Atypical E2fs control lymphangiogenesis through transcriptional regulation of Ccbe1 and Flt4

Association of 10 VEGF Family Genes with Alzheimer's Disease Endophenotypes at Single Cell Resolution

The cell-type specific role of the vascular endothelial growth factors (VEGFs) in the pathogenesis of Alzheimer's disease (AD) is not well characterized. In this study, we utilized a single-nucleus RNA sequencing dataset from Dorsolateral Prefrontal Cortex (DLFPC) of 424 donors from the Religious Orders Study and Memory and Aging Project (ROS/MAP) to investigate the effect of 10 VEGF genes ( VEGFA, VEGFB, VEGFC, VEGFD, PGF, FLT1, FLT4, KDR, NRP1 , and NRP2 ) on AD endophenotypes. Mean age of death was 89 years, among which 68% were females, and 52% has AD dementia. Negative binomial mixed models were used for differential expression analysis and for association analysis with β-amyloid load, PHF tau tangle density, and both cross-sectional and longitudinal global cognitive function. Intercellular VEGF-associated signaling was profiled using CellChat. We discovered prefrontal cortical FLT1 expression was upregulated in AD brains in both endothelial and microglial cells. Higher FLT1 expression was also associated with worse cross-sectional global cognitive function, longitudinal cognitive trajectories, and β-amyloid load. Similarly, higher endothelial FLT4 expression was associated with more β-amyloid load. In contrast to the receptors, VEGFB showed opposing effects on β-amyloid load whereby higher levels in oligodendrocytes was associated with high amyloid burden, while higher levels in inhibitory neurons was associated with lower amyloid burden. Finally, AD cells showed significant reduction in overall VEGF signaling comparing to those from cognitive normal participants. Our results highlight key changes in VEGF receptor expression in endothelial and microglial cells during AD, and the potential protective role of VEGFB in neurons.

Apelin-VEGF-C mRNA delivery as therapeutic for the treatment of secondary lymphedema

Secondary lymphedema (LD) corresponds to a severe lymphatic dysfunction leading to the accumulation of fluid and fibrotic adipose tissue in a limb. Here, we identified apelin (APLN) as a powerful molecule for regenerating lymphatic function in LD. We identified the loss of APLN expression in the lymphedematous arm compared to the normal arm in patients. The role of APLN in LD was confirmed in APLN knockout mice, in which LD is increased and associated with fibrosis and dermal backflow. This was reversed by intradermal injection of APLN-lentivectors. Mechanistically, APLN stimulates lymphatic endothelial cell gene expression and induces the binding of E2F8 transcription factor to the promoter of CCBE1 that controls VEGF-C processing. In addition, APLN induces Akt and eNOS pathways to stimulate lymphatic collector pumping. Our results show that APLN represents a novel partner for VEGF-C to restore lymphatic function in both initial and collecting vessels. As LD appears after cancer treatment, we validated the APLN-VEGF-C combination using a novel class of nonintegrative RNA delivery LentiFlash® vector that will be evaluated for phase I/IIa clinical trial.

Copper nanoparticles and silver nanoparticles impair lymphangiogenesis in zebrafish

Lymphatic system distributes in almost all vertebrate tissues and organs, and plays important roles in the regulation of body fluid balance, lipid absorption and immune monitoring. Although CuNPs or AgNPs accumulation has been reported to be closely associated with delayed hatching and motor dysfunction in zebrafish embryos, their biological effects on lymphangiogenesis remain unknown. In this study, thoracic duct was observed to be partially absent in both CuNPs and AgNPs stressed zebrafish larvae. Specifically, CuNPs stress induced hypermethylation of E2F7/8 binding sites on CCBE1 promoters via their producing ROS, thereby leading to the reduction of binding enrichment of E2F7/8 on CCBE1 promoter and its subsequently reduced expression, then resulting in defective lymphatic vessel formation. Differently, AgNPs stress induced down-regulated CCBE1 expression via down-regulating mRNA and protein levels of E2F7/8 transcription factors, thereby resulting in defective lymphatic vessel formation. This study may be the first to demonstrate that CuNPs and AgNPs damaged lymphangiogenesis during zebrafish embryogenesis, mechanistically, CuNPs epigenetically regulated the expression of lymphangiogenesis regulator CCBE1 via hypermethylating its promoter binding sites of E2F7/8, while AgNPs via regulating E2F7/8 expression. Meanwhile, overexpression of ccbe1 mRNA effectively rescued the lymphangiogenesis defects in both AgNPs and CuNPs stressed larvae, while overexpression of e2f7/8 mRNA effectively rescued the lymphangiogenesis defects in AgNPs rather than CuNPs stressed larvae. The results in this study will shed some light on the safety assessment of nanomaterials applied in medicine and on the ecological security assessments of nanomaterials. Video Abstract.

