Knockdown of RNA-binding protein IMP3 suppresses oral squamous cell carcinoma proliferation by destabilizing E2F5 transcript.

The expression level of RNA-binding proteins (RBPs) is dysregulated in oral squamous cell carcinoma (OSCC) and other types of cancer. Among the RBPs, IMP3 is involved in the progression of OSCC. However, the regulation of mRNA fate by IMP3 in OSCC remains less understood. We analyzed the expression level of IMP3 and E2F5 in OSCC tissues and cell lines by immunohistochemistry, qRT-PCR and Western blot. Subsequently, to further investigate the effect of IMP3 on E2F5 expression, we used siRNAs to silence IMP3 expression in OSCC cell lines SCC-25 and SCC-4. The binding site of E2F5 mRNA and IMP3 was confirmed by RNA immunoprecipitation (RIP). Finally, the function of IMP3 and E2F5 was investigated in viro and in xenograft mouse models. Here we report a positive correlation between IMP3 and E2F5 expression in OSCC, which are involved in cell proliferation and cell cycle. Mechanistically, E2F5 mRNA is bound by IMP3 protein, and silencing it leads to a shortened mRNA half-life and reduced protein expression. Also, knockdown of IMP3 inhibited allograft tumor progression in vivo. These studies reveal the molecular mechanism by which IMP3 regulates E2F5 mRNA stability and identify IMP3/E2F5 as a potential therapeutic target in OSCC.

E2F5 Targeted by Let-7d-5p Facilitates Cell Proliferation, Metastasis and Immune Escape in Gallbladder Cancer.

BACKGROUND: Gallbladder cancer (GBC) remains a serious cause of cancer-related mortality across the globe. E2F5 has been identified to as a known oncogene in various cancers. However, the special functions of E2F5 have not been investigated in GBC. AIMS: To explore the regulatory functions of E2F5 and its related molecular regulatory mechanism in GBC progression. METHODS: The expression of genes were examined through qRT-PCR, western blot and IHC assay. The cell proliferation was assessed through CCK-8 and EDU assays. The cytotoxicity was tested through LDH assay. The percentage of CD8+ T cells and cell apoptosis were evaluated through flow cytometry. The binding ability was detected through luciferase reporter assay. The tumor growth was assessed through in vivo assays. RESULTS: In this study, it was demonstrated that E2F5 expression was evaluated in GBC, and resulted into poor prognosis. Bioinformatics analysis revealed E2F5 as a target for let-7d-5p, which when overexpressed, suppressed the metastasis and proliferation of GBC through the downregulation of E2F5. It was discovered that E2F5 activates JAK2/STAT3 signaling which is suppressed by let-7d-5p, implicating this pathway as one of the effectors of the oncogenic effects of ESF5 in GBC. E2F5 had been confirmed to aggravate tumor growth in vivo. CONCLUSION: E2F5 targeted by let-7d-5p facilitated cell proliferation, metastasis and immune escape in GBC through the JAK2/STAT3 pathway.

[Effects of lncRNA SNHG12 on the proliferation, migration and invasiveness of prostate cancer cells by regulating E2F5 expression].

