Therapeutic Potential of Circular RNAs in Osteosarcoma

CircBBS9 accelerates the malignant progression of osteosarcoma through sponging miR-485-3p/HMGB1 axis

BACKGROUND

Osteosarcoma (OS) is a leading malignant tumor reported with high mortality and morbidity. Dysexpression of CircBBS9 has been reported to exhibit a critical functional role in various diseases. However, the underlying molecular mechanisms of CircBBS9 in osteosarcoma are poorly characterized.

METHODS

The present study aims to investigate the impacts of CircBBS9 on the progression of osteosarcoma.

RESULTS

The findings of the study demonstrated the up-regulated expression of CircBBS9 in osteosarcoma. The Actinomycin D and RNase R treatment experiments confirmed that circBBS9 is indeed a circRNA. In addition, the knockdown of circBBS9 negatively impacted the migration, proliferation and invasion of osteosarcoma cells. Further investigations illustrated that circBBS9 controlled miR-485-3p and miR-485-3p might directly interact with HMGB1. miR-485-3p had a negative regulatory role in HMGB1's gene expression. Through rescue assays, it was verified that CircBBS9 promoted osteosarcoma progression through the miR-485-3p/HMGB1 axis. Finally, circBBS9 knockdown attenuated the in-vivo growth of osteosarcoma.

CONCLUSIONS

Conclusively, our study is the first time to examine the possible functional mechanism and regulation roles of CircBBS9 in osteosarcoma. The findings explained that CircBBS9 promoted the malignant osteosarcoma's progression by sponging miR-485-3p/HMGB1 and proposed CircBBS9 as a prognostic biomarker and therapeutic candidate for osteosarcoma patients.

Research progress on the role of lncRNA, circular RNA, and microRNA networks in regulating ferroptosis in osteosarcoma

Noncoding RNAs (ncRNAs) do not participate in protein-coding. Ferroptosis is a newly discovered form of cell death mediated by reactive oxygen species and lipid peroxidation. Recent studies have shown that ncRNAs such as microRNAs, long noncoding RNAs, circular RNAs, and ferroptosis are involved in the occurrence and development of osteosarcoma (OS). Studies have confirmed that ncRNAs participate in the development of OS by regulating the ferroptosis. However, systematic summary on this topic are still lacking. This review summarises the potential role of ncRNAs in the diagnosis, treatment, drug resistance, and prognosis of OS and the basis for diagnosing, preventing, and treating clinical OS and developing effective drugs. This review summarises the latest research progress on ncRNAs that regulate ferroptosis in OS, attempts to clarify the molecular mechanisms by which ncRNAs regulate ferroptosis in the pathogenesis of OS, and elaborates on the involvement of ferroptosis in OS from the perspective of ncRNAs.

Exploring non-coding RNA mechanisms in hepatocellular carcinoma: implications for therapy and prognosis

Hepatocellular carcinoma (HCC) is a significant contributor to cancer-related deaths in the world. The development and progression of HCC are closely correlated with the abnormal regulation of non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Important biological pathways in cancer biology, such as cell proliferation, death, and metastasis, are impacted by these ncRNAs, which modulate gene expression. The abnormal expression of non-coding RNAs in HCC raises the possibility that they could be applied as new biomarkers for diagnosis, prognosis, and treatment targets. Furthermore, by controlling the expression of cancer-related genes, miRNAs can function as either tumor suppressors or oncogenes. On the other hand, lncRNAs play a role in the advancement of cancer by interacting with other molecules within the cell, which, in turn, affects processes such as chromatin remodeling, transcription, and post-transcriptional processes. The importance of ncRNA-driven regulatory systems in HCC is being highlighted by current research, which sheds light on tumor behavior and therapy response. This research highlights the great potential of ncRNAs to improve patient outcomes in this difficult disease landscape by augmenting the present methods of HCC care through the use of precision medicine approaches.

