Circular RNA has_circ_0000527 participates in proliferation, invasion and migration of retinoblastoma cells via miR-646/BCL-2 axis

Molecular Biological Research on the Pathogenic Mechanism of Retinoblastoma

Retinoblastoma (RB) is the most common intraocular malignant tumor in children, primarily attributed to the bi-allelic loss of the RB1 gene in the developing retina. Despite significant progress in understanding the basic pathogenesis of RB, comprehensively unravelling the intricate network of genetics and epigenetics underlying RB tumorigenesis remains a major challenge. Conventional clinical treatment options are limited, and despite the continuous identification of genetic loci associated with cancer pathogenesis, the development of targeted therapies lags behind. This review focuses on the reported genomic and epigenomic alterations in retinoblastoma, summarizing potential therapeutic targets for RB and providing insights for research into targeted therapies.

Plasma Circular RNAs as Biomarkers for Breast Cancer

Breast cancer (BC) is currently the most common neoplasm, the second leading cause of cancer death in women worldwide, and is a major health problem. The discovery of new biomarkers is crucial to improve our knowledge of breast cancer and strengthen our clinical approaches to diagnosis, prognosis, and follow-up. In recent decades, there has been increasing interest in circulating RNA (circRNA) as modulators of gene expression involved in tumor development and progression. The study of circulating circRNAs (ccircRNAs) in plasma may provide new non-invasive diagnostic, prognostic, and predictive biomarkers for BC. This review describes the latest findings on BC-associated ccircRNAs in plasma and their clinical utility. Several ccircRNAs in plasma have shown great potential as BC biomarkers, especially from a diagnostic point of view. Mechanistically, most of the reported BC-associated ccircRNAs are involved in the regulation of cell survival, proliferation, and invasion, mainly via MAPK/AKT signaling pathways. However, the study of circRNAs is a relatively new area of research, and a larger number of studies will be crucial to confirm their potential as plasma biomarkers and to understand their involvement in BC.

Long non-coding RNA DSCAS regulates cisplatin sensitivity in lung squamous cell carcinoma by competitively binding to miR-646-3p

Background

Platinum-based chemotherapy is the main treatment for advanced lung squamous cell carcinoma (LUSC). Eventually, patients with LUSC develop resistance to cisplatin, which affects the prognosis. Hence, the researchers sought to find a lncRNA in LUSC that affects resistance to cisplatin.

Methods

The lncRNA microarray assay was used to screen the differential expression of lncRNA. qPCR was used to detect lncRNA DSCAS (DSCAS) expression in tissues and cell lines. Lentiviral transfection was used to regulate the expression of DSCAS. CCK-8, colony formation, wound healing, transwell, and flow cytometry assays were used to assess the biological behaviors and sensitivity to cisplatin of LUSC cell. RNA-RNA interaction was tested using the dual luciferase reporting assay, RNA-IP, and RNA-RNA pull-down assay. The downstream pathway of DSCAS was verified by qPCR and Western blotting assays.

Results

DSCAS was highly expressed in LUSC tissues and cells, and its expression levels were higher in cisplatin-insensitive tissues than in cisplatin-sensitive tissues. Elevation of DSCAS promoted cell proliferation, migration and invasion as well as increased cisplatin resistance of lung cancer cells, while demotion of DSCAS inhibited cell proliferation, migration and invasion as well as decreased the cisplatin resistance of lung cancer cells. DSCAS bound to miR-646-3p to regulate the expression of Bcl-2 and Survivin, which affected the cell apoptosis and sensitivity to cisplatin in LUSC cells.

Conclusions

DSCAS regulates biological behavior and cisplatin sensitivity in LUSC cells by competitively binding to miR-646-3p to mediate the expression of Survivin and Bcl-2, known as apoptosis-related proteins.

CREBZF mRNA nanoparticles suppress breast cancer progression through a positive feedback loop boosted by circPAPD4

BACKGROUND

Breast cancer (BC) negatively impacts the health of women worldwide. Circular RNAs (circRNAs) are a group of endogenous RNAs considered essential regulatory factor in BC tumorigenesis and progression. However, the underlying molecular mechanisms of circRNAs remain unclear.

METHODS

Expression levels of circPAPD4, miR-1269a, CREBZF, and ADAR1 in BC cell lines and tissues were measured using bioinformatics analysis, RT-qPCR, ISH, and IHC. Cell proliferation and apoptosis were measured using CCK8, EdU staining, flow cytometry, and TUNEL assays. Pearson correlation analysis, RNA pull-down, dual-luciferase reporter, and co-immunoprecipitation assays were used to explore the correlation among circPAPD4, miR-1269a, CREBZF, STAT3, and ADAR1. Effects of circPAPD4 overexpression on tumor progression were investigated using in vivo assays. Moreover, CREBZF mRNA delivered by polymeric nanoparticles (CREBZF-mRNA-NPs) was used to examine application value of our findings.

