Circ_0084927 Facilitates Cervical Cancer Development via Sponging miR-142-3p and Upregulating ARL2

Circular RNAs in Cell Cycle Regulation of Cancers

Cancer has been one of the most problematic health issues globally. Typically, all cancers share a common characteristic or cancer hallmark, such as sustaining cell proliferation, evading growth suppressors, and enabling replicative immortality. Indeed, cell cycle regulation in cancer is often found to be dysregulated, leading to an increase in aggressiveness. These dysregulations are partly due to the aberrant cellular signaling pathway. In recent years, circular RNAs (circRNAs) have been widely studied and classified as one of the regulators in various cancers. Numerous studies have reported that circRNAs antagonize or promote cancer progression through the modulation of cell cycle regulators or their associated signaling pathways, directly or indirectly. Mostly, circRNAs are known to act as microRNA (miRNA) sponges. However, they also hold additional mechanisms for regulating cellular activity, including protein binding, RNA-binding protein (RBP) recruitment, and protein translation. This review will discuss the current knowledge of how circRNAs regulate cell cycle-related proteins through the abovementioned mechanisms in different cancers.

Circ_0051428 targeting miR-885-3p/MMP2 axis enhances the malignancy of cervical cancer

Circular RNAs (circRNAs) are key regulators of cervical cancer (CC) progression. This study aimed to elucidate the role and mechanism of circ_0051428, a novel circRNA, in CC tumorigenesis. Quantitative real-time polymerase chain reaction and western blotting analyses confirmed that circ_0051428 and matrix metalloprotein-2 (MMP2) were overexpressed in CC, whereas the microRNA miR-885-3p was poorly expressed. After performing a series of in vitro and in vivo experiments, circ_0051428 knockdown was shown to repress CC cell invasion and proliferation in vitro, and hamper tumor formation in vivo. Dual-luciferase reporter and RNA-binding protein immunoprecipitation experiments verified that circ_0051428 interacts with miR-885-3p to regulate the target gene MMP2 of miR-885-3p in CC. In addition, miR-885-3p knockdown offset the anticancer effects of circ_0051428 or MMP2 knockdown on CC cell malignancy. Overall, this study revealed that circ_0051428 executes a tumor-promoting function in CC pathogenesis by modulating the miR-885-3p/MMP2 axis. Our findings provide a novel approach for CC treatment.

Hsa_circ_0017956 Acts as miR-758-3p Sponge to Facilitate the Progression of Non-small-Cell Lung Cancer by Regulating FOXP4 Expression

Accumulating studies have demonstrated the important role of circular RNAs (circRNAs) in the progression of different human tumors, including non-small-cell lung cancer (NSCLC). The purpose of this study was to deeply study the function and mechanism of circ_0017956 in NSCLC. Real-time quantitative polymerase chain reaction (RT-qPCR) was applied to detect the expression of circ_0017956, microRNA-758-3p (miR-758-3p), and Forkhead Box P4 (FOXP4). Western blot was performed to determine the protein levels. Cell proliferation was examined by cell counting kit-8 (CCK-8) assay and 5-ethynyl-2'-deoxyuridine (EdU) assay. Flow cytometry was used to evaluate the apoptosis of NSCLC cells. Transwell assay was applied to detect cell migratory and invasive capacities. The angiogenesis ability was evaluated by tube formation experiment. The target relationship between miR-758-3p and circ_0017956 or FOXP4 was confirmed by dual-luciferase reporter assay. Animal experiment was conducted to assess the effect of circ_0017956 in vivo. Circ_0017956 and FOXP4 were upregulated, while miR-758-3p was downregulated in NSCLC tissues and cells. Silencing of circ_0017956 significantly suppressed cell proliferation, migration, invasion, and angiogenesis, but promoted cell apoptosis in NSCLC cells. Mechanically, circ_0017956 functioned as a sponge for miR-758-3p and miR-758-3p could directly interact with FOXP4. Moreover, silencing of miR-758-3p or overexpression of FOXP4 could overturn the anticancer influence of circ_0017956 interference on NSCLC cells. Besides that, circ_0017956 knockdown hindered tumor growth in vivo. Altogether, circ_0017956 promoted the progression of NSCLC by regulating FOXP4 through sponging miR-758-3p.

