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.

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.

[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.

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.

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.

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.

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.

Controlling centriole numbers: Geminin family members as master regulators of centriole amplification and multiciliogenesis.

To ensure that the genetic material is accurately passed down to daughter cells during mitosis, dividing cells must duplicate their chromosomes and centrosomes once and only once per cell cycle. The same key steps-licensing, duplication, and segregation-control both the chromosome and the centrosome cycle, which must occur in concert to safeguard genome integrity. Aberrations in genome content or centrosome numbers lead to genomic instability and are linked to tumorigenesis. Such aberrations, however, can also be part of the normal life cycle of specific cell types. Multiciliated cells best exemplify the deviation from a normal centrosome cycle. They are post-mitotic cells which massively amplify their centrioles, bypassing the rule for once-per-cell-cycle centriole duplication. Hundreds of centrioles dock to the apical cell surface and generate motile cilia, whose concerted movement ensures fluid flow across epithelia. The early steps that control the generation of multiciliated cells have lately started to be elucidated. Geminin and the vertebrate-specific GemC1 and McIdas are distantly related coiled-coil proteins, initially identified as cell cycle regulators associated with the chromosome cycle. Geminin is required to ensure once-per-cell-cycle genome replication, while McIdas and GemC1 bind to Geminin and are implicated in DNA replication control. Recent findings highlight Geminin family members as early regulators of multiciliogenesis. GemC1 and McIdas specify the multiciliate cell fate by forming complexes with the E2F4/5 transcription factors to switch on a gene expression program leading to centriole amplification and cilia formation. Positive and negative interactions among Geminin family members may link cell cycle control to centriole amplification and multiciliogenesis, acting close to the point of transition from proliferation to differentiation. We review key steps of centrosome duplication and amplification, present the role of Geminin family members in the centrosome and chromosome cycle, and discuss links with disease.

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.

GemC1 controls multiciliogenesis in the airway epithelium.

Multiciliated cells are terminally differentiated, post-mitotic cells that form hundreds of motile cilia on their apical surface. Defects in multiciliated cells lead to disease, including mucociliary clearance disorders that result from ciliated cell disfunction in airways. The pathway controlling multiciliogenesis, however, remains poorly characterized. We showed that GemC1, previously implicated in cell cycle control, is a central regulator of ciliogenesis. GemC1 is specifically expressed in ciliated epithelia. Ectopic expression of GemC1 is sufficient to induce early steps of multiciliogenesis in airway epithelial cells ex vivo, upregulating McIdas and FoxJ1, key transcriptional regulators of multiciliogenesis. GemC1 directly transactivates the McIdas and FoxJ1 upstream regulatory sequences, and its activity is enhanced by E2F5 and inhibited by Geminin. GemC1-knockout mice are born with airway epithelia devoid of multiciliated cells. Our results identify GemC1 as an essential regulator of ciliogenesis in the airway epithelium and a candidate gene for mucociliary disorders.

SNHG16 contributes to breast cancer cell migration by competitively binding miR-98 with E2F5.

Long noncoding RNAs (lncRNAs) have been proved to play important roles in cellular processes of cancer, including the development, proliferation, and migration of cancer cells. In the present study, we demonstrated small nucleolar RNA host gene 16 (SNHG16) as an oncogene on cell migration in breast cancer. Expression levels of SNHG16 were found to be frequently higher in breast cancer tissues than in the paired noncancerous tissues. Gain- and loss-of-function studies proved that SNHG16 significantly promoted breast cancer cell migration. We predicted SNHG16 as a competitive endogenous RNA (ceRNA) of E2F transcription factor 5 protein (E2F5) via competition for the shared miR-98 through bioinformatics analysis, and proved this regulation using relative quantitative real-time PCR (qRT-PCR), western blot, RNA immunoprecipitation (RIP) assay and luciferase reporter assay. In addition, we identified a positive correlation between SNHG16 and E2F5 in breast cancer tissues. Furthermore, we demonstrated that forced expression of miR-98 could partially abrogate SNHG16-mediated increase of breast cancer cells migration, suggesting that SNHG16 promoted cell migration in a miR-98 dependent manner. Taken together, our findings indicated that SNHG16 induces breast cancer cell migration by competitively binding miR-98 with E2F5, and SNHG16 can serve as a potential therapeutic target for breast cancer treatment.

MiR-613 suppresses retinoblastoma cell proliferation, invasion, and tumor formation by targeting E2F5.

Retinoblastoma is a common intraocular malignancy that occurs during childhood. MicroRNAs play critical roles in the regulation of retinoblastoma initiation and progression, and aberrant expression of miR-613 had been reported in various types of cancer. However, the role and mechanism of its function in retinoblastoma are still unclear. In this study, we found that miR-613 was downregulated in retinoblastoma tissues and cell lines. Overexpression of miR-613 suppressed retinoblastoma cell proliferation, migration, and invasion and induced cell cycle arrest in vitro. Additionally, overexpressed miR-613 also inhibited tumor formation of retinoblastoma cells in vivo. We further identified E2F5 as a direct target of miR-613. Reintroduction of E2F5 without 3'-untranslated region reversed the inhibitory effects of miR-613 on cell proliferation and invasion. Our data collectively indicate that miR-613 functions as a tumor suppressor in retinoblastoma through downregulating E2F5, supporting the targeting of the novel miR-613/E2F5 axis as a potentially effective therapeutic approach for retinoblastoma.