OBJECTIVE: To analyze the effects of lncRNA SNHG12 on the proliferation, migration and invasiveness of PCa cells by regulating the expression of E2F5. METHODS: Using real time fluorescence RT-PCR, we detected the expressions of lncRNA SNHG12 and E2F5, constructed the PC3 cells inhibiting the lncRNA SNHG12 expression. After transfection of the PC3 cells, we divided them into an NC, a si-NC, a si-SNHG12, a si-E2F5, a si-SNHG12+OE-si-NC, and a si-SNHG12+OE-E2F5 group, followed by examination of the proliferation, apoptosis, migration and invasiveness of the cells in different groups. RESULTS: The expressions of lncRNA SNHG12 and E2F5 were significantly up-regulated in the PCa tissue compared with those in the adjacent tissue (P < 0.05), remarkably higher in the DU145, LNCaP and PC3 groups than in the RWPE-1 group, the highest in the PC3 group (P < 0.05). The expression of SNHG12 was markedly down-regulated in the si-SNHG12 group (P < 0.05) in comparison with that in the si-NC group, indicating the successful construction of a PC3 cell line interfering with the lncRNA SNHG12 expression. Compared with the si-NC group, the si-SNHG12 group showed significant decreases in the values of CyclinD1, MMP-9 and OD and the numbers of migrating and invading cells, and an increase in apoptotic cells (P < 0.05), while the si-E2F5 group exhibited a remarkably down-regulated expression of E2F5 (P < 0.05), reduced values of CyclinD1, MMP-9 and OD, decreased numbers of migrating and invading cells and an increased number of apoptotic cells (P < 0.05). The dual luciferase report test showed that E2F5 reduced the luciferase activity of SNHG12 (P < 0.05 and had an insignificant impact on the luciferase activity of MUT-SNHG12 (P > 0.05). Inhibiting the expression of lncRNA SNHG12 resulted in significant decreases in the expression of E2F5, values of CyclinD1, MMP-9 and OD and numbers of migrating and invading cells, but an increase in apoptotic cells (P < 0.05). The E2F5 expression, the CyclinD1, MMP-9 and OD values and the numbers of migrating and invading cells were markedly increased while the number of apoptotic cells decreased in the si-SNHG12+OE-E2F5 group compared with those in the si-SNHG12+OE-si-NC group (P < 0.05). CONCLUSION: Interfering with the expression of lncRNA SNHG12 can regulate that of E2F5, inhibit the proliferation, migration and invasiveness of PCa cells and promote their apoptosis.

LINC01980 induced by TGF-beta promotes hepatocellular carcinoma metastasis via miR-376b-5p/E2F5 axis.

Hepatocellular carcinoma (HCC) is one of the most aggressive human malignancies worldwide. However, the molecular mechanism of HCC metastasis is largely unknown. Long non-coding RNA (lncRNA) plays a key role in gene regulation, and dysregulation of lncRNA is critical to cancer metastasis. LINC01980 has been reported in ESCC recently, but the mechanism underlying its function in HCC is still unknown. In this study, we found that LINC01980 was upregulated and associated with notably poor overall survival in HCC patients. Functionally, LINC01980 played a carcinogenic role and promoted HCC metastasis. Mechanically, LINC01980 enhanced the E2F5 expression via competitively binding miR-376b-5p, thereby inducing epithelial-mesenchymal transition and promoting HCC cells migration and invasion. In addition, LINC01980-mediated HCC cells metastasis was dependent on E2F5. What's more, TGF-ß activated LINC01980 transcription through the canonical TGF-ß/SMAD signaling pathway in HCC. In conclusion, LINC01980, activated by the canonical TGF-ß/SMAD pathway, promoted HCC metastasis via miR-376b-5p/E2F5 axis. Therefore, LINC01980 might be a potential prognostic biomarker and therapeutic target of HCC.

CircFOXM1 promotes the proliferation, migration, invasion, and glutaminolysis of glioblastoma by regulating the miR-577/E2F5 axis.

Circular RNA (circRNA) is a key regulator of tumor progression. However, the role of circFOXM1 in glioblastoma (GBM) progression is unclear. The aim of this study was to investigate the role of circFOXM1 in GBM progression. The expression levels of circFOXM1, miR-577, and E2F transcription factor 5 (E2F5) were examined by real-time quantitative polymerase chain reaction. Cell counting kit 8 assay, EdU staining, and transwell assay were used to detect cell proliferation, migration, and invasion. The levels of glutamine, glutamate, and α-ketoglutarate were determined to evaluate the glutaminolysis ability of cells. Protein expression was tested by Western blot analysis. Dual-luciferase reporter assay, RNA pull-down assay, and RNA immunoprecipitation assay were employed to verify the interaction between miR-577 and circFOXM1 or E2F5. Mice xenograft model for GBM was constructed to perform in vivo experiments. Our results showed that circFOXM1 was highly expressed in GBM tumor tissues and cells. Silencing of cir FOXM1 inhibited GBM cell proliferation, migration, invasion, glutaminolysis, as well as tumor growth. MiR-577 could be sponged by circFOXM1, and its inhibitor could reverse the suppressive effect of circFOXM1 downregulation on GBM progression. E2F5 was a target of miR-577, and the effect of its knockdown on GBM progression was consistent with that of circFOXM1 silencing. CircFOXM1 positively regulated E2F5 expression, while miR-577 negatively regulated E2F5 expression. In conclusion, our data confirmed that circFOXM1 could serve as a sponge of miR-577 to enhance the progression of GBM by targeting E2F5, which revealed that circFOXM1 might be a biomarker for GBM treatment.