RESULTS

CircPAPD4 expression was low in BC tissues and cells. Functionally, circPAPD4 inhibited proliferation and promoted apoptosis in vitro and in vivo. Mechanistically, circPAPD4 biogenesis was regulated by ADAR1. And circPAPD4 promoted CREBZF expression by competitively binding to miR-1269a. More importantly, CREBZF promoted circPAPD4 expression by suppressing STAT3 dimerization and ADAR1 expression, revealing a novel positive feedback loop that curbed BC progression. Systematic delivery of CREBZF-mRNA-NPs effectively induced CREBZF expression and activated the positive feedback loop of circPAPD4/miR-1269a/CREBZF/STAT3/ADAR1, which might suppress BC progression in vitro and in vivo.

CONCLUSION

Our findings firstly illustrated that circPAPD4/miR-1269a/CREBZF/STAT3/ADAR1 positive feedback loop mediated BC progression, and delivering CREBZF mRNA nanoparticles suppressed BC progression in vitro and in vivo, which might provide novel insights into therapeutic strategies for breast cancer.

The functional role of circular RNAs in the pathogenesis of retinoblastoma: a new potential biomarker and therapeutic target?

Retinoblastoma (RB) is a common cancer in infants and children. It is a curable disease; however, a delayed diagnosis or treatment makes the treatment difficult. Genetic mutations have a central role in the pathogenesis of RB. Genetic materials such as RNAs (coding and non-coding RNAs) are also involved in the progression of the tumor. Circular RNA (circRNA) is the most recently identified RNA and is involved in regulating gene expression mainly through "microRNA sponges". The dysregulation of circRNAs has been observed in several diseases and tumors. Also, various studies have shown that circRNAs expression is changed in RB tissues. Due to their role in the pathogenesis of the disease, circRNAs might be helpful as a diagnostic or prognostic biomarker in patients with RB. In addition, circRNAs could be a suitable therapeutic target to treat RB in a targeted therapy approach.

Circular RNA in Retina: A Potential Biomarker and Therapeutic Target

Circular RNA (circRNA) is a newly discovered noncoding RNA, which forms a closed ring with more than 200 bases in length. CircRNA is formed by back splicing of precursor RNA, and its expression abundance in body fluid is up to 10 times that of homologous linear transcripts. Recently, novel activities for circRNA in various diseases have emerged, ranging from cancer therapy and neurodegenerative diseases. Here, we reviewed the literature on the biogenesis of circRNA and its relationship with retinal diseases in recent years. We first described the mechanism, existing form and main function of circRNA. Next, we also pinpoint that circRNA has great value in the diagnosis and treatment of retinal diseases represented by retinoblastoma, retinal degeneration, and diabetic retinopathy. By this review, we hope to explore more possibilities of circRNA in clinical diagnosis and treatment.

An Update on Circular RNA in Pediatric Cancers

Circular RNAs (circRNAs) are a class of single-stranded closed noncoding RNA molecules which are formed as a result of reverse splicing of mRNAs. Despite their relative abundance, only recently there appeared an increased interest in the understanding of their regulatory importance. Among their most relevant characteristics are high stability, abundance and evolutionary conservation among species. CircRNAs are implicated in several cellular functions, ranging from miRNA and protein sponges to transcriptional modulation and splicing. Additionally, circRNAs' aberrant expression in pathological conditions is bringing to light their possible use as diagnostic and prognostic biomarkers. Their use as indicator molecules of pathological changes is also supported by their peculiar covalent closed cyclic structure which bestows resistance to RNases. Their regulatory role in cancer pathogenesis and metastasis is supported by studies involving human tumors that have investigated different expression profiles of these molecules. As endogenous competitive RNA, circRNAs can regulate tumor proliferation and invasion and they arouse great consideration as potential therapeutic biomarkers and targets for cancer. In this review, we describe the most recent findings on circRNAs in the most common pediatric solid cancers (such as brain tumors, neuroblastomas, and sarcomas) and in more rare ones (such as Wilms tumors, hepatoblastomas, and retinoblastomas).

Role of non-coding RNAs and exosomal non-coding RNAs in retinoblastoma progression

Retinoblastoma (RB) is a rare aggressive intraocular malignancy of childhood that has the potential to affect vision, and can even be fatal in some children. While the tumor can be controlled efficiently at early stages, metastatic tumors lead to high mortality. Non-coding RNAs (ncRNAs) are implicated in a number of physiological cellular process, including differentiation, proliferation, migration, and invasion, The deregulation of ncRNAs is correlated with several diseases, particularly cancer. ncRNAs are categorized into two main groups based on their length, i.e. short and long ncRNAs. Moreover, ncRNA deregulation has been demonstrated to play a role in the pathogenesis and development of RB. Several ncRNAs, such as miR-491-3p, miR-613,and SUSD2 have been found to act as tumor suppressor genes in RB, but other ncRNAs, such as circ-E2F3, NEAT1, and TUG1 act as tumor promoter genes. Understanding the regulatory mechanisms of ncRNAs can provide new opportunities for RB therapy. In the present review, we discuss the functional roles of the most important ncRNAs in RB, their interaction with the genes responsible for RB initiation and progression, and possible future clinical applications as diagnostic and prognostic tools or as therapeutic targets.

