased in PTC tissues and correlated with poor clinicopathological parameters. Receiver operating characteristic curve analysis showed that hsa_circ_0082003 had good performance for diagnosing PTC and judging whether it was accompanied by lymph node metastasis. Knockdown of hsa_circ_0082003 inhibited PTC cell proliferation, migration, and invasion. Tumor formation assays in vivo showed that downregulation of hsa_circ_0082003 significantly suppressed the growth of PTC.

CONCLUSION

Hsa_circ_0082003 may serve as a novel diagnostic biomarker and potential therapeutic target for PTC.

circRNA mannosidase alpha class 1A member 2 contributes to the proliferation and motility of papillary thyroid cancer cells through upregulating metadherin via absorbing microRNA-449a

Papillary thyroid carcinoma (PTC) is a common malignancy in endocrine system globally. Accumulating articles have found that circular RNAs (circRNAs) were dysregulated, and they were involved in PTC development. The aim of this project was to explore the function and associated mechanism of circRNA mannosidase alpha class 1A member 2 (circMAN1A2) in PTC progression. The expression of RNA was determined by real-time quantitative PCR. Cell proliferation ability was analyzed by colony formation assay and 5-ethynyl-2'-deoxyuridine assay. Cell migration and invasion were assessed by wound healing assay and transwell invasion assay, respectively. Protein levels were determined by Western blot assay. Dual-luciferase reporter assay and RNA immunoprecipitation assay were applied to confirm the interaction between microRNA-449a (miR-449a) and circMAN1A2 or metadherin (MTDH). Xenograft tumor model was utilized to explore the effect of circMAN1A2 silencing on tumor growth in vivo . CircMAN1A2 expression was elevated in PTC specimens and three PTC cell lines relative to adjacent normal specimens and Nthy-ori 3-1 cell line. CircMAN1A2 silencing inhibited the proliferation and motility of PTC cells. CircMAN1A2 acted as a molecular sponge of miR-449a, and circMAN1A2 knockdown suppressed PTC development partly through upregulating miR-449a. MiR-449a bound to the 3' untranslated region of MTDH, and miR-449a restrained PTC progression partly through down-regulating MTDH. CircMAN1A2 interference suppressed PTC progression in vivo . CircMAN1A2 contributed to the proliferation ability and motility of PTC cells through enhancing MTDH expression via sponging miR-449a.

Exosomal miR-1304-3p promotes breast cancer progression in African Americans by activating cancer-associated adipocytes

Breast cancer displays disparities in mortality between African Americans and Caucasian Americans. However, the exact molecular mechanisms remain elusive. Here, we identify miR-1304-3p as the most upregulated microRNA in African American patients. Importantly, its expression significantly correlates with poor progression-free survival in African American patients. Ectopic expression of miR-1304 promotes tumor progression in vivo. Exosomal miR-1304-3p activates cancer-associated adipocytes that release lipids and enhance cancer cell growth. Moreover, we identify the anti-adipogenic gene GATA2 as the target of miR-1304-3p. Notably, a single nucleotide polymorphism (SNP) located in the miR-1304 stem-loop region shows a significant difference in frequencies of the G allele between African and Caucasian American groups, which promotes the maturation of miR-1304-3p. Therefore, our results reveal a mechanism of the disparity in breast cancer progression and suggest a potential utility of miR-1304-3p and the associated SNP as biomarkers for predicting the outcome of African American patients.

circ_0025033 promotes ovarian cancer development via regulating the hsa_miR-370-3p/SLC1A5 axis

BACKGROUND

Circular RNAs (circRNAs) appear to be important modulators in ovarian cancer. We aimed to explore the role and mechanism of circ_0025033 in ovarian cancer.

METHODS

qRT-PCR was conducted to determine circ_0025033, hsa_miR-370-3p, and SLC1A5 mRNA expression. Functional experiments were conducted, including Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, transwell, tube formation, xenograft tumor model assay, western blot analysis of protein levels, and analysis of glutamine metabolism using commercial kits. Their predicted interaction was confirmed using dual-luciferase reporter and RNA pull-down.

RESULTS

circ_0025033 was upregulated in ovarian cancer; its knockdown induced proliferation, invasion, angiogenesis, glutamine metabolism, and apoptosis in vitro, and blocked tumor growth in vivo. circ_0025033 regulated ovarian cancer cellular behaviors via sponging hsa_miR-370-3p. In parallel, SLC1A5 might abolish the anti-ovarian cancer role of hsa_miR-370-3p. Furthermore, circ_0025033 affected SLC1A5 via regulating hsa_miR-370-3p.

CONCLUSION

circ_0025033 might promote ovarian cancer progression via hsa_miR-370-3p/SLC1A5, providing an interesting insight into ovarian cancer tumorigenesis.

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.

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.

Circ-FOXM1 promotes the proliferation, migration and EMT process of osteosarcoma cells through FOXM1-mediated Wnt pathway activation

BACKGROUND

Osteosarcoma (OS) is a malignant bone tumor that commonly occurs in adolescents with a high mortality rate and frequent pulmonary metastasis. Emerging evidence has suggested that circular RNAs (circRNAs) are important regulators in multiple biological activities of carcinomas. Nevertheless, the role of circRNAs derived from forkhead box M1 (FOXM1), a well-accepted modulator of OS progression, has not been discussed in OS.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was utilized to test circ-FOXM1 (hsa_circ_0025033) expression in OS cell lines. Cell counting kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), transwell assays and western blot analysis of epithelial-mesenchymal transition (EMT) markers were conducted to evaluate cell proliferation, apoptosis, migration, and EMT process. Luciferase reporter assay and RNA-binding protein immunoprecipitation (RIP) assay were utilized to detect the interaction of circ-FOXM1 and RNAs.

RESULTS

High expression of circ-FOXM1 was detected in OS cell lines. Functionally, circ-FOXM1 knockdown inhibited the proliferation, migration and EMT process, whereas induced the apoptosis of OS cells. From the aspect of molecular mechanism, circ-FOXM1 was discovered to upregulate FOXM1 expression via sponging miR-320a and miR-320b, therefore activating Wnt signaling pathway. Besides, rescue experiments elucidated that circ-FOXM1 regulated cellular activities of OS cells via FOXM1. Further, in vivo assays supported that loss of circ-FOXM1 restrained OS tumor growth.

CONCLUSION

Circ-FOXM1 facilitated the malignant phenotypes of OS cells through FOXM1-mediated Wnt pathway activation, revealing circ-FOXM1 as a potential biomarker for OS treatment.

