Correlation between ERG changes and FGF2 mRNA Up-regulation in patients with choroidal melanoma

To study electroretinographic (ERG) response to light flashes in patients with choroidal melanoma and to define possible factors involved in the modification of both a- and b-wave.ISCEV standard flash-ERG was recorded from both affected and control eyes on 24 patients before surgical operation (local excision or enucleation). The choroidal melanomatous mass ranged from 33 to 2880mm(3). Tissues from both melanomatous retina-choroid complex and areas far from the melanoma (unaffected) were taken from 13 enucleated eyes to measure the level of FGF2 mRNA, utilizing the technique of semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Tissues from 10 normal eyes were used as control. The majority of patients showed a marked a- and b-wave attenuation in the affected eye with respect to the fellow eye. In 10 retinal specimens, the expression of FGF2 mRNA showed an increase in retinal regions far from the melanoma compared to control eyes. Many patients present an increase in the expression of FGF2 mRNA in the unaffected part of the retina and a clear attenuation in both a- and b-ERG components. The size of melanoma does not predict the amount of reduction in the ERG response, at least for sizes less than 1000mm(3). We suggest that the melanoma triggers a process leading to an up-regulation of FGF2 in the human eye and this up-regulation might be responsible for the ERG attenuation.

HIF-1-induced erythropoietin in the hypoxic retina protects against light-induced retinal degeneration

Erythropoietin (Epo) is upregulated by hypoxia and provides protection against apoptosis of erythroid progenitors in bone marrow and brain neurons. Here we show in the adult mouse retina that acute hypoxia dose-dependently stimulates expression of Epo, fibroblast growth factor 2 and vascular endothelial growth factor via hypoxia-inducible factor-1alpha (HIF-1alpha) stabilization. Hypoxic preconditioning protects retinal morphology and function against light-induced apoptosis by interfering with caspase-1 activation, a downstream event in the intracellular death cascade. In contrast, induction of activator protein-1, an early event in the light-stressed retina, is not affected by hypoxia. The Epo receptor required for Epo signaling localizes to photoreceptor cells. The protective effect of hypoxic preconditioning is mimicked by systemically applied Epo that crosses the blood retina barrier and prevents apoptosis even when given therapeutically after light insult. Application of Epo may, through the inhibition of apoptosis, be beneficial for the treatment of different forms of retinal disease.

Angiogenic bFGF expression from gas-plasma treated scaffolds

PURPOSE

In vivo experiments indicate that gas-plasma-treated D,L-polylactide polymers expressing basic fibroblast growth factor (bFGF) exhibit enhanced angiogenesis. bFGF is not a single entity, but it is instead a family of isoforms. Consequently, we sought to determine which bFGF isoforms and levels initiate angiogenesis in nude mice peritoneums.

METHODS

Cytoplasmic and nuclear bFGF were characterized for nude mice peritoneums incubated with nontreated scaffolds containing HAEC (CW), its respective polymer-only scaffolds (Cp) and gas-plasma treated scaffolds with HAEC (TW) and without cells (Tp). NuPAGE electrophoresis and WesternBreeze Chemiluminescent kits were used to analyze relative bFGF densities and molecular weights. VEGF was quantified using ImageJ.

RESULTS

bFGF bands were located at molecular weights of 24, 48, 58, 72 and 80 kDa, depending on whether they were from cytoplasms or nuclei. At 12, 24 and 72 days, 58-kDa bFGF bands were observed from nuclei of TW and Tp, 80-kDa bFGF bands were only observed in cytoplasmic fractions < or = 24 days. Total cytoplasmic and nuclear bFGF intensities increased from 12 to 24 days, then declined by 72 days.

CONCLUSIONS

(1) Gas-plasma treated scaffolds up-regulate bFGF isoforms. (2) bFGF was expressed in the nuclei; however, 80-kDa bFGF was seen only in cytoplasms.

Basic fibroblast growth factor autocrine loop controls human osteosarcoma phenotyping and differentiation

BACKGROUND

We focused on the phenotype of non-mineralizing MG 63 and mineralizing TE 85 human osteosarcoma cells and investigated the role of bFGF in modulating their differentiative responses. Basic FGF expression and bFGF effects on osteocalcin, runt-related transcription factor-2 (RUNX2), matrix molecular production and bFGF receptors, were evaluated.

MATERIALS AND METHODS

Osteocalcin and RUNX2 gene expression were studied by RT-PCR analysis. We evaluated cell proliferation by DNA content and performed differentiation studies on glycosaminoglican (GAG), collagen and proteoglican (PG) synthesis by using radiolabelled precursors and Northern blotting. BFGF receptors were quantified by bFGF receptor binding assay.

