Cloning and expression of cDNA encoding human basic fibroblast growth factor

From shape-shifting embryonic cells to oncology: The fascinating history of epithelial mesenchymal transition

Epithelial-to-mesenchymal transition or transformation (EMT) is a cell shape-changing process that is utilized repeatedly throughout embryogenesis and is critical to the attainment of a precise body plan. In the adult, EMT is observed under both normal and pathological conditions, such as during normal wounding healing, during development of certain fibrotic states and vascular anomalies, as well as in some cancers when malignant cells progress to become more aggressive, invasive, and metastatic. Epithelia derived from any of the three embryonic germ layers can undergo EMT, including those derived from mesoderm, such as endothelial cells (sometimes termed Endo-MT) and those derived from endoderm such as fetal liver stroma. At the cellular level, EMT is defined as the transformation of epithelial cells towards a mesenchymal phenotype and is marked by attenuation of expression of epithelial markers and de novo expression of mesenchymal markers. This process is induced by extracellular factors and can be reversible, resulting in mesenchymal-to-epithelial transformation (MET). It is now clear that a cell can simultaneously express properties of both epithelia and mesenchyme, and that such transitional cell-types drive tumor cell heterogeneity, an important aspect of cancer progression, development of a stem-like cell state, and drug resistance. Here we review some of the earliest studies demonstrating the existence of EMT during embryogenesis and discuss the discovery of the extracellular factors and intracellular signaling pathways that contribute to this process, with components of the TGFβ signaling superfamily playing a prominent role. We mention early controversies surrounding in vivo EMT during embryonic development and in adult diseased states, and the maturation of the field to a stage wherein targeting EMT to control disease states is an aspirational goal.

Fibroblast growth factor 2

Fibroblast Growth Factor 2 (FGF2), also known as basic fibroblast growth factor, is a potent stimulator of growth and differentiation in multiple tissues. Its discovery traces back over 50 years ago when it was first isolated from bovine pituitary extracts due to its ability to stimulate fibroblast proliferation. Subsequent studies investigating the genomic structure of FGF2 identified multiple protein isoforms, categorized as the low molecular weight and high molecular weight FGF2. These isoforms arise from alternative translation initiation events and exhibit unique molecular and cellular functions. In this concise review, we aim to provide an overview of what is currently known about the structure, expression, and functions of the FGF2 isoforms within the contexts of development, homeostasis, and disease.

Matrin-3 is essential for fibroblast growth factor 2-dependent maintenance of neural stem cells

To investigate the mechanisms underlying the maintenance of neural stem cells, we performed two-dimensional fluorescence-difference gel electrophoresis (2D-DIGE) targeting the nuclear phosphorylated proteins. Nuclear phosphorylated protein Matrin-3 was identified in neural stem cells (NSCs) after stimulation using fibroblast growth factor 2 (FGF2). Matrin-3 was expressed in the mouse embryonic subventricular and ventricular zones. Small interfering RNA (siRNA)-mediated knockdown of Matrin-3 caused neuronal differentiation of NSCs in vitro, and altered the cerebral layer structure of foetal brain in vivo. Transfection of Matrin-3 plasmids in which the serine 208 residue was point-mutated to alanine (Ser208Ala mutant Matrin3) and inhibition of Ataxia telangiectasia mutated kinase (ATM kinase), which phosphorylates Matrin-3 Ser208 residue, caused neuronal differentiation and decreased the proliferation of neurosphere-forming stem cells. Thus, our proteomic approach revealed that Matrin-3 phosphorylation was essential for FGF2-dependent maintenance of NSCs in vitro and in vivo.

Novel Bioluminescent Binding Assays for Ligand-Receptor Interaction Studies of the Fibroblast Growth Factor Family

We recently developed novel bioluminescent binding assays for several protein/peptide hormones to study their interactions with receptors using the so far brightest NanoLuc reporter. To validate the novel bioluminescent binding assay using a variety of protein/peptide hormones, in the present work we applied it to the fibroblast growth factor (FGF) family using the prototype member FGF2 as an example. A fully active recombinant FGF2 retaining a unique exposed cysteine (Cys) residue was chemically conjugated with an engineered NanoLuc carrying a unique exposed Cys residue at the C-terminus via formation of an intermolecular disulfide linkage. The NanoLuc-conjugated FGF2 (FGF2-Luc) retained high binding affinity to the overexpressed FGFR1 and the endogenous FGF receptor with the calculated dissociation constants of 161 ± 21 pM (n = 3) and 25 ± 4 pM (n = 3), respectively. In competition binding assays using FGF2-Luc as a tracer, receptor-binding potencies of wild-type or mutant FGF2s were accurately quantified. Thus, FGF2-Luc represents a novel non-radioactive tracer for the quantitative measurement of ligand–receptor interactions in the FGF family. These data suggest that the novel bioluminescent binding assay can be applied to a variety of protein/peptide hormones for ligand–receptor interaction studies.

Correlation between plasma and synovial fluid basic fibroblast growth factor with radiographic severity in primary knee osteoarthritis

PURPOSE

The aim of this study was to investigate plasma and synovial fluid basic fibroblast growth factor (bFGF) levels in patients with primary knee osteoarthritis (OA) and to evaluate the correlation between bFGF levels and disease severity.

METHODS

Thirty-five patients with knee OA and 15 healthy individuals were recruited into this study. Knee OA grading was performed according to the Kellgren-Lawrence classification. bFGF concentrations in both plasma and synovial fluid were determined using enzyme-linked immunosorbent assay.

RESULTS

Plasma and synovial fluid bFGF levels in knee OA patients were significantly higher than in controls (P < 0.001). Moreover, plasma and synovial fluid bFGF concentrations were positively correlated with radiographic severity (r = 0.535, P < 0.001 and r = 0.570, P < 0.001, respectively). Further analysis revealed that there was a positive correlation between plasma and synovial fluid bFGF levels (r = 0.674, P < 0.001).

CONCLUSIONS

Plasma and synovial fluid bFGF levels were significantly increased in OA patients, and these elevated levels were positively correlated with radiographic severity. These findings indicate that bFGF levels may be a monitor of disease severity and could play an essential part in the pathophysiology of degenerative process in OA.

Role of fibroblast growth factor-2 in the expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in human intestinal myofibroblasts

BACKGROUND AND AIMS

The coordinated expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) plays a crucial role in tissue remodeling. We investigated the effects of fibroblast growth factor (FGF)-2 on the secretion of MMPs and TIMPs in human intestinal subepithelial myofibroblasts (SEMFs).

METHODS

The secretion of MMP-s and TIMPs was determined by ELISA or Western blotting. The mRNA expression of MMPs and TIMPs was assessed by Northern blotting. The activating protein (AP)-1-DNA binding activity was evaluated by electrophoretic gel mobility shift assays (EMSA).

RESULTS

Unstimulated intestinal SEMFs constitutively secreted MMP-2 and TIMP-2. FGF-2 stimulated MMP-1, MMP-3 and TIMP-1 secretion, but did not affect MMP-2 or TIMP-2 secretion. FGF-2 induced AP-1-DNA binding activity, and the c-Jun/AP-1 inhibitor curcumin attenuated the FGF-2-induced MMP-1, -3 and TIMP-1 mRNA expression. Mitogen-activated protein (MAP) kinase inhibitors (U0126 and PD098059) also blocked the MMP-1, -3 and TIMP-1 secretion. Furthermore, FGF-2 dose-dependently induced FGF-2 mRNA expression in these cells.

CONCLUSIONS

FGF-2 may be one of important regulatory factors for extracellular matrix turnover via a modulation of MMP and TIMP secretion from SEMFs.