E2F5 Promotes the Malignancy of Ovarian Cancer Via the Regulation of Hippo and Wnt Pathways.

Background: E2F5 is a transcription factor that is overexpressed in the early stages of ovarian cancer and has been suggested as a potential biomarker for early detection. In this study, we aimed to examine the role of E2F5 in invasion and proliferation of ovarian cancer cells. Materials and Methods: We performed cell viability, colony formation, and invasion assays using ovarian cancer cells treated with siRNA to knock down the E2F5 gene. The regulatory effects of E2F5 on proteins involved in the apoptotic, Wnt, Hippo, and retinoblastoma signaling pathways were evaluated by western blotting following E2F5 repression. In addition, we analyzed data available on Gene Expression Profiling Interactive Analysis for correlations between E2F5 and YAP, ß-catenin, cyclin D1, cdk4, and caspase-9. Results: E2F5 was highly expressed in ovarian cancer cell lines and samples when compared to the nonmalignant tissues. Downregulation of E2F5 inhibited cell viability and invasion and promoted the phosphorylation of YAP, GSK-3-ß, ß-catenin, and retinoblastoma. However, cyclin D1, cdk4, and caspase-9 were downregulated when compared to control. Conclusion: Overall, E2F5 promotes ovarian carcinogenesis via the regulation of Hippo and Wnt pathways.

Downregulation of long non-coding RNA UCA1 represses tumorigenesis and metastasis of osteosarcoma via miR-513b-5p/E2F5 axis.

Long non-coding RNAs have the regulatory roles in different kinds of human cancers. The key point of this study was to research the functional mechanisms of urothelial carcinoma associated 1 (UCA1) in the development of osteosarcoma. Quantitative real-time PCR was adopted for the expression detection of UCA1, microRNA-513b-5p (miR-513b-5p) and E2F transcription factor 5 (E2F5). The target relation was verified via dual-luciferase reporter assay and RNA pull-down assay. Cell proliferation was evaluated using Cell Counting Kit-8 and colony formation assays. Transwell assay was applied to assess cell migration and invasion. Western blot was performed for protein examination. Xenograft experiment was used to explore the effect of UCA1 on osteosarcoma in vivo. UCA1 expression was enhanced while miR-513b-5p was refrained in osteosarcoma tissues and cells. MiR-513b-5p was a target of UCA1. Inhibition of UCA1 or overexpression of miR-513b-5p suppressed osteosarcoma cell proliferation, migration and invasion. E2F5 was identified as a downstream gene of miR-513b-5p. MiR-513b-5p inhibitor or E2F5 overexpression rescued the progression inhibition of osteosarcoma by UCA1 knockdown, and UCA1 regulated E2F5 and Cyclin E expression by targeting miR-513b-5p. Downregulation of UCA1 restrained the tumorigenesis of osteosarcoma in vivo through the miR-513b-5p/E2F5 axis. Collectively, knockdown of UCA1 inhibited tumorigenesis and metastasis of osteosarcoma via regulating the miR-513b-5p/E2F5 axis. UCA1 might be a biological indicator in the progression and treatment of osteosarcoma.

CDK13 upregulation-induced formation of the positive feedback loop among circCDK13, miR-212-5p/miR-449a and E2F5 contributes to prostate carcinogenesis.