RESULTS

Osteocalcin is expressed in MG63 and TE65. RUNX2 RNA is differentially spliced in the two cell lines. BFGF elicits the effects of differentially splicing RUNX2. Proliferation, GAG synthesis, bFGF and proteoglycan mRNA expression, high and low affinity bFGF receptors, were more marked in MG 63 and differently affected by bFGF. Procollagen expression and alkaline phosphatase activity were significantly reduced. BFGF increased TE 85 cell proliferation and reduced TE 85 procollagen and osteocalcin production.

CONCLUSIONS

The different splice variants in RUNX2 gene in the two cell lines might be related to their different phenotypes. The less differentiated stage of MG63 could also be related to bFGF over-production and more bFGF receptors. The consequent increase in bFGF-bFGF receptor binding could explain the bFGF differentiative effects on MG 63. We suggest an autocrine role of bFGF endogenous release in controlling the different osteosarcoma phenotypes.

Frequent administration of angiogenesis inhibitor TNP-470 (AGM-1470) at an optimal biological dose inhibits tumor growth and metastasis of metastatic human transitional cell carcinoma in the urinary bladder

PURPOSE

The angiogenic inhibitor TNP-470 (AGM-1470, O-chloracetyl-carbamoyl fumagillol) has been reported to inhibit the growth of human transitional cell carcinoma (TCC) in the urinary bladder. However, it is still unknown whether TNP-470 inhibits metastasis of TCC. Here, we identify an efficient protocol using TNP-470, and optimize its antitumor and antimetastatic effects on human TCC in the urinary bladder.

EXPERIMENTAL DESIGN

In vitro, the human metastatic TCC cell line 253J B-V and human umbilical vascular endothelial cells were treated with TNP-470, and examined for cell growth and protein production of angiogenic factors. To study in vivo effects of TNP-470, 253J B-V cells were implanted orthotopically into athymic nude mice. TNP-470 was administered in several dosing and scheduling regimens, and its effects on tumor growth, metastasis, intratumor neovascularization, and mRNA expression of angiogenic factors were determined in both nonestablished and established tumors.

RESULTS

In vitro treatment with TNP-470 inhibited cell growth and production of basic fibroblast growth factor protein in 253J B-V and human umbilical vascular endothelial cells in a dose-dependent manner. In vivo daily administration of TNP-470 significantly inhibited tumor growth (P < 0.001), metastasis (P < 0.05), intratumor neovascularization (P < 0.005), and mRNA expression of basic fibroblast growth factor and MMP-9 (P < 0.005), in both nonestablished and established tumors. Increasing the daily dose did not increase the effect on tumor growth, metastasis, and angiogenesis; however, the drug-induced toxicity did increase in a dose-dependent manner.

CONCLUSIONS

Frequent administration of TNP-470 at an optimal biological dose provided maximal antitumor and antimetastatic effects of human TCC of the urinary bladder. It may function by down-regulating angiogenic factors.

Retinal glial cells stimulate microvascular pericyte proliferation via fibroblast growth factor and platelet-derived growth factor in vitro

PURPOSE

To investigate whether retinal glial cells (RGCs), which are believed to play an important role in the development and maintenance of microvessels, stimulate the proliferation of retinal bovine microvascular pericytes, an essential component of the vessels.

METHODS

Conditioned medium (CM) was collected from a primary culture of RGC obtained from chick embryonic retina. The cell number was assayed after stimulation by RGC-CM. Also, by neutralizing antibody and reverse transcription polymerase chain reaction (RT-PCR), we tried to identify which factor of the RGCs contributes to the pericyte stimulation.

RESULTS

Pericyte proliferation was stimulated by RGC-CM in a dose-dependent manner. Platelet-derived growth factor-BB (PDGF-BB), acidic fibroblast growth factor (aFGF), and basic fibroblast growth factor (bFGF) stimulated pericyte proliferation; however, PDGF-AA, transforming growth factor-beta2 (TGF-beta2), and vascular endothelial growth factor (VEGF) did not. The RGC-CM-dependent stimulative effect was blocked, in part, by the neutralizing antibodies for aFGF, bFGF, and PDGF. A mixture of these three antibodies completely blocked the stimulation. RT-PCR revealed that RNA for aFGF, bFGF, and TGF-beta2 were expressed in RGCs.

CONCLUSIONS

Pericyte growth is stimulated in vitro by RGC-CM through aFGF, bFGF, PDGF-BB, at least in part. This finding suggests that RGCs may modulate in vivo pericyte cell growth through these three growth factors.

Flow-dependent remodeling in the carotid artery of fibroblast growth factor-2 knockout mice

OBJECTIVE

Fibroblast growth factor-2 (FGF2) has been implicated as a mediator in the structural remodeling of arteries. Chronic changes in blood flow are known to cause reorganization of the vessel wall, resulting in permanent changes in artery size (flow-dependent remodeling). Using FGF2 knockout (Fgf2(-/-)) mice, we tested the hypothesis that FGF2 is required during flow-dependent remodeling of the carotid arteries.

