EGFL7 Mediates BMP9-Induced Sprouting Angiogenesis of Endothelial Cells Derived from Human Embryonic Stem Cells

EGFL7: An emerging biomarker with great therapeutic potential

EGFL7 is a factor involved in the regulation of various essential biological mechanisms. Endothelial cells and neurons secrete the EGFL7 protein into the extracellular matrix, where it interacts with other matrix proteins, thereby regulating several important signaling pathways. To date, extensive in vitro and in vivo studies have illuminated the central role of EGFL7 in governing major biological processes involving blood vessels and the central nervous system. Notably, EGFL7 has also emerged as a key factor in a spectrum of diseases including cancer, stroke, multiple sclerosis and preeclampsia. Its influence on various diseases and multiple regulatory pathways highlights EGFL7 as an emerging biomarker and therapeutic target. Thus, the multifaceted regulatory functions of EGFL7 will be discussed in the physiological context before delving into its involvement in the progression of different diseases. Finally, the review will provide an insight into the broad therapeutic potential of EGFL7 by describing its role as a powerful biomarker and discussing potential strategies to therapeutically target EGFL7 function in a plethora of human diseases.

Regulation of hematopoietic stem cell (HSC) proliferation by Epithelial Growth Factor Like-7 (EGFL7)

Understanding the pathways regulating normal and malignant hematopoietic stem cell (HSC) biology is important for improving outcomes for patients with hematologic disorders. Epithelial Growth Factor Like-7 (EGFL7 ) is ∼30 kDa secreted protein that is highly expressed in adult HSCs. Using Egfl7 genetic knock-out ( Egfl7 KO) mice and recombinant EGFL7 (rEGFL7) protein, we examined the role of Egfl7 in regulating normal hematopoiesis. We found that Egfl7 KO mice had decreases in overall BM cellularity resulting in significant reduction in the number of hematopoietic stem and progenitor cells (HSPCs), which was due to dysregulation of normal cell-cycle progression along with a corresponding increase in quiescence. rEGFL7 treatment rescued our observed hematopoietic defects of Egfl7 KO mice and enhanced HSC expansion after genotoxic stress such as 5-FU and irradiation. Furthermore, treatment of WT mice with recombinant EGFL7 (rEGFL7) protein expands functional HSCs evidenced by an increase in transplantation potential. Overall, our data demonstrates a role for EGFL7 in HSC expansion and survival and represents a potential strategy for improving transplant engraftment or recovering bone marrow function after stress.

An organotypic atlas of human vascular cells

The human vascular system, comprising endothelial cells (ECs) and mural cells, covers a vast surface area in the body, providing a critical interface between blood and tissue environments. Functional differences exist across specific vascular beds, but their molecular determinants across tissues remain largely unknown. In this study, we integrated single-cell transcriptomics data from 19 human organs and tissues and defined 42 vascular cell states from approximately 67,000 cells (62 donors), including angiotypic transitional signatures along the arterial endothelial axis from large to small caliber vessels. We also characterized organotypic populations, including splenic littoral and blood-brain barrier ECs, thus clarifying the molecular profiles of these important cell states. Interrogating endothelial-mural cell molecular crosstalk revealed angiotypic and organotypic communication pathways related to Notch, Wnt, retinoic acid, prostaglandin and cell adhesion signaling. Transcription factor network analysis revealed differential regulation of downstream target genes in tissue-specific modules, such as those of FOXF1 across multiple lung vascular subpopulations. Additionally, we make mechanistic inferences of vascular drug targets within different vascular beds. This open-access resource enhances our understanding of angiodiversity and organotypic molecular signatures in human vascular cells, and has therapeutic implications for vascular diseases across tissues.

Overexpression of EGFL7 promotes angiogenesis and nerve regeneration in peripheral nerve injury

Peripheral nerve injury (PNI) often leads to significant functional impairment. Here, we investigated the impact of epidermal growth factor-like domain-containing protein 7 (EGFL7) on angiogenesis and nerve regeneration following PNI. Using a sciatic nerve injury model, we assessed nerve function using the sciatic nerve function index. We analyzed the expression levels of EGFL7, forkhead box proteins A1 (FOXA1), nerve growth factor (NGF), brain-derived neurotrophic factors (BDNF), Neurofilament 200 (NF200), myelin protein zero (P0), cell adhesion molecule 1 (CD31), vascular endothelial growth factor (VEGF), and NOTCH-related proteins in tissues and cells. Cell proliferation, migration, and angiogenesis were evaluated through cell counting kit assays, 5-ethynyl-2'deoxyuridine staining, and Transwell assays. We investigated the binding of FOXA1 to the EGFL7 promoter using dual-luciferase assays and chromatin immunoprecipitation. We observed decreased EGFL7 expression and increased FOXA1 expression in PNI, and EGFL7 overexpression alleviated gastrocnemius muscle atrophy, increased muscle weight, and improved motor function. Additionally, EGFL7 overexpression enhanced Schwann cell and endothelial cell proliferation and migration, promoted tube formation, and upregulated NGF, BDNF, NF200, P0, CD31, and VEGF expression. FOXA1 was found to bind to the EGFL7 promoter region, inhibiting EGFL7 expression and activating the NOTCH signaling pathway. Notably, FOXA1 overexpression counteracted the effects of EGFL7 on Schwann cells and endothelial cells. In conclusion, EGFL7 holds promise as a therapeutic molecule for treating sciatic nerve injury.

Elevated circulating BMP9 aggravates pulmonary angiogenesis in hepatopulmonary syndrome rats through ALK1-Endoglin-Smad1/5/9 signalling

BACKGROUND

Bone morphogenetic protein 9 (BMP9) is a hepatokine that plays a pivotal role in the progression of liver diseases. Moreover, an increasing number of studies have shown that BMP9 is associated with hepatopulmonary syndrome (HPS), but its role in HPS is unclear. Here, we evaluated the influence of CBDL on BMP9 expression and investigated potential mechanisms of BMP9 signalling in HPS.