BACKGROUND: Both E2F transcription factor and cyclin-dependent kinases (CDKs), which increase or decrease E2F activity by phosphorylating E2F or its partner, are involved in the control of cell proliferation, and some circRNAs and miRNAs regulate the expression of E2F and CDKs. However, little is known about whether dysregulation among E2Fs, CDKs, circRNAs and miRNAs occurs in human PCa. METHODS: The expression levels of CDK13 in PCa tissues and different cell lines were determined by quantitative real-time PCR and Western blot analysis. In vitro and in vivo assays were preformed to explore the biological effects of CDK13 in PCa cells. Co-immunoprecipitation anlysis coupled with mass spectrometry was used to identify E2F5 interaction with CDK13. A CRISPR-Cas9 complex was used to activate endogenous CDK13 and circCDK13 expression. Furthermore, the mechanism of circCDK13 was investigated by using loss-of-function and gain-of-function assays in vitro and in vivo. RESULTS: Here we show that CDK13 is significantly upregulated in human PCa tissues. CDK13 depletion and overexpression in PCa cells decrease and increase, respectively, cell proliferation, and the pro-proliferation effect of CDK13 is strengthened by its interaction with E2F5. Mechanistically, transcriptional activation of endogenous CDK13, but not the forced expression of CDK13 by its expression vector, remarkably promotes E2F5 protein expression by facilitating circCDK13 formation. Further, the upregulation of E2F5 enhances CDK13 transcription and promotes circCDK13 biogenesis, which in turn sponges miR-212-5p/449a and thus relieves their repression of the E2F5 expression, subsequently leading to the upregulation of E2F5 expression and PCa cell proliferation. CONCLUSIONS: These findings suggest that CDK13 upregulation-induced formation of the positive feedback loop among circCDK13, miR-212-5p/miR-449a and E2F5 is responsible for PCa development. Targeting this newly identified regulatory axis may provide therapeutic benefit against PCa progression and drug resistance.

Knockdown of E2F5 induces cell death via the TP53­dependent pathway in breast cancer cells carrying wild­type TP53.

E2F transcription factor 5 (E2F5) is a member of the E2F family of transcription factors, which are involved in regulation of various cellular processes, including cellular proliferation, apoptosis, differentiation and DNA damage response. Previously, we reported that E2F5 was aberrantly overexpressed in estrogen receptor (ER)­negative breast cancer, especially in triple­negative breast cancer (TNBC). In the present study, it was revealed that E2F5 gene silencing caused a significant reduction in the proliferation rate of breast cancer MCF7 (ER­positive luminal­type) and MDA­MB­231 (TNBC­type) cells. Additional experiments demonstrated that E2F5 knockdown triggered cell death of MCF7 cells but not MDA­MB­231 cells. As MCF7 and MDA­MB­231 cells carry wild­type and mutant TP53, respectively, and BT474 (ER­negative, HER2­positive type) carrying mutant TP53 exhibited similar results to MDA­MB­231, the possible effects of E2F5 gene depletion on cell death­related TP53­target gene expression were examined. Real­time RT­qPCR analysis revealed that knockdown of E2F5 in MCF7 cells stimulated cell death­related transcription of TP53­target genes such as BAX, NOXA and PUMA. For MDA­MB­231 and BT474 cells, E2F5 gene silencing revealed marginal effects on the expression of TP53 target genes. In addition, silencing of TP53 abrogated the effect of E2F5 silencing in MCF7 cells. Collectively, the present results indicated that E2F5 participated in the carcinogenesis of breast cancer carrying wild­type TP53 through suppression of TP53, while E2F5 had a pro­proliferative but not anti­apoptotic effect on breast cancer with TP53 mutation.

E2F5 promotes prostate cancer cell migration and invasion through regulation of TFPI2, MMP-2 and MMP-9.

