Transcription Factor E2F7 Hampers the Killing Effect of NK Cells against Colorectal Cancer Cells via Activating RAD18 Transcription

As a pivotal defensive line against multitudinous malignant tumors, natural killer (NK) cells exist in the tumor microenvironment (TME). RAD18 E3 Ubiquitin Protein Ligase (RAD18) has been reported to foster the malignant progression of multiple cancers, but its effect on NK function has not been mined. Here, the study was designed to mine the mechanism by which RAD18 regulates the killing effect of NK cells on colorectal cancer (CRC) cells. Expression of E2F Transcription Factor 7 (E2F7) and RAD18 in CRC tissues, their correlation, binding sites, and RAD18 enrichment pathway were analyzed by bioinformatics. Expression of E2F7 and RAD18 in cells was assayed by qRT-PCR and western blot. Dual-luciferase assay and chromatin immunoprecipitation (ChIP) assay verified the regulatory relationship between E2F7 and RAD18. CCK-8 assay was utilized to assay cell viability, colony formation assay to detect cell proliferation, lactate dehydrogenase (LDH) test to assay NK cell cytotoxicity, ELISA to assay levels of granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), and immunofluorescence to detect expression of toxic molecules perforin and granzyme B. High expression of RAD18 and E2F7 was found in CRC tissues and cells. Silencing RAD18 could hamper the proliferation of CRC cells, foster viability and cytotoxicity of NK cells, and increase the secretion of GM-CSF, TNF-α, IFN-γ as well as the expression of perforin and granzyme B. Additionally, ChIP and dual-luciferase reporter assay ascertained the binding relationship between RAD18 promoter region and E2F7. E2F7 could activate the transcription of RAD18, and silencing RAD18 reversed the inhibitory effect of E2F7 overexpression on NK cell killing. This work clarified the inhibitory effect of the E2F7/RAD18 axis on NK cell killing in CRC, and proffered a new direction for immunotherapy of CRC in targeted immune microenvironment.

p53/E2F7 axis promotes temozolomide chemoresistance in glioblastoma multiforme

BACKGROUND

Glioblastoma multiforme (GBM) is the most aggressive form of brain cancer, and chemoresistance poses a significant challenge to the survival and prognosis of GBM. Although numerous regulatory mechanisms that contribute to chemoresistance have been identified, many questions remain unanswered. This study aims to identify the mechanism of temozolomide (TMZ) resistance in GBM.

METHODS

Bioinformatics and antibody-based protein detection were used to examine the expression of E2F7 in gliomas and its correlation with prognosis. Additionally, IC50, cell viability, colony formation, apoptosis, doxorubicin (Dox) uptake, and intracranial transplantation were used to confirm the role of E2F7 in TMZ resistance, using our established TMZ-resistance (TMZ-R) model. Western blot and ChIP experiments provided confirmation of p53-driven regulation of E2F7.

RESULTS

Elevated levels of E2F7 were detected in GBM tissue and were correlated with a poor prognosis for patients. E2F7 was found to be upregulated in TMZ-R tumors, and its high levels were linked to increased chemotherapy resistance by limiting drug uptake and decreasing DNA damage. The expression of E2F7 was also found to be regulated by the activation of p53.

CONCLUSIONS

The high expression of E2F7, regulated by activated p53, confers chemoresistance to GBM cells by inhibiting drug uptake and DNA damage. These findings highlight the significant connection between sustained p53 activation and GBM chemoresistance, offering the potential for new strategies to overcome this resistance.

Transcription factor E2F7 activates PKMYT1 to partially suppress adriamycin sensitivity in gastric cancer through the MAPK signaling pathway

Background

Adriamycin resistance remains an obstacle to gastric cancer chemotherapy treatment. Objective: The objective of this study was to study the role and mechanism of transcription factor E2F7 in sensitivity to ADM chemotherapeutic agents in gastric cancer.

Methods

Cell viability and cell sensitivity were assessed by CCK-8 and IC50 values of ADM were calculated. The impact of ADM on cellular proliferative capacity was assessed through colony formation assay. The binding relationship between E2F7 and PKMYT1 was then verified by dual luciferase assay and chromatin immunoprecipitation assay. ERK1/ERK2 and p-ERK1/p-ERK2 protein expression levels were detected by western blot.

Results

In both gastric cancer tissue and ADM-resistant cells, a conspicuous upregulation of E2F7 and PKMYT1 was observed. Upregulated PKMYT1 was notably enriched in the MAPK signaling pathway. Enhanced levels of E2F7 were shown to not only drive gastric cancer cell proliferation but also engender a reduction in the sensitivity of these cells to ADM. Furthermore, PKMYT1 emerged as a downstream target of E2F7. Activation of E2F7 culminated in the transcriptional upregulation of PKMYT1, and silencing E2F7 reversed the inhibitory impact of PKMYT1 overexpression on ADM sensitivity in gastric cancer cells.

Conclusion

E2F7/PKMYT1 axis might promote the proliferation and partially inhibit ADM sensitivity of gastric cancer cells by activating the MAPK pathway.

E2F7/RAD51AP1 Axis Inhibits Endometrial Cancer Sensitivity to 5-FU via the Fatty Acid Metabolic Pathway

BACKGROUND/AIM

Endometrial cancer (EC) is a frequent gynecological cancer. Studies have demonstrated that the sensitivity of EC toward 5-fluorouracil (5-FU) chemotherapy has decreased, leading to unsatisfactory treatment effects. There is an urgent need to investigate the reasons for the unsatisfactory treatment of EC with 5-FU. The purpose of the study was to investigate the effect of RAD51AP1 after being transcriptionally activated by E2F7 on the sensitivity of EC cells to 5-FU chemotherapy via the fatty acid metabolic pathway.

MATERIALS AND METHODS

mRNA expression data on EC were downloaded from The Cancer Genome Atlas database, subjected to differential expression analysis, and the target genes were determined based on the bioinformatics analysis and literature consulting. The regulatory transcription factor upstream of RAD51AP1 in EC was predicted using the hTFtarget database. The expression of E2F7 and RAD51AP1 was measured by qRT-PCR and western blot. Then, the transcriptional activation relationship between E2F7 and RAD51AP1 was verified by chromatin immunoprecipitation (ChIP) and dual luciferase assays. The IC50 values of EC cells toward 5-FU were determined by the CCK-8 assay, and cell apoptosis was detected by flow cytometry. The expression of apoptosis-related and fatty acid metabolism-related proteins was evaluated by western blot.

RESULTS

Bioinformatics analysis showed that both E2F7 and RAD51AP1 were highly expressed in EC, and the possible binding sites between RAD51AP1 promoter and E2F7 were predicted. ChIP assay and dual luciferase assay confirmed the binding of E2F7 to RAD51AP1 promoter region. Cell experiments showed that overexpressing RAD51AP1 could facilitate the growth and fatty acid metabolism of EC cells, and suppress cell sensitivity to 5-FU, while silencing of E2F7 could reduce the effect of RAD51AP1 overexpression on EC cell growth and sensitivity toward 5-FU.

CONCLUSION

The E2F7/RAD51AP1 axis can promote the growth of EC cells and inhibit cell sensitivity to 5-FU by regulating fatty acid metabolism, suggesting that E2F7/RAD51AP1 axis may be a novel pathway for EC treatment.

CISD2 transcriptional activated by transcription factor E2F7 promotes the malignant progression of cervical cancer

Cervical cancer (CC) is the second most common type of cancer in women, and presents a serious threat to public health. We aimed to investigate the regulatory impacts of CDGSH iron-sulfur domain-containing protein 2 (CISD2) in CC and to discuss its relationship with E2F transcription factor 7 (E2F7). With the employment of real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) and western blot, the expression of CISD2 and E2F7 in SiHa cells before or after transfection was estimated. Cell counting kit-8 (CCK-8) assay, Terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) assay, wound healing and transwell were used to detect the proliferation, apoptosis, migration and invasion of SiHa cells. The activity of CISD2 was detected using luciferase report assay and chromatin immunoprecipitation (ChIP) assay was used to confirm the binding of E2F7 and CISD2 promoter. The contents of proliferation- and apoptosis-related proteins were detected using western blot. Results revealed that CISD2 expression was greatly enhanced in CC cell lines. CISD2 depletion inhibited the proliferation, migration and invasion of SiHa cells but promoted the cell apoptosis. It was also found that E2F7 was remarkably elevated in SiHa cells. According to JASPAR database, the binding sites of E2F7 and CISD2 were predicted and ChIP confirmed the binding of E2F7 and CISD2 promoter. Results obtained from luciferase report assay indicated that E2F7 overexpression increased the activity of CISD2 promoter region. Furthermore, further functional experiments demonstrated that the impacts of E2F7 interference on the proliferation, migration, invasion and apoptosis of SiHa cells were reversed by CISD2 overexpression. In summary, CISD2 silence could alleviate the malignant progression of CC and could be transcribed by E2F7.

