cDNA sequence of human transforming gene hst and identification of the coding sequence required for transforming activity

Fibroblast Growth Factors in Cardiovascular Disease

Despite advancements in managing traditional cardiovascular risk factors, many cardiovascular diseases (CVDs) persist. Fibroblast growth factors (FGFs) have emerged as potential diagnostic markers and therapeutic targets for CVDs. FGF1, FGF2, and FGF4 are primarily used for therapeutic angiogenesis. Clinical applications are being explored based on animal studies using approaches such as recombinant protein administration and adenovirus-mediated gene delivery, targeting patients with coronary artery disease and lower extremity arterial disease. Although promising results have been observed in animal models and early-stage clinical trials, further studies are required to assess their therapeutic potential. The FGF19 subfamily, consisting of FGF19, FGF21, and FGF23, act via endocrine signaling in various organs. FGF19, primarily expressed in the small intestine, plays important roles in glucose, lipid, and bile acid metabolism and has therapeutic potential for metabolic disorders. FGF21, found in various tissues, improves glucose metabolism and insulin sensitivity, suggesting potential for treating obesity and diabetes. FGF23, primarily secreted by osteocytes, regulates vitamin D and phosphate metabolism and serves as an important biomarker for chronic kidney disease and CVDs. Thus, FGFs holds promise for both therapeutic and diagnostic applications in metabolic and cardiovascular diseases. Understanding the mechanisms of FGF may pave the way for novel strategies to prevent and manage CVDs, potentially addressing the limitations of current treatments. This review explores the roles of FGF1, FGF2, FGF4, and the FGF19 subfamily in maintaining cardiovascular health. Further research and clinical trials are crucial to fully understand the therapeutic potential of FGFs in managing cardiovascular health.

Growth Factor Roles in Soft Tissue Physiology and Pathophysiology

Repair and healing of injured and diseased tendons has been traditionally fraught with apprehension and difficulties, and often led to rather unsatisfactory results. The burgeoning research field of growth factors has opened new venues for treatment of tendon disorders and injuries, and possibly for treatment of disorders of the aorta and major arteries as well. Several chapters in this volume elucidate the role of transforming growth factor β (TGFß) in pathogenesis of several heritable disorders affecting soft tissues, such as aorta, cardiac valves, and tendons and ligaments. Several members of the bone morphogenetic group either have been approved by the FDA for treatment of non-healing fractures or have been undergoing intensive clinical and experimental testing for use of healing bone fractures and tendon injuries. Because fibroblast growth factors (FGFs) are involved in embryonic development of tendons and muscles among other tissues and organs, the hope is that applied research on FGF biological effects will lead to the development of some new treatment strategies providing that we can control angiogenicity of these growth factors. The problem, or rather question, regarding practical use of imsulin-like growth factor I (IGF-I) in tendon repair is whether IGF-I acts independently or under the guidance of growth hormone. FGF2 or platelet-derived growth factor (PDGF) alone or in combination with IGF-I stimulates regeneration of periodontal ligament: a matter of importance in Marfan patients with periodontitis. In contrast, vascular endothelial growth factor (VEGF) appears to have rather deleterious effects on experimental tendon healing, perhaps because of its angiogenic activity and stimulation of matrix metalloproteinases-proteases whose increased expression has been documented in a variety of ruptured tendons. Other modalities, such as local administration of platelet-rich plasma (PRP) and/or of mesenchymal stem cells have been explored extensively in tendon healing. Though treatment with PRP and mesenchymal stem cells has met with some success in horses (who experience a lot of tendon injuries and other tendon problems), the use of PRP and mesenchymal stem cells in people has been more problematic and requires more studies before PRP and mesenchymal stem cells can become reliable tools in management of soft tissue injuries and disorders.

Fibroblast growth factors, old kids on the new block

The fibroblast growth factors (FGFs) are a family of cell intrinsic regulatory peptides that control a broad spectrum of cellular activities. The family includes canonic FGFs that elicit their activities by activating the FGF receptor (FGFR) tyrosine kinase and non-canonic members that elicit their activities intracellularly and via FGFR-independent mechanisms. The FGF signaling axis is highly complex due to the existence of multiple isoforms of both ligands and receptors, as well as cofactors that include the chemically heterogeneous heparan sulfate (HS) cofactors, and in the case of endocrine FGFs, the Klotho coreceptors. Resident FGF signaling controls embryonic development, maintains tissue homeostasis, promotes wound healing and tissue regeneration, and regulates functions of multiple organs. However, ectopic or aberrant FGF signaling is a culprit for various diseases, including congenital birth defects, metabolic disorder, and cancer. The molecular mechanisms by which the specificity of FGF signaling is achieved remain incompletely understood. Since its application as a druggable target has been gradually recognized by pharmaceutical companies and translational researchers, understanding the determinants of FGF signaling specificity has become even more important in order to get into the position to selectively suppress a particular pathway without affecting others to minimize side effects.

Lip, a human gene detected by transfection of DNA from a human liposarcoma encodes a protein with homology to regulators of small g proteins

Purpose/Method. Transfection experiments have been used to identify activated oncogenes in a wide variety of tumour types. Here we describe the use of transfection experiments utilizing DNA from a human pleomorphic liposarcoma to identify a novel gene, designated lip which maps to chromosome 19.Results. lip was expressed in all sarcoma cell lines examined and a wide variety of normal tissues. Sequencing of cDNAs prepared from transcripts of the normal lip gene indicates that lip is predicted to encode a 966 amino acid protein with a region of homology to proteins such as vav, dbl, lbc and ect-2 which act as GDP-GTP exchange factors for the RAS superfamily of small GTP-binding proteins, and the N-terminal 830 amino acids are identical to the recently identified gene p115-RhoGEF, an exchange factor for RHOA. In transfectants, lip has undergone a rearrangement which results in C-terminal truncation of the predicted LIP protein. However, we failed to detect this alteration in the primary liposarcoma used in the original transfection experiments, or in other sarcoma specimens examined.Discussion. When considered together, these observations suggest that transforming lip sequences represent an alternatively spliced form of p115-RhoGEF that is activated for transformation by C-terminal truncation during transfection, and is not widely involved in sarcoma development.

Pleiotropic function of FGF-4: its role in development and stem cells

Fibroblast growth factors (FGFs) were initially recognized as fibroblast-specific growth factor, and it is now apparent that these growth factors regulate multiple biological functions. The diversity of FGFs function is paralleled by the emerging diversity of interactions between FGF ligands and their receptors. FGF-4 is a member of the FGF superfamily and is a mitogen exhibiting strong action on numerous different cell types. It plays a role in various stages of development and morphogenesis, as well as in a variety of biological processes. Recent studies reveal the molecular mechanisms of FGF-4 gene regulation in mammalian cells, which is involved in the developmental process. Furthermore, FGF-4 also acts on the regulation of proliferation and differentiation in embryonic stem cells and tissue stem cells. In this review, we focus on the diverse biological functions of FGF-4 in the developmental process and also discuss its putative roles in stem cell biology.

Fibroblast growth factor 4 and its novel splice isoform have opposing effects on the maintenance of human embryonic stem cell self-renewal

Human embryonic stem cells (HESCs) are unique in their capacity to self-renew while remaining pluripotent. This undifferentiated state must be actively maintained by secreted factors. To identify autocrine factors that may support HESC growth, we have taken a global genetic approach. Microarray analysis identified fibroblast growth factor 4 (FGF4) as a prime candidate for autocrine signaling. Furthermore, the addition of recombinant FGF4 to HESCs supports their proliferation. We show that FGF4 is produced by multiple undifferentiated HESC lines, along with a novel fibroblast growth factor 4 splice isoform (FGF4si) that codes for the amino-terminal half of FGF4. Strikingly, although FGF4 supports the undifferentiated growth of HESCs, FGF4si effectively counters its effect. Furthermore, we show that FGF4si is an antagonist of FGF4, shutting down FGF4-induced Erk1/2 phosphorylation. Expression analysis shows that both isoforms are expressed in HESCs and early differentiated cells. However, whereas FGF4 ceases to be expressed in mature differentiated cells, FGF4si continues to be expressed after cell differentiation. Targeted knockdown of FGF4 using small interfering RNA increased differentiation of HESCs, demonstrating the importance of endogenous FGF4 signaling in maintaining their pluripotency. Taken together, these results suggest a growth-promoting role for FGF4 in HESCs and a putative feedback inhibition mechanism by a novel FGF4 splice isoform that may serve to promote differentiation at later stages of development.