METHODS AND RESULTS

All branches originating from the left common carotid artery (LCCA), except for the left thyroid artery, were ligated to reduce flow in the LCCA and increase flow in the contralateral right common carotid artery (RCCA). Age- and sex-matched control animals did not undergo ligation of the LCCA branches. Morphometric analysis showed that by day 7, vessel diameter was significantly greater in the high-flow RCCA of FGF2 wild-type (Fgf2(+/+)) and Fgf2(-/-) mice versus the respective control RCCA, demonstrating outward remodeling. In contrast, vessel diameter was decreased by day 7 in the low-flow LCCA of both genotypes compared with the control LCCA, showing inward remodeling. No differences were observed between Fgf2(+/+) and Fgf2(-/-) mice in either high-flow or low-flow remodeling.

CONCLUSIONS

Given these results, we demonstrate that FGF2 is not essential for flow-dependent remodeling of the carotid arteries.

[Effect of naoyi'an on basic fibroblastic growth factor mRNA expression and tumor necrosis factor protein expression in brain of rats following intracerebral hemorrhage]

OBJECTIVE

To investigate the effect of Naoyi'an granule (NYAG) on basic fibroblastic growth factor (bFGF) mRNA expression and tumor necrosis factor (TNF) protein expression following intracerebral hemorrhage and provide the theoretical evidence of NYAG in treating intracerebral hemorrhage and promoting the rehabilitation of neural function.

METHODS

Model rats of intracerebral hemorrhage induced by infusion of collagenase VII into the caudate-putamen were used to determine the related parameters of behavior scores (BS), Northern blot, Western blot assay and optical density (OD) scanning in the model and the model treated with NYAG. And the data got from the two groups were compared.

RESULTS

BS in the model group began to lower 24 hrs after modeling and a significant decrease was shown 7 days later, while in the NYAG group, it decreased significantly three days after modeling, the difference between the two groups was significant (P < 0.05). Levels of bFGF mRNA expression and TNF protein expression increased after modeling, it reached the peak in three days and began to decrease gradually in seven days in both groups. However, the level in the NYAG group was higher than that in the model group in various times of the experimental process.

CONCLUSION

NYAG could enhance the bFGF expression and suppress the TNF expression so as to improve the behavior deficit in treating intracerebral hemorrhage, which may be one of the main mechanisms of NYAG for promoting the rehabilitation of neural function.

TGF-beta1 regulates TGF-beta1 and FGF-2 mRNA expression during fibroblast wound healing

AIMS

To evaluate the expression of transforming growth factor beta1 (TGF-beta1) and fibroblast growth factor 2 (FGF-2) mRNA in stromal cells in response to injury in the presence of either TGF-beta1 or FGF-2. It has been shown previously that heparan sulfate proteoglycans and FGF-2 are present transiently during wound repair in vivo and that an increase in TGF-beta1 mRNA is detected rapidly after injury.

METHODS

Primary corneal fibroblasts were cultured to confluency, serum starved, and linear wound(s) were made in medium containing TGF-beta1 or FGF-2. TGF-beta1 and FGF-2 mRNA expression were evaluated using both northern blot analysis and in situ hybridisation. Both dose dependent and time course experiments were performed. Whole eye organ culture experiments were also carried out and growth factor expression was assessed.

RESULTS

Injury and exogenous TGF-beta1 increased TGF-beta1 mRNA values. The increase in expression of FGF-2 mRNA was not detected until wound closure. In contrast, FGF-2 inhibited the expression of TGF-beta1. TGF-beta1 increased TGF-beta1 mRNA stability but did not alter that of FGF-2. Migration assay data demonstrated that unstimulated stromal cells could be activated to migrate to specific growth factors.

CONCLUSIONS

TGF-beta1 specifically enhances cellular responsiveness, as shown by increased stability after injury and the acquisition of a migratory phenotype. These data suggest that there is an integral relation during wound repair between TGF-beta1 and FGF-2.

Neurotrophic factor receptors in epiretinal membranes after human diabetic retinopathy

OBJECTIVE

Formation of epiretinal membranes (ERMs) in the posterior fundus results in progressive deterioration of vision. ERMs have been associated with numerous clinical conditions, including proliferative diabetic retinopathy (PDR), but its pathogenic mechanisms are still unknown. This study was conducted to determine whether neurotrophic factor receptors (tyrosine kinase receptors trkA, trkB, and trkC; low-affinity neurotrophin [NT] receptor p75 [p75(NTR)]; glial cell line-derived neurotrophic factor receptor-alpha1 [GFR alpha 1] and GFR alpha 2; and Ret) are involved in the formation of ERMs after PDR.

