Cyclin F Controls Cell-Cycle Transcriptional Outputs by Directing the Degradation of the Three Activator E2Fs.

E2F1, E2F2, and E2F3A, the three activators of the E2F family of transcription factors, are key regulators of the G1/S transition, promoting transcription of hundreds of genes critical for cell-cycle progression. We found that during late S and in G2, the degradation of all three activator E2Fs is controlled by cyclin F, the substrate receptor of 1 of 69 human SCF ubiquitin ligase complexes. E2F1, E2F2, and E2F3A interact with the cyclin box of cyclin F via their conserved N-terminal cyclin binding motifs. In the short term, E2F mutants unable to bind cyclin F remain stable throughout the cell cycle, induce unscheduled transcription in G2 and mitosis, and promote faster entry into the next S phase. However, in the long term, they impair cell fitness. We propose that by restricting E2F activity to the S phase, cyclin F controls one of the main and most critical transcriptional engines of the cell cycle.

E2F3-dependent activation of FAM111B restricts mouse cytomegalovirus replication in primate cells.

Cytomegaloviruses are highly species-specific as they replicate only in cells of their own or a closely related species. For instance, human cytomegalovirus cannot replicate in rodent cells, and mouse cytomegalovirus (MCMV) cannot replicate in human and monkey cells. However, the mechanisms underlying the host species restriction remain poorly understood. We have previously shown that passaging MCMV in human retinal pigment epithelial cells allows the virus to replicate to high titers in these cells due to the accumulation of adaptive mutations, such as loss-of-function mutations in the viral M117 gene. The M117 protein interacts with E2F transcription factors and activates E2F-dependent transcription. Here, we show that activation of E2F3 is primarily responsible for MCMV's inability to replicate in human cells. By transcriptome analysis, we identified two E2F3-induced serine proteases, FAM111A and FAM111B, as potential host restriction factors. By using shRNA-mediated gene knockdown and CRISPR/Cas9-mediated gene knockout, we demonstrated that FAM111B, but not its paralog FAM111A, suppresses MCMV replication in human and rhesus macaque cells. By immunofluorescence, we detected FAM111B predominantly in the nucleus of infected cells with enrichment in viral replication compartments, suggesting that it might play a role during viral replication. The fact that the FAM111B gene is conserved in primates but absent in rodents suggests that MCMV has not evolved to evade or counteract this restriction factor, which is not present in its natural host. IMPORTANCE: Viruses must counteract host cell defenses to facilitate viral replication. Viruses with a narrow host range, such as the cytomegaloviruses, are unable to counteract cellular defenses in cells of a foreign species. However, little is known about the cellular host range factors restricting cytomegalovirus replication. Here, we show that mouse cytomegalovirus (MCMV) induces the expression of the FAM111 proteases and that FAM111B, but not FAM111A that has previously been shown to restrict the replication of polyomavirus and orthopoxvirus host range mutants, acts as a cellular factor suppressing MCMV replication in human and rhesus monkey cells. The identification of FAM111B as a host range factor should provide new insight into the physiological functions of this poorly characterized protein.

FTO promotes the progression of retinoblastoma through YTHDF2-dependent N6-methyladenosine modification in E2F3.

Early treatment of retinoblastoma (RB) has significantly improved clinical outcomes. N6-methyladenosine (m6A) methylation is crucial for cancer progression. Thus, we investigated the role of FTO-dependent demethylation in RB and its underlying mechanisms. The biological behavior of RB cells was analyzed using cell counting kit-8, colony formation analysis, transwell assay, flow cytometry, and western blot analysis. m6A modification was evaluated using methylated RNA immunoprecipitation and dual-luciferase reporter assays, and E2F3 stability was assessed using Actinomycin D. The roles of FTO and E2F3 were also elucidated in vivo. These results indicated that FTO was highly expressed in RB cells with low m6A levels. FTO knockdown inhibited RB cell growth, migration, invasion, and epithelial-mesenchymal transition and arrested the cell cycle at the G0/G1 phase. Mechanistically, FTO interference promoted m6A methylation of E2F3, which was recognized by YTHDF2, thereby reducing mRNA stability. E2F3 overexpression partially rescued the effects of FTO knockdown on biological behavior. Moreover, FTO knockdown reduced tumor weight, tumor volume, ki67 expression, and tumor cell infiltration by mediating E2F3. Taken together, FTO silencing inhibited the malignant processes of RB by suppressing E2F3 in an m6A-YTHD2-dependent manner. These findings suggest that FTO is a novel therapeutic target for RB.