Interactions between genes altered during cardiotoxicity and neurotoxicity in zebrafish revealed using induced network modules analysis

As the manufacturing and development of new synthetic compounds increase to keep pace with the expanding global demand, adverse health effects due to these compounds are emerging as critical public health concerns. Zebrafish have become a prominent model organism to study toxicology due to their genomic similarity to humans, optical clarity, well-defined developmental stages, short generation time, and cost-effective maintenance. It also provides a shorter time frame for in vivo toxicology evaluation compared to the mammalian experimental systems. Here, we used meta-analysis to examine the alteration in genes during cardiotoxicity and neurotoxicity in zebrafish, caused by chemical exposure of any kind. First, we searched the literature comprehensively for genes that are altered during neurotoxicity and cardiotoxicity followed by meta-analysis using ConsensusPathDB. Since constant communication between the heart and the brain is an important physiological phenomenon, we also analyzed interactions among genes altered simultaneously during cardiotoxicity and neurotoxicity using induced network modules analysis in ConsensusPathDB. We observed inflammation and regeneration as the major pathways involved in cardiotoxicity and neurotoxicity. A large number of intermediate genes and input genes anchored in these pathways are molecular regulators of cell cycle progression and cell death and are implicated in tumor manifestation. We propose potential predictive biomarkers for neurotoxicity and cardiotoxicity and the major pathways potentially implicated in the manifestation of a particular toxicity phenotype.

Whole blood transcript and protein abundance of the vascular endothelial growth factor family relate to cognitive performance

The vascular endothelial growth factor (VEGF) family of genes has been implicated in the clinical development of Alzheimer's Disease (AD). A previous study identified associations between gene expression of VEGF family members in the prefrontal cortex and cognitive performance and AD pathology. This study explored if those associations were also observed in the blood. Consistent with previous observations in brain tissue, higher blood gene expression of placental growth factor (PGF) was associated with a faster rate of memory decline (p=0.04). Higher protein abundance of FMS-related receptor tyrosine kinase 4 (FLT4) in blood was associated with biomarker levels indicative of lower amyloid and tau pathology, opposite the direction observed in brain. Also, higher gene expression of VEGFB in blood was associated with better baseline memory (p=0.008). Notably, we observed that higher gene expression of VEGFB in blood was associated with lower expression of VEGFB in the brain (r=-0.19, p=0.02). Together, these results suggest that the VEGFB, FLT4, and PGF alterations in the AD brain may be detectable in the blood compartment.

CCBE1 in Cardiac Development and Disease

The collagen- and calcium-binding EGF-like domains 1 (CCBE1) is a secreted protein extensively described as indispensable for lymphangiogenesis during development enhancing VEGF-C signaling. In human patients, mutations in CCBE1 have been found to cause Hennekam syndrome, an inherited disease characterized by malformation of the lymphatic system that presents a wide variety of symptoms such as primary lymphedema, lymphangiectasia, and heart defects. Importantly, over the last decade, an essential role for CCBE1 during heart development is being uncovered. In mice, Ccbe1 expression was initially detected in distinct cardiac progenitors such as first and second heart field, and the proepicardium. More recently, Ccbe1 expression was identified in the epicardium and sinus venosus (SV) myocardium at E11.5–E13.5, the stage when SV endocardium–derived (VEGF-C dependent) coronary vessels start to form. Concordantly, CCBE1 is required for the correct formation of the coronary vessels and the coronary artery stem in the mouse. Additionally, Ccbe1 was found to be enriched in mouse embryonic stem cells (ESC) and revealed as a new essential gene for the differentiation of ESC-derived early cardiac precursor cell lineages. Here, we bring an up-to-date review on the role of CCBE1 in cardiac development, function, and human disease implications. Finally, we envisage the potential of this molecule’s functions from a regenerative medicine perspective, particularly novel therapeutic strategies for heart disease.