The role and mechanism of circ-BNC2 on the malignant progression of oral squamous cell carcinoma

BACKGROUND

Circular RNAs (circRNAs) play a key part in the progression of oral squamous cell carcinoma (OSCC). However, the role of circ-BNC2 (circRNA ID hsa_circ_0086414) in OSCC progression is still unclear.

METHODS

Plasmid transfection was used to induce overexpression of circ-BNC2. RNA expression of circ-BNC2, microRNA-142-3p (miR-142-3p) and GNAS complex locus (GNAS) was detected by quantitative real-time polymerase chain reaction. Protein expression was assessed by western blot assay or immunohistochemistry assay. Cell proliferation was investigated by 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, colony formation assay and flow cytometry analysis. Cell migratory and invasive abilities and cell apoptosis were assessed by transwell assay and flow cytometry analysis, respectively. Oxidative stress was evaluated by superoxide dismutase activity detection assay, lipid peroxidation malondialdehyde assay and cellular reactive oxygen species assay. The binding relationship between miR-142-3p and circ-BNC2 or GNAS was proved by dual-luciferase reporter assay and RNA immunoprecipitation assay. The impacts of circ-BNC2 overexpression on tumor growth in vivo were unveiled by a xenograft mouse model assay.

RESULTS

Circ-BNC2 expression was downregulated in OSCC tissues and cells when compared with adjacent healthy tissues and normal human oral keratinocytes. Circ-BNC2 overexpression repressed the proliferation, migration and invasion of OSCC cells but induced cell apoptosis and oxidative stress. Additionally, circ-BNC2 overexpression inhibited tumor growth in vivo. Furthermore, circ-BNC2 bound to miR-142-3p, and miR-142-3p targeted GNAS. MiR-142-3p mimic attenuated circ-BNC2 overexpression-mediated effects on the proliferation, migration, invasion, apoptosis and oxidative stress of OSCC cells. The regulation of miR-142-3p in OSCC cell tumor properties involved GNAS. Further, circ-BNC2 introduction promoted GNAS expression by inhibiting miR-142-3p.

CONCLUSION

Circ-BNC2 suppressed OSCC malignant progression by upregulating GNAS expression in a miR-142-3p-dependent manner, which suggested that circ-BNC2 might be a novel target for OSCC therapy.

Long Non-Coding RNA ZSCAN16-AS1 Promotes the Malignant Progression of Melanoma Through Regulating the miR-503-5p/ARL2 Axis

Background

LncRNA zinc finger and SCAN domain containing 16 antisense RNA 1 (ZSCAN16-AS1), a newly identified lncRNA, has been proven to accelerate hepatocellular carcinoma progression. However, the function and molecular mechanism of ZSCAN16-AS1 in melanoma are still unknown.

Methods

The level of ZSCAN16-AS1 in melanoma tissues was detected and reported in The Cancer Genome Atlas (TCGA) and GEO#GSE15605. CCK-8, Transwell and flow cytometry assays were used to explore the role of ZSCAN16-AS1 in melanoma cells. Luciferase reporter assays and RNA pull-down assays were used to verify the molecular mechanism of ZSCAN16-AS1.

Results

Here, we found that ZSCAN16-AS1 expression was increased in melanoma. We confirmed that ZSCAN16-AS1 promotes the growth and metastasis of melanoma. ZSCAN16-AS1 exerts its pro-tumour role through sponging of miR-503-5p to liberate ADP-ribosylation factor-like protein 2 (ARL2) mRNA transcripts.

