JNK signaling pathway is required for bFGF-mediated surface cadherin downregulation on HUVEC

Effect of SARS-CoV-2 proteins on vascular permeability

Severe acute respiratory syndrome (SARS)-CoV-2 infection leads to severe disease associated with cytokine storm, vascular dysfunction, coagulation, and progressive lung damage. It affects several vital organs, seemingly through a pathological effect on endothelial cells. The SARS-CoV-2 genome encodes 29 proteins, whose contribution to the disease manifestations, and especially endothelial complications, is unknown. We cloned and expressed 26 of these proteins in human cells and characterized the endothelial response to overexpression of each, individually. Whereas most proteins induced significant changes in endothelial permeability, nsp2, nsp5_c145a (catalytic dead mutant of nsp5), and nsp7 also reduced CD31, and increased von Willebrand factor expression and IL-6, suggesting endothelial dysfunction. Using propagation-based analysis of a protein–protein interaction (PPI) network, we predicted the endothelial proteins affected by the viral proteins that potentially mediate these effects. We further applied our PPI model to identify the role of each SARS-CoV-2 protein in other tissues affected by coronavirus disease (COVID-19). While validating the PPI network model, we found that the tight junction (TJ) proteins cadherin-5, ZO-1, and β-catenin are affected by nsp2, nsp5_c145a, and nsp7 consistent with the model prediction. Overall, this work identifies the SARS-CoV-2 proteins that might be most detrimental in terms of endothelial dysfunction, thereby shedding light on vascular aspects of COVID-19.

Evaluation of human umbilical vein endothelial cells growth onto heparin-modified electrospun vascular grafts

One of the main challenges of cardiovascular tissue engineering is the development of bioresorbable and compliant small-diameter vascular grafts (SDVG) for patients where autologous grafts are not an option. In this work, electrospun bilayered bioresorbable SDVG based on blends of poly(L-lactic acid) (PLLA) and segmented polyurethane (PHD) were prepared and evaluated. The inner layer of these SDVG was surface-modified with heparin, following a methodology involving PHD urethane functional groups. Heparin was selected as anticoagulant agent, and also due to its ability to promote human umbilical vein endothelial cells (HUVECs) growth and to inhibit smooth muscle cells over-proliferation, main cause of neointimal hyperplasia and restenosis. Immobilized heparin was quantified and changes in SDVG microstructure were investigated through SEM. Tensile properties of the heparin-functionalized SDVG resembled those of saphenous vein. Vascular grafts were seeded with HUVECs and cultured on a flow-perfusion bioreactor to analyze the effect of heparin on graft endothelization under simulated physiological-like conditions. The analysis of endothelial cells attachment and gene expression (Real-Time PCR) pointed out that the surface functionalization with heparin successfully promoted a stable and functional endothelial cell layer.

Antitumor effect of a short peptide on p53-null SKOV3 ovarian cancer cells

Fibroblast growth factor-2 (FGF2) is a protein ligand, which exerts essential roles in development, angiogenesis, and tumor progression via activation of the downstream signaling cascades. Accumulating evidence has demonstrated that FGF2 is involved in the progression of ovarian cancer, providing a novel potential target for ovarian cancer therapy. In this study, we showed that FGF2 is significantly increased in ovarian tumors, and is negatively associated with the overall survival of ovarian cancer by database analysis. A short peptide obtained from a heptapeptide phage display library suppressed FGF2-induced proliferation, migration, and invasion of the p53-null epithelial ovarian cancer (EOC) cells. Further investigations revealed that the short peptide antagonized the effects of FGF2 on G0/G1 to S cell phase promotion, cyclin D1 expression, and MAPK and Akt signaling activation, which might contribute to the mechanism underlying the inhibitory effects of the short peptide on the aggressive phenotype of the ovarian cancer cells triggered by FGF2. Moreover, the short peptide might have the potentials of reversing FGF2-induced resistance to the doxorubicin via downregulation of the antiapoptotic proteins and counteracting of the antiapoptotic effects of FGF2 on p53-null EOC cells. Taken together, the short peptide targeting FGF2 may provide a novel strategy for improving the therapeutic efficiency in a subset of EOC.