Previously, our laboratory demonstrated that a deregulated E2F5/p38/SMAD3 axis was associated with uncontrolled cellular proliferation in prostate cancer (PCa). Here, we investigate the role of E2F5 in PCa in further details. RNAi-mediated E2F5 knockdown and pathway-focused gene expression profiling in PC3 cells identified TFPI2 as a downstream target of E2F5. Manipulation of E2F5 expression was also found to alter MMP-2 and MMP-9 levels as detected by Proteome Profiler array, western blot and reverse transcription coupled quantitative polymerase chain reaction Site-directed mutagenesis, dual-luciferase assays and chromatin immunoprecipitation with anti-E2F5-IgG coupled with qPCR confirmed recruitment of E2F5 on TFPI2, MMP-2 and MMP-9 promoters. RNAi-mediated knockdown of E2F5 expression in PC3 caused a significant alteration of cell migration while that of TFFI2 resulted in a modest change. Abrogation of E2F5 and TFPI2 expression was associated with significant changes in the gelatinolytic activity of active forms of MMP-2 and MMP-9. Moreover, E2F5, MMP-2 and MMP-9 levels were elevated in biopsies of PCa patients relative to that of benign hyperplasia, while TFPI2 expression was reduced. MMP-9 was coimmunoprecipitated with anti-TFPI2-IgG in PCa tissue samples suggesting a direct interaction between the proteins. Finally, artemisinin treatment in PC3 cells repressed E2F5 along with MMP-2/MMP-9 while triggering TFPI2 expression which alleviated PC3 aggressiveness possibly through inhibition of MMP activities. Together, our study reinstates an oncogenic role of E2F5 which operates as a dual-function transcription factor for its targets TFPI2, MMP-2 and MMP-9 and promotes cellular invasiveness. This study also indicates a therapeutic potential of artemisinin, a natural compound which acts by correcting dysfunctional E2F5/TFPI2/MMP axis in PCa.

Circular RNA ABCB10 promotes non-small cell lung cancer progression by increasing E2F5 expression through sponging miR-584-5p.

BACKGROUND/AIMS: CircABCB10 function as an endogenous miRNA sponge plays an important role in various tumors. This experimental design was based on circABCB10 to explore the pathogenesis of non-small cell lung cancer (NSCLC). Methods: CircRNA microarray was used to examine circRNA expression profiles in lung cancer from 3 NSCLC patients and paired healthy lung tissues. The expression of circABCB10 and miR-584-5p was detected by q-PCR. CCK-8, colony formation, and transwell assays to study the circABCB10 effects on tumor cell growth and cell migration invasiveness. To validate downstream target genes of circABCB10 and miR-584-5p detected by luciferase reporter assays. RT-qPCR and Western blotting were used to study E2F5 expression. The tumor growth was detected by nude mice in vivo. Results: We analyzed the human circRNA expression profile in NSCLC tissues. CircABCB10 was identified as a circRNA that increased in NSCLC tissues. CircABCB10 was noticeably raised in NSCLC, and high circABCB10 expression was related to low survival in NSCLC patients. Silencing of circABCB10 suppressed non-small cell lung cancer cell migration, cell proliferation, and invasion.CircABCB10 can act as a sponge of miR-584-5p to up-regulate E2F5 expression level. E2F5 knockdown or overexpress of miR-584-5p gene reversed the circABCB10 who has carcinogenic effects. There was a negative correlation expression between the circABCB10 and miR-584-5p gene, and There was a positive relationship between the expression of circABCB10 and E2F5 in NSCLC tumors. Conclusion: CircABCB10 promoted the progression of NSCLC by modulating the miR-584-5p/E2F5 axis. ABBREVIATION: NSCLC: non-small cell lung cancer; circ RNA: circular RNA; miRNA: micro RNA.

E2f5 is a versatile transcriptional activator required for spermatogenesis and multiciliated cell differentiation in zebrafish.