Conclusion

These results demonstrated the role and molecular mechanism of ZSCAN16-AS1 in the occurrence and development of melanoma. Therefore, ZSCAN16-AS1 may be used as a specific biomarker in the diagnosis and treatment of melanoma patients.

circRNA THBS1 silencing inhibits the malignant biological behavior of cervical cancer cells via the regulation of miR-543/HMGB2 axis

Circular RNA (circRNA) THBS1 has been shown to exist as an oncogene in non-small-cell lung cancer, but its role in cervical cancer is still unclear. Our experiment aimed to uncover the functions and specific mechanism of circRNA THBS1 in cervical cancer cells. Levels of circRNA THBS1 and miR-543 in cervical cancer tissues and cell lines were assessed by RT-qPCR. starBase and dual luciferase reporter gene assay were applied for investigating the correlation between miR-543 and circRNA THBS1/HMGB2. Cell proliferation and apoptosis were evaluated by MTT and flow cytometry, respectively. Furthermore, the levels of HMGB2, E-cadherin, and N-cadherin in HeLa cells were determined by RT-qPCR and western blot analysis. Our data revealed that circRNA THBS1 was significantly upregulated and miR-543 was low expressed in cervical cancer tissues and cell lines. circRNA THBS1 interacted with miR-543 and negatively regulated miR-543 expression in HeLa cells. Silencing of circRNA THBS1 remarkably suppressed HeLa cells' viability, accelerated cells' apoptosis, and inhibited the EMT of HeLa cells, while these changes were reversed by miR-543 inhibitor. Moreover, miR-543 affected HeLa cells by targeting HMGB2. In conclusion, circRNA THBS1 silencing inhibited the malignant biological behaviors of cervical cancer cells via the regulation of miR-543/HMGB2 axis.

Circular RNA circ_0000212 accelerates cervical cancer progression by acting as a miR-625-5p sponge to upregulate PTP4A1

Cervical cancer is one of the most common malignant tumors in women. Circular RNA (circRNA) has been shown to play a crucial role in cervical cancer. Here, the aim of this study was to explore the functions and a novel miRNA/mRNA network underlying circ_0000212 in cervical cancer regulation. The expression of circ_000212, miR-625-5p and Protein Tyrosine Phosphatase 4A1 (PTP4A1) mRNA was measured by quantitative real-time PCR (qRT-PCR). 5-ethynyl-2'-deoxyuridine assay was conducted to detect the proliferation of cervical cancer cells. Wound healing and transwell assays were employed to assess cell migration and invasion. The angiogenesis abilities of cervical cancer cells were evaluated by tube formation assay. Flow cytometry was performed for analyzing cell apoptosis. The expression of PTP4A1 protein and apoptosis-relative protein were detected via western blot. The dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were employed to clarify the interaction between circ_0000212 or PTP4A1 and miR-625-5p. The impact of circ_0000212 on cervical cancer growth in vivo was detected by xenograft assay. Circ_0000212 and PTP4A1 were highly expressed and miR-625-5p expression level was decreased in cervical cancer. Circ_0000212 silencing suppressed cervical cancer cell proliferation, migration, invasion and angiogenesis while promoting apoptosis. MiR-625-5p was targeted by circ_0000212, and miR-625-5p inhibition reversed the effects of circ_0000212 knockdown. MiR-625-5p directly targeted PTP4A1, and the inhibitory effect of miR-625-5p on the malignant progression of cervical cancer was reversed after PTP4A1 overexpression. In-vivo assays validated that circ_0000212 promoted cervical cancer tumor growth in vivo . circ_0000212 acted as an oncogene in cervical cancer progression, and knockdown of circ_0000212 repressed cervical cancer development by increasing miR-625-5p and decreasing PTP4A1.

Circ_0085616 contributes to the radio-resistance and progression of cervical cancer by targeting miR-541-3p/ARL2 signaling

BACKGROUND

Circular RNAs (circRNAs) play crucial regulatory roles in cancer progression and the development of radio-resistance. Here, we intended to explore the role of circ_0085616 in cervical cancer progression and its associated mechanism.

