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Extracellular FGF-1 inhibits cytoskeletal organization and promotes fibroblast motility.

Previous efforts from this laboratory have established that acidic fibroblast growth factor (FGF-1), either added exogenously or secreted as a biologically active protein, induces a transformed phenotype in primary murine fibroblasts. Experimental studies described here demonstrate that constitutive exposure to extracellular FGF-I results in reduced cell attachment to multiple ligands, inhibition of cytoskeletal organization, and reduced collagen contraction, despite no detectable change in integrin cell surface expression. In addition, FGF-1-transduced fibroblasts demonstrated a > 10-fold increase in migration, an observation correlated with increased tyrosine phosphorylation of p125FAK and p130CAS. Collectively, these results suggest that FGF-1-induced fibroblast transformation includes the involvement of specific FGF receptor-mediated signal transduction cascades targeted to cytoskeletal and focal adhesion structures.

Animals↗

Stimulation of angiogenesis by FGF-1 delivered through a modified fibrin scaffold.

A few studies have indicated that repeated dosing of acidic fibroblast growth factor (FGF-1) is essential to be effective in modulating the wound-healing response. However, little investigation has been done to determine the effective dosing regimen of FGF-1 or the appropriate carrier vehicle for this growth factor. The main objective of this study was to determine the effective angiogenic stimulatatory dose of FGF-1 delivered through a modified fibrin matrix, using a rabbit ear ulcer model. Specifically, the aim was to test the effects of FGF-1 on the angiogenic, fibroblastic, and epithelial responses in a wound model. Five 6-mm diameter ulcers to the depth of bare cartilage were created on each rabbit ear. Four different combinations (0.8, 8, 80, and 800 micrograms/ml) of the growth factor were examined across two periods of study. Pooled modified fibrin was used to deliver the growth factor. Histomorphometrical quantification was conducted after routine histological processing of the ulcers sites. Data analysis indicated a strong correlation between concentration and the histomorphometric response. In general, the growth factor treatments affected the healing response and exhibited a dose-dependent behavior. The addition of FGF-1 led to an increase in the angiogenic and fibroblastic responses, as well as an increase in the epithelialization rate. The preferred dose of 8 micrograms initiated a high epithelialization rate, fibroblastic, and angiogenic responses, and was the lowest dose required to initiate these responses.

Animals↗

Sequence analysis of the transcription control region upstream of the human FGF-3 gene.

With the purpose of studying the transcriptional regulation of the human FGF-3 gene, we have cloned and determined the nucleotide sequence of the 11-kbp region flanking its 5' end. Analysis of the sequence disclosed the presence of multiple repetitive elements. Remarkably, all of them were found to have inserted in the same orientation as the FGF-3 gene, suggesting that the whole upstream region could play a role in the control of its transcription. Unique regions within the sequence were scanned for the presence of transcriptional regulatory elements. A potential "Initiator" sequence preceded by several motifs homologous to binding sites for transcription factors pinpointed a putative promoter, 6 kbp upstream of the ATG codon for the FGF-3 protein. A 250-nt sequence stretch surrounding the "Initiator" was found to display punctate homology with the first (P1) of the three promoters (P1, P2 and P3) of the mouse Fgf-3/int-2 gene, specifically in the region of the transcriptional start sites. These data should be useful in studying the mechanisms of regulation of the FGF-3 transcription unit.

Animals↗

FGF-2 dependent angiogenesis is a latent phenotype in basic fibroblast growth factor transgenic mice.

Overexpression of basic fibroblast growth factor (FGF-2) in transgenic (TgFGF2) mice results in a chondrodysplasia as the principle phenotype. Here we report a second phenotype in TgFGF2 mice that was previously undetected: A predisposition to angiogenic reactions with subsequent amplified angiogenesis that are both FGF-2 dependent. We used subcutaneous injection of extracellular matrix as an angiogenic assay. The matrix formed vascularized cysts in the TgFGF2 group after seven days, whereas the non-transgenic (NTg) group developed avascular cysts. Cysts from the TgFGF2 group contained 3-7X more hemoglobin (Hb), two-fold more vonWillebrand Factor (VWF), and 150X more FGF-2 than cysts from the NTg control group. Significant angiogenic reactions occurred only in the TgFGF2 group that express FGF-2 from the transgene. The TgFGF2 mice, therefore, constitute a unique experimental system to study FGF-2 dependent angiogenesis because they have no spontaneous or inherent vascular defects, but provision of an angiogenic substrate results in an amplified angiogenic response. In addition, we report development of an ELISA for VWF that provides a sensitive, quantitative assay for angiogenesis.