METHODS

We profiled the circulating BMP9 levels in common bile duct ligation-induced HPS rat model, and then investigated the effects and mechanisms of HPS rat serum on pulmonary vascular endothelial dysfunction in rat model, as well as in primarily cultured rat pulmonary microvascular endothelial cells.

RESULTS

Our data revealed that circulating BMP9 levels were significantly increased in the HPS rats compared to control group. Besides, the elevated BMP9 in HPS rat serum was not only crucial for promoting endothelial cell proliferation and tube formation through the activin receptor-like kinase1 (ALK1)-Endoglin-Smad1/5/9 pathway, but also important for accumulation of monocytes. Treatments with ALK1-Fc or silencing ALK1 expression to inhibit the BMP9 signalling pathway effectively eliminated these effects. In agreement with these observations, increased circulating BMP9 was associated with an increase in lung vessel density and accumulation of pro-angiogenic monocytes in the microvasculature in HPS rats.

CONCLUSIONS

This study provided evidence that elevated circulating BMP9, secreted from the liver, promote pulmonary angiogenesis in HPS rats via ALK1-Endoglin-Smad1/5/9 pathway. In addition, BMP9-regulated pathways are also involved in accumulation of pro-angiogenic monocytes in the pulmonary microvasculature in HPS rats.

HDAC6 Enhances Endoglin Expression through Deacetylation of Transcription Factor SP1, Potentiating BMP9-Induced Angiogenesis

Histone deacetylase 6 (HDAC6) plays a crucial role in the acetylation of non-histone proteins and is notably implicated in angiogenesis, though its underlying mechanisms were previously not fully understood. This study conducted transcriptomic and proteomic analyses on vascular endothelial cells with HDAC6 knockdown, identifying endoglin (ENG) as a key downstream protein regulated by HDAC6. This protein is vital for maintaining vascular integrity and plays a complex role in angiogenesis, particularly in its interaction with bone morphogenetic protein 9 (BMP9). In experiments using human umbilical vein endothelial cells (HUVECs), the pro-angiogenic effects of BMP9 were observed, which diminished following the knockdown of HDAC6 and ENG. Western blot analysis revealed that BMP9 treatment increased SMAD1/5/9 phosphorylation, a process hindered by HDAC6 knockdown, correlating with reduced ENG expression. Mechanistically, our study indicates that HDAC6 modulates ENG transcription by influencing promoter activity, leading to increased acetylation of transcription factor SP1 and consequently altering its transcriptional activity. Additionally, the study delves into the structural role of HDAC6, particularly its CD2 domain, in regulating SP1 acetylation and subsequently ENG expression. In conclusion, the present study underscores the critical function of HDAC6 in modulating SP1 acetylation and ENG expression, thereby significantly affecting BMP9-mediated angiogenesis. This finding highlights the potential of HDAC6 as a therapeutic target in angiogenesis-related processes.

Fluid shear stress-modulated chromatin accessibility reveals the mechano-dependency of endothelial SMAD1/5-mediated gene transcription

Bone morphogenetic protein (BMP) signaling and fluid shear stress (FSS) mediate complementary functions in vascular homeostasis and disease development. It remains to be shown whether altered chromatin accessibility downstream of BMP and FSS offers a crosstalk level to explain changes in SMAD-dependent transcription. Here, we employed ATAC-seq to analyze arterial endothelial cells stimulated with BMP9 and/or FSS. We found that BMP9-sensitive regions harbor non-palindromic GC-rich SMAD-binding elements (GGCTCC) and 69.7% of these regions become BMP-insensitive in the presence of FSS. While GATA and KLF transcription factor (TF) motifs are unique to BMP9- and FSS-sensitive regions, respectively, SOX motifs are common to both. Finally, we show that both SOX(13/18) and GATA(2/3/6) family members are directly upregulated by SMAD1/5. These findings highlight the mechano-dependency of SMAD-signaling by a sequential mechanism of first elevated pioneer TF expression, allowing subsequent chromatin opening to eventually providing accessibility to novel SMAD binding sites.

Catalpol Prevents Glomerular Angiogenesis Induced by Advanced Glycation End Products via Inhibiting Galectin-3

OBJECTIVE

The main characteristics of diabetic nephropathy (DN) at the early stage are abnormal angiogenesis of glomerular endothelial cells (GECs) and macrophage infiltration. Galectin-3 plays a pivotal role in the pathogenesis of DN via binding with its ligand, advanced glycation end products (AGEs). Catalpol, an iridoid glucoside extracted from Rehmannia glutinosa, has been found to ameliorate vascular inflammation, reduce endothelial permeability, and protect against endothelial damage in diabetic milieu. However, little is known about whether catalpol could exert an anti-angiogenesis and anti-inflammation effect induced by AGEs.

