Aberrant expression of type I fibroblast growth factor receptor in human pancreatic adenocarcinomas

Acidic and basic fibroblast growth factors are mitogenic polypeptides that are overexpressed in pancreatic cancer. To determine whether fibroblast growth factors may exert direct effects on pancreatic cancer cells in vivo, we compared the expression of the high-affinity type I fibroblast growth factor receptor (FGFR-1) in human pancreatic tissues. In the normal pancreas, FGFR-1 immunostaining was seen mainly in acinar cells. In pancreatic cancers, FGFR-1 was abundant in ductal-like cancer cells which also exhibited many FGFR-1 mRNA in situ hybridization grains. Analysis by the polymerase chain reaction and RNase protection revealed that the 2-immunoglobulin-like and the 3-immunoglobulin-like forms of FGFR-1 were expressed in all tissue samples, and that the 2-immunoglobulin-like form was overexpressed in the cancer tissues by comparison with the normal tissues. These findings suggest that the 2-immunoglobulin-like form of FGFR-1 may contribute to aberrant autocrine and paracrine pathways in pancreatic cancer.     

soc-2 encodes a leucine-rich repeat protein implicated in fibroblast growth factor receptor signaling

Activation of fibroblast growth factor (FGF) receptors elicits diverse cellular responses including growth, mitogenesis, migration, and differentiation. The intracellular signaling pathways that mediate these important processes are not well understood. In Caenorhabditis elegans, suppressors of clr-1 identify genes, termed soc genes, that potentially mediate or activate signaling through the EGL-15 FGF receptor. We demonstrate that three soc genes, soc-1, soc-2, and sem-5, suppress the activity of an activated form of the EGL-15 FGF receptor, consistent with the soc genes functioning downstream of EGL-15. We show that soc-2 encodes a protein composed almost entirely of leucine-rich repeats, a domain implicated in protein-protein interactions. We identified a putative human homolog, SHOC-2, which is 54% identical to SOC-2. We find that shoc-2 maps to 10q25, shoc-2 mRNA is expressed in all tissues assayed, and SHOC-2 protein is cytoplasmically localized. Within the leucine-rich repeats of both SOC-2 and SHOC-2 are two YXNX motifs that are potential tyrosine-phosphorylated docking sites for the SEM-5/GRB2 Src homology 2 domain. However, phosphorylation of these residues is not required for SOC-2 function in vivo, and SHOC-2 is not observed to be tyrosine phosphorylated in response to FGF stimulation. We conclude that this genetic system has allowed for the identification of a conserved gene implicated in mediating FGF receptor signaling in C. elegans.     

Cholecystokinin B-type receptor signaling is involved in human pancreatic cancer cell growth

Cholecystokinin (CCK) is known to stimulate pancreatic cancer cell growth, but no detailed CCK receptor subtype characterization and investigation of CCK receptor-mediated cellular responses in human pancreatic cancer cells have been reported thus far. In this study, CCK binding sites were identified in human pancreatic cancer cells (MIA-PaCa-2) using radioligand binding studies. Pharmacological characterization demonstrated a single class of high-affinity CCK sites on MIA-PaCa-2 cells (326 +/- 18 pM, receptor density 16.9 +/- 2.3 fmol/mg protein). These CCK binding sites displayed a typical CCKB binding profile as shown in competition studies by using different CCK-related compounds and non-peptide CCK antagonists discriminating between CCKA and CCKB sites. CCKB receptor-connected effector systems have been characterized in MIA-PaCA-2 cells, and their involvement in CCK-8S-induced proliferative effects on MIA-PaCa-2 cells has been demonstrated.     

Repression of hedgehog signaling and BMP4 expression in growth plate cartilage by fibroblast growth factor receptor 3

Fibroblast growth factor receptor 3 (FGFR3) is a key regulator of skeletal growth and activating mutations in Fgfr3 cause achondroplasia, the most common genetic form of dwarfism in humans. Little is known about the mechanism by which FGFR3 inhibits bone growth and how FGFR3 signaling interacts with other signaling pathways that regulate endochondral ossification. To understand these mechanisms, we targeted the expression of an activated FGFR3 to growth plate cartilage in mice using regulatory elements from the collagen II gene. As with humans carrying the achondroplasia mutation, the resulting transgenic mice are dwarfed, with axial, appendicular and craniofacial skeletal hypoplasia. We found that FGFR3 inhibited endochondral bone growth by markedly inhibiting chondrocyte proliferation and by slowing chondrocyte differentiation. Significantly, FGFR3 downregulated the Indian hedgehog (Ihh) signaling pathway and Bmp4 expression in both growth plate chondrocytes and in the perichondrium. Conversely, Bmp4 expression is upregulated in the perichondrium of Fgfr3-/- mice. These data support a model in which Fgfr3 is an upstream negative regulator of the hedgehog (Hh) signaling pathway. Additionally, Fgfr3 may coordinate the growth and differentiation of chondrocytes with the growth and differentiation of osteoprogenitor cells by simultaneously modulating Bmp4 and patched expression in both growth plate cartilage and in the perichondrium.     