Animals↗

Alpha 2 beta 1 integrin is required for the collagen and FGF-1 induced cell dispersion in a rat bladder carcinoma cell line.

We have investigated the role of integrins in the epithelial to mesenchymal transition (EMT) induced by either collagen or fibroblast growth factor-1 (FGF-1) in the rat bladder carcinoma cell line NBT-II. The major collagen-binding receptor is the alpha 2 beta 1 integrin. An increase in expression of alpha 2 beta 1 integrin coincided with EMT induced by either collagen or FGF-1. When both inducers were present, a further increase in alpha 2 expression was observed which correlated with an enhancement in the speed of locomotion. Overexpression of human alpha 2 in NBT-II cells did not trigger EMT but rendered cells more sensitive to the dispersing effect of collagen and FGF-1. Anti-human alpha 2 blocking antibodies affected cell scattering and motility induced by either collagen or FGF-1. These data demonstrate that alpha 2 beta 1 integrin is the mediator of the cell scattering effect induced by collagen. They also indicate that a functional alpha 2 integrin is essential for the motile behavior of NBT-II cells during the FGF-1 induced EMT.

Animals↗

[Expression of FGF-b and C-myc in rats lung tissue affected by hypoxia].

OBJECTIVE: To study FGF's roles in the reconstruction of vascular walls owing to chronic hypoxia. METHOD: 40 SD rats [corrected] were divided into different hypoxia groups and proceeded with various hypoxic intervals. Expression of FGF-b and transcription of c-myc mRNA of the rats [corrected] lung tissues were detected by immunohistochemical method and in situ hybridization. RESULTS: FGF-b increased obviously in the smooth muscle and advential tissue of pulmonary arteries after 14 days of hypoxia, whereas C-myc mRNA showed overexpression in rats [corrected] lung tissue from 7th to 21st day of hypoxia. CONCLUSION: (1) Hypoxia may lead to activation of C-myc oncogene and increase of FGF-b expression in lung tissue. (2) FGF-b and C-myc oncogene takes part in reconstruction of pulmonary arterial wall affected by chronic hypoxia.

Animals↗

FGF: an autocrine regulator of human lens cell growth independent of added stimuli.

PURPOSE: Posterior capsule opacification (PCO) arises because of a persistent growth of lens epithelial cells. Cultured human lens cells residing on their native collagen capsule and maintained in serum-free medium actively grow and thus show an intrinsic capacity for regulation. In the present study, the authors investigated the role of the putative FGF autocrine system in human capsular bags. METHODS: Capsular bags were prepared from human donor eyes and maintained in a 5% CO(2) atmosphere at 35 degrees C. On-going observations were by phase-contrast microscopy. Cellular architecture was examined by fluorescence cytochemistry. De novo protein synthesis was determined by the incorporation of 35S-methionine. Basic fibroblast growth factor (FGF) and FGF receptor (R)-1 were detected using enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) techniques. FGFR-1 inhibition was achieved using the specific antagonist SU5402. RESULTS: Human lens epithelial cells can maintain metabolic activity for more than 1 year in a protein-free medium. Basic FGF was shown to be present in capsular bags throughout culture and also in capsular bags removed from donor eyes that had previously undergone cataract surgery. Furthermore, FGFR-1 was identified. Inhibition of FGFR-1 caused a significant retardation of growth on the posterior capsule. On no occasion did any treated bag reach confluence, whereas all match-paired control samples did. CONCLUSIONS: The results provide evidence that FGF plays an integral role in the long-term survival and growth of human lens epithelial cells, independent of external stimuli. Inhibition of FGFR-1 by specific synthetic molecules, such as SU5402, could provide a potential therapeutic approach to resolving PCO.