Efficient proliferation and adipose differentiation of human adipose tissue-derived vascular stromal cells transfected with basic fibroblast growth factor gene

Human vascular stromal (VS) cells obtained from mature adipose tissue were transfected with an adenovirus vector carrying the basic fibroblast growth factor (bFGF) gene. bFGF protein was observed in VS cell nuclei 24 h after transfection and in the cytoplasm and extracellular space 72 h after transfection. Naive VS cells were almost static in vitro and proliferated in a dose-dependent manner on stimulation with recombinant bFGF (rbFGF). However, bFGF-transfected VS cells proliferated spontaneously to the same extent as naive VS cells when stimulated with rbFGF at 100 ng/ml. The former cells started to proliferate on day 3 after transfection and the proliferation pattern was similar to that of the latter cells, although only a slight amount of bFGF protein was detected in the culture medium when the bFGF-transfected cells started to proliferate. The proliferation of bFGF-transfected VS cells was completely inhibited by bFGF neutralizing antibody, which also completely inhibited the proliferation of naive VS cells stimulated with rbFGF. Under conditions favoring differentiation to adipocytes, bFGF-transfected VS cells stopped proliferating and started to accumulate lipid in the cytoplasm. bFGF-transfected VS cells, which spontaneously and efficiently proliferate while preserving their ability to differentiate into adipocytes, may be an adequate cell source for human adipose tissue regeneration.

Role of chemokines in angiogenesis: CXCL12/SDF-1 and CXCR4 interaction, a key regulator of endothelial cell responses

Chemokines are small proteins that act as cell attractants via the activation of G protein-coupled receptors. Chemokines play an important role in several pathophysiological processes such as inflammation and immunity. Many proinflammatory chemokines also support the development of vascular blood supply at the site of inflammation. Similarly, tumor-generated chemokines can contribute to tumor growth by promoting angiogenesis. Recently, significant advances have been made in understanding the contribution of chemokines to the angiogenesis process. This review will discuss first the evidence supporting the direct contribution of different chemokine subfamily members, including CC, CXC, and CX3C chemokines, as positive or negative regulators of the angiogenesis process based on the expression of their cognate receptors on endothelial cells. Additionally, the relationship between classic angiogenic factors and chemokine receptor expression on endothelial cells, and the implications of chemokine production by cancer cells will be analyzed with particular emphasis on the CXCL12/stromal-cell derived factor-1 interaction with CXCR4.

Microglia-Müller glia cell interactions control neurotrophic factor production during light-induced retinal degeneration

Activation of microglia commonly occurs in response to a wide variety of pathological stimuli including trauma, axotomy, ischemia, and degeneration in the CNS. In the retina, prolonged or high-intensity exposure to visible light leads to photoreceptor cell apoptosis. In such a light-reared retina, we found that activated microglia invade the degenerating photoreceptor layer and alter expression of neurotrophic factors such as nerve growth factor (NGF), ciliary neurotrophic factor (CNTF), and glial cell line-derived neurotrophic factor (GDNF). Because these neurotrophic factors modulate secondary trophic factor expression in Müller glial cells, microglia-Müller glia cell interaction may contribute to protection of photoreceptors or increase photoreceptor apoptosis. In the present study, we demonstrate the possibility that such functional glia-glia interactions constitute the key mechanism by which microglia-derived NGF, brain-derived neurotrophic factor (BDNF), and CNTF indirectly influence photoreceptor survival, although the receptors for these neurotrophic factors are absent from photoreceptors, by modulating basic fibroblast growth factor (bFGF) and GDNF production and release from Müller glia. These observations suggest that microglia regulate the microglia-Müller glia-photoreceptor network that serves as a trophic factor-controlling system during retinal degeneration.

Identification of FGF receptor-binding peptides for cancer gene therapy

Linear FGF receptor-binding heptapeptides were identified by phage display using sequential rounds of biopanning against cells with displacement of phage by FGF2. The consensus motif MXXP was iterated after four to five rounds and the peptide MQLPLAT was studied in depth. Phage bearing MQLPLAT showed high levels of binding to FGF receptor positive cells, with over 90% of phage bound being eluted competitively by adding free FGF2. MQLPLAT phage showed only limited binding to Cos7 cells deficient in receptors for FGF. MQLPLAT phage bound to SKOV3 cells with a K(d) of 2.51 x 10(-10) M. Although binding could be blocked by preincubation with free FGF2, heparin could not displace the phage. Use of MQLPLAT to target polyelectrolyte gene delivery vectors in vitro in the presence of serum achieved up to 40-fold greater transgene transduction than nontargeted vectors. MQLPLAT phage were administered into gastric carcinomas via the tumor-feeding artery immediately following resection from patients. The phage showed up to 9-fold more accumulation in the tumor than in adjacent regions of normal tissue, whereas control phage showed less than 2-fold. These peptides should provide useful ligands for specific delivery of gene therapy vectors to clinically relevant targets.

Gene therapy in plastic surgery

Recent developments in gene therapy have shown promise in the treatment of soft-tissue repair, bone formation, nerve regeneration, and cranial suture development. This special topic article reviews commonly used methods of gene therapy and discusses their various advantages and disadvantages. In addition, an overview of new developments in gene therapy as they relate to plastic surgery is provided.

Regulation of renal proximal tubular epithelial cell fibroblast growth factor-2 generation by heparin

Progression of renal disease is closely correlated to the degree of renal interstitial fibrosis, and evidence is increasing that epithelial cells of the renal proximal tubule (PTCs) may contribute to its pathogenesis. Such cytokines as basic fibroblast growth factor (FGF-2) have been implicated in progressive renal injury, and we previously showed that PTCs are a source of this cytokine. FGF-2 is characterized by its high affinity for heparin, and numerous studies have suggested that heparin may modify the progression of renal disease. The current study examined how heparin influenced FGF-2 generation and bioactivity in the human renal epithelial PTC line, HK-2. Incubation of HK-2 cells with heparin led to a dose- and time-dependent increase in FGF-2 concentration in the culture supernatant that was not accompanied by alterations in FGF-2 messenger RNA expression, assessed by reverse-transcriptase polymerase chain reaction and Northern analysis. The heparin-induced increase in FGF-2 concentration was accompanied by a decrease in the amount of FGF-2 bound to the extracellular matrix, although this accounted for only a small proportion of the total FGF-2 generated. Induction of FGF-2 by 2-O-desulfated heparin, together with a reduction in total cell-associated FGF-2 and anti-FGF-2 antibody binding to fixed permeabilized cells after the addition of heparin, suggested that the FGF-2 released was mainly derived from a preformed intracellular source. That FGF-2 was predominantly derived from an intracellular pool was also confirmed by pulse chase experiments. The addition of heparin resulted in the generation of bioinactive FGF-2, judged by in vitro fibroblast proliferation. Conversely, heparitinase treatment of supernatant samples from heparin-treated cells and the addition of 2-O-desulfated heparin resulted in the generation of active FGF-2, suggesting that the generation of bioinactive FGF-2 was related to binding of FGF-2 by extracellular heparin after its release from cells. These data show that heparin depletes both the cell and surrounding matrix of FGF-2 and suggest that FGF-2 released from cells was mainly derived from a preformed intracellular source. Furthermore, FGF-2 released from epithelial PTCs after the application of heparin was bioinactive. This likely resulted from released FGF-2 binding to an excess of extracellular heparin. Results presented here therefore suggest a mechanism by which heparin, through its effect on depletion of matrix and cells of FGF-2 and its generation in an inactive form, may influence progressive renal interstitial fibrosis.

