E2F1 promotes angiogenesis through the VEGF-C/VEGFR-3 axis in a feedback loop for cooperative induction of PDGF-B

Molecular targets and therapeutic strategies for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is known for its heterogeneous complexity and is often difficult to treat. TNBC lacks the expression of major hormonal receptors like estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2 and is further subdivided into androgen receptor (AR) positive and AR negative. In contrast, AR negative is also known as quadruple-negative breast cancer (QNBC). Compared to AR-positive TNBC, QNBC has a great scarcity of prognostic biomarkers and therapeutic targets. QNBC shows excessive cellular growth and proliferation of tumor cells due to increased expression of growth factors like EGF and various surface proteins. This study briefly reviews the limited data available as protein biomarkers that can be used as molecular targets in treating TNBC as well as QNBC. Targeted therapy and immune checkpoint inhibitors have recently changed cancer treatment. Many studies in medicinal chemistry continue to focus on the synthesis of novel compounds to discover new antiproliferative medicines capable of treating TNBC despite the abundance of treatments currently on the market. Drug repurposing is one of the therapeutic methods for TNBC that has been examined. Moreover, some additional micronutrients, nutraceuticals, and functional foods may be able to lower cancer risk or slow the spread of malignant diseases that have already been diagnosed with cancer. Finally, nanomedicines, or applications of nanotechnology in medicine, introduce nanoparticles with variable chemistry and architecture for the treatment of cancer. This review emphasizes the most recent research on nutraceuticals, medication repositioning, and novel therapeutic strategies for the treatment of TNBC.

E2F Transcription Factor 1 Activates FKBP Prolyl Isomerase 4 to Promote Angiogenesis in Cervical Squamous Cell Carcinoma Via the PI3K/AKT Signaling Pathway

Angiogenesis, namely the formation of blood vessels, is crucial for tumor growth, metastasis and development. E2F transcription factor 1 (E2F1) has been linked to tumorigenesis in several human cancers. This work examines the role of E2F1 and its downstream targets in angiogenesis in cervical squamous cell carcinoma (CSCC). E2F1 was predicted as a candidate oncogene in CSCC using a GSE63514 dataset. Increased E2F1 expression was detected in CSCC tumor samples and cell lines by RT-qPCR, immunohistochemistry, and western blot assays. E2F1 downregulation reduced the angiogenesis activity of HUVECs and the invasiveness of CSCC cells. In vivo, E2F1 knockdown also reduced the xenograft tumor growth and promoted tumor necrosis in mice. FKBP prolyl isomerase 4 (FKBP4) was identified as a target of E2F1. E2F1 bound to FKBP4 promoter for transcriptional activation. Further upregulation of FKBP4 blocked the tumor-suppressive role of E2F1 silencing. FKBP4 was enriched in the PI3K/AKT signaling. In cells and xenograft tumors, the E2F1/FKBP4 axis promoted PI3K and AKT phosphorylation. Activation of the PI3K/AKT signaling restored the angiogenesis activity in cells blocked by E2F1 silencing. In summary, this work demonstrates that E2F1 promotes FKBP4 transcription to activate the PI3K/AKT pathway, which augments the angiogenesis and invasiveness of CSCC.

Engineered Sandwich-Structured Composite Wound Dressings with Unidirectional Drainage and Anti-Adhesion Supporting Accelerated Wound Healing

Proper management of exudate is of great clinical value for reducing wound infection and promoting wound healing, thus various dressings have been studied to address this widespread medical challenge. Herein, a novel sandwich-structured composite wound dressing (SCWD), integrating of a superlyophobic (SLO) polydimethylsiloxane (PDMS) layer, a superlyophilic gauze layer, and a lyophobic PDMS layer is presented, with particular unidirectional droplet drainage and stable anti-adhesion capabilities, which realizes effective management of wound exudate and provides a favorable environment for wound healing. Thanks to the stable SLO property on the PDMS surface with hierarchical micro/nanostructures, the continuously accumulated wound exudate at the interface between dressing and wound surface is gradually deformed, eventually passing through SLO PDMS layer through milli-scale channels and being absorbed by gauze layer. Experimental results show that the application of SCWD can significantly reduce the occurrence of wound infection, avoid the tearing of wound tissues when replacing dressings, and accelerate wound healing by ≈20%. The combination of SCWD and lyophilized powders of stem cells supernatant (LPSCS) is verified to better accelerate the healing process. The proposed method offers great potential in clinical applications, particularly for acute trauma wound treatments.

An Insight into the Role of E2F1 in Breast Cancer Progression, Drug Resistance, and Metastasis

AIMS

This study aimed to investigate the role of E2F1 in breast cancer biology.

BACKGROUND

Expression of E2F1, a transcription factor of many oncogenes and tumor suppressor genes, is lowered in several malignancies, including breast carcinoma.

OBJECTIVES

In the present study, we analyzed the status of E2F1 expression in association with diverse attributes of breast malignancy and its impact on cancer progression.

METHODS

For this purpose, we used various freely available online applications for gene enrichment, expression, and methylation analysis to extract mutation-based E2F1 map, to measure E2F1 drug sensitivity, and to determine E2F1 association with DNA damage response proteins.

RESULTS

Results revealed tissue-specific regulatory behavior of E2F1. Moreover, the key role of E2F1 in the promotion of metastasis, stem cell-mediated carcinogenesis, estrogen-mediated cell proliferation, and cellular defense system, has therefore highlighted it as a metaplastic marker and hot member of key resistome pathways.

CONCLUSION

The information thus generated can be employed for future implications in devising rational therapeutic strategies. Moreover, this study has provided a more detailed insight into the diagnostic and prognostic potential of E2F1.

Drug Repurposing at the Interface of Melanoma Immunotherapy and Autoimmune Disease

Cancer cells have a remarkable ability to evade recognition and destruction by the immune system. At the same time, cancer has been associated with chronic inflammation, while certain autoimmune diseases predispose to the development of neoplasia. Although cancer immunotherapy has revolutionized antitumor treatment, immune-related toxicities and adverse events detract from the clinical utility of even the most advanced drugs, especially in patients with both, metastatic cancer and pre-existing autoimmune diseases. Here, the combination of multi-omics, data-driven computational approaches with the application of network concepts enables in-depth analyses of the dynamic links between cancer, autoimmune diseases, and drugs. In this review, we focus on molecular and epigenetic metastasis-related processes within cancer cells and the immune microenvironment. With melanoma as a model, we uncover vulnerabilities for drug development to control cancer progression and immune responses. Thereby, drug repurposing allows taking advantage of existing safety profiles and established pharmacokinetic properties of approved agents. These procedures promise faster access and optimal management for cancer treatment. Together, these approaches provide new disease-based and data-driven opportunities for the prediction and application of targeted and clinically used drugs at the interface of immune-mediated diseases and cancer towards next-generation immunotherapies.

Melanoma 2.0. Skin cancer as a paradigm for emerging diagnostic technologies, computational modelling and artificial intelligence

We live in an unprecedented time in oncology. We have accumulated samples and cases in cohorts larger and more complex than ever before. New technologies are available for quantifying solid or liquid samples at the molecular level. At the same time, we are now equipped with the computational power necessary to handle this enormous amount of quantitative data. Computational models are widely used helping us to substantiate and interpret data. Under the label of systems and precision medicine, we are putting all these developments together to improve and personalize the therapy of cancer. In this review, we use melanoma as a paradigm to present the successful application of these technologies but also to discuss possible future developments in patient care linked to them. Melanoma is a paradigmatic case for disruptive improvements in therapies, with a considerable number of metastatic melanoma patients benefiting from novel therapies. Nevertheless, a large proportion of patients does not respond to therapy or suffers from adverse events. Melanoma is an ideal case study to deploy advanced technologies not only due to the medical need but also to some intrinsic features of melanoma as a disease and the skin as an organ. From the perspective of data acquisition, the skin is the ideal organ due to its accessibility and suitability for many kinds of advanced imaging techniques. We put special emphasis on the necessity of computational strategies to integrate multiple sources of quantitative data describing the tumour at different scales and levels.

