VEGF-C promotes survival in podocytes

Vascular endothelial growth factor (VEGF)-A is an autocrine survival factor for podocytes, which express two VEGF receptors, VEGF-R1 and VEGF-R3. As VEGF-A is not a known ligand for VEGF-R3, the aim of this investigation was to examine whether VEGF-C, a known ligand for VEGF-R3, served a function in podocyte biology and whether this was VEGF-R3 dependent. VEGF-C protein expression was localized to podocytes in contrast to VEGF-D, which was expressed in parietal epithelial cells. Intracellular calcium ([Ca2+]i) experiments demonstrated that VEGF-C induced a 0.74 ± 0.09-fold reduction in [Ca2+]icompared with baseline in human conditionally immortalized podocytes (hCIPs; P < 0.05, one sample t-test, n = 8). Cytotoxicity experiments revealed that in hCIPs VEGF-C reduced cytotoxicity to 81.4 ± 1.9% of serum-starved conditions ( P < 0.001, paired t-test, n = 16), similar to VEGF-A (82.8 ± 4.5% of serum-starved conditions, P < 0.05, paired t-test). MAZ51 (a VEGF-R3 kinase inhibitor) inhibited the VEGF-C-induced reduction in cytotoxicity (106.2 ± 2.1% of serum-starved conditions), whereas MAZ51 by itself had no cytotoxic effects on hCIPs. VEGF-C was also shown to induce a 0.5 ± 0.13-fold reduction in levels of MAPK phosphorylation compared with VEGF-A and VEGF-A-Mab treatment ( P < 0.05, ANOVA, n = 4), yet had no effect on Akt phosphorylation. Surprisingly, immunoprecipitation studies detected no VEGF-C-induced autophosphorylation of VEGF-R3 in hCIPs but did so in HMVECs. Moreover, SU-5416, a tyrosine kinase inhibitor, blocked the VEGF-C-induced reduction in cytotoxicity (106 ± 2.8% of serum-starved conditions) at concentrations specific for VEGF-R1. Together, these results suggest for the first time that VEGF-C acts in an autocrine manner in cultured podocytes to promote survival, although the receptor or receptor complex activated has yet to be elucidated.

Local VEGF activity but not VEGF expression is tightly regulated during diabetic nephropathy in man

Several studies have implicated the angiogenic cytokine vascular endothelial growth factor (VEGF) in the development of diabetic nephropathy, but no data are available about its local activity during human disease. Glomeruli from 52 archival biopsies from type II diabetics were evaluated and compared to 10 renal biopsies without kidney disease (controls). Glomerulosclerosis, capillary rarefaction, glomerular and endothelial cell proliferation, apoptosis, VEGF expression, as well as receptor-bound VEGF indicating local VEGF activity, and phosphorylation of the signal transduction molecule Akt were investigated. Owing to substantial heterogeneity of glomerular lesions in individual biopsies, these parameters were correlated with the degree of injury in individual glomeruli rather than biopsies. Severe glomerular capillary rarefaction was linked to the degree of glomerulosclerosis. While cellular apoptosis was detected independent of the stage of injury, endothelial cell proliferation indicating capillary repair was markedly increased only in mildly/moderately injured glomeruli. In controls, VEGF was predominantly expressed in podocytes, whereas receptor-bound VEGF was confined to the glomerular endothelium. VEGF expression was increased in all diabetic glomeruli by many different cell types. In contrast, VEGF receptor activation was increased predominantly in the endothelium of only mildly injured glomeruli, but significantly decreased in more severely injured glomeruli. Diabetic nephropathy is associated with glomerular capillary rarefaction. Despite overall increased glomerular VEGF, the decreased receptor-bound VEGF on the endothelium may be an indicator of an insufficient capillary repair reaction.

Autocrine VEGF-A system in podocytes regulates podocin and its interaction with CD2AP