RESEARCH DESIGN AND METHODS

ERM samples were obtained by vitrectomy from 19 subjects with PDR aged 57 +/- 8 years with 17 +/- 8 years of diabetes and 15 subjects with idiopathic ERM. They were processed for RT-PCR analysis. In addition, 11 ERM samples from PDR patients aged 47 +/- 18 years with 13 +/- 4 years of diabetes were processed for immunohistochemical analysis.

RESULTS

Expressions of trkA, trkB, trkC, p75(NTR), and Ret mRNAs were similar in both groups. In contrast, GFR alpha 2 expression levels were significantly higher (17 of 19 vs. 2 of 15 subjects in idiopathic ERM, P < 0.0001) in PDR subjects. Accordingly, immunohistochemical analysis revealed expression of GFR alpha 2 protein in all of the 11 ERMs derived from PDR patients, and that region was double-labeled with glial cell-specific markers. On the other hand, GFR alpha 1 expression was lower (8 of 19 vs. 12 of 15 subjects with idiopathic ERM, P = 0.0258) in PDR subjects.

CONCLUSIONS

These results suggest a possibility that glial cell line-derived neurotrophic factor receptor (GDNF) subtypes are differently involved in the formation of ERMs.

The prognostic value of angiogenesis and metastasis-related genes for progression of transitional cell carcinoma of the renal pelvis and ureter

PURPOSE

We reported previously that angiogenesis evaluated by intratumor microvessel density (MVD), expression of such angiogenic factors as vascular endothelial cell growth factor (VEGF) and basic fibroblast growth factor (bFGF), and the matrix metalloproteinase-9:E-cadherin ratio (M:E ratio) could identify patients with advanced transitional cell carcinoma (TCC) of the bladder for whom chemotherapy and cystectomy will be unsuccessful. In the present study, we evaluated the significance of the M:E ratio as a predictor for prognosis for patients with TCC in the upper urinary tract (TCC-UUT).

EXPERIMENTAL DESIGN

We evaluated MVD by immunohistochemistry and the expression of angiogenic and metastasis-related factors by in situ hybridization in 55 nephroureterectomy specimens from patients who received no neoadjuvant therapy. The expression of angiogenesis, angiogenic and metastasis-related factors, and clinicopathological characteristics were evaluated for their correlation with metastasis, recurrence, and disease prognosis.

RESULTS

We found that tumor grade and pathological stage were important predictors for metastasis and survival in these patients. The expression level of matrix metalloproteinase type 9 (MMP-9) and type 2 (MMP-2) and the M:E ratio correlated with MVD. Increased MVD, elevated expression levels of MMP-9 and MMP-2, and a higher M:E ratio were associated with poor prognosis. Moreover, lower expression levels of E-cadherin were associated with fewer recurrences in the urinary bladder. Multivariate analysis indicated that the M:E ratio and E-cadherin expression were independent prognostic factors for disease progression and intravesical recurrence, respectively.

CONCLUSION

We suggest that the M:E ratio and E-cadherin expression may be targets for novel therapeutic strategies.

Angiogenic gene therapy for experimental critical limb ischemia: acceleration of limb loss by overexpression of vascular endothelial growth factor 165 but not of fibroblast growth factor-2

Recent studies suggest the possible therapeutic effect of intramuscular vascular endothelial growth factor (VEGF) gene transfer in individuals with critical limb ischemia. Little information, however, is available regarding (1) the required expression level of VEGF for therapeutic effect, (2) the related expression of endogenous angiogenic factors, including fibroblast growth factor-2 (FGF-2), and (3) the related adverse effects due to overexpression of VEGF. To address these issues, we tested effects of overexpression of VEGF165 using recombinant Sendai virus (SeV), as directly compared with FGF-2 gene transfer. Intramuscular injection of SeV strongly boosted FGF-2, resulting in significant therapeutic effects for limb salvage with increased blood perfusion associated with enhanced endogenous VEGF expression in murine models of critical limb ischemia. In contrast, VEGF165 overexpression, 5-times higher than that of baseline on day 1, also strongly evoked endogenous VEGF in muscles, resulting in an accelerated limb amputation without recovery of blood perfusion. Interestingly, viable skeletal muscles of either VEGF165- or FGF-2-treated ischemic limbs showed similar platelet-endothelial cell adhesion molecule-1-positive vessel densities. Maturation of newly formed vessels suggested by smooth muscle cell actin-positive cell lining, however, was significantly disturbed in muscles with VEGF. Further, therapeutic effects of FGF-2 were completely diminished by anti-VEGF neutralizing antibody in vivo, thus indicating that endogenous VEGF does contribute to the effect of FGF-2. These results suggest that VEGF is necessary, but should be delicately regulated to lower expression to treat ischemic limb. The therapeutic effect of FGF-2, associated with the harmonized angiogenic effects seen with endogenous VEGF, provides important insights into therapeutic angiogenesis.