CircSND1/miR-182-5p Axis Promotes Proliferative and Invasive Abilities of Thyroid Cancer via Binding Targeting MET

Objective. To monitor the impacts of circSND1 upon thyroid cancer (TC) tissues and cells and its mechanisms. Methods. Thiazole blue (MTT) was adopted to monitor the impacts of circSND1 upon the proliferative abilities of TPC-1 and SW1736 cells. 5-Bromodeoxyuridine (BrdU) combined with flow cytometry was adopted to monitor the impacts of circSND1 upon the DNA synthesis of TPC-1 and SW1736 cells. We adopted transwell experiment to examine the impacts of circSND1 on cell invasive abilities of TPC-1 and SW1736 cells. The mRNA quantitative levels of circSND1, miR-182-5p, and mesenchymal epidermal transformation factor (MET) in TC tissues were detected by qRT-PCR experiment. We also adopted luciferase assay to verify the targeting interaction between miR-182-5p and MET or miR-182-5p and circSND1. Results. CircSND1 mRNA and MET mRNA were upregulated in thyroid cancer tissues. MiR-182-5p quantification was attenuated in thyroid cancer tissues. Downregulation of circSND1 suppressed TC progression in vivo and in vitro. Furthermore, luciferase report assay uncovered that miR-182-5p was a direct binding target of circSND1 and MET was a direct binding target of miR-182-5p. Besides, circSND1 regulated MET expression and thyroid cancer cell function via binding miR-182-5p. Conclusion. Overexpression of circSND1 in TC tissues and cells facilitates TC tumorigenesis and metastasis via suppressing the quantitative level of miR-182-5p and inducing the upregulation of MET mRNA and protein expression, which expected to offer fresh clues for the administration of TC.

Circular RNAs and thyroid cancer: closed molecules, open possibilities

Thyroid neoplasms requiring differential diagnosis between thyroid cancer and benign tumors can be detected in more than half of the healthy population. A generally accepted method that allows assessing the risk of malignant potential and determining the indications for surgical treatment of thyroid tumor is a fine-needle aspiration biopsy followed by a cytological examination. Nevertheless, in patients with indeterminate categories of cytological conclusions according to Bethesda system, the positive predictive value of the cytology result is significantly lower than desired and often leads to unjustified surgical treatment. In this regard, the search for alternative diagnostic solutions continues. Circular RNAs are a group of non-coding RNAs distinguished by a closed structure formed by covalent bonding of the nucleotide chain ends. Recent studies allow us to conclude that many different circular RNAs are involved in processes mediating oncogenesis in the thyroid gland, and their altered expression in tissue, blood, and exosomes of plasma may be a characteristic sign of thyroid cancer and certain clinicopathological features of its course. The purpose of this review is to analyze the accumulated data on the association of various circular RNAs with thyroid cancer and to discuss possible ways to improve the diagnosis and treatment of the disease based on the assessment of the expression of these molecules.

Circular RNA_0057209 Acts as ceRNA to Inhibit Thyroid Cancer Progression by Promoting the STK4-Mediated Hippo Pathway via Sponging MicroRNA-183

Thyroid cancer is the most common malignancy of the endocrine system, and its outcome remains unsatisfactory. In recent years, circular RNAs (circRNAs) have emerged as crucial regulators in cancers. In the current study, we aimed to investigate whether and how circRNA_0057209 functioned in thyroid cancer. Initial results revealed that circRNA_0057209 and STK4 were both reduced, while miR-183 was up-regulated in thyroid cancer tissues and cells. Experiments including RNA pull-down and RIP assays further identified that upregulation of circRNA_0057209 augmented the expression of STK4, a target gene of miR-183, by competitively-binding to miR-183. Furthermore, functional experiments provided evidence that overexpression of circRNA_0057209 not only inhibited the proliferative, migratory, and invasive properties of thyroid cancer cells while facilitating their apoptosis but also delayed tumor growth. Conversely, upregulation of miR-183 or silencing of STK4 reversed the changes induced by circRNA_0057209. Meanwhile, mechanistic experimentation demonstrated that circRNA_0057209 promoted STK4 expression by sponging miR-183, while STK4 enhanced YAP phosphorylation to mediate the Hippo pathway, thereby suppressing tumor progression. Altogether, our findings indicated that circRNA_0057209 may serve as a competing endogenous RNA of miR-183 to increase STK4 expression, thus inhibiting the development of thyroid cancer.

Circ_0025033 deficiency suppresses paclitaxel resistance and malignant development of paclitaxel-resistant ovarian cancer cells by modulating the miR-532-3p/FOXM1 network

BACKGROUND

Ovarian cancer (OC) is the main cause of cancer-related death in women, and drug resistance is a leading cause of treatment failure. Recently, the involvement of circular RNAs (circRNAs) in cancer progression has become an area of increased investigation. The objective of this study is to uncover the function and regulatory mechanism of circ_0025033 in paclitaxel (PTX)-resistant OC cells.

METHODS

The expression of circ_0025033, FOXM1 and miR-532-3p was investigated using quantitative real-time polymerase chain reaction (qRT-PCR), and the protein expression of FOXM1 was quantified by western blot. Cell biological functions, including cell viability, migration/invasion and apoptosis, were explored using 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assays, transwell assays and flow cytometry assays. The interaction between miR-532-3p and circ_0025033 or FOXM1 predicted by bioinformatics analysis was validated by pull-down assay and dual-luciferase reporter assay. Exosomes were isolated to determine the further function of circ_0025033.

RESULT

Circ_0025033 and FOXM1 were highly expressed, while miR-532-3p was poorly expressed in OC tissues and cells, and the expression pattern was greater in PTX-resistant OC cells. Circ_0025033 knockdown lessened PTX resistance, suppressed migration/invasion and promoted apoptosis of PTX-resistant cells. With respect to mechanism, circ_0025033 upregulated the expression of FOXM1 by targeting miR-532-3p, and circ_0025033 knockdown blocked the malignant activities of PTX-resistant OC cells by enriching miR-532-3p and suppressing FOXM1. Exosomes derived from PTX-resistant cells with circ_0025033 knockdown also could repress the malignant actions of PTX-resistant OC cells.

CONCLUSION

Circ_0025033 downregulation impaired PTX resistance and malignant activities of PTX-resistant OC cells by regulating the miR-532-3p/FOXM1 network.

Circ_0006948 Contributes to Cell Growth, Migration, Invasion and Epithelial-Mesenchymal Transition in Esophageal Carcinoma

BACKGROUND

Circular RNAs (circRNAs) can act as promoters or inhibitors in cancer progression. Has_circ_0006948 (circ_0006948) was reported to aggravate the malignant behaviors of esophageal carcinoma (EC).

AIMS

This study focused on investigating the molecular mechanism of circ_0006948 in EC progression.

METHODS

The quantitative real-time polymerase chain reaction was performed to detect the expression of circ_0006948, microRNA-4262 (miR-4262) and fibronectin type III domain containing 3B (FNDC3B). Cell growth analysis was conducted by Cell Counting Kit-8 and colony formation assays. Cell migration and invasion were assessed by transwell assay. Epithelial-mesenchymal transition (EMT)-associated proteins and FNDC3B protein expression were assayed using western blot. Dual-luciferase reporter and RNA pull-down assays were performed to validate the target combination. Xenograft tumor assay was used for investigating the role of circ_0006948 in vivo.

RESULTS

Circ_0006948 was upregulated in EC tissues and cells. Downregulating the expression of circ_0006948 or FNDC3B repressed cell growth, migration, invasion and EMT in EC cells. Target analysis indicated that miR-4262 was a target for circ_0006948 and FNDC3B was a downstream gene for miR-4262. Moreover, circ_0006948 could affect the expression of FNDC3B via sponging miR-4262. The effects of si-circ_0006948#1 on EC cells were partly restored by miR-4262 inhibition or FNDC3B overexpression. In addition, circ_0006948 also facilitated EC tumorigenesis in vivo by targeting the miR-4262/FNDC3B axis.

CONCLUSION

Taken together, circ_0006948 functioned as an oncogenic factor in EC by the miR-4262-mediated FNDC3B expression regulation.