KAT2A/E2F1 Promotes Cell Proliferation and Migration via Upregulating the Expression of UBE2C in Pan-Cancer

Various studies have shown that lysine acetyltransferase 2A (KAT2A), E2F transcription factor 1 (E2F1), and ubiquitin conjugating enzyme E2 C (UBE2C) genes regulated the proliferation and migration of tumor cells through regulating the cell cycle. However, there is a lack of in-depth and systematic research on their mechanisms of action. This study analyzed The Cancer Genome Atlas (TCGA) to screen potential candidate genes and the regulation network of KAT2A and E2F1 complex in pan-cancer. Quantitative real-time PCR (qRT-PCR) and Western blotting (WB), cell phenotype detection, immunofluorescence co-localization, chromatin immunoprecipitation assay (ChIP), and RNA-Seq techniques were used to explore the functional of a candidate gene, UBE2C. We found that the expression of these three genes was significantly higher in more than 10 tumor types compared to normal tissue. Moreover, UBE2C was mainly expressed in tumor cells, which highlighted the impacts of UBE2C as a specific therapeutic strategy. Moreover, KAT2A and E2F1 could promote cell proliferation and the migration of cancer cells by enhancing the expression of UBE2C. Mechanically, KAT2A was found to cooperate with E2F1 and be recruited by E2F1 to the UBE2C promoter for elevating the expression of UBE2C by increasing the acetylation level of H3K9.

Virtual ChIP-seq: predicting transcription factor binding by learning from the transcriptome

Existing methods for computational prediction of transcription factor (TF) binding sites evaluate genomic regions with similarity to known TF sequence preferences. Most TF binding sites, however, do not resemble known TF sequence motifs, and many TFs are not sequence-specific. We developed Virtual ChIP-seq, which predicts binding of individual TFs in new cell types, integrating learned associations with gene expression and binding, TF binding sites from other cell types, and chromatin accessibility data in the new cell type. This approach outperforms methods that predict TF binding solely based on sequence preference, predicting binding for 36 TFs (MCC>0.3).

MiR-423-5p activated by E2F1 promotes neovascularization in diabetic retinopathy by targeting HIPK2

BACKGROUND

Diabetic retinopathy (DR) is a diabetic complication and the primary cause of blindness in the world. However, the treatments of DR are challenging given its complicated pathogenesis. Here, we investigated the molecular mechanisms of DR by focusing on the function of E2F1/miR-423-5p/HIPK2/HIF1α/VEGF axis.

METHODS

Cultured retinal endothelial cells (hRMECs, hRECs) were treated with 25 mM glucose to mimic the high glucose-induced DR in vitro. Streptozotocin (STZ) was injected into mice to induce DR in mice. qRT-PCR, western blotting, immunohistochemistry, and ELISA were employed to measure levels of E2F1, miR-423-5p, HIPK2, HIF1α, and VEGF. H&E staining was utilized to examine retinal neovascularization. CCK-8 assay, transwell assay, and vascular tube formation assay were used to assess the cell viability, migration, and angiogenesis. Dual luciferase assay was performed to validate interactions between E2F1 and miR-423-5p, miR-423-5p and HIPK2.

RESULTS

HG treatment increased the cell viability, migration, and angiogenesis accompanied by upregulation of E2F1, miR-423-5p, HIF1α, and VEGF levels, but reduction in HIPK2 expression. Knockdown of E2F1 or miR-423-5p suppressed the HG-induced increases in cell viability, migration, and angiogenesis. E2F1 transcriptionally activated miR-423-5p expression and miR-423-5p mimics blocked the effects of E2F1 knockdown on angiogenesis. Moreover, miR-423-5p directly targeted HIPK2 to disinhibit HIF1α/VEGF signaling. Knockdown of HIPK2 reversed the effects of miR-423-5p inhibitor on cell viability, migration, and angiogenesis. Knockdown of E2F1 suppressed neovascularization during DR in vivo.

CONCLUSIONS

E2F1 activates miR-423-5p transcription during DR to promote angiogenesis via suppressing HIPK2 expression to disinhibit HIF1α/VEGF signaling. Strategies targeting E2F1/miR-423-5p/HIPK2 axis could be potentially used for DR treatment.

Experimental Models to Study Skin Wound Healing with a Focus on Angiogenesis

A large number of models are now available for the investigation of skin wound healing. These can be used to study the processes that take place in a phase-specific manner under both physiological and pathological conditions. Most models focus on wound closure, which is a crucial parameter for wound healing. However, vascular supply plays an equally important role and corresponding models for selective or parallel investigation of microcirculation regeneration and angiogenesis are also described. In this review article, we therefore focus on the different levels of investigation of skin wound healing (in vivo to in virtuo) and the investigation of angiogenesis and its parameters.

Identification of Prognostic miRNAs Associated With Immune Cell Tumor Infiltration Predictive of Clinical Outcomes in Patients With Non-Small Cell Lung Cancer

Background

A detailed means of prognostic stratification in patients with non-small cell lung cancer (NSCLC) is urgently needed to support individualized treatment plans. Recently, microRNAs (miRNAs) have been used as biomarkers due to their previously reported prognostic roles in cancer. This study aimed to construct an immune-related miRNA signature that effectively predicts NSCLC patient prognosis.

Methods

The miRNAs and mRNA expression and mutation data of NSCLC was obtained from The Cancer Genome Atlas (TCGA). Immune-associated miRNAs were identified using immune scores calculated by the ESTIMATE algorithm. LASSO-penalized multivariate survival models were using for development of a tumor immune-related miRNA signature (TIM-Sig), which was evaluated in several public cohorts from the Gene Expression Omnibus (GEO) and the CellMiner database. The miRTarBase was used for constructing the miRNA-target interactions.

Results

The TIM-Sig, including 10 immune-related miRNAs, was constructed and successfully predicted overall survival (OS) in the validation cohorts. TIM-Sig score negatively correlated with CD8+ T cell infiltration, IFN-γ expression, CYT activity, and tumor mutation burden. The correlation between TIM-Sig score and genomic mutation and cancer chemotherapeutics was also evaluated. A miRNA-target network of 10 miRNAs in TIM-Sig was constructed. Further analysis revealed that these target genes showed prognostic value in both lung squamous cell carcinoma and adenocarcinoma.

Conclusions

We concluded that the immune-related miRNAs demonstrated a potential value in clinical prognosis.

E2F1-mediated repression of WNT5A expression promotes brain metastasis dependent on the ERK1/2 pathway in EGFR-mutant non-small cell lung cancer

Brain metastasis (BM) is associated with poor prognosis in patients with advanced non-small cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR) mutation reportedly enhances the development of BM. However, the exact mechanism of how EGFR-mutant NSCLC contributes to BM remains unknown. Herein, we found the protein WNT5A, was significantly downregulated in BM tissues and EGFR-mutant samples. In addition, the overexpression of WNT5A inhibited the growth, migration, and invasion of EGFR-mutant cells in vitro and retarded tumor growth and metastasis in vivo compared with the EGFR wide-type cells. We demonstrated a molecular mechanism whereby WNT5A be negatively regulated by transcription factor E2F1, and ERK1/2 inhibitor (U0126) suppressed E2F1's regulation of WNT5A expression in EGFR-mutant cells. Furthermore, WNT5A inhibited β-catenin activity and the transcriptional levels of its downstream genes in cancer progression. Our research revealed the role of WNT5A in NSCLC BM with EGFR mutation, and proved that E2F1-mediated repression of WNT5A was dependent on the ERK1/2 pathway, supporting the notion that targeting the ERK1/2-E2F1-WNT5A pathway could be an effective strategy for treating BM in EGFR-mutant NSCLC.