Delivery of FGF genes to wound repair cells enhances arteriogenesis and myogenesis in skeletal muscle

Tissue repair is driven by migratory macrophages and fibroblasts that infiltrate injury sites and secrete growth factors. We now report the enhancement of skeletal muscle repair by targeting transgene delivery to these repair cells using matrix-immobilized gene vectors. Plasmid and adenovirus vectors immobilized in collagen-gelatin admixtures were delivered to excisional muscle wounds, and when encoding either fibroblast growth factor-2 (FGF2) or FGF6 transgenes, produced early angiogenic responses that subsequently remodeled into arteriogenesis. FGF2 gene delivery enhanced the number of CD31(+) endothelial cells present at treatment sites > 6-fold by day 14, and muscular arteriole density up to 11-fold by day 21 (P<0.0001). Muscle repair was also enhanced, as FGF gene-treated wounds filled with regenerating myotubes expressing the marker CD56 (an average 20-fold increase in CD56 expression versus controls, P<0.0001). These responses required transfection of a threshold level of repair cells, achievable only in injured muscles, and were transgene-driven, as neither platelet-derived growth factor-B (PDGFB) gene nor FGF2 protein delivery produced equivalent responses. In conclusion, using biomatrices to direct gene delivery to repair cells allows for relatively complex regenerative processes such as arteriogenesis and myogenesis, and therefore represents a promising approach to treating injured and ischemic muscle.

Concomitant expression of heparin-binding epidermal growth factor-like growth factor mRNA and basic fibroblast growth factor mRNA in myocardial infarction in rats

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is mitogenic and chemotactic for many cell types. HB-EGF is induced in pathological states which require cell mitogenesis and proliferation, including angiogenesis, and has been reported to interact functionally with basic fibroblast growth factor (bFGF). To test our hypothesis that HB-EGF mRNA expression is increased in myocardial infarction, we used Northern hybridization in rats to investigate the expression of HB-EGF and EGF receptor mRNAs expression in the infarct zone compared to the expression of bFGF and FGF receptor mRNAs. We also performed in situ hybridization to identify the cells responsible for HB-EGF mRNA production. HB-EGF mRNA rapidly increased after ligation (mean +/- SE, 5.6+/-0.23-fold increase at 6 hours compared to the preligation heart levels) and reached a maximum level (9.1+/-0.42-fold increase) around 12 hours. HB-EGF mRNA then gradually decreased on day 1 (5.8+/-1.0-fold increase), day 2 (3.2+/-0.94-fold increase) and day 3 (1.9+/-0.33-fold increase) after ligation. Parallel changes in bFGF mRNA expression were observed (6, 12 hours, days 1, 2 and 3; 3.6+/-0.42-, 5.3+/-0.12-, 2.3+/-0.12-, 1.7+/-0.03- and 0.95+/-0.03-fold increase, respectively). EGF receptor (ErbB-1) mRNA was gradually increased on day 2 (2.4+/-0.53-fold increase), day 7(4.0+/-0.61-fold increase) and day 14 (7.0+/-0.61-fold increase). Similarly, FGF receptor (FGF receptor-1) mRNA was gradually increased (days 2,7 and 14; 1.3+/-0.13-, 1.5+/-0.17- and 2.3+/-0.15-fold increase, respectively). Reperfusion after a 2-hour ligation (too late to salvage myocytes) enhanced HB-EGF (12 hours, 16.8+/-1.8-fold increase) and bFGF (12 hours, 10.4+/-1.1-fold increase) mRNA expression. The cells responsible for the increased production of HB-EGF mRNA were shown by in situ hybridization to be surviving myocytes located in the infarct peripheral zone around infarct necrotizing tissue. In conclusion, our results demonstrated a rapid increase in HB-EGF mRNA expression concomitant with an increase in bFGF mRNA expression, suggesting that HB-EGF and bFGF might play some role in the course of pathological changes in the infarct in the early inflammatory phase. Reperfusion at times too late to salvage myocytes accelerated sequential changes in the expression of both HB-EGF and bFGF mRNAs.

[Losartan in the rat model of bleomycin-induced pulmonary fibrosis and its impact on the expression of monocyte chemoattractant protein-1 and basic fibroblast growth factor]

OBJECTIVE

To study the effect of losartan on bleomycin-induced pulmonary fibrosis in rats and its possible mechanism.

