Inhibition of angiogenic properties of brain endothelial cells by platelet-derived sphingosine-1-phosphate

A comparative evaluation of a novel vaccine in APP/PS1 mouse models of Alzheimer's disease

Immunization against amyloid-beta-peptide (Aβ) has been widely investigated as a potential immunotherapeutic approach for Alzheimer's disease (AD). With the aim of developing an active immunogenic vaccine without need of coadjuvant modification for human trials and therefore avoiding such side effects, we designed the Aβ_1–42 vaccine (EB101), delivered in a liposomal matrix, that based on our previous studies significantly prevents and reverses the AD neuropathology, clearing Aβ plaques while markedly reducing neuronal degeneration, behavioral deficits, and minimizing neuroinflammation in APP/PS1 transgenic mice. Here, the efficacy of our immunogenic vaccine EB101 was compared with the original immunization vaccine cocktail Aβ₄₂ + CFA/IFA (Freund's adjuvant), in order to characterize the effect of sphingosine-1-phosphate (S1P) in the immunotherapeutic response. Quantitative analysis of amyloid burden showed a notable decrease in the neuroinflammation reaction against Aβ plaques when S1P was compared with other treatments, suggesting that S1P plays a key role as a neuroprotective agent. Moreover, EB101 immunized mice presented a protective immunogenic reaction resulting in the increase of Aβ-specific antibody response and decrease of reactive glia in the affected brain areas, leading to a Th2 immunological reaction.

Evidence of MTCBP-1 interaction with the cytoplasmic domain of MT1-MMP: Implications in the autophagy cell index of high-grade glioblastoma

Progression of astrocytic tumors is, in part, related to their dysregulated autophagy capacity. Recent evidence indicates that upstream autophagy signaling events can be triggered by MT1-MMP, a membrane-bound matrix metalloproteinase that contributes to the invasive phenotype of brain cancer cells. The signaling functions of MT1-MMP require its intracellular domain, and recent identification of MTCBP-1, a cytoplasmic 19 kDa protein involved in the inhibition of MT1-MMP-mediated cell migration, suggests that modulation of MT1-MMP cytoplasmic domain-mediated signaling may affect other carcinogenic processes. Using qPCR and screening of cDNA generated from brain tumor tissues of grades I, II, III, and IV, MT1-MMP gene expression was found to correlate with increased grade of tumors. Inversely, MTCBP-1 expression decreased with increasing grade of brain tumor. Confocal microscopy and fluorescence resonance energy transfer (FRET) analysis revealed that overexpressing a cytoplasmic-deleted MT1-MMP recombinant protein mutant prevented MTCBP-1 recruitment to the intracellular leaf of plasma membrane in U87 glioblastoma cells. The interaction between MTCBP-1 and the 20 amino acids peptide representing the MT1-MMP cytoplasmic domain was confirmed by surface plasmon resonance. Overexpression of a full-length Wt-MT1-MMP triggered acidic autophagy vesicle formation and autophagic puncta formation for green fluorescent microtubule-associated protein 1 light chain 3 (GFP-LC3). Autophagic vesicles and GFP-LC3 puncta formation were abrogated in the presence of MTCBP-1. Our data elucidate a new role for MTCBP-1 regulating the intracellular function of MT1-MMP-mediated autophagy. The inverse correlation between MTCBP-1 and MT1-MMP expression with brain tumor grades could also contribute to the decreased autophagic index observed in high-grade tumors.

Thy-1-induced migration inhibition in vascular endothelial cells through reducing the RhoA activity

Our previous study indicated that Thy-1, which is expressed on blood vessel endothelium in settings of pathological and a specific of physiological, but not during embryonic, angiogenesis, may be used as a marker for angiogenesis. However, the function of Thy-1 during angiogenesis is still not clear. Here, we demonstrate that knock-down of the endogenous Thy-1 expression by Thy-1 siRNA transfection promoted the migration of human umbilical vein endothelial cells (HUVEC). In contrast, treatment with interleukin-1β (IL-1β) or phorbol-12-myristate-13-acetate (PMA) increased the level of Thy-1 protein and reduced the migration of HUVEC. These effects were abolished by pre-transfection of HUVEC with Thy-1 siRNA to knock-down the expression of Thy-1. Moreover, over-expression of Thy-1 by transfection of HUVEC with Thy-1 pcDNA3.1 decreased the activity of RhoA and Rac-1 and inhibited the adhesion, migration and capillary-like tube formation of these cells. These effects were prevented by co-transfection of the cell with constitutively active RhoA construct (RhoA V14). On the other hand, pre-treatment with a ROCK (a kinase associated with RhoA for transducing RhoA signaling) inhibitor, Y27632, abolished the RhoA V14-induced prevention effect on the Thy-1-induced inhibition of endothelial cell migration and tube formation. Taken together, these results indicate that suppression of the RhoA-mediated pathway might participate in the Thy-1-induced migration inhibition in HUVEC. In the present study, we uncover a completely novel role of Thy-1 in endothelial cell behaviors.