Muscle angiogenic growth factor gene responses to exercise in chronic renal failure

Patients with chronic renal failure (CRF) have impaired exercise capacity even after erythropoietin treatment. We recently showed that although this is explained in part by reduced convective O(2) delivery to muscles, there is also an impairment of O(2) transport from muscle capillaries to the mitochondria. Given the importance of the capillary surface area for capillary mitochondrial O(2) transport and reports of reduced capillarity in CRF, we hypothesized that the angiogenic gene response to exercise is impaired in such patients. Six patients with CRF and six control subjects matched for age, size, and sedentary lifestyle exercised on a single occasion for 1 h at similar work intensities averaging 50% of maximal capacity. Exercise was confined to the knee extensors of a single leg by means of a specially designed leg-kick ergometer. A percutaneous biopsy of the quadriceps was taken within 30 min of cessation of exercise and compared with a similar biopsy done at different times without any prior exercise for 24 h. Conventional Northern blots were prepared and probed for vascular endothelial growth factor (VEGF; the major putative angiogenic growth factor for muscle), basic fibroblast growth factor (bFGF), and transforming growth factor (TGF)-beta(1). Data during both rest and exercise were successfully obtained in four subjects of each group. We also assessed muscle capillarity and mitochondrial oxidative capacity to relate to these changes. Mitochondrial oxidative capacity was normal, whereas capillary number per fiber was 12% lower than in normal subjects. VEGF mRNA abundance was increased after exercise by about one order of magnitude, with no reduction in response in CRF. For bFGF and TGF-beta(1), exercise elicited no response in either group. Reduced muscle capillarity in CRF does not, therefore, stem from reduced transcription of VEGF. To the extent that VEGF is important to exercise-induced angiogenesis in muscle, we suspect a posttranscriptional aberration in this response occurs in CRF to explain reduced capillarity.

Adenovirus-mediated ex vivo gene transfer of basic fibroblast growth factor promotes collateral development in a rabbit model of hind limb ischemia

Adenovirus-mediated ex vivo gene transfer of basic fibroblast growth factor (bFGF), a new strategy for the treatment of chronic vascular occlusive disease, was examined in a rabbit model of hind limb ischemia. The left femoral artery was completely excised to induce an ischemic state in the hind limb of male rabbits. Simultaneously, a skin section was resected from the wound, and host fibroblasts were cultured. The cultured fibroblasts were infected with adenovirus vector containing modified human bFGF cDNA with the secretory signal sequence (AxCAMAssbFGF) or LacZ cDNA (AxCALacZ). At 21 days after femoral artery excision, the gene-transduced fibroblasts were administered through the left internal iliac artery. The fibroblasts significantly accumulated in the ischemic hind limb, and the AxCAMAssbFGF-treated cells secreted bFGF for less than 14 days without elevation of systemic bFGF level. At 28 days after cell administration, calf blood pressure ratio, angiographic score, capillary density of muscle tissue and blood flow of the left internal iliac artery were determined, and animals with AxCAMAssbFGF-treated cells showed significantly greater development of collateral vessels, as compared with those with AxCALacZ-treated cells. These findings suggest that adenovirus-mediated ex vivo gene transfer of bFGF was effective for improvement of chronic limb ischemia.

A novel alternatively spliced fibroblast growth factor receptor 3 isoform lacking the acid box domain is expressed during chondrogenic differentiation of ATDC5 cells

To determine the role of fibroblast growth factor (FGF).FGF receptor (FGFR) signaling in chondrogenesis, we analyzed the gene expression of alternatively spliced FGFRs during chondrogenic differentiation of ATDC5 cells in vitro. Two isoforms of FGFR3 were expressed in these cells. One was the complete form of FGFR3 (FGFR3) already reported, and the other was a novel one that lacks the acid box domain (FGFR3DeltaAB). The gene of FGFR3DeltaAB was expressed in undifferentiated ATDC5 cells. In contrast, the transcripts of FGFR3 were not detectable in undifferentiated cells but increased during cellular condensation, which is an obligatory step for chondrogenic differentiation. FGFR1 and FGFR2 expression was higher than that of FGFR3 in undifferentiated cells. The gene expression of cell cycle inhibitor p21 was induced during cell condensation and correlated best with the expression of FGFR3 among the FGFR isoforms expressed. The differential expression of FGFR3 isoforms during chondrogenesis suggests that these isoforms may play different roles in the regulation of growth and differentiation in chondrocytes. To define the mitogenic response of FGFR3DeltaAB and FGFR3 to FGFs, their cDNAs were stably transfected into mouse BaF3 pro-B cells. FGFR3 preferentially mediates the mitogenic response to FGF1 and poor response to FGF2. In contrast, FGFR3DeltaAB mediated a higher mitogenic response to FGF2 as well as to FGF1. In addition, FGFR3DeltaAB responds to FGF1 at lower concentrations of heparin than FGFR3 does. These results suggest that the acid box plays an important role in the regulation of FGFR3 to mediate biological activities in response to FGFs.

Expression of fibroblast growth factors 1 and 2 in a human retinal pigment epithelium cell line (K1034)

The primary source of fibroblast growth factors (FGFs) is the retinal pigment epithelium (RPE). Investigations on FGF secretion in RPE primary cultures are hampered by the rapid run-down of cell vitality after a few passages. Therefore, long-term experiments require an alternative to primary cultures. We detected FGF-1 and FGF-2 in the established human K1034 cell line by immunohistochemistry. In addition, mRNA for both FGFs was found by RT-PCR. By immunohistochemistry, the signal was more pronounced with FGF-2 than with FGF-1. K1034 is capable of expressing both FGF-1 and FGF-2. With respect to these features, this cell line can be used as an alternative to primary cultured human RPE cells.

Exercise adaptation attenuates VEGF gene expression in human skeletal muscle

Angiogenesis is a component of the multifactoral adaptation to exercise training, and vascular endothelial growth factor (VEGF) is involved in extracellular matrix changes and endothelial cell proliferation. However, there is limited evidence supporting the role of VEGF in the exercise training response. Thus we studied mRNA levels of VEGF, using quantitative Northern analysis, in untrained and trained human skeletal muscle at rest and after a single bout of exercise. Single leg knee-extension provided the acute exercise stimulus and the training modality. Four biopsies were collected from the vastus lateralis muscle at rest in the untrained and trained conditions before and after exercise. Training resulted in a 35% increase in muscle oxygen consumption and an 18% increase in number of capillaries per muscle fiber. At rest, VEGF/18S mRNA levels were similar before (0.38 +/- 0.04) and after (1.2 +/- 0.4) training. When muscle was untrained, acute exercise greatly elevated VEGF/18S mRNA levels (16.9 +/- 6.7). The VEGF/18S mRNA response to acute exercise in the trained state was markedly attenuated (5.4 +/- 1.3). These data support the concept that VEGF is involved in exercise-induced skeletal muscle angiogenesis and appears to be subject to a negative feedback mechanism as exercise adaptations occur.

Adenoviral gene transfer of basic fibroblast growth factor promotes angiogenesis in rat brain

Cerebral ischemic disease often causes morbidity and mortality, while the induction of new blood vessels is expected to provide a therapeutic effect in this occlusive cerebrovascular disease. In this study, we utilized two replication-deficient adenoviral vectors containing cDNA from basic fibroblast growth factor (bFGF), a well-known angiogenic factor, and examined whether biological angiogenic activity of adenovirally gene-transferred bFGF could be observed in the rat brain. One vector contained native cDNA from bFGF without the secretory signal sequence and the other contained the same cDNA fused with an interleukin-2 secretory signal sequence. After ventricular administration of these viral vectors, gene-transferred cells demonstrated a high immunoreactivity against the anti-bFGF antibody and a remarkably high concentration of bFGF was detected in the cerebrospinal fluid. A semiquantitative analysis of angiogenic activity revealed that bFGF gene transfer induced angiogenesis in normal rat brains, with a more pronounced angiogenic effect seen with the vector of a secreted form than with the vector without a secretory signal sequence. These results suggest that bFGF gene transfer using these adenoviral vectors might be useful for the treatment of ischemic cerebrovascular disease.