Circular RNA circ_0000644 promotes papillary thyroid cancer progression via sponging miR-1205 and regulating E2F3 expression

The dysregulation of circular RNAs (circRNAs) facilitates the tumorigenesis of papillary thyroid carcinoma (PTC). This study was targeted at determining the functions and mechanism of circ_0000644 in regulating PTC development. Circ_0000644, microRNA-1205 (miR-1205) and E2F transcription factor 3 (E2F3) expressions were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Actinomycin D (ActD) and Ribonuclease R (RNase R) assays were used to verify the circular characteristic of circ_0000644. After circ_0000644 was knocked down, PTC cell growth, migration, invasion and apoptosis were assessed by cell counting kit-8 (CCK-8) assay, Transwell assay and flow cytometry analysis, respectively. The regulating relationships among circ_0000644, E2F3 and miR-1205 were confirmed through RNA immunoprecipitation (RIP) assay and dual-luciferase reporter assay. Besides, the regulatory effects of circ_0000644 on the protein level of E2F3 was analyzed via Western blot. In PTC, circ_0000644 was highly expressed, and it was located mainly in the cytoplasm, and it had stable structure. The knockdown of circ_0000644 repressed PTC cell growth, migration, and invasion, and facilitated apoptosis. Circ_0000644 could directly interact with miR-1205 to repress the expression of miR-1205, and it served as a miR-1205 sponge to modulate E2F3 expression in PTC cells. Circ_0000644 up-regulates E2F3 expression via sponging miR-1205 to promote PTC progression.

Circ_0079558 promotes papillary thyroid cancer progression by binding to miR-26b-5p to activate MET/AKT signaling

Circular RNAs (circRNAs) are a group of non-coding RNAs featured by covalently closed circular structure. CircRNA_0079558 (circ_0079558) is derived from RAPGEF5 gene, and it has been found to be significantly up-regulated in papillary thyroid carcinoma (PTC). However, the role and working mechanism of circ_0079558 in PTC progression have never been illustrated. The levels of circ_0079558 and MET proto-oncogene, receptor tyrosine kinase (MET) were up-regulated in PTC tissues and cell lines, as evidenced by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot assay. The silencing of circ_0079558 or MET restrained cell proliferation, migration and invasion whereas triggered cell apoptosis in PTC cells, as verified by Cell Counting Kit-8 (CCK8) assay, plate colony formation assay, transwell invasion assay, wound healing assay and flow cytometry. Through using MET specific inhibitor PHA665752, we found that circ_0079558 overexpression enhanced the malignant behaviors of PTC cells through activating MET/AKT pathway. Through dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay, microRNA-26b-5p (miR-26b-5p) was identified to be the intermediary molecular between circ_0079558 and MET, and circ_0079558 knockdown reduced the expression of MET partly through elevating miR-26b-5p in PTC cells. The miR-198/FGFR1 pathway was identified as another signal axis downstream of circ_0079558, and the co-overexpression of FGFR1 and MET largely rescued the proliferation ability of circ_0079558-silenced PTC cells. Through xenograft tumor model, we found that circ_0079558 silencing restrained xenograft tumor growth in vivo. In conclusion, circ_0079558 facilitated the proliferation and motility whereas inhibited the apoptosis of PTC cells largely through mediating miR-26b-5p/MET/AKT signaling.

Circular RNA circKIF4A facilitates the malignant progression and suppresses ferroptosis by sponging miR-1231 and upregulating GPX4 in papillary thyroid cancer

Circular RNAs (circRNAs) are one type of non-coding RNA. They act as important role in regulating various biological processes in the malignant progression. But we don't clearly know the specific mechanism of the majority circRNAs in papillary thyroid tumor progression. In the current study, we explored circKIF4A and the result showed that it had high expression in papillary thyroid cancer. The functions of circKIF4A were explored by CCK-8, transwell, and mouse xenograft experiments. Knockdown of circKIF4A could suppress papillary thyroid cell growth and migration. In addition, RIP assays and dual luciferase vector reporter assays were further conducted. Our consequence showed circKIF4A facilitated the malignant progress of papillary thyroid tumor by sponging miR-1231 and upregulating GPX4 expression. In conclusion, our study proved that circKIF4A-miR-1231-GPX4 axis played a vital role in cancer proliferation and ferroptosis by competing endogenous RNAs. Therefore, targeting circKIF4A is very likely to be a potential method for treatment of papillary thyroid cancer in the future.

Emerging roles of circular RNAs in thyroid cancer

As the most common endocrine-related malignant tumor, the prevalence of thyroid cancer (TC) has soared strikingly over the past thirty years then verged to stabilization or even descension temporally. Distributed in a cell-specific manner, circular RNAs (circRNAs) is a novel class of non-coding RNAs characterized by its covalently closed loop without 5'-terminal cap and 3'-terminal poly A tail, which guarantee its distinctive evolutionary conservation and exonucleases resistance. Emerging evidence indicates that circRNA participates in the pathogenesis and carcinogenesis of several cancers including thyroid cancer. In this review, we concentrated on the connection between circRNAs and thyroid cancer so as to obtain a more profound understanding. We aim to discuss this relationship between TC and circRNAs by summarizing the effect of various circRNAs on tumor biological behaviors and clinical application, and systematically outlook the conceivable application of circRNAs in TC diagnosis and therapy.

Advances of circular RNAs in thyroid cancer: An overview

Circular RNA (circRNA) is a general term for a type of single-stranded RNAs, they are primarily generated via exon back-splice process in precursor mRNAs (pre-mRNAs). circRNAs refer to an emerging type of endogeneity-correlated closed molecules of RNA in a covalent manner. They mainly function as microRNA sponges, protein brackets, and regulatory element in transcription and splicing process. Recently, it has also starting been noticed that they serve as extraordinary models involved in polypeptides producing process. Although circRNAs have been extensively studied, their function in thyroid carcinoma is still lacking. Thus, we present the latest advances in circRNA research and summarize their fundamental rules of regulating process as well as the mechanism. More importantly, We mainly review the role and mechanism of circRNA in thyroid cancer, which provides an emerging perspective and theoretically supports the treatment of thyroid cancer.

Circular RNA circ-NCOR2 accelerates papillary thyroid cancer progression by sponging miR-516a-5p to upregulate metastasis-associated protein 2 expression

Objective

Papillary thyroid cancer (PTC) is one of the most prevalent endocrine malignancies and the fifth most common cancer in women. Circular RNAs (circRNAs) have been shown to play vital functions in cancers, but few studies have focused on the functions and mechanism of dysregulated circRNAs in PTC.

Methods

Quantitative reverse transcription PCR was used to measure circ-NCOR2 levels in PTC tissues and cell lines. The functions of circ-NCOR2 in PTC were examined by analysis using the cell counting kit-8, clone forming, flow cytometry, and Transwell experiments. Bioinformatic analysis and dual luciferase reporter gene testing were used to identify the mechanisms of circ-NCOR2.

Results

Circ-NCOR2 overexpression was observed in PTC tissues and cells. Silenced or overexpressed expression of circ-NCOR2 strikingly attenuated or facilitated, respectively, the growth, migration, and invasion of PTC cells. Mechanistically, miR-615a-5p was identified as the target of circ-NCOR2. Moreover, circ-NCOR2 enhanced the expression of metastasis-associated protein 2 (MTA2) by sponging miR-615a-5p, thereby facilitating PTC cell progression.