Transcription factor E2F3 activates CDC25B to regulate DNA damage and promote mitoxantrone resistance in stomach adenocarcinoma.

BACKGROUND: CDC25B, as a member of the cell cycle regulating protein family, is located in the cytoplasm and is involved in the transition of the cell cycle and mitosis. CDC25B is highly expressed in various tumors and is a newly discovered oncogene. This study aimed to investigate the impact of CDC25B on mitoxantrone resistance in stomach adenocarcinoma (STAD) and its possible mechanisms. METHODS: This study analyzed the expression of CDC25B and its potential transcription factor E2F3 in STAD, as well as the IC50 values of tumor tissues by bioinformatics analysis. Expression levels of CDC25B and E2F3 in STAD cells were measured by qRT-PCR. MTT was utilized to evaluate cell viability and IC50 values of STAD cells, and comet assay was utilized to analyze the level of DNA damage in STAD cells. Western blot was used to analyze the expression of DNA damage-related proteins. The targeting relationship between E2F3 and CDC25B was validated by dual-luciferase and ChIP assays. RESULTS: Bioinformatics analysis and molecular experiments showed that CDC25B and E2F3 were highly expressed in STAD, and CDC25B was enriched in the mismatch repair and nucleotide excision repair pathways. The IC50 values of tumor tissues with high expression of CDC25B were relatively high. Dual-luciferase and ChIP assays confirmed that CDC25B could be transcriptionally activated by E2F3. Cell experiments revealed that CDC25B promoted mitoxantrone resistance in STAD cells by regulating DNA damage. Further research found that low expression of E2F3 inhibited mitoxantrone resistance in STAD cells by DNA damage, but overexpression of CDC25B reversed the impact of E2F3 knockdown on mitoxantrone resistance in STAD cells. CONCLUSION: This study confirmed a novel mechanism by which E2F3/CDC25B mediated DNA damage to promote mitoxantrone resistance in STAD cells, providing a new therapeutic target for STAD treatment.

Circ_001422 aggravates osteosarcoma progression through targeting miR-497-5p/E2F3 axis.

Circular RNAs exert vital functions in the pathogenesis of osteosarcoma (OS). Circ_001422 has been confirmed to be involved in regulating OS progression, but its specific mechanism has not been clearly studied. This work aimed to analyze circ_001422's role in OS cell biological behaviors and the possible molecular mechanisms. This work carried out reverse transcription-quantitative polymerase chain reaction for detecting circ_001422, E2F3 and miR-497-5p levels, whereas Cell counting kit-8 together with Transwell assays for measuring cell growth, migration as well as invasion abilities. Relation of miR-497-5p with E2F3, as well as circ_001422 with miR-497-5p was analyzed through dual-luciferase reporter gene assay. Protein level was identified by western blot. According to our results, circ_001422 expression within OS tissue significantly increased compared with corresponding healthy samples. Inhibition of circ_001422 significantly decreased OS cell growth, invasion and migration. From mechanism research, miR-497-5p was proved as circ_001422's target, and E2F3 was miR-497-5p's target. Besides, miR-497-5p downregulation or E2F3 overexpression abolished circ_001422 inhibition-mediated inhibition on OS cell proliferation, invasion and migration. Collectively, this study has first suggested circ_001422's role in enhancing OS proliferation, migration as well as invasion via miR-497-5p/E2F3 axis. Our results will offer new ideas and new anti-OS targets.