METHODS

Colony formation assay was employed to analyze the radio-resistance and proliferation of cervical cancer cells. Cell proliferation ability was also assessed by 5-ethynyl-2'-deoxyuridine (EdU) assay. Cell apoptosis was analyzed by flow cytometry. Tube formation assay was performed to analyze cell angiogenesis ability. Transwell assays were conducted to measure cell migration and invasion abilities. Dual-luciferase reporter assay was utilized to verify the target relationships. Xenograft mice model was used to analyze the role of circ_0085616 in tumor growth in vivo.

RESULTS

Circ_0085616 expression was elevated in cervical cancer tissues and cell lines. Circ_0085616 interference suppressed the radio-resistance, proliferation, tube formation, migration, and invasion and elevated the apoptosis rate of cervical cancer cells. Circ_0085616 acted as a sponge for microRNA-541-3p (miR-541-3p), and miR-541-3p was negatively regulated by circ_0085616 in cervical cancer cells. Circ_0085616 absence-induced changes in the behaviors of cervical cancer cells were largely overturned by anti-miR-541-3p. miR-541-3p negatively regulated ADP ribosylation factor like GTPase 2 (ARL2) expression by binding to its 3' untranslated region (3'UTR). miR-541-3p mimic-induced effects were largely reversed by pcDNA-ARL2 in cervical cancer cells. Circ_0085616 positively regulated ARL2 expression by sequestering miR-541-3p. Circ_0085616 absence significantly inhibited the tumor growth in vivo.

CONCLUSION

Circ_0085616 contributed to the radio-resistance and progression of cervical cancer partly through mediating the miR-541-3p/ARL2 axis.

Circ_0057558 accelerates the development of prostate cancer through miR-1238-3p/SEPT2 axis

BACKGROUND

Prostate cancer (PCa) is one of the most common malignant tumors in males with high morbidity and mortality. Existing studies have demonstrated that circ_0057558 may be a molecular marker affecting PCa. However, its detailed roles in PCa remain unclear.

METHODS

The levels of circ_0057558, miR-1238-3p and Septin 2 (SEPT2) were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Cell counting kit-8 (CCK-8) assay, colony formation assay, 5-Ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry assay, wound healing assay, transwell assay and tube formation assay were conducted for cell function identification. Xenograft tumor experiment was used to test the effect of circ_0057558 in vivo. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were conducted to determine the relationships between miR-1238-3p and circ_0057558 or SEPT2.

RESULTS

We identified that circ_0057558 level was elevated in PCa, and silencing circ_0057558 restrained PCa cell proliferation, survival, migration, invasion and angiogenesis. Circ_0057558 could sponge miR-1238-3p, and SEPT2 was the target of miR-1238-3p. Circ_0057558 promoted the expression of SEPT2 by negatively regulating miR-1238-3p, resulting in promotion of PCa progression. The effects of circ_0057558 knockdown in PCa development were overturned by the lack of miR-1238-3p. Also, overexpression of SEPT2 abolished the suppressive impacts of miR-1238-3p on PCa progression.

CONCLUSION

As a tumor promoter, circ_0057558 regulated the expression of miR-1238-3p and SEPT2 and facilitated PCa progression. These results indicated that circ_0057558 was a potential therapeutic marker of PCa.

The circCDK17/miR-122-5p/ASF1B axis regulates the progression of cervical cancer

BACKGROUND

Cervical cancer (CC) ranks fourth in terms of incidence and fourth in mortality overall in women worldwide. Circular RNAs (circRNAs) have been shown to be involved in the development of CC. However, the function of circRNA cyclin dependent kinase 17 (circCDK17, hsa_circ_0002762) in CC pathogenesis has not been studied.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of related genes. MTT, thymidine analog 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, transwell and wound-healing assays were designed to analyze cell proliferation, cell cycle progression, migration and invasion, respectively. Western blot was utilized to examine the protein levels of Cyclin D1, E-cadherin and Vimentin. The relationship between miR-122-5p and circCDK17 or ASF1B was verified by dual-luciferase reporter assay. The xenograft model was established to study the role of circCDK17 in vivo.