DNMT3A inhibits E2F1-induced arterial marker expression and impairs angiogenesis in human umbilical artery endothelial cells

Arterial marker genes EphrinB2 and HEY2 are essential for cardiovascular development and postnatal neovascularization. Our previous study confirmed that E2F1 could activate the transcription of EphrinB2 and HEY2 in human mesenchymal stem cells; however, the detailed mechanism has not been resolved yet. In this study, we focused on the interaction between E2F1 and DNMT3A, a de novo DNA methyltransferase, on regulating the expression of EphrinB2 and HEY2, and explored the potential mechanisms. Gain- and loss-of-function experiments implicated the positive effect of E2F1 on the expression of EphrinB2 and HEY2 and tube formation in human umbilical artery endothelial cells. Accumulation of DNMT3A decreased the levels of EphrinB2 and HEY2, and impaired tube formation induced by E2F1, while inhibiting DNMT3A by RNA interference augmented their expression and angiogenesis in E2F1-trasfected cells. We then asked whether the low expressions of EphrinB2 and HEY2 induced by DNMT3A are related to the methylation status of their promoters. Surprisingly, the methylation status of the CpG islands in the promoter region was not significantly affected by overexpression of exogenous DNMT3A. Furthermore, the interaction between E2F1 and DNMT3A was confirmed by co-immunoprecipitation. DNMT3A could inhibit the transcription of EphrinB2 and HEY2 promoters by affecting the binding of E2F1 to its recognition sequences as revealed by luciferase reporter assay and chromatin immunoprecipitation. These results identified a novel mechanism underlying the cooperation of DNMT3A with E2F1 on regulating target gene expression, and revealed their roles in the angiogenic process.

Quadruple-negative breast cancer: novel implications for a new disease

Based on the androgen receptor (AR) expression, triple-negative breast cancer (TNBC) can be subdivided into AR-positive TNBC and AR-negative TNBC, also known as quadruple-negative breast cancer (QNBC). QNBC characterization and treatment is fraught with many challenges. In QNBC, there is a greater paucity of prognostic biomarkers and therapeutic targets than AR-positive TNBC. Although the prognostic role of AR in TNBC remains controversial, many studies revealed that a lack of AR expression confers a more aggressive disease course. Literature characterizing QNBC tumor biology and uncovering novel biomarkers for improved management of the disease remains scarce. In this comprehensive review, we summarize the current QNBC landscape and propose avenues for future research, suggesting potential biomarkers and therapeutic strategies that warrant investigation.

Realizing Cancer Precision Medicine by Integrating Systems Biology and Nanomaterial Engineering

Many clinical trials for cancer precision medicine have yielded unsatisfactory results due to challenges such as drug resistance and low efficacy. Drug resistance is often caused by the complex compensatory regulation within the biomolecular network in a cancer cell. Recently, systems biological studies have modeled and simulated such complex networks to unravel the hidden mechanisms of drug resistance and identify promising new drug targets or combinatorial or sequential treatments for overcoming resistance to anticancer drugs. However, many of the identified targets or treatments present major difficulties for drug development and clinical application. Nanocarriers represent a path forward for developing therapies with these "undruggable" targets or those that require precise combinatorial or sequential application, for which conventional drug delivery mechanisms are unsuitable. Conversely, a challenge in nanomedicine has been low efficacy due to heterogeneity of cancers in patients. This problem can also be resolved through systems biological approaches by identifying personalized targets for individual patients or promoting the drug responses. Therefore, integration of systems biology and nanomaterial engineering will enable the clinical application of cancer precision medicine to overcome both drug resistance of conventional treatments and low efficacy of nanomedicine due to patient heterogeneity.

CD146, from a melanoma cell adhesion molecule to a signaling receptor

CD146 was originally identified as a melanoma cell adhesion molecule (MCAM) and highly expressed in many tumors and endothelial cells. However, the evidence that CD146 acts as an adhesion molecule to mediate a homophilic adhesion through the direct interactions between CD146 and itself is still lacking. Recent evidence revealed that CD146 is not merely an adhesion molecule, but also a cellular surface receptor of miscellaneous ligands, including some growth factors and extracellular matrixes. Through the bidirectional interactions with its ligands, CD146 is actively involved in numerous physiological and pathological processes of cells. Overexpression of CD146 can be observed in most of malignancies and is implicated in nearly every step of the development and progression of cancers, especially vascular and lymphatic metastasis. Thus, immunotherapy against CD146 would provide a promising strategy to inhibit metastasis, which accounts for the majority of cancer-associated deaths. Therefore, to deepen the understanding of CD146, we review the reports describing the newly identified ligands of CD146 and discuss the implications of these findings in establishing novel strategies for cancer therapy.

LncRNA-SLC16A1-AS1 induces metabolic reprogramming during Bladder Cancer progression as target and co-activator of E2F1

Long non-coding RNAs (lncRNAs) have emerged as integral components of E2F1-regulated gene regulatory networks (GRNs), but their implication in advanced or treatment-refractory malignancy is unknown. Methods: We combined high-throughput transcriptomic approaches with bioinformatics and structure modeling to search for lncRNAs that participate in E2F1-activated prometastatic GRNs and their phenotypic targets in the highly-relevant case of E2F1-driven aggressive bladder cancer (BC). RNA immunoprecipitation was performed to verify RNA-protein interactions. Functional analyses including qRT-PCR, immunoblotting, luciferase assays and measurement of extracellular fluxes were conducted to validate expression and target gene regulation. Results: We identified E2F1-responsive lncRNA-SLC16A1-AS1 and its associated neighboring protein-coding gene, SLC16A1/MCT1, which both promote cancer invasiveness. Mechanistically, upon E2F1-mediated co-transactivation of the gene pair, SLC16A1-AS1 associates with E2F1 in a structure-dependent manner and forms an RNA-protein complex that enhances SLC16A1/MCT1 expression through binding to a composite SLC16A1-AS1:E2F1-responsive promoter element. Moreover, SLC16A1-AS1 increases aerobic glycolysis and mitochondrial respiration and fuels ATP production by fatty acid β-oxidation. These metabolic changes are accompanied by alterations in the expression of the SLC16A1-AS1:E2F1-responsive gene PPARA, a key mediator of fatty acid β-oxidation. Conclusions: Our results unveil a new gene regulatory program by which E2F1-induced lncRNA-SLC16A1-AS1 forms a complex with its transcription factor that promotes cancer metabolic reprogramming towards the acquisition of a hybrid oxidative phosphorylation/glycolysis cell phenotype favoring BC invasiveness.

Cancer-testis specific gene OIP5: a downstream gene of E2F1 that promotes tumorigenesis and metastasis in glioblastoma by stabilizing E2F1 signaling

Background

The cancer-testis specific gene Opa interacting protein 5 (OIP5) is reactivated in many human cancers, but its functions in glioblastoma remain unclear. Here, we assessed the significance of OIP5 in the tumorigenesis and metastasis of glioblastoma for the first time.

Methods

An immunohistochemistry assay was performed to detect OIP5 expression changes in glioblastoma patients. Overall survival analysis was performed to evaluate the prognostic significance of OIP5. Growth curve, colony formation, and transwell assays were used to analyze cell proliferation and metastasis. Tumorigenicity potential was investigated in orthotopic tumor models, and immunoprecipitation, chromatin immunoprecipitation, and luciferase assays were employed to explore the mechanisms underlying the activation of OIP5 expression by E2F transcription factor 1 (E2F1) to stabilize and maintain E2F1 signaling.

Results

OIP5 was found to be upregulated in glioblastoma patients and to impair patient survival, and the increased expression of OIP5 was positively correlated with tumor stage. Compared with short hairpin green fluorescent protein cells, cells in which OIP5 was knocked down exhibited significantly reduced proliferation, metastasis, colony formation, and tumorigenicity abilities, whereas OIP5 recovery enhanced these abilities. OIP5 was highly correlated with cell cycle progression but had no obvious effects on apoptosis. Notably, we demonstrated a feedback loop in which E2F1 activates the expression of OIP5 to stabilize and maintain E2F1 signaling and promote the E2F1-regulated gene expression that is required for aggressive tumor biology.