Circ_UBAP2 exacerbates proliferation and metastasis of OS via targeting miR-665/miR-370-3p/HMGA1 axis

Circ_UBAP2 is extensively engaged in regulating the development of various malignancies, containing osteosarcoma (OS). However, its biological significance and function are not fully understood. In this study, we found that circ_UBAP2 and HMGA1 levels were up-regulated, and miR-370-3p and miR-665 expressions were decreased in osteosarcoma tissues. Inhibition of circ_UBAP2 or HMGA1 expression in OS cells, cell viability, invasion and migration abilitities were notably hindered, and cell apoptosis abilities were increased. Bioinformatics analysis predicted that miR-665 and miR-370-3p were the downstream targets of circ_UBAP2, and the dual luciferase experiment demonstrated the correlation between them. In addition, inhibition of miR-665 and miR-370-3p expression could significantly reverse the impact of knocking down circ_UBAP2 on OS cells. HMGA1 was discovered to become the downstream target of both miR-665 and miR-370-3p. It was shown that over-expression of miR-665 or miR-370-3p notably stimulated the cell growth, invasion, and migration of osteosarcoma cells, while hindered cell apoptosis. Nevertheless, this effect could be reversed by concurrent over-expression of HMGA1. Our data strongly prove that circ_UBAP2 makes a vital impact on promoting the proliferation, invasion as well as migration of osteosarcoma cells via down-regulating the level of miR-665 and miR-370-3p, and later up-regulating the level of HMGA1. In conclusion, circ_UBAP2 is upregulated in osteosarcoma, and it competitively adsorbs miR-370-3p and miR-665, resulting in up-regulation of HMGA1, thus promoting OS development.

Advancements in Understanding the Role of Circular RNA in Osteosarcoma

Osteosarcoma, the most prevalent primary malignant bone tumor and the third most frequent cancer in children and adolescents worldwide, still poses a significant therapeutic challenge. Even though combined chemotherapy and surgical resection have improved survival rates up to 60%, the prognosis for most patients with metastatic osteosarcoma continues to be dismal. The specific pathogenesis and key regulators of tumor invasion and metastasis remain largely elusive. Circular RNAs (circRNAs), novel endogenous non-coding RNA molecules that form covalently closed continuous loops through splicing, play a crucial role in the development, progression, clinical diagnosis, and treatment of various diseases. Recently, an escalating number of circular structures have been identified in osteosarcoma. Understanding their role in osteosarcoma is advantageous for early detection, diagnosis, and treatment of this disease. The primary function of circRNA involves its unique ability to bind specifically to miRNA, although their biological functions also extend to interacting with proteins, regulating gene transcription, and serving as translation templates. In this review, we explore the mechanisms and clinical applications of circRNAs in the pathogenesis and progression of osteosarcoma, with a particular emphasis on the regulatory mechanisms and functions of circRNAs as miRNA sponges in osteosarcoma development.

Interactions between circRNAs and miR-141 in Cancer: From Pathogenesis to Diagnosis and Therapy

The function of non-coding RNAs (ncRNAs) in the pathogenesis and development of cancer is indisputable. Molecular mechanisms underlying carcinogenesis involve the aberrant expression of ncRNAs, including circular RNAs (circRNAs), and microRNAs (miRNAs). CircRNAs are a class of single-stranded, covalently closed RNAs responsible for maintaining cellular homeostasis through their diverse functions. As a part of the competing endogenous RNA (ceRNAs) network, they play a central role in the regulation of accessibility of miRNAs to their mRNA targets. The interplay between these molecular players is based on the primary role of circRNAs that act as miRNAs sponges, and the circRNA/miRNA imbalance plays a central role in different pathologies including cancer. Herein, we present the latest state of knowledge about interactions between circRNAs and miR-141, a well-known member of the miR-200 family, in malignant transformation, with emphasis on the biological role of circRNA/miR-141/mRNA networks as a future target for novel anti-cancer therapies.

The emerging roles and potential applications of circular RNAs in ovarian cancer: a comprehensive review

Ovarian cancer (OC) is among the most common human malignancies and the first cause of deaths among gynecologic cancers. Early diagnosis can help improving prognosis in those patients, and accordingly exploring novel molecular mechanisms may lead to find therapeutic targets. Circular RNAs (circRNAs) comprise a group of non-coding RNAs in multicellular organisms, which are identified with characteristic circular structure. CircRNAs have been found with substantial functions in regulating gene expression through interacting with RNA-binding proteins, targeting microRNAs, and transcriptional regulation. They have been found to be involved in regulating several critical processes such as cell growth, and death, organ development, signal transduction, and tumorigenesis. Accordingly, circRNAs have been implicated in a number of human diseases including malignancies. They are particularly reported to contribute to several hallmarks of cancer leading to cancer development and progression, although a number also are described with tumor-suppressor function. In OC, circRNAs are linked to regulation of cell growth, invasiveness, metastasis, angiogenesis, and chemoresistance. Notably, clinical studies also have shown potentials in diagnosis, prediction of prognosis, and therapeutic targets for OC. In this review, I have an overview to the putative mechanisms, and functions of circRNAs in regulating OC pathogenesis in addition to their clinical potentials.