METHODS

Mouse GECs (mGECs) and RAW 264.7 macrophages were treated with different concentrations of AGEs (0, 50, 100, 200 and 400 µg/mL) for different time (0, 6, 12, 24 and 48 h) to determine the optimal concentration of AGEs and treatment time. Cells were treated with catalpol (10 µmol/L), GB1107 (1 µmol/L, galectin-3 inhibitor), PX-478 (50 µmol/L, HIF-1α inhibitor), adenovirus-green fluorescent protein (Ad-GFP) [3×107 plaque-forming unit (PFU)/mL] or Ad-galectin-3-GFP (2×108 PFU/mL), which was followed by incubation with 50 µg/mL AGEs. The levels of galectin-3, vascular endothelial growth factor A (VEGFA) and pro-angiogenic factors angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), tunica interna endothelial cell kinase-2 (Tie-2) were detected by enzymelinked immunosorbent assay (ELISA). Cell counting kit-8 (CCK-8) assay was used to evaluate the proliferation of these cells. The expression levels of galectin-3, vascular endothelial growth factor receptor 1 (VEGFR1), VEGFR2, and hypoxia-inducible factor-1α (HIF-1α) in mGECs and those of galectin-3 and HIF-1α in RAW 264.7 macrophages were detected by Western blotting and immunofluorescence (IF) staining. The rat DN model was established. Catalpol (100 mg/kg) or GB1107 (10 mg/kg) was administered intragastrically once a day for 12 weeks. Ad-galectin-3-GFP (6×107 PFU/mL, 0.5 mL) or Ad-GFP (6×106 PFU/mL, 0.5 mL) was injected into the tail vein of rats 48 h before the sacrifice of the animals. The expression of galectin-3, VEGFR1, VEGFR2, and HIF-1α in renal cortices was analyzed by Western blotting. The expression of galectin-3, F4/80 (a macrophage biomarker), and CD34 (an endothelium biomarker) in renal cortices was detected by IF staining, and collagen accumulation by Masson staining.

RESULTS

The expression levels of galectin-3 and VEGFA were significantly higher in mGECs and RAW 264.7 macrophages treated with 50 µg/mL AGEs for 48 h than those in untreated cells. Catalpol and GB1107 could block the AGEs-induced proliferation of mGECs and RAW 264.7 macrophages. Over-expression of galectin-3 was found to reduce the inhibitory effect of catalpol on the proliferation of cells. Catalpol could significantly decrease the levels of Ang-1, Ang-2 and Tie-2 released by AGEs-treated mGECs, which could be reversed by over-expression of galectin-3. Catalpol could significantly inhibit AGEs-induced expression of galectin-3, HIF-1α, VEGFR1, and VEGFR2 in mGECs. The inhibitory effect of catalpol on galectin-3 in AGEs-treated mGECs was impaired by PX-478. Moreover, catalpol attenuated the AGEs-activated HIF-1α/galectin-3 pathway in RAW 264.7 macrophages, which was weakened by PX-478. Additionally, catalpol significantly inhibited the expression of galectin-3, macrophage infiltration, collagen accumulation, and angiogenesis in the kidney of diabetic rats. Over-expression of galectin-3 could antagonize these inhibitory effects of catalpol.

CONCLUSION

Catalpol prevented the angiogenesis of mGECs and macrophage proliferation via inhibiting galectin-3. It could prevent the progression of diabetes-induced renal damage.

Targeting SMYD2 inhibits angiogenesis and increases the efficiency of apatinib by suppressing EGFL7 in colorectal cancer

Angiogenesis is an essential factor affecting the occurrence and development of solid tumors. SET And MYND Domain Containing 2 (SMYD2) serves as an oncogene in various cancers. However, whether SMYD2 is involved in tumor angiogenesis remains unclear. Here, we report that SMYD2 expression is associated with microvessel density in colorectal cancer (CRC) tissues. SMYD2 promotes CRC angiogenesis in vitro and in vivo. Mechanistically, SMYD2 physically interacts with HNRNPK and mediates lysine monomethylation at K422 of HNRNPK, which substantially increases RNA binding activity. HNRNPK acts by binding and stabilizing EGFL7 mRNA. As an angiogenic stimulant, EGFL7 enhances CRC angiogenesis. H3K4me3 maintained by PHF8 mediates the abnormal overexpression of SMYD2 in CRC. Moreover, targeting SMYD2 blocks CRC angiogenesis in tumor xenografts. Treatment with BAY-598, a functional inhibitor of SMYD2, can also synergize with apatinib in patient-derived xenografts. Overall, our findings reveal a new regulatory axis of CRC angiogenesis and provide a potential strategy for antiangiogenic therapy.

EGFL7 Secreted By Human Bone Mesenchymal Stem Cells Promotes Osteoblast Differentiation Partly Via Downregulation Of Notch1-Hes1 Signaling Pathway

BACKGROUND

Epidermal growth factor-like domain protein 7 (EGFL7) is a secreted protein that is differentially expressed in the bone microenvironment; however, the effect of EGFL7 on the osteogenesis of human bone marrow mesenchymal stem cells (hBMSCs) is largely unknown.

METHODS

EGFL7 expression in the fracture microenvironment was analyzed based on the Gene Expression Omnibus (GEO) database. Knockdown of EGFL7 by small interfering RNA (siRNA) and in vitro stimulation with recombinant human EGFL7 (rhEGFL7) protein were used to assess alterations in downstream signaling and changes in the osteogenic differentiation and proliferation of hBMSCs. A γ-secretase inhibitor was used to further explore whether inhibition of Notch signaling rescued the osteogenic-inhibitory effect of EGFL7 knockdown in hBMSCs. A femoral defect model was established to verify the effect of recombinant mouse EGFL7 on bone healing in vivo.

RESULTS

EGFL7 expression increased during hBMSC osteogenesis. Knockdown of EGFL7 impaired hBMSC osteogenesis and activated Notch1/NICD/Hes1 signaling. rhEGFL7 promoted hBMSC osteogenesis and downregulated Notch1 signaling. The osteoblast-inhibitory effect of EGFL7 knockdown was rescued by Notch1 signaling inhibition. Recombinant EGFL7 led to enhanced bone healing in mice with femoral defects.

CONCLUSIONS

EGFL7 promotes osteogenesis of hBMSCs partly via downregulation of Notch1 signaling.