Copper stress impairs angiogenesis and lymphangiogenesis during zebrafish embryogenesis by down-regulating pERK1/2-foxm1-MMP2/9 axis and epigenetically regulating ccbe1 expression

Molecular transport and cell circulation between tissues and organs through blood and lymphatic vessels are essential for physiological homeostasis in vertebrates. Despite the report of its association with vessel formation in solid tumors, the biological effects of Copper (Cu) accumulation on angiogenesis and lymphangiogenesis during embryogenesis are still unknown. In this study, we unveiled that intersegmental blood circulation was partially blocked in Cu²⁺-stressed zebrafish embryos and cell migration and tube formation were impaired in Cu²⁺-stressed mammalian HUVECs. Specifically, Cu²⁺-stressed embryos showed down-regulation in the expression of amotl2 and its downstream pERK1/2-foxm1-MMP2/9 regulatory axis, and knockdown/knockout of foxm1 in zebrafish embryos phenocopied angiogenesis defects, while FOXM1 knockdown HUVECs phenocopied cell migration and tube formation defects, indicating that excessive Cu²⁺-induced angiogenesis defects and blocked cell migration via down-regulating amotl2-pERK1/2-foxm1-MMP2/9 regulatory axis in both embryos and mammalian cells. Additionally, thoracic duct was revealed to be partially absent in Cu²⁺-stressed zebrafish embryos. Specifically, Cu²⁺-stressed embryos showed down-regulation in the expression of ccbe1 (a gene with pivotal function in lymphangiogenesis) due to the hypermethylation of the E2F7/8 binding sites on ccbe1 promoter to reduce their binding enrichment on the promoter, contributing to the potential mechanisms for down-regulation of ccbe1 and the formation of lymphangiogenesis defects in Cu²⁺-stressed embryos and mammalian cells. These integrated data demonstrate that Cu²⁺ stress impairs angiogenesis and lymphangiogenesis via down-regulation of pERK1/2-foxm1-MMP2/9 axis and epigenetic regulation of E2F7/8 transcriptional activity on ccbe1 expression, respectively.

Esm1 and Stc1 as Angiogenic Factors Responsible for Protective Actions of Adipose-Derived Stem Cell Sheets on Chronic Heart Failure After Rat Myocardial Infarction

BACKGROUND

Although adipose-derived stem cell (ADSC) sheets improve the cardiac function after myocardial infarction (MI), underlying mechanisms remain to be elucidated. The aim of this study was to determine the fate of transplanted ADSC sheets and candidate angiogenic factors released from ADSCs for their cardiac protective actions.Methods and Results:MI was induced by ligation of the left anterior descending coronary artery. Sheets of transgenic (Tg)-ADSCs expressing green fluorescence protein (GFP) and luciferase or wild-type (WT)-ADSCs were transplanted 1 week after MI. Both WT- and Tg-ADSC sheets improved cardiac functions evaluated by echocardiography at 3 and 5 weeks after MI. Histological examination at 5 weeks after MI demonstrated that either sheet suppressed fibrosis and increased vasculogenesis. Luciferase signals from Tg-ADSC sheets were detected at 1 and 2 weeks, but not at 4 weeks, after transplantation. RNA sequencing of PKH (yellow-orange fluorescent dye with long aliphatic tails)-labeled Tg-ADSCs identified mRNAs of 4 molecules related to angiogenesis, including those of Esm1 and Stc1 that increased under hypoxia. Administration of Esm1 or Stc1 promoted tube formation by human umbilical vein endothelial cells.

CONCLUSIONS

ADSC sheets improved cardiac contractile functions after MI by suppressing cardiac fibrosis and enhancing neovascularization. Transplanted ADSCs existed for >2 weeks on MI hearts and produced the angiogenic factors Esm1 and Stc1, which may improve cardiac functions after MI.

Timed Ang2-Targeted Therapy Identifies the Angiopoietin-Tie Pathway as Key Regulator of Fatal Lymphogenous Metastasis

Recent clinical and preclinical advances have highlighted the existence of a previously hypothesized lymphogenous route of metastasis. However, due to a lack of suitable preclinical modeling tools, its contribution to long-term disease outcome and relevance for therapy remain controversial. Here, we established a genetically engineered mouse model (GEMM) fragment-based tumor model uniquely sustaining a functional network of intratumoral lymphatics that facilitates seeding of fatal peripheral metastases. Multiregimen survival studies and correlative patient data identified primary tumor-derived Angiopoietin-2 (Ang2) as a potent therapeutic target to restrict lymphogenous tumor cell dissemination. Mechanistically, tumor-associated lymphatic endothelial cells (EC), in contrast to blood vascular EC, were found to be critically addicted to the Angiopoietin-Tie pathway. Genetic manipulation experiments in combination with single-cell mapping revealed agonistically acting Ang2-Tie2 signaling as key regulator of lymphatic maintenance. Correspondingly, acute presurgical Ang2 neutralization was sufficient to prolong survival by regressing established intratumoral lymphatics, hence identifying a therapeutic regimen that warrants further clinical evaluation. SIGNIFICANCE: Exploiting multiple mouse tumor models including a unique GEMM-derived allograft system in combination with preclinical therapy designs closely matching the human situation, this study provides fundamental insight into the biology of tumor-associated lymphatic EC and defines an innovative presurgical therapeutic window of migrastatic Ang2 neutralization to restrict lymphogenous metastasis.This article is highlighted in the In This Issue feature, p. 211.