Autocrine Communication↗

Angiogenic factors: vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF) are not necessarily elevated in patients with advanced renal cell carcinoma.

Serum analysis of Vascular Endothelial Growth Factor (VEGF) and basic Fibroblast Growth Factor (b-FGF) levels were studied in 53 patients with renal cell carcinoma (RCC). Approximately 2/3 of the patients had disseminated disease at diagnosis, the remainder had no evidence of metastases. The results confirmed that VEGF has a major role in the angiogenesis of RCC. No correlation was observed between VEGF and/or b-FGF and the presence or absence of metastases, nor was any correlation observed between VEGF and/or b-FGF and patient survival. Thus, to utilise VEGF and/or b-FGF as a tumour marker at the time of diagnosis to predict patients with a high risk of progression, where an adjuvant therapeutic approach would be of great value, seems to be limited. Not all patients with RCC exhibited elevated serum levels of VEGF and/or b-FGF. No correlation was observed between tumour stage and serum levels of these angiogenic peptides.

Adult↗

Antitumor activity of fibroblast growth factors (FGFs) for medulloblastoma may correlate with FGF receptor expression and tumor variant.

Members of the fibroblast growth factor (FGF) family, which normally control cerebellar neuronal maturation, may represent more natural and less toxic tools with which to target medulloblastoma (MB), an embryonal brain tumor thought to arise from cerebellar neuronal precursors. In support of this, we found previously basic FGF/FGF-2 can inhibit MB progression by inducing neuronal-like differentiation, slowing the growth, and triggering apoptosis of a MB cell line we established from a histopathologically classic tumor (R. L. Kenigsberg et al., Am. J. Pathol., 151: 867-881, 1997). In the present study, the usefulness of this approach is additionally investigated. We report that of the five FGFs found in the developing cerebellum, only two, FGF-2 and FGF-9, possess antitumoral activity for MB. This activity is only noted for cell lines that originate from classic (UM-MB1 and SYR) rather than desmoplastic (HSJ) tumors. Whereas these FGFs inhibit proliferation of both classic cell lines, they only advance neuronal differentiation and induce apoptosis of one, UM-MB1. Consistent with these responses, after FGF treatment, levels of neurofilaments and the proapoptotic modulator Bax only increase in UM-MB1, whereas the cyclin-dependent kinase inhibitor p27/Kip1 (p27), which accumulates in cerebellar neuronal precursors before they exit the cell cycle, goes up in both UM-MB1 and SYR. Finally, although the histological variant of MB may help predict the sensitivity of MB to the FGFs, the selectivity, specificity, and type of response elicited may be dictated by, as evident by immunoprecipitation and Western blot analyses, the expression of certain FGF receptor types.

Animals↗

Complexity of FGF receptors: genetic basis for structural diversity and functional specificity.

Since 1989, the receptors for fibroblast growth factors (FGFs) were cloned and characterized as a subgroup of the family of receptor tyrosine kinases. Four FGF receptor genes were identified, all of which encode membrane-bound glycoproteins containing three immunoglobulin (Ig) -like domains at the extracellular region, where only two of these domains are involved in ligand binding. Three unique features characterize the FGF receptors: 1) overlapping recognition and redundant specificity, where one receptor may bind with a similar affinity several of the seven known FGFs and one FGF may bind similarly to several distinct receptors. 2) The binding of FGFs to their receptors is dependent on the interaction of FGF with cell surface heparan sulfate proteoglycans. 3) A multitude of isoforms of cell-bound or secreted receptors are produced by the same gene. The gene structure of these receptors revealed two major mechanisms that are responsible for the formation of the diverse forms: alternative mRNA splicing, resulting in deletions or alternate exons usage, and internal polyadenylation, resulting in truncated products. These are reminiscent of mechanisms that also operate in the immunoglobulin family to generate diversity and to produce either secreted or cell-bound molecules. Tissue-specific alternative splicing in FGF receptors allows for the generation of two distinct receptors from a single gene because alternative exons determine the sequence of the COOH-terminal half of the third Ig-like domain involved in ligand binding. This represents a novel genetic mechanism to generate receptor diversity and specificity and to increase receptor repertoire.