Molecular biology of the hst-1 gene

The hst-1 gene (or HSTF1 by human gene nomenclature) was originally identified in our laboratory by an NIH/3T3 focus formation assay using DNA from a human gastric cancer. Sequence analysis predicted the hst-1 product to be a novel growth factor with 30-50% homology with six other heparin-binding growth factors: basic and acidic fibroblast growth factors (FGFs), the int-2 protein, FGF5, the hst-2/FGF6 protein and keratinocyte growth factor (KGF). A recombinant hst-1 protein was synthesized in silkworm cells and found to be a potent heparin-binding mitogen for murine fibroblasts and human vascular endothelial cells. Although hst-1 expression cannot be detected in most cancer cells, including gastric cancers, it is expressed in mouse embryos and in some germ cell tumours. Both hst-1 and int-2 are located on band q13.3 of human chromosome 11 within a distance of 35 kbp; in the mouse genome these two genes are separated by less than 20 kbp. They are differentially transcribed in the F9 mouse teratocarcinoma cell line; hst-1 is expressed in undifferentiated stem cells and int-2 in differentiated endodermal cells. The hst-1 and int-2 genes were coamplified in a variety of cancer cells, most notably in more than 50% of oesophageal cancers.

Keratinocyte growth factor expression and activity in cancer: implications for use in patients with solid tumors

Keratinocyte growth factor (KGF) is a locally acting epithelial mitogen that is produced by cells of mesenchymal origin and has an important role in protecting and repairing epithelial tissues. Use of recombinant human KGF (palifermin) in patients with hematologic malignancies reduces the incidence and duration of severe oral mucositis experienced after intensive chemoradiotherapy. These results suggest that KGF may be useful in the treatment of patients with other kinds of tumors, including those of epithelial origin. However, its application in this context raises issues that were not pertinent to its use in hematologic cancer because epithelial tumor cells, unlike blood cells, often express the KGF receptor (FGFR2b). Thus, it is important to examine whether KGF could promote the growth of epithelial tumors or protect such tumor cells from the effects of chemotherapy agents. Analyses of KGF and FGFR2b expression in tumor specimens and of KGF activity on transformed cells in vitro and in vivo do not indicate a definitive role for KGF in tumorigenesis. On the contrary, restoring FGFR2b expression to certain malignant cells can induce cell differentiation or apoptosis. However, other observations suggest that, in specific situations, KGF may contribute to epithelial tumorigenesis. Thus, further studies are warranted to examine the nature and extent of KGF involvement in these settings. In addition, clinical trials in patients with solid tumors are underway to assess the potential benefits of using KGF to protect normal tissue from the adverse effects of chemoradiotherapy and its possible impact on clinical outcome.

Transcription factor Ets-1 regulates fibroblast growth factor-1-mediated angiogenesis in vivo: role of Ets-1 in the regulation of the PI3K/AKT/MMP-1 pathway

We previously demonstrated that a modified secreted form of fibroblast growth factor 1 (FGF-1), a prototypic member of the FGF family, has the ability to stimulate angiogenesis in an in vivo model of angiogenesis, the so-called chick chorioallantoic membrane assay or CAM. We recently defined the importance of the phosphatidylinositol 3-kinase/AKT pathway in FGF-1-mediated angiogenesis in this model using specific pharmacological inhibitors. In our continuing efforts to define the molecular signaling pathway regulating FGF-1-induced angiogenesis in vivo, we utilized a transcription factor activity assay and identified transcription factor Ets-1 as a critical effector of FGF-1-induced angiogenesis. Both activity and mRNA expression levels of the Ets-1 molecule were increased in response to FGF-1 overexpression in CAMs, as documented by electrophoretic mobility shift assay (gel shift) and reverse transcription real-time PCR techniques, respectively. Furthermore, the delivery of Ets-1 antisense (AS) into CAM tissues effectively reduced angiogenesis in the CAM assay. In addition, both Ets-1 AS-treated chicken CAMs and cultured endothelial cells exhibited a reduction in matrix metalloproteinase 1 gene expression levels. The Ets-1 AS-treated endothelial cells also demonstrated a reduction in migration. These data suggest that Ets-1 activation is a requisite for FGF-1-mediated angiogenesis in vivo. Therefore, Ets-1 might be a potential target for the generation of inhibitor drugs for the treatment of FGF-dependent pathological angiogenesis such as metastatic tumors, rheumatoid arthritis and diabetic retinopathy.

Common structure of rare replication-deficient E1-positive particles in adenoviral vector batches

The use of the PER.C6 adenovirus packaging cell line in combination with a designated vector plasmid system, whereby the cell line and vector with E1 deleted have no sequence overlap, eliminates the generation of replication-competent adenovirus during vector production. However, we have found cytopathic effect (CPE)-inducing particles in 2 out of more than 40 large-scale manufacturing lots produced in PER.C6 cells. The CPE inducer was detected at a frequency of 1 event in 7.5 x 10(12) vector particles. Despite amplification, it was not readily purified, indicating that the agent itself is replication deficient and requires the parental recombinant adenovirus serotype 5 (rAd5) vector for replication and packaging. Therefore, we designated the agent as a helper-dependent E1-positive region containing viral particle (HDEP). Here, we report the molecular structure of the HDEP genome, revealing an Ad comprised of E1 sequences derived from PER.C6 cells flanked by inverted terminal repeat, packaging signal, and transgene sequences. These sequences form a palindromic structure devoid of E2, E3, E4, and late genes. Since only 5 bp were shared between E1 sequences in the PER.C6 genome and viral vector sequences, the data strongly suggested that insertion of genomic DNA into an adenoviral genome had occurred essentially via nonhomologous recombination. HDEPs have been found in unrelated virus batches and appear to share a common structure that may explain their mechanism of generation. This finding allowed development of an HDEP assay to screen batches of rAd5 produced on the PER.C6 cell line and resulted in detection of seven HDEP agents from four different transgene-virus vector constructs in separate batches of Ad.

Fibroblast growth factor (FGF)-4 can induce proliferation of cardiac cushion mesenchymal cells during early valve leaflet formation

While much has been learned about how endothelial cells transform to mesenchyme during cardiac cushion formation, there remain fundamental questions about the developmental fate of cushions. In the present work, we focus on the growth and development of cushion mesenchyme. We hypothesize that proliferative expansion and distal elongation of cushion mesenchyme mediated by growth factors are the basis of early valve leaflet formation. As a first step to test this hypothesis, we have localized fibroblast growth factor (FGF)-4 protein in cushion mesenchymal cells at the onset of prevalve leaflet formation in chick embryos (Hamburger and Hamilton stage 20-25). Ligand distribution was correlated with FGF receptor (FGFR) expression. In situ hybridization data indicated that FGFR3 mRNA was confined to the endocardial rim of the atrioventricular (AV) cushion pads, whereas FGFR2 was expressed exclusively in cushion mesenchymal cells. FGFR1 expression was detected in both endocardium and cushion mesenchyme as well as in myocardium. To determine whether the FGF pathways play regulatory roles in cushion mesenchymal cell proliferation and elongation into prevalvular structure, FGF-4 protein was added to the cushion mesenchymal cells explanted from stage 24-25 chick embryos. A significant increase in proliferative ability was strongly suggested in FGF-4-treated mesenchymal cells as judged by the incorporation of 5'-bromodeoxyuridine (BrdU). To determine whether cushion cells responded similarly in vivo, a replication-defective retrovirus encoding FGF-4 with the reporter, bacterial beta-galactosidase was microinjected into stage 18 chick cardiac cushion mesenchyme along the inner curvature where AV and outflow cushions converge. As compared with vector controls, overexpression of FGF-4 clearly induced expansion of cushion mesenchyme toward the lumen. To further test the proliferative effect of FGF-4 in cardiac cushion expansion in vivo (ovo), FGF-4 protein was microinjected into stage 18 chick inner curvature. An assay for BrdU incorporation indicated a significant increase in proliferative ability in FGF-4 microinjected cardiac cushion mesenchyme as compared with BSA-microinjected controls. Together, these results suggest a role of FGF-4 for cardiac valve leaflet formation through proliferative expansion of cushion mesenchyme.