Suppression of matrilysin inhibits colon cancer cell invasion in vitro

Matrilysin is a member of the matrix metalloproteinase gene family, which is believed to play an important role in tumor invasion and metastasis. We examined the effects of over- and under-expression of matrilysin on the ability of colon cancer cells to migrate across an artificial membrane in vitro. Introduction of matrilysin caused colon cancer cells to become more invasive as assessed by an in vitro invasion assay. In contrast, expression of matrilysin was down-regulated by all trans-retinoic acid or by introduction of anti-sense matrilysin in BM314 colon cancer cells. This down-regulation caused these cells to become less invasive. We demonstrated a correlation between matrilysin level and the invasive potential of human colon cancer cells, implying an important role for matrilysin in the control of tumor invasion in vitro.     

Effects of modulation of basic fibroblast growth factor on tumor growth in vivo

BACKGROUND: Recombinant human basic fibroblast growth factor (rHu-bFGF) is known to stimulate proliferation in some tumor cells and to modulate tumor vascularization. PURPOSE: The purpose of this study was to examine the possible role of this agent in the development of tumors. The study was designed to determine the effects of modulating bFGF activity in vivo in tumor models from cell lines with different responses to bFGF and with different content and receptor levels of bFGF. METHODS: Two tumor cell lines (human DLD-2 colon carcinoma and rat C6 glioma) were characterized for bFGF content and bFGF receptor levels by Western blot analysis in cultured cells and by studies of [125I]rHu-bFGF binding to sections from xenografts grown in nude mice. Tumor cell proliferation was monitored after treatment with rHu-bFGF or the DG2 or DE6 IgG monoclonal antibody to rHu-bFGF in culture and in vivo. RESULTS: C6 cells exhibited 7800 high-affinity receptors for rHu-bFGF per cell (dissociation constant [Kd] = 46 pM), while DLD-2 cells lacked high-affinity receptors. rHu-bFGF stimulated [3H]thymidine uptake by C6 cells, but the addition of DG2 IgG prevented this stimulation; rHu-bFGF had no effect on [3H]thymidine incorporation by DLD-2 cells. C6 cells had higher levels of immunoreactive bFGF than did DLD-2 cells. The xenografts from both cell lines exhibited high-affinity [125I]rHu-bFGF binding that was concentrated on vascular-like structures. rHu-bFGF at a dosage of 0.25 mg/kg given intraperitoneally daily for 18 days caused a twofold increase in DLD-2 tumor weight but had little effect on the growth of C6 xenografts. In contrast, daily intravenous injections of DG2 IgG given to mice had no effect on DLD-2 tumor growth but reduced growth of C6 tumors by approximately 30%--a statistically significant difference. CONCLUSIONS: The addition of exogenous rHu-bFGF or of a neutralizing antibody resulted in significant alterations in tumor growth in vivo, which were specific for tumor type and bFGF characteristics. While some of these effects may be mediated by the bFGF-responsive endothelial cells of the tumor vasculature (DLD-2 colon carcinoma), others may result from inhibition of bFGF-dependent tumor cell proliferation (C6 glioma). IMPLICATIONS: Studies that measure tumor blood flow are necessary to confirm that these effects are mediated by changes in tumor vasculature.     

Comparative study in vivo and in vitro of uniformly 14C-labelled and 125I-labelled recombinant fibroblast growth factor 2

Recombinant bovine fibroblast growth factor (FGF2), uniformly labelled with 14C ([14C]FGF2), was purified and showed to be highly stable and to retain full biological activity. Organ distribution of [14C]FGF2 after intravenous injection of young rats was assessed by autoradiography of whole body sections and compared with those obtained with [125I]iodinated FGF2 (125I-FGF2). Thyroid, stomach, intestine, bladder and skin were radioactively labelled only in the case of 125I-FGF2. This tissue-labelling is artefactual, probably due to free iodide binding not observed when using [14C]FGF2. High-resolution autoradiography showed a complex tissue distribution of [14C]FGF2 in kidney and adrenal organs. Incubation of frozen eye sections with [14C]FGF2 showed a specific and high-resolution labelling pattern of ocular tissues. After cellular internalization, [14C]FGF2 was processed into five distinct polypeptides of 16, 14, 8, 7, and 5.5 kDa. The 14-kDa and 7-kDa polypeptides are novel catabolic fragments not detected with radioiodinated FGF2. In terms of stability, tissue distribution specificity, and autoradiographic resolution, [14C]FGF2 proved to have more advantages than 125I-FGF2 for pharmacokinetic and catabolism studies.     