Natural compound So-2 suppresses triple-negative breast cancer through inducing ferroptosis via downregulating transcription factor E2F7

Triple-negative breast cancer (TNBC), accounting for about 15∼18% of all breast cancers, is notorious for its poor prognosis, high rate of relapse and short overall survival. Because of lacking effective therapeutic targets or drugs, treatment of TNBC in clinical encounters great obstacle. Siegesbeckiaorientalis L. have been used as a traditional Chinese medicine "Xi-Xian-Cao" for centuries with multiple medicinal benefits including cancerous treatment. We have reported the isolation of twenty-seven germacranolides including So-2 from the aerial parts of S. orientalis with potent cytotoxicity against breast cancer cells. The studyaims to verified the anti-TNBC function of the natural compound So-2 both in vitro and vivo and uncover the underlying mechanism. The results showed that So-2 caused cell cycle arrest and suppress TNBC cell proliferation and migration. Also, So-2 was first identified to be a bona fide ferroptosis inducer in TNBC cells. So-2 effectively suppressed tumor growth of TNBC by using an orthotopic transplantation tumor model. We also characterized the oncogenic role of the transcription factor E2F7 in TNBC. E2F7 was demonstrated to be involved in the ferroptosis-inducing and tumor suppression effect of So-2. Altogether, So-2 exhibits inhibitory effect on TNBC both in vitro and vivo by inducing TNBC ferroptosis via downregulating the expression of E2F7. These findings provide valuable insight into the pathogenesis of TNBC. The natural compound So-2, isolated from Chinese traditional medicine, might be a prospective drug candidate in TNBC therapy.

E2F family play important roles in tumorigenesis

Tumors are serious threats to human health. The transcription factors are regarded as the potential targets for tumor treatment. As an important family of transcription factors, E2F family transcription factors (E2Fs) play vital roles in cell proliferation and regulation. However, the expression feature, gene functions, and molecular interactions of E2Fs in tumorigenesis are not clear. In this study, the transcriptome data, mutation data, and protein-protein interaction data of 10 high-incidence tumors in China from the TCGA database were integrated and analyzed to explore the expression, structure, function, mutation, and phylogenetic characteristics of E2Fs. The results showed that E2F1 and E2F7 were regularly upregulated in the tumor samples. Moreover, E2Fs participated in the regulation of the cell cycle, cell aging, and other signaling pathways. As an important regulator, E2F1 interacted with more proteins than other E2Fs. At the same time, the genetic mutation types of E2Fs varied in tumor type and patient sex, of which gene amplification accounts for the largest proportion. Phylogenetic analysis showed that E2Fs were conserved in 41 species, including fruit flies, nematodes, and humans. Meanwhile, E2Fs had a tendency for gene expansion during evolution. In conclusion, this study clarified the expression pattern, mutation characteristics, and evolutionary trend of E2Fs in high-incidence tumors in China, and suggested that E2F family transcription factors could be novel diagnostic markers for tumor diseases. Furthermore, this work can provide a theoretical basis for the development of anti-tumor-targeted drugs.

Circ_0010235 confers cisplatin resistance in lung cancer by upregulating E2F7 through absorbing miR-379-5p

BACKGROUND

Cisplatin (DDP) treatment is one of the most predominant chemotherapeutic strategies for lung cancer patients. Circular RNAs (circRNAs) have been revealed to participate in the chemoresistance in lung cancer. Hence, the role and mechanism of circ_0010235 in cisplatin resistance in lung cancer was investigated.

METHODS

Expression levels of circ_0010235, microRNA (miR)-379-5p and E2F transcription factor 7 (E2F7) were analyzed using quantitative reverse transcription PCR (qRT-PCR) and western blot. Cell DDP sensitivity, proliferation, apoptosis, invasion, and migration were detected by cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine (EDU) assay, flow cytometry and western blot, respectively. The binding interaction was verified using dual-luciferase reporter assay. A murine xenograft model was established to investigate effects in vivo.

RESULTS

Circ_0010235 was highly expressed in DDP-resistant lung cancer tissues and cells. Knockdown of circ_0010235 elevated DDP sensitivity, constrained proliferation, invasion and migration as well as fostered apoptosis in DDP-resistant lung cancer cells. Moreover, circ_0010235 silencing boosted DDP sensitivity and impeded tumor growth in lung cancer in vivo. Mechanistically, circ_0010235 acted as a sponge for miR-379-5p to elevate the expression of its target E2F7. Rescue experiments showed that miR-379-5p inhibition attenuated circ_0010235 knockdown-evoked reduction on DDP resistance of DDP-resistant cancer cells. In addition, miR-379-5p re-expression elevated DDP sensitivity and suppressed the malignant phenotype of DDP-resistant lung cancer cells through miR-379-5p.

CONCLUSION

Circ_0010235 knockdown reduced DDP resistance and tumor growth via miR-379-5p/ E2F7 axis in lung cancer, suggesting an effective therapeutic target for lung cancer patients.

Abnormal expression pattern of lncRNA H19 participates in multiple myeloma bone disease by unbalancing osteogenesis and osteolysis

BACKGROUND

Accumulating genetic and epigenetic alterations in multiple myeloma (MM) have been demonstrated to be closely associated with osteolytic bone disease, generally characterized as increased osteoclast formation and decreased osteoblast activity. Previously, serum long non-coding RNA (lncRNA) H19 has been proved to be a biomarker for the diagnosis of MM. Whereas, its role in MM-associated bone homeostasis remains largely elusive.

METHODS

A cohort of 42 MM patients and 40 healthy volunteers were enrolled for evaluating differential expressions of H19 and its downstream effectors. The proliferative capacity of MM cells was monitored by CCK-8 assay. Alkaline phosphatase (ALP) staining and activity detection, either with Alizarin red staining (ARS) were employed to assess osteoblast formation. Osteoblast- or osteoclast-associated gene were detected using qRT-PCR and western blot analysis. Bioinformatics analysis, RNA pull-down, RNA immunoprecipitation (RIP), and chromatin immunoprecipitation (ChIP) were subjected to verify H19/miR-532-3p/E2F7/EZH2 axis, which was accounted for epigenetic suppression of PTEN. The functional role of H19 on MM development through unbalancing osteolysis and osteogenesis was also confirmed in the murine MM model.

RESULTS

Upregulation of serum H19 was observed in MM patients, suggesting its positive correlation with the poor prognosis of MM patients. Loss of H19 dramatically weakened cell proliferation of MM cells, promoted osteoblastic differentiation, and impaired osteoclast activity. While reinforced H19 exhibited the opposite effects. Akt/mTOR signaling plays an indispensable role in H19-mediated osteoblast formation and osteoclastgenesis. Mechanistically, H19 served as a sponge for miR-532-3p to upregulate E2F7, a transcriptional activator of EZH2, thereby accounting for modulating epigenetic suppression of PTEN. The in vivo experiments further validated that H19 exerted important impacts on tumor growth through breaking the balance between osteogenesis and osteolysis via Akt/mTOR signaling.

CONCLUSION

Collectively, increased enrichment of H19 in MM cells exhibits an essential role in MM development by disturbing bone homeostasis.

VIRMA Promotes Nasopharyngeal Carcinoma Tumorigenesis and Metastasis by Upregulation of E2F7 in an m6A-Dependent Manner

The N6-methyladenosine (m6A) modification possesses new and essential roles in tumor initiation and progression by regulating mRNA biology. However, the role of aberrant m6A regulation in nasopharyngeal carcinoma (NPC) remains unclear. Here, through comprehensive analyses of NPC cohorts from the GEO database and our internal cohort, we identified that VIRMA, an m6A writer, is significantly upregulated in NPC and plays an essential role in tumorigenesis and metastasis of NPC, both in vitro and in vivo. High VIRMA expression served as a prognostic biomarker and was associated with poor outcomes in patients with NPC. Mechanistically, VIRMA mediated the m6A methylation of E2F7 3'-UTR, then IGF2BP2 bound and maintained the stability of E2F7 mRNA. An integrative high-throughput sequencing approach revealed that E2F7 drives a unique transcriptome distinct from the classical E2F family in NPC, which functioned as an oncogenic transcriptional activator. E2F7 cooperated with CBFB-recruited RUNX1 in a non-canonical manner to transactivate ITGA2, ITGA5, and NTRK1, strengthening Akt signaling-induced tumor-promoting effect.