METHODS

Pulmonary fibrosis was induced in Wistar rats by intratracheal instillation of bleomycin. Then the rats received daily losartan 10 mg/kg (group L), prednisone 20 mg/kg (group P), or normal saline (group B) orally. Normal controls received normal saline both intratracheally and orally. Six rats in each group were sacrificed 3, 7, 14, 28 and 56 days after intratracheal instillation. Histological changes of the lungs were evaluated by HE stain, Masson's trichrome stain and sirius red stain. Collagen content of the lung tissue was assessed by hydroxyproline concentration. The mRNAs of monocyte chemoattractant protein-1 (MCP-1) and basic fibroblast growth factor (bFGF) were detected by reverse transcription-polymerase chain reaction (RT-PCR). Lung expression of MCP-1 and bFGF proteins was assessed by immunohistochemistry and the level of MCP-1 protein was further measured by ELISA.

RESULTS

Pulmonary fibrosis of group L and group P was improved as compared with that of group B. Hydroxyproline concentrations of group L and group P were lower than that of group B. Protein expression of MCP-1 and bFGF in group L was lower than that in group B.

CONCLUSION

Losartan alleviates bleomycin-induced pulmonary fibrosis in rats. Inhibiting the expressions of MCP-1 and bFGF in lung tissues may be one of the mechanisms.

Toward pathogenesis of Apert cleft palate: FGF, FGFR, and TGF beta genes are differentially expressed in sequential stages of human palatal shelf fusion

OBJECTIVE

Critical cellular events at the palatal medial edge epithelium (MEE) occur in unperturbed mammalian palatogenesis, the molecular control of which involves a number of growth factors including transforming growth factor beta 3 (TGF beta 3). Apert syndrome is a monogenic human disorder in which cleft palate has been significantly correlated to the fibroblast growth factor receptor (FGFR) 2-Ser252Trp mutation. We report the relative expression of these genes in human palatogenesis.

METHODS

The expression of the IgIIIa/b and IgIIIa/c transcript isoforms of FGFR2 and the proteins FGFR1, FGFR2, and FGFR3 was studied in situ throughout the temporospatial sequence of human palatal shelf fusion and correlated with the expression of TGF beta 3. In addition, the immunolocalization of the ligand FGFs 2, 4, and 7 was undertaken together with the intracellular transcription factor STAT1, which is activated by FGFR signaling.

RESULTS

FGFRs are differentially expressed in the mesenchyme and epithelia of fusing palatal shelves, in domains overlapping those of their ligands FGF4 and FGF2 but not FGF7. Coexpression is seen with TGF beta 3, which is implicated in MEE dynamics and FGF and FGFR upregulation, and STAT1, an intracellular transcription factor that mediates apoptosis.

CONCLUSIONS

The coregulation of molecules of the FGFR signaling pathway with TGF beta 3 throughout the stages of human palatal fusion suggests their controlling influence on apoptosis and epitheliomesenchymal transdifferentiation at the MEE. Experimental evidence links FGFR2-IgIIIa/b loss of function with palatal clefting, and these correlated data suggest a unique pathological mechanism for Apert cleft palate.

Regulation of telomerase activity in rat lung fibroblasts

Fibroblasts from bleomycin-injured lungs express telomerase activity transiently during the period of active fibrosis, but the signal(s) responsible for its induction is (are) unknown. The objective of this study was to identify potential mediators capable of regulating telomerase activity induction in rat lung fibroblasts during pulmonary fibrosis. Lung fibroblasts from control (NRF) and bleomycin-treated (BRF) rats were isolated and treated in vitro with either basic fibroblast growth factor (bFGF) or interleukin-4 (IL-4). At selected time points after treatment, the cells were analyzed for telomerase activity, as well as telomerase reverse transcriptase (TERT) mRNA and protein by reverse transcriptase/polymerase chain reaction and Western blot, respectively. The results showed that bFGF could induce telomerase activity in NRF and stimulate further the induced activity in BRF. The bFGF effect was accompanied by increased TERT protein expression and a rapid but transient increase in TERT mRNA. In contrast, IL-4 inhibited the induced telomerase activity in BRF, which was accompanied by increased alpha-smooth muscle actin expression, an indicator of myofibroblast differentiation. These findings suggest that telomerase expression could be induced in rat lung fibroblasts by bFGF, but suppressed by IL-4, which promoted myofibroblast differentiation. The latter is consistent with the preferential expression of telomerase activity in fibroblasts relative to myofibroblasts.

Human T-cell lymphotropic virus type 1-transformed cells induce angiogenesis and establish functional gap junctions with endothelial cells

The role of angiogenesis in the growth and metastasis of solid tumors is well established. However, the role of angiogenesis in hematologic malignancies was only recently appreciated. We show that HTLV-I-transformed T cells, but not HTLV-I-negative CD4(+) T cells, secrete biologically active forms of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) and, accordingly, induce angiogenesis in vitro. Furthermore, fresh ATL leukemic cells derived from patients with acute ATL produce VEGF and bFGF transcripts and proteins. The viral transactivator Tax activates the VEGF promoter, linking the induction of angiogenesis to viral gene expression. Angiogenesis is associated with the adhesion of HTLV-I-transformed cells to endothelial cells and gap junction-mediated heterocellular communication between the 2 cell types. Angiogenesis, cell adhesion, and communication likely contribute to the development of adult T-cell leukemia-lymphoma and represent potential therapeutic targets.