[TRPV4 regulates vascular endothelial permeability during colonic inflammation in dextran sulphate sodium-induced murine colitis]

The transient receptor potential vanilloid 4 (TRPV4) is a nonselective cation channel involved in physical sensing in various tissue types. The present study aimed to elucidate the function and expression of TRPV4 in colonic vascular endothelial cells during dextran sulphate sodium (DSS)-induced colitis. The role of TRPV4 in the progression of colonic inflammation was examined in the 2% DSS-induced murine colitis model using immunohistochemical analysis, Western blotting, and Evans blue dye extrusion assay. DSS-induced colitis was significantly attenuated in TRPV4-deficient (TRPV4 KO) mice when compared to wild-type mice. Repeated intrarectal administration of GSK1016790A, a TRPV4 agonist, exacerbated the severity of DSS-induced colitis. Bone marrow transfer experiments demonstrated a dominant role of TRPV4 in non-haematopoietic cells for DSS-induced colitis. DSS treatment upregulated TRPV4 expression in the vascular endothelia of colonic mucosa and submucosa. DSS treatment increased vascular permeability, which was abolished in TRPV4 KO mice. The DSS-induced increase in vascular permeability was further enhanced by intravenous administration of GSK1016790A, which was abrogated by a TRPV4 antagonist RN1734. TRPV4 was co-localized with vascular endothelial (VE)-cadherin, and VE-cadherin expression was decreased by repeated intravenous administration of GSK1016790A during colitis. Furthermore, TRPV4 activation by GSK106790A decreased VE-cadherin expression in mouse aortic endothelial cells exposed to TNF-α. These findings indicate that TRPV4 upregulation in vascular endothelial cells contributes to the progression of colonic inflammation via the activation of vascular permeability. Thus, TRPV4 is an attractive target for the treatment of inflammatory bowel diseases.

Transient receptor potential vanilloid 4 channel regulates vascular endothelial permeability during colonic inflammation in dextran sulphate sodium-induced murine colitis

BACKGROUND AND PURPOSE

The transient receptor potential vanilloid 4 (TRPV4) channel is a non-selective cation channel involved in physical sensing in various tissue types. The present study aimed to elucidate the function and expression of TRPV4 channels in colonic vascular endothelial cells during dextran sulphate sodium (DSS)-induced colitis.

EXPERIMENTAL APPROACH

The role of TRPV4 channels in the progression of colonic inflammation was examined in a murine DSS-induced colitis model using immunohistochemical analysis, Western blotting and Evans blue dye extrusion assay.

KEY RESULTS

DSS-induced colitis was significantly attenuated in TRPV4-deficient (TRPV4 KO) as compared to wild-type mice. Repeated intrarectal administration of GSK1016790A, a TRPV4 agonist, exacerbated the severity of DSS-induced colitis. Bone marrow transfer experiments demonstrated the important role of TRPV4 in non-haematopoietic cells for DSS-induced colitis. DSS treatment up-regulated TRPV4 expression in the vascular endothelia of colonic mucosa and submucosa. DSS treatment increased vascular permeability, which was abolished in TRPV4 KO mice. This DSS-induced increase in vascular permeability was further enhanced by i.v. administration of GSK1016790A, and this effect was abolished by the TRPV4 antagonist RN1734. TRPV4 was co-localized with vascular endothelial (VE)-cadherin, and VE-cadherin expression was decreased by repeated i.v. administration of GSK1016790A during colitis. Furthermore, GSK106790A decreased VE-cadherin expression in mouse aortic endothelial cells exposed to TNF-α.

CONCLUSION AND IMPLICATIONS

These findings indicate that an up-regulation of TRPV4 channels in vascular endothelial cells contributes to the progression of colonic inflammation by increasing vascular permeability. Thus, TRPV4 is an attractive target for the treatment of inflammatory bowel diseases.