MiR-210-3p enhances intermittent hypoxia-induced tumor progression via inhibition of E2F3.

PURPOSE: Intermittent hypoxia (IH) is a hallmark of obstructive sleep apnea (OSA), which is related to tumorigenesis and progression. Although micro-ribonucleic acid-210-3p (miR-210-3p) is correlated with hypoxia-induced tumor development, its role in the relationship between IH and tumor function remains poorly understood. The present work focused on elucidating the molecular mechanism through which miR-210-3p drives tumor progression under IH. METHODS: MiR-210-3p levels were quantified within tumor samples from patients with lung adenocarcinoma who had or did not have OSA. Correlations between miR-210-3p and polysomnographic variables were analyzed. For in vitro experiments, miR-210-3p was inhibited or overexpressed via transfection under IH conditions. Cell viability, growth, invasion and migration assays were carried out. For in vivo modeling of IH using mouse xenografts, a miR-210-3p antagomir was intratumorally injected, tumor biological behaviors were evaluated, and reverse transcription-quantitative polymerase chain reaction (RT-qPCR), immunohistochemistry and western blot were carried out for detecting miR-210-3p and E2F transcription factor 3 (E2F3) expression. RESULTS: For patients with lung adenocarcinoma and OSA, high miR-210-3p levels showed positive relation to polysomnographic variables, such as oxygen desaturation index, apnea-hypopnea index, and proportion of total sleep time with oxygen saturation in arterial blood < 90%. IH enhanced tumor viability, proliferation, migration, and invasion, downregulated E2F3 expression, and increased miR-210-3-p levels. miR-210-3p overexpression induced similar changes. These changes were reversed by miR-210-3p inhibition in vitro or miR-210-3p antagomir through intratumoral injection in vivo. CONCLUSIONS: IH-induced tumor development is driven through miR-210-3p by E2F3 suppression. MiR-210-3p represents a potential therapeutic target among patients with concomitant cancer and OSA.

Long noncoding RNA plasmacytoma variant translocation 1 promotes progression of colorectal cancer by sponging microRNA-152-3p and regulating E2F3/MAPK8 signaling.

The purpose of this study was to investigate the pathogenesis of colorectal cancer (CRC) and the effects of the long noncoding RNA plasmacytoma variant translocation 1 (PVT1) on CRC progression. Bioinformatics analysis verified PVT1 expression in tumor and normal tissues. Quantitative PCR and western blotting were used to measure mRNA and protein levels, respectively. The MTT, Transwell, colony formation, and in vivo assays were used to assess the effects of PVT1 on proliferation, migration, and invasion by CRC cells. Both PVT1 and microRNA (miR)-152-3p were shown to be colocalized in CRC cells using FISH assay. The target genes of miR-152-3p were predicted and verified by bioinformatics analysis, luciferase assay, and RNA pull-down assay. The ChIP assay revealed that E2F3 binds with the promoter of MAPK8. We found that PVT1 was overexpressed in CRC specimens, and its expression was higher in CRC cells than normal intestinal cells. Overexpression of PVT1 enhanced the proliferation, migration, and invasion of CRC cells, whereas PVT1 knockdown inhibited these processes. MicroRNA-152-3p was a target of PVT1, and E2F3 was a target of miR-152-3p. Rescue experiments confirmed the interaction between miR-152-3p and PVT1 and between miR-152-3p and E2F3. Luciferase and ChIP assay results confirmed that E2F3 modulates the transcriptional activation of MAPK8. Long noncoding RNA PVT1 activated E2F3 signaling by sponging miR-152-3p. The PVT1/miR-152-3p/E2F3/MAPK8 axis promoted CRC progression.