RESULTS

CircCDK17 and anti-silencing function 1B histone chaperone (ASF1B) were highly expressed in CC tissues and cells. Silencing circCDK17 reduced the proliferation, migration and invasion of CC cells. MiR-122-5p was a target of circCDK17. Silencing circCDK17 inhibited the malignant behaviors of CC cells by releasing miR-122-5p. Moreover, ASF1B was a target of miR-122-5p. Overexpression of ASF1B partially restored the inhibitory effects of circCDK17 silencing on cell proliferation, migration and invasion. Animal experiments confirmed the anti-tumor effect of circCDK17 knockdown in vivo.

CONCLUSION

Our study demonstrates that circCDK17 regulates the expression of ASF1B by miR-122-5p competition and thus promotes the development of CC, providing a novel targeted therapy for CC.

Circ_0006646 Accelerates the Growth and Metastasis of Cervical Cancer by Elevating RRM2 Through miR-758-3p

Cervical cancer (CC) is the fourth most common cancer in women, and circular RNAs (circRNAs) have been shown to regulate CC development. However, the role of circ_0006646 in CC progression is still unclear. The levels of circ_0006646, miR-758-3p, and ribonucleotide reductase regulatory subunit M2 (RRM2) were evaluated by quantitative real-time PCR. Cell proliferation was tested by cell counting kit 8 and 5-ethynyl-2'-deoxyuridine assays. Flow cytometry was used to test cell apoptosis. Migration and invasion were estimated by transwell assay. Western blot assay was performed to examine protein expression. Dual-luciferase reporter assay, RIP assay, and RNA pull down assay were used to analyze the connection between miR-758-3p and circ_0006646 or RRM2. Tumor growth was detected by in vivo experiments. Exosomes were isolated form CC patients and healthy controls. Circ_0006646 expression was elevated in CC cells, and its knockdown suppressed CC cell growth, migration, and invasion. MiR-758-3p was sponged by circ_0006646, and RRM2 was targeted by miR-758-3p. In addition, the effects of circ_0006646 depletion on CC cell progression were overturned by miR-758-3p inhibitor, and either RRM2 overexpression reversed those effects of miR-758-3p overexpression on CC cell progression. Circ_0006646 was highly expressed in the exosomes of CC patients. Circ_0006646 expedited CC cell growth and metastasis by regulating miR-758-3p/RRM2 axis, and exosomal circ_0006646 might be a potential diagnostic indicator of CC.

Circular RNAs as emerging players in cervical cancer tumorigenesis; A review to roles and biomarker potentials

Cervical cancer is the most lethal gynecological cancer among women worldwide. Most of the patients are diagnosed at the advanced stages due to late diagnosis and lack of accessible and valuable approaches for early detection of the disease. Circular RNAs (circRNAs) are a distinguishable class of non-coding RNAs with characteristic loop structures. Although their function has not been completely elucidated; however, recent evidence has suggested regulatory functions for circRNAs on gene expression controlling various biological functions like cell growth and apoptosis, development, embryogenesis, and pathogenesis of human diseases particularly cancers. Studies show the role of dysregulated circRNAs in biological processes including cell proliferation, migration, invasion, apoptosis, angiogenesis, and chemoresistance contributing to affect tumorigenesis in ovarian cancer cells, animal, and clinical studies. These effects can be defined as consistent with several tumorigenesis characteristics, which are defined as "hallmarks of cancer". Additionally, dysregulated circRNAs exhibit prognostic, and diagnostic potentials both in the prediction of prognosis in ovarian cancer patients, and also their discrimination from healthy individuals. Furthermore, targeting circRNAs has shown positive results in the suppression of malignant features of cancer cells, and also in overcoming chemoresistance. In this review, I have gathered the majority of studies evaluating the role of circRNAs in the development, and progression of cervical cancer, and also have discussed prognostic, diagnostic, and therapeutic potentials of circRNAs for clinical applications in cervical cancer patients.

Effect of circPUM1 on radioresistance of cervical cancer cells through targeting miR-144-3p

OBJECTIVE

To investigate the effect of circular RNA pumilio RNA binding family member (circPUM) 1 on radioresistance of cervical cancer cells and its mechanism.