E2F8 Induces Cell Proliferation and Invasion through the Epithelial-Mesenchymal Transition and Notch Signaling Pathways in Ovarian Cancer

Background: Despite the recent research implicating E2F8 (E2F Transcription Factor 8) in cancer, the role of E2F8 in the progression of ovarian cancer has remained unclear. Hence, we explored the bio-functional effects of E2F8 knockdown on ovarian cancer cell lines in vitro and in vivo. Methods: The expression of E2F8 was compared between ovarian cancer and noncancer tissues, and its association with the progression-free survival of ovarian cancer patients was analyzed. To demonstrate the function of E2F8 in cell proliferation, migration, and invasion, we employed RNA interference to suppress E2F8 expression in ovarian cancer cell lines. Finally, the effect of E2F8 knockdown was investigated in a xenograft mouse model of ovarian cancer. Results: Ovarian cancer tissue exhibited significantly higher E2F8 expression compared to that of normal ovarian tissue. Clinical data showed that E2F8 was a significant predictor of progression-free survival. Moreover, the prognosis of the ovarian cancer patients with high E2F8 expression was poorer than that of the patients with low E2F8 expression. In vitro experiments using E2F8-knockdown ovarian cancer cell lines demonstrated that E2F8 knockdown inhibited cell proliferation, migration, and tumor invasion. Additionally, E2F8 was a potent inducer and modulator of the expression of epithelial–mesenchymal transition and Notch signaling pathway-related markers. We confirmed the function of E2F8 in vivo, signifying that E2F8 knockdown was significantly correlated with reduced tumor size and weight. Conclusions: Our findings indicate that E2F8 is highly correlated with ovarian cancer progression. Hence, E2F8 can be utilized as a prognostic marker and therapeutic target against ovarian malignancy.

Formation and Growth of Cardiac Lymphatics during Embryonic Development, Heart Regeneration, and Disease

The lymphatic system plays crucial roles in regulating fluid homeostasis, immune surveillance, and lipid transport. As is in most of the body's organs, the heart possesses an extensive lymphatic network. Moreover, a robust lymphangiogenic response has been shown to take place following myocardial infarction, highlighting cardiac lymphatics as potential targets for therapeutic intervention. Yet, the unique molecular properties and functions of the heart's lymphatic system have only recently begun to be addressed. In this review, we discuss the mechanisms underlying the formation and growth of cardiac lymphatics during embryonic development and describe their characteristics across species. We further summarize recent findings highlighting diverse cellular origins for cardiac lymphatic endothelial cells and how they integrate to form a single functional lymphatic network. Finally, we outline novel therapeutic avenues aimed at enhancing lymphatic vessel formation and integrity following cardiac injury, which hold great promise for promoting healing of the infarcted heart.

Harnessing Gene Expression Profiles for the Identification of Ex Vivo Drug Response Genes in Pediatric Acute Myeloid Leukemia

Novel treatment strategies are of paramount importance to improve clinical outcomes in pediatric AML. Since chemotherapy is likely to remain the cornerstone of curative treatment of AML, insights in the molecular mechanisms that determine its cytotoxic effects could aid further treatment optimization. To assess which genes and pathways are implicated in tumor drug resistance, we correlated ex vivo drug response data to genome-wide gene expression profiles of 73 primary pediatric AML samples obtained at initial diagnosis. Ex vivo response of primary AML blasts towards cytarabine (Ara C), daunorubicin (DNR), etoposide (VP16), and cladribine (2-CdA) was associated with the expression of 101, 345, 206, and 599 genes, respectively (p < 0.001, FDR 0.004–0.416). Microarray based expression of multiple genes was technically validated using qRT-PCR for a selection of genes. Moreover, expression levels of BRE, HIF1A, and CLEC7A were confirmed to be significantly (p < 0.05) associated with ex vivo drug response in an independent set of 48 primary pediatric AML patients. We present unique data that addresses transcriptomic analyses of the mechanisms underlying ex vivo drug response of primary tumor samples. Our data suggest that distinct gene expression profiles are associated with ex vivo drug response, and may confer a priori drug resistance in leukemic cells. The described associations represent a fundament for the development of interventions to overcome drug resistance in AML, and maximize the benefits of current chemotherapy for sensitive patients.

