E2F1: a promising regulator in ovarian carcinoma

E2F1 mediates competition, proliferation and response to cisplatin in cohabitating resistant and sensitive ovarian cancer cells

Background

Tumor heterogeneity is one of the key factors leading to chemo-resistance relapse. It remains unknown how resistant cancer cells influence sensitive cells during cohabitation and growth within a heterogenous tumors. The goal of our study was to identify driving factors that mediate the interactions between resistant and sensitive cancer cells and to determine the effects of cohabitation on both phenotypes.

Methods

We used isogenic ovarian cancer (OC) cell lines pairs, sensitive and resistant to platinum: OVCAR5 vs. OVCAR5 CisR and PE01 vs. PE04, respectively, to perform long term direct culture and to study the phenotypical changes of the interaction of these cells.

Results

Long term direct co-culture of sensitive and resistant OC cells promoted proliferation (p < 0.001) of sensitive cells and increased the proportion of cells in the G1 and S cell cycle phase in both PE01 and OVCAR5 cells. Direct co-culture led to a decrease in the IC50 to platinum in the cisplatin-sensitive cells (5.92 µM to 2.79 µM for PE01, and from 2.05 µM to 1.51 µM for OVCAR5). RNAseq analysis of co-cultured cells showed enrichment of Cell Cycle Control, Cyclins and Cell Cycle Regulation pathways. The transcription factor E2F1 was predicted as the main effector responsible for the transcriptomic changes in sensitive cells. Western blot and qRT-PCR confirmed upregulation of E2F1 in co-cultured vs monoculture. Furthermore, an E2F1 inhibitor reverted the increase in proliferation rate induced by co-culture to baseline levels.

Conclusion

Our data suggest that long term cohabitation of chemo-sensitive and -resistant cancer cells drive sensitive cells to a higher proliferative state, more responsive to platinum. Our results reveal an unexpected effect caused by direct interactions between cancer cells with different proliferative rates and levels of platinum resistance, modelling competition between cells in heterogeneous tumors.

E2F3/5/8 serve as potential prognostic biomarkers and new therapeutic direction for human bladder cancer

OBJECTS

Human bladder cancer (BC) is the most common urogenital system malignancy. E2F transcription factors (E2Fs) have been reported to be involved in the growth of various cancers. However, the expression patterns, prognostic value and immune infiltration in the tumor microenvironment of the 8 E2Fs in BC have yet fully to be explored.

METHODS AND STRATEGY

We investigated the differential expression of E2Fs in BC patients, the prognostic value and correlation with immune infiltration by analyzing a range of databases.

RESULTS

We found that the mRNA expression levels of E2F1/2/3/4/5/7/8 were significantly higher in BC patients than that of control tissues. And the increased mRNA expression levels of all E2Fs were associated with tumor stage of BC. The survival analysis revealed that the elevated mRNA expression levels of E2F3/5/8 were significantly correlated with the overall survival (OS) of BC patients. And the genetic changes of E2Fs in BC patients were associated with shorter overall survival (OS) and progression-free survival (PFS). In addition, we revealed that the E2F3/5/8 expressions were closely correlated with tumor-infiltrating lymphocytes (TILs).

CONCLUSIONS

E2F3/5/8 might serve as promising prognostic biomarkers and new therapeutic direction for BC patients.

Partner of NOB1 homolog transcriptionally activated by E2F transcription factor 1 promotes the malignant progression and inhibits ferroptosis of pancreatic cancer

Pancreatic cancer (PC) is one of the deadliest malignancies. Partner of NOB1 homolog (PNO1) has been reported to be involved in tumorigenesis. However, the role of PNO1 in PC remains to be elucidated. The purpose of this study was to examine the effects of PNO1 on the progression of PC and the possible mechanism related to E2F transcription factor 1 (E2F1), a transcription factor predicted by the JASPAR database to bind to the PNO1 promoter region and promoted the proliferation of pancreatic ductal adenocarcinoma. First, PNO1 expression in PC tissues and its association with survival rate were analyzed by the Gene Expression Profiling Interactive Analysis database. Western blot and reverse transcription-quantitative polymerase chain reaction were used to evaluate PNO1 expression in several PC cell lines. After PNO1 silencing, cell proliferation, migration, and invasion were measured by colony formation assay, 5-ethynyl-2'-deoxyuridine staining, wound healing, and transwell assays. Then, the lipid reactive oxygen species in PANC-1 cells was estimated by using C11-BODIPY581/591 probe. The levels of glutathione, malondialdehyde, and iron were measured. The binding between PNO1 and E2F1 was confirmed by luciferase and chromatin immunoprecipitation (ChIP) assays. Subsequently, E2F1 was overexpressed in PANC-1 cells with PNO1 knockdown to perform the rescue experiments. Results revealed that PNO1 was highly expressed in PC tissues and PNO1 expression was positively correlated with overall survival rate and disease-free survival rate. Significantly elevated PNO1 expression was also observed in PC cell lines. PNO1 knockdown inhibited the proliferation, migration, and invasion of PANC-1 cells. Moreover, ferroptosis was promoted in PNO1-silenced PANC-1 cells. Results of luciferase and ChIP assays indicated that E2F1 could bind to PNO1 promoter region. Rescue experiments suggested that E2F1 overexpression reversed the impacts of PNO1 depletion on the malignant behaviors and ferroptosis in PANC-1 cells. Summing up, PNO1 transcriptionally activated by E2F1 promotes the malignant progression and inhibits the ferroptosis of PC.

Esomeprazole Alleviates Cisplatin Resistance by Inhibiting the AKT/mTOR Pathway in Ovarian Cancer Cells

Purpose

Ovarian cancer is the most lethal malignancy in gynecology. Due to limited treatment strategies and platinum resistance, newer drugs and therapeutic options are needed. Esomeprazole (ESO) has been reported to have multiple anticancer activities in preclinical and clinical research. Therefore, this study aimed to explore the anticancer effects of esomeprazole on ovarian cancer and its underlying molecular mechanisms.