Vascular endothelial growth factor (VEGF-A) signaling is required for endothelial cell differentiation, vasculogenesis, angiogenesis, and vascular patterning. During kidney morphogenesis, podocyte VEGF-A guides endothelial cells toward developing glomeruli. Podocyte VEGF-A expression continues throughout life but its function after completion of development remains unclear. Here, we examined the expression of VEGF-A and its receptors VEGFR1, VEGFR2, NP1, and NP2 in conditionally immortalized mouse podocytes cultured in undifferentiated and differentiated conditions using RT-PCR and Western analysis. VEGF-A secretion was assessed by ELISA and Western analysis. Upon podocyte differentiation, VEGF-A protein expression and secretion increased threefold. Differentiated podocytes expressed eightfold higher VEGFR2 mRNA levels than undifferentiated podocytes, whereas VEGFR1, sVEGFR1, NP1, and NP2 mRNA levels were similar. We examined the regulation and function of the VEGF-A system by exposing differentiated podocytes to recombinant VEGF(165) (20 ng/ml) or control media for 24 h. VEGF(165) induced a twofold increase in VEGFR2 mRNA and protein levels, whereas VEGFR1, sVEGFR1, NP1, and NP2 mRNA levels remained unchanged. VEGF(165) induced VEGFR2 phosphorylation. VEGF(165) reduced podocyte apoptosis approximately 40%, whereas anti-VEGFR2 neutralizing antibody enhanced it twofold. We determined that VEGF-A signaling regulates slit diaphragm proteins by inducing a dose-response podocin upregulation and increasing its interaction with CD2AP. The data indicate that podocytes in culture have a functional autocrine VEGF-A system that is regulated by differentiation and ligand availability. VEGF-A functions in podocytes include promoting survival through VEGFR2, inducing podocin upregulation and increasing podocin/CD2AP interaction.

A pilot study investigating a novel subcutaneously implanted pre-cellularised scaffold for tissue engineering of intestinal mucosa

Tissue engineering of the small intestine offers an alternative to long-term intravenous nutrition and transplantation in patients with intestinal failure. Initial work, although encouraging, is limited by the volume of neonatal tissue required to produce a small neomucosal cyst. Our novel approach is to implant tubular poly-lactide-co-glycolide (PGLA) foam scaffolds subcutaneously. The aim of this study was to investigate whether these scaffolds would support growth of intestinal neomucosa. PGLA scaffolds were implanted subcutaneously into 8 Lewis rats; after 5 weeks, 'organoid units' were injected into the lumens. Tissue was assessed histologically after harvesting and quantitative immunohistochemistry was performed using antibodies against vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 2 (VEGF-R2), fibroblast growth factor basic (bFGF) and fibroblast growth factor receptor 2 (FGF-R2). At 4 weeks post organoid unit implantation, clearly recognisable mucosa and submucosa was present on the luminal surface of the scaffold. Densities of VEGF and VEGF-R2 positive cells increased with time post organoid unit implantation. This pilot study demonstrates that it is possible to tissue engineer small intestinal neomucosa using subcutaneously implanted PLGA scaffolds. The yield of the process compares favourably to the published literature. Further work is required to optimise the technique.

In vitro and in vivo evaluation of [123I]-VEGF165 as a potential tumor marker

One of the research challenges in oncology is to develop new biochemical methods for noninvasive tumor therapy evaluation to determine whether the chemotherapeutics is effective. Vascular endothelial growth factor (VEGF) was labeled with radioiodine and evaluated in vitro as well as in vivo, using A2058, a melanoma cell line overexpressing VEGFR-1 and -2. Saturation binding analysis with [(125)I]-VEGF resulted in a K(d) of 0.1 nM. Internalization assays indicate the preserved ligand induced internalization and metabolization of the tracer. Biodistribution studies with [(123)I]-VEGF in wild type and A2058 tumor-bearing athymic mice showed low background activity and a tumor to reference tissue ratio of maximum 6.12. These results suggest that [(123)I]-VEGF is a potentially suitable tracer for tumor therapy evaluation.

Orbital Metastasis from Prostate Cancer: An Atypical Case of Neuroendocrine Dedifferentiation During Progression from Hormone-Sensitive to Refractory Stage

We report a case of orbital metastasis from a neuroendocrine dedifferentiated prostate cancer during progression from hormone-sensitive to hormone refractory stage. A patient receiving androgen deprivation for hormone-sensitive prostate cancer presented with sudden-onset right-sided ptosis and an increasing serum prostate-specific antigen level. Imaging studies revealed a mixed blastic and lytic lesion involving the right orbital wall and the right cavernous sinus. Comparison of the metastatic histology with the original pathology confirmed a histologic change to poorly differentiated prostate adenocarcinoma with neuroendocrine features. Local radiation of the lesion and palliative systemic chemotherapy resulted in marked short-term improvement of all presenting symptoms. Because prostate cancer metastasis involves hematogenous and lymphatic routes, we also evaluated expression of the vascular endothelial growth factor (VEGF) and receptors (VEGFR-1, VEGFR-2, and VEGFR-3) in the metastatic deposit by immunohistochemistry. Strong expression of VEGFR-2 and VEGFR-3 restricted to the malignant epithelium was noted. We recommend a second biopsy of atypical prostate metastasis associated with sudden change to aggressive clinical behavior in order to evaluate for dedifferentiation features before planning appropriate treatment interventions especially in patients who are candidates for systemic chemotherapy.