Role of circular RNAs in retinoblastoma

Retinoblastoma (RB), the most common malignant retinal tumor among children under 3 years old, is lethal if left untreated. Early diagnosis, together with timely and effective treatment, is important to improve retinoblastoma-related outcomes. Circular RNAs (circRNAs), a new class of non-coding RNAs with the capacity to regulate cellular activities, have great potential in retinoblastoma diagnosis and treatment. Recent studies have identified circular RNAs that regulate multiple cellular processes involved in retinoblastoma, including cell viability, proliferation, apoptosis, autophagy, migration, and invasion. Six circular RNAs (circ-FAM158A, circ-DHDDS, circ-E2F3, circ-TRHDE, circ-E2F5, and circ-RNF20) promote disease progression and metastasis in retinoblastoma and function as oncogenic factors. Other circular RNAs, such as circ-TET1, circ-SHPRH, circ-MKLN1, and circ-CUL2, play tumor suppressive roles in retinoblastoma. At present, the studies on the regulatory mechanism of circular RNAs in retinoblastoma are not very clear. The purpose of this review is to summarize recent studies on the functional roles and molecular mechanisms of circular RNAs in retinoblastoma and highlight novel strategies for retinoblastoma diagnosis, prognosis, and treatment.

Circ_0000527 regulates proliferation, migration, and invasion of colorectal cancer SW620 cells by targeting miR-1253

BACKGROUND

The expression of circular RNAs (circRNAs) may be up-regulated/down-regulated in colorectal cancer, and they act as sponge molecules of microRNAs (miRNAs), negatively regulate the expression of miRNAs, and participate in the occurrence and development of colorectal cancer. It is known that circ_0000527 is highly expressed in tumor tissues such as osteosarcoma, and circ_0000527 has a complementary sequence with miR-1253, which is down-regulated in colorectal cancer tissues and cells. However, it is unknown whether circ_0000527 can regulate the expression of miR-1253 and thus affect the biological behavior of colorectal cancer cells.

AIM

To investigate the effect of circ_0000527 targeting miR-1253 on the proliferation, migration, and invasion of colorectal cancer SW620 cells.

METHODS

Tumor and tumor-adjacent tissue samples were collected from 41 colorectal cancer patients treated at our hospital from March 2020 to August 2020, and the expression of circ_0000527 and miR-1253 was detected by qRT-PCR. Human colorectal cancer SW620 cells were divided into si-NC group, si-circ_0000527 group, miR-NC group, miR-1253 group, si-circ_0000527 + anti-miR-NC group, and si-circ_0000527 + anti-miR-1253 group. CCK-8 assay, plate clone formation assay, scratch assay, and Transwell assay were used to detect cell proliferation, clone formation, migration, and invasion, respectively. Dual luciferase reporter assay was used to detect the targeting relationship between circ_0000527 and miR-1253.

RESULTS

In colorectal cancer tissues, the expression of circ_0000527 was increased (P < 0.05), and the expression of miR-1253 was decreased (P < 0.05). After transfection of SW620 cells with si-circ_0000527 or miR-1253 mimic, cell viability and wound healing rate were decreased (P < 0.05), and the number of cell clones and invasive cells was decreased (P < 0.05). Circ_0000527 could target and bind miR-1253. Co-transfection of si-circ_0000527 and anti-miR-1253 could reverse the effect of si-circ_0000527 on the biological behavior of SW620 cells.

CONCLUSION

Interference with the expression of circ_0000527 attenuates the ability of colorectal cancer cells to proliferate, form closes, migrate, and invade by up-regulating the expression of miR-1253.