The circRNA circADAMTS6 promotes progression of ESCC and correlates with prognosis

Circular RNAs (circRNAs) are a type of noncoding RNA, which play a vital role in the occurrence and development of esophageal squamous cell carcinoma (ESCC). While the role of novel circADAMTS6 in ESCC remains unknown. We assessed circADAMTS6 expression in ESCC tissues and cells, and the relationship between circADAMTS6 expression and overall survival of ESCC patients. Functional experiments in vitro and xenograft in vivo assay were applied to explore the functions and mechanisms of circADAMTS6 in ESCC. Results found that up-regulation of circADAMTS6 was associated with poor overall survival and may acted as an independent risk factor for ESCC prognosis. Knockdown of circADAMTS6 significantly inhibited the proliferation, migration and invasion of ESCC cells and growth of xenograft tumors in vivo. Induced AGR2 expression was able to rescue the loss of function induced by si-circADAMTS6 in KYSE150 cell. CircADAMTS6 may acts as oncogene by activating AGR2 and the Hippo signaling pathway coactivator YAP in ESCC.

Circular RNAs: Functions and mechanisms in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant epithelial tumor of the nasopharyngeal mucosa with a high incidence rate in southern China and Southeast Asia and an evident ethnic and geographical distribution. Circular RNAs (circRNAs) are single-stranded noncoding RNAs with covalent, closed-loop structures. They are characterized by high stability and abundance, are evolutionarily conserved, and exhibit tissue/developmental stage specificity. Previous studies have shown that circRNAs are associated with the occurrence and development of various malignant tumors. However, the expression patterns and clinical significance of circRNAs in NPC remain ambiguous. Hence, the present review focuses on the biogenesis and regulation of circRNAs, and the functional roles of abnormally expressed circRNAs in NPC. In addition, the current review discusses the possibility of utilizing circRNAs as potential clinical biomarkers for the diagnosis and prognosis of NPC.

Clinicopathologic significance and prognostic value of circRNAs in osteosarcoma: a systematic review and meta-analysis

Abstract

Background

Osteosarcoma is the most prevalent malignant osseous sarcoma in children and adolescents, whose prognosis is still relatively poor nowadays. Recent studies have shown the critical function and potential clinical applications of circular RNAs (circRNAs) in osteosarcoma. Our review aimed to perform an updated meta-analysis to explore their clinicopathologic significance and prognostic value.

Methods

The structured literature was conducted via eight electronic databases and four gray literature sources until 20 Feb 2021 to identify eligible studies. The data was extracted directly from the articles or reconstructed based on Kaplan-Meier curves. The Newcastle-Ottawa Scale (NOS) tool was used to assess study quality. The clinicopathologic significance of circRNAs was measured through odds ratios (ORs) and their 95% confidence intervals (CIs), while the prognostic value was evaluated through hazard ratios (HRs) and their 95% CIs of overall survival (OS) and disease-free survival (DFS). Heterogeneity and publication bias were assessed. Sensitivity analyses were conducted. Subgroup analyses were performed according to study characteristics. An additional analysis was performed to investigate the relation between circ_0002052 and osteosarcoma.

Results

Fifty-two studies were identified, in which 38 on clinicopathologic features and 36 on survival prognosis were included in quantitative analysis. The overall study quality was moderate with a median NOS score of 5.5 stars (range 3 to 8). For clinicopathologic features, dysregulated circRNAs were related to larger tumor size (OR 2.122, 95%CI 1.418–3.175), advanced clinical stage (OR 2.847, 95%CI 2.059–3.935), and present of metastasis (OR 2.630, 95%CI 1.583–4.371). For chemotherapy, dysregulated circRNAs suggest a better response (OR 0.443, 95%CI 0.231–0.849), but a higher probability of resistance (OR 9.343, 95%CI 5.352–16.309). For survival prognosis, dysregulated circRNAs were significantly correlated with poor OS (HR 2.437, 95%CI 2.224–2.670) and DFS (HR 2.125, 95%CI 1.621–2.786). The results did not show differences among subgroups. Higher circ_0002052 expression showed a relation with poor OS (HR 3.197, 95%CI 2.054–4.976).

Conclusions

Our review demonstrated that abnormally expressed circRNAs have a relation with advanced clinicopathologic features and better response, but a higher probability of resistance and poor survival prognosis in osteosarcoma patients. However, more studies are encouraged to provide more robust evidence to translate circRNAs into clinical practice.