Conclusions

Taken together, our findings reveal a novel circ-NCOR2/miR-615a-5p/MTA2 axis in PTC, which could become a potential therapeutic target for this disease.

Emerging Roles of Circular RNAs in Thyroid Cancer

Thyroid cancer (TC) has the highest incidence among endocrine malignancies. Thus, it is essential to achieve a deep understanding of various mechanisms of development and progression of TC. circRNAs are recognized by multiple studies as being dysregulated in TC. Accumulating evidences have revealed that circRNAs serve as regulatory molecules involved in various biological processes in TC, including cell proliferation, apoptosis, invasion/migration, metabolism, and chemoresistance. Furthermore, circRNA can also serve as an effective tool in TC researches of diagnosis, prognosis, and treatments. Thus, this review is to outline the characteristics of circRNAs, generalize their categories and functions, and highlight the expression of circRNAs in TC. Meanwhile, we are expecting to achieve a comprehensive understanding of new therapies based on circRNAs in treating or preventing TC.

The emerging function and clinical significance of circRNAs in Thyroid Cancer and Autoimmune Thyroid Diseases

Thyroid cancer (TC) is one of the most common malignant tumors, with high morbidity and mortality rates worldwide. The incidence of TC, especially that of papillary thyroid carcinoma (PTC); has increased rapidly in recent decades. Autoimmune thyroid disease (AITD) is closely related to TC and has an estimated prevalence of 5%. Thus, it is becoming increasingly important to identify potential diagnostic biomarkers and therapeutic targets for TC and AITD. Circular RNAs (circRNAs) are a class of non-coding RNAs with covalently bonded circular structures that lack 5'-3' polarity and polyadenylated tails. Several circRNAs play crucial roles in the development of various diseases, including TC and AITD, and could be important new biomarkers and/or targets for the diagnosis and therapy of such disorders. Although there are four subtypes of TC, research on circRNA has largely focused on its connection to PTC. Therefore, this review mainly summarizes the relationships between circRNAs and PTC and AITD, including the molecular mechanisms underlying these relationships. In particular, the functions of “miRNA sponges” and their interactions with proteins and RNA are discussed. The possible targeting of circRNAs for the prevention, diagnosis, and treatment of TC and AITD is also described. CircRNAs could be potential biomarkers of TC and AITD, although validation will be required before they can be implemented in clinical practice.

circ-PSD3 promoted proliferation and invasion of papillary thyroid cancer cells via regulating the miR-7-5p/METTL7B axis

Papillary thyroid cancer (PTC) is a common tumor malignancy of the endocrine system worldwide. Recently, circular RNAs (circRNAs) have been reported to participate in diverse pathological processes, especially in tumorigenesis. However, the functional role and mechanism of circRNA pleckstrin and Sec7 domain containing 3 (circ-PSD3) in PTC are still unclear. In this study, qRT-PCR results showed that circ-PSD3 was significantly upregulated in PTC tissues and cell lines. Meanwhile, circ-PSD3 overexpression was positively associated with larger tumor size, TNM stage, and lymph node metastasis. Knockdown of circ-PSD3 suppressed the proliferation and invasion of PTC cells. Besides, circ-PSD3 interacted with miR-7-5p to reduce its expression, and methyltransferase like 7B (METTL7B) was verified as a target gene of miR-7-5p. Functionally, inhibition of circ-PSD3 impeded PTC cell proliferation and invasion via targeting miR-7-5p to downregulate METTL7B expression. Taken together, silencing of circ-PSD3 hampered the proliferation and invasion of PTC cells via upregulating the inhibitory effect of miR-7-5p on METTL7B expression. Therefore, circ-PSD3 could be a potential diagnostic biomarker or molecular treatment target for PTC.

hsa_circ_0001018 promotes papillary thyroid cancer by facilitating cell survival, invasion, G1/S cell cycle progression, and repressing cell apoptosis via crosstalk with miR-338-3p and SOX4

We identified a novel interactome, circ_0001018/miR-338-3p/SOX4, in papillary thyroid cancer (PTC), and we intended to confirm the regulatory relationship between the three and to study the effects of the three in PTC. The bioinformatics method was used to screen out the circular RNA and mRNA of interest. A cellular fractionation assay and fluorescence in situ hybridization (FISH) assay were conducted to prove that circ_0001018 and CCT4 (the host gene of circ_0001018) mRNA primarily localized in the cytoplasm of PTC cell lines. By qRT-PCR analysis, the expression of circ_0001018 and SOX4 mRNA was found upregulated while the expression of miR-338-3p was found downregulated in PTC tissues and cells. circ_0001018 silence significantly inhibited the tumor growth in xenografted nude mice. A series of cytological experiments such as a Cell Counting Kit-8 (CCK-8) assay, a 5-ethynyl-2′-deoxyuridine (EdU) assay, cell cycle profiling, wound healing, a transwell assay, and cell apoptosis were conducted and showed that circ_0001018 and SOX4 promoted cell proliferation, migration, and invasion, inhibited cell apoptosis, and reduced the cell cycle arrest at the G₁ phase in PTC cells. Compared with circ_0001018 and SOX4, miR-338-3p held the opposite function. The regulatory relationship between circ_0001018 and miR-338-3p, and between miR-338-3p and SOX4 mRNA, was validated using a luciferase reporter gene assay and/or RNA immunoprecipitation (RIP assay). Our findings showed that circ_0001018 acted as the tumor promoter via sponging miR-338-3p to elevate SOX4 expression level in PTC. Importantly, this novel circ_0001018/miR-338-3p/SOX4 axis has the potential to be considered as a therapy target for PTC.

miR-19a-3p Facilitates Lung Adenocarcinoma Cell Phenotypes by Inhibiting TEK

Background: Both TEK and miR-19a-3p have been reported to regulate lung adenocarcinoma (LUAD) progression. However, the association between TEK and miR-19a-3p in LUAD remained unknown. This research aimed to investigate a novel miR-19a-3p/TEK interactome in LUAD cells. Methods: The mRNA expression and protein expression in the cell lines were determined using qPCR and Western blot assay, respectively. CCK-8 assay, EDU assay, flow cytometry cell apoptosis assay, scratch assay, and cell-to-extracellular matrix adhesion assay were performed to detect the proliferation, apoptosis, migration, and adhesion ability of A549 and H1975 cell lines. Results: Findings revealed that both mRNA and protein levels of TEK were downregulated in the LUAD tumor tissues and cell lines. It was also found that compared with the control group, the transfection of TEK overexpression plasmids into H1975 and A549 cell lines significantly inhibited cancerous phenotypes. However, experimental results indicated that by downregulating TEK, miR-19a-3p promoted LUAD cell phenotypes. Conclusion: This research demonstrated that an interactome existed between miR-19a-3p and TEK and that miR-19a-3p could suppress LUAD tumors by inhibiting TEK. This novel interactome could be used as a novel therapy target for LUAD.