[Prognostic value of EGFR in colorectal cancer]

The prognostic value of EGFR expression in colorectal cancer, usually evaluated by immunohistochemistry, is actually based on heterogeneous data, considering tumour stage or survival rates. Results are variable due to differences in evaluation criteria between studies. The development of standardized scoring systems and the evaluation of expression variability in tumour led to reconsider this question. It seems to be important to evaluate precisely EGFR reactivity in the deepest region of the tumour. The finding of a profile linked to worse prognosis could allow pointing out tumours where EGFR overexpression is associated to disease progression and therefore could help to define EGFR- inhibitors' indications in colorectal cancer.

Human peripheral blood eosinophils induce angiogenesis

Eosinophils play a crucial role in allergic reactions and asthma. They are also involved in responses against parasites, in autoimmune and neoplastic diseases, and in fibroses. There is increasing evidence that angiogenesis plays an important role in these processes. Since eosinophils are known to produce angiogenic mediators, we have hypothesized a direct contribution of these cells to angiogenesis. The effect of human peripheral blood eosinophil sonicates on rat aortic endothelial cell proliferation (in vitro), rat aorta sprouting (ex vivo) and angiogenesis in the chick embryo chorioallantoic membrane (in vivo) have been investigated. To determine whether eosinophil-derived vascular endothelial growth factor influences the eosinophil pro-angiogenic activity, eosinophil sonicates were incubated with anti-vascular endothelial growth factor antibodies and then added to the chorioallantoic membrane. Vascular endothelial growth factor mRNA expression and vascular endothelial growth factor receptor density on the endothelial cells were also evaluated. Eosinophils were found to enhance endothelial cell proliferation and to induce a strong angiogenic response both in the aorta rings and in the chorioallantoic membrane assays. Pre-incubation of eosinophil sonicates with anti-vascular endothelial growth factor antibodies partially reduced the angiogenic response of these cells in the chorioallantoic membrane. Eosinophils also increased vascular endothelial growth factor mRNA production on endothelial cells. Eosinophils are able to induce angiogenesis and this effect is partially mediated by their pre-formed vascular endothelial growth factor. This strongly suggests an important role of eosinophils in angiogenesis-associated diseases such as asthma.

Metastatic properties of prostate cancer cells are controlled by VEGF

Mechanisms of metastasis, the major complication of prostate cancer, are poorly understood. In this study, we define molecular mechanisms that may contribute to the highly invasive potential of prostate cancer cells. Vascular endothelial growth factor (VEGF), its receptors (VEGFRs), and alpha5beta1 integrin were expressed by prostate cancer cells in vitro and by prostate tumors in vivo, and their expression was elevated at sites of bone metastasis compared to original prostate tumor. VEGF, through interaction with its receptors, regulated adhesive and migratory properties of the cancer cells. Specifically, the highly metastatic prostate cancer cell subline LNCaP-C4-2 showed a decreased adhesive but an enhanced migratory response to fibronectin, a ligand for alpha5beta1 integrin, compared to its nonmetastatic counterpart. A similar pattern was also observed when bone sialoprotein was used as a ligand in migration assays. Increased migration of metastatic prostate cancer cells to fibronectin and bone sialoprotein was regulated by VEGF via VEGFR-2. Tumor suppressor PTEN was involved in control of VEGF/VEGFR-2 stimulated prostate cancer cell adhesion as well as proliferation.

Age-dependent modifications of expression level of VEGF and its receptors in the inner ear

The mechanisms responsible for age-associated hearing loss are still incompletely characterized. In this study, we used a murine model of age-dependent hearing loss and evaluated whether this condition is associated with vascular modifications of the structures of the inner ear. We used old C57BL/6J mice that are affected by rapid and severe age-related hearing loss, and analyzed the expression pattern of vascular endothelial growth factor (VEGF), a prototypical angiogenic cytokine, and its receptors Flt-1 and Flk-1 in the inner ear. We report for the first time morphological and quantitative data about the expression of these crucial angiogenic molecules in the murine cochlea. We also show that in this animal model, cochlear VEGF expression is significantly reduced as a function of age. Our findings provide new evidence of possible interdependent relationships between aging, VEGF, and presbycusis, suggesting that vascular abnormalities might play a role in aging-associated hearing loss, with potentially important fundamental and clinical implications.