CircRNA-Associated CeRNAs Regulatory Axes in Retinoblastoma: A Systematic Scoping Review

Retinoblastoma (RB) is one of the most common childhood cancers caused by RB gene mutations (tumor suppressor gene in various patients). A better understanding of molecular pathways and the development of new diagnostic approaches may lead to better treatment for RB patients. The number of studies on ceRNA axes is increasing, emphasizing the significance of these axes in RB. Circular RNAs (circRNAs) play a vital role in competing endogenous RNA (ceRNA) regulatory axes by sponging microRNAs and regulating gene expression. Because of the broadness of ceRNA interaction networks, they may assist in investigating treatment targets in RB. This study conducted a systematic scoping review to evaluate verified loops of ceRNA in RB, focusing on the ceRNA axis and its relationship to circRNAs. This scoping review was carried out using a six-step strategy and the Prisma guideline, and it involved systematically searching the publications of seven databases. Out of 363 records, sixteen articles were entirely consistent with the defined inclusion criteria and were summarized in the relevant table. The majority of the studies focused on the circRNAs circ_0000527, circ_0000034, and circTET1, with approximately two-fifths of the studies focusing on a single circRNA. Understanding the many features of this regulatory structure may help elucidate RB’s unknown causative factors and provide novel molecular potential therapeutic targets and medical fields.

Circ_0075804 regulates the expression of LASP1 by Targeting miR-1287-5p and thus affects the biological process of retinoblastoma

BACKGROUND

Increasing evidence reveals that circular RNA (circRNA) dysregulation is involved in retinoblastoma (RB) pathogenesis. To further realize the development of RB, we investigated the role and regulatory mechanism of circ_0075804 in RB.

METHODS

Real-time quantitative PCR (RT-qPCR) and western blot were employed for expression analysis. CCK-8 assay, EdU assay, colony formation assay, flow cytometry assay and transwell assay were performed to monitor cell phenotypes. Xenograft models were established to monitor the role of circ_0075804 on tumor growth. Tumor growth was assessed by the expression of Ki67, N-cadherin, MMP2 and MMP9 via IHC assay. The predicted binding sites between miR-1287-5p and circ_0075804 or LIM and SH3 protein 1 (LASP1) were validated by dual-luciferase reporter assay.

RESULTS

Upregulation of circ_0075804 and LASP1, and downregulation of miR-1287-5p were shown in RB tissues and cells. Circ_0075804 knockdown repressed RB cell growth, invasion and survival, and hindered tumor development in vivo. MiR-1287-5p was targeted by circ_0075804, and its repression largely reversed the functional effects of circ_0075804 knockdown. LASP1 was a functional target of miR-1287-5p. The inhibition of miR-1287-5p upregulation on RB cell proliferation, survival and invasion was reversed by LASP1 overexpression. Moreover, circ_0075804 knockdown weakened LASP1 expression via increasing miR-1287-5p.

CONCLUSION

Circ_0075804 promotes LASP1 expression by targeting miR-1287-5p, thus acting as a contributor to RB carcinogenesis.Highlights:Circ_0075804 is overexpressed in RB.Circ_0075804 knockdown inhibits RB cell malignant phenotypes and tumor growth in vivo.Circ_0075804 regulates RB cell behaviors by targeting miR-1287-5p.MiR-1287-5p affects RB cell behaviors by binding to LASP1.Circ_0075804 regulates LASP1 expression via targeting miR-1287-5p.

CircCUL2 suppresses retinoblastoma cells by regulating miR-214-5p/E2F2 Axis

The aim of this study was to investigate the effect of circCUL2 on the proliferation, invasion and migration of retinoblastoma cells by regulating the miR-214-5p/E2F2 axis. qRT-PCR and western blot were performed to detect the expressions of circCUL2, miR-214-5p and E2F2 in tumor tissues and adjacent normal tissues from retinoblastoma patients, and in normal human retinal epithelial cells ARPE-19 and human retinoblastoma cells Y79 and SO-Rb50. qRT-PCR and western blot were performed for the detection of RNA levels of circCUL2 and miR-214-5p and the mRNA and protein levels of E2F2, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay for cell proliferation ability, Transwell assay for cell invasion ability, and scratch assay for cell migration ability. Luciferase dual reporter assay was used to detect the targeting relationship between circCUL2 and miR-214-5p, and between miR-214-5p and E2F2. CircCUL2 and E2F2 were lowly expressed, while miR-214-5p was highly expressed in retinoblastoma tumor tissues and cells. Transfection with pcDNA3.1-CUL2 or miR-214-5p inhibitor inhibited the proliferation, invasion and migration of Y79 and SO-Rb50 cells compared with the negative control; while transfection with sh-CUL2 or miR-214-5p mimics promoted the proliferation, invasion and migration of Y79 and SO-Rb50 cells. CircCUL2 negatively regulated miR-214-5p, while miR-214-5p negatively regulated E2F2. Overexpression of miR-214-5p or silencing of E2F2 in SO-Rb50 cells partially reversed the inhibitory effect of circCUL2 on the proliferation, invasion and migration of retinoblastoma cells. CircCUL2 inhibited the proliferation, invasion and migration of retinoblastoma cells by regulating the miR-214-5p/E2F2 axis.