Harnessing transcriptionally driven chromosomal instability adaptation to target therapy-refractory lethal prostate cancer

Metastatic prostate cancer (PCa) inevitably acquires resistance to standard therapy preceding lethality. Here, we unveil a chromosomal instability (CIN) tolerance mechanism as a therapeutic vulnerability of therapy-refractory lethal PCa. Through genomic and transcriptomic analysis of patient datasets, we find that castration and chemotherapy-resistant tumors display the highest CIN and mitotic kinase levels. Functional genomics screening coupled with quantitative phosphoproteomics identify MASTL kinase as a survival vulnerability specific of chemotherapy-resistant PCa cells. Mechanistically, MASTL upregulation is driven by transcriptional rewiring mechanisms involving the non-canonical transcription factors androgen receptor splice variant 7 and E2F7 in a circuitry that restrains deleterious CIN and prevents cell death selectively in metastatic therapy-resistant PCa cells. Notably, MASTL pharmacological inhibition re-sensitizes tumors to standard therapy and improves survival of pre-clinical models. These results uncover a targetable mechanism promoting high CIN adaptation and survival of lethal PCa.

Hsa-miR-195-5p Inhibits Autophagy and Gemcitabine Resistance of Lung Adenocarcinoma Cells via E2F7/CEP55

Lung adenocarcinoma (LUAD) is a common malignancy. Many studies have shown that LUAD is resistant to gemcitabine chemotherapy, resulting in poor treatment outcomes in patients. We designed this study to reveal influences of hsa-miR-195-5p/E2F7/CEP55 axis on gemcitabine resistance and autophagy of LUAD cells. The expression data of LUAD-related mRNAs were downloaded from TCGA-LUAD database for differential expression analysis. The bioinformatics databases (hTFtarget, starBase and TargetScan) were used to predict the upstream and downstream regulatory molecules of E2F7. Then the binding relationships between E2F7 and regulatory molecules were verified by ChIP and dual-luciferase reporter assay. qRT-PCR and western blot were used to detect the mRNA and protein levels of has-miR-195-5p, E2F7, and CEP55. CCK-8 assay was used to analyze the half-maximal inhibitory concentration (IC₅₀) and cell proliferation ability of LUAD cells after gemcitabine treatment. Apoptosis was detected by flow cytometry. Apoptosis/autophagy markers and LC3 aggregation were detected by western blot and immunofluorescence, respectively. Finally, the mouse transplantation model was constructed to verify the regulation mechanism in vivo. In LUAD cells and tissues, E2F7 and CEP55 were highly expressed, while has-miR-195-5p was relatively less expressed. The ChIP or dual-luciferase assays demonstrated the binding relationships of E2F7 to the CEP55 promoter region and has-miR-195-5p to the 3'-UTR of E2F7. Cell experiments demonstrated that overexpression of hsa-miR-195-5p stimulated LUAD cell apoptosis and inhibited autophagy and gemcitabine resistance, while further overexpression E2F7/CEP55 could reverse the impact by hsa-miR-195-5p overexpression. In vivo experiments identified that hsa-miR-195-5p/E2F7/CEP55 axis constrained the growth of LUAD tumor. Hsa-miR-195-5p promoted apoptosis, repressed proliferation, and autophagy via E2F7/CEP55 and reduced gemcitabine resistance in LUAD, indicating that hsa-miR-195-5p/E2F7/CEP55 may be a novel target for LUAD.

DNA repair/recombination protein 54L promotes the progression of lung adenocarcinoma by activating mTORC1 pathway

Lung adenocarcinoma (LUAD) is the most prevalent form of lung cancer and has a poor prognosis. RAD54L is a DNA repair protein upregulated in several cancer types, but its role in LUAD progression remains unclear. The objective of this study was to characterise the molecular pathways that oncogenic RAD54L modulates to drive LUAD progression. The Cancer Genome Atlas (TCGA)‒LUAD dataset was analysed to compare the RAD54L mRNA expression in LUAD tumours to that in normal lung tissue. RAD54L and E2F7 mRNA expression was confirmed in human cancer cell lines using RT-qPCR. Bioinformatics tools were used to predict the target genes and downstream signalling pathways of RAD54L. Proteins related to RAD54L, apoptosis, migration, and the mTORC1 pathway were assessed by Western blotting. Using the TCGA‒LUAD dataset, we found that RAD54L was higher in LUAD tumours compared to that in non-cancerous lung tissue, and RAD54L levels were significantly correlated with pathological TNM stage and unfavourable prognosis in patients with LUAD. RAD54L was ubiquitously upregulated in LUAD cells (NCI-H1975, H1299, H23 and A549). Furthermore, RAD54L silencing decreased cell proliferation, invasion, and migration, and induced cell apoptosis and G1 cell cycle phase arrest in H1299 and H23 human lung cancer cell lines. E2F7 was predicted as a target gene of RAD54L. E2F7 overexpression restored malignant cell behaviour in si-RAD54L-treated H1299 cells. Bioinformatic analysis suggested that the mTORC1 signalling pathway is downstream of RAD54L. Rapamycin treatment impaired RAD54L-mediated malignant cell behaviour in H1299 cells. Additionally, RAD54L promoted the progression of xenograft tumours and metastasis in vivo. In conclusion, the E2F7-RAD54L axis promotes the progression of LUAD through the mTORC1 signalling pathway.

E2F7 enhances hepatocellular carcinoma growth by preserving the SP1/SOX4/Anillin axis via repressing miRNA-383-5p transcription

E2F family participates in most human malignancies by activating the transcription of the cell cycle-related genes. Whereas, as a specifical atypical member of this family, E2F7 was described as a repressor against its downstream genes and exerted oscillatory and controversial functions in cancers. Our previous study identified a molecular interaction promoting hepatocellular carcinoma (HCC) growth induced by SOX4 and Anillin. Meanwhile, we preliminarily identified SP1 as the upstream activator of SOX4. Intriguingly, we observed that the repressive E2F7 presents a remarkable high expression in HCC, and is positively correlated and involved in the same pathway with the potentially SP1/SOX4/Anillin axis. However, their exact interaction or mechanism controlling tumor progress between these genes has not been illustrated. Thus, we focused on this point in this study and attempted to improve the potential regulating axis in HCC cell proliferation and tumor growth for promoting tumor prevention and control. The expression profile of E2F7 in HCC tissues and tumor cells was detected along with the related candidate genes, through real-time quantitative polymerase chain reaction assay, the Western blot analysis, and the immunohistochemistry assay, combined with bioinformatics analysis of the HCC information from the the Cancer Genome Altas and Gene Expression Omnibus data sets. The correlation between E2F7 and HCC patients' clinicopathologic features was explored. Gain-of and loss-of-function assays were conducted both in vitro and in vivo along with the rescue experiment, for revealing the relative genes' functions in HCC progress. The ChIP and the dual-luciferase reporter assays were performed to verify the transcriptional regulating profile between E2F7 and SP1/SOX4/Anillin axis. E2F7 was upregulated in HCC and significantly correlated with SP1/SOX4/Anillin axis. High E2F7 expression is associated with dismal clinicopathologic features and poor survival of the patients. E2F7 depletion potently impaired SP1/SOX4/Anillin expression and significantly inhibited HCC growth. Furthermore, intensive exploration demonstrated that E2F7 preserves high SP1 levels by abrogating miR-383-5p in a transcriptional way. Atypical E2F7 is an important repressive transcription factor commonly upregulated in the HCC environment. E2F7 facilitates HCC growth by repressing miR-383-5p transcription and sequentially promoting SP1/SOX4/Anillin axis. Our findings provide us with probable targets for HCC prevention and therapeutic treatment.

E2F7 promotes mammalian target of rapamycin inhibitor resistance in hepatocellular carcinoma after liver transplantation

The mammalian target of rapamycin (mTOR) pathway is frequently deregulated and has critical roles in cancer progression. mTOR inhibitor has been widely used in several kinds of cancers and is strongly recommended in patients with hepatocellular carcinoma (HCC) after liver transplantation (LT). However, the poor response to mTOR inhibitors due to resistance remains a challenge. Hypoxia-associated resistance limits the therapeutic efficacy of targeted drugs. The present study established models of HCC clinical samples and cell lines resistance to mTOR inhibitor sirolimus and screened out E2F7 as a candidate gene induced by hypoxia and promoting sirolimus resistance. E2F7 suppressed mTOR complex 1 via directly binding to the promoter of the TSC1 gene and stabilizes hypoxia-inducible factor-1α activating its downstream genes, which are responsible for E2F7-dependent mTOR inhibitor resistance. Clinically, low E2F7 expression could be an effective biomarker for recommending patients with HCC for anti-mTOR-based therapies after LT. Targeting E2F7 synergistically inhibited HCC growth with sirolimus in vivo. E2F7 is a promising target to reverse mTOR inhibition resistance. Collectively, our study points to a role for E2F7 in promoting mTOR inhibitor resistance in HCC and emphasizes its potential clinical significance in patients with HCC after LT.