Sequential Expression of VEGF and its Receptors in Human Placental Villi During Very Early Pregnancy: Differences Between Placental Vasculogenesis and Angiogenesis

Vascularization within the human placenta is the result of the de novo formation of vessels derived from pluripotent precursor cells in the mesenchymal core of the villi. Vascularization of placental villi starts at around day 21 post conception (p.c.) with a four somite embryo. At this stage progenitors of haemangiogenic cells differentiate to form first vessels. These progenitor cells are thought to be directly derived from mesenchymal cells rather than originating from fetal blood cells. We investigated the relation between differentiation of stromal cells towards endothelial cells and vascular structures and the expression pattern of the respective growth factors. Using transmission electron microscopy and immunohistochemistry (for VEGF, Flt-1, Flk-1, CD14, CD34, and CD68) the development of placental vasculogenesis during very early stages of pregnancy (days 22-48 p.c.) was studied. We found that VEGF is strongly expressed in villous cytotrophoblast cells and subsequently in Hofbauer cells while its receptors Flt-1 and Flk-1 are found on vasculogenic and angiogenic precursor cells. The developmental expression and secretion of VEGF suggests its involvement in recruitment, maintenance and formation of first angiogenic cells and vessels. Interactions between VEGF and Flk-1 and Flt-1 may regulate placental vasculogenesis and angiogenesis in a paracrine and autocrine manner. The sequential expression of growth factors in different cell types may point to the fact that placental vasculogenesis and angiogenesis are clearly distinct events.

[Expression and action of vascular endothelial growth factor and its receptor in a rat model of retinopathy of prematurity]

OBJECTIVE

To explore the expression of vascular endothelial growth factor (VEGF) and its receptors (flt-1 and flk-1) in the retina of retinopathy of prematurity (ROP), and its relation to the alteration of retinal blood vessels.

METHODS

Eighty-six newborn Sprague-Dawley rats were randomly divided into hyperoxia and air groups, then each group was further divided into 1, 3, 7 and 14 days subgroups. The rats in hyperoxia group inhaled 75% oxygen and ROP model was thus set up. These animals were sacrificed respectively after 1, 3, 7 and 14 days, then the retinal endothelial cells were marked by CD34 to observe the change of retinal blood vessels. The expression of VEGF, flt-1 and flk-1 in the retina was measured by immunohistochemistry.

RESULTS

The retinal capillary density index (RCDI) in control group increased as days went on (F = 21.589, P < 0.01, but it was the least on the 7th day in hyperoxia group, after the rats had been returned to air for 7 days, RCDI increased significantly (F = 67.885, P < 0.01); In the control group, the expression of VEGF and flk-1 was the strongest in the retina on the 7th day, the result had significant difference as compared with the 1st and 14th day (P < 0.05). The expression of VEGF and flk-1 on the 7th day in hyperoxia group was weaker than that of control group (P < 0.05). But on the 14th day in hyperoxia group, they were stronger than that of control (P < 0.05). The localization of the expression of flt-1 was changed when blood vessels altered, but there was no significant difference in expression intensity as a whole (P > 0.05).

CONCLUSION

When the premature retina was exposed to hyperoxia, the expression of VEGF and flk-1 was reduced, and retinal blood vessels were also decreased; but the expression of VEGF and flk-1 was stronger in retina when premature rats were exposed to relative hypoxia, and the retinal blood vessels also increased significantly. It is concluded that VEGF and flk-1 may play important roles in the development of retinal blood vessels and its change in ROP. However, flt-1 has less effect compared with flk-1.

Elevated levels of vascular endothelial growth factor in serum of patients with D+ HUS

The pathogenesis of hemolytic uremic syndrome (D+ HUS) is characterized by endothelial damage of glomeruli and tubules within the kidney. In several other diseases in which glomerular endothelial damage occurs, elevated serum levels of vascular endothelial growth factor (VEGF) have been reported. VEGF is involved in angiogenesis, permeabilization of blood vessel endothelium, and wound repair. In this study we evaluated VEGF levels in the serum of 40 D+ HUS patients in the acute phase and during the course of the disease. VEGF levels were measured using a double-sandwich ELISA. Indirect immunohistochemistry was performed for the detection of VEGF in renal biopsy material of 3 HUS patients. Significantly elevated VEGF levels were found in HUS patients compared with controls in both serum ( P<0.001) and plasma ( P<0.05). A significant relationship was found between VEGF levels and severity of the disease according to the classification of Gianantonio ( P<0.05). Levels of VEGF in blood increased during the 2nd and 3rd week after HUS was diagnosed. Immunohistochemistry of renal biopsy material showed increased levels of the receptors for VEGF in the glomeruli. During the course of HUS, plasma VEGF levels increase and the increase is dependent on the severity of the disease. This is probably associated with the repair process.