E2F3 gene expression is a potential negative prognostic marker for localised and MYCN not-amplified neuroblastoma: Results of in silico analysis of 786 samples.

BACKGROUND: Neuroblastoma (NB) is an enigmatic childhood malignancy characterised by a wide range of clinical behaviour. Many potential oncogenes for NB have recently been identified. Among them, E2 transcription factor 3 (E2F3) expression was associated with a poor survival in 134 stage 4S patients, but evidence for other stage groups remains poorly investigated. METHODS: We have analysed the expression of E2F3 gene from a database of 786 NB samples. Overall and event-free survivals (EFS) were assessed by the Kaplan-Meier method, splitting the data on the median and tertile expression values. The Cox model was applied to control for the confounding by stage, age and MYCN amplification. Validation was performed by an in silico analysis of an independent cohort of 283 NB patients. Furthermore, an immunofluorescence analysis on 48 formalin-fixed, paraffin-embedded NB specimens was also performed. RESULTS: E2F3 overexpression was associated with a poor survival (EFS = 84%, 95% CI: 79%-95%, for low expression levels; EFS = 62%, 95% CI: 56%-68% for middle levels; EFS = 30%, 95% CI: 24%-36%, for high levels, p < .001). This association was confirmed in multivariable analysis and was more evident in patients with MYCN not-amplified and localised stages. Immunofluorescence results and the validation on an independent cohort of NB primary samples confirmed these findings. CONCLUSIONS: E2F3 is a new potential prognostic marker in NB with favourable characteristics at diagnosis. Further studies are needed to elucidate the potential role of E2F3 in NB oncogenesis and progression, in order to identify new targets for therapeutic interventions.

Long Non-coding RNA FOXD2-AS1 Promotes Proliferation, Migration, and Invasion in Cholangiocarcinoma Through Regulating miR-760/E2F3 Axis.

BACKGROUND: Long non-coding RNA (lncRNA) has been testified to influence the initiation and evolution of sundry carcinomas. Recently, lncRNA FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1) has been found to display vital regulating functions in various cancers. METHODS: qRT-PCR was used to verify the dysregulation of FOXD2-AS1 expression in CCA cells and tissues, and the correlation of FOXD2-AS1 expression with clinicopathological characteristics was investigated. The viability, migration, and invasion of CCA cells were verified through CCK-8 assay, colony formation experiment, wound healing assay, and transwell assay. The regulatory networks of FOXD2-AS1 were analyzed by Bioinformatic prediction and dual-luciferase reporter assay. RESULTS: We discovered that FOXD2-AS1 was significantly upregulated in CCA and its up-regulation was closely correlated with terminal TNM stage, lymph node metastasis and poor survival in the current research. In addition, it was revealed that FOXD2-AS1 was an independent prognostic factor. Functional tests uncovered that the cell viability, migration, and invasion could be restrained through downregulating the expression of FOXD2-AS1, while FOXD2-AS1 overexpression could facilitate the cell viability, migration, and invasion. Mechanistically, FOXD2-AS1 was founded to interact directly with miR-760 and the oncogene E2F3 was the downstream target of miR-760 through bioinformatic prediction and dual-luciferase reporter assays. Finally, we testified that FOXD2-AS1 could competitively sponge miR-760 and further upregulated the E2F3 expression to play a vital part in cholangiocarcinoma. CONCLUSIONS: This research revealed that lncRNA FOXD2-AS1 could enhance CCA malignant progression through regulating the miR-760/E2F3 axis and was expected to be a prognostic biomarker and therapeutic target for cholangiocarcinoma.

Prognostic analysis of E2F transcription factors E2F1 and E2F3 in four independent pediatric neuroblastoma cohorts.