Circ-FOXM1 knockdown suppresses non-small cell lung cancer development by regulating the miR-149-5p/ATG5 axis

Circular RNAs (circRNAs) have been reported to be related to the development of human cancers. However, the function of circ-FOXM1 in non-small cell lung cancer (NSCLC) was largely unknown. Here, we revealed the role and functional mechanism of circ-FOXM1 in NSCLC progression. The relative expression of circ-FOXM1, microRNA-149-5p (miR-149-5p), and autophagy-related 5 (ATG5) was determined by quantitative real-time polymerase chain reaction (RT-qPCR). Cell Counting Kit-8 (CCK-8), flow cytometry, and transwell assay were employed to assess cell viability, apoptosis, and migration, respectively. The relative protein expression was detected by western blot. Furthermore, mouse xenograft was carried out to analyze the effect of circ-FOXM1 on tumor growth in vivo. In addition, the interaction between miR-149-5p and circ-FOXM1 or ATG5 was predicted by Starbase3.0 and confirmed by the dual-luciferase reporter assay and RNA pull-down assay. Circ-FOXM1 and ATG5 levels were upregulated, while the miR-149-5p level was downregulated in NSCLC tissues and cells. Circ-FOXM1 knockdown suppressed NSCLC cell viability, migration, and autophagy, and induced cell apoptosis. Interestingly, circ-FOXM1 targeted miR-149-5p to upregulate the ATG5 level. Moreover, circ-FOXM1 exerted function through repressing miR-149-5p expression, and miR-149-5p exerted function via inhibiting ATG5 expression. Our results suggested that circ-FOXM1 knockdown attenuated the development of NSCLC through modulating the miR-149-5p/ATG5 axis, providing a theoretical basis for the therapy of NSCLC.

Circ_0025033 promotes the progression of ovarian cancer by activating the expression of LSM4 via targeting miR-184

BACKGROUND

Ovarian cancer (OC) is the leading disorder to threaten women's lives. Numerous circular RNAs (circRNAs) were identified in cancers with dysregulation and involved in the pathogenesis of cancer. This study investigated the function and regulatory mechanism of circ_0025033 in OC development, aiming to provide a potential strategy for OC treatment.

METHODS

For expression analysis, the expression levels of circ_0025033, LSM4 mRNA and miR-184 were detected by quantitative real-time polymerase chain reaction (qRT-PCR), and the protein level of LSM4 expression was detected by western blot. For functional analysis, the capacities of colony formation, migration/invasion and glycolysis metabolism were assessed by colony formation assay, transwell assay and the levels of glucose consumption and lactate production. The interaction between miR-184 and circ_0025033 or LSM4 was predicted by the bioinformatics tool and validated by dual-luciferase reporter assay. Xenograft models were established to determine the role of circ_0025033 in vivo.

RESULTS

The expression of circ_0025033 and LSM4 was promoted in OC tissues and cells. Circ_0025033 knockdown or LSM4 knockdown blocked the ability of colony formation, migration/invasion and glycolysis metabolism in OC cells. In mechanism, circ_0025033 functioned as a "competing endogenous RNA (ceRNA)" to modulate LSM4 expression by targeting miR-184. LSM4 overexpression recovered the inhibitory effects on colony formation, migration/invasion and glycolysis metabolism caused by circ_0025033 knockdown. Moreover, circ_0025033 knockdown also inhibited tumor growth in vivo by regulating LSM4 and targeting miR-184.

CONCLUSION

Circ_0025033 promotes the progression of OC by regulating LSM4 expression via targeting miR-184, which provided a new strategy to treat OC.

CircHIPK3 Promotes Thyroid Cancer Tumorigenesis and Invasion through the Mirna-338-3p/RAB23 Axis

Objective：Thyroid cancer is a common type of endocrine malignancy, and its incidence has been steadily increasing in many regions of the world. Numerous studies have found that the circRNAs in various cancer types are aberrantly expressed, which could be potential biological diagnostic markers and therapeutic targets. The purpose of this study was to investigate the role of circHIPK3 in the development and progression of thyroid cancer and its mechanism. Subject and Methods：qRT-PCR was used to detect the relative expression levels of circHIPK3 in thyroid cancer cell lines (K1, CAL-62, TPC1), human thyroid normal cells (Nthy-ori 3-1), 10 pairs of thyroid cancer tissues and corresponding adjacent normal tissues. CCK-8 and Transwell assays were used to detect the proliferation and metastasis ability of cells. The targeted relationships between circHIPK3-miR-338-3p and miR-338-3p-RAB23 were predicted by bioinformatics analysis and verified by dual-luciferase reporter assays. Results and Conclusion: The downregulation of circHIPK3 significantly reduced the migration, invasion and proliferation of thyroid carcinoma. Then, we demonstrated that circHIPK3 up-regulated the expression of its target gene RAB23 by sponging miR-338-3p to promote the tumorigenesis and invasiveness of thyroid cancer. This study is the first to find that circHIPK3 plays the role of oncogenetic circRNA in thyroid cancer, which may provide new insights into how circRNA affects the progression of thyroid cancer. Our study also showed that circHIPK3 could be a novel biomarker for thyroid cancer.

MicroRNA in Papillary Thyroid Carcinoma: A Systematic Review from 2018 to June 2020

Simple Summary

The most common form of endocrine cancer - papillary thyroid carcinoma, has an increasing incidence. Although this disease usually has an indolent behavior, there are cases when it can evolve more aggressively. It has been known for some time that it is possible to use microRNAs for the diagnosis, prognosis and even treatment monitoring of papillary thyroid cancer. The purpose of this study is to summarize the latest information provided by publications regarding the involvement of microRNAs in papillary thyroid cancer, underling the new clinical perspectives offered by these publications.

Abstract

The involvement of micro-ribonucleic acid (microRNAs) in metabolic pathways such as regulation, signal transduction, cell maintenance, and differentiation make them possible biomarkers and therapeutic targets. The purpose of this review is to summarize the information published in the last two and a half years about the involvement of microRNAs in papillary thyroid carcinoma (PTC). Another goal is to understand the perspective offered by the new findings. Main microRNA features such as origin, regulation, targeted genes, and metabolic pathways will be presented in this paper. We interrogated the PubMed database using several keywords: “microRNA” + “thyroid” + “papillary” + “carcinoma”. After applying search filters and inclusion criteria, a selection of 137 articles published between January 2018–June 2020 was made. Data regarding microRNA, metabolic pathways, gene/protein, and study utility were selected and included in the table and later discussed regarding the matter at hand. We found that most microRNAs regularly expressed in the normal thyroid gland are downregulated in PTC, indicating an important tumor-suppressor action by those microRNAs. Moreover, we showed that one gene can be targeted by several microRNAs and have nominally described these interactions. We have revealed which microRNAs can target several genes at once.

Circular RNAs: New players in thyroid cancer

The prevalence of thyroid cancer the most frequent endocrine malignancy, is rapidly increasing. Most of thyroid cancers are relatively indolent, however, some cases still possess a risk of developing into lethal types of thyroid cancer. Regarding its multistep tumorigenesis, the determination of the underlying mechanisms is a vital issue for thyroid cancer therapy. Circular RNAs (circRNAs) are a type of non-coding RNAs with a closed loop structure. Numerous circRNAs have been identified in cancerous tissues. Mounting data recommends that the biological activities of circRNAs, such as serving as microRNA or ceRNAs sponges, interacting with proteins, modulating gene translation and transcription, suggesting that circRNAs will be potential targets as well as agents for the prognosis and diagnosis of diseases, including cancer. Given that circular RNAs acts as oncogenes or tumor suppressors in the thyroid cancer. Several studies documented that circular RNAs via microRNA and protein sponges could regulate a sequences of cellular and molecular mechanisms e.g., apoptosis, angiogenesis, tumor growth, and invasion that are involved in thyroid cancer pathogenesis. Herein, we summarized the role of circular RNAs as therapeutic and diagnostic biomarkers in the thyroid cancer. Moreover, we highlighted the role of these molecules in the pathogenesis of various cancers.