Vaccine Development to Treat Alzheimer's Disease Neuropathology in APP/PS1 Transgenic Mice

A novel vaccine addressing the major hallmarks of Alzheimer's disease (AD), senile plaque-like deposits of amyloid beta-protein (Aβ), neurofibrillary tangle-like structures, and glial proinflammatory cytokines, has been developed. The present vaccine takes a new approach to circumvent failures of previous ones tested in mice and humans, including the Elan-Wyeth vaccine (AN1792), which caused massive T-cell activation, resulting in a meningoencephalitis-like reaction. The EB101 vaccine consists of Aβ_1-42 delivered in a novel immunogen-adjuvant composed of liposomes-containing sphingosine-1-phosphate (S1P). EB101 was administered to APPswe/PS1dE9 transgenic mice before and after AD-like pathological symptoms were detectable. Treatment with EB101 results in a marked reduction of Aβ plaque burden, decrease of neurofibrillary tangle-like structure density, and attenuation of astrocytosis. In this transgenic mouse model, EB101 reduces the basal immunological interaction between the T cells and immune activation markers in the affected hippocampal/cortical areas, consistent with decreased amyloidosis-induced inflammation. Therefore, immunization with EB101 prevents and reverses AD-like neuropathology in a significant manner by halting disease progression without developing behavioral spatial deficits in transgenic mice.

ΑB-crystallin in clear cell renal cell carcinoma: tumor progression and prognostic significance

OBJECTIVES

AlphaB-crystallin (αB-crystallin), a small heat shock protein, has been reported to be involved in the growth, antiapoptosis, migration, and chemoresistance of human malignancies.

MATERIALS AND METHODS

αB-crystallin expression in normal renal and clear cell renal cell carcinoma (ccRCC) tissues was examined with two-dimensional (2D) gel electrophoresis assays. Immunohistochemistry was conducted to determine the presence of αB-crystallin-positive tumor cells and staining intensity in 50 cases of ccRCC tissue samples. The association of αB-crystallin protein expression, clinicopathogic parameters and prognosis of ccRCC patients was also analyzed with Student's t-test and Kaplan-Meier analysis. Moreover, Western blot assays were performed to detect the protein expression of αB-crystallin in normal and tumor tissues and the alteration of cell cycle regulators in αB-crystallin-overexpressing cells. MTT (3-[4,5-dimethythiazol-2-yl]-2,5-diphenyltetrazolium bromide), BrdU, and transwell assays were performed to demonstrate the effects of αB-crystallin overexpression on cell growth, DNA synthesis and cell migration of ccRCC cells, respectively.

RESULTS

The results showed the up-regulation of αB-crystallin expression in ccRCC tissues. Overall survival of ccRCC patients was significantly correlated with αB-crystallin expression in tumor tissues. We found that αB-crystallin overexpression increased the expression of cyclin A and the incorporation of BrdU, which may be related to the enhancement of cell growth. Transwell analyses demonstrated that presence of αB-crystallin overexpression enhanced cell migration in ccRCC cells. Furthermore, rapamycin-resistance of tumor cells was induced when αB-crystallin was overexpressed.

CONCLUSIONS

Our experimental findings highlight the importance of αB-crystallin in the tumor growth, migration, and target therapy-resistance of ccRCC cells.

Perlecan domain V is neuroprotective and proangiogenic following ischemic stroke in rodents

Stroke is the leading cause of long-term disability and the third leading cause of death in the United States. While most research thus far has focused on acute stroke treatment and neuroprotection, the exploitation of endogenous brain self-repair mechanisms may also yield therapeutic strategies. Here, we describe a distinct type of stroke treatment, the naturally occurring extracellular matrix fragment of perlecan, domain V, which we found had neuroprotective properties and enhanced post-stroke angiogenesis, a key component of brain repair, in rodent models of stroke. In both rat and mouse models, Western blot analysis revealed elevated levels of perlecan domain V. When systemically administered 24 hours after stroke, domain V was well tolerated, reached infarct and peri-infarct brain vasculature, and restored stroke-affected motor function to baseline pre-stroke levels in these multiple stroke models in both mice and rats. Post-stroke domain V administration increased VEGF levels via a mechanism involving brain endothelial cell α5β1 integrin, and the subsequent neuroprotective and angiogenic actions of domain V were in turn mediated via VEGFR. These results suggest that perlecan domain V represents a promising approach for stroke treatment.