Trial registration

PROSPERO ID: CRD42021235031

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02568-2.

Hsa_circ_0088212-mediated miR-520 h/APOA1 axis inhibits osteosarcoma progression

BACKGROUND

It has been known for decades that circRNAs are deregulated in cancer. Here, we characterized the role and underlying mechanism of circ_0088212 in osteosarcoma.

METHODS

The expression levels of circ_0088212, miR-520 h, and APOA1 were determined by RT-qPCR. RNase R digestion was performed to verify the circular structure of circ_0088212. CCK8 and transwell invasion assays were conducted to examine the in vitro malignancy of osteosarcoma. Caspase-3 activity was also measured. An in vivo model of osteosarcoma was constructed to examine the in vivo effect of circ_0088212 on osteosarcoma. Luciferase reporter, RNA RIP, and RNA pull-down assays were performed to verify the interaction between miR-520 h and APOA1 or circ_0088212.

RESULTS

Circ_0088212 and APOA1 were expressed at low levels in osteosarcoma tissues and cells, while miR-520 h was highly expressed. Overexpression of circ_0088212 was found to inhibit the in vitro and in vivo growth of osteosarcoma. Mechanistically, miR-520 h was the target of circ_0088212 and APOA1 was the target of miR-520 h. Circ_0088212 downregulated miR-520 h expression, while miR-520 h overexpression abolished the inhibitory effect of circ_0088212 on osteosarcoma cell proliferation and migration. Furthermore, miR-520 h overexpression led to reduced APOA1 expression, while APOA1 overexpression counteracted the oncogenic effect of miR-520 h in osteosarcoma cells.

CONCLUSION

Our findings demonstrated that circ_0088212 might exert a tumor-suppressive activity in osteosarcoma by sponging and sequestering miR-520 h away from APOA1. This suggests that the circ_0088212/miR-520 h/APOA1 axis may be a promising therapeutic target for osteosarcoma intervention.

The circular RNA circCRIM1 inhibits osteosarcoma progression through sponging miR-513

Numerous studies have suggested that the abnormal expression of circular RNAs plays an essential role in the pathological progression of numerous tumors. Nonetheless, the functions and underlying mechanisms of the circular RNA circCRIM1 in osteosarcoma (OS) are still not fully understood. In this study, 47 classes of OS tissues and adjoining normal tissues were obtained from patients. Real-time PCR was employed to measure circCRIM1 expression levels in both OS tissues and cell lines. The proliferation, migration, and invasion ability in OS cell lines were measured by MTT assays, EDU assays, transwell migration experiments, and transwell invasion assays. The results demonstrated that the expression of circCRIM1 was notably decreased both in OS tissues and cell lines. Depressed circCRIM1 expression was correlated with lymph node metastasis, advanced FIGO stage, and low overall survival of OS patients. In addition, the results indicated that circCRIM1 could decrease the migration, invasion, and growth of OS cells. Further mechanistic studies indicated that circCRIM1 served as a competing endogenous RNA (ceRNA) of miR-513, leading to decreases in the proliferation, migration, and invasion of OS cells. Taken together, our data uncovered a significant role of the circCRIM1/miR-513 pathway in the proliferation, migration, and invasion of OS cell lines and suggested that circCRIM1 may serve as a possible therapeutic target for OS treatment.

Circular RNAs in Hepatocellular Carcinoma: Emerging Functions to Clinical Significances

Hepatocellular carcinoma (HCC) is the most common primary cancer of the liver and carries high morbidity and mortality. Diagnosing HCC at an early stage is challenging. Therefore, finding new, highly sensitive and specific diagnostic biomarkers for the diagnosis and prognosis of HCC patients is extremely important. Circular RNAs (circRNAs) are a class of non-coding RNAs with covalently closed loop structures. They are characterized by remarkable stability, long half-life, abundance and evolutionary conservation. Recent studies have shown that many circRNAs are expressed aberrantly in HCC tissues and have important regulatory roles during the development and progression of HCC. Hence, circRNAs are promising biomarkers for the diagnosis and prognosis of HCC. This review: (i) summarizes the biogenesis, categories, and functions of circRNAs; (ii) focuses on current progress of dysregulated expression of circRNAs in HCC with regard to regulation of the tumor hallmarks, “stemness” of cancer cells, and immunotherapy; (iii) highlights circRNAs as potential biomarkers and therapeutic targets for HCC; and (iv) discusses some of the challenges, questions and future perspectives of circRNAs research in HCC.