Circ_0000527 Drives Retinoblastoma Progression by Regulating miR-1236-3p/SMAD2 Pathway

PURPOSE

Circular RNAs (circRNAs) play essential roles in the progression of human tumors, including retinoblastoma (RB). In this study, we aimed to explore the functions and potential mechanisms of circ_0000527 in RB.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR), Western blot assay and immunohistochemistry (IHC) assay were conducted to determine the levels of circ_0000527, microRNA-1236-3p (miR-1236-3p) and SMAD family member 2 (SMAD2). RNase R assay and actinomycin D assay were conducted to analyze the characteristic of circ_0000527. Cell Counting Kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, and colony formation assay were performed for cell proliferation ability. Wound healing assay and transwell assay were applied to assess cell migration and invasion. Tube formation assay was utilized for angiogenesis ability. Flow cytometry analysis was adopted to analyze cell apoptosis. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to analyze the relationships among circ_0000527, miR-1236-3p, and SMAD2. Murine xenograft model assay was conducted for the role of circ_0000527 in vivo.

RESULTS

Circ_0000527 was overexpressed in RB patients and related to advanced TNM stages, optic nerve invasion and choroidal invasion. Circ_0000527 knockdown suppressed cell proliferation, migration, invasion and angiogenesis and promoted apoptosis in RB cells in vitro. Circ_0000527 sponged miR-1236-3p, which directly targeted SMAD2. MiR-1236-3p level was decreased in RB tissues and cells. MiR-1236-3p inhibition reversed circ_0000527 knockdown-mediated effects on RB cell malignant behaviors. Moreover, miR-1236-3p overexpression suppressed RB cell progression, with SMAD2 elevation abrogated the effect. Additionally, circ_0000527 knockdown restrained tumor formation in vivo.

CONCLUSIONS

Circ_0000527/miR-1236-3p/SMAD2 axis played a positive role in the progression of RB.

Hsa_circ_0000527 Downregulation Suppresses the Development of Retinoblastoma by Modulating the miR-27a-3p/HDAC9 Pathway

BACKGROUND

Accumulating evidence indicates that the progression of retinoblastoma (RB) may involve circRNA dysfunction. We aimed to disclose the role of hsa_circ_0000527 and its potential functional mechanism in RB.

METHODS

The expression of hsa_circ_0000527, miR-27a-3p and histone deacetylase 9 (HDAC9) mRNA was monitored using quantitative real-time polymerase chain reaction (qPCR). Functional assays, including cell proliferation and apoptosis, were investigated using cell counting kit-8 (CCK-8) assay, colony formation assay and flow cytometry assay. The expression of apoptosis-associated proteins and HDAC9 protein was detected by western blot. The targeting relationship between miR-27a-3p and hsa_circ_0000527 or HDAC9 was verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Besides, Xenograft models were constructed to confirm the effect of hsa_circ_0000527 in vivo.

RESULTS

Hsa_circ_0000527 and HDAC9 were upregulated, while miR-27a-3p was downregulated in RB tissues and cells. Hsa_circ_0000527 downregulation repressed RB cell proliferation and induced RB cell apoptosis. MiR-27a-3p was a target of hsa_circ_0000527, and hsa_circ_0000527 suppressed the expression of miR-27a-3p. MiR-27a-3p inhibition reversed the role of hsa_circ_0000527 downregulation. In addition, HDAC9 was a target of miR-27a-3p, and hsa_circ_0000527 indirectly regulated HDAC9 expression by targeting miR-27a-3p. MiR-27a-3p restoration inhibited RB cell proliferation and promoted apoptosis, which was reversed by HDAC9 overexpression. Hsa_circ_0000527 downregulation could inactivate the PI3K/AKT pathway. Moreover, hsa_circ_0000527 downregulation blocked tumor growth rate in vivo.

CONCLUSION

hsa_circ_0000527 downregulation blocked the progression of RB by regulating the miR-27a-3p/HDAC9 pathway, which might be associated with the inactivation of the PI3K/AKT pathway.

Circular RNA circ-FAM158A promotes retinoblastoma progression by regulating miR-138-5p/SLC7A5 axis

BACKGROUND

Mounting evidence has shown that circular RNAs (circRNAs) have vital roles in human cancers, including retinoblastoma (RB). The purpose of this study was to investigate the exact roles and underlying mechanism of circRNA ER membrane protein complex subunit 9 (circ-FAM158A) in RB.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was carried out to determine the expression levels of circ-FAM158A, miR-138-5p and solute carrier family 7 member 5 (SLC7A5). Cell proliferation was evaluated by Cell counting Kit-8 (CCK-8) assay and colony formation assay. Flow cytometry analysis was applied to determine cell cycle distribution and apoptosis rate. Transwell assay was conducted to assess cell migration and invasion. The interaction between miR-138-5p and circ-FAM158A or SLC7A5 was predicted by starBase v2.0 and confirmed by dual-luciferase reporter assay. Western blot assay was performed to examine the protein expression of SLC7A5. The mice xenograft model was established, immunohistochemistry (IHC) and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) assays were conducted to confirm the role of circ-FAM158A in vivo.