Biodegradable gelatin hydrogel potentiates the angiogenic effect of fibroblast growth factor 4 plasmid in rabbit hindlimb ischemia

OBJECTIVES

We investigated the potentiation of gene therapy using fibroblast growth factor 4 (FGF4)-gene by combining plasmid deoxyribonucleic acid (DNA) with biodegradable gelatin hydrogel (GHG).

BACKGROUND

Virus vectors transfer genes efficiently but are biohazardous, whereas naked DNA is safer but less efficient. Deoxyribonucleic acid charges negatively; GHG has a positively charged structure and is biodegradable and implantable; FGF4 has an angiogenic ability.

METHODS

The GHG-DNA complex was injected into the hindlimb muscle (63 mice and 55 rabbits). Gene degradation was evaluated by using (125)I-labeled GHG-DNA complex in mice. Transfection efficiency was evaluated with reverse-transcription nested polymerase chain reaction and X-Gal histostaining. The therapeutic effects of GHG-FGF4-gene complex (GHG-FGF4) were evaluated in rabbits with hindlimb ischemia.

RESULTS

Gelatin hydrogel maintained plasmid in its structure, extending gene degradation temporally until 28 days after intramuscular delivery, and improving transfection efficiency. Four weeks after gene transfer, hindlimb muscle necrosis was ameliorated more markedly in the GHG-FGF4 group than in the naked FGF4-gene and GHG-beta-galactosidase (control) groups (p < 0.05, Kruskal-Wallis test). Synchrotron radiation microangiography (spatial resolution, 20 microm) and flow determination with microspheres confirmed significant vascular responsiveness to adenosine administration in the GHG-FGF4 group, but not in the naked FGF4-gene and the control.

CONCLUSIONS

The GHG-FGF4 complex promoted angiogenesis and blood flow regulation of the newly developed vessels possibly by extending gene degradation and improving transfection efficiency without the biohazard associated with viral vectors.

A single short stretch of homology between adenoviral vector and packaging cell line can give rise to cytopathic effect-inducing, helper-dependent E1-positive particles

An undesirable byproduct from recombinant adenoviral vectors is the emergence of replication competent adenovirus (RCA) that result from rare homologous recombination events between the viral E1-containing (permissive) mammalian host cell genome and the virus itself, restoring the E1 gene to the viral genome. To reduce or eliminate the problem of RCA, we evaluated production of a first generation Ad5 vector (Ad5FGF4) in the cell line PER.C6. This E1-transformed human cell line contains only Ad5 nucleotides 459-3510, which precludes double crossover-type homologous recombination because the Ad5FGF-4 only contains 5' Ad5 sequence up to nucleotide 453. The Ad5FGF4 vector does, however, retain 177 nucleotides of the 3' end of the E1B-55K gene that are also present in PER.C6. With only this single region of homology between vector and cell line, we were surprised to detect virus-specific cytopathic effects (CPE) in our cell-based assay for RCA. This CPE-inducing agent was amplified in nonpermissive A549 cells but also supported amplification of the parental Ad5FGF-4. Because we were unable to isolate the CPE-inducing agent in pure form we first identified it as atypical RCA. Polymerase chain reaction (PCR) and Southern blot experiments identified viral DNA segments in which recombination had occurred between the 177 nucleotides of E1B present in both Ad5FGF-4 and PER.C6. The atypical RCA genomes contain a copy of the original (PGK promoter-E1 gene carrying) plasmid used in the construction of the PER.C6 cell line and they retained the parental FGF-4 transgene. However, significant deletions occurred within the recombined genomes in compensation for the large insertion from PER.C6 sequences and resulted in the loss of essential viral genes. This deletion renders these recombinant viruses replication defective, requiring helper functions from remaining parental Ad5FGF-4 for amplification. These atypical RCA entities may be more properly designated as helper-dependent E1-positive particles (HDEPs). This finding shows the importance of avoiding the use of "nonmatched" vectors where any overlap exists between the recombinant vector and E1 sequences in the packaging cell line. The cloning of the FGF-4 transgene into an adenoviral vector specifically "matched" for PER.C6 (lacking the 177 nucleotide region of homology) has allowed extensive virus propagation (Ad5.1FGF-4) with no CPE- or HDEP-like events yet detected.

Coevolution of HMG domains and homeodomains and the generation of transcriptional regulation by Sox/POU complexes

The highly conserved homeodomains and HMG domains are components of a large number of proteins that play a role in the transcriptional regulation of gene expression during embryogenesis. Both the HMG domain and the homeodomain serve as interfaces for factor interactions with DNA, as well as with other proteins, and it is likely that the high degree of structural and sequence conservation within these domains reflects the conservation of basic aspects of these interactions. Classical HMG domain proteins have an ancient origin, being found in all eukaryotes, and are thought to have given rise to the metazoan-specific class of HMG domain proteins called the Sox proteins. Similarly, the metazoan-specific POU domain proteins are thought to have arisen from genes encoding ancestral homeodomain proteins. In this review, we summarize several examples of different HMG-homeodomain interactions that illustrate not only the ancient origin of each of these protein families, but also their relationship to each other, and discuss how coevolution of HMG and homeodomains may have lead to creation of the specialized Sox/POU protein complexes. Using the FGF-4 gene as an example, we also speculate on how coevolution of regulatory Sox/POU target DNA sequences may have occurred, and how the summation of these changes may have lead to the emergence of new developmental pathways.

Adenovirus-mediated transfer of HST-1/FGF-4 gene protects mice from lethal irradiation

Intraperitoneal injection of a replication-deficient adenovirus containing the HST-1 (FGF-4) gene (Adex1HST-1) increased peripheral platelet counts in mice, and also effectively prevented experimentally induced thrombocytopenia. Here, we report the therapeutic potential of Adex1HST-1 on severely injured mice after exposure to otherwise lethal irradiation. Eighteen out of 20 mice that received Adex1HST-1 prior to gamma-irradiation (9 Gy) survived, while all the 20 mice with prior administration of control adenoviruses died after irradiation (P<0.0001). Hematological and histopathological analyses revealed that Adex1HST-1 acts as a potent protector against lethal irradiation, which causes injury of intestinal tract as well as myelosuppression in the bone marrow and spleen. These data demonstrate that the protective effects of administration of Adex1HST-1 against irradiation are superior to any other protective effects of cytokines against a lethal dose of irradiation, and that the pre-administration of Adex1HST-1 may be useful for lessening the side effects of currently used chemo- and radio-therapy against cancer.

Anabolic effect of aminoterminally truncated fibroblast growth factor 4 (FGF4) on bone

Fibroblast growth factor 4 (FGF4), a member of the FGF family, plays several important roles in bone development during embryogenesis. Systemic administration of FGF4 increases bone mass in rats, which suggests the potential therapeutic usefulness of this growth factor in treatment for osteopenia and in bone regeneration. We investigated the length of FGF4 required to exert its anabolic effects, because this information may be useful in developing new molecules to mimic the effects of FGF4. Because the active site of FGF family molecules is in the carboxylterminal region, we produced aminoterminally truncated recombinant human FGF4s (rhFGF4s) of different sizes. Human FGF4 cDNA containing almost the full length of the coding region (573 bp, 191 amino acid residues) was inserted into pUC18 vector and then deleted from the 5' end using the ExoIII system. Each of the deleted FGF4 cDNAs was subcloned into a pET29(+) expression vector. Differently sized recombinant proteins were expressed in the BL21(DE3)pLysS Escherichia coli strain and then purified. The growth-stimulative effects on NIH3T3 cells of each recombinant protein were examined by means of MTT colorimetric assay. Full-length and the shortened recombinant proteins, which stimulated NIH3T3 cell growth, were then subcutaneously administered into male ddY mice (6 weeks old) every day for 2 weeks. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DEXA) and peripheral quantitative computed tomography (pQCT). The rhFGF4 of 134 amino acid residues, the region homologous to other members of the FGF family, exerted a growth-stimulative effect on NIH3T3 cells comparable to the full-length version of FGF4; however, the shortest version, with 111 amino acid residues, showed a limited growth-stimulative effect. Systemic administration of the rhFGF4 of 134 amino acid residues increased the bone mineral density (BMD) of femurs at a dose of 0.1 mg/kg, which was comparable to that of the full-length rhFGF4. DEXA analysis, pQCT analysis, soft X-ray photos, and contact microradiographs revealed an increase in femoral trabecular bone in FGF4-treated animals; an increase in bone formation was also evident upon histomorphometric analysis. These results indicate that the region of FGF4 that is homologous to other FGF family members provides a sufficient anabolic effect in bone and that this recombinant protein is potentially useful as a therapeutic agent in bone.