Blocking circ-CNST suppresses malignant behaviors of osteosarcoma cells and inhibits glycolysis through circ-CNST-miR-578-LDHA/PDK1 ceRNA networks

Background

CircRNA CNST (circ-CNST) is a newly identified biomarker for prognosis of osteosarcoma (OS). However, its role in OS progression remains to be well documented.

Methods

Expression of circ-CNST, microRNA (miR)-578, lactate dehydrogenase A (LDHA), and pyruvate dehydrogenase kinase 1 (PDK1) was detected by quantitative real-time polymerase chain reaction and Western blotting. The physical interaction was confirmed by dual-luciferase reporter assay. Cell behaviors and glycolysis were measured by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay, colony formation assay, flow cytometry, transwell assays, xenograft experiment, and commercial kits.

Results

Circ-CNST was upregulated in human OS tissues and cells, accompanied with downregulation of miR-578 and upregulation of LDHA and PDK1. There were negative correlations between miR-578 expression and circ-CNST or LDHA/PDK1 in OS tissues. Moreover, high circ-CNST/LDHA/PDK1 or low miR-578 might predict shorter overall survival, advanced TNM stages, and lymph node metastasis. Physically, miR-578 was targeted by circ-CNST, and miR-578 could target LDHA/PDK1. Functionally, blocking circ-CNST and restoring miR-578 enhanced apoptosis rate and suppressed cell proliferation, colony formation, migration, and invasion in 143B and U2OS cells, accompanied with decreased glucose consumption, lactate production, and adenosine triphosphate (ATP)/adenosine diphosphate (ADP) ratio. Furthermore, in vivo growth of U2OS cells was retarded by silencing circ-CNST. Depletion of miR-578 could counteract the suppressive role of circ-CNST deficiency in 143B and U2OS cells, and restoring LDHA or PDK1 partially reversed the role of miR-578 inhibition as well.

Conclusion

Circ-CNST knockdown could antagonize malignant behaviors and glycolysis of OS cells by regulating miR-578-LDHA/PDK1 axes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02427-0.

Hsa_circ_0010220 regulates miR-198/Syntaxin 6 axis to promote osteosarcoma progression

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hsa_circ_0010220 expression is increased in osteosarcoma.

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hsa_circ_0010220 knockdown represses cell proliferation, migration and invasion.

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hsa_circ_0010220 regulates Syntaxin 6 via miR-198.

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hsa_circ_0010220 silence decreases xenograft tumor growth.

Background

Circular RNAs (circRNAs) are a class of endogenous RNAs that are involved in osteosarcoma progression. Hsa_circ_0010220 (circ_0010220) is a circRNA generated by gene Rho Guanine Nucleotide Exchange Factor 10 Like (ARHGEF10L) and is upregulated in osteosarcoma, but its functional role in osteosarcoma is limited studied. This study aimed to illustrate the regulatory mechanism underlying circ_0010220 in osteosarcoma.

Methods

51 paired tumor and normal tissues were obtained from osteosarcoma patients. circ_0010220, microRNA (miR)-198 and Syntaxin 6 (STX6) abundances were examined by quantitative reverse transcription polymerase chain reaction and western blot. Cell proliferation, cell cycle, apoptosis, migration and invasion were analyzed via Cell Counting Kits-8 (CCK-8), colony formation, flow cytometry and transwell analyses. Target relationship was verified via dual-luciferase reporter analysis, RNA immunoprecipitation and pull-down. The in vivo function was analyzed using a xenograft model.

Results

Circ_0010220 was elevated in osteosarcoma tissues and cells, and was related to the lower survival rate of osteosarcoma patients. Circ_0010220 knockdown inhibited cell proliferation, migration and invasion, but induced cell cycle arrest and apoptosis in vitro. Besides, circ_0010220 silence curbed the growth of xenograft osteosarcoma tumors in vivo. Mechanistic research revealed that miR-198 is a target of circ_0010220, and directly targets STX6. Moreover, circ_0010220 upregulated the expression of STX6 by sponging miR-198 to regulate cell proliferation, migration, invasion, cell cycle, and apoptosis.

Conclusion

Circ_0010220 contributes to osteosarcoma progression through mediating miR-198/STX6 axis, which might be a novel therapeutic target for osteosarcoma therapy.