RESULTS

Circ-FAM158A and SLC7A5 were overexpressed and miR-138-5p was downregulated in RB tissues and cells. Circ-FAM158A knockdown inhibited RB cell proliferation, metastasis, and promoted apoptosis in vitro and in vivo. MiR-138-5p was a direct target of circ-FAM158A, and miR-138-5p inhibition reversed the inhibitory effect of circ-FAM158A silence on the progression of RB cells. Additionally, SLC7A5 was identified as a target of miR-138-5p, and SLC7A5 overexpression abated the anti-tumor roles of miR-138-5p in RB cells. Besides, circ-FAM158A positively regulated SLC7A5 expression by sponging miR-138-5p.

CONCLUSION

Circ-FAM158A knockdown inhibited the progression of RB by regulating miR-138-5p/SLC7A5 axis, which provided new insights into the pathogenesis of RB.

CircTET1 Inhibits Retinoblastoma Progression via Targeting miR-492 and miR-494-3p through Wnt/β-catenin Signaling Pathway

Purpose: Retinoblastoma (RB) is a frequent intraocular malignancy in children. Circular RNA (circRNA) plays an essential role in regulating the occurrence and development of tumors. This study aimed at investigating the function and molecular basis of hsa_circ_0093996 (circTET1) in RB.Methods: The expression of circTET1, miR-492 and miR-494-3p was examined using quantitative real-time polymerase chain reaction. Cell proliferation, cycle arrest, apoptosis, migration and invasion of RB cells were detected using Cell Counting Kit-8 (CCK-8), colony formation assay, flow cytometry, scratch assay and transwell analysis, respectively. The levels of matrix metalloproteinase (MMP) 2, MMP9 and Wnt/β-catenin pathway-related proteins were measured via western blot assay. The association between circTET1 and miR-492/miR-494-3p was validated via dual-luciferase reporter assay and RNA pull-down assay. Xenograft assay was employed to analyze tumor growth in vivo.Results: CircTET1 level was reduced, while miR-492 and miR-494-3p levels were increased in RB tissues and cells. Overexpression of circTET1 inhibited proliferation, migration and invasion, and promoted apoptosis and cell cycle arrest in Y79 and WERI-Rb1 cells. Moreover, circTET1 impeded RB cell progression by sponging miR-492/miR-494-3p. Also, up-regulation of circTET1 restrained Wnt/β-catenin pathway via regulating miR-492 and miR-494-3p. Furthermore, circTET1 suppressed tumor growth in xenograft models.Conclusion: CircTET1 inhibited RB progression by sponging miR-492/miR-494-3p and inactivating the Wnt/β-catenin pathway, which provided new insights for RB treatment.

Circ-E2F3 acts as a ceRNA for miR-204-5p to promote proliferation, metastasis and apoptosis inhibition in retinoblastoma by regulating ROCK1 expression

BACKGROUND

Circular RNA (circRNA) plays an important role in the malignant progression of many tumors, including retinoblastoma (RB). However, the role and regulatory mechanism of circ-E2F3 in RB have not been fully elucidated.

METHODS

Quantitative real-time PCR was used to measure circ-E2F3, miR-204-5p and Rho-associated protein kinase 1 (ROCK1) expression. Cell proliferation, apoptosis and metastasis were monitored by MTT, colony formation, flow cytometry, transwell and wound healing assays. Dual-luciferase reporter assay was employed to verify the relationship between miR-204-5p and circ-E2F3 or ROCK1. ROCK1 protein expression was detected by western blot assay. Mice xenograft models were built to assess the role of circ-E2F3 on RB tumor growth.

RESULTS

Circ-E2F3 was upregulated in RB tissues and cells. Silencing of circ-E2F3 inhibited the proliferation, migration, invasion, and induced the apoptosis of RB cells in vitro, as well as reduced RB tumor growth in vivo. MiR-204-5p could be sponged by circ-E2F3, and its inhibitor reversed the suppressive effect of circ-E2F3 silencing on RB progression. In addition, ROCK1 was confirmed to interact with miR-204-5p. MiR-204-5p regulated RB progression by targeting ROCK1. Also, circ-E2F3 positively regulated ROCK1 expression by sponging miR-204-5p.

CONCLUSION

Circ-E2F3 functioned as a tumor promoter in RB through the miR-204-5p/ROCK1 axis.