EphrinB-mediated reverse signalling controls junctional integrity and pro-inflammatory differentiation of endothelial cells

The EphB/ephrinB receptor-ligand system is pivotal for the development of the embryonic vasculature and for angiogenesis in the adult organism. We observed that (i) the expression of ephrinB2 and ephrinB1 is up-regulated in capillaries during inflammation, that (ii) these ligands are localised on the luminal endothelial surface, and that (iii) they interact with the ephrinB-receptor EphB2 on monocyte/macrophages. This study delineates the impact of ephrinB-mediated reverse signalling on the integrity and proinflammatory differentiation of the endothelium. To this end, in vitro analyses with human cultured endothelial cells reveal that knockdown of ephrinB2 or ephrinB1 impairs monocyte transmigration through the endothelium. While ephrinB2 but not ephrinB1 interacts with PECAM-1 (CD31) in this context, reverse signalling by ephrinB1 but not ephrinB2 elicits a c-Jun N-terminal kinase (JNK)-dependent up-regulation of E-selectin expression. Furthermore, treatment of endothelial cells with soluble EphB2 receptor bodies or EphB2-overexpressing mouse myeloma cells links ephrinB2 to PECAM-1 and induces its Src-dependent phosphorylation while diminishing Src homology phosphotyrosyl phosphatase-2 (SHP-2) activity and increasing endothelial cell permeability. We conclude that extravasation of EphB2 positive leukocyte populations is facilitated by lowering the integrity of endothelial cell junctions and enhancing the pro-inflammatory phenotype of the endothelium through activation of ephrinB ligands.

p38 MAPK pathway is essential for self-renewal of mouse male germline stem cells (mGSCs)

OBJECTIVES

Male germline stem cells (mGSCs), also called spermatogonial stem cells (SSCs), constantly generate spermatozoa in male animals. A number of preliminary studies on mechanisms of mGSC self-renewal have previously been conducted, revealing that several factors are involved in this regulated process. The p38 MAPK pathway is widely conserved in multiple cell types in vivo, and plays an important role in cell proliferation, differentiation, inflammation and apoptosis. However, its role in self-renewal of mGSCs has not hitherto been determined.

MATERIALS AND METHODS

Here, the mouse mGSCs were cultured and their identity was verified by semi-RT-PCR, alkaline phosphatase (AP) staining and immunofluorescence staining. Then, the p38 MAPK pathway was blocked by p38 MAPK-specific inhibitor SB202190. mGSC self-renewal ability was then analysed by observation of morphology, cell number, cell growth analysis, TUNEL incorporation assay and cell cycle analysis.

RESULTS

Results showed that mouse mGSC self-renewal ability was significantly inhibited by SB202190.

CONCLUSIONS

This study showed for the first time that the p38 MAPK pathway plays a key role in maintaining self-renewal capacity of mouse mGSCs, which offers a new self-renewal pathway for these cells and contributes to overall knowledge of the mechanisms of mGSC self-renewal.

Adrenomedullin Up-regulates the Expression of Vascular Endothelial Growth Factor in Epithelial Ovarian Carcinoma Cells via JNK/AP-1 Pathway

OBJECTIVE

Adrenomedullin (AM), a potent vasodilator peptide, presents in various kinds of tumors and promotes angiogenesis. We have previously reported that AM is expressed in epithelial ovarian carcinoma tissue. Here, we investigated the hypothesis that AM might regulate production of vascular endothelial growth factor (VEGF) in epithelial ovarian carcinoma and further promote angiogenic processes.

METHODS

The messenger RNA expression of VEGF in human epithelial ovarian carcinoma cells (HO-8910) was examined by real-time polymerase chain reaction. Transcriptional control was analyzed by transient transfection assay of VEGF promoter-luciferase hybrid genes and chromatin immunoprecipitation assay. Activation of c-Jun N-terminal kinase (JNK) was detected by Western blotting. The formation of capillarylike structures by EA.hy926 cells cocultured with HO-8910 cells on Matrigel was also studied.

RESULTS

We found that in HO-8910 cells, AM (10⁻¹⁰ to 10⁻⁷ mol/L) enhanced VEGF messenger RNA expression in a time- and concentration-dependent manner, as well as promoter activity. Furthermore, JNK was activated by AM stimulation. The AM-induced increase in VEGF expression was significantly attenuated by SP600125, a specific JNK inhibitor. Chromatin immunoprecipitation assay and promoter activity analysis showed that VEGF expression induced by AM required the activator protein 1 motif on the VEGF promoter. In an in vitro angiogenesis system for endothelial cells (EA.hy926) cocultured with HO-8910 cells, we observed that the addition of AM stimulated endothelial cell tube formation, which could be abolished by VEGF neutralizing antibody.

CONCLUSIONS

Our findings suggest that the JNK/Activator protein 1 pathway is involved in AM-induced VEGF expression in HO-8910 cells.