Analysis of scRNA-seq and bulk RNA-seq demonstrates the effects of EVI2B or CD361 on CD8+ T cells in osteosarcoma

Osteosarcoma (OS) is a common primary malignant tumor of the bone in children and adolescents. The five-year survival rate is estimated to be ~70% based on the currently available treatment modalities. It is well known that tumor-infiltrating immune cells (TIICs) that are the most important components in the tumor microenvironment can exert a killing effect on tumor cells. Therefore, in the present study, 85 RNA-sequencing OS samples were categorized into high- and low-immune score groups with ESTIAMATE. Based on the immune score groups, 474 differentially expressed genes (DEGs) were acquired using the LIMMA package of R language. Subsequently, 86 DEGs were taken through univariate COX regression analysis, of which 14 were screened out by least absolute shrinkage and selection operator regression analysis. Furthermore, multivariate COX regression analysis was performed to obtain 4 DEGs. Finally, ecotropic virus integration site 2B (EVI2B) or CD361 gene was screened out via Kaplan-Meier analysis. In addition, CIBERSORT algorithm was used to evaluate the proportion of 22 kinds of TIICs in OS. Correlation analysis revealed that the high expression level of EVI2B can elevate the infiltrated proportion of CD8⁺ T cells. Moreover, analysis of single cell RNA-sequencing transcriptome datasets and immunohistochemical staining uncovered that EVI2B was mainly expressed on CD8⁺ T cells and that EVI2B could promote the expression of granzyme A and K of CD8⁺ T cells to exhibit a potent killing effect on tumor cells. Therefore, EVI2B was identified as a protective immune-related gene and contributed to good prognosis in OS patients.

Single-cell atlas of murine adrenal glands reveals immune-adrenal crosstalk during systemic <i>Candida albicans</i> infection

Fungal sepsis remains a major health threat with high mortality, where the adrenal gland stress response has been rarely reported. <i>Candida albicans</i> (<i>C.albicans</i>) is the most common opportunistic fungal pathogen of life-threatening disseminated candidiasis and fungal sepsis. In the present study, we performed single-cell RNA sequencing (scRNA-Seq) using the 10x Genomics platform to analyze the changes in murine adrenal transcriptome following systemic <i>C.albicans</i> infection. A total of 16 021 cells were categorized into 18 transcriptionally distinct clusters, representing adrenocortical cells, endothelial cells, various immune cells, mesenchymal cells, smooth muscle cells, adrenal capsule, chromaffin cells, neurons and glials. As the main cell component in the adrenal gland responsible for steroidogenesis, the adrenocortical cells dramatically diminished and were further grouped into 10 subclusters, which differently distributed in the infected and uninfected samples. Pseudo-time analysis revealed transitions of the adrenocortical cells from the initial normal states to active or dysfunctional states following systemic <i>C.albicans</i> infection <i>via</i> two trajectory paths. Endothelial cells in the highly vascularized organ of adrenal gland further proliferated following infection, with the upregulation of genes positively regulating angiogenesis and downregulation of protective genes of endothelial cells. Immune cells were also excessively infiltrated in adrenal glands of <i>C.albicans</i>-infected mice. Macrophages dominated the immune microenvironments in murine adrenal glands both before and after <i>C.albicans</i> infection, mediating the crosstalk among the steroid-producing cells, endothelial cells and immune cells within the adrenal gland. NLR family, pyrin domain containing 3 (NLRP3, encoded by <i>Nlrp3</i>) and complement receptor 3 (CR3, encoded by <i>Itgam</i>) were found to be significantly upregulated on the adrenal macrophages upon systemic <i>C.albicans</i> infection and might play critical roles in mediating the myeloid response. Meanwhile, the number and strength of the interactions between the infiltrating immune cells and adrenal resident cells were unveiled by cell-cell communication analysis to be dramatically increased after systemic <i>C.albicans</i> infection, indicating that the immune-adrenal crosstalk might contribute to the compromised functions of adrenal cells. Overall, our comprehensive picture of the murine adrenal gland microenvironment in systemic <i>C.albicans</i> infection provides deeper insights into the immune-adrenal cell communications during fungal sepsis.

EGFL7 expression profile in IDH-wildtype glioblastomas is associated with poor patient outcome

Background

Despite the advances in glioblastoma (GBM) treatment, the average life span of patients is 14 months. Therefore, it is urgent to identity biomarkers of prognosis, treatment response, or development of novel treatment strategies. We previously described the association of high epidermal growth factor-like domain multiple 7 (EGFL7) expression and unfavorable outcome of pilocytic astrocytoma patients. The present study aims to analyze the prognostic potential of EGFL7 in GBM isocitrate dehydrogenase (IDH)-wildtype, using immunohistochemistry and in silico approaches.

Materials and Methods

Spearman's correlation analysis of The Cancer Genome Atlas RNA sequencing data was performed. The genes strongly correlated to EGFL7 expression were submitted to enrichment gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Additionally, EGFL7 expression was associated with patient overall survival. The expression of EGFL7 was analyzed through immunohistochemistry in 74 GBM IDH-wildtype patients' samples, and was associated with clinicopathological data and overall survival.

Results

In silico analysis found 78 genes strongly correlated to EGFL7 expression. These genes were enriched in 40 biological processes and eight KEGG pathways, including angiogenesis/vasculogenesis, cell adhesion, and phosphoinositide 3-kinase-Akt, Notch, and Rap1 signaling pathways. The immunostaining showed high EGFL7 expression in 39 cases (52.7%). High immunolabelling was significantly associated with low Karnofsky Performance Status and poor overall survival. Cox analysis showed that GBMs IDH-wildtype with high EGFL7 expression presented a higher risk of death compared to low expression (hazard ratio, 1.645; 95% confidence interval, 1.021 to 2.650; p = .041).