METHODS

Cancer tissue and corresponding paricancerous tissue samples were collected from 47 patients with cervical cancer who underwent surgical treatment in the Second Affiliated Hospital of Zhengzhou University from August 2019 to February 2020. The expression levels of circPUM1 and miR-144-3p in cervical cancer tissues and paricancerous tissues were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The Pearson method was used to analyze the correlation between circPUM1 and miR-144-3p expression in cervical cancer tissues. circPUM1 lentiviral short hairpin RNA (sh-circPUM1) and its negative control (sh-NC), miR-144-3p oligonucleotide mimic (miR-144-3p mimic) and its negative control (miR-NC), sh-circPUM1 and miR-144-3p inhibitor (anti-miR), and sh-circPUM1 and anti-miR negative control (anti-miR-NC) were transfected into human cervical carcinoma SiHa cells, respectively, and the cells were irradiated with 0 and 4 Gy irradiation doses. Cell proliferation, colony formation, apoptosis, migration and invasion were detected by cell counting kit (CCK-8 method), plate colony formation assay, flow cytometry and Transwell assay, respectively. The protein expression of cleaved-caspase3 was detected by Western blotting. The targeting relationship between circPUM1 and miR-144-3p was analyzed with Starbase platform.

RESULTS

Compared with adjacent tissue, the expression of circPUM1 in cervical cancer tissue was significantly increased ( P<0.05), while the expression of miR-144-3p was decreased ( P<0.05). The circPUM1 was negatively correlated with miR-144-3p ( r=-0.9282, P<0.01). After transfection with sh-circPUM1 or miR-144-3p mimic, the inhibition rate of cell proliferation, the rate of apoptosis and the expression level of cleaved-caspase3 protein increased (all P<0.05), while the number of colonies formed, migrated and invaded cells decreased (all P<0.05). CircPUM1 could targeted to miR-144-3p. After co-transfection of sh-circPUM1 and anti-miR, the inhibition rate of cell proliferation, the rate of apoptosis and the expression level of cleaved-caspase3 protein significantly decreased (all P<0.05), while the number of colonies formed, migrated and invaded cells increased (all P<0.05).

CONCLUSION

Silencing circPUM1 may inhibit the proliferation, colony formation, migration, invasion and induce apoptosis of cervical cancer cells through targeting and regulating the expression of miR-144-3p.

CircZDBF2 up-regulates RNF145 by ceRNA model and recruits CEBPB to accelerate oral squamous cell carcinoma progression via NFκB signaling pathway

Background

Oral squamous cell carcinoma (OSCC), as one of the commonest malignancies showing poor prognosis, has been increasingly suggested to be modulated by circular RNAs (circRNAs). Through GEO (Gene Expression Omnibus) database, a circRNA derived from ZDBF2 (circZDBF2) was uncovered to be with high expression in OSCC tissues, while how it may function in OSCC remains unclear.

Methods

CircZDBF2 expression was firstly verified in OSCC cells via qRT-PCR. CCK-8, along with colony formation, wound healing, transwell and western blot assays was performed to assess the malignant cell behaviors in OSCC cells. Further, RNA pull down assay, RIP assay, as well as luciferase reporter assay was performed to testify the interaction between circZDBF2 and RNAs.

Results

CircZDBF2 expressed at a high level in OSCC cells and it accelerated OSCC cell proliferation, migration, invasion as well as EMT (epithelial-mesenchymal transition) process. Further, circZDBF2 sponged miR-362-5p and miR-500b-5p in OSCC cells to release their target ring finger protein 145 (RNF145). RNF145 expressed at a high level in OSCC cells and circZDBF2 facilitated RNF145 transcription by recruiting the transcription factor CCAAT enhancer binding protein beta (CEBPB). Moreover, RNF145 activated NFκB (nuclear factor kappa B) signaling pathway and regulated IL-8 (C-X-C motif chemokine ligand 8) transcription.