Effect of captopril on skeletal muscle angiogenic growth factor responses to exercise

Acute exercise increases vascular endothelial growth factor (VEGF), transforming growth factor-beta(1) (TGF-beta(1)), and basic fibroblast growth factor (bFGF) mRNA levels in skeletal muscle, with the greatest increase in VEGF mRNA. VEGF functions via binding to the VEGF receptors Flk-1 and Flt-1. Captopril, an angiotensin-converting enzyme inhibitor, has been suggested to reduce the microvasculature in resting and exercising skeletal muscle. However, the molecular mechanisms responsible for this reduction have not been investigated. We hypothesized that this might occur via reduced VEGF, TGF-beta(1), bFGF, Flk-1, and Flt-1 gene expression at rest and after exercise. To investigate this, 10-wk-old female Wistar rats were placed into four groups (n = 6 each): 1) saline + rest; 2) saline + exercise; 3) 100 mg/kg ip captopril + rest; and 4) 100 mg/kg ip captopril + exercise. Exercise consisted of 1 h of running at 20 m/min on a 10 degrees incline. VEGF, TGF-beta(1), bFGF, Flk-1, and Flt-1 mRNA were analyzed from the left gastrocnemius by quantitative Northern blot. Exercise increased VEGF mRNA 4.8-fold, TGF-beta(1) mRNA 1.6-fold, and Flt-1 mRNA 1.7-fold but did not alter bFGF or Flk-1 mRNA measured 1 h after exercise. Captopril did not affect the rest or exercise levels of VEGF, TGF-beta(1), bFGF, and Flt-1 mRNA. Captopril did reduce Flk-1 mRNA 30-40%, independently of exercise. This is partially consistent with the suggestion that captopril may inhibit capillary growth.

Nitric oxide synthase inhibition attenuates the skeletal muscle VEGF mRNA response to exercise

Vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and transforming growth factor-beta(1) (TGF-beta(1)) mRNA increase in rat skeletal muscle in response to a single acute exercise bout. Nitric oxide (NO) is released locally by muscle vascular endothelium and muscle fibers during exercise, contributes to the blood flow response to exercise, and regulates mitochondrial respiration. We hypothesized that a reduction in NO production, via NO synthase inhibition, would demonstrate a link between NO and the VEGF, bFGF, and TGF-beta(1) gene responses to exercise. To investigate this hypothesis, 9-wk-old female Wistar rats were divided into eight treatment groups (n = 6 each): 1) saline + rest, 2) saline + exercise, 3) 30 mg/kg N(omega)-nitro-L-arginine methyl ester (L-NAME, a known NOS inhibitor) + rest, 4) 30 mg/kg L-NAME + exercise, 5) 300 mg/kg L-NAME + rest, 6) 300 mg/kg L-NAME + exercise, 7) 300 mg/kg N(omega)-nitro-D-arginine methyl ester (D-NAME, inactive enantiomer of L-NAME) + rest, and 8) 300 mg/kg D-NAME + exercise. Exercise consisted of 1 h of running at 20 m/min on a 10 degrees incline. VEGF, TGF-beta(1), and bFGF mRNA from left gastrocnemius were analyzed by quantitative Northern blot. Submaximal exercise for 1 h increased VEGF mRNA 4.2-fold and TGF-beta(1) mRNA 1.5-fold in untreated rats but did not increase bFGF mRNA. The exercise-induced increase in VEGF mRNA was attenuated approximately 50% by 30 and 300 mg/kg L-NAME; the TGF-beta(1) mRNA increase was unaffected by 300 mg/kg L-NAME. In addition, 300 mg/kg D-NAME had no effect on the exercise-induced increase in VEGF mRNA. Administration of 300 mg/kg L-NAME had no effect on bFGF mRNA. These findings suggest that NO is important in the regulation of the VEGF gene response to exercise through increases in VEGF transcription or by increases in the VEGF mRNA half-life.

Human VEGF gene expression in skeletal muscle: effect of acute normoxic and hypoxic exercise

Vascular endothelial growth factor (VEGF) is involved in extracellular matrix changes and endothelial cell proliferation, both of which are precursors to new capillary growth. Angiogenesis is a vital adaptation to exercise training, and the exercise-induced reduction in intracellular PO2 has been proposed as a stimulus for this process. Thus we studied muscle cell PO2 [myoglobin PO2 (MbPO2)] during exercise in normoxia and in hypoxia (12% O2) and studied the mRNA levels of VEGF in six untrained subjects after a single bout of exercise by quantitative Northern analysis. Single-leg knee extension provided the acute exercise stimulus: a maximal test followed by 30 min at 50% of the peak work rate achieved in this graded test. Because peak work rate was not affected by hypoxia, the absolute and relative work rates were identical in hypoxia and normoxia. Three pericutaneous needle biopsies were collected from the vastus lateralis muscle, one at rest and then the others at 1 h after exercise in normoxia or hypoxia. At rest (control), VEGF mRNA levels were very low (0.38 +/- 0.04 VEGF/18S). After exercise in normoxia or hypoxia, VEGF mRNA levels were much greater (16.9 +/- 6.7 or 7.1 +/- 1.8 VEGF/18S, respectively). In contrast, there was no measurable basic fibroblast growth factor mRNA response to exercise at this 1-h postexercise time point. Magnetic resonance spectroscopy of myoglobin confirmed a reduction in MbPO2 in hypoxia (3.8 +/- 0.3 mmHg) compared with normoxia (7.2 +/- 0.6 mmHg) but failed to reveal a relationship between MbPO2 during exercise and VEGF expression. This VEGF mRNA increase in response to acute exercise supports the concept that VEGF is involved in exercise-induced skeletal muscle angiogenesis but questions the importance of a reduced cellular PO2 as a stimulus for this response.

Quantitative analysis of growth-related factors in human pituitary adenomas. Lowered insulin-like growth factor-I and its receptor mRNA in growth hormone-producing adenomas

To elucidate the contribution of growth factors to the development, growth and behavior of human pituitary adenomas, the authors used competitive reverse transcription-polymerase chain reactions to quantify expression of mRNAs for growth factors extracted from pituitary adenomas. As previously diagnosed by endocrinologic evaluation, the pituitary adenomas in this study consisted of six prolactin-producing, six growth hormone (GH)-producing, four follicle-stimulating hormone producing and six nonfunctioning adenomas. The mRNAs examined included those for platelet-derived growth factor (PDGF) B-chain, transforming growth factor (TGF)-beta1, epidermal growth factor (EGF), basic fibroblast growth factor (bFGF) and insulin-like growth factor (IGF)-I and -II; proliferating cell nuclear antigen (PCNA) as an indicator of cell proliferation; and pituitary-specific transcription factor-1 (Pit-1) which is a nuclear transcription factor expressed in the anterior pituitary. All factors except the last were expressed in all adenomas, and expression of PDGF B-chain, TGF-beta1, EGF, bFGF and IGF-II did not differ between the four adenoma varieties. Pit-1 was expressed only in GH- and prolactin-producing adenomas. PCNA expression also showed no differences. However, IGF-I mRNA in GH-producing adenomas was significantly lower than in prolactin-producing and nonfunctioning adenomas despite high serum IGF-I levels (1121+/-253 ng/ml). The analysis on IGF-I receptor mRNA was significantly lowered in GH-producing adenoma compared with the other types of adenoma. These findings suggest that the attenuation of negative feedback through the pituitary GH-IGF-I axis may be involved in development of GH-producing adenoma.