BACKGROUND: Previously, we had analyzed the prognosis of E2F transcription factors across adult tumor types. However, the expressions and prognosis of E2F transcription factors in pediatric neuroblastoma have not yet been fully studied. METHODS: The prognosis of E2F transcription factors was determined in four independent pediatric neuroblastoma cohorts from Therapeutically Applicable Research to Generate Effective Treatments (TARGET), Gene Expression Omnibus (GEO) and European ArrayExpres datasets using Kaplan-Meier and cox regression analysis. RESULTS: E2F regulated gene set was associated with the event free survival and the overall survival of neuroblastoma. E2F1 and E2F3 were prognostic factors in all four independent pediatric neuroblastoma cohorts. Over-expressions of E2F1 or E2F3 were correlated with the shorted event free survival and overall survival of neuroblastoma. Expression levels of E2F1 and E2F3 were higher in neuroblastoma patients with MYCN amplification or age at diagnosis ≥ 18 months. Moreover, the prognostic significance of E2F1 or E2F3 in neuroblastoma was independent of MYCN amplification and age of diagnosis. Combinations of E2F1, E2F3 with MYCN amplification or age of diagnosis achieved better prognosis of neuroblastoma. Identification of 234 genes were associated with E2F1 and E2F3 expressions in neuroblastoma and those genes were significantly enriched in cell cycle signaling pathway. Also, higher scores of cell cycle signaling pathway were correlated with the adverse prognosis of neuroblastoma. CONCLUSIONS: E2F transcription factors E2F1 and E2F3 were prognostic makers of neuroblastoma.

Hsa_hsa_circ_0081069 promotes the progression of colorectal cancer through sponging miR-665 and regulating E2F3 expression.

BACKGROUND: Circular RNAs (circRNAs) have been implicated in the initiation and development of various cancers. This study explored the potential contribution of hsa_hsa_circ_0081069 in the progression of colorectal cancer (CRC). METHODS: The gene expression was analyzed by qRT-PCR. Functional roles of hsa_circ_0081069 were examined by shRNA-mediated silencing using CCK-8 proliferation assay, Transwell migration and invasion assay, tube formation assay. The tumorigenesis and metastasis of CRC cells were assess in a xenograft mouse model. RESULTS: Hsa_circ_0081069 was significantly upregulated in CRC tissues and cells. Hsa_circ_0081069 knockdown suppressed the proliferation, migration and invasion in CRC cells, as well as the angiogenesis. Silencing hsa_circ_0081069 also impaired the tumorigenesis of CRC cells in a xenograft mouse model. Furthermore, miR-665 was identified as an interacting partner of hsa_circ_0081069, which was negatively regulated by hsa_circ_0081069. miR-665 targeted the mRNA of E2F3 to suppress its expression. We further demonsatred that miR-665/E2F3 axis mediated the functional role of hsa_circ_0081069 in regulating the malignant phenotype of CRC cells. CONCLUSIONS: Collectively, our study suggests that hsa_circ_0081069 could serve as a prognostic marker in progression of CRC. Targeting hsa_circ_0081069 and miR-665/E2F3 axis could serve as potential therapeutic strategies for CRC treatment.

Long noncoding RNA MAPKAPK5-AS1 promoted lipopolysaccharide-induced inflammatory damage in the myocardium by sponging microRNA-124-3p/E2F3.

BACKGROUND: Myocardial dysfunction caused by sepsis (SIMD) leads to high mortality in critically ill patients. We investigated the function and mechanism of long non-coding RNA MAPKAPK5-AS1 (lncRNA MAPKAPK-AS1) on lipopolysaccharide (LPS)-induced inflammation response in vivo and in vitro. METHOD: Male SD rats were utilized for in vivo experiments. Rat cardiomyocytes (H9C2) were employed for in vitro experiments. Western blotting was employed to measure protein expression, and RT-PCR was performed to measure mRNA expression of inflammation factors. TUNEL and flow cytometry were carried out to evulate cell apoptosis. RESULT: The results showed that the expression of MAPKAPK5-AS1 was increased, while the expression of miR-124-3p was decreased in the inflammatory damage induced by LPS in vivo and in vitro. Knockdown of MAPKAPK5-AS1 reduced LPS-induced cell apoptosis and inflammation response, while overexpression of miR-124-3p weakened the effects of MAPKAPK5-AS1 knockdown on LPS-induced cell apoptosis and inflammation response. Moreover, miR-124-3p was identified as a downstream miRNA of MAPKAPK5-AS1, and E2F3 was a target of miR-214-3p. MAPKAPK5-AS1 knockdown increased the expression of miR-124-3p, while miR-124-3p overexpression reduced the expression of MAPKAPK5-AS1. In addition, miR-124-3p was found to downregulate E2F3 expression in H9C2 cells. CONCLUSION: MAPKAPK5-AS1/miR-124-3p/E2F3 axis regulates LPS-related H9C2 cell apoptosis and inflammatory response.