Molecular and biological features of two new human squamous and adenocarcinoma of the lung cell lines

Two human cancer cell lines were established from metastatic lesions of an adenocarcinoma (RAL) and a squamous cell (CAEP) carcinoma of the lung. The clinical histories of the patients from whom the cell lines were derived are reported. The lines were maintained in continuous culture with doubling times of 65 (RAL) and 50 (CAEP) hours. The RAL and CAEP cell lines, whose morphology and ultrastructural features are presented, showed extensively rearranged karyotypes with modal number of 85 (RAL) and 98 (CAEP). In particular, chromosome 2 pentasomy and several clonal markers were evident in the RAL cells, whereas a telomeric deletion of chromosome 1, del (1)(q32), was observed in the CAEP cells. The morphologic data were confirmed by high expression of specific antigens for each histotype. A marked positivity of the neuron-specific enolase (NSE) levels was evident by immunoenzymatic assays in the cell lines cytosol with respect to those present in the respective patient's sera. No amplification or rearrangements were evident in the CMYC, LMYC, NMYC, INT-2, ERBB2, HRAS, KRAS, MOS, HST-1 genes by Southern blotting analysis in each cell line. Point mutations in exon 1 of KRAS and in exon 7 of TP53 were evident by polymerase chain reaction (PCR)-DNA sequencing in the RAL cell line, whereas no alterations were present in the HRAS and RB genes. The four genes studied did not show point mutations in the CAEP cell line. The RAL cell line was resistant to all the drugs tested, whereas the CAEP cells were sensitive to vinblastine. These cell lines may represent useful experimental models to investigate lung cancer biology and anticancer drug response.

Fibroblast growth factors and their receptors

Fibroblast growth factors (FGFs) represent a group of polypeptide mitogens eliciting a wide variety of responses depending upon the target cell type. The knowledge of the cell surface receptors mediating the effects of FGFs has recently expanded remarkably. The complexity of the FGF family and the FGF-induced responses is reflected in the diversity and redundancy of the FGF receptors. In this review, a number of biochemical characteristics and biological properties of the FGF family and its receptors are described and their expression both in normal tissues and in tumours is discussed. Finally we speculate on the targetting of growth inhibition agents to tumours through FGF receptors.

Molecular genetics and in vitro sensitivity of a new human cell line, KKP, from a gastric adenocarcinoma

A new cancer cell line (KKP) was established from an ascitic effusion of an advanced gastric adenocarcinoma, intestinal type. The line has been maintained in continuous monolayer culture with a doubling time of 48 hours for more than 2 years. KKP cells, whose ultrastructural features are presented, showed an aneuploid DNA content, a modal number of 53 chromosomes, and the presence of one double minute chromosome. The karyotype showed trisomies of chromosomes 7, 12, 13, and 14, tetrasomy of chromosome 18, a reciprocal translocation [t(1;20)(q21;p11.2)], and a [t(4;?)] rearrangement. No amplification or rearrangements were evident in the c-MYC, c-ERB B2, H-RAS, INT-2, HST-1, c-MOS, and K-RAS genes, whereas somatic rearrangements were present in the sequences corresponding to c-MET and cyclin E genes by Southern blotting analysis. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis of P53 and RB genes did not reveal alterations or point mutations in the SSCP pattern of conformers. The chemosensitivity pattern assay of the KKP cell line indicated that it was sensitive to cisplatin, etoposide, and doxorubicin and resistant to 4'-hydroperoxycyclophosphamide. The clinical history of the patient from whom the cell line was derived is reported and compared with the results observed in the cell line in vitro. High levels of the tumor-associated antigens CEA (carcinoembryonic antigen) and CA19-9 were evident in the KKP cytosol, whereas the KKP spent culture medium maintained the same low levels of CEA and CA 19-9 found in the patient's serum. This new cell line may represent a useful tool for studying the biology of gastric cancer and for planning new therapeutic approaches.

Chromosomal alterations, biological features and in vitro chemosensitivity of SCLC-R1, a new cell line from human metastatic small cell lung carcinoma

A new human cancer cell line was established from a metastatic lesion of a small cell lung carcinoma (SCLC-R1) and maintained in continuous culture with a doubling time of 62 h. The SCLC-R1 line, whose ultrastructural features are presented, showed a diploid DNA content, a translocation involving chromosome 16 [t(16;?)(q24;?)] and noticeable deletions in the FHIT (fragile histidine triad) region in the short arm of chromosome 3 [del(3)(p14)] and in the telomeric region of the short arm of chromosome 12 [del(12)(p13)]. The involvement of 12p in metastatic small cell lung cancer is reported here for the first time. No amplification or rearrangements were evident in the c-myc, L-myc, N-myc, int-2, c-erbB-2, H-ras, K-ras, c-mos, and hst-1 genes by Southern blot analysis. Wild-type p53, RB, K-ras and H-ras genes were evident by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis. The neuron specific enolase (NSE) level was much higher in the cell line's cytosol than in the patient's serum and the cell line also had high expression of chromogranin A and cytokeratin 19. SCLC-R1 cells were sensitive to cisplatin, carboplatin and doxorubicin. The clinical history of the patient from whom the cell line was derived is reported. The characteristics of this new cell line indicate it to be a useful experimental model to investigate lung cancer biology and anticancer drug response.

Expression and function of FGFs-4, -8, and -9 suggest functional redundancy and repetitive use as epithelial signals during tooth morphogenesis

To elucidate the roles of fibroblast growth factors (FGF) in the regulation of tooth morphogenesis we have analyzed the expression patterns of Fgf-4, -8, and -9 in the developing mouse molar and incisor tooth germs from initiation to completion of morphogenesis by in situ hybridization analysis. The expression of these Fgfs was confined to dental epithelial cells at stages when epithelial-mesenchymal signaling regulates critical steps of tooth morphogenesis. Fgf-8 and Fgf-9 mRNAs were present in the oral epithelium of the first branchial arch at E10 and 1 day later expression became more restricted to the area of presumptive dental epithelium and persisted there until the start of epithelial budding. Fgf-8 mRNAs were not detected later in the developing tooth. Fgf-4 and Fgf-9 expression was upregulated in the primary enamel knot, which is a putative signaling center regulating tooth shape. Subsequently, Fgf-4 and Fgf-9 were expressed in the secondary enamel knots at the sites of tooth cusps. Fgf-9 expression spread from the primary enamel knot within the inner enamel epithelium where it remained until E18. In the continuously growing incisors Fgf-9 expression persisted in the epithelium of the cervical loops. The effects of FGFs were analyzed on the expression of the homeobox-containing transcription factors Msx-1 and Msx-2, which are associated with tissue interactions and regulated by the dental epithelium. Locally applied FGF-4, -8, and -9 stimulated intensely the expression of Msx-1 but not Msx-2 in the isolated dental mesenchyme. We suggest that the three FGFs act as epithelial signals mediating inductive interactions between dental epithelium and mesenchyme during several successive stages of tooth formation. This data suggest roles for FGF-8 and FGF-9 during initiation of tooth development, and for FGF-4 and FGF-9 during regulation of tooth shape. FGF-9 may also be involved in differentiation of odontoblasts. The coexpression of Fgfs with other signaling molecules including Shh and several Bmps and their partly similar effects suggest that the FGFs participate in the signaling networks during odontogenesis.