Animals↗

[Expression and its significance of b-FGF in human benign prostatic hyperplasia and prostatic carcinoma tissues].

AIM: To investigate the clinical significance of basic fibroblast growth factor (b-FGF) in human benign prostatic hyperplasia (BPH) and prostatic carcinoma (Pca). METHODS: b-FGF expressions were examined by RNA dot blot hybridization and immunohistochemical staining in prostate tissues from 40 normal cases (NP), 38 BPH and 36 Pca. RESULTS: The expressions of b-FGF in BPH and Pca tissues were significantly higher than those in normal prostate tissues (P < 0.01). There was no significant correlation between the increased expression of b-FGF and the graduation of BPH, pathologic grading as well as clinical stages of Pca. CONCLUSION: b-FGF may be secreted from BPH and Pca tissues themselves, which is closely involved in the genesis and development of BPH and Pca.

Aged↗

[The correlation between the expansion volume and the contents of b-FGF and EGF in the expanded skin].

OBJECTIVE: To study the correlation between the expansion with different volume and the contents of the b-FGF and EGF in the expanded skin. METHODS: The piglets were used in the experiment,which were divided into 7 groups including the sham, the blank control,the experimental groups with inflation of 1/2 volume, 3/4 volume, full volume, 150% volume and 200% volume. When expansion was complete, b-FGF was measured using enzyme coagulate method. EGF was measured by radioimmunoassay. The data were analyzed statistically. RESULTS: The contents of b-FGF and EGF in the expanded skin was significantly higher than normal skin (P < 0.05). The difference in contents of b-FGF and EGF between the over-expanded skin and normal skin was more significant (P < 0.01). CONCLUSION: Expansion can lead to the increase of b-FGF and EGF contents in the expanded skin.The biological effects may be relative to epidermal hyperplasia and angiogenesis of the expanded skin.

Animals↗

Immunohistochemical expression of FGF-2, PDGF-A, VEGF and TGF beta RII in the pancreas in the course of ischemia/reperfusion-induced acute pancreatitis.

UNLABELLED: Acute pancreatitis leads to pancreatic damage followed by subsequent regeneration. The aim of our study was to evaluate the presence of growth factors in the course of spontaneous pancreatic regeneration after ischemia/reperfusion (I/R)-induced pancreatitis. METHODS: In rats, I/R was evoked by clamping of splenic artery for 30 min followed by reperfusion. Rats were sacrificed 1, 5, 12 h or 1, 2, 3, 5, 7, 9 or 21 days after removal of vascular clips. Pancreatic blood flow (PBF), plasma lipase, interleukin-1beta (IL-1beta), interleukin-10, pancreatic cells proliferation and morphological signs of pancreatitis were determined. Pancreatic presence of fibroblast growth factor-2 (FGF-2), vascular endothelial growth factor (VEGF), platelet-derived growth factor-A (PDGF-A) and transforming growth factor-beta type II receptor (TGFbeta RII) was detected by immunohistochemisty. RESULTS: Exposure to I/R led to the development of acute necrotizing pancreatitis followed by regeneration. Morphological features showed maximal pancreatic damage between the 1(st) and 2(nd) day of reperfusion. It was correlated with a maximal increase in plasma lipase, and pro-inflammatory IL-1beta concentration, as well as, a reduction in PBF and pancreatic DNA synthesis. I/R increased FGF-2 content in pancreatic acinar cells between the 12(th) and 24(th) h, and between 5(th) and 9(th) day of reperfusion. At the 2(nd) day the presence of FGF-2 in pancreatic acinar cells was reduced. After I/R PDGF-A appeared in pancreatic vessels from the 12(th) h to 5 (th) day of reperfusion. PDGF-A was not observed in pancreatic acinar cells in the control or in I/R group. In pancreatic ducts, the presence of PDGF-A was reduced between the 1(st) and 3(rd), and between 7(th) and 9(th) day of reperfusion. In acinar cells, VEGF content was increased after I/R at the time between the 1(st) and 24(th) h, and between 3(rd) and 7(th) day of reperfusion. At the 2(nd) day of reperfusion, VEGF was not detected in the pancreatic acinar cells. Moreover, VEGF was found in the inflammatory infiltration, in the tubular complexes between the 2(nd) and 5(th) day, and in granulation tissue at the 9(th) day of reperfusion. In pancreatic acinar cells, I/R caused an increase in TGFbeta RII presence between the 5(th) and 24(th) h, and between 7(th) and 9(th) day of reperfusion. Between the 2(nd) and 5(th) day of reperfusion the acinar presence of TGFbeta RII was reduced. In the pancreatic ducts, the presence of TGFbeta RII was increased after I/R from the 1(st) h to 9(th) day of observation. Four weeks after induction of acute pancreatitis, the pancreatic regeneration was completed and the presence of growth factors tested returned to control value. CONCLUSIONS: The presence of FGF, VEGF, PDGF-A and TGFbeta RII is modified in the course of I/R-induced acute pancreatitis. Maximal content of FGF, VEGF and TGFbeta RII has been observed in early stage of pancreatic regeneration suggesting the involvement these factors in pancreatic recovery.