Diallyl trisulfide inhibits migration, invasion and angiogenesis of human colon cancer HT-29 cells and umbilical vein endothelial cells, and suppresses murine xenograft tumour growth

Angiogenesis inhibitors are beneficial for the prevention and treatment of angiogenesis-dependent diseases including cancer. We examined the cytotoxic, anti-metastatic, anti-cancer and anti-angiogenic effects of diallyl trisulfide (DATS). In HT29 cells, DATS inhibited migration and invasion through the inhibition of focal adhesion kinase (FAK), extracellular signal-regulated kinase, c-Jun N-terminal kinase and p38 which was associated with inhibition of matrix metalloproteinases-2, -7 and -9 and VEGF. In human umbilical vein endothelial cells (HUVEC), DATS inhibited the migration and angiogenesis through FAK, Src and Ras. DATS also inhibited the secretion of VEGF. The capillary-like tube structure formation and migration by HUVEC was inhibited by DATS. The chicken egg chorioallantoic membrane (CAM) assay indicated that DATS treatment inhibited ex-vivo angiogenesis. We investigated the anti-tumour effects of DATS against human colon cancer xenografts in BALB/c^nu/nu mice and its anti-angiogenic activity in vivo. In this in-vivo study, DATS also inhibited the tumour growth, tumour weight and angiogenesis (decreased the levels of haemoglobin) in HT29 cells. In conclusion, the present results suggest that the inhibition of angiogenesis may be an important mechanism in colon cancer chemotherapy by DATS.

Fibroblast growth factor 2 induces E-cadherin down-regulation via PI3K/Akt/mTOR and MAPK/ERK signaling in ovarian cancer cells

Fibroblast growth factor 2 (FGF2) is produced by ovarian cancer cells and it has been suggested to play an important role in tumor progression. In this study, we report that FGF2 treatment down-regulated E-cadherin by up-regulating its transcriptional repressors, Slug and ZEB1, in human ovarian cancer cells. The pharmacological inhibition of phosphatidylinositol-3-kinase (PI3K), mammalian target of rapamycin (mTOR), and MEK suggests that both PI3K/Akt/mTOR and MAPK/ERK signaling are required for FGF2-induced E-cadherin down-regulation. Moreover, FGF2 up-regulated Slug and ZEB1 expression via the PI3K/Akt/mTOR and MAPK/ERK signaling pathways, respectively. Finally, FGF2-induced cell invasion was abolished by the inhibition of the PI3K/Akt/mTOR and MAPK/ERK pathways, and the forced expression of E-cadherin diminished the intrinsic invasiveness of ovarian cancer cells as well as the FGF2-induced cell invasion. This study demonstrates a novel mechanism in which FGF2 down-regulates E-cadherin expression through the activation of PI3K/Akt/mTOR and MAPK/ERK signaling, and the up-regulation of Slug and ZEB1 in human ovarian cancer cells.

T-cadherin expression in uterine leiomyoma

OBJECTIVE

T-cadherin is a tumor-suppressor with low expression in many malignant tumors, but with high expression in endothelial cells and so on. In this study we investigated whether T-cadherin was expressed and if together with bFGF play a role in the occurrence and development of uterine leiomyoma.

METHOD

Uterine leiomyoma, the adjacent normal myometrium, control normal myometrium without uterine leiomyoma and vascular features of myoma were collected. Immunohistochemistry, western blot and relative quantitative real time PCR were used to evaluate bFGF and T-cadherin on the three specimens. Data were statistically analysed.

RESULTS

T-cadherin was observed on the leiomyoma cellular layers but not in the endochylema, extracellular matrix and leiomyoma vascular endothelial cell, bFGF in the leiomyoma endochylema but not observed in the extracellular matrix and leiomyoma vascular endothelial cell. The protein and mRNA expression of bFGF and T-cadherin in uterine leiomyoma were significantly with higher expression than that in adjacent normal myometrium and control normal myometrium. In addition, T-cadherin correlated well with bFGF. There was relationship between T-cadherin and color Doppler flow imaging (CDFI).

CONCLUSION

bFGF and T-cadherin have high expressions in uterine leiomyoma, and T-cadherin is associated with CDFI, indicating that a cross talk between bFGF and T-cadherin plays an important role in the occurrence and development of uterine leiomyoma or even malignant tumors.