Prolactinomas express human heparin-binding secretory transforming gene (hst) protein product: marker of tumour invasiveness

BACKGROUND AND OBJECTIVE

We have shown previously that heparin-binding secretory transforming gene (hst) overexpression in rat pituitary cells mediates lactotroph tumour growth and stimulates PRL transcription, and that transforming sequences of the gene, which encode fibroblast growth factor-4 (FGF-4), are expressed in human prolactinomas. To further determine the role of hst in human PRL-secreting adenoma pathogenesis we studied the presence of hst protein in these tumours and other types of human pituitary adenoma.

PATIENTS AND DESIGN

Pituitary adenoma tissue samples were obtained at surgery from 14 patients with PRL-secreting adenomas, 5 patients with GH-secreting tumours, 3 with ACTH-secreting, and 13 patients with nonfunctioning tumours. Two normal pituitary tissue specimens were also studied. Clinical data, including tumour invasiveness assessed by preoperative MRI studies, were available. For hst protein immunolocalization, tumour frozen sections were immunostained with antihuman FGF-4 antibody. Immunoperoxidase staining for the proliferation-related nuclear antigen Ki-67 was performed using MIB-1 monoclonal antibody.

RESULTS

Normal anterior pituitary cells did not contain immunoreactive hst protein. Lactotrophs in five of 14 prolactinomas (36%) stained strongly for hst compared with immunoreactive pituicytes in only one of 21 nonfunctioning, GH-, and ACTH-secreting adenomas (P = 0.05). Immunoreactive hst in adenoma cells was detected in 3 of 5 invasive prolactinomas, and in 2 of 9 noninvasive PRL-cell adenomas. Immunostaining for the proliferation-related antigen Ki-67 showed a higher proliferation index in hst-positive adenomas (3.94 + 0.85%) as compared with those immunonegative for hst (1.98 + 0.7%; P = 0.05).

CONCLUSIONS

hst protein may be directly involved in prolactinoma development or progression, particularly in invasive tumours, probably due to the growth promoting effects of FGF-4.

Synergistic activation of the fibroblast growth factor 4 enhancer by Sox2 and Oct-3 depends on protein-protein interactions facilitated by a specific spatial arrangement of factor binding sites

Octamer binding and Sox factors are thought to play important roles in development by potentiating the transcriptional activation of specific gene subsets. The proteins within these factor families are related by the presence of highly conserved DNA binding domains, the octamer binding protein POU domain or the Sox factors HMG domain. We have previously shown that fibroblast growth factor 4 (FGF-4) gene expression in embryonal carcinoma cells requires a synergistic interaction between Oct-3 and Sox2 on the FGF-4 enhancer. Sox2 and Oct-3 bind to adjacent sites within this enhancer to form a ternary protein-DNA complex (Oct-3*) whose assembly correlates with enhancer activity. We now demonstrate that increasing the distance between the octamer and Sox binding sites by base pair insertion results in a loss of enhancer function. Significantly, those enhancer "spacing mutants" which failed to activate transcription were also compromised in their ability to form the Oct* complexes even though they could still bind both Sox2 and the octamer binding proteins, suggesting that a direct interaction between Sox2 and Oct-3 is necessary for enhancer function. Consistent with this hypothesis, Oct-3 and Sox2 can participate in a direct protein-protein interaction in vitro in the absence of DNA, and both this interaction and assembly of the ternary Oct* complexes require only the octamer protein POU and Sox2 HMG domains. Assembly of the ternary complex by these two protein domains occurs in a cooperative manner on FGF-4 enhancer DNA, and the loss of this cooperative interaction contributes to the defect in Oct-3* formation observed for the enhancer spacing mutants. These observations indicate that Oct-3* assembly results from protein-protein interactions between the domains of Sox2 and Oct-3 that mediate their binding to DNA, but it also requires a specific arrangement of the binding sites within the FGF-4 enhancer DNA. Thus, these results define one parameter that is fundamental to synergistic activation by Sox2 and Oct-3 and further emphasize the critical role of enhancer DNA sequences in the proper assembly of functional activation complexes.

Establishment and characterization of two new cell lines derived from human metastatic breast carcinomas

Two human cancer cell lines (MA 2 and MA 3) were established from pleural effusions of infiltrating ductal carcinomas of the breast. The lines were maintained in continuous monolayer culture with doubling times of 70 (MA 2) and 78 (MA 3) hr for more than two years and possessed extensively rearranged abnormal karyo-types with modal chromosome number of 83 (MA 2) and 81 (MA 3) and DNA index values of 1.65 and 1.77, respectively. No amplifications or rearrangements were evident in the c-myc, int-2, c-erb B2, c-Ha-ras, or hst 1 genes in MA 2 and MA 3 cell lines. The clinical histories of the patients from whom the cell lines were derived are reported and compared with the results observed in the cell lines in vitro. The presence of CEA, CA 15-3, and MCA tumor markers observed in the primary tumor tissues was retained by the established cell lines. While the primary tumor tissues were ER+/PgR borderline+ (MA 2) and ER-/PgR+ (MA 3), the MA 2 line was ER+/PgR- and the MA 3 line remained ER-/PgR+. The MDR P-glycoprotein was not expressed either in primary tumor tissues or in the respective cell lines. High expression of cytokeratins 7, 18, and 19 was evident by immunohistochemical analysis in each cell line. whereas cytokeratins 8 and 17 were poorly or not at all expressed. The treatment history of the patients from whom the cell lines were derived involved CMF followed six months later by novantrone and cisplatin plus VP 16 (MA 2) and FEC followed four years later by CMF (MA 3). The chemosensitivity pattern assay of the cell lines indicated that the MA 2 line was sensitive to doxorubicin, cisplatin, and vinblastine, whereas the MA 3 line was sensitive to doxorubicin and cisplatin. The characteristics of these cell lines indicate them to be a good experimental model to investigate breast cancer biology and anticancer drug response.

Amphibian FGF-1 is structurally and functionally similar to but antigenically distinguishable from its mammalian counterpart

Recent studies have shown that fibroblast growth factors (FGF) play an important role in the diverse cellular mechanisms involved with vertebrate development. One system which has received a great deal of attention is the developing limb in part because of the extensive epithelial-mesenchymal interactions that take place during this process. Because it closely parallels the developmental process of the limb and is a model for wound repair, the phenomenon of amphibian limb regeneration has been used to investigate the role of FGF in these processes. We have recently reported on the cloning and functional characterization of an FGF receptor (FGFR) isolated from amphibian regenerative tissue. In this report, we describe the isolation and characterization of an FGF-1 molecule from the newt, Notophthalmus viridescens. Amino acid sequence comparisons indicate that the newt FGF-1 exhibits between 79 to 83% identity with FGF-1 from mammalian and avian species. The full length cDNA of the newt FGF-1 was cloned into a prokaryotic expression vector and purified from E. coli. Although the newt FGF-1 shares a high degree of primary amino acid sequence similarity with other FGF-1 molecules, the recombinant protein was not detected in a Western blot analysis using a polyclonal antibody directed against mammalian FGF-1. Despite the antigenic divergence, the newt FGF-1 was capable of binding to NIH/3T3 and Chinese hamster ovary cells overexpressing mammalian and amphibian FGFRs with dissociation constants comparable to those reported for mammalian FGF-1. Newt FGF-1 could also be cross-linked to receptors on the surface of NIH/3T3 cells. In addition, it elicits a mitogenic response in NIH/3T3 cells indistinguishable from human recombinant FGF-1.

Evidence that fibroblast growth factors 1 and 4 participate in regulation of cardiogenesis

Previous studies in this laboratory have indicated that the early embryonic chick heart depends on fibroblast growth factor-2 (FGF-2; bFGF), sequentially utilized in paracrine and autocrine fashion, for its growth and development (Sugi and Lough, [1995] Dev. Biol. 168-567-574). This view emanated from immunohistochemical detection of FGF-like antigens in endoderm cells at stage 6, and later in the early myocardium at stage 9+ (Parlow et al. [1991] Dev. Biol. 146:139-147). To identify other members of the FGF family that are expressed by these cells, we have used peptide-generated antisera that specifically recognize FGFs 1 and 4. Like FGF-2, FGFs 1 and 4 were exclusively detected in the endoderm at stage 5+ and later in the myocardium, appearing as punctate cytoplasmic deposits. However, whereas FGF-2 is first detected at stage 9+, FGFs 1 and 4 did not appear until stages 11 and 15, respectively. Expression of all FGFs peaked at stages 18-24, decreasing thereafter in parallel with reduced myocardial cell proliferation. To determine these isoproteins' ability to facilitate the completion of terminal cardiac myocyte differentiation, stage 5+ precardiac mesoderm was cultured in defined medium with purified FGFs. Like FGF-2, as little as 5-10 ng/ml FGF-1 or FGF-4 supported the proliferation and differentiation of precardiac myoblasts, resulting in the formation of a vesicle containing an adherent multilayer of synchronously contractile cells. Evidence that this represented FGF receptor-mediated signaling rather than a nonspecific effect of exogenous FGF was indicated by the ability of sodium chlorate to inhibit FGF-mediated cardiogenesis. These findings are consistent with the hypothesis that, like FGF-2, FGFs 1 and 4 participate in the regulation of early heart development via paracrine and autocrine mechanisms.