Conclusions

Collectively, our findings demonstrate that OIP5 promotes glioblastoma progression and metastasis, suggesting that OIP5 is a potential target for anticancer therapy.

Therapeutic Targeting of MZF1-AS1/PARP1/E2F1 Axis Inhibits Proline Synthesis and Neuroblastoma Progression

Proline synthesis plays an important role in the metabolic reprogramming that contributes to tumor progression. However, the mechanisms regulating expression of proline synthetic genes in neuroblastoma (NB) remain elusive. Herein, through integrative screening of a public dataset and amino acid profiling analysis, myeloid zinc finger 1 (MZF1) and MZF1 antisense RNA 1 (MZF1-AS1) are identified as transcriptional regulators of proline synthesis and NB progression. Mechanistically, transcription factor MZF1 promotes the expression of aldehyde dehydrogenase 18 family member A1 and pyrroline-5-carboxylate reductase 1, while proline facilitates the aggressiveness of NB cells. In addition, MZF1-AS1 binds poly(ADP-ribose) polymerase 1 (PARP1) to facilitate its interaction with E2F transcription factor 1 (E2F1), resulting in transactivation of E2F1 and upregulation of MZF1 and other oncogenic genes associated with tumor progression. Administration of a small peptide blocking MZF1-AS1-PARP1 interaction or lentivirus-mediated short hairpin RNA targeting MZF1-AS1 suppresses the proline synthesis, tumorigenesis, and aggressiveness of NB cells. In clinical NB cases, high expression of MZF1-AS1, PARP1, E2F1, or MZF1 is associated with poor survival of patients. These results indicate that therapeutic targeting of MZF1-AS1/PARP1/E2F1 axis inhibits proline synthesis and NB progression.

Site-specific amino acid substitution in dodecameric peptides determines the stability and unfolding of c-MYC quadruplex promoting apoptosis in cancer cells

c-MYC proto-oncogene harbours a transcription-inhibitory quadruplex-forming scaffold (Pu27) upstream P₁ promoter providing anti-neoplastic therapeutic target. Previous reports showed the binding profile of human Cathelicidin peptide (LL37) and telomeric G-quadruplex. Here, we truncated the quadruplex-binding domain of LL37 to prepare a small library of peptides through site-specific amino acid substitution. We investigated the intracellular selectivity of peptides for Pu27 over other oncogenic quadruplexes and their role in c-MYC promoter repression by dual-luciferase assays. We analysed their thermodynamics of binding reactions with c-MYC quadruplex isomers (Pu27, Myc22, Pu19) by Isothermal Titration Calorimetry. We discussed how amino acid substitutions and peptide helicity enhanced/weakened their affinities for c-MYC quadruplexes and characterized specific non-covalent inter-residual interactions determining their selectivity. Solution NMR structure indicated that KR12C, the best peptide candidate, selectively stabilized the 5′-propeller loop of c-MYC quadruplex by arginine-driven electrostatic-interactions at the sugar-phosphate backbone while KR12A peptide destabilized the quadruplex inducing a single-stranded hairpin-like conformation. Chromatin immunoprecipitations envisaged that KR12C and KR12A depleted and enriched Sp1 and NM23-H2 (Nucleoside diphosphate kinase) occupancy at Pu27 respectively supporting their regulation in stabilizing and unfolding c-MYC quadruplex in MCF-7 cells. We deciphered that selective arresting of c-MYC transcription by KR12C triggered apoptotic-signalling pathway via VEGF-A-BCL-2 axis.

E2F1 Drives Breast Cancer Metastasis by Regulating the Target Gene FGF13 and Altering Cell Migration

In prior work we demonstrated that loss of E2F transcription factors inhibits metastasis. Here we address the mechanisms for this phenotype and identify the E2F regulated genes that coordinate tumor cell metastasis. Transcriptomic profiling of E2F1 knockout tumors identified a role for E2F1 as a master regulator of a suite of pro-metastatic genes, but also uncovered E2F1 target genes with an unknown role in pulmonary metastasis. High expression of one of these genes, Fgf13, is associated with early human breast cancer metastasis in a clinical dataset. Together these data led to the hypothesis that Fgf13 is critical for breast cancer metastasis, and that upregulation of Fgf13 may partially explain how E2F1 promotes breast cancer metastasis. To test this hypothesis we ablated Fgf13 via CRISPR. Deletion of Fgf13 in a MMTV-PyMT breast cancer cell line reduces colonization of the lungs in a tail vein injection. In addition, loss of Fgf13 reduced in vitro cell migration, suggesting that Fgf13 may be critical for tumor cells to escape the primary tumor and to colonize the distal sites. The significance of this work is twofold: we have both uncovered genomic features by which E2F1 regulates metastasis and we have identified new pro-metastatic functions for the E2F1 target gene Fgf13.

Prognostic Role of Chicken Ovalbumin Upstream Promoter Transcription Factor II in Isocitrate Dehydrogenase-Mutant Glioma with 1p19q Co-Deletion

BACKGROUND

Chicken ovalbumin upstream promoter transcription factor II is known to play a crucial role in the tumor microenvironment. However, the role of NR2F2 in gliomas is unknown.

METHODS

The genomic and clinical data of 530 cases of lower grade gliomas (LGGs) patients and 167 cases of glioblastoma (GBM) patients in The Cancer Genome Atlas (TCGA) were extracted for analysis. R2 and UCSC Xena browser were used for Kaplan-Meier survival in the GSE16011 dataset and TCGA dataset, respectively. GraphPad Prism 7 was used to compare the differences in NR2F2 expression between various groups and subtypes.

RESULTS

LGG patients with low NR2F2 expression had a significantly favorable outcome compared with those with high NR2F2 expression (p < 0.05). By matching histological subtypes and gene expression profiles of LGG patients, grade II glioma group showed lowest levels of NR2F2 expression compared with grade III gliomas and GBM. Patients diagnosed with astrocytoma have highest expression of NR2F2 but lowest OS (p < 0.05). In LGGs, NR2F2 expression was significantly downregulated in patient group with IDH mutation and 1p19q co-deletion (p < 0.05).

CONCLUSION

Our study suggests that NR2F2 can be used as a prognostic marker in LGG patients with IDH mutation and 1p19 co-deletion.

Drug Repositioning Inferred from E2F1-Coregulator Interactions Studies for the Prevention and Treatment of Metastatic Cancers

Metastasis management remains a long-standing challenge. High abundance of E2F1 triggers tumor progression by developing protein-protein interactions (PPI) with coregulators that enhance its potential to activate a network of prometastatic transcriptional targets.

Methods: To identify E2F1-coregulators, we integrated high-throughput Co-immunoprecipitation (IP)/mass spectometry, GST-pull-down assays, and structure modeling. Potential inhibitors of PPI discovered were found by bioinformatics-based pharmacophore modeling, and transcriptome profiling was conducted to screen for coregulated downstream targets. Expression and target gene regulation was validated using qRT-PCR, immunoblotting, chromatin IP, and luciferase assays. Finally, the impact of the E2F1-coregulator complex and its inhibiting drug on metastasis was investigated in vitro in different cancer entities and two mouse metastasis models.

Results: We unveiled that E2F1 forms coactivator complexes with metastasis-associated protein 1 (MTA1) which, in turn, is directly upregulated by E2F1. The E2F1:MTA1 complex potentiates hyaluronan synthase 2 (HAS2) expression, increases hyaluronan production and promotes cell motility. Disruption of this prometastatic E2F1:MTA1 interaction reduces hyaluronan synthesis and infiltration of tumor-associated macrophages in the tumor microenvironment, thereby suppressing metastasis. We further demonstrate that E2F1:MTA1 assembly is abrogated by small-molecule, FDA-approved drugs. Treatment of E2F1/MTA1-positive, highly aggressive, circulating melanoma cells and orthotopic pancreatic tumors with argatroban prevents metastasis and cancer relapses in vivo through perturbation of the E2F1:MTA1/HAS2 axis.