E2f5 is a member of the E2f family of transcription factors that play essential roles during many cellular processes. E2f5 was initially characterized as a transcriptional repressor in cell proliferation studies through its interaction with the Retinoblastoma (Rb) protein for inhibition of target gene transcription. However, the precise roles of E2f5 during embryonic and post-embryonic development remain incompletely investigated. Here, we report that zebrafish E2f5 plays critical roles during spermatogenesis and multiciliated cell (MCC) differentiation. Zebrafish e2f5 mutants develop exclusively as infertile males. In the mutants, spermatogenesis is arrested at the zygotene stage due to homologous recombination (HR) defects, which finally leads to germ cell apoptosis. Inhibition of cell apoptosis in e2f5;tp53 double mutants rescued ovarian development, although oocytes generated from the double mutants were still abnormal, characterized by aberrant distribution of nucleoli. Using transcriptome analysis, we identified dmc1, which encodes an essential meiotic recombination protein, as the major target gene of E2f5 during spermatogenesis. E2f5 can bind to the promoter of dmc1 to promote HR, and overexpression of dmc1 significantly increased the fertilization rate of e2f5 mutant males. Besides gametogenesis defects, e2f5 mutants failed to develop MCCs in the nose and pronephric ducts during early embryonic stages, but these cells recovered later due to redundancy with E2f4. Moreover, we demonstrate that ion transporting principal cells in the pronephric ducts, which remain intercalated with the MCCs, do not contain motile cilia in wild-type embryos, while they generate single motile cilia in the absence of E2f5 activity. In line with this, we further show that E2f5 activates the Notch pathway gene jagged2b (jag2b) to inhibit the acquisition of MCC fate as well as motile cilia differentiation by the neighboring principal cells. Taken together, our data suggest that E2f5 can function as a versatile transcriptional activator and identify novel roles of the protein in spermatogenesis as well as MCC differentiation during zebrafish development.

miR­132 inhibits high glucose­induced vascular smooth muscle cell proliferation and migration by targeting E2F5.

The dysregulated behavior of vascular smooth muscle cells (VSMCs) serves an important role in the pathogenesis of cardiovascular diseases in diabetes. The present study aimed to investigate the effects of microRNA (miR)­132 on the proliferation and migration of VSMCs under high glucose conditions to mimic diabetes. We observed that the expression of miR­132 was significantly decreased and that of E2F transcription factor 5 (E2F5) was upregulated in high glucose (HG)­treated VSMCs or those obtained from diabetic rats. A dual luciferase reporter gene assay revealed that miR­132 could specifically bind to the 3'­untranslated region of E2F5 and significantly suppress the luciferase activity. The proliferation and migration of diabetic rat or HG­treated VSMCs were increased compared with non­diabetic rat VSMCs and those under normal glucose conditions. Upregulation of miR­132 significantly inhibited the proliferation and migration of diabetic rat VSMCs; similar effects were observed following E2F5 downregulation. The inhibitory effects of miR­132 on the proliferation and migration of HG­treated VSMCs could be reversed by E2F5 overexpression. In conclusion, miR­132 was proposed to inhibit the proliferation and migration of diabetic rat or high­glucose­treated VSMCs by targeting E2F5. The findings of the present study suggested that increasing the expression of miR­132 may serve as a novel therapeutic approach to inhibit the progression of cardiovascular disease in diabetes.

A feed-forward regulatory network lncPCAT1/miR-106a-5p/E2F5 regulates the osteogenic differentiation of periodontal ligament stem cells.

Periodontal ligament stem cells (PDLSCs) are characterized by multiple differentiation potential and potent self-renewal ability, yet much remains to be elucidated that what determines these properties. Long noncoding RNAs (lncRNAs) have been suggested to involve in multiple biological process under physiological and pathological conditions, including osteogenic differentiation. In the present study, we performed comprehensive lncRNA profiling by lncRNA microarray analysis and identified prostate cancer-associated ncRNA transcript-1 (lncPCAT1) was gradually increased in PDLSCs during consecutive osteogenic induction, and it could further positively regulate the osteogenic differentiation both in vitro and in vivo, whereas lncPCAT1 inhibition led to suppressed osteogenic differentiation. Thereafter, we inferred a predicted interaction between lncPCAT1 and miR-106a-5p and then confirmed the direct binding sites of miR-106a-5p on lncPCAT1. Although miR-106a-5p upregulation led to decreased osteogenic differentiation, lncPCAT1 overexpression could reverse its suppression, indicating that lncPCAT1 act as a competing endogenous RNA for miR-106a-5p. Moreover, lncPCAT1 could sponge miR-106a-5p to upregulate miR-106a-5p-targeted gene BMP2, which was a crucial gene involved in osteogenic differentiation. Interestingly, we found that E2F5, another target of miR-106a-5p, could bind to the promoter of lncPCAT1 and then form a feed-forward regulatory network targeting BMP2. In conclusion, our study provided a novel lncRNA-miRNA feed-forward regulatory network and a promising target to modulate the osteogenic differentiation of PDLSCs.