Identification and Characterization of a Novel Protein ASP-3 Purified from Arca subcrenata and Its Antitumor Mechanism

Diverse bioactive substances derived from marine organisms have been attracting growing attention. Besides small molecules and polypeptides, numerous studies have shown that marine proteins also exhibit antitumor activities. Small anticancer proteins can be expressed in vivo by viral vectors to exert local and long-term anticancer effects. Herein, we purified and characterized a novel protein (ASP-3) with unique antitumor activity from Arca subcrenata Lischke. The ASP-3 contains 179 amino acids with a molecular weight of 20.6 kDa. The spectral characterization of ASP-3 was elucidated using Fourier Transform infrared spectroscopy (FTIR) and Circular Dichroism (CD) spectroscopy. Being identified as a sarcoplasmic calcium-binding protein, ASP-3 exhibited strong inhibitory effects on the proliferation of Human hepatocellular carcinoma (HepG2) cells with an IC50 value of 171.18 ± 18.59 μg/mL, measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The RNA-seq analysis showed that ASP-3 regulated the vascular endothelial growth factor receptor (VEGFR) signaling pathway in HepG2 cells. Immunofluorescence results indicated that ASP-3 effectively reduced VEGFR2 phosphorylation in HepG2 cells and affected the downstream components of VEGF signaling pathways. The surface plasmon resonance (SPR) analysis further demonstrated that ASP-3 direct interacted with VEGFR2. More importantly, the therapeutic potential of ASP-3 as an anti-angiogenesis agent was further confirmed by an in vitro model using VEGF-induced tube formation assay of human umbilical vein endothelial cells (HUVECs), as well as an in vivo model using transgenic zebrafish model. Taken together, the ASP-3 provides a good framework for the development of even more potent anticancer proteins and provides important weapon for cancer treatment using novel approaches such as gene therapy.

Common responses of fish embryos to metals: an integrated analysis of transcriptomes and methylomes in zebrafish embryos under the stress of copper ions or silver nanoparticles

This study demonstrated the common responses of differentially expressed genes (DEGs) and differentially methylated regions (DMRs) under Cu²⁺ or AgNPs stresses in zebrafish, and verified the correlation of the gene transcription and the methylation status of some common DMGs.

Blood flow-induced Notch activation and endothelial migration enable vascular remodeling in zebrafish embryos

Arteries and veins are formed independently by different types of endothelial cells (ECs). In vascular remodeling, arteries and veins become connected and some arteries become veins. It is unclear how ECs in transforming vessels change their type and how fates of individual vessels are determined. In embryonic zebrafish trunk, vascular remodeling transforms arterial intersegmental vessels (ISVs) into a functional network of arteries and veins. Here we find that, once an ISV is connected to venous circulation, venous blood flow promotes upstream migration of ECs that results in displacement of arterial ECs by venous ECs, completing the transformation of this ISV into a vein without trans-differentiation of ECs. Arterial blood flow initiated in two neighboring ISVs prevents their transformation into veins by activating Notch signaling in ECs. Together, different responses of ECs to arterial and venous blood flow lead to formation of a balanced network with equal numbers of arteries and veins.

The clinical significance of CCBE1 expression in human colorectal cancer

Purpose

The identification and discovery of prognostic markers for colorectal cancer (CRC) are of great clinical significance. CCBE1 is expressed in various tumors and its expression correlates with lymphangiogenesis and angiogenesis. However, the association between CCBE1 expression and CRC outcome has not been reported. The aim of this study was to investigate clinical significance of CCBE1 expression in CRC.

Patients and methods

CCBE1 expression was examined in 30 pairs of fresh CRC tissues and compared with adjacent normal (AN) tissues using quantitative real-time PCR (qRT-PCR), Western blotting and immunohistochemistry (IHC) staining. Tissue microarray immunohistochemical staining was used to study the CCBE1 expression characteristics of 204 CRC patient samples collected from January 2002 to December 2007, and the relationship of CCBE1 with clinicopathological features and prognosis of CRC was analyzed.