Conclusion: Our results propose argatroban as an innovative, E2F-coregulator-based, antimetastatic drug. Cancer patients with the infaust E2F1/MTA1/HAS2 signature will likely benefit from drug repositioning.

Modeling and antitumor studies of a modified L-penetratin peptide targeting E2F in lung cancer and prostate cancer

E2F1-3a overexpression due to amplification or to mutation or loss of the retinoblastoma gene, induces genes involved in DNA synthesis and leads to abnormal cellular proliferation, tumor growth, and invasion. Therefore, inhibiting the overexpression of one or more of these activating E2Fs is a recognized target in cancer therapeutics. In previous studies we identified by phage display, a novel 7-mer peptide (PEP) that bound tightly to an immobilized consensus E2F1 promoter sequence, and when conjugated to penetratin to increase its uptake into cells, was cytotoxic to several malignant cell lines and human prostate and small cell lung cancer xenografts. Based on molecular simulation studies that showed that the D-Arg penetratin peptide (D-Arg PEP) secondary structure is more stable than the L-Arg PEP, the L-Arg in the peptide was substituted with D-Arg. In vitro studies confirmed that it was more stable than the L- form and was more cytotoxic as compared to the L-Arg PEP when tested against the human castrate resistant cell line, DU145 and the human lung cancer H196 cell line. When encapsulated in PEGylated liposomes, the D-Arg-PEP potently inhibited growth of the DU145 xenograft in mice. Our findings validate D- Arg PEP, an inhibitor of E2F1and 3a transcription, as an improved second generation drug candidate for targeted molecular therapy of cancers with elevated levels of activated E2F(s).

The role of PDGF-B/PDGFR-BETA axis in the normal development and carcinogenesis of the breast

PDGFs/PDGFRs axis is documented as an important tumor-promoting agent and potential therapeutic target for several human carcinomas, including breast cancer. However, little is known about the role played by the PDGF family members in the normal development of the breast tissue, breast carcinogenesis and tumor-microenvironment dynamics Despite its potent pro-lymphangiogenic effects, PDGF-B/PDGFR-beta axis remains controversial and incompletely elucidated in the field of breast cancer, with emphasis to its differential implications in breast cancer molecular subtypes. Although some data are available concerning this aspect, little or no information is found regarding the role of the PDGF-B/PDGFR-beta axis in rare and aggressive types of breast cancers, such as triple negative breast cancers (TNBCs) and its associated subtypes This review attempted to gather as many data as possible concerning PDGFs family members in the normal breast tissue and in breast carcinogenesis with special focus on their role in diagnosis and therapeutic approach.

Emerging functional markers for cancer stem cell-based therapies: Understanding signaling networks for targeting metastasis

Metastasis is one of the most challenging issues in cancer patient management, and effective therapies to specifically target disease progression are missing, emphasizing the urgent need for developing novel anti-metastatic therapeutics. Cancer stem cells (CSCs) gained fast attention as a minor population of highly malignant cells within liquid and solid tumors that are responsible for tumor onset, self-renewal, resistance to radio- and chemotherapies, and evasion of immune surveillance accelerating recurrence and metastasis. Recent progress in the identification of their phenotypic and molecular characteristics and interactions with the tumor microenvironment provides great potential for the development of CSC-based targeted therapies and radical improvement in metastasis prevention and cancer patient prognosis. Here, we report on newly uncovered signaling mechanisms controlling CSC's aggressiveness and treatment resistance, and CSC-specific agents and molecular therapeutics, some of which are currently under investigation in clinical trials, gearing towards decisive functional CSC intrinsic or surface markers. One special research focus rests upon subverted regulatory pathways such as insulin-like growth factor 1 receptor signaling and its interactors in metastasis-initiating cell populations directly related to the gain of stem cell- and EMT-associated properties, as well as key components of the E2F transcription factor network regulating metastatic progression, microenvironmental changes, and chemoresistance. In addition, the study provides insight into systems biology tools to establish complex molecular relationships behind the emergence of aggressive phenotypes from high-throughput data that rely on network-based analysis and their use to investigate immune escape mechanisms or predict clinical outcome-relevant CSC receptor signaling signatures. We further propose that customized vector technologies could drastically enhance systemic drug delivery to target sites, and summarize recent progress and remaining challenges. This review integrates available knowledge on CSC biology, computational modeling approaches, molecular targeting strategies, and delivery techniques to envision future clinical therapies designed to conquer metastasis-initiating cells.

Co-expression of PDGF-B and VEGFR-3 strongly correlates with poor prognosis in hepatocellular carcinoma patients after hepatectomy

BACKGROUND

The ability to evaluate the prognosis of hepatocellular carcinoma (HCC) patients following hepatectomy with biological markers is of great importance.

METHODS

In this study, we collected samples from 90 patients with HCC after hepatectomy. Immunohistochemistry was used to detect the expression of PDGF-B and VEGFR-3 in these HCC samples.

RESULTS

According to the immunohistochemical results, PDGF-B and VEGFR-3 staining were significantly associated with clinical features. Additionally, a significant association between high PDGF-B and VEGFR-3 levels and shorter overall survival was noted, when PDGF-B and VEGFR-3 co-expression been analyzed.

CONCLUSION

These results suggest that the correlative expression level of PDGF-B and VEGFR-3 has strong value in the prognosis of HCC patients following hepatectomy.

Rb is required for retinal angiogenesis and lamination

Retinoblastoma tumor suppressor (Rb) promotes cell cycle exit, survival, differentiation, and tumor suppression in the retina. Here, we show it is also essential for vascularization and lamination. Despite minimal effects on Hif1a target expression, intraretinal vascular plexi did not form in the Rb ^-/- murine retina. Deleting adenovirus E2 promoter binding factor 3 (E2f3), which rescues starburst amacrine cell differentiation, or E2f2, had no effect, but deleting E2f1, which promotes neuronal cell cycle exit and survival, restored retinal vasculature. We specifically linked cell loss to the defect because removing Bax rescued rod and bipolar neurons and the vasculature, but not cell cycle exit. Despite rescuing Rb ^-/- neurons, Bax deletion exacerbated a delay in outer retina lamination, and exposed a requirement for Rb in inner retina lamination. The latter resembled Sem5 or FAT atypical cadherin 3 (Fat3) mutants, but expression of Sem5/Fat3 pathway components, or that of Neogenin, which perturbs migration in the Rb ^-/- cortex, was unchanged. Instead, lamination defects correlated with ectopic division, and were E2f1-dependent, implicating the cell cycle machinery. These in vivo studies expose new developmental roles for Rb, pinpoint aberrant E2f1 and Bax activity in neuronal death and vascular loss, and further implicate E2f1 in defective lamination. Links between Rb, angiogenesis and lamination have implications for the treatment of neovascularization, neurodegeneration and cancer.

Cancer-associated fibroblasts affect breast cancer cell gene expression, invasion and angiogenesis

PURPOSE

It has been reported that stromal cell features may affect the clinical outcome of breast cancer patients. Cancer associated fibroblasts (CAFs) represent one of the most abundant cell types within the breast cancer stroma. Here, we aimed to explore the influence of CAFs on breast cancer gene expression, as well as on invasion and angiogenesis.

METHODS

qRT-PCR was used to evaluate the expression of several cancer progression related genes (S100A4, TGFβ, FGF2, FGF7, PDGFA, PDGFB, VEGFA, IL-6, IL-8, uPA, MMP2, MMP9, MMP11 and TIMP1) in the human breast cancer-derived cell lines MCF-7 and MDA-MB-231, before and after co-culture with CAFs. Stromal mononuclear inflammatory cell (MIC) MMP11 expression was used to stratify primary tumors. In addition, we assessed the in vitro effects of CAFs on both MDA-MB-231 breast cancer cell invasion and endothelial cell (HUVEC) tube formation.