MYCN-induced E2F5 promotes neuroblastoma cell proliferation through regulating cell cycle progression.

The MYCN oncoprotein induces the proliferation of neuroblastoma cells through regulating gene transcription. The E2F transcription factor 5 (E2F5) plays an oncogenic role in several types of cancer, however, its role in neuroblastoma cells remains poorly characterized. We report here that MYCN positively regulates E2F5 expression in neuroblastoma cells. Analyses of chromatin immunoprecipitation (ChIP) and reporter gene assay demonstrate that MYCN directly binds to a Myc E-Box DNA binding motif within the promoter of E2F5 gene, whereby inducing its transcription. In addition, E2F5 knockdown inhibits the proliferation of MYCN-amplified neuroblastoma cells. Furthermore, E2F5 knockdown inhibits cell cycle progression, which could be attributed to its regulation in the expression of related cyclin-dependent kinases (CDKs), including CDK2 and CDK6. These results suggest that MYCN-regulated E2F5 upregulation is an important mechanism through which MYCN induces the proliferation of neuroblastoma cells. In conclusion, this study identifies E2F5 as a pro-proliferative factor in MYCN-amplified neuroblastoma cells, and also implicates it as a potential target in neuroblastoma treatment.

Induction of apoptosis in ovarian cancer cells by miR-493-3p directly targeting AKT2, STK38L, HMGA2, ETS1 and E2F5.

Apoptosis is a form of directed programmed cell death with a tightly regulated signalling cascade for the destruction of single cells. MicroRNAs (miRNAs) play an important role as fine tuners in the regulation of apoptotic processes. MiR-493-3p mimic transfection leads to the induction of apoptosis causing the breakdown of mitochondrial membrane potential and the activation of Caspases resulting in the fragmentation of DNA in several ovarian carcinoma cell lines. Ovarian cancer shows with its pronounced heterogeneity a very high death-to-incidence ratio. A target gene analysis for miR-493-3p was performed for the investigation of underlying molecular mechanisms involved in apoptosis signalling pathways. Elevated miR-493-3p levels downregulated the mRNA and protein expression levels of Serine/Threonine Kinase 38 Like (STK38L), High Mobility Group AT-Hook 2 (HMGA2) and AKT Serine/Threonine Kinase 2 (AKT2) by direct binding as demonstrated by luciferase reporter assays. Notably, the protein expression of RAF1 Proto-Oncogene, Serine/Threonine Kinase (RAF1) was almost completely downregulated by miR-493-3p. This interaction, however, was indirect and regulated by STK38L phosphorylation. In addition, RAF1 transcription was diminished as a result of reduced transcription of ETS proto-oncogene 1 (ETS1), another direct target of miR-493-3p. Taken together, our observations have uncovered the apoptosis inducing potential of miR-493-3p through its regulation of multiple target genes participating in the extrinsic and intrinsic apoptosis pathway.

MicroRNA­34a inhibits esophageal squamous cell carcinoma progression by targeting E2F5.