[Expression of VEGFA, VEGFC, angiopoietin-1, angiopoietin-2 and their receptors on yolk sac blood island, aorta-gonad-mesonephros (AGM) region of human embryo]

The study was to investigate the expression of VEGFA, VEGFC, angiopoietin-1, angiopoietin-2 and their receptors on yolk sac blood island, AGM region during gestation of 3th-12th weeks of human embryo. Human embryo contingently aborted at 3 - 12 weeks of gestation were collected with signed agreements of the pregnant women suffered from accidental abortions. The specimens were fixed by 4% paraformaldehyde and embedded by paraffin. 5 micro m serial sections were made. HE and immunohistochemistry method (SABC) and light-microscope were employed. The results showed that VEGFA and its receptors flt1/flk-1, VEGFC and its receptor flt-4, angiopoietin-2 and its receptor tie-2 proteins were expressed strongly and angiopoietin-1 was weakly expressed by hematopoietic cells and vascular endothelial cells of blood island at 21 and 25 days of gestation. In the 4th week of gestation, immuno-positive reaction of these factors and their receptors appeared in the aorta and mesonephros deposited in larger, rounded and nucleated cells which represented hematopoietic cells. Up to 7th week, positive hematopoietic cells in the regions were much abundant. The number of positive cells decreased at 8th week. Up to 12th week, almost all blood cells were immuno-negative. VEGFA, flt-1, flt-4, angiopoietin-1, angiopoietin-2 and Tie-2 protein were expressed mainly by gonad at 6 - 8 weeks, but it did not express VEGFC and flk-1. The immuno-reaction of the factors and their receptors could not detected in vascular endothelial cells during 3-12th weeks of gestation. It is concluded that hematopoietic cells and endothelial cells in blood island of yolk sac, mesonephros and dorsal aorta co-expressed some factors and their receptors in relation to vasculogenesis and hematopoiesis. Intraembryonic hematopoiesis began in the 4th week of gestation.

Vascular endothelial growth factor (VEGF)-A and platelet-derived growth factor (PDGF) play a central role in the pathogenesis of digital clubbing

Digital clubbing is associated with many unrelated serious diseases but its pathogenesis remains a clinical enigma. It has been hypothesized that platelet clusters impacting in the distal vasculature mediate the morphological changes of clubbing. Since the multifunctional cytokines vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) are released on platelet aggregation and are hypoxically regulated, the present study has examined their role in clubbing using immunohistochemistry. Basic fibroblast growth factor (bFGF), transforming growth factor-beta 1 (TGF-beta1), microvessel density, carbonic anhydrase IX (CAIX), hypoxia inducible factor (HIF)-1alpha, and HIF-2alpha were also measured. There was a significant increase in VEGF (p = 0.01), pKDR (p = 0.03), PDGF (p = 0.017), and HIF-1alpha and HIF-2alpha (p = 0.004 and p = 0.004, respectively) expression together with a significant increase in microvessel density (p = 0.03) in the stroma in clubbed digits compared with controls. There was no difference in CAIX (p = 0.25), TGF-beta1 (p = 0.66) or bFGF (p = 0.18) between affected and control groups. These findings suggest that VEGF and PDGF are released after platelet impaction and that their expression is hypoxically enhanced in the stroma after capillary occlusion. VEGF may synergize with PDGF in inducing the stromal and vascular changes present in digital clubbing.

Bone marrow angiogenic ability and expression of angiogenic cytokines in myeloma: evidence favoring loss of marrow angiogenesis inhibitory activity with disease progression

We compared the angiogenic potential of bone marrow plasma and the expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and their receptors on plasma cells from patients with monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM), and newly diagnosed multiple myeloma (NMM). Cytokine and cytokine-receptor expression was studied by bone marrow immunohistochemistry, quantitative reverse transcription-polymerase chain reaction (RT-PCR) on sorted plasma cells, and quantitative Western blot analysis. Bone marrow angiogenic potential was studied using a human in vitro angiogenesis assay. The expression levels of VEGF, bFGF, and their receptors were similar among MGUS, SMM, and NMM. Sixty-one percent of NMM samples stimulated angiogenesis in the in vitro angiogenesis assay compared with SMM (0%) and MGUS (7%) (P <.001). Importantly, 63% of MGUS samples inhibited angiogenesis compared with SMM (43%) and NMM (4%) (P <.001). The inhibitory activity was heat stable, not overcome by the addition of VEGF, and corresponded to a molecular weight below 10 kd by size-exclusion chromatography. Our results suggest that increasing angiogenesis from MGUS to NMM is, at least in part, explained by increasing tumor burden rather than increased expression of VEGF/bFGF by individual plasma cells. The active inhibition of angiogenesis in MGUS is lost with progression, and the angiogenic switch from MGUS to NMM may involve a loss of inhibitory activity.