Enhanced neuroprotective effects of basic fibroblast growth factor in regional brain ischemia after conjugation to a blood-brain barrier delivery vector

Basic fibroblast growth factor (bFGF) has minimal pharmacological effects in the central nervous system in the absence of blood-brain barrier (BBB) disruption. BBB transport of bFGF occurs via an absorptive-mediated transcytosis mechanism, which is relatively inefficient. To enhance the BBB transport of bFGF, this neurotrophin was reformulated to enable receptor-mediated transport across the BBB via the transferrin receptor. bFGF was monobiotinylated and coupled to a BBB drug-delivery vector comprised of streptavidin (SA) and the OX26 monoclonal antibody to the rat transferrin receptor. The entire conjugate of biotinylated bFGF bound to the OX26-SA is designated bio-bFGF/OX26-SA. The bFGF retains receptor-binding affinity and has increased brain uptake following conjugation to OX26-SA. The bio-bFGF/OX26-SA conjugate protects cortical cell cultures against hypoxia/reoxygenation insult in a dose-dependent manner in vitro. A single intravenous injection of bio-bFGF/OX26-SA, equivalent to a dose of 25 microg/kg bFGF, produces an 80% reduction in infarct volume in the brain of rats subjected to permanent occlusion of the middle cerebral artery in parallel with a significant improvement of neurologic deficit. The neuroprotection is time-dependent, and there is a 67% reduction in stroke volume if the conjugate is administered at 60 min after arterial occlusion, whereas no significant reduction in stroke volume is observed if treatment is delayed 2 h. In conclusion, neuroprotection in regional brain ischemia is possible following the delayed intravenous injection of low doses of bFGF providing the neurotrophin is conjugated to a BBB drug-targeting system.

Cyclic mechanical stretch induces VEGF and FGF-2 expression in pulmonary vascular smooth muscle cells

Vascular endothelial growth factor (VEGF) and basic (b) fibroblast growth factor (FGF-2/bFGF) are involved in vascular development and angiogenesis. Pulmonary artery smooth muscle cells express VEGF and FGF-2 and are subjected to mechanical forces during pulsatile blood flow. The effect of stretch on growth factor expression in these cells is not well characterized. We investigated the effect of cyclic stretch on the expression of VEGF and FGF-2 in ovine pulmonary artery smooth muscle cells. Primary confluent cells from 6-wk-old lambs were cultured on flexible silicon membranes and subjected to cyclic biaxial stretch (1 Hz; 5-25% stretch; 4-48 h). Nonstretched cells served as controls. Expression of VEGF and FGF-2 was determined by Northern blot analysis. Cyclic stretch induced expression of both VEGF and FGF-2 mRNA in a time- and amplitude-dependent manner. Maximum expression was found at 24 h and 15% stretch (VEGF: 1.8-fold; FGF-2: 1.9-fold). These results demonstrate that mechanical stretch regulates VEGF and FGF-2 gene expression, which could play a role in pulmonary vascular development or in postnatal pulmonary artery function or disease.

Endothelin-1, an important mitogen of smooth muscle cells of spontaneously hypertensive rats

OBJECTIVE

To study the features of vascular smooth muscle cell (VSMC) proliferation induced by endothelin-1 (ET-1).

METHODS

VSMCs of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats were cultured and treated with ET-1. Basic fibroblast growth factor (bFGF) gene expression was measured using both Northern blot and an enzyme-linked immunoassay.

RESULTS

ET-1 resulted in an increase in bFGF transcripts at 8 - 24 h; bFGF levels were significantly higher in VSMCs treated with ET-1 than in those not treated. However, VSMCs growth responses in SHR and WKY were different. Smooth muscle cells of SHR were hyper-responsive to ET-1. Maximal bFGF mRNA levels were elevated 3.5-fold at 4 h of stimulation in WKY and 8-fold at 8h in SHR4. Moreover, the proliferation of VSMCs induced by ET-1 was inhibited by antisense phosphorothioate oligodeoxynucleotides (10 micromol/L AS-bFGF) but not sense bFGF oligomers at the same concentrations, being reduced by 80% in SHR and 40% in WKY vs control, respectively. Furthermore, the effect of AS-bFGF oligomers on SHR SMC proliferation is significantly greater than on WKY SMC proliferation.

CONCLUSION

ET-1 may be required for exaggerated vascular growth responses in SHR and bFGF may be involved.