RESULTS

We found that the expression levels of most of the genes tested were significantly increased in both breast cancer-derived cell lines after co-culture with CAFs from either MMP11+ or MMP11- MIC tumors. IL-6 and IL-8 showed an increased expression in both cancer-derived cell lines after co-culture with CAFs from MMP11+ MIC tumors. We also found that the invasive and angiogenic capacities of, respectively, MDA-MB-231 and HUVEC cells were increased after co-culture with CAFs, especially those from MMP11+ MIC tumors.

CONCLUSIONS

Our data indicate that tumor-derived CAFs can induce up-regulation of genes involved in breast cancer progression. Our data additionally indicate that CAFs, especially those derived from MMP11+ MIC tumors, can promote breast cancer cell invasion and angiogenesis.

Transcription factor E2F1 promotes EMT by regulating ZEB2 in small cell lung cancer

BACKGROUND

Epithelial-mesenchymal transition (EMT) is an early event in tumour invasion and metastasis, and widespread and distant metastasis at early stages is the typical biological behaviour in small cell lung cancer (SCLC). Our previous reports showed that high expression of the transcription factor E2F1 was involved in the invasion and metastasis of SCLC, but the role of E2F1 in the process of EMT in SCLC is unknown.

METHODS

Immunohistochemistry was performed to evaluate the expressions of EMT related markers. Immunofluorescence was used to detect the expressions of cytoskeletal proteins and EMT related markers when E2F1 was silenced in SCLC cell lines. Adenovirus containing shRNA against E2F1 was used to knock down the E2F1 expression, and the dual luciferase reporter system was employed to clarify the regulatory relationship between E2F1 and ZEB2.

RESULTS

In this study, we observed the remodelling of cytoskeletal proteins when E2F1 was silenced in SCLC cell lines, indicating that E2F1 was involved in the EMT in SCLC. Depletion of E2F1 promoted the expression of epithelial markers (CDH1 and CTNNB1) and inhibited the expression of mesenchymal markers (VIM and CDH2) in SCLC cell lines, verifying that E2F1 promotes EMT occurrence. Next, the mechanism by which E2F1 promoted EMT was explored. Among the CDH1 related inhibitory transcriptional regulators ZEB1, ZEB2, SNAI1 and SNAI2, the expression of ZEB2 was the highest in SCLC tissue samples and was highly consistent with E2F1 expression. ChIP-seq data and dual luciferase reporter system analysis confirmed that E2F1 could regulate ZEB2 gene expression.

CONCLUSION

Our data supports that E2F1 promotes EMT by regulating ZEB2 gene expression in SCLC.

E2F1 silencing inhibits migration and invasion of osteosarcoma cells via regulating DDR1 expression

In the present study, knockdown of E2F1 impaired the migration and invasion of osteosarcoma cells. Further analysis showed that E2F1 knockdown decreased the expression of discoidin domain receptor 1 (DDR1) which plays a crucial role in many fundamental processes such as cell differentiation, adhesion, migration and invasion. Luciferase and ChIP assays confirmed that E2F1 silencing attenuated the expression of DDR1 through disrupting E2F1-mediated transcription of DDR1 in osteosarcoma cells. Similarly with the effect of E2F1 silencing, DDR1 knockdown weakened the migratory and invasive capabilities of osteosarcoma cells; while overexpression of DDR1 resulted in a significant increase of cell motility and invasiveness, even after knocking down E2F1. Interestingly, inactivation of E2F1/DDR1 pathway by shRNA weakened STAT3 signaling and subsequently suppressed the epithelial-mesenchymal transition (EMT) of osteosarcoma cells, as shown with decreased vimentin, MMP2, MMP9, and increased E-cadherin. Consistently, high expressions of E2F1 and DDR1 observed in osteosarcoma tissues were related to TNM stage and metastasis. In addition, high level of E2F1 or DDR1 was associated with poor prognosis in osteosarcoma patients. These results suggest that E2F1/DDR1/STAT3 pathway is critical for malignancy of osteosarcoma, which may provide a novel prognostic indicator or approach for osteosarcoma therapy.

Advances in cancer stem cell targeting: How to strike the evil at its root

Cancer progression to metastatic stages is still unmanageable and the promise of effective anti-metastatic therapy remains largely unmet, emphasizing the need to develop novel therapeutics. The special focus here is on cancer stem cells (CSC) as the seed of tumor initiation, epithelial-mesenchymal transition, chemoresistance and, as a consequence, drivers of metastatic dissemination. We report on targeted therapies gearing towards the CSC's internal and membrane-anchored markers using agents such as antibody derivatives, nucleic therapeutics, small molecules and genetic payloads. Another emphasis lies on novel proceedings envisaged to deliver current and prospective therapies to the target sites using newest viral and non-viral vector technologies. In this review, we summarize recent progress and remaining challenges in therapeutic strategies to combat CSC.

Unraveling a tumor type-specific regulatory core underlying E2F1-mediated epithelial-mesenchymal transition to predict receptor protein signatures

Cancer is a disease of subverted regulatory pathways. In this paper, we reconstruct the regulatory network around E2F, a family of transcription factors whose deregulation has been associated to cancer progression, chemoresistance, invasiveness, and metastasis. We integrate gene expression profiles of cancer cell lines from two E2F1-driven highly aggressive bladder and breast tumors, and use network analysis methods to identify the tumor type-specific core of the network. By combining logic-based network modeling, in vitro experimentation, and gene expression profiles from patient cohorts displaying tumor aggressiveness, we identify and experimentally validate distinctive, tumor type-specific signatures of receptor proteins associated to epithelial-mesenchymal transition in bladder and breast cancer. Our integrative network-based methodology, exemplified in the case of E2F1-induced aggressive tumors, has the potential to support the design of cohort- as well as tumor type-specific treatments and ultimately, to fight metastasis and therapy resistance.Deregulation of E2F family transcription factors is associated with cancer progression and metastasis. Here, the authors construct a map of the regulatory network around the E2F family, and using gene expression profiles, identify tumour type-specific regulatory cores and receptor expression signatures associated with epithelial-mesenchymal transition in bladder and breast cancer.

E2F1 Signalling is Predictive of Chemoresistance and Lymphogenic Metastasis in Penile Cancer: A Pilot Functional Study Reveals New Prognostic Biomarkers

BACKGROUND

For penile cancer (PC) there are no known molecular predictors of lymphatic spread and/or chemoresistance.

OBJECTIVE

To identify functional biomarkers that can predict malignant progression and treatment responsiveness.

DESIGN, SETTING, AND PARTICIPANTS

We used four patient-derived PC cell lines and measured invasion and capillary tube formation, chemoresponsiveness, and mRNA and protein expression. Data were further validated in E2F1 transcription factor knockdown and overexpression experiments. We quantified E2F1 transcript levels in a set of nonmetastatic tumours (NM), metastasised primary tumours (PT), and lymph node metastases (M) from 24 patients. E2F1 immunohistochemistry was performed in another set of 13 PC biopsies.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Relationships between different parameters were analysed using Student t tests. Transcript levels in patient samples were compared using Mann-Whitney U tests. Significance was set at p<0.05.

RESULTS AND LIMITATIONS

In cell lines established from lymph node metastases, E2F1 was more abundantly expressed, pRB was inactivated, and CDK2, CDK4, and cyclins D and E were elevated in comparison to cells from primary PC. Overexpression of E2F1 enhanced migratory capacity and lymphatic endothelial tubule formation, while depletion reduced invasiveness and increased chemosensitivity. VEGFR-3 and VEGF-C and mesenchymal markers were upregulated by high E2F1. E2F1 was clearly upregulated in infiltrative and metastatic primary tumours and metastases (NM vs PT, p<0.05; NM vs M, p<0.0005). E2F1 Quick scores increased from grade I to grade III tumours. A limitation of the study is the small number of patients.