TGF-beta1 stimulates the release of pre-formed bFGF from renal proximal tubular cells

BACKGROUND

It is now clear that the progression of renal disease is closely correlated to the degree of renal interstitial fibrosis. We have previously demonstrated that the renal proximal tubular epithelial cell may contribute to the fibrotic response by the generation of profibrotic cytokines. Transforming growth factor-beta1 (TGF-beta1) and basic fibroblast growth factor (bFGF) are two of a group of profibrotic cytokines that have been associated with the development of renal interstitial fibrosis. In this study, we have examined the influence of TGF-beta1 on the generation of bFGF by renal tubular epithelial cells.

METHODS

HK2 cells were grown to confluence and were serum deprived and stimulated with recombinant TGF-beta1 under serum-free conditions. Subsequently, supernatant, cell-associated, intracellular, and matrix-associated bFGF concentrations were determined by enzyme-linked immunosorbent assay (ELISA). bFGF mRNA expression was examined by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The exposure of confluent serum-deprived HK2 cells to TGF-beta1 led to a significant increase in bFGF concentration in the cell culture supernatant. Twenty-four hours following the addition of 10 ng/ml TGF-beta1, this represented a twofold increase in bFGF concentration (control, 102 pg/ml, N = 24, vs. 202 pg/ml, N = 19, P = 0.0001). Despite the increase in bFGF concentration in the supernatant, there was no change in the expression of bFGF mRNA following the addition of TGF-beta1. The addition of 10 ng/ml of TGF-beta1 led to a 30% decrease in the total cell-associated bFGF concentration (control, 8.51 ng/ml, N = 16, TGF-beta1, 6.01 ng/ml, N = 13, P = 0.0042). This decrease in intracellular bFGF was associated with a 15% reduction in anti-bFGF antibody binding to fixed permeabilized cells, following the addition of 10 ng/ml of recombinant TGF-beta1 (N = 9, P = 0.0007), suggesting that the mechanism of stimulation of bFGF by TGF-beta1 involved the release of preformed bFGF from within the cells. In addition, following the addition of TGF-beta1, there was a significant dose-dependent decrease in the amount of bFGF sequestered in the extracellular matrix. At a dose of 10 ng/ml TGF-beta, this represented a greater than sevenfold decrease (N = 9, P = 0.0007) in matrix-bound bFGF, although this represented less than 3% of the total bFGF released into the supernatant.

CONCLUSION

The data presented suggest that the main mechanism by which TGF-beta1 stimulates bFGF generation by proximal tubular epithelial cells is by stimulation of the secretion of preformed cytokine from within the cells.

Detection of 28S RNA with the FGF-2 cDNA at high stringency through related G/C-rich sequences

Fibroblast growth factor-2 (FGF-2) or basic FGF is a multifunctional protein that, through interaction with specific cell surface receptors, plays important roles in the growth and development of tissues and organs. Thus, considerable attention has focused on the control of FGF-2 gene expression, including assessments of RNA levels through blotting and the use of radiolabeled FGF-2 cDNA probes. Multiple transcripts of different sizes have been reported for FGF-2 by this approach, however, more recent evidence indicates that at least one of these RNAs of about 1.5 kb, is not an authentic FGF-2 transcript. A major band of 4.7 kb and a minor band of 6.1 kb were detected in total rat glial tumor cell RNA, using the 'intact' rat ovarian FGF-2 cDNA as a probe at high stringency. This cDNA contains both coding and 5'-untranslated sequences. Although the 6.1 kb transcript levels were increased in RNA enriched for polyadenylated species, the levels of the 4.7 kb band were decreased and also shared a mobility with 28S RNA. A truncated FGF-2 cDNA probe, containing coding but not 5'-untranslated sequences, detected the 6.1 kb transcript but failed to see the 4.7 kb band. The domain responsible for detecting the 4.7 kb band was localized to a G/C-rich region containing 5'-untranslated sequences, by using different fragments of the rat FGF-2 gene, including coding and upstream flanking DNA, as probes. The degree of similarity between sequences of this G/C-rich region of the FGF-2 gene and 28S RNA from rat, human and mouse was sufficient to predict strong cross hybridization. This was confirmed by the detection of a 4.7 kb band in mouse heart RNA with the 'intact' but not truncated rat FGF-2 cDNA probes; a 6.1 kb mouse FGF-2 transcript was detected with both probes. These data indicate that the 4.7 kb RNA detected is not a bona fide FGF-2 transcript, and most likely represents cross hybridization with abundant 28S RNA through G/C-rich non-coding sequences present in the 'intact' rat FGF-2 cDNA. However, sequence comparisons suggest that this result may be the case for other species and might not be restricted to the rat FGF-2 cDNA.

Basic fibroblast growth factor expression precedes flow-induced arterial enlargement

Arteries enlarge in response to increased blood flow, but the molecular signals controlling this enlargement are not well understood. Basic fibroblast growth factor (bFGF) is a potent mitogen for endothelial cells (EC) and smooth muscle cells (SMC) and promotes cellular proliferation and differentiation. In order to determine whether bFGF is expressed in response to increased blood flow in vivo, carotid-jugular arteriovenous fistulas (AVF) were created in Japanese white rabbits. The carotid artery proximal to the fistula was harvested after 1, 3, or 7 days and compared to nonoperated, control carotid arteries. Arterial blood flow increased five- to eightfold in all AVF animals and resulted in a significant increase in wall shear stress. The proximal carotid artery arterial diameter was no different from control after 1 and 3 days (2.3 +/- 0. 1 mm) but enlarged to 2.9 +/- 0.1 mm (P < 0.05) after 7 days. RT-PCR revealed early transcription of bFGF mRNA at 1 and 3 days with increased densitometric band ratio (bFGF/beta-actin) at 7 days. Immunohistochemical analysis revealed bFGF protein localization in EC of control arteries as well as AVF arteries at all time points. SMC and adventitia expression of bFGF was absent in controls, minimal at 1 day, and increased after 3 and 7 days in the experimental groups. Western blotting confirmed the presence of bFGF in samples and transmission immunoelectron microscopy confirmed its nuclear localization. Endothelial cells in vivo express bFGF under both normal and elevated flow conditions. Smooth muscle cells, however, do not express bFGF under normal flow conditions but begin to express bFGF after 1 day of high flow with increased expression after 3 and 7 days. Flow-induced arterial enlargement begins after SMC expression of bFGF. Therefore, bFGF may play a role in arterial enlargement and adaptive remodeling in response to increased flow.

Expression of fibroblast growth factor 2 mRNA in early and advanced gastric cancer

We examined the expression of FGF-2 mRNA in 16 early and 14 advanced gastric cancer by in situ hybridisation to elucidate its role in cancer progression. Anti-sense RNA probes were synthesized by transcribing the subcloned vector with T7 RNA polymerase in the presence of digoxigenin-labeled UTP. FGF-2 mRNA was located mainly in the cytoplasm around the nuclei of endothelial cells, fibroblasts and carcinoma cells. The expression was more frequently in the diffuse type carcinomas (4/7, 57%) than in the intestinal type tumours (5/23, 22%). The survival rates of advanced gastric cancers with FGF-2 mRNA expression were significantly lower than those without FGF-2 mRNA expression (p < 0.01). No significant correlation was seen with other clinicopathological factors. These results suggest that FGF-2 may play an important role for the growth of diffuse type gastric cancers, particularly at their advanced stage.