CircRNA circ_0092314 Induces Epithelial-Mesenchymal Transition of Pancreatic Cancer Cells via Elevating the Expression of S100P by Sponging miR-671

Background

Circular RNAs (circRNAs) is a novel class of non-coding RNAs that regulate gene expression during cancer progression. Circ_0092314 is a newly discovered circRNA that was upregulated in pancreatic cancer (PAAD) tissues. However, the detailed functions and underlying mechanisms of circ_0092314 in PAAD cells remain unclear.

Methods

We first determined the expression of circ_0092314 in PAAD and normal tissues and further investigated the functional roles of circ_0092314 in regulating epithelial-mesenchymal transition (EMT) of PAAD cells. We also assessed the regulatory action of circ_0092314 on the microRNA-671 (miR-671) and its target S100P.

Results

Circ_0092314 was markedly upregulated in PAAD tissues and cells, and its overexpression was closely correlated with worse prognosis of PAAD patients. Functionally, circ_0092314 promotes proliferation, invasion and EMT in vitro and tumor growth in vivo. Mechanistically, we demonstrated that circ_0092314 directly binds to miR-671 and relieve its suppression of the downstream target S100P, which induces EMT and activates the AKT signaling pathway. The tumor-promoting effects caused by overexpression of circ_0092314 could be revered by re-expression of miR-671 in PAAD cells.

Conclusions

Overall, our study demonstrates that circ_0092314 exerts critical roles in promoting the EMT features of PAAD cells, and provides insight into how elevated expression of circ_0092314 might influence PAAD progression.

Analysis of Immune Gene Expression Subtypes Reveals Osteosarcoma Immune Heterogeneity

Background

Osteosarcoma (OS) patients have a poor response to immunotherapy due to the sheer complexity of the immune system and the nuances of the tumor-immune microenvironment. Methodology. To gain insights into the immune heterogeneity of OS, we identified robust clusters of patients based on the immune gene expression profiles of OS patients in the TARGET database and assessed their reproducibility in an independent cohort collected from the GEO database. The association of comprehensive molecular characterization with reproducible immune subtypes was accessed with ANOVA. Furthermore, we visualized the distribution of individual patients in a tree structure by the graph structure learning-based dimensionality reduction algorithm.

Results

We found that 87 OS samples can be divided into 5 immune subtypes, and each of them was associated with distinct clinical outcomes. The immune subtypes also demonstrated widely different patterns in tumor genetic aberrations, tumor-infiltrating, immune cell composition, and cytokine profiles. The immune landscape of OS uncovered the significant intracluster heterogeneity within each subtype and depicted a continuous immune spectrum across patients.

Conclusion

The established five immune subtypes in our study suggested immune heterogeneity in OS patients and may provide optimal individual immunotherapy for patients exhibiting OS.

Circ_0082182 promotes oncogenesis and metastasis of colorectal cancer in vitro and in vivo by sponging miR-411 and miR-1205 to activate the Wnt/β-catenin pathway

BACKGROUND

Circular RNAs (circRNAs) are a class of endogenous single-strand RNA transcripts with crucial regulation in human cancers. The objective of this study is to investigate the role of circ_0082182 in CRC and its specific functional mechanism.

METHODS

The quantitative real-time polymerase chain reaction (qRT-PCR) was performed to measure the levels of circ_0082182, microRNA-411 (miR-411) and microRNA-1205 (miR-1205). Cell proliferation was detected by Cell counting Kit-8 (CCK-8) and colony formation assays. Flow cytometry was used for determining cell cycle and cell apoptosis. Cell apoptosis was also assessed by caspase3 and caspase9 activities. Cell migration and invasion were examined using scratch assay and transwell assay. The interaction between circ_0082182 and miRNA was validated by the dual-luciferase reporter and biotinylated RNA pull-down assays. Wnt/β-catenin pathway and epithelial-mesenchymal transition (EMT)-associated proteins were quantified by Western blot. Xenograft model was established for the research of circ_0082182 in vivo.

RESULTS

Circ_0082182 was upregulated in CRC and could predict the poor prognosis of CRC patients. Functionally, circ_0082182 promoted CRC cell proliferation, cell cycle progression, and metastasis while inhibited apoptosis. Subsequently, circ_0082182 was shown to act as the sponges of miR-411 and miR-1205. MiR-411 and miR-1205 were identified as tumor inhibitors in CRC. Furthermore, circ_0082182 promoted the CRC progression via sponging miR-411 and miR-1205. Moreover, circ_0082182 facilitated the Wnt/β-catenin pathway and EMT process by targeting miR-411 and miR-1205. In vivo, circ_0082182 accelerated the CRC tumorigenesis and EMT process by activating the Wnt/β-catenin pathway by downregulating the expression of miR-411 or miR-1205.