Genomics Score Based on Genome-Wide Network Analysis for Prediction of Survival in Gastric Cancer: A Novel Prognostic Signature

Purpose

Gastric cancer (GC) is a product of multiple genetic abnormalities, including genetic and epigenetic modifications. This study aimed to integrate various biomolecules, such as miRNAs, mRNA, and DNA methylation, into a genome-wide network and develop a nomogram for predicting the overall survival (OS) of GC.

Materials and Methods

A total of 329 GC cases, as a training cohort with a random of 150 examples included as a validation cohort, were screened from The Cancer Genome Atlas database. A genome-wide network was constructed based on a combination of univariate Cox regression and least absolute shrinkage and selection operator analyses, and a nomogram was established to predict 1-, 3-, and 5-year OS in the training cohort. The nomogram was then assessed in terms of calibration, discrimination, and clinical usefulness in the validation cohort. Afterward, in order to confirm the superiority of the whole gene network model and further reduce the biomarkers for the improvement of clinical usefulness, we also constructed eight other models according to the different combinations of miRNAs, mRNA, and DNA methylation sites and made corresponding comparisons. Finally, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were also performed to describe the function of this genome-wide network.

Results

A multivariate analysis revealed a novel prognostic factor, a genomics score (GS) comprising seven miRNAs, eight mRNA, and 19 DNA methylation sites. In the validation cohort, comparing to patients with low GS, high-GS patients (HR, 12.886; P < 0.001) were significantly associated with increased all-cause mortality. Furthermore, after stratification of the TNM stage (I, II, III, and IV), there were significant differences revealed in the survival rates between the high-GS and low-GS groups as well (P < 0.001). The 1-, 3-, and 5-year C-index of whole genomics-based nomogram were 0.868, 0.895, and 0.928, respectively. The other models have comparable or relatively poor comprehensive performance, while they had fewer biomarkers. Besides that, DAVID 6.8 further revealed multiple molecules and pathways related to the genome-wide network, such as cytomembranes, cell cycle, and adipocytokine signaling.

Conclusion

We successfully developed a GS based on genome-wide network, which may represent a novel prognostic factor for GC. A combination of GS and TNM staging provides additional precision in stratifying patients with different OS prognoses, constituting a more comprehensive sub-typing system. This could potentially play an important role in future clinical practice.

Circ_LDLR promoted the development of papillary thyroid carcinoma via regulating miR-195-5p/LIPH axis

Background

Emerging studies have demonstrated that circular RNAs (circRNAs) are key regulators for tumorigenesis in cancers, including papillary thyroid carcinoma (PTC). In this study, we aimed to explore the effects of circ_LDLR on PTC.

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to determine the levels of circ_LDLR, miR-195-5p and lipase H (LIPH). RNase R digestion assay and Actinomycin D assay were utilized to analyze the characteristics of circ_LDLR. Colony formation assay and 3-(4,5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay were conducted to evaluate cell proliferation. Western blot assay was used for the determination of protein levels. Flow cytometry analysis was applied to determine cell apoptosis. Transwell assay was performed to determine cell migration and invasion. Dual-luciferase reporter assay was used to verify the associations among circ_LDLR, miR-195-5p and LIPH. The murine xenograft model was constructed to explore the roles of circ_LDLR in vivo.

Results

Compared to normal tissues and cells, circ_LDLR was upregulated in PTC tissues and cells. Silencing of circ_LDLR suppressed PTC cell colony formation, proliferation, migration and invasion and promoted apoptosis in vitro and hampered tumor growth in vivo. For mechanism investigation, circ_LDLR could regulate LIPH expression via sponging miR-195-5p. Moreover, miR-195-5p inhibition restored the effects of circ_LDLR knockdown on the malignant behaviors of PTC cells. MiR-195-5p overexpression inhibited PTC cell colony formation, proliferation, migration and invasion and facilitated apoptosis by targeting LIPH.

Conclusion

Circ_LDLR knockdown decelerated PTC progression by regulating miR-195-5p/LIPH axis, which might provide a novel therapeutic target for PTC.

Circular RNA CircPRMT5 Accelerates Proliferation and Invasion of Papillary Thyroid Cancer Through Regulation of miR-30c/E2F3 Axis

Background

The role of circular RNA (circRNA) in papillary thyroid cancer (PTC) is largely unknown. This study aims to determine the function and mechanism of circPRMT5 in the regulation of PTC development.

Methods

PTC tissues and cell lines were used to determine circPRMT5 expression via quantitative real-time polymerase chain reaction. Small interfering RNA (siRNA) was utilized to knock down circPRMT5. Proliferation was analyzed through CCK8 and colony formation assays. Transwell assay was performed to determine cell migration and invasion. Luciferase assay and RIP assay were carried out to analyze the interaction between circPRMT5 and miR-30c.

Results

CircPRMT5 expression was upregulated in PTC tissues and cell lines. And circPRMT5 level was positively linked with advanced stage and lymph node metastasis. CircPRMT5 knockdown inhibited proliferation, migration and invasion while inducing apoptosis. CircPRMT5 worked as a competing endogenous RNA for miR-30c. By inhibiting miR-30c, circPRMT5 promoted the expression of E2F3.

Conclusion

Our findings demonstrate that circPRMT5 acts as an oncogenic circRNA to promote PTC progression via regulating miR-30c/E2F3 axis.

Circular RNA Circ_0025033 Promotes the Evolvement of Ovarian Cancer Through the Regulation of miR-330-5p/KLK4 Axis

Background

Circular RNAs (circRNAs) are significant molecular targets in various types of human cancers. The functional mechanism of circRNA_0025033 (circ_0025033) in ovarian cancer (OC) was discussed in the current report.

Methods

The quantitative real-time polymerase chain reaction (qRT-PCR) was used for determining the circ_0025033 and microRNA-330-5p (miR-330-5p) levels. Cell Counting Kit-8 (CCK-8) and transwell assays were separately exploited to analyze cell viability and migration/invasion. Cell apoptosis was assessed using flow cytometry. The protein levels of epithelial–mesenchymal transition (EMT)-related makers and kallikrein-related peptidase 4 (KLK4) were measured by Western blotting. The target combination was confirmed by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) and RNA pull-down assays. And the effect of circ_0025033 on OC in vivo was explored via xenograft tumor assay.

Results

Circ_0025033 was overexpressed in OC tissues and cells. Circ_0025033 knockdown inhibited OC cell viability, migration, invasion and EMT while expedited apoptosis. MiR-330-5p was a target of circ_0025033 and circ_0025033 regulated OC cellular behaviors by sequestering miR-330-5p. Moreover, miR-330-5p targeted KLK4 and circ_0025033 affected the KLK4 expression by sponging miR-330-5p. And miR-330-5p functioned as a tumor inhibitor in OC via targeting KLK4. In vivo, circ_0025033 promoted OC growth by the miR-330-5p/KLK4 axis.