Methods

CCK-8 and 5-ethynyl-2'-deoxyuridine (EdU) assays were used to detect cell viability and proliferation. The Transwell assay was used to evaluate cell migration and invasion capacity. Flow cytometry was used to detect cell apoptosis. Western blotting and immunofluorescence were used to detect protein expression.

Results

ESO effectively inhibited the cell viability, proliferation, invasion, migration, and induced apoptosis of ovarian cancer cells in a concentration-dependent manner. Treatment with ESO decreased the expression of c-MYC, SKP2, E2F1, N-cadherin, vimentin, and matrix metalloproteinase 2 (MMP2), while it increased E-cadherin, caspase3, p53, BAX, and cleaved poly (ADP-ribose) polymerase (PARP) expression, and downregulated the PI3K/AKT/mTOR signaling pathway. Furthermore, ESO combined with cisplatin showed synergistic effects in inhibiting proliferation, invasion, and migration of cisplatin-resistant ovarian cancer cells. The mechanism may be related to the increased inhibition of c-MYC, epithelial-mesenchymal transition (EMT), and the AKT/mTOR signaling pathway and enhanced the upregulation of the pro-apoptotic protein BAX and cleaved PARP levels. Moreover, ESO combined with cisplatin synergistically upregulated the expression of the DNA damage marker γH2A.X.

Conclusion

ESO exerts multiple anticancer activities and has a synergistic effect in combination with cisplatin on cisplatin-resistant ovarian cancer cells. This study provides a promising strategy to improve chemosensitivity and overcome resistance to cisplatin in ovarian cancer.

Inferring cancer common and specific gene networks via multi-layer joint graphical model

Cancer is a complex disease caused primarily by genetic variants. Reconstructing gene networks within tumors is essential for understanding the functional regulatory mechanisms of carcinogenesis. Advances in high-throughput sequencing technologies have provided tremendous opportunities for inferring gene networks via computational approaches. However, due to the heterogeneity of the same cancer type and the similarities between different cancer types, it remains a challenge to systematically investigate the commonalities and specificities between gene networks of different cancer types, which is a crucial step towards precision cancer diagnosis and treatment. In this study, we propose a new sparse regularized multi-layer decomposition graphical model to jointly estimate the gene networks of multiple cancer types. Our model can handle various types of gene expression data and decomposes each cancer-type-specific network into three components, i.e., globally shared, partially shared and cancer-type-unique components. By identifying the globally and partially shared gene network components, our model can explore the heterogeneous similarities between different cancer types, and our identified cancer-type-unique components can help to reveal the regulatory mechanisms unique to each cancer type. Extensive experiments on synthetic data illustrate the effectiveness of our model in joint estimation of multiple gene networks. We also apply our model to two real data sets to infer the gene networks of multiple cancer subtypes or cell lines. By analyzing our estimated globally shared, partially shared, and cancer-type-unique components, we identified a number of important genes associated with common and specific regulatory mechanisms across different cancer types.

Proteogenomic insights into the biology and treatment of pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with poor prognosis. Proteogenomic characterization and integrative proteomic analysis provide a functional context to annotate genomic abnormalities with prognostic value.

METHODS

We performed an integrated multi-omics analysis, including whole-exome sequencing, RNA-seq, proteomic, and phosphoproteomic analysis of 217 PDAC tumors with paired non-tumor adjacent tissues. In vivo functional experiments were performed to further illustrate the biological events related to PDAC tumorigenesis and progression.

RESULTS

A comprehensive proteogenomic landscape revealed that TP53 mutations upregulated the CDK4-mediated cell proliferation process and led to poor prognosis in younger patients. Integrative multi-omics analysis illustrated the proteomic and phosphoproteomic alteration led by genomic alterations such as KRAS mutations and ADAM9 amplification of PDAC tumorigenesis. Proteogenomic analysis combined with in vivo experiments revealed that the higher amplification frequency of ADAM9 (8p11.22) could drive PDAC metastasis, though downregulating adhesion junction and upregulating WNT signaling pathway. Proteome-based stratification of PDAC revealed three subtypes (S-I, S-II, and S-III) related to different clinical and molecular features. Immune clustering defined a metabolic tumor subset that harbored FH amplicons led to better prognosis. Functional experiments revealed the role of FH in altering tumor glycolysis and in impacting PDAC tumor microenvironments. Experiments utilizing both in vivo and in vitro assay proved that loss of HOGA1 promoted the tumor growth via activating LARP7-CDK1 pathway.

CONCLUSIONS

This proteogenomic dataset provided a valuable resource for researchers and clinicians seeking for better understanding and treatment of PDAC.

Comprehensive Analysis of the E2F Transcription Factor Family in Human Lung Adenocarcinoma

Background

E2F transcription factors (E2Fs), code a family of pivotal transcription factors, have been identified as key regulators in tumor tumorigenesis. However, the function of E2F family in human lung adenocarcinoma (LUAD) have not been fully elucidated.

Methods

Herein, The Cancer Genome Atlas (TCGA) databases, Kaplan-Meier plotter, cBioPortal and TIMER were used to analyze differential expression, prognostic value, genetic alteration and immune cell infiltration of E2Fs in LUAD patients.

Results

The expression levels of E2Fs (E2F1-8) were all significantly upregulated in LUAD tissues compared with normal lung tissues. All eight E2Fs had low rates of gene mutation in LUAD patients from cBioPortal databases. Survival analysis revealed that E2F2 (P=0.038; HR 1.36; 95% CI 1.02–1.81), E2F7 (P<0.001; HR 1.78; 95% CI 1.33–2.39) and E2F8 (P=0.03; HR 1.37; 95% CI 1.02–1.82) were significantly associated with poor prognosis. Multivariate cox regression analysis found that only E2F7 (P<0.001; HR 2.72; 95% CI 1.75–4.25) was an independent prognostic predictor in LUAD after adjusting common clinical parameters. The receiver operating characteristic (ROC) analysis also found that E2F7 had high diagnostic value for LUAD (AUC=0.901). Further analysis found that E2F7 was significantly associated with LUAD immune cell infiltration of B cell, T cell, neutrophil, and myeloid dendritic cell. E2F7 also have positive correlations with immune checkpoint genes including SIGLEC15, CD274, HAVCR2, PDCD1LG2, CTLA4, TIGIT, LAG3 and PDCD1 in LUAD.