Comprehensive analysis to identify the RP11-478C19.2/ E2F7 axis as a novel biomarker for treatment decisions in clear cell renal cell carcinoma

•

LncRNA RP11–478C19.2 promotes the progression of ccRCC via the RP11–478C19.2/hsa-miR-181b-5p, hsa-miR-181a-5p, hsa-miR-181c-5p/E2F7 axis.

•

E2F7 could be detected in patients with ccRCC to aid treatment regimen selection, particularly in advanced and metastatic disease.

•

Individuals who overexpress E2F7 may have a greater response to some first-line therapy for ccRCC, including cabozantinib, pazopanib, and sunitinib.

•

Patients with higher expression of E2F7 may have a higher percentage of ICB responses.

Clear cell renal cell carcinoma (ccRCC), accounting for 70–80% of all renal cell carcinomas, is a common malignancy. Survival rates decrease significantly in patients with advanced and metastatic ccRCC. Furthermore, ccRCC is less responsive to radiation and chemotherapy than other cancers. Therefore, targeted therapy and immunotherapy are particularly important for ccRCC management. A growing body of literature recognizes that competitive endogenous RNA (ceRNA) regulatory networks play a crucial role in various cancers. However, the biological functions of the ceRNA network in ccRCC require further investigation. In this study, we built the ceRNA network for ccRCC using the “GDCRNATools” package. After survival analysis, the RP11–478C19.2/hsa-miR-181b-5p, hsa-miR-181a-5p, and hsa-miR-181c-5p/E2F7 axes were obtained for further analysis. Unsupervised clustering was conducted basing on this ceRNA network. The results indicated that the prognosis and immune infiltration levels differed between the two clusters. Furthermore, we conducted correlation analysis, immune infiltration analysis, tumor mutation burden analysis, GSEA analysis, drug sensitivity analysis and pan-cancer analysis of E2F7 to explore its potential role in oncogenesis. Experiments in vitro were performed to confirm the pro-oncogenic impact of E2F7. The results suggest that the RP11–478C19.2/E2F7 axis might be a biomarker for the inclusion of cabozantinib, pazopanib, sunitinib, and immunotherapy in the therapeutic regimen. In summary, we found that the ceRNA-based RP11–478C19.2/E2F7 axis is involved in ccRCC and that it could be a novel biomarker for treatment decisions and a possible therapeutic target to increase the success of targeted therapy and immunotherapy in ccRCC.

microRNA-26a represses pancreatic cancer cell malignant behaviors by targeting E2F7

Dysregulation of microRNAs (miRNAs) exerts key roles in the development of pancreatic cancer (PCa). miR-26a is reportedly a tumor suppressor in cancers. However, whether miR-26a modulates PCa progression is poorly understood. Here, we found that miR-26a was down-regulated in PCa. Overexpressed miR-26a suppressed PCa cell proliferation, colony formation, and tumor stem cell properties. Mechanically, the transcription factor E2F7 is a downstream target of miR-26a. miR-26a decreased E2F7 expression through binding to the 3'-untranslated region (UTR) of E2F7. Decreased miR-26a in PCa tissues was inversely correlated with E2F7. The inhibitory effects of miR-26a in PCa were reversed by E2F7 overexpression. Consistently, the knockout of E2F7 further significantly inhibited the growth of PCa cells combined with miR-26a overexpression. Further study revealed that E2F7 bound the promoter of vascular endothelial growth factor A (VEGFA), a key factor in angiogenesis, and transcriptionally activated the expression of VEGFA. miR-26a overexpression attenuated the effects of E2F7 on VEGFA promotion. Our results uncovered the novel function of miR-26a/E2F7/VEGFA in PCa, making miR-26a a possible target for PCa treatment.

LINC00174 Facilitates Proliferation and Migration of Colorectal Cancer Cells via MiR-3127-5p/ E2F7 Axis

The literature indicates that LINC00174 promotes the growth of colorectal cancer (CRC) cells, but its research needs to be enriched. We tried to explore the function and mechanism of LINC00174 in CRC cell proliferation and migration. Bioinformatics analysis predicted the binding relationship and expressions of lncRNA, miRNA and mRNA. Clinical study analyzes the relationship between LINC00174 and clinical data characteristics of CRC patients. The expressions of LINC00174, miR-3127-5p and E2F7 were verified by RT-qPCR, and the combination of the two was verified by dual luciferase analysis and RNA immunoprecipitation as needed. Western blot was used to detect the expression of EMT-related protein and E2F7 protein. Functional experiments were used to evaluate the function of the target gene on CRC cells. LINC00174 was up-regulated in CRC clinical samples and cells and was related to the clinical characteristics of CRC patients. High-expression of LINC00174, contrary to the effect of siLINC00174, promoted cell viability, proliferation, migration and invasion, up-regulated the expressions of N-Cadherin, Vimentin, E2F7, and inhibited the expression of E-Cadherin. MiR-3127-5p was one of the targeted miRNAs of LINC00174 and was down-regulated in CRC samples. In addition, miR-3127-5p mimic partially reversed the malignant phenotype of CRC cells induced by LINC00174. Besides, E2F7 was a target gene of miR-3127-5p, and LINC00174 repressed miR-3127-5p to regulate E2F7. Our research reveals that LINC00174 affected the biological characteristics of CRC cells through regulated miR-3127-5p/ E2F7 axis.

LncRNA SNHG19 Promotes the Development of Non-Small Cell Lung Cancer via Mediating miR-137/E2F7 Axis

Objective

Non-small cell lung cancer (NSCLC) is a common malignant tumor, which has high incidence and low the 5-year survival rate. Long non-coding RNAs (lncRNAs) play critical roles in carcinoma occurrence and metastasis. Herein, our aim was to investigate the effects of lncRNA SNHG19 in NSCLC progression.

Materials and Methods

Long non-coding RNA Small Nucleolar RNA Host Gene 19 (lncRNA SNHG19) expression level was measured by bioinformatics and qRT-PCR. Edu, Transwell, and scratch assays were performed to explore the role of si-SNHG19 or SNHG19 on NSCLC progression. Luciferase assay was used to verify the relationship between SNHG19/E2F7 and miR-137. The experiment of Xenograft was used for exploring the function of SNHG19 in vivo.

Results

SNHG19 was upregulated in cancer tissues, patients plasma and cell lines of NSCLC. Knockdown of SNHG19 inhibited cell proliferation, migration, and invasion. Luciferase assay confirmed that SNHG19 regulated E2F7 expression via interacting with miR-137. Overexpression of SNHG19 accelerated NSCLC tumor progression via miR-137/E2F7 axis both in vitro and in vivo.

Conclusions

Our results clarified the SNHG19 function for the first time, and SNHG19 promoted the progression of NSCLC, which was mediated by the miR-137/E2F7 axis. This study might provide new understanding and targets for NSCLC diagnosis and treatment.

E2F7 Transcriptionally Inhibits MicroRNA-199b Expression to Promote USP47, Thereby Enhancing Colon Cancer Tumor Stem Cell Activity and Promoting the Occurrence of Colon Cancer

microRNAs (miRNAs) can modulate the expression level of genes in a post-transcription manner, which are closely related to growth and metastasis of colon cancer. Herein, we aimed to explore how miR-199b influences colon cancer and to characterize its underlying molecular mechanism associating with E2F transcription factor 7 (E2F7). Assays of RT-qPCR, Western blot, and immunohistochemistry were utilized to detect the expression of E2F7 in the tissue samples collected from 30 patients diagnosed with colon cancer. Flow analysis was utilized to detect the ratio of ALDH1⁺ and CD133⁺ colon cancer stem cells. The interaction between E2F7, miR-199b, USP47, and MAPK was identified by ChIP-Seq analysis, luciferase reporter, RNA pull-down, co-immunoprecipitation, as well as glutathione-S-transferase (GST) pull-down experiments. Based on the gain- and loss-of-function approaches, the cellular functions of colon cancer cells by the E2F7-regulated miR-199b/USP47/MAPK axis were assessed. It was identified that E2F7 are expressed highly in the collected colon cancer tissues. E2F7 silencing reduced the production of ALDH1⁺ and CD133⁺ colon cancer stem cells and antagonized the effects of 5-fluorouracil (5-FU) treatment. Besides, the silencing of E2F7 was observed to suppress the oxidative stress, proliferation, migration, as well as invasion of ALDH1⁺ cells in vitro and tumorigenesis of colon cancer cells in vivo. Our findings reveal the pro-oncogenic effect of E2F7 on colon cancer development, highlighting E2F7 as a novel target for therapeutic strategy for colon cancer.