Suppression of fibroblast growth factors 1 and 2 by antisense oligonucleotides in embryonic chick retinal cells in vitro inhibits neuronal differentiation and survival

As retinal histogenesis proceeds there is a pronounced increase in the expression of fibroblast growth factor (FGF), reaching its maximum in the mature retina and largely in terminal differentiated retinal neurons. Recent in vivo evidence suggests that exogenous FGF functions as a differentiation and survival factor for a wide variety of cell types including CNS neurons and that endogenous FGF may perform similar functions. We have examined the consequences of selectively and independently inhibiting FGF1 or FGF2 expression using antisense oligonucleotides in embryonic chick retinal cells, differentiating in vitro. Whether FGF1 or FGF2 expression was inhibited the results were the same: a marked reduction in neuronal photoreceptor cells differentiation, an increase in programmed cell death, but no effects on cell proliferation. Even although these two related factors promote the same final effect on retinal cells, namely, neuronal differentiation and survival, their normal combined activities or levels appear to be important in achieving this effect. Stimulation with either exogenous FGF1 or FGF2 served to increase endogenous levels of both FGF1 and FGF2 and reversed the effects of antisense blockade of either FGF1 or FGF2. Our data suggest that although other sources of FGF exist within the eye, the function of endogenous FGF in differentiating retinal neurons may be to stimulate their differentiation and promote their survival.     

The effect of basic fibroblast growth factor on coronary vascular tone in experimental hypercholesterolemia in vivo and in vitro

Twenty-three patients with symptomatic giant hemangioma of the liver were treated by surgery between 1979 and 1996 at the department of General Surgery, Faculty of Medicine, University of Cukurova. Twenty-three enucleations were performed in 21 patients, left lateral segmentectomy in one patient and enucleation plus left lobectomy in one patient. The tumors were enucleated along the interface between the hemangioma and normal liver tissue. The diameters of the tumors ranged from 5 x 5 to 25 x 15 cm. The mean blood loss for enucleations was 525 ml (range 500-1000 ml). There was no mortality and no postoperative bleeding. Three patients had postoperative complications. Enucleation is the best surgical technique for symptomatic giant hemangioma of the liver. It may be performed with no mortality, low morbidity and the preservation of all normal liver parenchyma.     

Alterations in fibroblast growth factor receptor expression following brain injury

Trichinellosis is a zoonosis caused by parasites of the genus Trichinella. Transmission of trichinellosis to humans has been shown to occur mainly by the ingestion of meat from pigs, bears of foxes parasitized with muscle larvae of this parasite. However, in Europe, the major human outbreaks of the disease have occurred due to the ingestion of parasitized horse meat. Although the larvae were not isolated from the horse meat, the identification of larvae as T. nativa, T. britovi and T. spiralis was done in biopsy samples obtained from infected individuals. More recently T. spiralis muscle larvae have been isolated and identified, for the first time, in muscle tissue of horses slaughtered at an abattoir in the State of Mexico. Furthermore, in ELISA assays using total extracts or TSL-1 antigens, circulating antibodies against Trichinella have been detected in horses slaughtered at abattoirs from various countries in Europe and Mexico. On the other hand, the experimental infection of horses with parasites of the genes Trichinella has been achieved by several research groups and data obtained regarding the kinetics of antibody production in these animals are important in the development of sensitive and specific diagnostic assays for horse trichinellosis. This will allow to determine the frequency of this infection in horses which are used for animal and human feeding. These assays will also be very helpful for designing strategies to control transmission on the disease by horse meat.     