Results

CCBE1 was highly expressed in CRC tissues compared with matched AN tissues (P=0.001). Moreover, high expression of CCBE1 was significantly associated with tumor differentiation, lymph node metastasis, vascular invasion, liver metastasis and TNM stage in CRC patients (P≤0.01). Kaplan-Meier survival analysis revealed that high CCBE1 expression, poor tumor differentiation, lymph node metastasis and vascular invasion were significantly associated (all P<0.001) with poor prognosis for patients. Furthermore, univariate and multivariate Cox analysis revealed that high CCBE1 expression, poor tumor differentiation, lymph node metastasis and vascular invasion were independent risk factors for both overall survival (OS) and disease-free survival (DFS) of CRC patients (all P<0.05). OS and DFS of 267 CRC patients from The Cancer Genome Atlas (TCGA) database showed the same trend (log-rank P=6e-04, HR [high] =2.4; log-rank P=0.0081, HR [high] =1.9).

Conclusion

High levels of CCBE1 contribute to the aggressiveness and poor prognosis of CRC. CCBE1 can serve as a novel potential biomarker to predict CRC patients' prognosis.

E2F transcription factor 8 promotes cell proliferation via CCND1/p21 in esophageal squamous cell carcinoma

Purpose

E2F transcription factor 8 (E2F8) is a novel member of the E2F family, but its function in esophageal squamous cell carcinoma (ESCC) remains unclear. This study aimed to research the function of E2F8 in ESCC.

Materials and methods

We used quantitative real-time PCR and Western blot analyses to detect the expression pattern of E2F8 in ESCC. The effects of E2F8 on proliferation were investigated by Cell Counting Kit-8, 5-ethynyl-2′-deoxyuridine, and colony formation assays. We also confirmed the function of E2F8 in vivo.

Results

E2F8 expression was upregulated in ESCC, and promoted cell proliferation and influenced the expression of CCND1/p21. Downregulation of E2F8 expression inhibited cell proliferation in vivo.

Conclusion

E2F8 was identified as a new potential oncogene in ESCC.

Detection of Pro- and Antiangiogenic Factors in the Human Sclera

PURPOSE

Avascular tissues can be used to identify antilymph- or antihemangiogenic factors. The human sclera-the outer covering layer of the eye, lacks lymphatic vessels and contains only a superficial network of blood vessels and was used here to identify endogenous antiangiogenic factors.

METHODS

Expression levels of a panel of 96 known pro- and antiangiogenic factors were analyzed in 12 scleral or conjunctival control samples from normal human donors using real-time PCR. In vitro, scleral homogenate was cocultured with blood- and lymphatic endothelial cells (BECs and LECs) and immunohistochemistry was performed of scleral fibroblasts and BECs.

RESULTS

Three antiangiogenic factors were significantly upregulated in the human sclera compared to the conjunctiva, including FBLN5 (fibulin 5), SERPINF1 (serpin peptidase inhibitor, clade F, member 1 = pigment epithelium derived factor) and TIMP2 (Tissue inhibitor of metalloproteinases 2). Six proangiogenic factors were significantly downregulated in the sclera, including FLT4 (Fms-related tyrosine kinase 4=VEGF-R3), HGF (hepatocyte growth factor), KIT (CD117 / c-kit), PROX1 (prospero homeobox 1), SEMA3F (semaphorin-3F) and TGFA (transforming growth factor alpha). In vitro, scleral homogenate inhibited the growth of both BECs and LECs. Immunohistochemistry labeling of three major antiangiogenic factors from scleral tissue confirmed TIMP3 and PEDF expression both in scleral fibroblasts and in blood endothelial cells, whereas TIMP2 was not detectable.

CONCLUSION

Balancing anti- and proangiogenic factors actively regulates human scleral avascularity, inhibits endothelial cell growth in vitro, and thus may help maintaining the vascular privilege of the inner eye.

The role of E2F8 in the human placenta

Recent studies have reported that E2F transcription factor (E2F) 8, an atypical E2F transcription factor, serves a critical role in promoting the growth and development of the murine placenta. However, the function of E2F8 in the human placenta remains unknown. Invasion of extravillous trophoblasts (EVTs) into the maternal decidua is known to be important for the development of the human placenta. To investigate the role of E2F8 in human placental development, E2F8 localisation was examined in the human placenta and E2F8 mRNA expression was detected in primary cultured EVTs. The human EVT cell line, HTR‑8/SVneo, was divided into two groups and treated separately, one with retrovirus expressing short hairpin (sh)‑RNA against E2F8 (shE2F8 cells) and the other with non‑target control shRNA (shControl cells). The cell functions, including cell cycle, proliferation, invasion and adhesion, were compared between the shE2F8 and shControl cells. A histological examination revealed that E2F8 was localised in the decidua cells, EVTs, and cytotrophoblasts in the placenta. E2F8 mRNA was confirmed to be expressed in cultured primary EVTs. No significant difference was observed in the cell cycle, proliferation or adhesion between the shE2F8 and shControl cells. The invasive ability was ~2‑fold higher in the shE2F8 cells when compared with the shControl cells (P<0.01). Production of matrix metalloproteinase‑1 was significantly increased in the shE2F8 cells when compared with the shControl cells (P<0.05). Taken together, E2F8 is present in the EVTs of the human placenta, but, unlike murine placenta, it may suppress the invasiveness of EVTs. E2F8 was also present in cytotrophoblasts in cell columns, which have no invasive ability and differentiate into EVTs. In conclusion, E2F8 also exists in the human placenta, and its function may be different from that in the murine placenta, although further investigation is required.

