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.

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-β activated LINC01980 transcription through the canonical TGF-β/SMAD signaling pathway in HCC. In conclusion, LINC01980, activated by the canonical TGF-β/SMAD pathway, promoted HCC metastasis via miR-376b-5p/E2F5 axis. Therefore, LINC01980 might be a potential prognostic biomarker and therapeutic target of HCC.

[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.

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.

MicroRNA‑34a 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.

E2F5 and LEK1 translocation to the nucleus is an early event demarcating myoblast quiescence

Raf/MEK/ERK signaling in skeletal muscle cells affects several aspects of myogenesis that are correlated with the duration and intensity of the input signal. 23A2RafER(DD) myoblasts directing elevated levels of Raf kinase for 24 h are mitotically inactive. Removal of the stimulus results in cell cycle re-entry and proliferation. Using a proteomic approach, E2F5 and LEK1 were detected in the nuclei of Raf-arrested myoblasts. Disruption of MEK1 activity prevents phosphorylation of ERK1/2 and nuclear translocation of E2F5 and LEK1. The pocket proteins, p107 and p130, remain in the cytoplasm of growth arrested myoblasts irrespective of Raf/ERK activation while pRb translocates to the nucleus. Importantly, both E2F5 and LEK1 are found in the nuclei of non-dividing satellite cells and myonuclei in vivo and in vitro. Our results indicate that Raf-arrested myoblasts may serve as a model system for satellite cell cycle studies and that E2F5 and LEK1 translocation to the nucleus is an important first step during entry into quiescence.

14-3-3 proteins integrate E2F activity with the DNA damage response

The E2F family is composed of at least eight E2F and two DP subunits, which in cells exist as E2F/DP heterodimers that bind to and regulate E2F target genes. While DP-1 is an essential and widespread component of E2F, much less is known about the DP-3 subunit, which exists as a number of distinct protein isoforms that differ in several respects including the presence of a nuclear localisation signal (NLS). We show here that the NLS region of DP-3 harbours a binding site for 14-3-3epsilon, and that binding of 14-3-3epsilon alters the cell cycle and apoptotic properties of E2F. DP-3 responds to DNA damage, and the interaction between DP-3 and 14-3-3epsilon is under DNA damage-responsive control. Further, 14-3-3epsilon is present in the promoter region of certain E2F target genes, and reducing 14-3-3epsilon levels induces apoptosis. These results identify a new level of control on E2F activity and, at a more general level, suggest that 14-3-3 proteins integrate E2F activity with the DNA damage response.

Changes in E2F5 intracellular localization in mouse and human choroid plexus epithelium with development

The choroid plexus epithelium (CPe) is a specialized epithelium involved primarily in the production of cerebrospoinal fluid (CSF) which is important for maintaining an optimal homeostatic environment for the brain. Although, the physiology of the CPe is fairly well understood, its development has not been thoroughly studied. It has been recently shown that mice lacking functional transcription factors, E2F5, foxJ1 or p73, develop non-obstructive hydrocephalus likely due to CPe dysfunction. We have further studied their expression in the mouse and human developing CPe, focusing particularly on E2F5. We show here that in the mouse E2F5, foxJ1 and p73 transcripts are detectable as soon as the choroid plexuses form. E2F5 protein is also detected as soon as the choroid plexuses are morphologically apparent both in mouse and human, suggesting that its expression is regulated at the transcriptional level. E2F5 protein is down-regulated late in embryogenesis and this coincides with a change in its intracellular localization, from predominantly nuclear to cytoplasmic. The pattern of expression and intracellular localization of E2F5 in vivo does not appear to correlate with that of proliferating CPe cells, as indicated by protein cell nuclear antigen (PCNA) staining, but rather with their maturation, as changes in E2F5 localization from the nucleus to the cytoplasm parallel the morphological change from pseudostratified to cuboidal epithelium.