Adenovirus-mediated gene transfer of basic fibroblast growth factor induces in vitro angiogenesis

To investigate the possibility of adenovirus-mediated gene transfer in the treatment of vascular occlusive diseases, we constructed a replication-deficient recombinant adenovirus vector coding for human basic fibroblast growth factor (bFGF) and examined its effect on the proliferation and differentiation of vascular endothelial cells in vitro. Human umbilical vein endothelial cells (HUVECs) were successfully infected with high efficiency and expressed 18 kD protein which is immunoreactive to anti-bFGF monoclonal antibody. This protein was accumulated mainly in the nuclei of the cells, but was also detected in the culture medium although the complimentary DNA (cDNA) did not contain the classical secreting signal sequence. The proliferation assay of HUVECs infected with bFGF-expressing adenovirus revealed a significant increase in cell number over control. Infection with this virus also enhanced tubular formation of HUVECs on reconstituted basement membrane. Neovascularization and the formation of collateral vessels play important roles in minimizing tissue damage in ischemic disorders. These results imply that the use of bFGF-expressing recombinant adenovirus may be a suitable in vivo gene therapy for ischemic diseases.

High lung inflation increases mRNA levels of ECM components and growth factors in lung parenchyma

Remodeling of pulmonary capillaries occurs after chronic increases in capillary pressure (e.g., mitral stenosis). Also, remodeling of pulmonary arteries begins within 4 h of increased wall stress and is endothelium dependent. We have previously shown that high lung inflation increases wall stress in pulmonary capillaries. This study was designed to determine whether high lung inflation induces remodeling of the extracellular matrix (ECM) in lung parenchyma. Open-chest rabbits were ventilated for 4 h with 9-cmH2O positive end-expiratory pressure (PEEP) on one lung and 1-cmH2O PEEP on the other (High-PEEP group), or with 2-cmH2O PEEP on both lungs (Low-PEEP group). An additional untreated control group was also included. We found increased levels of mRNA in both lungs of High-PEEP rabbits (compared with both the Low-PEEP and untreated groups) for alpha1(III) and alpha2(IV) procollagen, fibronectin, basic fibroblast growth factor, and transforming growth factor-beta1. In contrast, alpha2(I) procollagen and vascular endothelial growth factor mRNA levels were not changed. We conclude that high lung inflation for 4 h increases mRNA levels of ECM components and growth factors in lung parenchyma.

Plausible novel therapeutic strategy of uterine endometrial cancer with reduction of basic fibroblast growth factor secretion by progestin and O-(chloroacetyl-carbamoyl) fumagillol (TNP-470; AGM-1470)

To know the potential of growth, invasion and metastasis of endometrial cancer associated with neovascularization, the effects of sex steroids and O-(chloroacetyl-carbamoyl) fumagillol (TNP-470; AGM-1470) on basic fibroblast growth factor (FGF) expression and secretion and its mRNA expression were investigated in well-differentiated endometrial cancer cell line Ishikawa and in undifferentiated endometrial cancer cell line AN3 CA. Basic FGF expression and secretion and its mRNA expression in Ishikawa cells, but not in AN3 CA cells, were increased by estrogen, while progesterone diminished the estrogen-induced increases. TNP-470 reduced the levels regardless of estrogen treatment in AN3 CA cells. Therefore, basic FGF secretion may be inhibited by progestin in differentiated cells, and by TNP-470 in undifferentiated cells. Since endometrial cancer consists of differentiated and undifferentiated cells as heterogeneity, a combination therapy for endometrial cancer with progestin and TNP470 might be effective.

Antiestrogenic compounds inhibit estrogen-induced expressions of basic fibroblast growth factor and its mRNA in well-differentiated endometrial cancer cells

1. The levels of basic fibroblast growth factor (FGF) expression and secretion and its messenger ribonucleic acid (mRNA) expression in well-differentiated endometrial cancer (Ishikawa) cells were significantly increased by estradiol. 2. This increase was significantly inhibited by tamoxifen, progestins (progesterone, medroxyprogesterone acetate [MPA], and 17 alpha-hydroxyprogesterone), and to some extent danazol, but not by terahydrocortisol and hydrocortisone. 3. Estrogen might stimulate the basic FGF secretion of endometrial cancer cells, at least for neovascularization, and antiestrogenic compounds may inhibit the estrogen-induced event.

Expression of basic fibroblast growth factor and its mRNA in advanced uterine cervical cancers

To know the potential of growth, invasion and metastasis of uterine cervical cancer cells associated with neovascularization, the expression of basic fibroblast growth factor (FGF) and its mRNA in uterine cervical cancers and normal uterine cervices as controls were determined by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction-Southern blot (RT-PCR-SB), respectively. Then, the relations between the expression and the histological grading and clinical staging in cervical cancers were analyzed. The levels of basic FGF and its mRNA were significantly higher in advanced primary uterine cervical cancers, regardless of histological type. Therefore, this status might contribute to the acceleration of growth, invasion, and metastasis with neovascularization in advanced uterine cervical cancers.

Ovarian steroids regulate the expression of basic fibroblast growth factor and its mRNA in fibroblasts derived from uterine endometrium

The role of stromal cells in basic fibroblast growth factor (FGF) supply for endometrial neovascularization during the menstrual cycle was investigated. The concentrations of intracellular and secreted FGF, and FGF mRNA expression were determined in fibroblasts derived from uterine endometrium as a substitute for stromal cells. The influence of sex steroids on protein and mRNA expression was investigated. The concentration of FGF and its mRNA expression in the fibroblasts was significantly increased by oestradiol, and these increased concentrations were diminished by progesterone. It is suggested that oestrogen stimulates FGF secretion from the stromal cells, an effect which is inhibited by progesterone. Therefore, endometrial neovascularization might be partially regulated by stromal-derived FGF under the influence of sex steroids, through a paracrine cell-to-cell interaction.

Increased expression of basic fibroblast growth factor (bFGF) following focal cerebral infarction in the rat

Basic fibroblast growth factor (bFGF) is a polypeptide with potent trophic effects on brain neurons, glia, and endothelial cells. In the current study, we used Northern blotting, in situ hybridization, and immunohistochemical techniques to examine bFGF expression in brain following focal infarction due to permanent occlusion of the proximal middle cerebral artery in mature Sprague-Dawley rats. We found a four-fold increase in bFGF mRNA in tissue surrounding focal infarcts at 1 day after ischemia. In situ hybridization showed that this increase was found throughout several structures in the ipsilateral hemisphere, including frontoparietal, temporal, and cingulate cortex, as well as in caudoputamen, globus pallidus, septal nuclei, nucleus accumbens, and olfactory tubercle. Increased bFGF mRNA expression was associated with cells having the distinct morphological appearance of astroglia in these structures. Immunohistochemistry showed an increase in the size and number of bFGF-immunoreactive (IR) nuclei in these same structures, as well as a shift from nuclear to nuclear plus cytoplasmic localization of immunoreactivity, beginning at 1 day, and peaking at 3 days after ischemia. Double immunostaining identified bFGF-IR cells as astroglia in these structures. (An exception was the piriform cortex, in which both increased bFGF mRNA levels and increased bFGF-IR was found in neurons at 1 day after ischemia). Overall, the peak of increased bFGF expression preceded the peak in expression of the astroglial marker GFAP within the ipsilateral hemisphere. Increased bFGF expression may play an important role in the glial, neuronal, and vascular changes occurring after focal infarction.