Deregulated E2F5/p38/SMAD3 Circuitry Reinforces the Pro-Tumorigenic Switch of TGFß Signaling in Prostate Cancer.

Transforming growth factor-ß signaling exerts divergent effects on normal and cancer cells, although mechanism underlying this differential behavior remains unclear. In this study, expression of 94 genes pertaining to the TGF-ß signaling pathway was compared between tumor and benign tissue samples from the human prostate gland to identify major discriminators driving prostate carcinogenesis. E2F5 was identified as one of the most deregulated genes in prostate cancer tissues, predominantly in samples with Gleason-score 6. Expression of other deregulated components of TGF-ß signaling was examined by qRT-PCR, Western blot, and immune-staining. Function of E2F5 and p38 in prostate cancer was investigated using siRNA-treatment of PC3 cell-line followed by analyses of associated components and cell cycle. Observations revealed that E2F5 overexpression was accompanied by significantly higher phosphorylation of SMAD3 at Ser-208 in the linker region (pSMAD3L) and p38 in tumor tissue. A striking difference in SMAD3 phosphorylation, marked by preponderance of pSMAD3L and pSMAD3C (Ser-423 and 425) in tumor and benign tissues, respectively was noted. Co-localization of E2F5 with pSMAD3L in the nuclei of tumor and PC3 cells indicated a functional interface between the proteins. Downregulation of E2F5 and p38 in PC3 cells resulted in marked reduction of phosphorylation of SMAD3 and perturbation of cell cycle with an arrest of cells in G1 . Our findings unearthed that E2F5/p38 axis played a cardinal role in uncontrolled cellular proliferation in prostate cancer through pSMAD3L activation. It also underscores a strong potential for E2F5 to be incorporated as a tool in early detection of prostate cancer. J. Cell. Physiol. 231: 2482-2492, 2016. © 2016 Wiley Periodicals, Inc.

miR-98 delays skeletal muscle differentiation by down-regulating E2F5.

A genome-wide screen had previously shown that knocking down miR-98 and let-7g, two miRNAs of the let-7 family, leads to a dramatic increase in terminal myogenic differentiation. In the present paper, we report that a transcriptomic analysis of human myoblasts, where miR-98 was knocked down, revealed that approximately 240 genes were sensitive to miR-98 depletion. Among these potential targets of miR-98, we identified the transcriptional repressor E2F5 and showed that it is a direct target of miR-98. Knocking down simultaneously E2F5 and miR-98 almost fully restored normal differentiation, indicating that E2F5 is involved in the regulation of skeletal muscle differentiation. We subsequently show that E2F5 can bind to the promoters of two inhibitors of terminal muscle differentiation, ID1 (inhibitor of DNA binding 1) and HMOX1 (heme oxygenase 1), which decreases their expression in skeletal myoblasts. We conclude that miR-98 regulates muscle differentiation by altering the expression of the transcription factor E2F5 and, in turn, of multiple E2F5 targets.

MicroRNA-34a targets FMNL2 and E2F5 and suppresses the progression of colorectal cancer.

Colorectal cancer (CRC) is one of the most common malignancies. Increasing evidences indicate that dysregulation of miRNAs is a frequent event in CRC and contributes to the pathogenesis of CRC. In this study, we found that over-expression of miR-34a inhibited cell proliferation and invasion, induced a cell cycle arrest and triggered apoptosis, while knockdown of miR-34a showed the opposite effects. Moreover, ectopic miR-34a suppressed tumor growth and metastasis of CRC cells in vivo. FMNL2 and E2F5 were identified as direct targets of miR-34a. Reintroduction of FMNL2 or E2F5 without 3'UTR region reversed the inhibitory effects of miR-34a on cell proliferation and invasion. MiR-34a was down-regulated in CRC cells and inversely correlated with FMNL2 and E2F5 expressions. Our study suggests that miR-34a is an important tumor suppressor of CRC progression by targeting FMNL2 and E2F5, thus providing new insight into the molecular mechanisms underlying CRC progression and establishing a strong potential for the application of miR-34a as a novel therapeutic marker against CRC.

E2F transcription factor 5, a new regulator in adipogenesis to mediate the role of Krüppel-like factor 7 in chicken preadipocyte differentiation and proliferation.

E2F transcription factor 5 (E2F5) gene is a transcription factor, plays an important role in the development of a variety of cells. E2F5 is expressed in human and mouse adipocytes, but its specific function in adipogenesis is unclear. Krüppel-like factor 7 (KLF7) facilitates proliferation and inhibits differentiation in chicken preadipocytes. Our previous KLF7 chromatin immunoprecipitation-sequencing analysis revealed a KLF7-binding peak in the 3' flanking region of the E2F5, indicating a regulatory role of KLF7 in this region. In the present study, we investigated E2F5 potential role, the overexpression and knockdown analyses revealed that E2F5 inhibited the differentiation and promoted the proliferation of chicken preadipocytes. Moreover, we identified enhancer activity in the 3' flanking region (nucleotides +22661/+22900) of E2F5 and found that KLF7 overexpression increased E2F5 expression and luciferase activity in this region. Deleting the putative KLF7-binding site eliminated the promoting effect of KLF7 overexpression on E2F5 expression. Further, E2F5 reversed the KLF7-induced decrease in preadipocyte differentiation and increase in preadipocyte proliferation. Taken together, our findings demonstrate that KLF7 inhibits differentiation and promotes proliferation in preadipocytes by enhancing E2F5 transcription.

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.

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.