Recent advances in understanding lymphangiogenesis and metabolism

The blood and lymphatic vasculatures are vital to the maintenance of homeostasis. The interaction between two vascular networks throughout the body is precisely controlled to enable oxygen and nutrient delivery, removal of carbon dioxide and metabolic waste, drainage of interstitial fluid, transport of immune cells, and other key activities. Recent years have seen an explosion of information dealing with the development and function of the lymphatic system. The growth of lymphatic vessels, termed lymphangiogenesis, is a high-energy requirement process that involves sprouting, proliferation, migration, and remodeling of lymphatic endothelial cells and capillaries. Although there has been substantial progress in identifying growth factors and their downstream signaling pathways that control lymphangiogenesis, the role of metabolic processes during lymphangiogenesis and their links to growth factor signaling are poorly understood. In this review, we will discuss recent work that has provided new insights into lymphatic metabolism and its role in lymphangiogenesis.

Upregulation of E2F8 promotes cell proliferation and tumorigenicity in breast cancer by modulating G1/S phase transition

E2F transcription factors are involved in cell cycle regulation and synthesis of DNA in mammalian cells, and simultaneously play important roles in the development and progression of cancer when dysregulated. E2F8, a novel identified E2F family member, was found to be associated with the progression of several human cancers; however, the biological role and clinical significance of E2F8 in breast cancer remain to be further elucidated. Herein, we report that E2F8 is robustly elevated in breast cancer cell lines and clinical breast cancer tissue samples, respectively. The high expression level of E2F8 significantly correlates with clinical progression (P = 0.001), poor patient survival (P < 0.001) and a high Ki67 staining index (P = 0.008) in 187 human breast cancer specimens. Furthermore, we find that overexpressing E2F8 promotes, whereas silencing E2F8 suppresses, the proliferation and tumorigenicity of breast cancer cells both in vitro and in vivo. We further demonstrate that E2F8 transcriptionally upregulates CCNE1 and CCNE2 via directly interacting with their respective gene promoter, which accelerates the transition of G1 to S phase of breast cancer cells. Taken together, these findings uncover a novel biologic role and regulatory mechanism of E2F8 responsible for the progression of breast cancer, indicating E2F8 may represent a novel prognostic biomarker and therapeutic target against breast cancer.

E2F8 is a Potential Therapeutic Target for Hepatocellular Carcinoma

E2F transcriptional factors are widely expressed in a number of tissues and organs, possessing many regulatory functions related to cellular proliferation, differentiation, DNA repair, cell-cycle and cell apoptosis. E2F8 is a recently identified member of the E2F family with a duplicated DNA-binding domain feature discriminated from E2F1-6, controlling gene expression in a dimerization partner-independent manner. It is indispensable for angiogenesis, lymphangiogenesis and embryonic development. Although E2F8 and E2F7 perform complementary and overlapping functions in many cell metabolisms, E2F8, but not E2F7, overexpresses remarkably in hepatocellular carcinoma (HCC) to facilitate the HCC occurrence and development via activating a E2F1/ Cyclin D1 signaling pathway to regulate the G1- to S-phase transition of cell cycle progression or transcriptionally suppressing CDK1 to induce hepatocyte polyploidization. It also involves closely a variety of cellular physiological functions and pathological processes, which may bring a new breakthrough for the treatment of certain diseases, especially the HCC. Here, we summarize the latest progress of E2F8 on its relevant functions and mechanisms as well as potential application.

E2F8, a direct target of miR-144, promotes papillary thyroid cancer progression via regulating cell cycle

Background

Thyroid cancer is the most common malignancy of endocrine system, and papillary thyroid cancer (PTC) is the most common subtype. E2F8, a novel identified E2F family member, was reported to associate with progression of several human cancers, however, its clinical significance and biological role in PTC remain unknown.