Ability of Ovarian Steroids to Regulate the Expression of the Fibroblast Growth Factor Family in Fibroblasts Derived from Uterine Endometrium

Uterine endometrial neovascularization during the menstrual cycle is regulated by a basic fibroblast growth factor (FGF) in the endometrium, consisting of endothelial and stromal cells. Acidic FGF (FGF-1), basic FGF (FGF-2) and hst-1 (FGF-4) proteins also possess angiogenic potency in vivo. Therefore, it is important to improve our understanding of the role of stromal cells in FGF supply for endometrial neovascularization. In this study, we determined FGF-1, -2, and -4 mRNA and FGF-2 by reverse transcription-polymerase chain reaction-Southern blot analysis, and enzyme-linked immunosorbent assay, respectively, in fibroblasts derived from uterine endometria as a substitute for stromal cells. Experimental results indicate that estradiol significanlty increases the levels of intracellular and secreted FGF-2 and its mRNA expression in the FGF family in the fibroblasts. Moreover, progesterone reduces the estradiol-induced increase. Therefore, endometrial neovascularization might be partially regulated by stroma-derived FGF-2 under the influence of sex steroids through a paracrine cell-to-cell interaction. Copyright 1996 S. Karger AG, Basel

Expression of basic fibroblast growth factor and its mRNA in uterine endometrium during the menstrual cycle

To learn more about reproductive neovascularization after menstrual regression of the microvessels in uterine endometrium, the regulation of basic fibroblast growth factor (FGF) and its mRNA expression in the endometria of the menstrual cycle with or without treatment with estradiol dipropionate were determined by enzyme-linked immunosorbent assay (ELISA), and reverse transcription-polymerase chain reaction-Southern blot (RT-PCR-SB), respectively. The endometrial basic FGF level was increased in advance of proliferation, but decreased at the secretory phase. The expression of basic FGF mRNA in endometria during the proliferative phase did not alter, but it was decreased at the secretory phase. Estradiol dipropionate increased the expression of basic FGF and its mRNA in endometria of the secretory phase. Therefore, the constant high level of basic FGF mRNA might contribute to the synthesis and accumulation of basic FGF up to the late proliferative phase, and the accumulated basic FGF might be rapidly consumed in the secretory phase. Furthermore, basic FGF during the proliferative phase could plausibly contribute to capillary neovascularization, which could be regulated by sex steroids.

Mapping protein-protein interactions by affinity-directed mass spectrometry

A precise and rapid method for identifying sites of interaction between proteins was demonstrated; the basis of the method is direct mass spectrometric readout from the complex to determine the specific components of the proteins that interact--a method termed affinity-directed mass spectrometry. The strategy was used to define the region of interaction of a protein growth factor with a monoclonal antibody. A combination of proteolytic digestion and affinity-directed mass spectrometry was used to rapidly determine the approximate location of a continuous binding epitope within the growth factor. The precise boundaries of the binding epitope were determined by affinity-directed mass spectrometric analysis of sets of synthetic peptide ladders that span the approximate binding region. In addition to the mapping of such linear epitopes, affinity-directed mass spectrometry can be applied to the mapping of other types of molecule-molecule contacts, including ligand-receptor and protein-oligonucleotide interactions.

Expression of the rat BFGF antisense RNA transcript is tissue-specific and developmentally regulated

The basic fibroblast growth factor (bFGF) gene locus is transcribed into a number of mRNA transcripts including an antisense mRNA derived from the opposite DNA strand of the bFGF gene. Expression of this natural antisense RNA has been implicated in regulation of the bFGF sense mRNA expression and turnover. In the present study we examined the developmental pattern of expression of the bFGF antisense transcript in fetal and postnatal rat tissues. Northern hybridization with a strand-specific cRNA probe detected a 1.5-kb polyadenylated antisense RNA in all tissues examined except brain, in which two transcripts were detected as a doublet of approximately 1.3-1.5 kb in size. The level of antisense transcript expression was markedly tissue- and age-dependent. In the developing brain, both sense and antisense transcripts were detected by Northern hybridization, but the pattern of their expression was inversely related. The 6.0-kb bFGF sense transcript increased in an age-dependent manner from days 3-30 of postnatal development while the antisense transcript decreased to nearly undetectable levels over the same period. In embryonic (days 15-19) liver, kidney, heart and intestine bFGF antisense RNA expression was low but increased dramatically at parturition, rising 5-10-fold over fetal levels by 10 days of age, then declined slowly to a new steady-state level in adult tissues. The level of antisense RNA in these tissues was much higher than that of bFGF sense mRNA, which was undetectable by Northern analysis. Sense and antisense trancripts were also detected in midgestational (11.5 days) embryos by RT-PCR. Antisense expression did not increase when embryos were explanted and cultured for 48 h (9.5-11.5 days). The apparent reciprocal relationship between the abundance of sense and antisense bFGF transcripts in developing brain supports the possibility of a regulatory role for the antisense transcript in this tissue. There was no evidence for a reciprocal relationship between sense and antisense expression in the other tissues examined, indicating that the relationship between sense and antisense RNA expression may be tissue-specific.

Promotion of gastrulation by maternal growth factor in cultured rabbit blastocysts

Rabbit blastocysts of day 6 post coitus were cultured in a chemically defined, protein-free medium for 24 h. Although the trophoblast continued to grow, the embryonic disc degenerated. Addition of basic fibroblast growth factor (FGF-2, of human recombinant or bovine origin, 10 ng/ml) to the culture medium resulted in significant developmental progress. The embryonic disc became pear-shaped showing a round anterior edge and a posterior node. The primitive streak and Hensen's node indicated that gastrulation had begun. Mesoderm formation was confirmed from histological sections and by localization of the expression of T-gene transcripts in whole-mount preparations. FGF-2 mRNA was detected in both day-6 endometrium and day 6-blastocysts using in vitro translation followed by immunoprecipitation with a monoclonal antibody to FGF-2. In the uterine secretions of day-6 pregnant and pseudopregnant animals, several proteins exhibiting FGF-2 antigenicity were detected on Western blots following two-dimensional gel electrophoresis. As day-6 blastocysts required exogenous FGF-2 in vitro and as FGF-2 of uterine origin is present in the uterine secretion, the maternal growth factor can promote gastrulation in vivo.

Brief exposure to hypoxia induces bFGF mRNA and protein and protects rat cortical neurons from prolonged hypoxic stress

We examined the hypoxic tolerance phenomenon in vitro. Brief exposure to hypoxia induced the production of basic fibroblast growth factor (bFGF) mRNA and protein in rat cortical neurons and protected them from hypoxic injury. Cortical neurons were cultured from 18th-day rat embryos in a serum-free medium and subjected to brief (4 h) and/or prolonged (24 h) hypoxia. Neuronal damage was assessed by quantifying lactate dehydrogenase (LDH) activity in the medium. After brief hypoxia, LDH release was identical to that of the controls, whereas prolonged hypoxia caused a significant increase in LDH release, indicating neuronal death. However, if brief hypoxia was applied 2 days prior to the prolonged hypoxia, no increase in LDH release was observed. The bFGF mRNA expression was assessed with Northern blot and protein immunoreactivity with Western blot analysis. The brief period of hypoxia caused a 2.5-fold increase in bFGF mRNA and considerable bFGF protein expression 1 day later, but prolonged hypoxia caused increase in the expression of bFGF mRNA at 2 days and no protein expression until 3 days after the start of the hypoxia. When cells were subjected to prolonged hypoxia 2 days after brief hypoxia, however, no increase in bFGF mRNA was observed, while bFGF protein was expressed continuously. We also observed that exogenously applied bFGF reduced neuronal injury produced by prolonged hypoxia. The results obtained with this model suggest that brief hypoxia induces bFGF protein and thus tolerance to subsequent lethal hypoxia. Basic FGF might play a role as a tolerance-associated factor in this process. Thus, an in vitro model is useful for assessing the response of cortical neurons to hypoxic stress and for researching new factors related to ischemic tolerance.