Hsa_circ_0099198 facilitates the progression of retinoblastoma by regulating miR-1287/LRP6 axis

Retinoblastoma (RB) is an intraocular malignancy that occurs in children. Circular RNAs (circRNAs) have been confirmed to play an essential role in tumorigenesis and development. This study aimed to ascertain the role and potential mechanism of hsa_circ_0099198 in RB. The levels of circ_0099198, microRNA-1287 (miR-1287) and low-density lipoprotein receptor-related protein 6 (LRP6) were determined by real-time quantitative polymerase chain reaction and Western blot. Cell proliferation was assessed by colony formation assay. Cell cycle arrest and apoptosis were evaluated by flow cytometry. Cell migration and invasion were tested using transwell assay. The activity of caspase-3/caspase-9 was examined with commercial kits. The interaction among circ_0099198, miR-1287 and LRP6 were verified by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay or RNA pull-down assay. Xenograft experiment was used to assess tumor growth in vivo. circ_0099198 and LRP6 levels were increased, while miR-1287 level was reduced in RB cells. circ_0099198 silencing suppressed proliferation and metastasis and expedited cell cycle arrest and apoptosis in Y79 and So-RB50 cells. In addition, depletion of circ_0099198 inhibited RB cell progression via regulating miR-1287/LRP6 axis. Moreover, knockdown of circ_0099198 blocked the growth of xenograft tumors. circ_0099198 contributed to RB progression by sponging miR-1287 and up-regulating LRP6, which provided novel biomarkers for RB therapy.

Circ_0000527 Promotes Retinoblastoma Progression through Modulating miR-98-5p/XIAP Pathway

Purpose: Retinoblastoma (RB) is an intraocular malignancy that often occurs in childhood. Circular RNAs (circRNAs) play crucial roles in regulating the malignant phenotypes of various tumors. This study aimed to explore the role and potential mechanism of circ_0000527 in RB.Methods: The levels of circ_0000527, microRNA-98-5p (miR-98-5p) and X-linked inhibitor of apoptosis (XIAP) were determined by qRT-PCR or western blot. Cell proliferation was detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and colony formation assays. Cell apoptosis, migration and invasion were evaluated by flow cytometry, transwell and scratch assays. Xenograft assay was conducted to analyze tumor growth in vivo. The binding relationship between miR-98-5p and circ_0000527 or XIAP was verified by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays.Results: Circ_0000527 and XIAP levels were increased, while miR-98-5p level was reduced in RB tissues and cells. Silencing of circ_0000527 suppressed the proliferation, migration and invasion of RB cells and promoted apoptosis. In addition, knockdown of circ_0000527 inhibited tumor growth in xenograft mice. Besides, circ_0000527 sponged miR-98-5p to regulate RB cell progression, and miR-98-5p targeted XIAP to mediate RB cell development. Moreover, circ_0000527 modulated XIAP expression via sequestering miR-98-5p.Conclusion: Circ_0000527 facilitated RB progression via regulating miR-98-5p/XIAP axis, which provided a promising therapeutic target for RB.

Circ_0000527 promotes osteosarcoma cell progression through modulating miR-646/ARL2 axis

Accumulating evidence shows that circRNAs play critical roles in the development of human tumors. We observed that circ_0000527 was overexpressed in osteosarcoma cells (SAOS-2, HOS, MG-63 and U2OS) compared in hFOB1.19 cells. We demonstrated that the circ_0000527 level was higher in osteosarcoma specimens than in non-tumor specimens. The ectopic expression of circ_0000527 was shown to induce cell growth, cell cycle progression and the secretion of inflammatory mediators, including IL-1β, IL-6, IL-8 and TNF-α. We demonstrated that circ_0000527 sponges miR-646 in osteosarcoma cells and that ARL2 is a target gene of miR-646. MiR-646 expression was decreased and ARL2 was overexpressed in osteosarcoma cells (SAOS-2, HOS, MG-63 and U2OS) compared to hFOB1.19 cells. Overexpression of circ_0000527 was demonstrated to induce ARL2 expression in MG-63 cells. We showed that miR-646 was downregulated in osteosarcoma specimens compared to that of non-tumor specimens and that the level of circ_0000527 was negatively correlated with miR-646 expression in osteosarcoma specimens. The elevated expression of circ_0000527 was shown to promote cell growth and cell cycle progression by modulating miR-646 expression. The ectopic expression of circ_0000527 was shown to promote cell growth, cell cycle progression and the secretion of inflammatory mediators by modulating ARL2. The present study suggested that the circ_0000527/miR-646/ARL2 axis may be a potential treatment target for osteosarcoma.

Circ_0119872 promotes uveal melanoma development by regulating the miR-622/G3BP1 axis and downstream signalling pathways

Background

The abnormal expression of circular RNAs (circRNAs) in uveal melanoma (UM) has been revealed, but the specific underlying molecular mechanism of their association with UM development has not been fully explored.