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

A new cell line from human infiltrating ductal carcinoma of the breast: establishment and characterization

We established a novel cancer cell line (MAST) from the ascitic fluid of a metastatic infiltrating ductal carcinoma of the breast. The epithelial and neoplastic nature of the MAST cells was confirmed by ultrastructural analysis. The cell line was maintained as a monolayer with a doubling time of about 68 h, and it possessed an abnormal karyotype with a modal chromosome number of 60, a trisomy of chromosome 18 and other unidentified rearranged chromosomes. Among the markers consistently found in MAST metaphases, we noted a t(14; 14) and a very large subtelocentric, a large satellited acrocentric and a very large submetacentric chromosome with striking fluorescent bands. Immunoenzymatic assay demonstrated that the MAST cell line was positive for estrogen and progesterone receptors. The in vitro drug-sensitivity assay showed a marked resistance of the cell line to 5-fluorouracil and 4-hydroperoxycyclophosphamide and a moderate resistance to etoposide and 4'-epidoxorubicin. The molecular analysis showed a four-to sixfold amplification of the c-myc gene and no amplification or rearrangement of the int-2, c-erbB-2, c-Ha-ras, c-mos and hst-1 genes.

Heparin-binding secretory transforming gene (hst) facilitates rat lactotrope cell tumorigenesis and induces prolactin gene transcription

We have shown previously that human prolactinomas express transforming sequences of the heparin-binding secretory transforming gene (hst) which encodes fibroblast growth factor-4 (FGF-4). To elucidate the role of hst in pituitary tumorigenesis we treated primary rat pituitary and pituitary tumor cell cultures with recombinant FGF-4 and also stably transfected pituitary cell lines with full-length human hst cDNA. Transfectants were screened for hst mRNA expression and FGF-4 production. FGF-4 (0.1-50 ng/ml) caused a dose-dependent 2.5-fold increase of prolactin (PRL) secretion (P < 0.001) in GH4 cells and up to 60% (P < 0.05) in primary cultures, while decreasing growth hormone release (P < 0.001). GH4 hst transfectants displayed markedly enhanced basal PRL secretion (threefold, P < 0.001) and also proliferated faster (P < 0.001). FGF-4 treatment of wild-type GH4 cells, transiently transfected with an expression construct (rPRL.luc) containing a luciferase reporter driven by the rPRL promoter, resulted in a dose-dependent increase of up to 3.3-fold in PRL transcriptional activity. Tumors derived from in vivo subcutaneous injection of GH4 hst-transfected cells strongly expressing FGF-4 grew more aggressively as assessed by histologic invasiveness and proliferating cell nuclear antigen staining (P < 0.01). The results indicate that hst overexpression mediates lactotrope tumor growth and potently stimulates PRL synthesis. Thus, hst may directly facilitate prolactinoma development via paracrine or autocrine action of its secreted protein, FGF-4.

Developmental-specific activity of the FGF-4 enhancer requires the synergistic action of Sox2 and Oct-3

Fibroblast growth factor 4 (FGF-4) has been shown to be a signaling molecule whose expression is essential for postimplantation mouse development and, at later embryonic stages, for limb patterning and growth. The FGF-4 gene is expressed in the blastocyst inner cell mass and later in distinct embryonic tissues but is transcriptionally silent in the adult. In tissue culture FGF-4 expression is restricted to undifferentiated embryonic stem (ES) cells and embryonal carcinoma (EC) cell lines. Previously, we determined that EC cell-specific transcriptional activation of the FGF-4 gene depends on a synergistic interaction between octamer-binding proteins and an EC-specific factor, Fx, that bind adjacent sites on the FGF-4 enhancer. Through the cloning and characterization of an F9 cell cDNA we now show that the latter activity is Sox2, a member of the Sry-related Sox factors family. Sox2 can form a ternary complex with either the ubiquitous Oct-1 or the embryonic-specific Oct-3 protein on FGF-4 enhancer DNA sequences. However, only the Sox2/Oct-3 complex is able to promote transcriptional activation. These findings identify FGF-4 as the first known embryonic target gene for Oct-3 and for any of the Sox factors, and offer insights into the mechanisms of selective gene activation by Sox and octamer-binding proteins during embryogenesis.

Distribution of acidic fibroblast growth factor mRNA-expressing neurons in the adult mouse central nervous system

The distribution of acidic fibroblast growth factor (aFGF) mRNA-expressing neurons was studied throughout the adult mouse central nervous system (CNS) with in situ hybridization histochemistry using a radiolabelled synthetic oligodeoxynucleotide probe complementary to the mRNA of human aFGF. We report here a widespread distribution of aFGF mRNA in several defined functional systems of the adult mouse brain, whereby the highest levels of aFGF mRNA were found in large somatomotor neurons in the nuclei of the oculomotor, trochlear, abducens, and hypoglossal nerves; in the motoneurons of the ventral spinal cord and the special visceromotor neurons in the motor nucleus of the trigeminal nerve; and in the facial and ambiguus nuclei. Labelled perikarya were also detected in all central structures of the auditory pathway including the level of the inferior colliculus, i.e., the lateral and medial superior nuclei; the trapezoid, cochlear, and lateral lemniscal nuclei; and parts of the anterior colliculus. Furthermore, many aFGF-positive cell bodies were found in the vestibular system and other structures projecting to the cerebellum, in the deep cerebellar nuclei, in somatosensory structures of the medulla (i.e., in the gracile, cuneate, and external cuneate nuclei), as well as in the spinal nucleus of the trigeminal nerve. The findings that aFGF mRNA is expressed in all components of several well-defined systems (i.e., in sensory structures) as well as in central neurons that process sensory information and, finally, in some efferent projections point towards a concept of aFGF expression primarily within certain neuronal circuitries.

Effective prevention of thrombocytopenia in mice using adenovirus-mediated transfer of HST-1 (FGF-4) gene

HST-1 (FGF-4) gene product is a member of the fibroblast growth factor family with a signal peptide and plays a crucial role in limb development. We showed previously that an intraperitoneal injection of replication-deficient adenovirus containing the HST-1 gene (Adex1HST-1) into normal mice caused a twofold increase in peripheral platelet count. To investigate whether Adex1HST-1 could effectively prevent experimentally induced thrombocytopenia in mice, we injected Adex1HST-1 intraperitoneally into thrombocytopenic mice induced by administration of a chemotherapeutic agent and/or by irradiation. A single Adex1HST-1 injection caused continuously increased levels of serum HST-1 protein for at least 30 d and increased the count of large megakaryocytes in bone marrow, which specifically recovered platelet counts and more efficiently diminished the extent and duration of thrombocytopenia than any other reported cytokine or any combination of cytokines so far. In the other peripheral hematological parameters, no discernible differences were detected. No other apparent side effects were observed. Therefore, this method could be useful for treatment and/or prevention of thrombocytopenia induced by chemotherapy and/or irradiation for cancer treatment.