Heat-induced bFGF gene expression in the absence of heat shock element correlates with enhanced AP-1 binding activity

Basic fibroblast growth factor (bFGF) has been shown to be a potent mitogen and a promoter of angiogenesis. It has been hypothesized that the expression of the bFGF gene may be induced by stress of various types. To test that hypothesis, we investigated the expression of the bFGF gene during heat treatment in adriamycin-resistant (MCF-7/ADR) and -sensitive (MCF-7) human breast carcinoma cells. Under normal growth conditions, the bFGF mRNA was detected in MCF-7/ADR cells, while it was not detectable in MCF-7 cells by Northern blot analysis. During heating at 41 degrees C, the level of bFGF mRNA increased in MCF-7/ADR cells and the message became detectable in the MCF-7 cell line. However, after continuous heating at 41 degrees C for 24 h, the bFGF mRNA level decreased to control level in MCF-7/ADR cells. Interestingly, simultaneous treatment with heat and 60 micrograms/ml H-7 (1-(isoquinolinylsulfonyl)-2-methylpiperazine, a potent PKC inhibitor) decreased the level of bFGF mRNA in MCF-7/ADR cells. These results suggest that a protein kinase, likely PKC, is involved in the transcriptional regulation of the heat-enhanced bFGF gene expression in human breast carcinoma cells. Although no heat shock element can be identified in the promoter of the bFGF gene, we observed that the AP-1 binding activity to a TPA responsive element (TRE)-like sequence in the promoter of bFGF gene was enhanced by heat, as tested by mobility shift assay. Antibody developed against the c-Jun and c-Fos proteins inhibited the AP-1 binding activity to TRE. Therefore, the AP-1 complex appears to be responsible for the heat-enhanced binding to the TRE-like motif of the bFGF gene. Furthermore, the increased AP-1 binding activity does not require new protein synthesis but activation of the preexisting c-Jun proteins.

The role of angiogenesis in the tumor growth of Syrian hamster pancreatic cancer cell line HPD-NR

BACKGROUND/AIMS

New therapeutic approach is required for pancreatic cancer, one of the most intractable malignancies. The role of angiogenesis in the tumor growth of a Syrian hamster pancreatic cancer cell line HPD-NR, which closely resembles its human counterpart, was investigated.

METHODS

Angiogenic activity was measured as stimulation of growth of human umbilical vein endothelial cells (HUVEC), and angiogenic factors produced by HPD-NR cells were identified by reverse-transcription polymerase chain reaction and Northern blot analysis. Then in vitro and in vivo antitumor effects of a potent angiogenesis inhibitor, O-(chloroacetylcarbamoyl)fumagillol (AGM-1470), were examined.

RESULTS

The conditioned medium of HPD-NR cells stimulated the growth of HUVEC, and four hamster angiogenic factors were detected with an overexpression of transforming growth factor alpha and vascular endothelial growth factor messenger RNAs. AGM-1470 specifically inhibited the growth of HUVEC and that of HPD-NR tumors in vivo with decreased vascularity of the tumors but not the growth of HPD-NR cells in vitro.

CONCLUSIONS

The results suggest that angiogenesis plays an important role in tumor growth of HPD-NR cells and can be a new target of medical therapy for pancreatic cancer.

Regulation of bFGF gene expression and subcellular distribution of bFGF protein in adrenal medullary cells

Basic fibroblast growth factor (bFGF), a potent mitogenic/neurotrophic factor, controls the development and plasticity of many types of neural cells. In adrenal chromaffin cells, the appearance of bFGF protein coincided with the establishment of functional innervation, suggesting induction by trans-synaptic signals. In cultured bovine adrenal medullary cells Western blot analysis revealed 18-, 23-, and 24-kD bFGF isoforms in the cytosolic and nuclear fractions. Stimulation of acetylcholine nicotinic receptors or hormonal angiotensin II receptors or the direct stimulation of adenylate cyclase with forskolin or protein kinase C (PKC) with PMA increased the content of all bFGF isoforms. Increases in the levels of intracellular bFGF did not result in detectable presence of bFGF proteins in culture medium. Instead, bFGF proteins accumulated in the cytoplasm or the nucleus depending on whether PKC or cAMP pathways were activated. The long-term nuclear forskolin-induced accumulation of bFGF was prevented by cycloheximide or by antisense bFGF oligonucleotide and was also accompanied by an increase in bFGF mRNA. We used luciferase reporter plasmids containing the human bFGF promoter to show that the induction of bFGF resulted from transcriptional activation of the bFGF gene and was mediated by regulatory sequences located upstream from its transcription start site. Stimulation of bFGF gene expression by forskolin and PMA was synergistic and was mediated through different promoter regions. The results suggest that stimulation by cAMP and PKC is mediated through novel cis elements. The regulation of bFGF protein content also involves posttranscriptional mechanisms since changes in the levels of individual bFGF isoforms were different depending on whether cells were treated with carbachol or angiotensin II, forskolin, or PMA. The present study indicates that bFGF is an intracrine cytoplasmic-nuclear factor, whose expression is regulated by trans-synaptic and hormonal stimuli and which may act as a direct mediator of genomic responses to afferent stimulation.

Characterization of cDNA encoding basic fibroblast growth factor of the marsupial Monodelphis domestica

We have isolated and characterized a 1,593-bp cDNA containing the coding region of the basic fibroblast growth factor (BFGF) gene of a marsupial, the opossum Monodelphis domestica. The encoded protein is 156 amino acids long. The BFGF gene of M. domestica is 82-87% identical to the BFGF genes of placental mammals at the nucleotide level and 92-93% identical to these genes at the level of the amino acids encoded. Regions of the BFGF molecule important in heparin binding, high-affinity receptor binding, and biologic function are highly conserved between placental mammals and this marsupial. There are several AUG and CUG codons in the 5' region of the marsupial cDNA that may serve as alternate sites of translation initiation; use of these sites would produce amino-terminally extended BFGF proteins. Amino-terminal extensions of BFGF in other species serve as nuclear localization signals. Conserved A+T-rich motifs in the 3' untranslated region of the marsupial mRNA probably serve to regulate mRNA stability. The high degree of evolutionary conservation of BFGF in mammals suggests that the molecule plays an important role in normal growth and development and that stringent control of its activity is essential.

Immunohistochemical study for basic fibroblast growth factor and fibroblast growth factor receptor I in pituitary adenomas

Immunohistochemistry and RT-PCR of basic fibroblast growth factor (bFGF) and one of its receptors (FGFR-I) were performed in pituitary adenomas. Sixty percent of pituitary adenomas showed strong or moderate immunoreactivity to bFGF. The immunoreactivity for FGFR-I in tumor tissues showed positive correlation to that for bFGF (X2 = 6.176, P = 0.0456). Basic FGF-positive cells consisted of pituitary adenoma cells as well as folliculostellate cells and, their distribution was heterogeneous. Expressions of bFGF and FGFR-I were not related to cell proliferation of pituitary adenomas or hormones produced, suggesting that bFGF plays some role other than progression of pituitary adenomas.

Regulatory sequences required for hst-1 expression in embryonal carcinoma cells

The hst-1 gene, which is implicated in mammalian embryonic development and morphological transformation of NIH3T3 cells, is expressed in undifferentiated F9 cells, but not in differentiated F9 and other well-differentiated cells, such as PYS-2, NIH3T3 and HeLa cells. An octamer element present in the 3' untranslated region acts as an enhancer. Although Oct3 is down-regulated when F9 cells are differentiated, transient expression of Oct3 did not enhance the hst-1 promoter activity in HeLa, NIH3T3 or PYS-2 cells. Thus, the role of Oct3 on hst-1 expression remains elusive, and an additional transcription factor which interacts may regulate hst-1 transcription in association with Oct1, Oct3 or both.