CONCLUSION

This study showed that circ_0082182 functioned as an oncogene in the developing process of CRC by sponging miR-411 or miR-1205 to activate the Wnt/β-catenin pathway. Circ_0082182 might be a molecular target in the diagnosis and treatment of CRC.

Insights Into the Role of CircRNAs: Biogenesis, Characterization, Functional, and Clinical Impact in Human Malignancies

Circular RNAs (circRNAs) are an evolutionarily conserved novel class of non-coding endogenous RNAs (ncRNAs) found in the eukaryotic transcriptome, originally believed to be aberrant RNA splicing by-products with decreased functionality. However, recent advances in high-throughput genomic technology have allowed circRNAs to be characterized in detail and revealed their role in controlling various biological and molecular processes, the most essential being gene regulation. Because of the structural stability, high expression, availability of microRNA (miRNA) binding sites and tissue-specific expression, circRNAs have become hot topic of research in RNA biology. Compared to the linear RNA, circRNAs are produced differentially by backsplicing exons or lariat introns from a pre-messenger RNA (mRNA) forming a covalently closed loop structure missing 3′ poly-(A) tail or 5′ cap, rendering them immune to exonuclease-mediated degradation. Emerging research has identified multifaceted roles of circRNAs as miRNA and RNA binding protein (RBP) sponges and transcription, translation, and splicing event regulators. CircRNAs have been involved in many human illnesses, including cancer and neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease, due to their aberrant expression in different pathological conditions. The functional versatility exhibited by circRNAs enables them to serve as potential diagnostic or predictive biomarkers for various diseases. This review discusses the properties, characterization, profiling, and the diverse molecular mechanisms of circRNAs and their use as potential therapeutic targets in different human malignancies.

CircADAMTS6/miR-431-5p axis regulate interleukin-1β induced chondrocyte apoptosis

BACKGROUND

Growing evidence suggests that circular RNAs (circRNAs) are involved in the development of osteoarthritis (OA). The present study aimed to explore the CircADAMTS6/miR-431-5p axis with respect to regulating interleukin-1β (IL-1β) induced chondrocyte apoptosis.

METHODS

We first evaluated the differentially expressed circRNAs between normal chondrocytes and interleukin (IL)-1β-stimulated chondrocytes. Then, bioinformatic analysis was performed to identify the role and function of circADAMTS6. Small interfering RNA-expressing or overexpressing circADAMTS6 lentiviral vectors were used for transduction of chondrocytes. Annexin-V-fluorescein isothiocyanate (FITC) double staining was performed to measure the apoptotic rate of the chondrocytes in each group. Finally, a dual luciferase reporter assay was performed to identify the target relationship between circADAMTS6 and miR-431-5p.

RESULTS

After treatment with IL-1β, circADAMTS6 was down-regulated compared to the normal chondrocyte group. The overexpression of circADAMTS6 inhibited apoptosis in human chondrocytes, as indicated by annexin-V-FITC double staining. However, overexpression of miR-431-5p had the opposite effect. A dual luciferase reporter assay indicated that circADAMTS6 could directly binding with miR-431-5p.

CONCLUSIONS

Our findings demonstrate that the circADAMTS6/miR-431-5p axis comprises a new target for OA. Bioinformatic analysis suggested that circADAMTS6 acted as a sponge of miR-431-5p.

Down-regulation of circular RNA hsa_circ_0007534 suppresses cell growth by regulating miR-219a-5p/SOX5 axis in osteosarcoma

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The interaction between circ_0007534 and miR-219a-5p is confirmed for the first time.

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The interaction between miR-219a-5p and SOX5 is confirmed for the first time.

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Circ_0007534 knockdown inhibits the progression of osteosarcoma cells.

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Circ_0007534 regulates the growth of osteosarcoma cells through modulating miR-219a-5p/SOX5 axis.

Introduction

Circular RNA circ_0007534 and microRNA-219a (miR-219a-5p) were reported to be involved in osteosarcoma (OS) development. Osteosarcoma (OS) is one of the most common malignant bone tumors, which was more prone to occur in the metaphysis of long bones, including distal femur and proximal tibia. However, the detailed mechanisms were not fully clear. The purpose of this research was to reveal the functional mechanisms of circ_0007534 and miR-219a-5p in OS.