Conclusion

Our findings showed various association of E2F7 in LUAD diagnostic and prognostic aspects, which suggested its potential in becoming a novel biomarker.

Genetic Polymorphism of E2F1 Influences Susceptibility to Ovarian Cancer in a Chinese Population

Purpose

The present study is aimed at exploring whether rs3213172, rs3213173, and rs3213176 polymorphisms of the E2F1 gene confer risk for ovarian cancer.

Methods

A total of 80 patients with ovarian cancer were selected from the first affiliated hospital of Soochow University in Jiangsu Province from January 2016 to June 2021, including 48 cases that were premenopausal and 32 cases that were menopausal. 130 healthy women who participated in normal physical examinations during the same period were selected as the control group. The rs3213172, rs3213173, and rs3213176 polymorphisms of the E2F1 gene were detected by the fluorescent probe method.

Results

For rs3213173 and rs3213176 loci, there were no statistical significances in genotype distribution frequency between the ovarian cancer group and the control group (P > 0.05). For rs3213172 loci, a significant difference was observed in CT genotype between the ovarian cancer group and the control group (P=0.024).

Conclusion

E2F1 gene rs3213173 and rs3213176 polymorphisms confer no risk to ovarian cancer risk. The CT genotype of E2F1 gene rs3213172 polymorphism is associated with an increased risk of ovarian cancer, and E2F1 gene rs3213172 polymorphism may be a novel marker for the risk prediction of ovarian cancer.

Comprehensive analysis of the functional and prognostic value of E2F transcription factors in human prostate cancer through data mining and experimental validation

Background

A growing body of evidence shows that E2F transcription factors play a significant role in the tumorigenesis of prostate cancer. However, their functional and prognostic value has not been fully illustrated. Therefore, we used bioinformatics methods to further analyze the possible roles of E2F transcription factors in the development and progression of prostate cancer.

Methods

We explored the expression levels of E2F transcription factors using data from The Cancer Genome Atlas (TCGA) and Oncomine database in paired and unpaired samples. The clinical correlation and prognostic value of E2F transcription factors were assessed. Using the R package “pROC”, we judged the diagnostic value of E2F transcription factors. The online website tool cBioPortal was also employed to find possible gene alterations of E2F transcription factors in samples from TCGA. The R package “clusterprofiler” was used to conduct functional analysis. Moreover, we also used the Tumor Immune Estimation Resource to search for the associations between E2F transcription factors and the infiltration levels of 6 kinds of immune cells. Finally, quantitative real-time polymerase chain reaction (PCR) was conducted to validate the expression levels of E2F transcription factors in human paired prostate tissues.

Results

E2F1/2/3/5 messenger RNA (mRNA) expression levels were higher in prostate cancer tissues than in normal tissues, while E2F4 and E2F6 mRNA expression levels were lower (P<0.05). All E2F transcription factors were associated with clinical parameters. Kaplan-Meier analysis revealed that E2F1/4/6/8 were notably associated with the overall survival of patients with prostate cancer (P<0.05). Receiver operating characteristic (ROC) curve results showed that except for E2F7, the other E2F transcription factors had diagnostic value for prostate cancer (P<0.05). We further found close associations between E2F transcription factors and the infiltration levels of immune cells. The results of quantitative real-time PCR were consistent with those from public databases.

Conclusions

E2F transcription factor family members are differentially expressed in prostate cancer and are significantly related to the prognosis of patients, suggesting that they may be adopted as biomarkers for prognosis prediction and the treatment of prostate cancer.

RNA biomarkers from proximal liquid biopsy for diagnosis of ovarian cancer

BACKGROUND

Most ovarian cancer patients are diagnosed at an advanced stage and have a high mortality rate. Current screening strategies fail to improve prognosis because markers that are sensitive for early stage disease are lacking. This medical need justifies the search for novel approaches using utero-tubal lavage as a proximal liquid biopsy.

METHODS

In this study, we explore the extracellular transcriptome of utero-tubal lavage fluid obtained from 26 ovarian cancer patients and 48 controls using messenger RNA (mRNA) capture and small RNA sequencing.

RESULTS

We observed an enrichment of ovarian and fallopian tube specific messenger RNAs in utero-tubal lavage fluid compared to other human biofluids. Over 300 mRNAs and 41 miRNAs were upregulated in ovarian cancer samples compared with controls. Upregulated genes were enriched for genes involved in cell cycle activation and proliferation, hinting at a tumor-derived signal.

CONCLUSION

This is a proof-of-principle that mRNA capture sequencing of utero-tubal lavage fluid is technically feasible, and that the extracellular transcriptome of utero-tubal lavage should be further explored in larger cohorts to assess the diagnostic value of the biomarkers identified in this study.

IMPACT

Proximal liquid biopsy from the gynecologic tract is a promising source for mRNA and miRNA biomarkers for diagnosis of early-stage ovarian cancer.

Metformin Affects the Transcriptomic Profile of Chicken Ovarian Cancer Cells

Ovarian cancer is the most lethal gynecological malignancy in women. Metformin intake is associated with a reduced incidence of ovarian cancer and increased overall survival rate. We determined the effect of metformin on sphere formation, extracellular matrix invasion, and transcriptome profile of ovarian cancer cells (COVCAR) isolated from ascites of chickens that naturally developed ovarian cancer. We found that metformin treatment significantly decreased sphere formation and invasiveness of COVCAR cells. RNA-Seq data analysis revealed 0, 4, 365 differentially expressed genes in cells treated with 0.5, 1, 2 mM metformin, respectively compared to controls. Transcriptomic and ingenuity pathway analysis (IPA) revealed significant downregulation of MMP7, AICDA, GDPD2, APOC3, APOA1 and predicted inhibition of upstream regulators NFKB, STAT3, TP53 that are involved in epithelial-mesenchymal transition, DNA repair, and lipid metabolism. The analysis revealed significant upregulation of RASD2, IHH, CRABP-1 and predicted activation of upstream regulators VEGF and E2F1 that are associated with angiogenesis and cell cycle. Causal network analysis revealed novel pathways suggesting predicted inhibition of ovarian cancer through master regulator ASCL1 and dataset genes DCX, SEMA6B, HEY2, and KCNIP2. In summary, advanced pathway analysis in IPA revealed novel target genes, upstream regulators, and pathways affected by metformin treatment of COVCAR cells.