Studies on the expression of fibroblast growth factors and fibroblast growth factor receptors in human prostate cancer

PURPOSE: We tried to clarify the role of fibroblast growth factors (FGFs) and those receptors (FGF-Rs) in cell proliferation of human prostate cancer. METHODS: The mRNA expression of FGF1, FGF2, FGF7, FGF-R1, FGF-R2 (IIIb), and FGF-R2 (IIIc) was investigated by RT-PCR in androgen sensitive cells (LNCaP), androgen-independent cells (PC3) and primary cultured stromal (PS) and epithelial cells (PE) from benign prostatic hyperplasia (BPH). Expression of the mRNA of FGF-R1, FGF-R2 (IIIb) and FGF-R2 (IIIc) in human prostate cancer tissue was similarly analyzed. Furthermore, the level of FGF-R1 expression in human prostate cancer was measured by semi-quantitative RT-PCR. RESULTS: FGF-R1 mRNA was detected in LNCaP, PC3 and the primary cultured stromal cells of BPH. FGF-R2 (IIIb) was seen in LNCaP cells and the primary cultured epithelial cells of BPH, while FGF-R2 (IIIc) was only observed in PC3. FGF1 mRNA was expressed in LNCaP and PC3, while FGF2 mRNA was in PC3 alone. The expression of FGF7 mRNA was detected only in the primary cultured stromal cells. Of 17 patients with human prostate cancer, FGF-R2 (IIIb) was detected in 2 and FGF-R2 (IIIc) in 15. Histological type of two cases having FGF-R2 (IIIb) were well differentiated adenocarcinoma. The mRNA levels of FGF-R1 in poorly and moderately differentiated types were significantly higher than those in well differentiated ones (p < 0.05). CONCLUSION: These findings suggest that several changes of expression in FGFs and FGF-Rs may correlate with malignant progression of human prostate cancer.     

Alternative splicing of fibroblast growth factor receptor 2 (FGF-R2) in human prostate cancer

Progression of prostate cancer from an androgen sensitive to androgen insensitive tumor has previously been shown to be accompanied by a change in alternative splicing of fibroblast growth factor receptor 2 (FGF-R2) in a rat model of prostate cancer. This change results in loss of the FGF-R2(IIIb) isoform and predominant expression of the FGF-R2(IIIc) isoform. We sought to determine whether this change in FGF-R2 splicing is also associated with androgen insensitivity in human prostate tumors. We analysed three well characterized human prostate cancer cell lines and three metastatic prostate tumors which have been maintained as xenografts in nude mice. One of the cell lines, LNCaP, and two of the xenografts, DUKAP-1 and DUKAP-2, have been characterized as androgen sensitive, whereas two of the cell lines, DU-145 and PC-3, and one of the xenografts, DU9479, display androgen independent growth. Using an RT-PCR based assay, we demonstrated that progressive loss of the FGF-R2(111b) isoform correlated with androgen insensitivity in these human prostate cancer models. These findings lend support to the hypothesis that that loss of FGF-R2(IIIb) may be one step in a series of events which lead to progression of human prostate cancer.     

A natural kinase-deficient variant of fibroblast growth factor receptor 1

A fibroblast growth factor receptor 1 variant missing 37 amino acids from the carboxy-terminal tyrosine kinase catalytic domain was discovered in human lung fibroblasts and several other human cell lines. The receptor variant binds specifically to acidic fibroblast growth factor but has no tyrosine kinase activity. It was found that cellular transfectants expressing the fibroblast growth factor receptor 1 variant are mitogenically inactive and ligand binding to the receptor causes neither receptor autophosphorylation nor phospholipase C-gamma transphosphorylation. The fibroblast growth factor receptor 1 variant therefore represents an inactive receptor for acidic fibroblast growth factor. Since both kinase and kinase-deficient receptor forms are expressed in cells, it is conceivable that the kinase-deficient receptor plays an important role in regulating cellular responses elicited by acidic fibroblast growth factor stimulation.     

Basic fibroblast growth factor enhances the growth of postnatal neostriatal GABAergic neurons in vitro

Basic fibroblast growth factor (bFGF) significantly enhances the short-term survival of embryonic striatal neurons in vitro but has little effect on the outgrowth of striatal cells compared to neurons from other brain regions. Studies in our laboratory have shown that bFGF protects postnatal striatal cells in vitro from NMDA receptor-induced neurotoxicity. We therefore examined the effects of bFGF on the outgrowth of GABA-containing cells taken from the postnatal (Day 1) caudate-putamen and cultured for up to 3 weeks. In control cultures GABAergic neurons formed three populations based on somatic size and developed the cytoarchitectural features characteristic of dendrites, spines, and axons. In the presence of bFGF (6 pM continuously from the day of plating), small- and medium-sized GABAergic neurons showed significant increases compared to untreated controls in axon-like growth (axon length) at 6 days in culture and in both axon- and dendrite-like neurite growth (axon length and branch order, number of primary dendrites, dendrite length, and dendritic branch order) at 13 and 17 days in culture. Large GABAergic neurons were unaffected by treatment with bFGF. Striatal GABAergic neurons exposed to nerve growth factor (10 ng/ml) were not different from untreated controls. Neuron survival was also unaffected by bFGF treatment at all days in culture examined. Other observations suggested that the neurotrophic effects of bFGF were mediated by a direct action of the growth factor on striatal neurons and not glial cells. First, glial cells (identified by the immunohistochemical localization of glial fibrillary acidic protein) were unaffected by bFGF treatment at the low concentration (6 pM) used to enhance neurite growth, but did significantly proliferate at higher concentrations of bFGF (6 nM). Second, immunoreactive bFGF receptor protein was localized predominantly to the somata and processes of striatal neurons and not to glial cells in the cultures. Finally, when neurons from control cultures were briefly exposed (1 to 4 h) to bFGF at concentrations which were neurotrophic, a marked elevation in the immediate early gene protein c-fos was observed by immunohistochemistry in the nuclei of neurons, including GABAergic cells.(ABSTRACT TRUNCATED AT 400 WORDS)     