Activation of invasiveness of cervical carcinoma cells by angiotensin II

OBJECTIVE

Angiotensin II recently has been reported to promote the growth of several kinds of cells. In this study, we investigated the effect of angiotensin II on cervical carcinoma cells.

STUDY DESIGN

The expression of angiotensin II type I receptor was examined by immunohistochemistry in normal and neoplastic cervical tissues. Invasion assay was examined in Siha cells (cervical squamous cell carcinoma) and vascular endothelial growth factor levels were assayed with a vascular endothelial growth factor enzyme-linked immunosorbent assay kit.

RESULTS

Mean staining intensity level was stronger in invasive carcinoma cells than in normal, dysplasia, and carcinoma in situ tissues. Angiotensin II induced the secretion of vascular endothelial growth factor from Siha cells. Furthermore, angiotensin II promoted the invasive potential of Siha cells. These effects were reversed by the addition of anti-human vascular endothelial growth factor antibody and candesartan (antagonist of angiotensin II type I receptor).

CONCLUSION

Angiotensin II is involved in the progression of cervical carcinoma, because it induces the secretion of vascular endothelial growth factor through angiotensin II type I receptor, which results in the increased invasiveness of carcinoma cells.

Actin microdomains on endothelial cells: association with CD44, ERM proteins, and signaling molecules during quiescence and wound healing

During studies of the actin cytoskeleton in cultured endothelial cells we have observed that the luminal side of many cells contains F-actin microdomains that are rich in the hyaluronan receptor CD44 and in ezrin-radixin-moesin (ERM) proteins. A small subpopulation of the domains are also enriched in tyrosine phosphorylated proteins and signaling molecules. Confocal microscopy of rat aortic endothelial cells in situ demonstrated that similar microdomains occur in vivo. During healing of endothelial wounds, characteristic alterations of the actin cytoskeleton occurred. Thus, in many cells close to the wound, focal F-actin branching points appeared. The branching points were similar to the microdomains in that they colocalized with CD44 and ERM proteins, but, in addition, they formed centers for actin filament branching and were associated with phosphorylated protein kinase C alpha/betaII. These colocalization data are consonant with the view that activated PKC is responsible for activating ERM-mediated crosslinking between CD44 and the actin cytoskeleton. Importantly, inhibition of PKC activity decreased staining for phosphorylated ERM proteins, decreased the frequency of F-actin branching points, and inhibited monolayer wound healing. Together, our data show that endothelial cells contain a novel actin cytoskeletal structure, the F-actin microdomain, and suggest that during wound healing such structures become associated with activated signaling molecules and thereby enhance actin cytoskeletal remodeling.

[The effect of all-trans retinoid acid and sodium selenite (Na2SeO3) on VEGF and its receptor expression in HL-60 cells]

In order to investigate the effect of non-medullar toxicity drug - all trans retinoid acid (ATRA) and cancer preventive trace element-selenium compound - sodium selenite (Na(2)SeO(3)) on the expression of vascular endothelial growth factor (VEGF) and its receptor in HL-60 cells, the expression of VEGF and its receptor in HL-60 cells were detected by ELISA technique and flow cytometry before and after treatment with two drugs. The results showed that the mean VEGF concentrations in the cultural supernatant of 5 and 10 micro mol/L ATRA-treated HL-60 cells for 48 and 72 hours were lower than those of the control group without adding ATRA. The differences between the ATRA-treated groups and the control group were statistically significant (P = 0.001, P = 0.000, P < 0.01, respectively). The levels of VEGF-R on the surface of HL-60 cells also decreased after treatment with ATRA of 5 and 10 micro mol/L for 72 hours, but at 48 hours the expression rates of VEGF-R on HL-60 cells of the two ATRA treated groups were not significantly decreased. At 48 and 72 hours, Na(2)SeO(3) of 5 and 10 micro mol/L had no obvious effect on HL-60 secreting VEGF, but notablely inhibited the expression of VEGF-R. In conclusion, ATRA could inhibit the expression of VEGF and its receptor in HL-60 cell. Na(2)SeO(3) could not inhibit the expression of VEGF in HL-60 cell, but could decrease the receptor expression of VEGF, which mechanism should be further studied. ATRA and Na(2)SeO(3) had not obvious medullar-inhibition, but anti-angiogenesis activity. It is suggested that combination of two drugs with conventional therapy may enhance the effect of radiotherapy and chemotherapy, and reduce the dose and thus toxicity of chemotherapeutic agents.