Meta-analysis identifying epithelial-derived transcriptomes predicts poor clinical outcome and immune infiltrations in ovarian cancer

BACKGROUND

Previous studies revealed that the epithelial component is associated with the modulation of the ovarian tumor microenvironment (TME). However, the identification of key transcriptional signatures of laser capture microdissected human ovarian cancer epithelia remains lacking.

METHODS

We identified the differentially expressed transcriptional signatures of human ovarian cancer epithelia by meta-analysis of GSE14407, GSE2765, GSE38666, GSE40595, and GSE54388. Then we investigated the enrichment of KEGG pathways that are associated with epithelia-derived transcriptomes. Finally, we investigated the correlation of key epithelia-hub genes with the survival prognosis and immune infiltrations. Finally, we investigated the genetic alterations of key prognostic hub genes and their diagnostic efficacy in ovarian cancer epithelia.

RESULTS

We identified 1339 differentially expressed genes (DEGs) in ovarian cancer epithelia including 541upregulated and 798 downregulated genes. We identified 21 (such as E2F4, FOXM1, TFDP1, E2F1, and SIN3A) and 11 (such as JUN, DDX4, FOSL1, NOC2L, and HMGA1) master transcriptional regulators (MTRs) that are interacted with upregulated and the downregulated genes in ovarian tumor epithelium, respectively. The STRING-based analysis identified hub genes (such as CDK1, CCNB1, AURKA, CDC20, and CCNA2) in ovarian cancer epithelia. The significant clusters of identified hub genes are associated with the enrichment of KEGG pathways including cell cycle, DNA replication, cytokine-cytokine receptor interaction, pathways in cancer, and focal adhesion. The upregulation of SCNN1A and CDCA3 and the downregulation of SOX6 are correlated with a shorter survival prognosis in ovarian cancer (OV). The expression level of SOX6 is negatively correlated with immune score and positively correlated with tumor purity in OV. Moreover, SOX6 is negatively correlated with the infiltration of TILs, CD8+ T cells, CD4+ Regulatory T cells, cytolytic activity, T cell activation, pDC, neutrophils, and macrophages in OV. Also, SOX6 is negatively correlated with various immune markers including CD8A, PRF1, GZMA, GZMB, NKG7, CCL3, and CCL4, indicating the immune regulatory efficiency of SOX6 in the TME of OV. Furthermore, SCNN1A, CDCA3, and SOX6 genes are genetically altered in OV and the expression levels of SCNN1A and SOX6 genes showed diagnostic efficacy in ovarian cancer epithelia.

CONCLUSIONS

The identified ovarian cancer epithelial-derived key transcriptional signatures are significantly correlated with survival prognosis and immune infiltrations, and may provide new insight into the diagnosis and treatment of epithelial ovarian cancer.

Expression and prognostic value of E2F3 transcription factor in non-small cell lung cancer

E2F transcription factor 3 (E2F3) plays a vital role in the development of various types of cancer. To verify whether E2F3 is a suitable biomarker for the prognosis of lung cancer, bioinformatics analysis was performed to determine the differential expression level of E2F3 in lung cancer and the surrounding non-tumor tissues, and the results were confirmed in a NSCLC cell line and a tissue microarray (TMA). The relevance of E2F3 in non-small cell lung cancer (NSCLC) was investigated in 19 studies from the Oncomine database and confirmed in The Cancer Genome Atlas database. In the lung cancer cell line A549, the inhibition of E2F3 mRNA expression level led to decreased tumor cell viability and cell migration, which was determined by a Cell Counting Kit-8 and wound healing assays, respectively. Immunohistochemistry analyses of E2F3, Bcl-2, Bax and caspase-3 were performed in the NSCLC TMA (n=50). The assessment of TMA detected the increase of E2F3 protein expression level in the tumor tissues, as compared with that in the non-tumor tissues, which was also correlated with the increase in expression of Bcl-2 in tumors. Analysis of the clinical data from patients with NSCLC revealed that the overexpression of E2F3 was associated with early lymphatic spreading, and poor patient survival time. The OncomiR website was used to predict the E2F3 upstream microRNAs and determine their prognostic value in patients with NSCLC. The results from the present study revealed that E2F3 was overexpressed at both the transcriptional and translational levels in NSCLC tissues, as compared with that in non-tumor tissues. The overexpression of E2F3 was associated with the upregulation of the anti-apoptotic factor, Bcl-2, which may contribute to uncontrolled tumor growth. Thus, E2F3 was shown to have important oncogenic properties in the development of NSCLC, and it may become a potential biomarker for patients with NSCLC.

Comprehensive Analysis of Prognostic and Immune Infiltrates for E2F Transcription Factors in Human Pancreatic Adenocarcinoma

Background

E2F transcription factors (E2Fs) are a group of genes encoding a family of transcription factors in higher eukaryotes. They are involved in a variety of cellular functions and are up-regulated in many tissues and organs. However, the expression level, genetic variation, molecular mechanism, and biological function of different E2Fs in PAAD and its relationship with the prognosis and immune infiltration in patients with PAAD have not been fully elucidated.

Methods

In this study, we investigated the mRNA expression level, genetic variation, prognostic value and gene–gene interaction network of E2Fs in PAAD using the Oncomine, GEPIA, Kaplan Meier plotter, cBioPortal, GeneMANIA, STRING and Metascape database. Then, the relationship between E2Fs expression and tumor immune invasion was studied by using the TIMER database. Finally, we confirmed the expression of E2Fs in PAAD by IHC.