Conclusion

This study gives insights regarding the genes that are correlated with EGFL7, as well as biological processes and signaling pathways, which should be further investigated in order to elucidate their role in glioblastoma biology.

Stem Cell-Mediated Angiogenesis in Skin Tissue Engineering and Wound Healing

The timely management of skin wounds has been an unmet clinical need for centuries. While there have been several attempts to accelerate wound healing and reduce the cost of hospitalisation and the healthcare burden, there remains a lack of efficient and effective wound healing approaches. In this regard, stem cell‐based therapies have garnered an outstanding position for the treatment of both acute and chronic skin wounds. Stem cells of different origins (e.g., embryo‐derived stem cells) have been utilised for managing cutaneous lesions; specifically, mesenchymal stem cells (MSCs) isolated from foetal (umbilical cord) and adult (bone marrow) tissues paved the way to more satisfactory outcomes. Since angiogenesis plays a critical role in all four stages of normal wound healing, recent therapeutic approaches have focused on utilising stem cells for inducing neovascularisation. In fact, stem cells can promote angiogenesis via either differentiation into endothelial lineages or secreting pro‐angiogenic exosomes. Furthermore, particular conditions (e.g., hypoxic environments) can be applied in order to boost the pro‐angiogenic capability of stem cells before transplantation. For tissue engineering and regenerative medicine applications, stem cells can be combined with specific types of pro‐angiogenic biocompatible materials (e.g., bioactive glasses) to enhance the neovascularisation process and subsequently accelerate wound healing. As such, this review article summarises such efforts emphasising the bright future that is conceivable when using pro‐angiogenic stem cells for treating acute and chronic skin wounds.

ATG16L1 is a Potential Prognostic Biomarker and Immune Signature for Osteosarcoma: A Study Based on Bulk RNA and Single-Cell RNA-Sequencing

Background

Osteosarcoma is a common solid malignancy of the bone in children and adolescents, and its metastasis and recurrence are the principal causes of poor treatment outcomes.

Methods

Autophagy-related genes were used to cluster osteosarcoma patients by consensus clustering analysis using the GSE21257 database. Differentially expressed genes (DEGs) were identified by limma package. Multiple-gene risk signature was constructed using least absolute shrinkage and selection operator (LASSO) analysis and Cox regression analyses. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to determine gene expression levels. Then, single-cell RNA-sequencing dataset GSE152048 were used to identify the correlation between the DEGs and effector molecules expressed in specific tumor-infiltrating immune cells.

Results

Two clusters were identified in the consensus clustering analysis, which were confirmed by principal component analysis. Limma analysis revealed that 15 genes were related, and 9 genes were screened using protein-protein interaction network and LASSO regression analysis. Cox regression analyses identified 5 genes. Combined with survival analysis, only the autophagy related 16 like 1 gene (ATG16L1) was significant. The results of qRT-PCR showed low expression levels of ATG16L1 in tumor cells group. Immune infiltration analysis revealed significantly lower expression of CD8⁺ T cells in the high ATG16L1 gene expression group. ScRNA-seq revealed that in the ATG16L1⁺CD8⁺ T cell group, the expression of GZMB was lower, whereas the expression of ITGA1 was higher. These results showed that ATG16L1 is an immune-related gene, which is associated with poor prognosis in patients with osteosarcoma.

Conclusion

ATG16L1 is a potential prognostic biomarker and immune signature and may be a therapeutic target for osteosarcoma.

Rethinking growth factors: the case of BMP9 during vessel maturation

Angiogenesis is an essential process for correct development and physiology. This mechanism is tightly regulated by many signals that activate several pathways, which are constantly interacting with each other. There is mounting evidence that BMP9/ALK1 pathway is essential for a correct vessel maturation. Alterations in this pathway lead to the development of hereditary haemorrhagic telangiectasias. However, little was known about the BMP9 signalling cascade until the last years. Recent reports have shown that while BMP9 arrests cell cycle, it promotes the activation of anabolic pathways to enhance endothelial maturation. In light of this evidence, a new criterion for the classification of cytokines is proposed here, based on the physiological objective of the activation of anabolic routes. Whether this activation by a growth factor is needed to sustain mitosis or to promote a specific function such as matrix formation is a critical characteristic that needs to be considered to classify growth factors. Hence, the state-of-the-art of BMP9/ALK1 signalling is reviewed here, as well as its implications in normal and pathogenic angiogenesis.

The biology of bone morphogenetic protein signaling pathway in cerebrovascular system

Bone morphogenetic protein belongs to transcription growth factor superfamily β; bone morphogenetic protein signal pathway regulates cell proliferation, differentiation, and apoptosis among different tissues. Cerebrovascular system supplies sufficient oxygen and blood into brain to maintain its normal function. The disorder of cerebrovascular system will result into serious cerebrovascular diseases, which is gradually becoming a major threat to human health in modern society. In recent decades, many studies have revealed the underlying biology and mechanism of bone morphogenetic protein signal pathway played in cerebrovascular system. This review will discuss the relationship between the two aspects, aiming to provide new perspective for non-invasive treatment and basic research of cerebrovascular diseases.

BMP9 and BMP10: two close vascular quiescence partners that stand out

Bone morphogenetic proteins (BMPs) are dimeric transforming growth factor ß (TGFß) family cytokines that were first described in bone and cartilage formation but have since been shown to be involved in many pleiotropic functions. In human, there are 15 BMP ligands, which initiate their cellular signaling by forming a complex with two copies of type I receptors and two copies of type II receptors, both of which are transmembrane receptors with an intracellular serine/threonine kinase domain. Within this receptor family, ALK1 (Activin receptor-Like Kinase 1), which is a type I receptor mainly expressed on endothelial cells, and BMPRII (BMP Receptor type II), a type II receptor also highly expressed on endothelial cells, have been directly linked to two rare vascular diseases: hereditary haemorrhagic telangiectasia (HHT), and pulmonary arterial hypertension (PAH), respectively. BMP9 (gene name GDF2) and BMP10, two close members of the BMP family, are the only known ligands for the ALK1 receptor. This specificity gives them a unique role in physiological and pathological angiogenesis and tissue homeostasis. The aim of this current review is to present an overview of what is known about BMP9 and BMP10 on vascular regulation with a particular emphasis on recent results and the many questions that remain unanswered regarding the roles and specificities between BMP9 and BMP10. This article is protected by copyright. All rights reserved.