Circ-AASDH functions as the progression of early stage lung adenocarcinoma by targeting miR-140-3p to activate E2F7 expression

Background

Lung adenocarcinoma (LUAD), which is the most common subtype of non-small cell lung cancer, is a leading course of cancer-related mortality worldwide. Recently, circular RNA (CircRNAs) has become a hot spot in cancer research because of its important role in tumorigenesis and development and its superior stability. This study aims to clarify the role of circ-AASDH in LUAD and explore its competitive endogenous RNA mechanism.

Methods

The circ-AASDH, miR-140-3p and E2F transcription factor 7 (E2F7) mRNA expression levels were detected via qRT-PCR. CCK-8 and colony formation assay were used to evaluate the ability of cell proliferation. Transwell assay and wound healing assay were performed to measure the invasion and migration ability. Flow cytometry was used to detect the apoptosis of cells. Moreover, Sanger sequencing, RNaseR treatment and divergent primers were used to verify the circular structure. Luciferase reporter and RNA pull-down experiment were performed to characterize the ceRNA mechanism of circ-AASDH. The xenograft model of mice was established to investigate the tumorigenicity of circ-AASDH to LUAD in vivo.

Results

By screening for differentially expressed circRNAs, we found that circ-AASDH was highly expressed in LUAD tissues and cells and correlated with tumor size, clinical stage and poor prognosis. Transfection of si-circ-AASDH can inhibit the proliferation and migration of LUAD cells and promote apoptosis in vitro. In mechanism, circ-AASDH could be used as a sponge of miR-140-3p to weaken its inhibition on the expression of E2F7. Additionally, the overexpression of circ-AASDH could deduce the suppression of miR-140-3p on the malignant progression of LUAD cells. Besides, silencing of circ-AASDH inhibited cell proliferation and migration by regulating the expression of E2F7. Furthermore, overexpression of circ-AASDH can promote the growth of LUAD in vivo.

Conclusions

Circ-AASDH/miR-140-3p/E2F7 regulating axis promoted the progression in LUAD. Our results provided ideas for understanding the biological mechanism of circ-AASDH and clarify potential therapeutic targets in LUAD.

Circ-CCS is identified as a cancer-promoting circRNA in lung cancer partly by regulating the miR-383/E2F7 axis

BACKGROUND

Increasing biomolecules have been found to be involved in the lung cancer development. This study will perform the function and mechanism analyses of a novel circular RNA copper chaperone for superoxide dismutase (circ-CCS) in lung cancer.

METHODS

Circ-CCS, microRNA-383 (miR-383) and E2F transcription factor 7 (E2F7) were quantified by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability was detected using Cell Counting Kit-8 (CCK-8). Clonal ability was measured by colony formation assay. Cell apoptosis was determined via flow cytometry. Cell migration and invasion were assessed by transwell assay. Detection of protein was completed using western blot. Xenograft assay was used for the functional analysis of circ-CCS in vivo. The binding between targets was proved by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. E2F7 protein level was also examined by Immunohistochemistry (IHC) analysis in human tissues.

RESULTS

Circ-CCS was upregulated in lung cancer and could predict poor prognosis. Downregulation of circ-CCS inhibited lung cancer cell growth and metastasis while promoted apoptosis in vitro, and suppressed tumorigenesis of lung cancer in vivo. Circ-CCS had sponge effect on miR-383 and the function of si-circ-CCS was achieved by upregulating miR-383. E2F7 was a target gene of miR-383 and its downregulation was responsible for the anti-cancerous role of miR-383 in lung cancer. Circ-CCS could elevate E2F7 expression via interacting with miR-383.

CONCLUSION

Circ-CCS was shown to facilitate lung cancer progression via the miR-383/E2F7 axis, exhibiting the pivotal value of circ-CCS in diagnosis and treatment of lung cancer.

Circ_SATB2 Attenuates the Anti-Tumor Role of Celastrol in Non-Small-Cell Lung Carcinoma Through Targeting miR-33a-5p/E2F7 Axis

Background

Celastrol (Cela) was a natural compound that exerted anti-tumor activity in many cancer cells. Nevertheless, the molecular mechanism behind the anti-tumor role of Cela in non-small-cell lung carcinoma (NSCLC) remains to be clarified.

Methods

Flow cytometry was used to analyze cell cycle progression and apoptosis. Colony formation assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay were used to analyze cell proliferation. Cell migration and invasion abilities were assessed by transwell assays. Quantitative real-time polymerase chain reaction (qRT-PCR) was implemented for the detection of RNA levels. Western blot assay was used for the determination of protein levels. Dual-luciferase reporter assay was conducted to confirm the interaction between microRNA-33a-5p (miR-33a-5p) and circular RNA SATB homeobox 2 (circ_SATB2) or E2F transcription factor 7 (E2F7). Xenograft tumor assay was conducted to test the roles of Cela and circ_SATB2 in NSCLC progression in vivo.

Results

Cela hampered the malignant behaviors of NSCLC cells. Cela down-regulated circ_SATB2 level in NSCLC cells. Cela stimulation-induced suppressive influence in NSCLC progression was alleviated by circ_SATB2 accumulation. E2F7 interference overturned circ_SATB2-mediated effects in Cela-stimulated NSCLC cells. MiR-33a-5p was a target of circ_SATB2, and E2F7 was verified as a target of miR-33a-5p. Circ_SATB2 attenuated Cela-mediated effects through targeting miR-33a-5p in NSCLC cells. Cela-mediated suppressive effect on tumor growth was partly attenuated by the overexpression of circ_SATB2 in vivo.

Conclusion

Cela suppressed NSCLC development through regulating circ_SATB2/miR-33a-5p/E2F7 signaling cascade.

Up-Regulation of miR-26a-5p Inhibits E2F7 to Regulate the Progression of Renal Carcinoma Cells

Background

Metastasis is the main cause of renal cell carcinoma (RCC) tumor death, and effective inhibition of RCC metastasis is an essential means to meliorate the prognosis of RCC patients. MicroRNAs (miRs) have been proved to be stable and important biomarkers for several malignancies. This study is therefore set out to explore the metastasis-related miR and its mechanism in RCC.

Methods

The expression of miR- 26a -5p in RCC was analyzed using the expression profile in the Cancer Genome Atlas (TCGA). MiR-26a-5p and E2F transcription factor 7 (E2F7) in RCC patients were detected by qRT-PCR. Cell Counting Kit-8 (CCK-8) was adopted to assess cell proliferation, Transwell was utilized to evaluate migration and invasion, and flow cytometry (FC) was used to determine apoptosis. Mouse cell-derived and patient-derived xenotransplantation models were established to evaluate the effect of miR-26a-5p on tumor growth and metastasis in vivo. The molecular mechanism of miR-26a-5p was analyzed by dual-luciferase reporter (DLR) gene analysis, qRT-PCR, and Western blot (WB) both in vivo and in vitro.

Results

MiR-26a-5p was reduced in renal carcinoma cells and may serve as a biomarker for renal cancer metastasis and prognosis. MiR-26a-5p up-regulation inhibited migration and invasion in renal cell lines and tumor metastasis in vivo. Bioinformatics target prediction and RNA-seq results showed that E2F7 was among the targets of miR-26a-5p and was significantly inhibited by miR-26a-5p in vivo and in vitro.

Conclusion

MiR-26a-5p presents low expression in RCC and promotes RCC cell apoptosis and prevents cells from proliferating and invading by targeting E2F7, which is a promising therapeutic target for RCC.

LncRNA MYLK-AS1 facilitates tumor progression and angiogenesis by targeting miR-424-5p/E2F7 axis and activating VEGFR-2 signaling pathway in hepatocellular carcinoma

BACKGROUND

Long non-coding RNAs (lncRNAs) are crucial in the invasion, angiogenesis, progression, and metastasis of hepatocellular carcinoma (HCC). The lncRNA MYLK-AS1 promotes the growth and invasion of HCC through the EGFR/HER2-ERK1/2 signaling pathway. However, the clinical significance of MYLK-AS1 in HCC still needs to be further determined.