Nitric oxide inhibits LPS-induced tumor necrosis factor synthesis in vitro and in vivo

The effect of nitric oxide (NO) on LPS-stimulated TNF-alpha synthesis has been studied in vitro and in vivo. The synthesis of TNF-alpha in J774 macrophages stimulated with LPS (0.1 microgram/ml) was increased in concentration-related fashion by NO synthase inhibitor L-NMMA (3-30-300 microM) and reduced by either L-arginine (3-30-300 microM) or the NO donor SIN-1 (1-10-100 microM). The level of TNF-alpha in the serum of LPS-challenged rats (6mg/kg/i.p.) was increased in animals pre-treated s.c. with L-NMMA (10 and 50mg/kg) and reduced in those given L-arginine (100 and 300mg/kg). These results show a negative feedback mechanism exhibited by NO on TNF-alpha synthesis suggesting an important regulatory link between NO and TNF-alpha in pathological processes.     

Small molecule inhibitors of the platelet-derived growth factor receptor, the fibroblast growth factor receptor, and Src family tyrosine kinases

The inhibition of tyrosine kinases involved in growth factor signal transduction pathways represents an attractive strategy for controlling aberrant cellular growth. Over the last 4-5 years, there have been numerous reports on the discovery of small molecule inhibitors for potential therapeutic applications to a number of proliferative diseases, principally cancer and restenosis, where the over-expression of certain tyrosine kinases has been demonstrated. These include, amongst others, the platelet-derived growth factor receptor, the fibroblast growth factor receptor, and the nonreceptor c-Src tyrosine kinase. This review compiles published reports and patent filings from 1995 to mid-1997 that include data directly related to inhibition of the platelet-derived growth factor receptor, fibroblast growth factor receptor, and Src family tyrosine kinases. Potential clinical applications for selected classes of tyrosine kinase inhibitors reviewed herein will likely depend on the demonstration of meaningful activity in a variety of therapeutic targets in animal models.     

Brain-derived neurotrophic factor and basic fibroblast growth factor downregulate NMDA receptor function in cerebellar granule cells

Evidence has accumulated to suggest that the NMDA glutamate receptor subtype plays an important role in neuronal degeneration evoked by hypoxia, ischemia, or trauma. Cerebellar granule cells in culture are vulnerable to NMDA-induced neuronal excitotoxicity. In these cells, brain-derived neurotrophic factor (BDNF) and basic fibroblast growth factor (FGF2) prevent the excitotoxic effect of NMDA. However, little is known about the molecular mechanisms underlying the protective properties of these trophic factors. Using cultured rat cerebellar granule cells, we investigated whether BDNF and FGF2 prevent NMDA toxicity by downregulating NMDA receptor function. Western blot and RNase protection analyses were used to determine the expression of the various NMDA receptor subunits (NR1, NR2A, NR2B, and NR2C) after BDNF or FGF2 treatment. FGF2 and BDNF elicited a time-dependent decrease in the expression of NR2A and NR2C subunits. Because NMDA receptor activation leads to increased intracellular Ca2+ concentration ([Ca2+]i), we studied the effect of the BDNF- and FGF2-induced reduction in NR2A and NR2C synthesis on the NMDA-evoked Ca2+ responses by single-cell fura-2 fluorescence ratio imaging. BDNF and FGF2 reduced the NMDA-mediated [Ca2+]i increase with a time dependency that correlates with their ability to decrease NR2A and NR2C subunit expression, suggesting that these trophic factors also induce a functional downregulation of the NMDA receptor. Because sustained [Ca2+]i is believed to be causally related to neuronal injury, we suggest that BDNF and FGF2 may protect cerebellar granule cells against excitotoxicity by altering the NMDA receptor-Ca2+ signaling via a downregulation of NMDA receptor subunit expression.