Vascular endothelial growth factor (VEGF) receptor neuropilin-1's distribution in astrocytic tumors

Neuropilin-1 is a VEGF165- and semaphorin receptor expressed by endothelial cells and tumor cells. The specific function of neuropilin-1 is not fully known, but in the developing nervous system neuropilin, as a semaphorin receptor, has been shown to influence neuronal guidance. The expression of neuropilin-1 was studied in low-grade and high-grade astrocytic tumors, the latter characterized by extensive angiogenesis. We examined 20 low-grade astrocytomas (WHO grade II) and 46 glioblastomas (WHO grade IV) immunohistochemically for neuropilin-1, p53 and EGFR. The glioblastomas were according to the p53 and EGFR expression classified as 35 primary--de novo--glioblastomas, 9 secondary glioblastomas, and 2 uncertain cases. Furthermore, the presence of mast cells was evaluated to search for any potential function in angiogenesis. The glioblastomas expressed neuropilin-1 in the endothelial cells of the proliferating vessels and the majority of the glioblastomas had immunoreactive neoplastic astrocytes, with no difference between the glioblastoma subgroups. Six out of twenty of the low-grade astrocytomas were negative in the endothelial cells and 8 out of 20 in the tumor cells for neuropilin-1. Mast cells were observed in the collagen matrix around larger vessels in the leptomeninges, but not adjacent to malignant tumor vessels or as part of the tumor process itself. Increased expression of neuropilin-1 is shown in endothelial cells and in neoplastic astrocytes of glioblastomas. Less neuropilin-1 expression is found in about half of the low-grade astrocytomas in both neoplastic astrocytes and endothelial cells. The results suggest a correlation between neuropilin-1 and vascularity in human astrocytic tumors and a possible role for neuropilin-1 as a receptor for VEGF-induced angiogenesis.

Localisation of members of the vascular endothelial growth factor (VEGF) family and their receptors in human atherosclerotic arteries

BACKGROUND

Vascular endothelial growth factor (VEGF) mediates endothelial cell mitogenesis and enhances vascular permeability. The existence of single or multiple VEGF isoforms and receptors suggests that these proteins may have overlapping but distinct functions, which may be reflected in their cell expression and distribution.

METHODS

The localisation of VEGFs A-C and their receptors (VEGFRs 1-3, respectively) in 30 fresh human atherosclerotic arteries, 15 normal uterine arteries, and 15 saphenous veins using immunohistochemistry and western blotting.

RESULTS

Saphenous veins showed no staining for VEGF-B or VEGFR-2. Smooth muscle cells (SMCs) showed the strongest staining for VEGF-A, VEGF-B, VEGFR-1, and VEGFR-2 in all specimens. Conversely, VEGFR-3 and VEGF-C were predominantly localised to the endothelial vasa vasorum in normal arteries, whereas medial SMCs showed the strongest staining in atherosclerotic arteries. Western blotting showed variations in VEGF protein localisation, with lower amounts of VEGF-B and VEGF-C in saphenous veins, compared with arterial tissue. Amounts of VEGF-C were lower than those of VEGF-A and VEGF-B in all specimens.

CONCLUSION

This study provides direct evidence of the presence of VEGF proteins and receptors in human physiology and pathology, with variations in both the amounts of VEGF proteins expressed and their cellular distribution in normal arteries compared with atherosclerotic arteries. The presence of VEGFs A-C and their receptors in normal arterial tissue implies that VEGF functions may extend beyond endothelial cell proliferation. Reduced VEGFR-2 staining in atherosclerotic arteries may have implications for the atherosclerosis process and the development of vascular disease and its complications.

In vivo regulation of mRNA expression of vascular endothelial growth factor receptors (KDR and flt-1) in the human oviduct

OBJECTIVE

To examine the localization of vascular endothelial growth factor receptors (VEGF-R) and the changes in VEGF-R messenger ribonucleic acid (mRNA) expression in various regions of the oviduct from fertile women throughout the ovulatory cycle.

DESIGN

Prospective observational study.

SETTING

University-based obstetrics and gynecology department.

PATIENT(S)

Twenty-two women who underwent laparoscopic tubal sterilization or hysterectomy for a benign gynecological condition.

INTERVENTION(S)

The mucosal layer was isolated from the oviduct tissue. Immunohistochemistry and a semiquantitative reverse-transcriptase-polymerase chain reaction (RT-PCR) was performed.

MAIN OUTCOME MEASURE(S)

Immunohistochemical localization of VEGF-R proteins in oviduct tissue, and the differences of VEGF-R mRNA expression in the various regions of the oviduct and in the various stages of the ovulatory cycle.