Retinoblastoma protein represses E2F3 to maintain Sertoli cell quiescence in mouse testis.

Maintenance of the differentiated state and cell cycle exit in adult Sertoli cells depends on tumor suppressor retinoblastoma protein (RB, also known as RB1). We have previously shown that RB interacts with transcription factor E2F3 in the mouse testis. Here, we investigated how E2f3 contributes to adult Sertoli cell proliferation in a mouse model of Sertoli cell-specific knockout of Rb by crossing these mice with an E2f3 knockout mouse line. In the presence of intact RB, E2f3 was redundant in Sertoli cells. However, in the absence of RB, E2f3 is a key driver for cell cycle re-entry and loss of function in adult Sertoli cells. Knockout of E2f3 in Sertoli cells rescued the breakdown of Sertoli cell function associated with Rb loss, prevented proliferation of adult Sertoli cells and restored fertility of the mice. In summary, our results show that RB-mediated repression of E2F3 is critical for the maintenance of cell cycle exit and terminal differentiation in adult mouse Sertoli cells.

Circular RNA circZNF292 regulates H2 O2 -induced injury in human lens epithelial HLE-B3 cells depending on the regulation of the miR-222-3p/E2F3 axis.

Circular RNAs (circRNAs) play important roles in the pathogenesis of age-related cataract (ARC). CircRNA zinc finger protein 292 (circZNF292, hsa_circ_0004058) is downregulated in ARC lens capsules. Here, we focused on its precise roles in oxidative stress underlying the pathogenesis of ARC. CircZNF292, microRNA (miR)-222-3p, and E2F transcription factor 3 (E2F3) were quantified by quantitative real-time polymerase chain reaction or western blot. Cell viability was assessed by the cell counting kit-8 assay. Cell cycle distribution and apoptosis were detected by flow cytometry. The activities of superoxide dismutase, catalase, and malondialdehyde were measured using the corresponding assay kit. Targeted correlations among circZNF292, miR-222-3p, and E2F3 were verified by the dual-luciferase reporter, RNA immunoprecipitation and RNA pull-down assays. Our data showed that circZNF292 was downregulated in ARC tissues and H2 O2 -treated human lens epithelial B3 (HLE-B3) cells. Increased expression of circZNF292 alleviated H2 O2 -induced cell viability suppression, apoptosis promotion, and oxidative stress enhancement. Mechanistically, circZNF292 directly targeted miR-222-3p, and circZNF292 regulated E2F3 expression through miR-222-3p. MiR-222-3p was a functional mediator of circZNF292 in modulating H2 O2 -induced injury in HLE-B3 cells. Furthermore, reduced level of miR-222-3p ameliorated H2 O2 -induced HLE-B3 cell damage by upregulating E2F3. Our present study demonstrated that increased expression of circZNF292 ameliorated H2 O2 -induced injury in HLE-B3 cells at least in part through the miR-222-3p/E2F3 axis, highlighting a novel insight into the involvement of circRNAs in the pathogenesis of ARC.

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.

H3K27ac-induced FOXC2-AS1 accelerates tongue squamous cell carcinoma by upregulating E2F3.