Methods

E2F8 or miR-144 expression profiles in PTC tissues were obtained from The Cancer Genome Atlas (TCGA) datasets, and the correlation of E2F8 expression with clinicopathological features was analyzed in a cohort PTC patients. The effects of E2F8 and miR-144 on proliferation were evaluated both in vitro and in vivo. Luciferase reporter assay was used to determine E2F8 was a direct target of miR-144.

Results

E2F8 was widely upregulated in PTC tissues, and overexpression of E2F8 was correlated with more aggressive clinicopathological features. In contrast, we found that silence of E2F8 significantly suppressed proliferation of PTC cells by inducing G1-phase arrest via downregulating Cyclin D1 (CCND1) both in vitro and in vivo. We also identified miR-144 as a tumor-suppressive microRNA that directly targeted E2F8 to inhibit proliferation of PTC cells in vitro and in vivo. Moreover, miR-144 was widely downregulated in PTC, where its expression correlated inversely with E2F8 expression.

Conclusions

Our results demonstrate a new miR-144/E2F8/CCND1 regulatory axis controlling PTC development, which may offer a potential prognostic and therapeutic strategy.

Trial registration

No applicable.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0504-6) contains supplementary material, which is available to authorized users.

CCBE1 promotes GIST development through enhancing angiogenesis and mediating resistance to imatinib

Gastrointestinal stromal tumor (GIST) is the most major mesenchymal neoplasm of the digestive tract. Up to now, imatinib mesylate has been used as a standard first-line treatment for irresectable and metastasized GIST patients or adjuvant treatment for advanced GIST patients who received surgical resection. However, secondary resistance to imatinib usually happens, resulting in a major obstacle in GIST successful therapy. In this study, we first found that collagen and calcium binding EGF domains 1 (CCBE1) expression gradually elevated along with the risk degree of NIH classification, and poor prognosis emerged in the CCBE1-positive patients. In vitro experiments showed that recombinant CCBE1 protein can enhance angiogenesis and neutralize partial effect of imatinib on the GIST-T1 cells. In conclusion, these data indicated that CCBE1 may be served as a new predictor of prognosis in post-operative GIST patients and may play an important role in stimulating GIST progression.

A Multiplex Kindred with Hennekam Syndrome due to Homozygosity for a CCBE1 Mutation that does not Prevent Protein Expression

Collagen and calcium-binding EGF domain-containing protein 1 (CCBE1) bi-allelic mutations have been associated with syndromes of widespread congenital lymphatic dysplasia, including Hennekam Syndrome (HS). HS is characterized by lymphedema, lymphangiectasia, and intellectual disability. CCBE1 encodes a putative extracellular matrix protein but the HS-causing mutations have not been studied biochemically. We report two HS siblings, born to consanguineous parents of Turkish ancestry, whose clinical phenotype also includes protein losing enteropathy, painful relapsing chylous ascites, and hypogammaglobulinemia. We identified by whole exome and Sanger sequencing the homozygous CCBE1 C174Y mutation in both siblings. This mutation had been previously reported in another HS kindred from the Netherlands. In over-expression studies, we found increased intracellular expression of all forms (monomers, dimers, trimers) of the CCBE1 C174Y mutant protein, by Western blot, despite mutant mRNA levels similar to wild-type (WT). In addition, we detected increased secretion of the mutant CCBE1 protein by ELISA. We further found the mutant and WT proteins to be evenly distributed in the cytoplasm, by immunofluorescence and confocal microscopy. Finally, we found a strong decrease of lymphatic vessels, with a corresponding diminished expression of CCBE1, by immunohistochemistry of the patients' intestinal biopsies. In contrast, mucosal blood vessels and muscularis mucosae showed normal CCBE1 staining. Our findings show that the mutant CCBE1 C174Y protein is not loss-of-function by loss-of-expression.

Pressing the right buttons: signaling in lymphangiogenesis

Lymphatic vasculature is increasingly recognized as an important factor both in the regulation of normal tissue homeostasis and immune response and in many diseases, such as inflammation, cancer, obesity, and hypertension. In the last few years, in addition to the central role of vascular endothelial growth factor (VEGF)-C/VEGF receptor-3 signaling in lymphangiogenesis, significant new insights were obtained about Notch, transforming growth factor β/bone morphogenetic protein, Ras, mitogen-activated protein kinase, phosphatidylinositol 3 kinase, and Ca2+/calcineurin signaling pathways in the control of growth and remodeling of lymphatic vessels. An emerging picture of lymphangiogenic signaling is complex and in many ways distinct from the regulation of angiogenesis. This complexity provides new challenges, but also new opportunities for selective therapeutic targeting of lymphatic vasculature.