RESULT(S)

Immunohistochemical study localized VEGF-R, both KDR and flt-1, in the oviduct luminal epithelium, smooth muscle cells as well as blood vessels within the oviduct. Messenger RNA expression of KDR, but not flt-1, was significantly higher in the ampullary and infundibular regions than in the isthmus. Messenger RNA expression of flt-1, but not KDR, varied significantly in the oviduct along the course of an ovulatory cycle, with the highest level in the periovulatory stage.

CONCLUSION(S)

These results suggest that the two VEGF receptors may have different roles in the oviduct. Our data support a role for KDR in oviduct angiogenesis whereas flt-1 appears to be important in the temporal regulation of oviductal secretion.

Expression of vascular endothelial growth factor (VEGF)-C and VEGF-D, and their receptor VEGFR-3, during different stages of cervical carcinogenesis

Cervical carcinogenesis has well-defined stages of disease progression including three grades of pre-invasive lesions--cervical intraepithelial neoplasia grades 1-3 (CIN 1-3)--and invasive cervical cancer. However, the biological properties of CIN lesions prone to develop invasive disease are not well defined. Recent observations suggest that early invasive disease spreads to regional lymph nodes in several tumour types and that growth factors (VEGF-C and VEGF-D) involved in new lymphatic vessel formation may play a crucial role in this process. The present study has assessed the expression of VEGF-C and VEGF-D, and their receptor VEGFR-3, in 152 cervical lesions (33 CIN 1, 33 CIN 2, 37 CIN 3, and 49 squamous cell carcinomas) to determine whether expression of lymphangiogenic factors occurs prior to invasion. The presence of lymphatic vessels was determined using LYVE-1 and podoplanin staining, as well as double immunostaining for LYVE-1/CD34 and podoplanin/CD34. In situ hybridization was performed to determine VEGFR-3 mRNA expression. A significant positive correlation was found between VEGF-C, VEGF-D, and VEGFR-3 expression through the different stages of cervical carcinogenesis. Significant differences in protein expression for VEGF-C, VEGF-D, and VEGFR-3 were found between CIN 1-2 and CIN 3 (p<0.001 for all), but not between CIN 3 and cervical cancer. More than 50% of the CIN 3 lesions showed moderate to strong staining for VEGF-C and VEGF-D, whereas most of the early pre-cancerous lesions (CIN 1 and 2) were negative. In cervical cancer, similar observations to those in CIN 3 were found. VEGFR-3 mRNA expression was found in the cytoplasm of epithelial neoplastic cells and VEGFR3 protein expression was found in more than 50% of CIN 3 lesions and cervical cancers, compared with 15% in CIN 1 and 2. These findings suggest an autocrine growth stimulation pattern via VEGFR-3. Adjacent CIN 3 was present in nine cervical cancers and displayed strong expression for VEGF-C, VEGF-D, and VEGFR-3. These results suggest that in cervical carcinogenesis a switch to the lymphangiogenic phenotype may occur at the stage of CIN 3.

[Prognostic significance of VEGF receptors, VEGFR-1 (Flt-1) and VEGFR-2 (KDR/Flk-1) in breast carcinoma]

OBJECTIVES

The aim of this study was to investigate the prognostic value of vascular endothelial growth factor (VEGF) receptors, VEGFR-1 (Flt-1) and VEGFR-2 (KDR/Flk-1) in breast carcinoma.

METHODS

VEGF receptor expression was investigated using immunohistochemical assays with monoclonal antibodies on frozen sections in a series of 918 patients and was correlated with prognostic parameters and with long-term follow-up (median, 11.3 years). VEGFR-1 and VEGFR-2 immunostained surface was evaluated in percentage of the total tumor specimen surface by light microscopy (x100).

RESULTS

VEGFR-1 and VEGFR-2 were strongly expressed in endothelial cells within blood microvessels, and weakly in tumor cells. Univariate (Kaplan Meier) analysis showed that VEGFR-1 positive tumor surface (cut off=5%) was not correlated with survival, but was significantly correlated with high metastasis risk (p=0.03) and relapse (p=0.01) in all patients, and in those with node negative tumors (p=0.001 and p=0.01 respectively). In multivariate analysis (Cox model), VEGFR-1 expression was identified as an independent prognostic indicator. Univariate analysis showed that VEGFR-2 positive tumor surface (cut off=10%) was not correlated with survival or with metastasis risk and relapse.

CONCLUSION

Our results show that VEGFR-1 immunohistochemical expression permits the identification of patients with poor outcome, particularly those with node negative tumors, with high risk of metastasis and relapse. VEGFR-1 immunodetection may further be considered as a potential tool for evaluating tumor agressiveness and therapeutic strategies in breast cancer.