Conclusion

CircZDBF2 up-regulated RNF145 expression by sponging miR-362-5p and miR-500b-5p and recruiting CEBPB, thereby promoting OSCC progression via NFκB signaling pathway. The findings recommend circZDBF2 as a probable therapeutic target for OSCC.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03347-1.

CircFAM53B promotes the proliferation and metastasis of glioma through activating the c-MET/PI3K/AKT pathway via sponging miR-532-3p

Increasing evidence reveals that circular RNAs (circRNAs) regulate multiple biological functions in glioma. Previously, several reports have illustrated that circFAM53B contributes to cancer development. However, the functions and mechanisms of circFAM53B in glioma remain elusive. Here, we gauged the circFAM53B profile in glioma tissues and cell lines and conducted gain-of-function assays of circFAM53B to verify circFAM53B's influence on the proliferation and metastasis of glioma cells (including A172 and LN18). As a result, circFAM53B was up-regulated in glioma tissues (vs. the matched non-tumor tissues). Higher levels of circFAM53B predicted poorer survival of glioma patients. Functionally, circFAM53B up-regulation accelerated cell proliferation, colony formation, invasion and epithelial-mesenchymal transition (EMT), and heightened Bax/Bcl2 ratio. By contrast, circFAM53B down-regulation repressed glioma development in vitro. Mechanistically, bioinformatics analysis suggested that circFAM53B served as a competitive endogenous RNA (ceRNA) by sponging miR-532-3p, which targeted proto-oncogene (MET) and receptor tyrosine kinase (c-MET). miR-532-3p up-regulation delayed glioma development and inactivated the PI3K/AKT axis. Moreover, the treatment of the c-MET inhibitor SGX523, the PI3K inhibitor LY294002, and the Akt inhibitor MK-2206 reduced circFAM53B-mediated oncogenic effects. Conclusively, circFAM53B aggravated glioma progression by up-regulating the c-MET/PI3K/AKT pathway and down-regulating miR-532-3p. Thus, the circFAM53B/miR-532-3p/c-MET/PI3K/AKT axis is a potential treatment target for glioma.

CircRNA_0084927 promotes colorectal cancer progression by regulating miRNA-20b-3p/glutathione S-transferase mu 5 axis

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer and the second most common cause of cancer-related death worldwide. The 5-year survival rate of patients with early-stage CRC could reach 90%, but it is very low in patients with advanced-stage CRC. Recent studies have shown that circular RNAs play important roles in regulating the migration and invasion of CRC cells.

AIM

To elucidate the role of circRNA_0084927 (circ_0084927) in the migration and invasion of CRC cells and its underlying mechanism.

METHODS

Clinical tissue samples and cells were collected, and the expression of circ_0084927 was detected by quantitative polymerase chain reaction (qPCR). The diagnostic performance of circ_0084927 was assessed by receiver operating characteristic curve analysis. The role of circ_0084927 in CRC cell proliferation, migration, and invasion was determined using cell counting kit-8 assay, wound healing assay, and transwell assay, respectively. The regulatory relationship among circ_0084927, miRNA-20b-3p (miR-20b-3p), and glutathione S-transferase mu 5 (GSTM5) was identified using databases, luciferase reporter assay, qPCR, and Western blot analysis. AKT-mTOR signaling was also verified after circ_0084927 knockdown or miR-20b-3p mimic treatment.