The BMP Pathway in Blood Vessel and Lymphatic Vessel Biology

Bone morphogenetic proteins (BMPs) were originally identified as the active components in bone extracts that can induce ectopic bone formation. In recent decades, their key role has broadly expanded beyond bone physiology and pathology. Nowadays, the BMP pathway is considered an important player in vascular signaling. Indeed, mutations in genes encoding different components of the BMP pathway cause various severe vascular diseases. Their signaling contributes to the morphological, functional and molecular heterogeneity among endothelial cells in different vessel types such as arteries, veins, lymphatic vessels and capillaries within different organs. The BMP pathway is a remarkably fine-tuned pathway. As a result, its signaling output in the vessel wall critically depends on the cellular context, which includes flow hemodynamics, interplay with other vascular signaling cascades and the interaction of endothelial cells with peri-endothelial cells and the surrounding matrix. In this review, the emerging role of BMP signaling in lymphatic vessel biology will be highlighted within the framework of BMP signaling in the circulatory vasculature.

Stem cell-based therapies for cardiac diseases: The critical role of angiogenic exosomes

Finding effective treatments for cardiac diseases is among the hottest subjects in medicine; cell-based therapies have brought great promises for managing a broad range of life-threatening heart complications such as myocardial infarction. After clarifying the critical role of angiogenesis in tissue repair and regeneration, various stem/progenitor cell were utilized to accelerate the healing of injured cardiac tissue. Embryonic, fetal, adult, and induced pluripotent stem cells have shown the appropriate proangiogenic potential for tissue repair strategies. The capability of stem cells for differentiating into endothelial lineages was initially introduced as the primary mechanism involved in improving angiogenesis and accelerated heart tissue repair. However, recent studies have demonstrated the leading role of paracrine factors secreted by stem cells in advancing neo-vessel formation. Genetically modified stem cells are also being applied for promoting angiogenesis regarding their ability to considerably overexpress and secrete angiogenic bioactive molecules. Yet, conducting further research seems necessary to precisely identify molecular mechanisms behind the proangiogenic potential of stem cells, including the signaling pathways and regulatory molecules such as microRNAs. In conclusion, stem cells' pivotal roles in promoting angiogenesis and consequent improved cardiac healing and remodeling processes should not be ignored, especially in the case of stem cell-derived extracellular vesicles.

Epidermal growth factor-like domain 7 regulates breast cancer cell proliferation and vascular endothelial growth factor expression via the p38MAPK signaling pathway

OBJECTIVE

We aimed to investigate the effects of epidermal growth factor-like domain 7 (EGFL7) on breast cancer cell proliferation and angiogenesis and its association with the p38 mitogen-activated protein kinase (p38MAPK) signaling pathway.

METHODS

The vectors for stable overexpression of EGFL7 and the vectors for EGFL7 knockout were constructed. The breast cancer cell line MDA-MB-231 was selected for this study and the cells were divided into four groups: the control group, the empty vector group (transfected with an empty vector), the EGFL7 overexpression group (transfected with the EGFL7 overexpression vector), and the EGFL7 knockout group (transfected with the EGFL7 knockout vector). After 72 h of transfection, the mRNA and protein levels of EGFL7 in the cells were detected by RT-PCR and Western blot, respectively. The cell proliferation rates at 12 h, 24 h, 48 h and 72 h of culture in each group were detected using the MTT method. An in vitro tumor angiogenesis model of tumor-endothelial cells co-culture system was established and the angiogenesis ability at 12 h, 24 h, 48 h and 72 h of culture were compared among the groups using an in vitro angiogenesis assay. The cells in the EGFL7 overexpression group were further divided into three groups and were treated with p38MAPK inhibitor SB203580 at a dose of 0 μmol/L, 5 μmol/L, and 10 μmol/L, respectively. Afterward, the cells were co-cultured with endothelial cells for 48 h. Western blot was performed to detect the protein levels of vascular endothelial growth factor (VEGF), p38MAPK, and p-p38MAPK.

RESULTS

Compared with the control group, the EGFL7 mRNA level was higher in the EGFL7 overexpression group and lower in the EGFL7 knockout group (both P<0.05). Compared with the control group at 12 h, 24 h, 48 h, and 72 h of culture, the cell proliferation rates were lower in the EGFL knockout group and higher in the EGFL overexpression group, respectively (all P<0.05). Moreover, compared with the control group at these time points, the number of vascular sprouts and the protein levels of VEGF, p38MAPK, and p-p38MAPK were lower in the EGFL7 knockout group and higher in the EGFL7 overexpression group, respectively (all P<0.05). After the cells overexpressing EGFL7 were treated with SB203580, the level of p-p38MAPK was deceased, and the protein expression level of VEGF was inversely related with the SB203580 concentration (F=44.24, P<0.01).

CONCLUSION

EGFL7 can promote the proliferation of breast cancer cells and angiogenesis, and the mechanism may be associated with the activation of p38MAPK signaling pathway and promotion of VEGF expression.