METHODS

Bioinformatic analysis was performed to determine the potential relationship among MYLK-AS1, miRNAs and mRNAs. A total of 156 samples of normal liver and paired HCC tissues from HCC patients were used to evaluate MYLK-AS1 expression by qRT-PCR. Human HCC cell lines were used to evaluate the colony formation, cell proliferation, migration, invasion, cell cycle and apoptosis after transfection of lentiviral short-hairpin RNAs (shRNAs) targeting MYLK-AS1 or MYLK-AS1 vectors. The competitive endogenous RNA (ceRNA) mechanism was clarified using fluorescence in situ hybridization (FISH), Western blotting, qPCR, RNA binding protein immunoprecipitation (RIP), and dual luciferase reporter analysis.

RESULTS

MYLK-AS1 up-regulation was detected in the HCC tumor tissues and cell lines associated with the enhancement of the angiogenesis and tumor progression. The down-regulation of MYLK-AS1 reversed the effects on angiogenesis, proliferation, invasion and metastasis in the HCC cells and in vivo. MYLK-AS1 acted as ceRNA, capable of regulating the angiogenesis in HCC, while the microRNA miR-424-5p was the direct target of MYLK-AS1. Promoting the angiogenesis and the tumor proliferation, the complex MYLK-AS1/miR-424-5p activated the VEGFR-2 signaling through E2F7, whereas the specific targeting of E2F transcription factor 7 (E2F7) by miR-424-5p, was indicated by the mechanism studies.

CONCLUSIONS

MYLK-AS1 and E2F7 are closely related to some malignant clinicopathological features and prognosis of HCC, thus the MYLK-AS1/ miR-424-5p/E2F7 signaling pathway might represent a promising treatment strategy to combat HCC.

MiR-10b inhibits migration and invasion of pancreatic ductal adenocarcinoma via regulating E2F7

BACKGROUND

Abnormal microRNAs (miRNAs) expression is closely related to the development and poor prognosis of pancreatic ductal adenocarcinoma (PDAC). We aimed to elucidate the invasive mechanism and clinical significance of miR-10b in PDAC.

METHODS

The RNA sequence data of pancreatic cancer were extracted from the TCGA database. R packages were performed to analyze the differential expression of RNAs. TargetScan, picTar, and miRanda were used to predict the target gene of miRNA. The expression level of the selected candidate was tested by western blot and RT-PCR in PDAC cells and tissues. Scrape and Transwell assays were determined the effect of candidate molecules on cell migration and invasion. The gain of function and loss of function was achieved by co-culture with mimics and vector. Luciferase reporters were generated based on the psiCHECK2 vector. The relative luciferase activity was measured with the Dual-Luciferase Reporter Assay System and Infinate M200 PRO microplate reader.

RESULTS

Based on the TCGA data and bioinformatics analysis, we obtained seven differentially expressed miRNAs. Both TCGA data and our center clinical date indicated that miR-10b was contributed to the poor survival of PDAC. Based on the target gene prediction database, we found that E2F7 was a target mRNA of miR-10b. In subsequent experiments in molecular biology, miR-10b expression was downregulated in PDAC cells and tissues, while E2F7 was upregulated. Scrape and Transwell assay indicated that miR-10b could inhibit the invasion and migration of PDAC. MiR-10b was confirmed to be by the E2F7 targeting site by dual-luciferase report. Moreover, rescue experiments prove that miR-10b could inhibit the invasion and migration of PDAC cells by regulating E2F7 expression.

CONCLUSION

Our results suggest that miR-10b could inhibit the progression of PDAC by regulating E2F7 expression and acts as an independent prognostic risk factor for PDAC.

Five Genes Associated With Survival in Patients With Lower-grade Gliomas Were Identified by Information-theoretical Analysis

BACKGROUND/AIM

Understanding of the molecular events associated with progression and survival differences in patients with lower-grade gliomas (LGGs) is still unclear. The comparison of findings across studies using different datasets and methods is essential for a new molecular-based classification system. The aim of the study was to identify biomarkers for prognostic classification of patients with LGGs, and furthermore to lay a foundation for future development of targeted therapies for LGGs.

PATIENTS AND METHODS

Using information-theoretic and statistical approaches, we analyzed mRNA expression data for 18,413 genes from LGG samples in order to identify candidate biomarkers for survival. The candidate genes were then evaluated for their potential as prognostic biomarkers using multivariable Cox regression analyses that adjusted for the effects of age and grade.

RESULTS

WEE1, EMP3, E2F7, CD58 and NSUN7 genes were identified as candidate biomarkers of LGGs and their high expression was associated with significantly shorter survival. The hazard ratios for mortality were 5.02 (95% CI=3.40-7.40) for WEE1, 5.45 (95% CI=3.63-8.18) for EMP3, 4.49 (95% CI=3.03-6.66) for E2F7, 4.77 (95% CI=3.22-7.06) for CD58 and 4.38 (95% CI=2.97-6.47) for NSUN7. In addition, the expression pattern of these genes, associated with shorter survival in LGGs, was also observed in glioblastoma multiforme.

CONCLUSION

Identification of genes associated with poor outcomes will provide insights into novel biological mechanisms that may lead to improvement in progression and survival for patients with LGGs.

SNHG7 Contributes to the Progression of Non-Small-Cell Lung Cancer via the SNHG7/miR-181a-5p/E2F7 Axis

Background

Non-small-cell lung cancer (NSCLC) is a common malignant tumor with very high mortality. Small nucleolar RNA host gene 7 (SNHG7) was associated with many tumors progression. We aimed to explore the role and regulatory mechanism of SNHG7 in the development of NSCLC.

Methods

The expression of SNHG7, miR-181a-5p and E2F transcription factor 7 (E2F7) was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression of E2F7 was evaluated by Western blot. Cell Counting Kit-8 (CCK-8) assay was conducted to explore cell proliferation. Flow cytometry was used to examine cell apoptosis. The clonogenic examination was performed to reflect cell population dependence and proliferative ability. Transwell assay was used to assess cell migration and invasion. The potential target relationship between miR-181a-5p and SNHG7 or E2F7 was analyzed by dual-luciferase reporter assay. A xenograft mouse model was generated to verify the effect of SNHG7 on tumor growth in vivo.

Results

SNHG7 and E2F7 were increased, while miR-181a-5p was decreased in NSCLC. Knockdown of SNHG7 suppressed cell viability, clonogenic, migration, invasion and tumor growth, and promoted cell apoptosis. SNHG7 acted as a sponge of miR-181a-5p and E2F7 was directly interacted with miR-181a-5p. Overexpression of miR-181a-5p had the same functional effect as SNHG7 knockdown on the progression of NSCLC cells. E2F7 was negatively correlated with miR-181a-5p and positively correlated with SNHG7. Moreover, miR-181a-5p inhibition or E2F7 overexpression abolished the effect of SNHG7 knockdown on the progression of NSCLC cells.

Conclusion

SNHG7 regulated the development of NSCLC cells by the miR-181a-5p/E2F7 axis.

Expression and prognostic role of E2F transcription factors in high-grade glioma

Introduction

Patients with high‐grade glioma (HGG) suffered poor survival due to inherent or acquired therapeutic resistance and refractory recurrence. The outcome of HGG patients has improved little during the past decade. Therefore, molecular signatures are urgently needed for improving diagnosis, survival prediction and identification of therapeutic targets for HGG. E2F transcription factors (E2Fs), a family of transcription factors recognized as master regulators of cell proliferation, have been found to be involved in the pathogenesis of various tumor types.

Aims

To investigate the expression of E2Fs and their prognosis value in high‐grade glioma (HGG).

Results

Expression of E2Fs was analyzed in 394 HGG samples from TCGA dataset. E2Fs were generally expressed in HGG. Except for E2F3 and E2F5, expression of E2Fs was significantly upregulated and linked with grade progression. E2F1, E2F2, E2F7, and E2F8 were highly correlated with aggressive proliferation oncogenes, as well as potential therapeutic resistance oncogenes. Elevated E2Fs (not E2F3) were associated with adverse tumor features and poorer outcome. E2F7 and E2F8 exhibited superior outcome prediction performance compared with other E2Fs. Additionally, E2F7 and E2F8 independently predicted poorer survival in HGG patients. Gene set enrichment analysis identified a variety of critical oncogenic pathways that were tightly associated with E2F7 or E2F8, including epithelial‐mesenchymal transition, NFκB, STAT3, angiogenesis pathways. Furthermore, elevated expression of E2F7 indicated worse therapeutic response of HGG to irradiation and silencing of E2F7 conferred higher cell‐killing effect when combined with irradiation treatment. Mechanically, E2F7 directly regulates the transcriptional activity of EZH2 via binding at the corresponding promoter area.