RESULTS

The expression of circ_0084927 was significantly increased in CRC tissues and cells, and it was higher in advanced-stage CRC compared with early-stage CRC. The area under the curve (AUC) of circ_0084927 was 0.806 [95% confidence interval (CI): 0.683-0.896]. In addition, the AUC was 0.874 (95%CI: 0.738-0.956) in patients with advanced-stage CRC and 0.713 (95%CI: 0.555-0.840) in those with early-stage CRC. Knockdown of circ_0084927 inhibited the migration and invasion of HCT116 cells. Moreover, circ_0084927 was found to act as a sponge of miR-20b-3p. MiR-20b-3p activation reduced the circ_0084927 level, whereas miR-20b-3p inhibition increased the circ_0084927 level. But the effect was not found after circ_0084927 mutation. In addition, miR-20b-3p expression in CRC patients was also reduced and negatively correlated with circ_0084927 expression. The function of circ_0084927 in HCT116 cells with circ_0084927 knockdown was rescued by miR-20b-3p. Moreover, GSTM5 expression was significantly decreased after overexpressing miR-20b-3p or inhibiting circ_0084927, but its expression was rescued when circ_0084927 and miR-20b-3p were both inhibited. Finally, AKT-mTOR signaling was markedly regulated by circ_0084927 and miR-20b-3p.

CONCLUSION

The expression of circ_0084927 is significantly increased in CRC and higher in advanced-stage CRC than in early-stage CRC. Moreover, circ_0084927 potentially regulates CRC cell migration and invasion via the miR-20b-3p/GSTM5/ AKT/mTOR pathway.

The Potential of circRNA as a Novel Diagnostic Biomarker in Cervical Cancer

Cervical cancer is the fourth most common cancer among females worldwide. In spite of advances in detection and treatment, it is still one of the most dangerous gynecological malignancies in the world, especially in developing countries, and seriously threatens human health. Circular RNA (circRNA) is a special new type of endogenous noncoding RNA discovered recently. They form a covalently closed continuous loop and are specifically expressed in the eukaryotic transcriptome. With further understanding of circular RNA, a large number of studies have determined the key regulatory role of circRNA in a variety of diseases, especially cancer (including cervical cancer, liver cancer, and lung cancer). In addition, it has also been found that the abnormal expression of circRNA is related to its pathological characteristics in cervical cancer tissue, which can be used as a potential indicator for early screening and diagnosis of cervical cancer, targeted therapy, and prognosis prediction. This article summarizes the recent research achievements of circRNAs in cervical cancer. We briefly described the abnormal expression of circRNA in cervical cancer and discussed the involvement of circRNA in the occurrence process of cervical cancer by regulating cell proliferation, migration, invasion, and apoptosis. We believe that circRNA has potential value as a biomarker in the diagnosis and prognosis of cervical cancer.

Circ_0020123 Increases ZFX Expression to Facilitate Non-Small Cell Lung Cancer Progression by Sponging miR-142-3p

Background

Circular RNA (circRNA) is involved in the progression of various cancers and has been shown to be an important potential target for cancer therapy. Circ_0020123 has been found to act as oncogene to participate in the malignant progression of non-small cell lung cancer (NSCLC). Therefore, exploring new mechanisms of circ_0020123 regulating NSCLC progression will help us better understand its role in NSCLC.

Methods

Relative expression levels of circ_0020123, microRNA (miR)-142-3p, and zinc-finger protein X-linked (ZFX) in tissues and cells were determined by quantitative real-time PCR (qRT-PCR). Cell proliferation, apoptosis, migration and invasion were assessed using cell counting kit 8 (CCK8) assay, colony formation assay, flow cytometry and transwell assay. Western blot (WB) analysis was used to detect relative protein level. Besides, the interaction between miR-142-3p and circ_0020123 or ZFX was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay.

Results

Our results showed that circ_0020123 was upregulated in NSCLC, and its knockdown could suppress NSCLC cell proliferation, migration, invasion, and promote apoptosis. Circ_0020123 was found to interact with miR-142-3p. The inhibition effect of circ_0020123 silencing on NSCLC progression could be reversed by miR-142-3p inhibitor. ZFX could be targeted by miR-142-3p. The silencing of ZFX could hinder the progression of NSCLC and abolish the promotion effect of miR-142-3p inhibitor on NSCLC progression. In addition, circ_0020123 silencing inhibited NSCLC tumorigenesis by the miR-142-3p/ZFX axis.

Conclusion

These findings suggested that circ_0020123 might be a potential therapy target for NSCLC, which could promote NSCLC progression through regulating the miR-142-3p/ZFX axis.