CC-PLA2-1 and CC-PLA2-2, two Cerastes cerastes venom-derived phospholipases A2, inhibit angiogenesis both in vitro and in vivo

Integrins are essential in the complex multistep process of angiogenesis and are thus attractive targets for the development of antiangiogenic therapies. Integrins are antagonized by disintegrins and C-type lectin-like proteins, two protein families from snake venom. Here, we report that CC-PLA2-1 and CC-PLA2-2, two novel secreted phospholipases A(2) (PLA(2)) isolated from Cerastes cerastes venom, also showed anti-integrin activity. Indeed, both PLA(2)s efficiently inhibited human brain microvascular endothelial cell adhesion and migration to fibrinogen and fibronectin in a dose-dependent manner. Interestingly, we show that this anti-adhesive effect was mediated by alpha5beta1 and alphav-containing integrins. CC-PLA2s also impaired in vitro human brain microvascular endothelial cell tubulogenesis on Matrigel and showed antiangiogenic activity in vivo in chicken chorioallantoic membrane assay. The complete PLA(2) cDNAs were cloned from a venom gland cDNA library. Mature CC-PLA2-1 and CC-PLA2-2 contain 121 and 120 amino acids, respectively, including 14 cysteines each and showed 83% identity. Tertiary model structures of CC-PLA2-1 and CC-PLA2-2 were generated by homology modeling. This is thus the first study describing an antiangiogenic effect for snake venom PLA(2)s and reporting first clues to their mechanism of action on endothelial cells.

Terbinafine inhibits endothelial cell migration through suppression of the Rho-mediated pathway

We showed previously that terbinafine, an allylamine with fungicidal activity, could inhibit angiogenesis by suppressing the endothelial cell proliferation. In the present study, we further showed that terbinafine (0-120 micromol/L) dose dependently inhibited the adhesion and migration of human umbilical vascular endothelial cells (HUVEC). Western blot analysis showed that terbinafine decreased the levels of Ras protein and membrane-bound RhoA protein. Moreover, the terbinafine-induced migration inhibition in HUVEC was prevented by pretreatment with farnesol or geranylgeraniol. Pretreatment of HUVEC with Ras inhibitor peptide or a ROCK (a kinase associated with RhoA for transducing RhoA signaling) inhibitor, Y27632, abolished the farnesol- or geranylgeraniol-induced prevention effect on the terbinafine-induced migration inhibition, respectively. These data suggest that the consuming or depletion of geranylgeranyl pyrophosphate and consequent suppression of protein geranylgeranylation and farnesylation, which is essential for activation of Rho GTPases and Ras, respectively, might account for the terbinafine-induced inhibition of HUVEC migration. The levels of phosphorylated focal adhesion kinase and paxillin protein and the mRNA levels of matrix metalloproteinase-2 and matrix metalloproteinase-9 were also decreased by terbinafine treatment. Taken together, these results indicate that suppression of Rho-mediated pathway might be involved in the signal transduction leading to the inhibition of cell migration caused by terbinafine in HUVEC.

Src-dependent phosphorylation of membrane type I matrix metalloproteinase on cytoplasmic tyrosine 573: role in endothelial and tumor cell migration

Membrane type 1 matrix metalloproteinase (MT1-MMP) is a transmembrane MMP that plays important roles in migratory processes underlying tumor invasion and angiogenesis. In addition to its matrix degrading activity, MT1-MMP also contains a short cytoplasmic domain whose involvement in cell locomotion seems important but remains poorly understood. In this study, we show that MT1-MMP is phosphorylated on the unique tyrosine residue located within this cytoplasmic sequence (Tyr(573)) and that this phosphorylation requires the kinase Src. Using phosphospecific antibodies recognizing MT1-MMP phosphorylated on Tyr(573), we observed that tyrosine phosphorylation of the enzyme is rapidly induced upon stimulation of tumor and endothelial cells with the platelet-derived chemoattractant sphingosine-1-phosphate, suggesting a role in migration triggered by this lysophospholipid. Accordingly, overexpression of a nonphosphorylable MT1-MMP mutant (Y573F) blocked sphingosine-1-phosphate-induced migration of Human umbilical vein endothelial cells and HT-1080 (human fibrosarcoma) cells and failed to stimulate migration of cells lacking the enzyme (bovine aortic endothelial cells). Altogether, these findings strongly suggest that the Src-dependent tyrosine phosphorylation of MT1-MMP plays a key role in cell migration and further emphasize the importance of the cytoplasmic domain of the enzyme in this process.