Results

The transcription levels of E2F1/3/5/8 are obviously up-regulated in PAAD and the high expression of E2F2/3/6/8 was apparently associated with the tumor stage of patients with PAAD. The abnormal expression of E2F1/2/3/4/5/7/8 in PAAD patients is related to the clinical outcome of PAAD patients. We also found that PAAD tissues have higher expression levels of E2F1/3/5/8 compared with adjacent normal tissues. The function of E2Fs and its neighboring genes is mainly related to the transcription initiation of the RNA polymerase II promoter. The functions of E2Fs and its neighboring proteins are mainly related to cell cycle, virus carcinogenesis, FoxO signaling pathway, TGF-β signaling pathway, transcriptional disorders in cancer and Wnt signaling pathway. We also found that the expression of E2Fs was significantly correlated with immune infiltrates, including B cells, CD8+ T cells, CD4+T cells, neutrophils, macrophages, and dendritic cells.

Conclusions

Our study may provide new insights into the choice of immunotherapy targets and prognostic biomarkers in PAAD patients.

[Advancement of E2F1 in Common Tumors]

细胞周期相关转录因子E2F1（E2F transcription factor 1）是细胞周期相关转录因子E2F家族成员之一，主要参与包括细胞周期进展、DNA修复、DNA复制、细胞分化，增殖和凋亡等多种细胞过程。E2F1在全身多种肿瘤组织和细胞中呈高表达，起着促癌基因的作用，E2F1表达上调与肿瘤的发生、发展、转移及预后密切相关。因此，E2F1有望成为肿瘤治疗的新靶点。本文就E2F1在目前常见肿瘤中的最新研究进展做一综述。

RPL21 siRNA Blocks Proliferation in Pancreatic Cancer Cells by Inhibiting DNA Replication and Inducing G1 Arrest and Apoptosis

Background

Our previous study showed that the ribosomal protein L21 (RPL21) may play an important role in the development and survival of pancreatic cancer. In this article, RNA interference (RNAi) experiments were performed with RPL21-specific small interfering RNA (siRNA) to elucidate the mechanism by which RPL21 controls PC PANC-1 and BxPC-3 cell proliferation.

Methods

In the present study, PANC-1, BxPC-3 cells, and BALB/c nude mice were used to investigate antitumor effect and mechanism by which RPL21 controls cell proliferation and apoptosis in vitro and in vivo. The effects of RPL21 knockdown on PANC-1 and BxPC-3 cell proliferation, cell cycle and cell apoptosis in vitro were determined using 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assays and flow cytometry assay. The mechanism of RPL21 regulating cell proliferation was investigated using transcriptome sequencing analysis and luciferase reporter assay. The effects of RPL21 knockdown on PANC-1 and BxPC-3 cell proliferation in vivo were determined using BALB/c nude mice tumor model.

Results

In PANC-1 and BxPC-3 cells, the knockdown of RPL21 expression with corresponding siRNA suppressed cell proliferation in vitro and in vivo, inhibited DNA replication, and induced arrests in the G1 phase of the cell cycle. Further results showed that the mini-chromosome maintenance (MCM) protein family (MCM2-7), CCND1 and CCNE1 were down-regulated significantly in PANC-1 and BxPC-3 cells after transfected with RPL21 siRNA, which suggests that the suppression of DNA replication is due to the reduced expression of MCM2-7 family, and the induction of G1 arrest is correlated with the inhibition of CCND1 and CCNE1. Luciferase reporter assay showed that RPL21 controls the DNA replication and G1-S phase progression possibly through the regulation of E2F1 transcription factor in PC cells. Moreover, RPL21 siRNA showed an apoptosis-inducing effect only in BxPC-3 and PANC-1 cells but not in normal HPDE6-C7 cells. The increase of caspase-8 activities and the loss of mitochondrial membrane potential after RPL21 silencing indicates that the RPL21 gene may be involved in caspase-8-related mitochondrial apoptosis.

Conclusion

Our findings suggest that siRNA against the RPL21 gene possesses a potential anti-cancer activity for PC cells by inhibiting their proliferation and DNA replication, as well as inducing cell cycle G1 arrest and cell apoptosis.

The anti-tumourigenic effect of ellagic acid in SKOV-3 ovarian cancer cells entails activation of autophagy mediated by inhibiting Akt and activating AMPK

This study investigated the effect of ellagic acid (EA) on SKOV-3 cell growth and invasiveness and tested if the underlying mechanism involves modulating autophagy. Cells were treated with EA in the presence or absence of chloroquine (CQ), an autophagy inhibitor, compound C (CC), an AMPK inhibitor, or an insulin-like growth factor-1 (IGF-1), a PI3K/Akt activator. EA, at an IC₅₀ of 36.6 µmol/L, inhibited cell proliferation, migration, and invasion and induced cell apoptosis in SKOV-3 cells. These events were prevented by CQ. Also, EA increased levels of Beclin-1, ATG-5, LC3I/II, Bax, cleaved caspase-3/8 and reduced those of p62 and Bcl-2 in these cancer cells. Mechanistically, EA decreased levels of p-S6K1 (Thr³⁸⁹ ) and 4EBP-1 (Thr^37/46 ), two downstream targets of mTORC1, and p-Akt (Thr³⁰⁸ ) but increased levels of AMPK (Thr¹⁷² ) and p-raptor (Ser⁷⁹² ), a natural inhibitor of mTORC1. CC or IGF-1 alone partially prevented the effect of EA on cell survival, cell invasions, and levels of LDH, Beclin-1, and cleaved caspase-3. In conclusion, EA can inhibit SKOV-3 growth, migration, and invasion by activating cytotoxic autophagy mediated by inhibition of mTORC1 and Akt and activation of AMPK.