CONCLUSIONS

E2F1 is a driver of invasion and lymphatic dissemination and promotes chemoresistance. E2F1-related biomarkers might assist in stratifying PC patients for different treatment regimens.

PATIENT SUMMARY

The availability of penile cancer cell lines allows molecular research on the mechanisms underlying metastasis and chemotherapy. A critical pathway involved in both features has been identified and may lead to better patient stratification for treatment selection.

Tristetraprolin regulates the decay of the hypoxia-induced vascular endothelial growth factor mRNA in ARPE-19 cells

The aim of the present study was to investigate the effects of tristetraprolin (TTP) on the vascular endothelial growth factor (VEGF) mRNA and protein expression levels in retinal pigment epithelial cells under hypoxic conditions, and to consider the possibility of using TTP as a novel treatment tool for neovascular age‑related macular degeneration (AMD). Overexpression of TTP reduced the expression and secretion levels of VEGF in ARPE‑19 cells under hypoxic conditions. TTP destabilized the VEGF mRNA by binding to adenosine and uridine‑rich elements regions in its 3'‑untranslated region. Furthermore, conditioned medium (CM) from TTP‑overexpressing ARPE‑19 cells suppressed the tube formation in human umbilical vein endothelial cells compared with hypoxic CM. These findings indicate that regulation of TTP expression may be a promising therapeutic tool for neovascular AMD, however, further research is required.

Long non-coding RNA HULC promotes tumor angiogenesis in liver cancer by up-regulating sphingosine kinase 1 (SPHK1)

Highly up-regulated in liver cancer (HULC) is a long non-coding RNA (lncRNA). We found that HULC up-regulated sphingosine kinase 1 (SPHK1), which is involved in tumor angiogenesis. Levels of HULC were positively correlated with levels of SPHK1 and its product, sphingosine-1-phosphate (S1P), in patients HCC samples. HULC increased SPHK1 in hepatoma cells. Chicken chorioallantoic membrane (CAM) assays revealed that si-SPHK1 remarkably blocked the HULC-enhanced angiogenesis. Mechanistically, HULC activated the promoter of SPHK1 in hepatoma cells through the transcription factor E2F1. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA) further showed that E2F1 was capable of binding to the E2F1 element in the SPHK1 promoter. HULC increased the expression of E2F1 in hepatoma cells and levels of HULC were positively correlated with those of E2F1 in HCC tissues. Intriguingly, HULC sequestered miR-107, which targeted E2F1 mRNA 3′UTR, by complementary base pairing. Functionally, si-SPHK1 remarkably abolished the HULC-enhanced tumor angiogenesis in vitro and in vivo. Taken together, we conclude that HULC promotes tumor angiogenesis in liver cancer through miR-107/E2F1/SPHK1 signaling. Our finding provides new insights into the mechanism of tumor angiogenesis.

Ponatinib reduces viability, migration, and functionality of human endothelial cells

Tyrosine kinase inhibitors (TKIs) have revolutionized the prognosis of chronic myeloid leukemia. With the advent of highly efficacious therapy, the focus has shifted toward managing TKI adverse effects, such as vascular adverse events (VAEs). We used an in vitro angiogenesis model to investigate the TKI-associated VAEs. Our data show that imatinib, nilotinib, and ponatinib reduce human umbilical vein endothelial cells (HUVECs) viability. Pharmacological concentrations of ponatinib induced apoptosis, reduced migration, inhibited tube formation of HUVECs, and had a negative effect on endothelial progenitor cell (EPC) function. Furthermore, in HUVECs transfected with VEGF receptor 2 (VEGFR2), the effect of ponatinib on tube formation and on all parameters representing normal endothelial cell function was less prominent than in control cells. This is the first report regarding the pathogenesis of ponatinib-associated VAEs. The antiangiogenic effect of ponatinib, possibly mediated by VEGFR2 inhibition, as shown in our study, is another piece in the intricate puzzle of TKI-associated VAEs.

Coexpression and expression quantitative trait loci analyses of the angiogenesis gene-gene interaction network in prostate cancer

BACKGROUND

Prostate cancer (PCa) shows a substantial clinical heterogeneity. The existing risk classification for PCa prognosis based on clinical factors is not sufficient. Although some biomarkers for PCa aggressiveness have been identified, their underlying functional mechanisms are still unclear. We previously reported a gene-gene interaction network associated with PCa aggressiveness based on single nucleotide polymorphism (SNP)-SNP interactions in the angiogenesis pathway. The goal of this study is to investigate potential functional evidence of the involvement of the genes in this gene-gene interaction network.

METHODS

A total of 11 angiogenesis genes were evaluated. The crosstalks among genes were examined through coexpression and expression quantitative trait loci (eQTL) analyses. The study population is 352 Caucasian PCa patients in the Cancer Genome Atlas (TCGA) study. The pairwise coexpressions among the genes of interest were evaluated using the Spearman coefficient. The eQTL analyses were tested using the Kruskal-Wallis test.

RESULTS

Among all within gene and 55 possible pairwise gene evaluations, 12 gene pairs and one gene (MMP16) showed strong coexpression or significant eQTL evidence. There are nine gene pairs with a strong correlation (Spearman correlation ≥0.6, P<1×10^-13). The top coexpressed gene pairs are EGFR-SP1 (r=0.73), ITGB3-HSPG2 (r=0.71), ITGB3-CSF1 (r=0.70), MMP16-FBLN5 (r=0.68), ITGB3-MMP16 (r=0.65), ITGB3-ROBO1 (r=0.62), CSF1-HSPG2 (r=0.61), CSF1-FBLN5 (r=0.6), and CSF1-ROBO1 (r=0.60). One cis-eQTL in MMP16 and five trans-eQTLs (MMP16-ESR1, ESR1-ROBO1, CSF1-ROBO1, HSPG2-ROBO1, and FBLN5-CSF1) are significant with a false discovery rate q value less than 0.2.

CONCLUSIONS

These findings provide potential biological evidence for the gene-gene interactions in this angiogenesis network. These identified interactions between the angiogenesis genes not only provide information for PCa etiology mechanism but also may serve as integrated biomarkers for building a risk prediction model for PCa aggressiveness.

MicroRNA-27b, microRNA-101 and microRNA-128 inhibit angiogenesis by down-regulating vascular endothelial growth factor C expression in gastric cancers

Vascular Endothelial Growth Factor C (VEGF-C) has critical roles in angiogenesis in human cancers; however, the underlying mechanisms regulating VEGF-C expression remain largely unknown. In the present study, VEGF-C protein expression and the density of blood vessels or lymphatic vessels were determined by immunohistochemistry in 103 cases of gastric cancer tissues. Suppression of VEGF-C by miR-27b, miR-101 and miR-128 was investigated by luciferase assays, Western blot and ELISA. The miRNAs expression levels were detected in human gastric cancers by real-time quantitative PCR. Cell proliferation, migration and invasion assays were performed to assess the effect of miRNAs on gastric cancer cells and human umbilical vascular endothelial cells (HUVECs). Our data showed that high VEGF-C expression was significantly associated with increased tumor size, advanced TNM classification and clinical stage, higher microvessel density (MVD) and lymphatic density (LVD), as well as poor survival in patients with gastric cancer. Furthermore, VEGF-C was found to be a direct target gene of miR-27b, miR-101, and miR-128. The expression levels of the three miRNAs were inversely correlated with MVD. Overexpression of miR-27b, miR-101, or miR-128 suppressed migration, proliferation activity, and tube formation in HUVECs by repressing VEGF-C secretion in gastric cancer cells. We conclude that miR-27b, miR-101 and miR-128 inhibit angiogenesis by down-regulating VEGF-C expression in gastric cancers.