The roles of fibroblast growth factors in the testicular development and tumor

Fibroblast growth factors (FGFs) are classically known as hormonal factors and recent studies have revealed that FGFs have a key role in regulating growth and development of several reproductive organs, including the testis. The testis is mainly consisted of germ cells, Sertoli cells and Leydig cells to develop and maintain the male phenotype and reproduction. This review summarizes the structure and fuctions of testis, the roles of FGFs on testicular development and potential involvement in testicular tumor and its regulatory mechanism. Among 23 members of FGFs, the FGF-1, FGF-2, FGF-4, FGF-8, FGF-9, and FGF-21 were involved and describe in details. Understanding the roles and mechanism of FGFs is the foundation to modeling testicular development and treatments in testicular disease. Therefore, in the last part, the potential therapy with FGFs for the testis of cancer and diabetes was also discussed.

Inhibition of xenograft human glioma tumor growth by lentivirus-mediated gene transfer of alphastatin

Angiogenesis is crucial for the development and metastasis of human brain glioma. Based on our previous successful construction of a lentivirus-mediated alphastatin (an endogenous angiogenesis inhibitor) gene transfer system and our findings that alphastatin exhibited potent inhibitory effects on the migration and differentiation of human umbilical vein endothelial cell lines (HUVECs) induced by vascular endothelial growth factor (VEGF) or basic fibroblast growth factor (bFGF) in vitro, here, we investigated the effect of using lentiviral vectors to overexpress alphastatin in human glioma cells to show whether sustained long-term expression of alphastatin diminishes tumor growth in a xenograft glioma model. We found that the transduced glioma cells sustainedly secreted alphastatin, which did not affect the proliferative ability of the glioma cells. Furthermore, tumor xenografts treated with the recombinant lentivirus were significantly smaller compared to the control xenografts and vascularity within the treated tumors was evidently decreased. Our data suggest that stable expression of alphastatin inhibits human glioma growth by inhibiting angiogenesis, with a probable mechanism of suppressing the turnover of VE-cadherin membrane molecules.

Gleditsioside B, a triterpene saponin isolated from the anomalous fruits of Gleditsia sinensis Lam., abrogates bFGF-induced endothelial cell migration through preventing the activation of MMP-2 and FAK via inhibiting ERK and PI3K/AKT signaling pathways

Angiogenesis has become an attractive target for the treatment of certain diseases such as cancer and rheumatoid arthritis. Our previous studies demonstrated that the saponin fraction from Gleditsia sinensis fruits had anti-angiogenic potential, and Gleditsiosides B (GB) was probably the main active constituent. In the present study, we assessed the effect of GB on endothelial cell migration, a crucial event in angiogenesis, and explored the underlying mechanisms. The migration of endothelial cells was assessed by transwell. The expressions of MMP-2/-9 and TIMP-1/-2 were analyzed by Western blotting, and the activities of MMP-2/-9 were detected by gelatin zymography assay. Moreover, migration-related proteins and signaling pathways, including FAK, MAPKs and PI3K/AKT, were analyzed by Western blotting. It was shown that GB, at a concentration of 10 μM without significant cytotoxicity, could effectively abrogate the migration of human umbilical vein endothelial cells (HUVECs) induced by bFGF. GB also inhibited the expression and activity of MMP-2, elevated the expression of TIMP-1, and restrained the phosphorylations of FAK, ERK, PI3K and AKT in a concentration-dependent manner. The findings suggest that GB was able to abrogate the migration of endothelial cells through down-regulating the activation of MMP-2 and FAK via preventing ERK and PI3K/AKT signaling pathways.

N-cadherin prodomain processing regulates synaptogenesis

Classical cadherins, which are adhesion molecules functioning at the CNS synapse, are synthesized as adhesively inactive precursor proteins in the endoplasmic reticulum (ER). Signal sequence and prodomain cleavage in the ER and Golgi apparatus, respectively, activates their adhesive properties. Here, we provide the first evidence for sorting of nonadhesive precursor N-cadherin (ProN) to the neuronal surface, where it coexists with adhesively competent mature N-cadherin (N-cad), generating a spectrum of adhesive strengths. In cultured hippocampal neurons, a high ProN/N-cad ratio downregulates synapse formation. Neurons expressing genetically engineered uncleavable ProN make markedly fewer synapses. The synapse number can be rescued to normality by depleting surface ProN levels through prodomain cleavage by an exogenous protease. Finally, prodomain processing is developmentally regulated in the rat hippocampus. We conclude that it is the ProN/N-cad ratio and not mature N-cad alone that is critical for regulation of adhesion during synaptogenesis.