Methods

The levels of circ_0119872, G3BP1 and miR-622 in UM cell lines and tissues were determined by quantitative real-time PCR (qRT-PCR) and western blotting assays. In vitro and in vivo assays were performed to investigate the function of circ_0119872 in the tumorigenesis of UM cells. The relationships among circ_0119872, miR-622 and G3BP1 were predicted using bioinformatic tools and verified by RNA-FISH, RNA pull-down and dual-luciferase reporter assays. The effects of circ_0119872 on Wnt/β-catenin and mTOR signalling pathways were determined by gene set enrichment analysis (GSEA) and western blotting.

Results

We found that circ_0119872 is upregulated in UM cell lines and tissues. Moreover, overexpression of circ_0119872 promotes the malignancy of UM cells, while silencing of circ_0119872 inhibits it. In addition, circ_0119872 can directly interact with miR-622 as a miRNA sponge that regulates the expression of the miR-622 target gene G3BP1 as well as downstream Wnt/β-catenin and mTOR signalling pathways.

Conclusions

Circ_0119872 may act as an oncogene in UM through a novel circ_0119872/miR-622/G3BP1 axis, activating the Wnt/β-catenin and mTOR signalling pathways, which in turn may provide potential biomarkers and therapeutic targets for the management of UM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01833-w.

Circular RNAs in childhood-related diseases and cancers: A review

Research into the diagnosis, treatment and prevention of childhood-related diseases is the key to reducing their morbidity and mortality. Circular RNAs (circRNAs) play critical roles, both in physiology and pathology, and there is ample evidence to show that they play varying roles in tissue development and gene regulation. Studies on circRNAs in different childhood-related diseases have confirmed their great potential for disease prevention and treatment. These breakthroughs highlight the pathological role of circRNAs in cancers, as well as cardiovascular and hereditary childhood illnesses. In this review, we summarize the role of circRNAs in childhood-related diseases and cancer, and provide an update of the possible diagnostic and therapeutic application of circRNAs.

Circular RNA hsa_circ_0000034 promotes the progression of retinoblastoma via sponging microRNA-361-3p

Retinoblastoma is the commonest eye cancer occurring in the pediatric population. Circular RNAs (circRNAs) are essential regulators of tumorigenesis and development. The current experiment delves into the function and molecular basis of hsa_circ_0000034 in retinoblastoma progression. In the study, these series of experiments noted an upregulation of hsa_circ_0000034 in retinoblastoma cell lines and tissues. Retinoblastoma patients with raised hsa_circ_0000034 expressions were more likely to possess a more progressive International Integrated Reporting Council (IIRC) stage and optic nerve invasion. hsa_circ_0000034 knockdown caused a marked suppression in the proliferation and invasion of retinoblastoma cells in vitro. Mechanistically, hsa_circ_0000034 appeared to serve as a competitive endogenous RNA (ceRNA) in retinoblastoma through miR-361-3p sponging. In conclusion, our data proved that hsa_circ_0000034 promoted the oncogenicity of retinoblastoma via regulation of miR-361-3p expression, a finding that may contribute toward retinoblastoma therapeutics.

Circular RNA circ_HN1 facilitates gastric cancer progression through modulation of the miR-302b-3p/ROCK2 axis

Gastric cancer (GC) is a malignant tumor with high morbidity and mortality in the world. Circular RNA hsa_circHN1_005 (circ_HN1), also termed as hsa_circ_0045602, is reported as an oncogene in GC. However, the molecular mechanism of circ_HN1 in GC development has not been fully explored. Here, we surveyed the regulatory mechanism of circ_HN1 in GC progression. The levels of circ_HN1, miR-302b-3p, and rho-associated coiled-coil containing protein kinase 2 (ROCK2) mRNA were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation, apoptosis, colony formation, cell cycle progresion, migration, and invasion were determined by using cell counting, flow cytometry, colony formation, or transwell assays. Protein levels were detected with Western blotting. The relationship between circ_HN1 or ROCK2 and miR-302b-3p was verified via dual luciferase reporter or RNA immunoprecipitation (RIP) assays. The role of circ_HN1 in vivo was confirmed by xenograft assay. We observed that circ_HN1 and ROCK2 were upregulated while miR-302b-3p was downregulated in GC tissues and cells. Circ_HN1 silencing slowed tumor growth in vivo and impeded cell proliferation migration, invasion, and facilitated cell apoptosis in GC cells in vitro. Circ_HN1 sponged miR-302b-3p to regulate ROCK2 expression. MiR-302b-3p inhibitor reversed circ_HN1 silencing-mediated influence on the malignant behaviors of GC cells. Furthermore, ROCK2 overexpression restored miR-302b-3p mimic-mediated impacts on cell malignant behaviors in GC cells. In conclusion, circ_HN1 exerted an oncogenic role in GC through upregulating ROCK2 via sponging miR-302b-3p, offering evidence that circ_HN1 is a potential target for GC therapy.