The Multifaceted Roles of EGFL7 in Cancer and Drug Resistance

Simple Summary

Cancer growth and metastasis require interactions with the extracellular matrix (ECM), which is home to many biomolecules that support the formation of new vessels and cancer growth. One of these biomolecules is epidermal growth factor-like protein-7 (EGFL7). EGFL7 alters cellular adhesion to the ECM and migratory behavior of tumor and immune cells contributing to tumor metastasis. EGFL7 is engaged in the formation of new vessels and changes in ECM stiffness. One of its binding partners on the endothelial and cancer cell surface is beta 3 integrin. Beta 3 integrin pathways are under intense investigation in search of new therapies to kill cancer cells. All these properties enable EGFL7 to contribute to drug resistance. In this review, we give insight into recent studies on EGFL7 and its engagement with beta3 integrin, a marker predicting cancer stem cells and drug resistance.

Abstract

Invasion of cancer cells into surrounding tissue and the vasculature is an important step for tumor progression and the establishment of distant metastasis. The extracellular matrix (ECM) is home to many biomolecules that support new vessel formation and cancer growth. Endothelial cells release growth factors such as epidermal growth factor-like protein-7 (EGFL7), which contributes to the formation of the tumor vasculature. The signaling axis formed by EGFL7 and one of its receptors, beta 3 integrin, has emerged as a key mediator in the regulation of tumor metastasis and drug resistance. Here we summarize recent studies on the role of the ECM-linked angiocrine factor EGFL7 in primary tumor growth, neoangiogenesis, tumor metastasis by enhancing epithelial-mesenchymal transition, alterations in ECM rigidity, and drug resistance. We discuss its role in cellular adhesion and migration, vascular leakiness, and the anti-cancer response and provide background on its transcriptional regulation. Finally, we discuss its potential as a drug target as an anti-cancer strategy.

EGFL7 as a novel therapeutic candidate regulates cell invasion and anoikis in colorectal cancer through PI3K/AKT signaling pathway

BACKGROUND

Anoikis is a form of apoptosis, which inhibits metastatic cascade and deprives cancer cells with invasive capacity. Epidermal growth factor-like domain-containing protein 7 (EGFL7) is overexpressed in colorectal cancer (CRC) and is a potential biomarker for malignancy. The present study aimed was to investigate the effect and underlying mechanism of EGFL7 on CRC cell function.

METHODS

EGFL7 expression in mutable human CRC cell lines and normal intestinal epithelial cell line HIEC were measured by qRT-PCR. To investigate the biological functions of EGFL7, loss-of-function experiments were performed by transfecting EGFL7 siRNA into SW620 and LoVo cells. Western blot analysis, MTT, invasion and anoikis assay were used to explore the underlying mechanism of EGFL7.

RESULTS

EGFL7 was upregulated in several CRC cell lines as compared with normal intestinal epithelial cell line HIEC. Transfection of EGFL7 siRNA significantly decreased cell proliferation and invasion capacity of SW620 and LoVo cells. Additionally, EGFL7 inhibition markedly elevated anoikis through modulating anoikis marker proteins as reflected by increasing of cleaved-caspase-3 and cleaved-PAPR expression. Moreover, downregulation of EGFL7 inhibited PI3K and P-AKT expression. Furthermore, re-expression of PI3K remarkably reversed the effects of EGFL7 on SW620 cells.

CONCLUSION

Overall, our findings suggested that EGFL7 acts as an oncogene, regulated CRC invasion and anoikis through PI3K/AKT signaling, which provided a theoretical basis for EGFL7 as a potential therapeutic target of CRC treatment.

Evaluation of the prognostic potential of EGFL7 in pilocytic astrocytomas

Pilocytic astrocytoma (PA) is the most frequent solid neoplasm in childhood. It has a good 5-year overall survival (90% in childhood and 52% in adults). However, up to 20% of patients experience residual tumor growth, recurrence, and death. Although the main genetic alteration of PAs, including KIAA1549:BRAF fusion, involves chromosome 7q34, we previously found frequent loss in chr9q34.3 locus in a small subset of these tumors. Among the genes present in this locus, EGFL7 is related to poor prognosis in several tumor types. In this study, we aimed to assess EGFL7 expression through immunohistochemistry, and to evaluate its prognostic value in a series of 64 clinically and molecularly well-characterized pilocytic astrocytomas. We found high expression of EGFL7 in 71.9% of patients. Low EGFL7 expression was associated with older patients, the mean age mainly older than 11 years (P = 0.027). EGFL7 expression was not associated with presence of KIAA1549:BRAF fusion, BRAF mutation, FGFR1 mutation, nor FGFR1 duplication. Moreover, high EGFL7 expression was associated with high FGFR1 (P = 0.037) and 5'-deoxy-5'-methyltioadenosine phosphorylase (MTAP) (P = 0.005) expression, and with unfavorable outcome of patients (P = 0.047). Multivariate analysis revealed low EGFL7 expression related to older patients and high EGFL7 expression related to retained expression of MTAP. In addition, we found a borderline significance of unfavorable outcome and high EGFL7 expression. Finally, EGFL7 expression was not associated with overall or event-free survival of PA patients. Our findings point to EGFL7 expression as a novel candidate prognostic marker in PA, which should be further investigated.