Critical role of c-Jun N-terminal kinase in regulating bFGF-induced angiogenesis in vitro

Angiogenesis, the process of new blood vessels formation, is a critical step for wound healing, tumour growth and metastasis, diabetic retinopathy, psoriasis, etc. The present study was designed to investigate whether c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) is critical for regulating basic fibroblastic growth factor (bFGF)-induced angiogenesis in human umbilical vein endothelial cells (HUVECs). Our results showed that bFGF-induced HUVECs proliferation, migration and tube formation with a concentration-dependent manner. Further results showed that bFGF induced the phosphorylation of JNK/SAPK at 15 min. Both JNK/SAPK inhibitor SP600125 and JNK/SAPK peptide inhibitor 420116 could inhibit bFGF-induced HUVECs proliferation, migration and tube formation, so did JNK/SAPK-specific siRNA. Moreover, when HUVECs were stimulated with bFGF, upstream signals of JNK/SAPK, SEK1/MKK4 and MKK7 were both activated at 2 min. In summary, our results indicate that JNK/SAPK signal pathway plays an important role in regulating bFGF-mediated angiogenesis in HUVECs, which may therefore be a new therapeutic approach for the treatment of angiogenesis-associated diseases.

Integrins as "functional hubs" in the regulation of pathological angiogenesis

It is well accepted that complex biological processes such as angiogenesis are not controlled by a single family of molecules or individually isolated signaling pathways. In this regard, new insight into the interconnected mechanisms that regulate angiogenesis might be gained by examining this process from a more global network perspective. The coordination of signaling cues from both outside and inside many different cell types is required for the successful completion of angiogenesis. Evidence is accumulating that the multifunctional integrin family of cell adhesion receptors represent an important group of molecules that play active roles in sensing, integrating, and distributing a diverse set of signals that regulate many cellular events required for angiogenesis. Given the ability of integrins to bind numerous extracellular ligands and transmit signals in a bi-directional fashion, we will discuss the multiple ways by which integrins may serve as a functional hub during pathological angiogenesis. In addition, we will highlight potential imaging and therapeutic strategies based on the expanding new insight into integrin function.

Matrix metalloproteinase-activated anthrax lethal toxin inhibits endothelial invasion and neovasculature formation during in vitro morphogenesis

Solid tumor growth is dependent on angiogenesis, the formation of neovasculature from existing vessels. Endothelial activation of the extracellular signal-regulated kinase 1/2, c-jun NH(2)-terminal kinase, and p38 mitogen-activated protein kinase pathways is central to this process, and thus presents an attractive target for the development of angiogenesis inhibitors. Anthrax lethal toxin (LeTx) has potent catalytic mitogen-activated protein kinase inhibition activity. Preclinical studies showed that LeTx induced potent tumor growth inhibition via the inhibition of xenograft vascularization. However, LeTx receptors and the essential furin-like activating proteases are expressed in many normal tissues, potentially limiting the specificity of LeTx as an antitumor agent. To circumvent nonspecific LeTx activation and simultaneously enhance tumor vascular targeting, a substrate preferably cleaved by the gelatinases class of matrix metalloproteinases (MMP) was substituted for the furin LeTx activation site. In vivo efficacy studies showed that this MMP-activated LeTx inhibited tumor xenografts growth via the reduced migration of endothelial cells into the tumor parenchyma. Here we have expanded on these initial findings by showing that this MMP-activated LeTx reduces endothelial proangiogenic MMP expression, thus causing a diminished proteolytic capacity for extracellular matrix remodeling and endothelial differentiation into capillary networks. Additionally, our data suggest that inhibition of the c-jun NH(2)-terminal kinase and p38, but not extracellular signal-regulated kinase-1/2, pathways is significant in the antiangiogenic activity of the MMP-activated LeTx. Collectively, these results support the clinical development of the MMP-activated LeTx for the treatment of solid tumors.