Quantitative export of FGF-2 occurs through an alternative, energy-dependent, non-ER/Golgi pathway

Although basic fibroblast growth factor (bFGF/FGF-2) is found outside cells, it lacks a conventional signal peptide sequence; the mechanism underlying its export from cells is therefore unknown. Using a transient COS-1 cell expression system, we have identified a novel membrane-associated transport pathway that mediates export of FGF-2. This export pathway is specific for the 18-kD isoform of FGF-2, is resistant to the anti-Golgi effects of Brefeldin A, and is energy-dependent. In FGF-2-transfected COS-1 cells, this ER/Golgi-independent pathway appears to be constitutively active and functions to quantitatively export metabolically-labeled 18-kD FGF-2. Co-transfection and co-immunoprecipitation experiments, using a vector encoding the cytoplasmic protein neomycin phosphotransferase, further demonstrated the selectivity of this export pathway for FGF-2. When neomycin phosphotransferase was appended to the COOH-terminus of 18-kD FGF-2, the chimera was exported. However, the transmembrane anchor sequence of the integral membrane glycoprotein (G protein) of vesicular stomatitis virus (VSV) blocked export. The chimeric protein localized to the plasma membrane with its FGF-2 domain extracellular and remained cell-associated following alkaline carbonate extraction. Taken together, the data suggest that FGF-2 is "exported" from cells via a unique cellular pathway, which is clearly distinct from classical signal peptide-mediated secretion. This model system provides a basis for the development and testing of therapeutic agents which may block FGF-2 export. Such an intervention may be of considerable use for the treatment of angiogenesis-dependent diseases involving FGF-2.

Fibroblast growth factor receptor is required for in vivo cardiac myocyte proliferation at early embryonic stages of heart development

In birds and mammals, cardiac myocytes terminate mitotic activity in the neonatal period and regeneration of cardiac muscle does not occur after myocardial injury in adult hearts. Even embryonic myocytes, which actively proliferate in vivo, quickly lose mitotic activity when placed in cell culture. Several growth factors, including fibroblast growth factor (FGF), have been documented in embryonic hearts and some have been shown to influence myocyte terminal differentiation in culture. However, none of these growth factors have been shown to reactivate cell division in postmitotic myocytes nor have their in vivo functions been defined satisfactorily. To clarify the role of FGF signaling in heart growth, we prepared two retroviral vectors capable of suppressing (i) functions of FGF receptors (FGFRs) with a dominant-negative mutant of receptor type 1 (FGFR1) or (ii) the translation of endogenous FGFR1 by transcribing its antisense RNA. Both vectors inhibited myocyte proliferation and/or survival during the first week of chicken embryonic development but had much less effect after the second week. No apparent alteration of myocyte growth was observed after overexpression of full-length FGFR1. These results suggest that receptor-coupled FGF signaling regulates cardiac myocyte growth during tubular stages of cardiogenesis but that myocyte growth becomes FGF-independent after the second week of embryogenesis.

Requirement of FGF-4 for postimplantation mouse development

Fibroblast growth factors (FGFs) are thought to influence many processes in vertebrate development because of their diverse sites of expression and wide range of biological activities in in vitro culture systems. As a means of elucidating embryonic functions of FGF-4, gene targeting was used to generate mice harboring a disrupted Fgf4 gene. Embryos homozygous for the null allele underwent uterine implantation and induced uterine decidualization but did not develop substantially thereafter. As was consistent with their behavior in vivo, Fgf4 null embryos cultured in vitro displayed severely impaired proliferation of the inner cell mass, whereas growth and differentiation of the inner cell mass were rescued when null embryos were cultured in the presence of FGF-4 protein.

Keratinocyte growth factor as a cytokine that mediates mesenchymal-epithelial interaction

Keratinocyte growth factor (KGF) is a member of the heparin-binding fibroblast growth factor family (FGF-7) with a distinctive pattern of target-cell specificity. Studies performed in cell culture suggested that KGF was mitogenically active only on epithelial cells, though from a variety of tissues. In contrast, KGF was produced solely by cells of mesenchymal origin, leading to the hypothesis that it might function as a paracrine mediator of mesenchymal-epithelial communication. Biochemical analysis and molecular cloning established that the KGF receptor (KGFR) was a tyrosine kinase isoform encoded by the fgfr-2 gene. Many detailed investigations of KGF and KGFR expression in whole tissue and cell lines largely substantiated the pattern initially perceived in vitro of mesenchymal and epithelial distribution, respectively. Moreover, functional assays in organ culture and in vivo and analysis of agents regulating KGF expression reinforced the idea that KGF acts predominantly on epithelial cells. While the data do not implicate a KGF autocrine loop in neoplasia, paracrine sources of factor or ligand-independent signaling by the KGFR might contribute to malignancy. Alternatively, because of its differentiation-promoting effects, KGF may retard processes that culminate in uncontrolled cell growth.

Effects of oxygen on wound responses to growth factors: Kaposi's FGF, but not basic FGF stimulates repair in ischemic wounds

Kaposi's fibroblast growth factor (K-FGF, FGF-4) is a newer member of FGF family with uncharacterized wound healing properties. Basic fibroblast growth factor (bFGF, FGF-2) has been well studied and accelerates repair in normal and impaired wound healing models. K-FGF and bFGF are known to have similar biological effects in tissue culture, and both stimulate fibroblast and endothelial cell proliferation. The rabbit dermal ulcer model was used to examine the effects of bFGF and K-FGF under ischemic and nonischemic conditions. We found bFGF was ineffective in stimulating healing under ischemic conditions even at high doses (30 micrograms/wound). However, when the ischemic wounds were treated with bFGF (5 micrograms/wound) plus hyperbaric oxygen therapy, it was highly effective again as previously found under nonischemic conditions (P < 0.05). In contrast K-FGF stimulated repair in both nonischemic and ischemic wounds (P < 0.05). These results suggest that wound oxygen content differentially regulates responsiveness to bFGF and that K-FGF is biologically active in hypoxic wounds.

Adenovirus-mediated transfer of the HST-1 (FGF4) gene induces increased levels of platelet count in vivo

The HST-1 (fibroblast growth factor 4, FGF4) protein is a potent mitogen for a variety of cell types of mesodermal and neuroectodermal origin, including fibroblasts, endothelial cells, and melanocytes in vitro. To identify the cells and tissue targets of HST-1 in vivo, adenovirus-mediated HST-1 gene transfer was performed. In nude mice, intraperitoneal injection of 3 x 10(9) plaque-forming units of adenoviruses carrying the HST-1 gene (Adex1HST-1L) caused an increase in the number of platelets in the peripheral blood. The number of platelets reached twice the pretreated level by 12 days after the virus injection and the increased level continued up to 20-30 days thereafter. Administration of recombinant HST-1 protein resulted in a transient increase in the platelet count. The number of megakaryocytes in the bone marrow and spleen of the animals with Adex1HST-1L was increased compared with the control animals. Other hematological changes attributed to HST-1 were not observed. Although the mechanisms involved in increased levels of platelet count by HST-1 protein remain to be elucidated, these findings also suggest that adenovirus with the HST-1 gene may be efficiently used for the treatment of thrombocytopenia in various diseases.

Interaction between a novel F9-specific factor and octamer-binding proteins is required for cell-type-restricted activity of the fibroblast growth factor 4 enhancer

Understanding how diverse transcription patterns are achieved through common factor binding elements is a fundamental question that underlies much of developmental and cellular biology. One example is provided by the fibroblast growth factor 4 (FGF-4) gene, whose expression is restricted to specific embryonic tissues during development and to undifferentiated embryonal carcinoma cells in tissue culture. Analysis of the cis- and trans-acting elements required for the activity of the previously identified FGF-4 enhancer in F9 embryonal carcinoma cells showed that enhancer function depends on sequences that bind Sp1 and ubiquitous as well as F9-specific octamer-binding proteins. However, sequences immediately upstream of the octamer motif, which conform to a binding site for the high-mobility group (HMG) domain factor family, were also critical to enhancer function. We have identified a novel F9-specific factor, Fx, which specifically recognizes this motif. Fx formed complexes with either Oct-1 or Oct-3 in a template-dependent manner. The ability of different enhancer variants to form the Oct-Fx complexes correlated with enhancer activity, indicating that these complexes play an essential role in transcriptional activation of the FGF-4 gene. Thus, while FGF-4 enhancer function is octamer site dependent, its developmentally restricted activity is determined by the interaction of octamer-binding proteins with the tissue-specific factor Fx.