Animals↗

Transfection of mesenchymal stem cells with the FGF-2 gene improves their survival under hypoxic conditions.

Bone marrow mesenchymal stem cells (MSCs) have shown potential for cardiac repair following myocardial injury, but this approach is limited by their poor viability after transplantation. To reduce cell loss after transplantation, we introduced the fibroblast growth factor-2 (FGF-2) gene ex vivo before transplantation. The isolated MSCs produced colonies with a fibroblast-like morphology in 2 weeks; over 95% expressed CD71, and 28% expressed the cardiomyocyte-specific transcription factor, Nkx2.5, as well as a-skeletal actin, Nkx2.5, and GATA4. In hypoxic culture, the FGF-2-transfected MSCs (FGF-2-MSCs) secreted increased levels of FGF-2 and displayed a threefold increase in viability, as well as increased expression of the anti-apoptotic gene, Bcl2, and reduced DNA laddering. They had functional adrenergic receptors, like cardiomyocytes, and exposure to norepinephrine led to phosphorylation of ERK1/2. Viable cells persisted 4 weeks after implantation of 5.0 yen 105 FGF-2-MSCs into infarcted myocardia. Expression of cardiac troponin T (CTn T) and a voltage-gated Ca2+ channel (CaV2.1) increased, and new blood vessels formed. These data suggest that genetic modification of MSCs before transplantation could be useful for treating myocardial infarction and end-stage cardiac failure.

Animals↗

[Fibroblast growth factor (FGF)-23 in patients with hypoparathyroidism].

Hypoparathyroidism is a well-described cause of hyperphosphatemia. We aimed to clarify the physiological role of FGF-23 in serum phosphate homeostasis in hypoparathyroidism after thyroidectomy. Increased serum FGF-23 levels were found in patients with hyperphosphatemia and hypocalcemia, caused by hypoparathyroidism after thyroidectomy. After the recovery of parathyroid function, the serum level of calcium, phosphate, and FGF-23 was normalized. Serum FGF-23 levels were significantly higher in patients with permanent hypoparathyroidism than in healthy controls. These results indicate that FGF-23 may play an important role in serum phosphate homeostasis by its up-regulation in the hyperphosphatemic condition.

Female↗

Alternative splicing generates at least five different isoforms of the human basic-FGF receptor.