It Takes Two to Tango: Endothelial TGFβ/BMP Signaling Crosstalk with Mechanobiology

Bone morphogenetic proteins (BMPs) are members of the transforming growth factor-beta (TGFβ) superfamily of cytokines. While some ligand members are potent inducers of angiogenesis, others promote vascular homeostasis. However, the precise understanding of the molecular mechanisms underlying these functions is still a growing research field. In bone, the tissue in which BMPs were first discovered, crosstalk of TGFβ/BMP signaling with mechanobiology is well understood. Likewise, the endothelium represents a tissue that is constantly exposed to multiple mechanical triggers, such as wall shear stress, elicited by blood flow or strain, and tension from the surrounding cells and to the extracellular matrix. To integrate mechanical stimuli, the cytoskeleton plays a pivotal role in the transduction of these forces in endothelial cells. Importantly, mechanical forces integrate on several levels of the TGFβ/BMP pathway, such as receptors and SMADs, but also global cell-architecture and nuclear chromatin re-organization. Here, we summarize the current literature on crosstalk mechanisms between biochemical cues elicited by TGFβ/BMP growth factors and mechanical cues, as shear stress or matrix stiffness that collectively orchestrate endothelial function. We focus on the different subcellular compartments in which the forces are sensed and integrated into the TGFβ/BMP growth factor signaling.

BMP9 is a potential therapeutic agent for use in oral and maxillofacial bone tissue engineering

Oral and maxillofacial surgery is often challenging due to defective bone healing owing to the microbial environment of the oral cavity, the additional involvement of teeth and esthetic concerns. Insufficient bone volume as a consequence of aging and some oral and maxillofacial surgical procedures, such as tumor resection of the jaw, may further impact facial esthetics and cause the failure of certain procedures, such as oral and maxillofacial implantation. Bone morphogenetic protein (BMP) 9 (BMP9) is one of the most effective BMPs to induce the osteogenic differentiation of different stem cells. A large cross-talk network that includes the BMP9, Wnt/β, Hedgehog, EGF, TGF-β and Notch signaling pathways finely regulates osteogenesis induced by BMP9. Epigenetic control during BMP9-induced osteogenesis is mainly dependent on histone deacetylases (HDACs), microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), which adds another layer of complexity. As a result, all these factors work together to orchestrate the molecular and cellular events underlying BMP9-related tissue engineering. In this review, we summarize our current understanding of the SMAD-dependent and SMAD-independent BMP9 pathways, with a particular focus on cross-talk and cross-regulation between BMP9 and other major signaling pathways in BMP9-induced osteogenesis. Furthermore, recently discovered epigenetic regulation of BMP9 pathways and the molecular and cellular basis of the application of BMP9 in tissue engineering in current oral and maxillofacial surgery and other orthopedic-related clinical settings are also discussed.

Saliva exosomes-derived UBE2O mRNA promotes angiogenesis in cutaneous wounds by targeting SMAD6

Background

Enhancing angiogenesis is critical for accelerating wound healing. Application of different types of exosomes (Exos) to promote angiogenesis represents a novel strategy for enhanced wound repair. Saliva is known to accelerate wound healing, but the underlying mechanisms remain unclear.

Results

Our results have demonstrated that saliva-derived exosomes (saliva-Exos) induce human umbilical vein endothelial cells (HUVEC) proliferation, migration, and angiogenesis in vitro, and promote cutaneous wound healing in vivo. Further experiments documented that Ubiquitin-conjugating enzyme E2O (UBE2O) is one of the main mRNAs of saliva-Exos, and activation of UBE2O has effects similar to those of saliva-Exos, both in vitro and in vivo. Mechanistically, UBE2O decreases the level of SMAD family member 6 (SMAD6), thereby activating bone morphogenetic protein 2 (BMP2), which, in turn, induces angiogenesis.

Conclusions

The present work suggests that administration of saliva-Exos and UBE2O represents a promising strategy for enhancing wound healing through promotion of angiogenesis.

The TGFβ Family in Human Placental Development at the Fetal-Maternal Interface

Emerging data suggest that a trophoblast stem cell (TSC) population exists in the early human placenta. However, in vitro stem cell culture models are still in development and it remains under debate how well they reflect primary trophoblast (TB) cells. The absence of robust protocols to generate TSCs from humans has resulted in limited knowledge of the molecular mechanisms that regulate human placental development and TB lineage specification when compared to other human embryonic stem cells (hESCs). As placentation in mouse and human differ considerably, it is only with the development of human-based disease models using TSCs that we will be able to understand the various diseases caused by abnormal placentation in humans, such as preeclampsia. In this review, we summarize the knowledge on normal human placental development, the placental disease preeclampsia, and current stem cell model systems used to mimic TB differentiation. A special focus is given to the transforming growth factor-beta (TGFβ) family as it has been shown that the TGFβ family has an important role in human placental development and disease.

Tetrandrine inhibits proliferation of colon cancer cells by BMP9/ PTEN/ PI3K/AKT signaling

Despite advances in screening and treatment, colon cancer remains one of the leading causes of cancer-related death. Finding novel and useful drug treatment targets is also an urgent need for clinical applications. Tetrandrine (Tet) is extracted from the Chinese medicinal herbal medicine, which is a well-known calcium blocker with a variety of pharmacological activities, including anti-cancer. In this study, we recruited cell viability assay, flow cytometry analysis, cloning formation to confirm that Tet can inhibit the proliferation of SW620 cells, and induce apoptosis. Mechanically, we confirmed that Tet up-regulates the mRNA and protein level of BMP9 in SW620 cells. Over-expression BMP9 enhances the anti-cancer effects of Tet in SW620 cells, but these effects can be partly reversed by silencing BMP9. Also, Tet reduces phosphorylation of Aktl/2/3 in SW620 cells, which could be elevated by overexpressed BMP9 and impaired by silencing BMP9. Furthermore, we demonstrated that Tet reduces phosphorylated PTEN, which can be promoted by overexpressed BMP9, analogously also be attenuated through silencing BMP9. Finally, we introduced a xenograft tumor model to investigate the anti-proliferative effect of Tet, further to explore the effects of BMP9 and PTEN in SW620 cells. Our findings suggested that the anti-cancer activity of Tet in SW620 cells may be mediated partly by up-regulating BMP9, followed by inactivation PI3K/Akt through up-regulating PTEN at least.