PURPOSE: Previous studies have explored the role of microRNA-34a (miR-34a) and E2F transcription family in several tumors, however, the expression level and oncogenesis mechanism of these two factors in esophageal squamous cancer cells (ESCC) remains unclear. Our study aims to explore the inhibitory effect of miR-34a in ESCC as well as its downstream factor E2F5. METHODS: We explored the relevant expression level of miR-34a in human tumor tissue as well as in several ESCC cell lines. Through RNA mimic and inhibitor, we examined the specific role of miR-34a in the proliferation, apoptosis and migration of tumor cells, and we further explored the role of downstream factor E2F5 through gain- and loss-of-function analyses. RESULTS: We found that the expression level of miR-34a is significantly downregulated in ESCC tissues as well as in ESCC cell lines, and miR-34a plays an inhibitory role in tumor cell proliferation and migration while it promotes tumor cell apoptosis. We further showed that E2F5 is a direct functional target of miR-34a, as it promotes tumor cell proliferation and migration and inhibits apoptosis. CONCLUSIONS: Our results indicate that the intrinsic expression of miR-34a was relatively low in ESCC. The anti-tumor effect of miR-34a is possibly dependent on the regulation of cell-cycle regulator E2F5.

The putative tumour suppressor miR-1-3p modulates prostate cancer cell aggressiveness by repressing E2F5 and PFTK1.

BACKGROUND: Previous studies report that miR-1-3p, a member of the microRNA-1 family (miR-1), and functions as a tumor suppressor in several different cancers. However, little is known regarding the biological role and intrinsic regulatory mechanisms of miR-1-3p in prostate cancer (PCa). METHODS: In this study, the expression levels of miR-1-3p were first examined in PCa cell lines and tumor tissues by RT-qPCR and bioinformatics. The in vitro and in vivo functional effect of miR-1-3p was examined further. A luciferase reporter assay was conducted to confirm target associations. RESULTS: We found that miR-1-3p was significantly downregulated in advanced PCa tissues and cell lines. Low miR-1-3p levels were strongly associated with aggressive clinicopathological features and poor prognosis in PCa patients. Ectopic expression of miR-1-3p in 22RV1 and LncaP cells was sufficient to prevent tumor cell growth and cell cycle progression in vitro and in vivo. Further mechanistic studies revealed that miR-1-3p could directly target the mRNA 3'- untranslated region (3'- UTR) of two central cell cycle genes, E2F5 and PFTK1, and could suppress their mRNA and protein expression. In addition, knockdown of E2F5 and PFTK1 mimicked the tumor-suppressive effects of miR-1-3p overexpression on PCa progression. Conversely, concomitant knockdown of miR-1-3p and E2F5 and PFTK1 substantially reversed the inhibitory effects of either E2F5 or PFTK1 silencing alone. CONCLUSION: These data highlight an important role for miR-1-3p in the regulation of proliferation and cell cycle in the molecular etiology of PCa and indicate the potential for miR-1-3p in applications furthering PCa prognostics and therapeutics.

MicroRNA-129-3p suppresses tumor growth by targeting E2F5 in glioblastoma.

OBJECTIVE: Neuroma is the most common intracranial tumor. The mechanism of miRNA in glioma has gradually been understood. The purpose of this study was to investigate the role of MicroRNA-129-3p (miR-129-3p) in the pathogenesis of glioblastoma (GBM). PATIENTS AND METHODS: Differential expression of miR-129-3p in samples was analyzed by bioinformatics. PCR was used to detect the expression of miR-129-3p in samples. CCK8 assay was used to detect the cell viability. Transfection of mimic and inhibitor altered the expression of miR-129-3p, and the biological function of miRNA was explored. Luciferase reporter gene was used to detect target genes of miRNA. E2F5 expression was inhibited by transfection of small interfering RNAs. Western blotting was used to detect protein expressions of cells. RESULTS: miR-129-3p was low-expressed in the tissue samples. By transfecting mimic and the inhibitor, we found that increasing the expression of miR-129-3p can inhibit the cell viability. In contrast, inhibition of miR-129-3p promoted cell growth. Luciferase reporter gene and Western blot results suggested that E2F5 can be used as the target gene of miR-129-3p. Knockdown the target gene of the miR-129-3p, E2F5, also inhibited proliferation of glioblastoma. CONCLUSIONS: miR-129-3p can inhibit the growth of glioblastoma by down-regulating the expression of E2F5. miR-129-3p can be a new target for the treatment of glioblastoma. Our research provides new ideas for the target therapy of glioma.