Dynamic TF-lncRNA Regulatory Networks Revealed Prognostic Signatures in the Development of Ovarian Cancer

The pathological development of ovarian cancer (OC) is a complex progression that depends on multiple alterations of coding and non-coding genes. Therefore, it is important to capture the transcriptional-regulating events during the progression of OC development and to identify reliable markers for predicting clinical outcomes in patients. A dataset of 399 ovarian serous cystadenocarcinoma patients at different stages from The Cancer Genome Atlas (TCGA) was analyzed. Stage-specific transcription factor (TF)-long non-coding RNA (lncRNA) regulatory networks were constructed by integrating high-throughput RNA molecular profiles and TF binding information. Systematic analysis was performed to characterize the TF-lncRNA-regulating behaviors across different stages of OC. Cox regression analysis and Kaplan-Meier survival curves were used to evaluate the prognostic efficiency of TF-lncRNA regulations and cliques. The stage-specific TF-lncRNA regulatory networks at three OC stages (II, III, and IV) exhibited common structures and specific topologies of risk TFs and lncRNAs. A TF-lncRNA activity profile across different stages revealed that TFs were highly stage-selective in regulating lncRNAs. Functional analysis indicated that groups of TF-lncRNA interactions were involved in specific pathological processes in the development of OC. In a STAT3-FOS co-regulating clique, the TFs STAT3 and FOS were selectively regulating target lncRNAs across different OC stages. Further survival analysis indicated that this TF-lncRNA biclique may have the potential for predicting OC prognosis. This study revealed the topological and dynamic principles of TF-lncRNA regulatory networks and provided a resource for further analysis of stage-specific regulating mechanisms of OC.

Regulation of the transcription factor E2F1 mRNA in ovarian granulosa cells of cattle

The E2F family of transcription factors plays an important role in the control of the cell cycle, cell proliferation, and differentiation, and their role in ovarian function is just emerging. Although some evidence suggests a possible role of E2F1 in ovarian follicular development, what regulates its production in ovarian cells is unknown. Objectives of this study were to determine whether: (i) E2F1 gene expression in granulosa cells (GCs) and theca cells (TCs) change with follicular development and (ii) E2F1 mRNA abundance in TC and GC is hormonally regulated. Using real-time PCR, E2F1 mRNA abundance in GC was 5.5-fold greater (P < 0.05) in small (SM; 1 to 5 mm) than large (LG; >8 mm) follicles, but in TC, E2F1 expression did not differ among follicle sizes. SM-follicle GC had 2.1-fold greater (P < 0.05) E2F1 mRNA than TC. In SM-follicle GC, FGF9 induced a 7.6-fold increase in E2F1 mRNA abundance; however, FGF9 did not affect (P > 0.10) abundance of E2F1 mRNA in LG-follicle TC or GC. Follicle-stimulating hormone (FSH) had no effect (P > 0.10) on E2F1 gene expression in SM- or LG-follicle GC. SM-follicle GC were concomitantly treated with insulin-like growth factor 1 (30 ng/mL), FSH (30 ng/mL), and either 0 or 30 ng/mL of FGF9 with or without 50 µM of an E2F inhibitor (E2Fi; HLM0064741); FGF9 alone increased (P < 0.05) GC numbers, whereas E2Fi alone decreased (P < 0.05) GC numbers, and concomitant treatment of E2Fi with FGF9 blocked (P < 0.05) this stimulatory effect of FGF9. Estradiol production was inhibited (P < 0.05) by FGF9 alone and concomitant treatment of E2Fi with FGF9 attenuated (P < 0.05) this inhibitory effect of FGF9. SM-follicle GC treated with E2Fi decreased (P < 0.05) E2F1 mRNA abundance by 70%. Collectively, our studies show that GC E2F1 mRNA is developmentally and hormonally regulated in cattle. Inhibition of E2F1 reduced FGF9-induced GC proliferation and attenuated FGF9-inhibited estradiol production, indicating that E2F1 may be involved in follicular development in cattle.

Knockout of E2F1 enhances the polarization of M2 phenotype macrophages to accelerate the wound healing process

Wound healing is a complex process, which is classically divided into inflammation, proliferation, and remodeling phases. Macrophages play a key role in wound healing, however, whether E2F1 mediates the M1/M2 polarization during the wound healing process is not known. Skin wounds were surgically induced in E2F1^-/- mice and their WT littermates. At day 2 and day 7 post-surgery, the wounded skin tissues including 2 to 3 mm normal skin were obtained. The wounded skin tissues were used for the analyses of immunofluorescence staining (CD68, iNOS, CD206), western blotting (CD68, iNOS, CD206, PPAR-γ) and Co-immunoprecipitation (E2F1-PPAR-γ interactions). E2F1^-/- mice exhibited faster wound healing process. At day 2, the M2 macrophages were remarkably increased in the E2F1^-/- mice. Surprisingly, in the border zone of the wound, E2F1^-/- mice had also more M2 macrophages and fewer M1 macrophages at day 7 post-surgery, suggesting a certain degree of polarization amongst the M1 and M2 phenotypes. Co-IP revealed that E2F1 indeed interacted with PPAR-γ, meanwhile western blotting and RT-PCR showed higher expression of PPAR-γ in the E2F1^-/- mice as compared to that in the WT mice. Therefore, the findings suggest that wound healing process could be accelerated with enhanced M2 polarization through increased PPAR-γ expression in E2F1 knockout mice.

miR-378a-5p and miR-630 induce lens epithelial cell apoptosis in cataract via suppression of E2F3

Cataract, an eye disease that threatens the health of millions of people, brings about severe economic burden for patients and society. MicroRNA (miR)-378a-5p and miR-630 were recognized as essential regulators in multiple cancers. However, the exact functions of miR-378a-5p and miR-630 in cataract are still unclear. The expression of miR-378a-5p, miR-630, and E2F transcription factor 3 (E2F3) in tissues and cells was measured by quantitative real-time polymerase chain reaction. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay was used to evaluate cell viability. Flow cytometry was conducted to analyze cell apoptosis. The interaction between E2F3 and miR-378a-5p or miR-630 was confirmed by dual-luciferase reporter assay. The expression of proteins E2F3, B cell lymphoma (Bcl-2), Bcl-2 associated X (Bax), and cleaved caspase 3 was detected by western blot assay. The expression of miR-378a-5p and miR-630 was up-regulated whereas E2F3 was down-regulated in human cataract lens tissues compared with normal lens tissues. Depletion of miR-378a-5p or miR-630 enhanced proliferation and reduced apoptosis of human lens epithelial cells. Interestingly, up-regulation of E2F3 exhibited the same trend. Next, dual-luciferase reporter assay validated the interaction between E2F3 and miR-378a-5p or miR-630. The rescue experiments further revealed that E2F3 knockdown could recover miR-378a-5p, and miR-630 inhibitor induced promotion of cell proliferation and inhibition of apoptosis in cataract. miR-378a-5p and miR-630 repressed proliferation and induced apoptosis of lens epithelial cells by targeting E2F3 in cataract, representing a prospective alternative therapy for cataract.