Integrative nuclear FGFR1 signaling (INFS) pathway mediates activation of the tyrosine hydroxylase gene by angiotensin II, depolarization and protein kinase C

The integrative nuclear FGFR1 signaling (INFS) pathway functions in association with cellular growth, differentiation, and regulation of gene expression, and is activated by diverse extracellular signals. Here we show that stimulation of angiotensin II (AII) receptors, depolarization, or activation protein kinase C (PKC) or adenylate cyclase all lead to nuclear accumulation of fibroblast growth factor 2 (FGF-2) and FGFR1, association of FGFR1 with splicing factor-rich domains, and activation of the tyrosine hydroxylase (TH) gene promoter in bovine adrenal medullary cells (BAMC). The up-regulation of endogenous TH protein or a transfected TH promoter-luciferase construct by AII, veratridine, or PMA (but not by forskolin) is abolished by transfection with a dominant negative FGFR1TK-mutant which localizes to the nucleus and plasma membrane, but not by extracellularly acting FGFR1 antagonists suramin and inositolhexakisphosphate (IP6). Mechanism of TH gene activation by FGF-2 and FGFR1 was further investigated in BAMC and human TE671 cultures. TH promoter was activated by co-transfected HMW FGF-2 (which is exclusively nuclear) but not by cytoplasmic FGF-1 or extracellular FGFs. Promoter transactivation by HMWFGF-2 was accompanied by an up-regulation of FGFR1 specifically in the cell nucleus and was prevented FGFR1(TK-) but not by IP6 or suramin. The TH promoter was also transactivated by co-transfected wild-type FGFR1, which localizes to both to the nucleus and the plasma membrane, and by an exclusively nuclear, soluble FGFR1(SP-/NLS) mutant with an inserted nuclear localization signal. Activation of the TH promoter by nuclear FGFR1 and FGF-2 was mediated through the cAMP-responsive element (CRE) and was associated with induction of CREB- and CBP/P-300-containing CRE complexes. We propose a new model for gene regulation in which nuclear FGFR1 acts as a mediator of CRE transactivation by AII, cell depolarization, and PKC.

Gene expression profile in fibroblast growth factor 2-transformed endothelial cells

Fibroblast growth factor-2 (FGF2) exerts paracrine and autocrine functions on endothelial cells. FGF2-overexpressing murine aortic endothelial cells (FGF2-T-MAE cells) induce opportunistic hemangioendothelioma-like tumors when inoculated in immunodeficient mice. To evaluate the impact of FGF2-mediated activation on gene expression profile in transformed endothelial cells, we performed subtractive suppression hybridization analysis between FGF2-T-MAE cells and parental MAE cells. The two cell populations were compared for differential gene expression also by gene macroarray hybridization with 32P-labeled cDNAs. The two approaches allowed the identification of 27 transcripts whose expression was upregulated by FGF2 in endothelial cells. With the exception of one unknown gene, the differentially expressed transcripts encoded for proteins involved in the modulation of cell cycle, differentiation, and cell adhesion. Among them, the stress-inducible genes A170, GADD45 and GADD153 are upregulated by FGF2 transfection or recombinant growth factor treatment. Their expression was also induced in vascular tumors originated by parental or FGF2-transfected MAE cells in nude mice. This study extends the number of genes involved in tumor angiogenesis and/or endothelial cell transformation, a finding with possible implications for the discovery of novel targets for angiostatic therapy.

Overexpression of basic fibroblast growth factor and Bcl-xL with adenoviral vectors protects primarily cultured neurons against glutamate insult

OBJECTIVE

Excitatory amino acid (EAA) toxicity seems to be an important mechanism of neuronal cell death after cerebral infarction. We examined the inhibitory effects of neuronal cell death caused by EAA in vitro by means of adenoviral gene transfer of neurotrophic basic fibroblast growth factor (bFGF) and antiapoptotic Bcl-xL.

METHODS

Recombinant adenoviral vectors expressing human bFGF gene with secretory signals of interleukin-2 and human Bcl-xL gene were constructed. Primarily cultured rat neuronal cells were treated with glutamate to cause EAA, and the neuroprotective effects of gene transfer by these adenoviral vectors were investigated at several time points of infection.

RESULTS

Each adenoviral infection to primarily cultured neuronal cells exhibited neuroprotective effects against EAA caused by glutamate. Both gene transfer of bFGF with secretory signal and Bcl-xL transfer to neuronal cells exhibited the synergistic neuroprotective effects against EAA. These effects were most prominent with gene transfer 4 hours before glutamate insult; gene transfer performed simultaneously with and up to 4 hours after the insult exhibited definite neuroprotective effects.

CONCLUSION

These experiments revealed marked neuroprotective effects of adenoviral gene transfer of bFGF and Bcl-xL into neuronal cells in vitro. The findings may lead to new approaches for treating occlusive cerebrovascular disease.