Conclusions

E2Fs (except for E2F3 and E2F5) are highly expressed in HGG and indicate adverse outcome. E2F7 and E2F8 were identified as novel potential prognostic markers in HGG. E2F7 was further validated to be closely associated with radioresistance of HGG and a critical transcriptional regulator of EZH2.

miR-129-5p inhibits proliferation, migration, and invasion in rectal adenocarcinoma cells through targeting E2F7

microRNAs (miRNAs), a kind of small noncoding RNAs, are considered able to regulate expression of genes and mediate RNA silencing. miR-129-5p was shown to be a cancer-related miRNA. However, the influence of miR-129-5p in rectal adenocarcinoma (READ) development remains to be determined. Based on the TCGA data, downregulation of miR-129-5p in READ samples was observed. Manual restoration of the miR-129-5p in SW1463 and SW480 cell lines significantly inhibited invasion, migration, and proliferation of READ cell lines, while the apoptosis ability was enhanced. Meanwhile, we found E2F7 acted as a potential target of miR-129-5p and was upregulated in READ samples. E2F7 upregulation reversed the repression of miR-129-5p on READ development. Finally, in vivo experiments showed that inhibition of tumor growth in nude mice was achieved through upregulating miR-129-5p. Overall, our findings suggest increasing of miR-129-5p leads to the suppression of READ progression through regulating the expression of E2F7, which may provide novel insights into the treatment of READ.

microRNA-935 is reduced in non-small cell lung cancer tissue, is linked to poor outcome, and acts on signal transduction mediator E2F7 and the AKT pathway

BACKGROUND

A potential role for microRNA-935 (miR-935) has been identified in several cancers but not in non-small cell lung cancer (NSCLC). We hypothesised changes in miR-935 in NSCLC, and proposed mechanisms that may further explain its role in carcinogenesis.

METHODS

NSCLC tissue and nearby normal tissue was obtained from 101 patients and was probed by qRT-PCR for miR-935 expression. The role of miR-935 and a potential target (signal transduction factor E2F7) was determined in cell lines by a dual luciferase assay. The function of miR-935 was investigated through metabolic activity (MTT) and transwell migration assays. Western blot and immunocytochemical assays examined protein expression level. Growth of miR-935 transfected or untransfected cells was measured via xenograft tumour formation.

RESULTS

miR-935 was reduced in cancer tissue and was related to lymph node metastases, tumour node metastasis status and poor prognosis (all p < 0.02). In vitro, miR-935 suppressed cell proliferation, migration and invasion in NSCLC cells through targeting E2F7. Furthermore, E2F7 was upregulated in NSCLC tissue associated with poor prognosis (p = 0.0203) of NSCLC patients. miR-935 suppressed the epithelial-mesenchymal transition and AKT pathways in NSCLC and inhibited the tumour growth in vivo.

CONCLUSION

Altered miR-935 in lung cancer biopsy tissue may be a diagnostic tool and could direct treatment. Involvement in carcinogenesis is implied by its suppression of the development of NSCLC via targeting E2F7 and inhibiting AKT pathway.

MicroRNA-302a/d inhibits the self-renewal capability and cell cycle entry of liver cancer stem cells by targeting the E2F7/AKT axis

BACKGROUND

There is increasing evidence that liver cancer stem cells (LCSCs) contribute to hepatocellular carcinoma (HCC) initiation and progression. MicroRNA (miRNA) plays a significant functional role by directly regulating respective targets in LCSCs-triggered HCC, however, little is known about the function of the miRNA-302 family in LCSCs.

METHODS

MiRNAs microarray was used to detect the miRNAs involved in LCSCs maintenance and differentiation. Biological roles and the molecular mechanism of miRNA-302a/d and its target gene E2F7 were detected in HCC in vitro. The expression and correlation of miRNA-302a/d and E2F7 in HCC patients was evaluated by quantitative PCR and Kaplan-Meier survival analysis.

RESULTS

We found that the miRNA-302 family was downregulated during the spheroid formation of HCC cells and patients with lower miRNA-302a/d expression had shorter overall survival (OS) and progression-free survival (PFS). Moreover, E2F7 was confirmed to be directly targeted and inhibited by miRNA-302a/d. Furthermore, concomitant low expression of miRNA-302a/d and high expression of E2F7 correlated with a shorter median OS and PFS in HCC patients. Cellular functional analysis demonstrated that miRNA-302a/d negatively regulates self-renewal capability and cell cycle entry of liver cancer stem cells via suppression of its target gene E2F7 and its downstream AKT/β-catenin/CCND1 signaling pathway.

CONCLUSIONS

Our data provide the first evidence that E2F7 is a direct target of miRNA-302a/d and miRNA-302a/d inhibits the stemness of LCSCs and proliferation of HCC cells by targeting the E2F7/AKT/β-catenin/CCND1 signaling pathway.

SNHG6 functions as a competing endogenous RNA to regulate E2F7 expression by sponging miR-26a-5p in lung adenocarcinoma

Increasing evidence has highlighted the pivotal roles of deregulated long non-coding RNAs (lncRNAs) in tumourigenesis. However, the biological functions and mechanisms of lncRNAs in human lung adenocarcinoma (LUAD) remain elusive. Small nucleolar RNA host gene 6 (SNHG6), a novel lncRNA, is aberrantly expressed in various cancers. In this study, SNHG6 was upregulated in LUAD tissues, and its upregulation was positively associated with advanced TNM stage, large tumour size and poor overall survival (OS) in LUAD patients. Gain- and loss-of-function experiments confirmed that SNHG6 promoted cell cycle progression, cell proliferation, migration and invasion, and epithelial-mesenchymal transition (EMT) in vitro. Animal experiments demonstrated that SNHG6 knockdown remarkably inhibited xenograft formation in vivo. Moreover, mechanistic experiments identified that SNHG6 functions as a competing endogenous RNA (ceRNA) through competitively sponging miR-26a-5p to regulate E2F7 expression, cell motility and EMT in LUAD cells. In summary, our findings reveal that SNHG6 may act as an oncogenic lncRNA in LUAD carcinogenesis by regulating the miR-26a-5p/E2F7 axis.

The protective role of all-transretinoic acid (ATRA) against colorectal cancer development is achieved via increasing miR-3666 expression and decreasing E2F7 expression

OBJECTIVE

Colorectal cancer (CRC) is one of the most common malignancies with high morbidity and mortality rates worldwide. This study aimed to investigate whether miR-3666 was involved in inhibitory effects of all-transretinoic acid (ATRA) on the development of colorectal cancer (CRC).

MATERIAL AND METHODS

Surgical specimens of CRC tissues and adjacent non-tumor mucosa were collected for determining miR-3666 expression. Human CRC HCT116 cells were treated with different doses of ATRA (10, 20, 40, and 60 μM, respectively) and/or transfected with miR-3666 mimic, miR-3666 inhibitor, E2F7 siRNAs or their controls, respectively. After different treatments, cell viability, apoptosis, migration and invasion were detected. The regulatory relationship between miR-3666 and E2F7 was investigated. Furthermore, the association between MAPK/ERK pathway and ATRA or miR-3666/E2F7 was explored.

RESULTS

The miR-3666 was lowly expressed in CRC tissues, while E2F7 was highly expressed. ATRA decreased HCT116 cell viability, migration, and invasion, and induced apoptosis, indicating that ATRA inhibited the malignant behaviors of HCT116 cells. Moreover, ATRA increased miR-3666 expression, and effects of ATRA on the malignant behaviors of HCT116 cells were achieved by positive regulating miR-3666 expression. Furthermore, E2F7 was a target gene of miR-3666, and knockdown of E2F7 reversed the combined effects of ATRA and miR-3666 inhibitor on the malignant behaviors of HCT116 cells. Besides, ATRA inhibited the activation of MAPK/ERK signaling pathway, which was reversed by inhibition of miR-3666.

CONCLUSIONS

Our results reveal that ATRA protects against CRC development possible via increasing miR-3666 expression and decreasing E2F7 expression. MiR-3666/E2F7 may play a key role in regulating the inhibitory effects of ATRA on HCT116 cells via suppressing the activation of MAPK/ERK signaling pathway.