Conclusion

This study demonstrated that circ_0025033 contributed to the progression of OC via the miR-330-5p/KLK4 axis and might be a candidate target in the identification and treatment of OC.

circFOXM1 promotes proliferation of non-small cell lung carcinoma cells by acting as a ceRNA to upregulate FAM83D

Background

Biological role and clinical significance of circular RNAs (circRNAs) remain largely unknown. Herein, we aimed to investigate biological function, molecular mechanism, and clinical significance of a circular RNA FOXM1 (circFOXM1) in non-small cell lung cancer (NSCLC).

Methods

Expression of circFOXM1 was measured in 48 paired samples of NSCLC by qRT-PCR. Functional roles of circFOXM1 on tumor cells were explored by in vitro and in vivo assays. Transcriptome sequencing was employed to screen the molecules involved in circFOXM1 regulatory network. RNA immunoprecipitation, luciferase analysis, RNA pull-down, and rescue assay were used to investigate potential mechanisms of circFOXM1.

Results

We found that circFOXM1 was significantly upregulated in NSCLC tissues, and its upregulation was positively correlated with advanced clinical stage and poor prognosis of NSCLC patients. Gain or loss-of-function assay showed that circFOXM1 promoted cell proliferation and cell cycle progression. In vivo assays showed that silencing circFOXM1 inhibited xenograft tumor growth. Mechanically, transcriptome sequencing data indicated that silencing circFOXM1 led to the downregulation of cell cycle-related mRNAs. RNA pull-down and dual-luciferase reporter assay suggested that circFOXM1 could bind to miR-614, and FAM83D was an essential gene involved in the circFOXM1/miR-614 regulatory network.

Conclusions

circFOXM1promotes NSCLC progression by interacting with miR-614 and thus inactivating the function of miR-614, which will further release the suppression of FAM83D. circFOXM1/miR-614/FAM83D regulatory network may serve as a potential therapeutic target for NSCLC patients.

A putative competing endogenous RNA network in cisplatin-resistant lung adenocarcinoma cells identifying potentially rewarding research targets

Lung adenocarcinoma (LUAD) is the most common type of non-small cell lung cancer and has a poor 5 year survival rate (<10%). Cisplatin is one of the most effective chemotherapeutic treatments for LUAD, even though it is of limited overall utility due to acquired drug resistance. To identify possible genetic targets for the mitigation of cisplatin resistance, gene expression data from cisplatin-resistant cell lines were integrated with patient information. Expression data for cisplatin-resistant and cisplatin-sensitive A549 cell lines were obtained from the Gene Expression Omnibus database, while LUAD patient data was obtained from The Cancer Genome Atlas (TCGA) database. Differentially expressed mRNAs (DEmRNAs), microRNAs (DEmiRNAs) and long non-coding RNAs (DElncRNAs) were identified between the cisplatin-sensitive and cisplatin-resistant cells. Using the TCGA patient data, 33 DEmRNAs associated with survival were identified. A total of 74 DElncRNAs co-expressed with the survival-associated DEmRNAs, and 11 DEmiRNAs that regulated the survival-associated DEmRNAs, were also identified. A competing endogenous RNA (ceRNA) network was constructed based on the aforementioned results, which included 17 survival-associated DEmRNAs, 9 DEmiRNAs and 16 DElncRNAs. This network revealed 8 ceRNA pathway axes possibly associated with cisplatin resistance in A549 cells. Specifically, the network suggested that the lncRNAs HOXD-AS2, LINC01123 and FIRRE may act as ceRNAs to increase cisplatin resistance in human LUAD cells. Therefore, it was speculated that these lncRNAs represent potentially rewarding research targets.

Biological Roles and Mechanisms of Circular RNA in Human Cancers

Circular RNA (circRNA) is an intriguing class of RNA with covalently closed-loop structure and is highly stable and conservative. As new members of the ncRNAs, the function, mechanism, potential diagnostic biomarker, and therapeutic target have raised increased attention. Most circRNAs are presented with characteristics of abundance, stability, conservatism, and often exhibiting tissue/developmental-stage-specific manner. Over 30,000 circRNAs have been identified with their unique structures to maintain stability more easily than linear RNAs. An increased numbers of circRNAs are dysregulated and involved in several biological processes of malignance, such as tumorigenesis, growth, invasion, metastasis, apoptosis, and vascularization. Emerging evidence suggests that circRNAs play important roles by acting as miRNA sponge or protein scaffolding, autophagy regulators, and interacting with RNA-binding protein (RBP), which may potentially serve as a novel promising biomarker for prevention, diagnosis and therapeutic target for treatment of human cancer with great significance either in scientific research or clinic arena. This review introduces concept, major features of circRNAs, and mainly describes the major biological functions and clinical relevance of circRNAs, as well as expressions and regulatory mechanisms in various types of human cancer, including pathogenesis, mode of action, potential target, signaling regulatory pathways, drug resistance, and therapeutic biomarkers. All of which provide evidence for the potential utilities of circRNAs in the diagnosis and treatment of cancer.

Circ_0058124 Upregulates MAPK1 Expression to Promote Proliferation, Metastasis and Metabolic Abilities in Thyroid Cancer Through Sponging miR-940

Background

Thyroid cancer (TC) is an endocrine disease, and its progression is regulated by many factors, including circular RNAs (circRNAs). However, as a new circRNA, the role of circ_0058124 in TC is worth further exploration.

Methods

The expression levels of circ_0058124, microRNA-940 (miR-940) and mitogen-activated protein kinase 1 (MAPK1) were assessed by quantitative polymerase chain reaction (q-PCR). The circular characteristic of circ_0058124 was identified by oligo (dT)₁₈ primers, Ribonuclease R (RNase R) and Actinomycin D (ActD), and its localization was determined by nuclear-cytoplasmic separation assay. Also, cell proliferation was detected by colony formation assay, and cell migration and invasion were assessed by transwell assay. Further, Seahorse XF Extracellular Flux Analyzer was used to measure the oxygen consumption rate (OCR) of cells. Besides, dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays were used to identify the mechanism of circ_0058124. Western blot (WB) analysis was used to test the MAPK1 protein level. In addition, mice xenograft models were constructed to test the effect of circ_0058124 on TC tumor growth in vivo.

Results

Circ_0058124 was highly expressed in TC and is a stable cyclic transcript, mainly located in the cytoplasm. Circ_0058124 knockdown suppressed proliferation, migration, invasion and metabolic abilities in TC cells. MiR-940 could be absorbed by circ_0058124, and the inhibition effect of its overexpression on TC progression could be reversed by overexpressed-circ_0058124. MAPK1 was a target of miR-940, and the suppression effect of its silencing on TC progression could be inverted by miR-940 inhibitor. Besides, MAPK1 expression was regulated by circ_0058124 and miR-940. Interference of circ_0058124 also reduced TC tumor growth in vivo.

Conclusion

Circ_0058124 might play a carcinogenic role in TC progression by regulating the miR-940/MAPK1 axis, which might provide a new idea for the treatment of TC.