Vitamin D3 mediates miR-15a-5p inhibition of liver cancer cell proliferation via targeting E2F3

Vitamin D3 has been demonstrated to suppress the development and progression of liver cancer, but the mechanism is unclear. The effects of vitamin D3 and microRNA (miR)-15a-5p on liver cancer cells were investigated in the present study using MTT and colony formation assays, flow cytometry, western blotting and reverse transcription-quantitative PCR. A dual-luciferase reporter assay was performed to determine whether E2F transcription factor 3 (E2F3) was a target of miR-15a-5p. The effects of silencing the E2F3 gene expression in liver cancer cells were investigated using a small interfering RNA. Vitamin D3 suppressed liver cancer cell proliferation, induced apoptosis and increased miR-15a-5p expression. Treatment with the miR-15a-5p mimics significantly suppressed liver cancer cell proliferation compared with that of the controls. Bioinformatics analysis and a dual-luciferase reporter assay demonstrated that E2F3 was a target of miR-15a-5p and that silencing E2F3 inhibited liver cancer cell proliferation. Therefore, Vitamin D3 suppressed cell proliferation by miR-15a-5p-mediated silencing of E2F3 gene expression. These findings suggested a role for vitamin D3 and E2F3 targeting as potential novel liver cancer therapies.

E2F2/5/8 Serve as Potential Prognostic Biomarkers and Targets for Human Ovarian Cancer

E2Fs are a family of pivotal transcription factors. Accumulative evidence indicates that aberrant expression or activation of E2Fs is a common phenomenon in malignances, and significant associations have been noted between E2Fs and tumorigenesis or progression in a wide range of cancers. However, the expression patterns and exact roles of each E2F contributing to tumorigenesis and progression of ovarian cancer (OC) have not yet been elucidated. In this study, we investigated the distinct expression and prognostic value of E2Fs in patients with OC by analyzing a series of databases, including ONCOMINE, GEPIA, cBioPortal, Metascape, and Kaplan–Meier plotter. The mRNA expression levels of E2F1/3/5/8 were found to be significantly upregulated in patients with OC and were obviously associated with tumor stage for OC. Aberrant expression of E2F2/5/7/8 was found to be associated with the clinical outcomes of patients with OC. These results suggest that E2F2/5/8 might serve as potential prognostic biomarkers and targets for OC. However, future studies are required to validate our findings and promote the clinical utility of E2Fs in OC.

Construction and investigation of lncRNA-associated ceRNA regulatory network in papillary thyroid cancer

Increasing evidence has experimentally proved the competitive endogenous RNA (ceRNA) hypothesis that long non-coding RNA (lncRNA) can affect the expression of RNA targets by competitively combining microRNA (miRNA) via miRNA response elements. However, an extensive ceRNA network of thyroid carcinoma in a large cohort has not been evaluated. We analyzed the RNAseq and miRNAseq data of 348 cases of primary papillary thyroid cancer (PTC) patients with clinical information downloaded from The Cancer Genome Atlas (TCGA) project to search for potential biomarkers or therapeutic targets. A computational approach was applied to build an lncRNA-miRNA-mRNA regulatory network of PTC. In total, 780 lncRNAs were detected as collectively dysregulated lncRNAs in all 3 PTC variants compared with normal tissues (fold change >2 and false discovery rate <0.05). The interactions among 45 lncRNAs, 13 miRNAs and 86 mRNAs constituted a ceRNA network of PTC. Nine out of the 45 aberrantly expressed lncRNAs were related to the clinical features of PTC patients. However, the expression levels of 3 lncRNAs (LINC00284, RBMS3-AS1 and ZFX-AS1) were identified to be tightly correlated with the patients overall survival (log-rank, P<0.05). The present study identified a list of specific lncRNAs associated with PTC progression and prognosis. This complex ceRNA interaction network in PTC may provide guidance for better understanding the molecular mechanisms underlying PTC.

NFYB-induced high expression of E2F1 contributes to oxaliplatin resistance in colorectal cancer via the enhancement of CHK1 signaling

As a third-generation platinum drug, oxaliplatin has been widely applied in colorectal cancer (CRC); however, acquired resistance to oxaliplatin has become a major obstacle. In the present study, we found that the nuclear transcription factor Y subunit beta (NFYB) and E2F transcription factor 1 (E2F1) expression levels were significantly higher in oxaliplatin-resistant DLD1 and RKO CRC (OR-CRC) cells than in non-resistant cells. Additionally, highly expressed NFYB transactivated the E2F1 gene, which is important to maintain oxaliplatin resistance in OR-CRC cells. And Sirt1-dependent deacetylation suppresses the proapoptotic activity of E2F1 in OR-CRC cells. Through profiling the transcriptome of OR-CRC cells following E2F1 knockdown, CHK1 was identified as a target of E2F1. Deprivation of CHK1 sensitized OR-CRC cells to oxaliplatin. In vitro and in vivo phenotype experiments confirmed that an intact NFYB-E2F1-CHK1 axis was required to suppress oxaliplatin-induced apoptosis and maintain the tumorigenicity in OR-CRC cells. Knockdown of E2F1 in OR-CRC cells also decreased the expression of Pol κ, which was essential for CHK1 activation. Consistently, a high level of NFYB, E2F1, or CHK1 predicted poor survival in CRC patients, especially with oxaliplatin treatment. Collectively, the NFYB-E2F1 pathway displays a crucial role in the chemoresistance of OR-CRC by inducing the expression and activation of CHK1, providing a possible therapeutic target for oxaliplatin resistance in CRC.