MiR-129 triggers autophagic flux by regulating a novel Notch-1/ E2F7/Beclin-1 axis to impair the viability of human malignant glioma cells

Abnormalities of autophagy have been implicated in an increasing number of human cancers, including glioma. To date, there is a wealth of evidence indicating that microRNAs (miRNAs) contribute significantly to autophagy in a variety of cancers. Previous studies have suggested that miR-129 functioned as an important inhibitor of the cell cycle and could promote the apoptosis of many cancer cell lines in vitro. Here, we reported that miR-129 acted as a potent inducer of autophagy. Forced expression of miR-129 could induce autophagic flux by targetedly suppressing Notch-1 in glioma cells. The autophagy induced by miR-129 could restrain the activity of mammalian target of rapamycin (mTOR) and upregulate Beclin-1. Moreover, we demonstrated that E2F transcription factor 7 (E2F7) could also trigger autophagic flux by upregulating Beclin-1 and mediating miR-129-induced autophagy. Additionally, knockdown of Notch-1 could upregulate the expression of E2F7, whereas downregulation of E2F7 alleviated shNotch-1-induced autophagic flux. In particular, knockdown of endogenous Beclin-1 could effectively reduce autophagic flux stimulated by miR-129 and E2F7. Interestingly, upon attenuation of miR-129- or E2F7-triggered autophagic flux rescued cell viability suppressed by them. More importantly, intratumoral injection of pHAGE-miR-129 lentivirus in a nude mouse xenograft model significantly restrained tumor growth and triggered autophagy. In conclusion, these findings identify a new function for miR-129 as a potent inducer of autophagy through a novel Notch-1/E2F7/Beclin-1 axis in glioma.

E2F7 overexpression leads to tamoxifen resistance in breast cancer cells by competing with E2F1 at miR-15a/16 promoter

About 50-70% of breast cancers are estrogen receptor α (ERα) positive and most of them are sensitive to endocrine therapy including tamoxifen. However, one third of these patients will eventually develop resistance and relapse. We found that the expression of miR-15a and miR-16 were significantly decreased in tamoxifen resistant ER positive breast cancer cell lines. Exogenous expression of miR-15a/16 mimics re-sensitized resistant cells to tamoxifen by inhibiting Cyclin E1 and B cell lymphoma-2 (Bcl-2) to induce cell growth arrest and apoptosis respectively. Further, we identified that a repressive member of E2F family, E2F7, was responsible for the suppression of miR-15a/16 cluster by competing with E2F1 for E2F binding site at the promoter of their host gene DLEU2. Moreover, high expression of E2F7 is correlated with high risk of relapse and poor prognosis in breast cancer patients receiving tamoxifen treatment. Together, our results suggest that overexpression of E2F7 represses miR-15a/16 and then increases Cyclin E1 and Bcl-2 that result in tamoxifen resistance. E2F7 may be a valuable prognostic marker and a therapeutic target of tamoxifen resistance in breast cancer.

Elevated E2F7 expression predicts poor prognosis in human patients with gliomas

E2F transcription factors have been studied extensively in a broad range of organisms as major regulators of cell cycle, apoptosis, and differentiation. The E2F family includes the atypical member E2F7, which has been rarely studied in gliomas. The aim of this study is to determine the expression status of E2F7 in gliomas, its relationship to clinicopathological features, and patients' outcome. The mRNA levels of E2F7 in the human brain and different grades of gliomas were analysed using datasets from the publically available Oncomine database. One of the most significant co-expression factors, CDK1, together with E2F7, was further validated by immunohistochemistry in 90 different grades of gliomas. Furthermore, univariate and multivariate analyses were performed to identify prognostic variables relative to patient and tumour characteristics and treatment modalities. E2F7 mRNA expression was found to be elevated in gliomas by Oncomine-database analysis. Immunohistochemistry showed an increase in E2F7 labelling index in high- versus low-grade gliomas (62.1±11.8% vs. 18.9±10.2%, p<0.0001). There was a positive correlation between E2F7 and CDK1 immunoreactivity (Spearman r=0.446, p=0.037). Clinicopathological evaluation suggested that E2F7 expression was associated with tumour grade (p<0.0001) and recurrence (p=0.025). In Cox multivariate analysis, pathological classification and recurrence were independent prognostic factors of gliomas, and E2F7 was significantly related to progression-free survival (p=0.011), but not overall survival (p=0.062). Our findings suggested that E2F7 might act as an independent prognostic factor of gliomas and might constitute a potential therapeutic target for this disease.

High-resolution molecular validation of self-renewal and spontaneous differentiation in clinical-grade adipose-tissue derived human mesenchymal stem cells

Improving the effectiveness of adipose-tissue derived human mesenchymal stromal/stem cells (AMSCs) for skeletal therapies requires a detailed characterization of mechanisms supporting cell proliferation and multi-potency. We investigated the molecular phenotype of AMSCs that were either actively proliferating in platelet lysate or in a basal non-proliferative state. Flow cytometry combined with high-throughput RNA sequencing (RNASeq) and RT-qPCR analyses validate that AMSCs express classic mesenchymal cell surface markers (e.g., CD44, CD73/NT5E, CD90/THY1, and CD105/ENG). Expression of CD90 is selectively elevated at confluence. Self-renewing AMSCs express a standard cell cycle program that successively mediates DNA replication, chromatin packaging, cyto-architectural enlargement, and mitotic division. Confluent AMSCs preferentially express genes involved in extracellular matrix (ECM) formation and cellular communication. For example, cell cycle-related biomarkers (e.g., cyclins E2 and B2, transcription factor E2F1) and histone-related genes (e.g., H4, HINFP, NPAT) are elevated in proliferating AMSCs, while ECM genes are strongly upregulated (>10-fold) in quiescent AMSCs. AMSCs also express pluripotency genes (e.g., POU5F1, NANOG, KLF4) and early mesenchymal markers (e.g., NES, ACTA2) consistent with their multipotent phenotype. Strikingly, AMSCs modulate expression of WNT signaling components and switch production of WNT ligands (from WNT5A/WNT5B/WNT7B to WNT2/WNT2B), while upregulating WNT-related genes (WISP2, SFRP2, and SFRP4). Furthermore, post-proliferative AMSCs spontaneously express fibroblastic, osteogenic, chondrogenic, and adipogenic biomarkers when maintained in confluent cultures. Our findings validate the biological properties of self-renewing and multi-potent AMSCs by providing high-resolution quality control data that support their clinical versatility.

CtBP2 proteome: Role of CtBP in E2F7-mediated repression and cell proliferation

C-terminal binding protein (CtBP) family transcriptional corepressors include CtBP1 and CtBP2. While CtBP1 and CtBP2 share significant amino acid sequence homology, CtBP2 possesses a unique N-terminal domain that is modified by acetylation and contributes to exclusive nuclear localization. Although CtBP1 and CtBP2 are functionally redundant for certain activities during vertebrate development, they also perform unique functions. Previous studies have identified several CtBP1-interacting proteins that included other transcriptional corepressors, DNA-binding repressors and histone modifying enzymatic components such as the histone deacetylases and the histone demethylase LSD-1. Here, we carried out an unbiased proteomic analysis of CtBP2-associated proteins and discovered the association of several components of the CtBP1 proteome as well as novel interactions. The CtBP2 proteome contained components of the NuRD complex and the E2F family member E2F7. E2F7 interacted with the hydrophobic cleft region of CtBP1 and CtBP2 through a prototypical CtBP binding motif, PIDLS. E2F7 repressed E2F1 transcription, inhibited cell proliferation in a CtBP-dependent fashion. Our study identified CtBP as a corepressor of E2F7 and as a regulator of DNA damage response.

Unbiased transcriptome signature of in vivo cell proliferation reveals pro- and antiproliferative gene networks

Different types of mature B-cell lymphocytes are overall highly similar. Nevertheless, some B cells proliferate intensively, while others rarely do. Here, we demonstrate that a simple binary classification of gene expression in proliferating vs. resting B cells can identify, with remarkable selectivity, global in vivo regulators of the mammalian cell cycle, many of which are also post-translationally regulated by the APC/C E3 ligase. Consequently, we discover a novel regulatory network between the APC/C and the E2F transcription factors and discuss its potential impact on the G1-S transition of the cell cycle. In addition, by focusing on genes whose expression inversely correlates with proliferation, we demonstrate the inherent ability of our approach to also identify in vivo regulators of cell differentiation, cell survival, and other antiproliferative processes. Relying on data sets of wt, non-transgenic animals, our approach can be applied to other cell lineages and human data sets.