Interaction between a novel F9-specific factor and octamer-binding proteins is required for cell-type-restricted activity of the fibroblast growth factor 4 enhancer

Understanding how diverse transcription patterns are achieved through common factor binding elements is a fundamental question that underlies much of developmental and cellular biology. One example is provided by the fibroblast growth factor 4 (FGF-4) gene, whose expression is restricted to specific embryonic tissues during development and to undifferentiated embryonal carcinoma cells in tissue culture. Analysis of the cis- and trans-acting elements required for the activity of the previously identified FGF-4 enhancer in F9 embryonal carcinoma cells showed that enhancer function depends on sequences that bind Sp1 and ubiquitous as well as F9-specific octamer-binding proteins. However, sequences immediately upstream of the octamer motif, which conform to a binding site for the high-mobility group (HMG) domain factor family, were also critical to enhancer function. We have identified a novel F9-specific factor, Fx, which specifically recognizes this motif. Fx formed complexes with either Oct-1 or Oct-3 in a template-dependent manner. The ability of different enhancer variants to form the Oct-Fx complexes correlated with enhancer activity, indicating that these complexes play an essential role in transcriptional activation of the FGF-4 gene. Thus, while FGF-4 enhancer function is octamer site dependent, its developmentally restricted activity is determined by the interaction of octamer-binding proteins with the tissue-specific factor Fx.

Fibroblast growth factors in the nervous system

Fibroblast growth factors (FGFs) exhibit widespread mitogenic and neurotrophic activities. Nine members of the family are currently known, and FGF-1 and FGF-2 are present in relatively high levels in CNS. FGF-1 is expressed by a subset of neuronal populations, while FGF-2 is expressed by astrocytes. FGF-1 and FGF-2 lack signal peptides and appear to be present mainly in intracellular compartments. This suggests that the factors may act as initiators of a repair response after injury. Support for this notion comes from observations that FGF-1 and FGF-2 levels are low during critical phases of development, but high in the adult CNS. A family of transmembrane tyrosine kinase receptors (FGFRs) mediates the effects of FGFs. Four different genes coding for FGF receptors are currently known, three of which are expressed in cell type-specific patterns in the CNS. The main receptor variants present in this tissue, however, can by themselves not distinguish between FGF-1 and FGF-2. Additional selectivity may be established by interaction of the FGFs and their receptors with select heparan proteoglycans (HSPGs). Therefore, the precise physiological role of FGFs is determined by the combination of cell type-specific patterns of expression of FGFs, FGFRs and HSPGs together with the mechanisms that regulate the extracellular availability of FGFs.

Basic fibroblast growth factor and fibroblast growth factor receptor I are implicated in the growth of human astrocytomas

Malignant astrocytomas are highly invasive, vascular neoplasms that comprise the majority of nervous system tumors in humans. A strong association has previously been made between malignancy in human astrocytic tumors and increased expression of certain fibroblast growth factor (FGF) family members, including basic and acidic FGF. The influence of endogenous basic FGF on glioblastoma cell growth in vitro was evaluated using basic FGF-specific antisense oligonucleotides. These studies indicated that human glioblastoma cell growth in vitro, can be inhibited by suppressing basic FGF expression. Human astrocytomas also exhibited changes in FGF receptor (FGFR) expression during the course of their progression from a benign to a malignant phenotype. FGFR2 (bek) expression was abundant in normal white matter and in all low grade astrocytomas, but was not observed in glioblastomas. Conversely, FGFR1 (flg) expression was absent or barely detectable in normal white matter, but was significantly elevated in glioblastomas. Glioblastomas also expressed an alternatively spliced form of FGFR1 containing two immunoglobulin-like disulfide loops (FGFR1 beta), whereas normal human adult and fetal brain expressed a form of the receptor containing three immunoglobulin-like disulfide loops (FGFR1 alpha). Intermediate grades of astrocytic tumors exhibited a gradual loss of FGFR2 and a shift in expression from FGFR1 alpha to FGFR1 beta as they progressed from a benign to a malignant phenotype. The underlying cytogenetic changes that contribute to these alterations are not entirely understood, but abnormalities in the p53 tumor suppressor gene may influence expression of bFGF as well as the FGFR. These results suggest that alterations in FGFR signal transduction pathways may play a critical role in the malignant progression of astrocytic tumors.

Multivalent ligand-receptor binding interactions in the fibroblast growth factor system produce a cooperative growth factor and heparin mechanism for receptor dimerization

The binding interactions for the three primary reactants of the fibroblast growth factor (FGF) system, basic FGF (bFGF), an FGF receptor, FGFR1, and the cofactor heparin/heparan sulfate (HS), were explored by isothermal titrating calorimetry, ultracentrifugation, and molecular modeling. The binding reactions were first dissected into three binary reactions: (1) FGFR1 + bFGF<==>FGFR1/bFGF, K1 = 41 (+/- 12) nM; (2) FGFR1 + HS<==>FGFR1/HS, K2 = 104 (+/- 17) microM; and (3) bFGF + HS<==>bFGF/HS, K3 = 470 (+/- 20) nM, where HS = low MW heparin, approximately 3 kDa. The first, binding of bFGF to FGFR1 in the absence of HS, was found to be a simple binary binding reaction that is enthalpy dominated and characterized by a single equilibrium constant, K1. The conditional reactions of bFGF and FGFR1 in the presence of heparin were then examined under conditions that saturate only the bFGF heparin site (1.5 equiv of HS/bFGF) or saturate the HS binding sites of both bFGF and FGFR1 (1.0 mM HS). Both 3-and 5-kDa low MW heparins increased the affinity for FGFR1 binding to bFGF by approximately 10-fold (Kd = 4.9 +/- 2.0 nM), relative to the reaction with no HS. In addition, HS, at a minimum of 1.5 equiv/bFGF, induced a second FGFR1 molecule to bind to another lower affinity secondary site on bFGF (K4 = 1.9 +/- 0.7 microM) in an entropy-dominated reaction to yield a quaternary complex containing two FGFR1, one bFGF, and at least one HS. Molecular weight estimates by analytical ultracentrifugation of such fully bound complexes were consistent with this proposed composition. To understand these binding reactions in terms of structural components of FGFR1, a three-dimensional model of FGFR1 was constructed using segment match modeling. Electrostatic potential calculations confirmed that an elongated cluster, approximately 15 x 35 A, of nine cationic residues focused positive potential (+2kBT) to the solvent-exposed beta-sheet A, B, E, C' surface of the D(II) domain model, strongly implicating this locus as the HS binding region of FGFR1. Structural models for HS binding to FGFR1, and HS binding to bFGF, were built individually and then assembled to juxtapose adjacent binding sites for receptor and HS on bFGF, against matching proposed growth factor and HS binding sites on FGFR1. The calorimetric binding results and the molecular modeling exercises suggest that bFGF and HS participate in a concerted bridge mechanism for the dimerization of FGFR1 in vitro and presumably for mitogenic signal transduction in vivo.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of gene amplification and overexpression in human esophageal-carcinoma cell lines

Gene amplification/overexpression was analyzed in 23 cell lines derived from human esophageal squamous-cell-carcinoma tissues by Southern and Northern hybridizations to c-myc, c-erbB, hst-1 and cyclin-D1 probes. Amplification of the c-myc gene was observed in 5 cell lines derived from well-differentiated carcinomas and all of them were accompanied by co-amplification of other examined oncogenes. The c-erbB gene was amplified in 3 cell lines. Co-amplification of hst-1 and cyclin D1, both of which are located in chromosome 11q13, was found in 9 cell lines. Without exception their amplification was simultaneous and the magnitudes were similar. Their amplification, but not their overexpression, was significantly correlated with poor prognosis in patients from whom the cell lines were established. While hst-1-gene expression was not detected, at least 1 of the genes analyzed was overexpressed in 20 cell lines vs. its expression in normal esophageal mucosal tissues. However, gene amplification was not necessarily accompanied by overexpression of the corresponding genes. Expression of the cyclin D1 gene, which has been assumed to be a target gene for 11q13 amplification, was not detected in one particular cell line with amplification of 11q13. These results suggest that the amplification/overexpression of more than I oncogene is involved in the carcinogenic process of esophageal carcinoma and that c-myc-gene amplification is associated with a well-differentiated subtype. There remains a possibility that key oncogenes other than cyclin D1 are involved in 11q13 amplification.

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.