Fibroblast growth factors (FGFs) are polypeptide mitogens that induce the proliferation of a wide variety of cell types. Of the seven family members, the best characterized are basic and acidic FGF. In addition to their mitogenic effects, they participate in angiogenesis, differentiation and maintenance of survival of neurons, cell migration and embryonal development. Of all family members, keratinocyte growth factor (KGF) is unique in that it is a specific mitogen for epithelial cells and does not interact with the FGF receptor of fibroblasts. To study the interactions between KGF and its receptor, we isolated KGF and FGF receptors from keratinocytes and fibroblasts, respectively. In the course of this study, we isolated five different variants of the FGF receptor from human fibroblasts and showed that all were derived from a single genetic locus. Four of these variants encode transmembrane receptors and can be divided into two subgroups that differ from one another with respect to the number (two or three) of immunoglobulin (Ig)-like domains. Within each subgroup, one receptor differed from the other by the presence of a two-codon insertion. Thus, all the variations among the four isoforms are localized to their ligand binding domains. The fifth isoform encodes a molecule truncated just 3' to the first Ig-like domain and thus could be secreted from the cell. The transcripts encoding the long and short isoforms were found to be expressed in many cell types, but their relative levels of expression varied greatly depending on the cell type. These findings indicate that alternative splicing generates diverse FGF receptor isoforms in human cells.

Amino Acid Sequence↗

The role of basic-fibroblast growth factor (b-FGF) in cyclosporine-induced nephrotoxicity.

BACKGROUND: The effect of the b-fibroblast growth factor (b-FGF) on cyclosporine A (CsA)-induced nephrotoxicity in the rat kidney was investigated. MATERIALS AND METHODS: The rats were divided into six groups: A (control), B (b-FGF-treated), C, D: (CsA-treated and sacrificed on days 14 or 21), E, F (Cs A- and b-FGF- treated and sacrificed on days 14 or 21). The antibody mouse anti-rat CD31 was used to evaluate the kidney vessels present in histological preparations. RESULTS: The kidney vessels in group B were increased in comparison with the control group (p<0.05). Reduction of kidney vessels in groups C and D (p<0.05) in comparison with the controls was observed, while in groups E and F they were increased when compared to group C (p<0.05) and D (p<0.05), respectively. CONCLUSION: The angiogenic role of b-FGF was confirmed in normal rats and a possible "protective" role of b-FGF was shown in rat kidney with CsA-induced nephrotoxicity.

Animals↗

FGF signaling network in the gastrointestinal tract (review).

Fibroblast growth factor (FGF) signals are transduced through FGF receptors (FGFRs) and FRS2/FRS3- SHP2 (PTPN11)-GRB2 docking protein complex to SOS-RAS-RAF-MAPKK-MAPK signaling cascade and GAB1/GAB2-PI3K-PDK-AKT/aPKC signaling cascade. The RAS approximately MAPK signaling cascade is implicated in cell growth and differentiation, the PI3K approximately AKT signaling cascade in cell survival and cell fate determination, and the PI3K approximately aPKC signaling cascade in cell polarity control. FGF18, FGF20 and SPRY4 are potent targets of the canonical WNT signaling pathway in the gastrointestinal tract. SPRY4 is the FGF signaling inhibitor functioning as negative feedback apparatus for the WNT/FGF-dependent epithelial proliferation. Recombinant FGF7 and FGF20 proteins are applicable for treatment of chemotherapy/radiation-induced mucosal injury, while recombinant FGF2 protein and FGF4 expression vector are applicable for therapeutic angiogenesis. Helicobacter pylori, a causative pathogen for peptic ulcer diseases, chronic atrophic gastritis and gastric cancer, injects bacterial proteins into gastric epithelial cells by using Type IV secretion system, which leads to FGF signaling activation through FGF2 upregulation as well as CagA-dependent SHP2 activation. FGFR2 gene is preferentially amplified and overexpressed in diffuse-type gastric cancer. PD173074 is a small-molecule inhibitor for FGFR, while RO4396686 and SU6668 are small-molecule inhibitors for FGFR and other tyrosine kinases. Cocktail therapy using multiple protein kinase inhibitors could enhance the therapeutic effects for gastrointestinal cancer through the reduction of recurrence associated with somatic mutations of drug-target genes. Single nucleotide polymorphism (SNP) and copy number polymorphism (CNP) of genes encoding FGF signaling molecules will be identified as novel risk factors of gastrointestinal cancer. Personalized prevention and personalized medicine based on the combination of genetic screening and novel therapeutic agents could dramatically improve the prognosis of cancer patients.

Amino Acid Sequence↗