Hsa_circ_0039411 promotes tumorigenesis and progression of papillary thyroid cancer by miR-1179/ABCA9 and miR-1205/MTA1 signaling pathways

Papillary thyroid cancer (PTC) is a common malignancy in endocrine system worldwide. Increasing evidence has shown that dysregulation of circular RNAs (circRNAs) could contribute to PTC tumorigenesis. The aims of this project are to investigate the potential role and molecular mechanism of hsa_circ_0039411 in PTC. In the project, RT-qPCR was performed to measure the expression profile of hsa_circ_0039411 in PTC tissues and cells. Cell counting kit-8, clonogenic, flow cytometric, and transwell experiments were used to identify the biological role of hsa_circ_0039411 on PTC cell progression. Bioinformatics methods, along with the dual-luciferase reporter test, was used to identify the potential mechanism of hsa_circ_0039411. Hsa_circ_0039411 was identified as enhanced in PTC tissues/cells. Gain-of-function experiments indicated that hsa_circ_0039411 facilitated PTC cell growth, migration, and invasion and inhibited cell apoptosis. Knockdown of hsa_circ_0039411 caused the opposite effects mentioned above. The mechanism exploration showed that hsa_circ_0039411 functioned as a sponge for miR-1179 and miR-1205 to elevate ATP-binding cassette transporter A9 (ABCA9) and metastasis-associated 1 (MTA1) expression at the post-transcriptional level, respectively. Further investigation confirmed that the functions of hsa_circ_0039411 are dependent on its modulation of ABCA9 and MTA1 in PTC cells. This study uncovered a mechanism of hsa_circ_0039411 in PTC, which might act as a novel therapeutic target for PTC.

Circular RNA Profiling Reveals Exosomal circ_0006156 as a Novel Biomarker in Papillary Thyroid Cancer

Circular RNAs (circRNAs) are a class of noncoding RNAs that are broadly expressed in various biological cells and function in regulating gene expression. However, the molecular mechanisms that link circRNAs with progression of papillary thyroid carcinoma (PTC) are not well understood. In the present study, the function of circ_0006156 (circFNDC3B) was investigated in human PTC cells. First, we detected the expression of circFNDC3B in PTC tissues and PTC cell lines by RT-PCR. A luciferase reporter assay and AGO2-RNA immunoprecipitation (RIP) was used to confirm the relationship between circFNDC3B and microRNA (miR)-1178. PTC cells were stably transfected with small interfering RNA (siRNA) against circFNDC3B, and cell proliferation, migration, and invasion were detected to evaluate the effect of circFNDC3B in PTC, while tumorigenesis was assayed in nude mice. In this study, circFNDC3B was observed to be upregulated in PTC tissues and cell lines. Knockdown of circFNDC3B inhibited cell proliferation and promoted cell apoptosis in PTC cells. Bioinformatics analysis predicted that there is a circFNDC3B/miR-1178/Toll-like receptor 4 (TLR4) axis in PTC. The dual-luciferase reporter system validated the direct interaction of circFNDC3B, miR-1178, and TLR4. Furthermore, circFNDC3B facilitates PTC progression in vivo. Importantly, we demonstrated that circFNDC3B was upregulated in serum exosomes from PTC patients. In summary, our study demonstrated that circFNDC3B modulates PTC progression through the miR-1178/TLR4 pathway. Our findings indicated that circFNDC3B may serve as a promising therapeutic target for the treatment of PTC patients.

Advances on circRNAs Contribute to Carcinogenesis and Progression in Papillary Thyroid Carcinoma

In view of the highly increased prevalence of papillary thyroid carcinoma (PTC) year by year, it is of great importance to explore new molecular targets for anticancer strategies. Emerging evidence indicates that circular RNAs (circRNAs), characterized by a closed-loop structure and high stability, play important roles in tumorigenesis and development of human cancer by regulating multiple complex biological processes, such as cellular proliferation, metastasis, and metabolism. A comprehensive understanding of the roles of circRNAs will facilitate the development of promising future therapeutic strategies for treating cancers, including PTC. In this paper, we review the profile of circRNA in PTC, its regulatory roles, and the pathological mechanism as well as their related clinical significance. In addition, challenges of this specific field are discussed.

miR-1231 Is Downregulated in Prostate Cancer with Prognostic and Functional Implications

BACKGROUND

Our study investigated the expression levels of miR-1231 in prostate cancer tissues and cell lines and explored its potential prognostic significance as well as its functional effects on prostate cancer cells.

METHODS

miR-1231 expression levels were detected in prostate cancer tissues and prostate cancer cell lines using qRT-PCR. The prognostic significance of miR-1231 in prostate cancer was assessed using the Kaplan-Meier curve and Cox regression analyses. Evaluation of the impact of ectopic expression or inhibition of miR-1231 on aggressive tumor behavior (cellular proliferation, migration, and invasion) of prostate cancer cell lines involved the CCK-8 and Transwell assays.

RESULTS

miR-1231 expression was downregulated in both prostate cancer tissues and cell lines. Downregulation of miR-1231 was significantly associated with lymph node metastasis, higher TNM stage, higher clinical stage, and shorter overall survival. The expression of miR-1231 was predicted as a prognostic factor for prostate cancer patients. Additionally, we found overexpression of miR-1231 suppressed proliferation, migration, and invasion of prostate cancer cell linesin vitro. EGFR was a direct target of miR-1231.

CONCLUSION

Taken together, our results indicate that miR-1231 expression plays a tumor-suppressive role in prostate cancer. It is downregulated in prostate cancer and may suppress prostate cancer cell proliferation, migration, and invasion by targeting EGFR, and it may be a prognostic biomarker and potential therapeutic strategy for prostate cancer treatment in the future.

Circ-MTO1 correlates with favorable prognosis and inhibits cell proliferation, invasion as well as miR-17-5p expression in prostate cancer

BACKGROUND

This study aimed to investigate circular RNA-mitochondrial tRNA translation optimization 1 (circ-MTO1) expression in tumor tissue and its correlation with clinical characteristics and survival profiles, as well as its effect on cancer cell functions in prostate cancer.

METHODS

A total of 298 primary prostate cancer patients were included. Reverse transcription-quantitative polymerase chain reaction was conducted to evaluate circ-MTO1 expression in tumor tissue and paired adjacent tissue. Disease-free survival (DFS) and overall survival (OS) were recorded. In in vitro experiment, prostate cancer cells were transfected with circ-MTO1 over-expression and negative-control over-expression plasmids. Then cell proliferation, cell invasion and miR-630 as well as miR-17-5p expressions in prostate cancer cells were detected.

RESULTS

Circular RNA-mitochondrial tRNA translation optimization 1 expression was downregulated in tumor tissue compared with paired adjacent tissue (P < .001) in patients with prostate cancer. Circ-MTO1 high expression in tumor tissue was correlated with decreased pathological T stage (P = .001) as well as lower pathological N stage (P = .020). As for survival profiles, the DFS (P = .006) and OS (P = .018) were both longer in patients who had circ-MTO1 high expression compared with patients who had circ-MTO1 low expression. In addition, circ-MTO1 high expression independently predicted favorable DFS and OS. Besides, further in vitro experiments illustrated that circ-MTO1 inhibited proliferation (P < .05) and invasion (P < .05) as well as downregulated miR-17-5p expression in prostate cancer cells (P < .05).

CONCLUSION

Circ-MTO1 correlates with decreased pathological T/N stage and favorable survival profiles, and it also inhibits cell proliferation, invasion as well as miR-17-5p expression in prostate cancer.