Methods

The levels of genes were determined by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay. Cell proliferation ability was detected by cell counting kit-8 (CCK-8) and colony formation assay. Cell migration and invasion abilities were measured using the transwell assay. Furthermore, the interaction between miR-219a-5p and circ_0007534 or SRY (sex-determining region Y)-box 5 (SOX5) was predicted by starbaseV3.0, and confirmed by the dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Besides, tumor xenograft experiment was performed to analyze the effect of circ_0007534 depletion on tumor growth in vivo.

Results

The levels of circ_0007534 and SOX5 were increased, while the miR-219a-5p level was decreased in OS tissues and cells. Circ_0007534 knockdown repressed the proliferation, colony formation, migration, and invasion in OS cells. Circ_0007534 targeted miR-219a-5p, and miR-219a-5p interacted with SOX5. Furthermore, circ_0007534 regulated the growth of OS cells through modulating the levels of miR-219a-5p and SOX5.

Conclusion

Our finding demonstrated that circ_0007534 knockdown suppressed the growth of OS cells via regulating miR-219a-5p/SOX5 axis, providing a potential target for OS treatment and diagnosis.

Flavonoid compound breviscapine suppresses human osteosarcoma Saos-2 progression property and induces apoptosis by regulating mitochondria-dependent pathway

This study was aimed to investigate the ability of a flavonoid compound breviscapine (BVP) to suppress growth and elicit apoptosis in human osteosarcoma (OS) Saos-2 cells. The cells were cultured in vitro and treated with three concentrations of BVP (80, 160, and 320 μg/ml). Moreover, C57 mice were injected with Saos-2 cells to establish a subcutaneous xenograft model, and they were subsequently treated with three doses of BVP via intraperitoneal injection. The viability of the cells was examined by the Cell Counting Kit-8 method. The apoptotic cells were assessed by flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. The tumor volume and weight were monitored from day 3 through day 21 after the last injection. The expression of bax, bcl-2, and cytochrome c (cyt c) mRNA was detected by a real-time polymerase chain reaction. The protein levels of bax, bcl-2, cyt c, caspase 3, and caspase 9 were evaluated by Western blot. The expression and distribution of bcl-2 and bax in tissues were detected by immunohistochemistry. Compared with the control group, BVP treatment inhibited cell proliferation and induced apoptosis of Saos-2 cells in vitro. Consistently, treatment of mice bearing transplanted tumors with BVP suppressed the growth of OS tumors and promoted cell apoptosis; it also reduced tumor volume and weight. Mechanistically, BVP-induced apoptosis was mediated by the mitochondria-dependent pathway, as evidenced by the increased expression of bax and cyt c and the decreased expression of bcl-2, as well as activation of caspase 9 and caspase 3 in vitro and in vitro. Collectively, BVP inhibits growth and promotes apoptosis of OS by activating the mitochondrial apoptosis pathway.

LINC00319 promotes osteosarcoma progression by regulating the miR-455-3p/NFIB axis

BACKGROUND

Numerous studies have shown that aberrant expression of long non-coding RNAs (lncRNAs) is associated with the development and metastasis of osteosarcoma (OS). However, the role and function of LINC00319 with respect to regulating OS progression is unknown. The present study aimed to reveal the function and related mechanism of LINC00319 in OS.

METHODS

The expression of LINC00319, miR-455-3p and nuclear factor IB (NFIB) in OS cells and tissues was determined using a reverse transcriptase-polymerase chain reaction (PCR). The sublocalization of LINC00319 was predicted by the lncATLAS database (http://lncatlas.crg.eu) and RNA fluorescence in situ hybridization (FISH) was further performed to detect the subcellular localization of LINC00319. LINC00319, miR-455-3p and NFIB target sites were predicted by StarBase (http://starbase.sysu.edu.cn/index.php) and validated using a dual luciferase reporter gene assay. We subsequently performed LINC00319 gain- and loss-of-function studies to define the role of LINC00319 in OS cell migration.

RESULTS

PCR results showed that lncRNA LINC00319 exhibited high expression in tumor cells and tissue. Moreover, LINC00319 was positioned in the cytoplasm, which was identified by FISH. Knockdown of lncRNA LINC00319/NFIB or overexpression of miR-455-3p blocked the migration of OS cells. In addition, the inhibitory effect of migration with the knockdown of lncRNA LINC00319 was partially blocked by administration of miR-455-3p inhibitor.

CONCLUSIONS

lncRNA LINC00319 may promote OS progression by regulating the miR-455-3p/NFIB axis, which probably serves as an innovative potential indicator of prognosis and a target of therapy for OS.