BACKGROUND: The important roles of lncRNAs have been reported in cancers, including tongue squamous cell carcinoma (TSCC). Here, we investigated the functional role and molecular mechanisms of lncRNA FOXC2-AS1 in TSCC. METHODS: The expression level of FOXC2-AS1 in TSCC was determined by RT-qPCR. Its biological role was evaluated through colony formation assay, flow cytometry, wound healing, transwell, and Western blot analyses. The interactions among gene were tested by mechanistic investigations. RESULTS: FOXC2-AS1 expression was high in TSCC tissues and cells. Functional assays in vitro showed that silencing FOXC2-AS1 restrained cell proliferation, cell cycle, migration, invasion, and EMT. In the mechanism, it was verified that H3K27 acetylation (H3K27ac) triggered an increase in FOXC2-AS1 expression. Furthermore, FOXC2-AS1 was identified as a cytoplasmic lncRNA and served as a ceRNA to upregulate E2F3 expression via sponging miR-6868-5p. CONCLUSION: H3K27ac-induced FOXC2-AS1 exhibits carcinogenic property in TSCC by the miR-6868-5p/E2F3 axis.

Circ_PGPEP1 Serves as a Sponge of miR-1297 to Promote Gastric Cancer Progression via Regulating E2F3.

BACKGROUND: Circular RNA (circRNA) is a special kind of noncoding RNA that plays a vital function in the progression of gastric cancer (GC). However, the role of a new circRNA, circ_PGPEP1, in GC is unclear. AIMS: Exploring the role and mechanism of circ_PGPEP1 in GC progression. METHODS: The expression levels of circ_PGPEP1, miR-1297, and E2F transcription factor 3 (E2F3) were determined using quantitative real-time PCR. Flow cytometry, colony formation assay, MTT assay, and transwell assay were used to evaluate cell cycle, apoptosis, proliferation, migration, and invasion. The protein levels of apoptosis-related markers and E2F3 were measured by western blot analysis. The interaction between circ_PGPEP1 and miR-1297 or miR-1297 and E2F3 was confirmed by dual-luciferase reporter assay. In addition, animal experiments were performed to assess the effect of circ_PGPEP1 on GC tumor growth in vivo. RESULTS: Circ_PGPEP1 was a highly expressed circRNA in GC. Loss-of-function experiment indicated that circ_PGPEP1 silencing could induce cell cycle arrest and apoptosis, while inhibit proliferation, migration, and invasion in GC cells. MiR-1297 could be sponged by circ_PGPEP1, and its expression was downregulated in GC. MiR-1297 inhibitor could reverse the negatively regulation of circ_PGPEP1 knockdown on GC progression. Furthermore, we also found that E2F3 could be targeted by miR-1297, and its expression was positively regulated by circ_PGPEP1. Overexpression of E2F3 could invert the inhibitory effect of miR-1297 on GC progression. Animal experiments suggested that silenced circ_PGPEP1 could reduce GC tumor growth. CONCLUSION: Our research showed that circ_PGPEP1 might serve as a potential biomarker for GC.

Epstein-Barr Virus miR-BART1-3p Regulates the miR-17-92 Cluster by Targeting E2F3.