microRNA‑372 inhibits proliferation and induces apoptosis in human breast cancer cells by directly targeting E2F1

Breast cancer is the most prevalent cancer and the leading cause of cancer-associated mortalities among women worldwide today. Accumulating evidence suggested that miR-372 may serve important roles in the initiation and development of various human cancers. However, the role of miR-372 in breast cancer remains unknown. The present study demonstrated that the expression level of miR-372 in human breast cancer tissues and cell lines is significantly reduced compared with normal breast tissues cell lines. Furthermore, results of functional assays indicated that miR-372 inhibits cell proliferation and induces apoptosis in the MCF-7 human breast cancer cell line. E2F1 was identified as a direct functional target of miR-372 in breast cancer. In conclusion, the findings revealed that miR-372 may have the potential to act as a novel molecule for the diagnosis and therapy of patients with breast cancer.

E2F-1 targets miR-519d to regulate the expression of the ras homolog gene family member C

E2F1 (E2F transcription factor 1) can act as a tumor suppressor or oncogene. We report the molecular mechanism of E2F1 in ovarian carcinoma tumorigenesis and progression. E2F1 expression levels in ovarian carcinoma tissue were examined by immunohistochemistry. After E2F1 plasmid transfection and E2F1-microRNA-519d (miR-519d)/si-RhoC (Ras homolog gene family member C) co-transfection, ovarian cancer cell phenotypes and the related molecules were examined in vitro and in vivo. E2F1 was overexpressed in type I and type II ovarian carcinoma as compared to normal ovary tissues and normal fallopian tube tissues, respectively. E2F1 overexpression promoted cell proliferation, G1–S progression, survival, migration, and invasion in vitro; miR-519d or siRhoC co-transfection reversed E2F1 oncogenic effects. E2F1 overexpression promoted tumor growth in vivo; miR-519d overexpression inhibited it. E2F1 overexpression increased RhoC, Bcl-2, cyclin D1, survivin, MMP2 (matrix metalloproteinase 2), MMP9, STAT3 (signal transducer and activator of transcription 3), and HuR (ELAV-like RNA-binding protein 1) expression; miR-519d overexpression decreased their expression. E2F1 downregulated miR-519d directly and miR-519d downregulated RhoC directly. Conversely, miR-519d directly downregulated E2F1, There is a direct repressive regulatory loop between E2F1 and miR-519d. We provide evidence that E2F1/miR-519d/RhoC is a promising signaling pathway for diagnosing and treating ovarian carcinoma.

Effects of cancer-testis antigen, TFDP3, on cell cycle regulation and its mechanism in L-02 and HepG2 cell lines in vitro

TFDP3, also be known as HCA661, was one of the cancer-testis antigens, which only expressed in human tissues. The recent researches about TFDP3 mostly focused on its ability to control the drug resistance and apoptosis of tumor cells. However, the role of TFDP3 in the progress of the cell cycle is rarely involved. In this study, we examined the expression of TFDP3 in human liver tissues firstly. After that, we detect the expression of TFDP3 at the RNA level and protein level in L-02 cell line and HepG2 cell line, and the location of TFDP3 was defined by immunofluorescence technique. Furthermore, we synchronized the cells to G1 phase, S phase and G2 phase, and arrested cell mitosis. The localization of TFDP3 and co-localization with E2F1 molecules in different phases of hepatocyte lines. Finally, TFDP3 gene knockout was performed on L-02 and HepG2 cell lines, and detected the new cell cycles by flow cytometry. The result showed that the expression of TFDP3 molecule is negative in normal liver tissue, but positive in immortalized human hepatocyte cell line, and the expression level is lower than in hepatocellular carcinoma cell line. The expression level of TFDP3 was in the dynamic change of L-02 and HepG2 cell lines, and was related to the phase transition. TFDP3 can bind to E2F1 molecule to form E2F/TFDP3 complex; and the localizations of TFDP3 and E2F1 molecules and the co-localization were different in different phases of cell cycle in the nucleus and cytoplasm, which indicated that the E2F/TFDP3 complex involved in the process of regulating the cell cycle. By knocking down the TFDP3 expression level in L-02 and HepG2 cell lines, the cell cycle would be arrested in S phase, which confirmed that TFDP3 can be a potential target for tumor therapy.

Long noncoding RNA CRNDE functions as a competing endogenous RNA to promote metastasis and oxaliplatin resistance by sponging miR-136 in colorectal cancer

Colorectal neoplasia differentially expressed (CRNDE) is a novel gene recognized as a long noncoding RNA (lncRNA) that is highly elevated in colorectal cancer and many other solid tumors but its functions on metastasis and oxaliplatin (OXA) resistance are unknown. In our study, we confirmed the upregulation of CRNDE in both primary specimens from colorectal cancer patients and colorectal cancer cell lines. Knockdown of CRNDE expression inhibited the migration and invasion potency of colorectal cancer cells with no effect on cell apoptosis. Overexpression of CRNDE promoted the migration and invasion potency of colorectal cancer cells. Furthermore, we found that CRNDE conferred chemoresistance in colorectal cancer cells. Knockdown of CRNDE with OXA treatment decreased cell viability and promoted DNA damage and cell apoptosis, while the overexpression of CRNDE with OXA treatment reduced DNA damage and cell apoptosis. Further in-depth mechanistic studies revealed that CRNDE functioned as a competing endogenous RNA for miR-136, led to the de-repression of its endogenous target, E2F transcription factor 1 (E2F1). Overall, our findings demonstrate that CRNDE functions as a competing endogenous RNA to promote metastasis and OXA resistance by sponging miR-136 in colorectal cancer.