Increased metastasis with loss of E2F2 in Myc-driven tumors

In human breast cancer, mortality is associated with metastasis to distant sites. Therefore, it is critical to elucidate the biological mechanisms that underlie tumor progression and metastasis. Using signaling pathway signatures we previously predicted a role for E2F transcription factors in Myc induced tumors. To test this role we interbred MMTV-Myc transgenic mice with E2F knockouts. Surprisingly, we observed that the loss of E2F2 sharply increased the percentage of lung metastasis in MMTV-Myc transgenic mice. Examining the gene expression profile from these tumors, we identified genetic components that were potentially involved in mediating metastasis. These genes were filtered to uncover the genes involved in metastasis that also impacted distant metastasis free survival in human breast cancer. In order to elucidate the mechanism by which E2F2 loss enhanced metastasis we generated knockdowns of E2F2 in MDA-MB-231 cells and observed increased migration in vitro and increased lung colonization in vivo. We then examined genes that were differentially regulated between tumors from MMTV-Myc, MMTV-Myc E2F2^−/−, and lung metastases samples and identified PTPRD. To test the role of PTPRD in E2F2-mediated breast cancer metastasis, we generated a knockdown of PTPRD in MDA-MB-231 cells. We noted that decreased levels of PTPRD resulted in decreased migration in vitro and decreased lung colonization in vivo. Taken together, these data indicate that E2F2 loss results in increased metastasis in breast cancer, potentially functioning through a PTPRD dependent mechanism.

E2F1 transcription factor and its impact on growth factor and cytokine signaling

E2F1 is a transcription factor involved in cell cycle regulation and apoptosis. The transactivation capacity of E2F1 is regulated by pRb. In its hypophosphorylated form, pRb binds and inactivates DNA binding and transactivating functions of E2F1. The growth factor stimulation of cells leads to activation of CDKs (cyclin dependent kinases), which in turn phosphorylate Rb and hyperphosphorylated Rb is released from E2F1 or E2F1/DP complex, and free E2F1 can induce transcription of several genes involved in cell cycle entry, induction or inhibition of apoptosis. Thus, growth factors and cytokines generally utilize E2F1 to direct cells to either fate. Furthermore, E2F1 regulates expressions of various cytokines and growth factor receptors, establishing positive or negative feedback mechanisms. This review focuses on the relationship between E2F1 transcription factor and cytokines (IL-1, IL-2, IL-3, IL-6, TGF-beta, G-CSF, LIF), growth factors (EGF, KGF, VEGF, IGF, FGF, PDGF, HGF, NGF), and interferons (IFN-α, IFN-β and IFN-γ).

Conserved E2F mediated metastasis in mouse models of breast cancer and HER2 positive patients

To improve breast cancer patient outcome work must be done to understand and block tumor metastasis. This study leverages bioinformatics techniques and traditional genetic screens to create a novel method of discovering potential contributors of tumor progression with a focus on tumor metastasis. A database of 1172 of expression data from a variety of mouse models of breast cancer was assembled and queried using previously defined oncogenic activity signatures. This analysis revealed high activity of the E2F family of transcription factors in the MMTV-Neu mouse model. A genetic cross of MMTV-Neu mice into an E2F1 null, E2F2 null, or E2F3 heterozygous background revealed significant changes in tumor progression specifically reductions in tumor latency and metastasis with E2F1 or E2F2 loss. These findings were found to be conserved in human HER2 positive patients. Patients with high E2F1 activity were shown to have worse outcomes such as relapse free survival and distant metastasis free survival. This study shows conserved mechanisms of tumor progression in human breast cancer subtypes and analogous mouse models and underlies the importance of increased research into the characterization of and comparisons between mouse and human tumors to identify which mouse models resemble each subtype of human breast cancer.

POH1 deubiquitylates and stabilizes E2F1 to promote tumour formation

Hyperactivation of the transcriptional factor E2F1 occurs frequently in human cancers and contributes to malignant progression. E2F1 activity is regulated by proteolysis mediated by the ubiquitin–proteasome system. However, the deubiquitylase that controls E2F1 ubiquitylation and stability remains undefined. Here we demonstrate that the deubiquitylase POH1 stabilizes E2F1 protein through binding to and deubiquitylating E2F1. Conditional knockout of Poh1 alleles results in reduced E2F1 expression in primary mouse liver cells. The POH1-mediated regulation of E2F1 expression strengthens E2F1-downstream prosurvival signals, including upregulation of Survivin and FOXM1 protein levels, and efficiently facilitates tumour growth of liver cancer cells in nude mice. Importantly, human hepatocellular carcinomas (HCCs) recapitulate POH1 regulation of E2F1 expression, as nuclear abundance of POH1 is increased in HCCs and correlates with E2F1 overexpression and tumour growth. Thus, our study suggests that the hyperactivated POH1–E2F1 regulation may contribute to the development of liver cancer.

The transcription factor E2F1 controls the expression of multiple genes and is frequently overactivated in cancer. Here, the authors show that E2F1 is deubiquitinated by POH1 and that this enhances the role of E2F1 in cell survival, and contributes to the pathogenesis of liver cancer.

Epigenetic factor EPC1 is a master regulator of DNA damage response by interacting with E2F1 to silence death and activate metastasis-related gene signatures

Transcription factor E2F1 is a key regulator of cell proliferation and apoptosis. Recently, it has been shown that aberrant E2F1 expression often detectable in advanced cancers contributes essentially to cancer cell propagation and characterizes the aggressive potential of a tumor. Conceptually, this requires a subset of malignant cells capable of evading apoptotic death through anticancer drugs. The molecular mechanism by which the pro-apoptotic activity of E2F1 is antagonized is widely unclear. Here we report a novel function for EPC1 (enhancer of polycomb homolog 1) in DNA damage protection. Depletion of EPC1 potentiates E2F1-mediated apoptosis in response to genotoxic treatment and abolishes tumor cell motility. We found that E2F1 directly binds to the EPC1 promoter and EPC1 vice versa physically interacts with bifunctional E2F1 to modulate its transcriptional activity in a target gene-specific manner. Remarkably, nuclear-colocalized EPC1 activates E2F1 to upregulate the expression of anti-apoptotic survival genes such as BCL-2 or Survivin/BIRC5 and inhibits death-inducing targets. The uncovered cooperativity between EPC1 and E2F1 triggers a metastasis-related gene signature in advanced cancers that predicts poor patient survival. These findings unveil a novel oncogenic function of EPC1 for inducing the switch into tumor progression-relevant gene expression that may help to set novel therapies.

Camptothecin suppresses expression of matrix metalloproteinase-9 and vascular endothelial growth factor in DU145 cells through PI3K/Akt-mediated inhibition of NF-κB activity and Nrf2-dependent induction of HO-1 expression

Though camptothecin (CPT) possesses potent anti-inflammatory, immunomodulatory, anticancerous, and antiproliferative effects, little is known about the mechanism by which CPT regulates the expression of matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF). Therefore, the current study aimed to investigate the effects of CPT on the expression of MMP-9 and VEGF, which are important factors for the invasion of tumors. In vitro application of CPT resulted in a slight inhibition of cell proliferation and a significant reduction in the matrigel invasion of DU145 cells. Treatment with CPT also downregulated phorbol-12-myristate-13-acetate (PMA)- and tumor necrosis factor-α (TNF-α)-induced MMP-9 and VEGF expression by inhibiting nuclear factor-κB (NF-κB) activity. Downregulation of phosphoinositide 3-kinase (PI3K)/Akt phosphorylation in response to CPT was revealed as an upstream pathway regulating the expression of MMP-9 and VEGF accompanying the inhibition of NF-κB activity. We further confirmed that CPT inhibits PMA-induced MMP-9 and VEGF expression by upregulating nuclear factor-erythroid related factor-2 (Nrf2)-mediated heme oxygenase-1 (HO-1) induction. Taken together, these data indicate that CPT inhibits the invasion of cancer cells accompanied by suppression of MMP-9 and VEGF production by suppressing the PI3K/Akt-mediated NF-κB pathway and enhancing the Nrf2-dependent HO-1 pathway, suggesting that CPT may be a good candidate to inhibit MMP-9 and VEGF expression.