Epstein-Barr virus (EBV) is associated with several tumors and generates BamHI A rightward transcript (BART) microRNAs (miRNAs) from BART transcript introns. These BART miRNAs are expressed at higher levels in EBV-associated epithelial malignancies than in EBV-infected B lymphomas. To test the effects of EBV miRNA on the cell cycle and cell growth, we transfected miR-BART1-3p, a highly expressed EBV-associated miRNA, into gastric carcinoma cells. We found that miR-BART1-3p induced G0/G1 arrest and suppressed cell growth in gastric carcinoma cells. As our microarray analyses showed that E2F3, a cell cycle regulator, was inhibited by EBV infection, we hypothesized that miR-BART1-3p regulates E2F3. Luciferase assays revealed that miR-BART1-3p directly targeted the 3'-UTR of E2F3 mRNA. Both E2F3 mRNA and encoded protein levels were reduced following miR-BART1-3p transfection. In contrast, E2F3 expression in AGS-EBV cells transfected with a miR-BART1-3p inhibitor was enhanced. As E2F3 has been shown to regulate the expression of highly conserved miR-17-92 clusters in vertebrates, we examined whether this expression is affected by miR-BART1-3p, which can downregulate E2F3. The expression of E2F3, miR-17-92a-1 cluster host gene (MIR17HG), and miR-17-92 cluster miRNAs was significantly reduced in EBV-associated gastric carcinoma (EBVaGC) patients compared with EBV-negative gastric carcinoma (EBVnGC) patients. Further, miR-BART1-3p as well as the siRNA specific to E2F3 inhibited the expression of the miR-17-92 cluster, while inhibition of miR-BART1-3p enhanced the expression of the miR-17-92 cluster in cultured GC cells. Our results suggest a possible role of miR-BART1-3p in cell cycle regulation and in regulation of the miR-17-92 cluster through E2F3 suppression.

Loss of lncRNA MIAT ameliorates proliferation and fibrosis of diabetic nephropathy through reducing E2F3 expression.

Diabetic nephropathy (DN) is a serious kidney disease resulted from diabetes. Dys-regulated proliferation and extracellular matrix (ECM) accumulation in mesangial cells contribute to DN progression. In this study, we tested expression level of MIAT in DN patients and mesangial cells treated by high glucose (HG). Up-regulation of MIAT was observed in DN. Then, functional assays displayed that silence of MIAT by siRNA significantly repressed the proliferation and cycle progression in mesangial cells induced by HG. Meanwhile, we found that collagen IV, fibronectin and TGF-ß1 protein expression was obviously triggered by HG, which could be rescued by loss of MIAT. Then, further assessment indicated that MIAT served as sponge harbouring miR-147a. Moreover, miR-147a was decreased in DN, which exhibited an antagonistic effect of MIAT on modulating mesangial cell proliferation and fibrosis. Moreover, bioinformatics analysis displayed that E2F transcription factor 3 (E2F3) could act as direct target of miR-147a. We demonstrated that E2F3 was greatly increased in DN and the direct binding association between miR-147a and E2F3 was evidenced using luciferase reporter assay. In summary, our data explored the underlying mechanism of DN pathogenesis validated that MIAT induced mesangial cell proliferation and fibrosis via sponging miR-147a and regulating E2F3.

CircPRMT5 circular RNA promotes proliferation of colorectal cancer through sponging miR-377 to induce E2F3 expression.

CircPRTM5 is associated with cell proliferation and migration in many kinds of malignancies. However, the functions and mechanisms of CircPRTM5 in CRC progression remain unclear. We explored the role and the mechanisms of CircPRTM5 in the development of CRC. Tissues of CRC patients and matched adjacent non-tumour tissues were collected to evaluate the expression of CircPRTM5. The expression of CircPRTM5 in CRC tissues was significantly higher than that in adjacent tissues. The biological functions of CircPRTM5 in CRC were determined by overexpression and down-regulation of CircPRTM5 in CRC cells in vitro and in vivo. The results indicate that knockdown of CircPRTM5 can significantly inhibit the proliferation of CRC cells. The potential mechanisms of CircPRTM5 in CRC development were identified by RT-qPCR, Western blotting analysis and luciferase reporter assay. CircPRTM5 competitively regulates the expression of E2F3 by capillary adsorption of miR-377. CircPRMT5 regulates CRC proliferation by regulating the expression of E2F3, which affects the expression of the cell cycle-associated proteins cyclinD1 and CDK2. CircPRTM5 exerts critical regulatory role in CRC progression by sponging miR-377 to induce E2F3 expression.