Human endothelial cell growth factor: cloning, nucleotide sequence, and chromosome localization

Isolation of heparin-binding growth factors from bovine, porcine and canine hearts

Fresh bovine, porcine and canine hearts were homogenized and mitogens for mesoderm-derived cells were purified in three different steps. Extraction by two different ammonium sulfate precipitations was followed by cation-exchange chromatography and by heparin-Sepharose affinity chromatography. A heparin-Sepharose fraction from heart (eluted at 1.1 M NaCl) increased mitotic activity in serum-deprived cultures of porcine aortic endothelial and smooth muscle cells, and in human fibroblasts. This mitogenic activity is potentiated by heparin and inhibited by gamma-interferon. The heart mitogenic fraction showed one double peak on HPLC at A215 and one polypeptide band on SDS/PAGE. These peaks and bands were identical to those obtained from bovine brain. The heart acidic fibroblast growth factor (aFGF) showed a positive signal in Western blots using antibodies raised against brain aFGF. Gas-phase amino acid sequencing established that the mitogens were identical to aFGF and the N-terminally truncated aFGF. Extraction in the presence of a protease inhibitor (pepstatin A) produced a higher-molecular mass form of aFGF with a blocked amino terminus. Another mitogen, eluted at 1.6 M NaCl from heparin-Sepharose, reacted with polyclonal antiserum against human recombinant basic fibroblast growth factor (bFGF) and showed a 66% (12 from 18 amino acids determined by gas-phase sequencing) similarity with bFGF. This polypeptide increased the mitotic activity of the same cell lines but was more potent than aFGF.

Identification of angiogenic activity and the cloning and expression of platelet-derived endothelial cell growth factor

Cloning and sequencing of the complementary DNA for platelet-derived endothelial cell growth factor indicates that it is a novel factor distinct from previously characterized proteins. The factor, a protein with a relative molecular mass of about 45,000, stimulates endothelial cell growth and chemotaxis in vitro and angiogenesis in vivo.

Growth factor expression in aorta of normotensive and hypertensive rats

Hypertension causes biochemical and morphological changes in the vessel wall by unknown mechanisms. Locally produced substances may have a role in mediating these vascular changes. We have studied the expression of platelet-derived growth factor (PDGF) B chain and PDGF A chain, insulin-like growth factor (IGF)-I and IGF-II, endothelial cell growth factor (ECGF), basic fibroblast growth factor (bFGF), and transforming growth factor-beta (TGF-beta) in aortic tissue from normotensive rats and rats made hypertensive by deoxycorticosterone (DOC)/salt treatment. Using Northern blotting, we found that genes for each of these growth factors were transcriptionally active in the aorta of both normotensive and hypertensive rats. TGF-beta aortic mRNA levels increased up to threefold as a result of DOC/salt hypertension. In contrast, no major changes in the expression of either PDGF chain, IGF-I or II, ECGF, or bFGF were detectable. The results indicate that at least seven genes coding for growth factors that were shown previously to influence growth and function of vascular cells in vitro, are expressed in rat aorta in vivo. These findings support the hypothesis that synthesis and release of growth factors in the arterial wall are involved in autocrine and/or paracrine regulatory mechanisms. In addition, the increased expression of TGF-beta in vivo may have a role in mediating the aortic changes induced by hypertension.

Acidic fibroblast growth factor mRNA is expressed by cardiac myocytes in culture and the protein is localized to the extracellular matrix

Acidic and basic fibroblast growth factors are heparin-binding proteins that induce cellular proliferation, mesodermal development, and vascular growth. As such, they may be important in cardiac development and disease. To determine whether cardiac myocytes contain fibroblast growth factors, neonatal rat cardiac myocytes were studied in primary culture and compared to primary cultures of nonmyocyte cardiac cells. Northern blot analysis revealed a 4.0-kilobase mRNA in myocytes that hybridized to acidic fibroblast growth factor cDNA and was not detectable in nonmyocyte cultures. Western blot analysis demonstrated the accumulation of a 15-kDa peptide with immunological identity to acidic fibroblast growth factor in extracts of extracellular matrix from myocyte cultures that was not detectable in similar extracts of nonmyocyte extracellular matrix. No acidic fibroblast growth factor-like protein was detectable in cellular lysates from either myocyte or nonmyocyte cultures. These results demonstrate that neonatal cardiac myocytes express acidic fibroblast growth factor mRNA and deposit a protein with immunological identity to acidic fibroblast growth factor into the extracellular matrix. The results suggest that acidic fibroblast growth factor produced by cardiac myocytes may mediate, through both paracrine and autocrine mechanisms, such diverse processes as myocyte differentiation, cellular proliferation, and vascular growth in the heart.

Growth of normal human keratinocytes and fibroblasts in serum-free medium is stimulated by acidic and basic fibroblast growth factor

Keratinocytes and fibroblasts isolated from human neonatal foreskin can be plated and grown through multiple rounds of division in vitro under defined serum-free conditions. We utilized these growth conditions to examine the mitogenic potential of acidic and basic fibroblast growth factor (aFGF and bFGF) on these cells. Our results demonstrate that both aFGF and bFGF can stimulate the proliferation of keratinocytes and fibroblasts. aFGF is a more potent mitogen than bFGF for keratinocytes. In contrast, bFGF appears to be more potent than aFGF in stimulating the growth of fibroblast cultures. Heparin sulfate (10 micrograms/ml) dramatically inhibited the ability of bFGF to stimulate the proliferation of keratinocytes. In comparison, heparin slightly inhibited the stimulatory effect of aFGF and had no effect on epidermal growth factor (EGF) stimulation in keratinocyte cultures. In fibroblast cultures the addition of heparin enhanced the mitogenic effect of aFGF, had a minimal stimulatory effect on the mitogenic activity of bFGF, and had no effect on EGF-stimulated growth. Our results demonstrate that the proliferation in vitro of two normal cell types found in the skin can be influenced by aFGF and bFGF and demonstrate cell-type specific differences in the responsiveness of fibroblasts and keratinocytes to these growth factors and heparin.

The human FGF-5 oncogene encodes a novel protein related to fibroblast growth factors

We previously described the isolation of a human oncogene which had acquired transforming potential by a DNA rearrangement accompanying transfection of NIH 3T3 cells with human tumor DNA (X. Zhan, A. Culpepper, M. Reddy, J. Loveless, and M. Goldfarb, Oncogene 1:369-376, 1987). We now term this oncogene the FGF-5 gene, since it specifies the fifth documented protein related to fibroblast growth factors (FGFs. Two regions of the FGF-5 sequence, containing 122 of its 267 amino acid residues, were 40 to 50% homologous to the sequences of acidic and basic FGFs as well as to the sequences of the FGF-related oncoproteins int-2 and hst/KS3. The FGF-5 gene bears the three exon structures typical for members of this family. FGF-5 was found to be expressed in the neonatal brain and in 3 of the 13 human tumor cell lines examined. Several experiments strongly suggested that FGF-5 is a growth factor with properties common to those of acidic and basic FGFs. The rearrangement which activated the FGF-5 gene during DNA transfection had juxtaposed a retrovirus transcriptional enhancer just upstream from the native promoter of the gene.

The sequence of human parathymosin deduced from a cloned human kidney cDNA

The amino acid sequence of human parathymosin has been deduced from the cDNA sequence of a clone isolated from a human kidney cDNA library. Screening of the cDNA library with a probe containing a partial rat cDNA sequence yielded two clones containing inserts of 1200 and 1100 base pairs respectively, each including the complete open reading frame for human parathymosin. The open reading frame contains 306 nucleotides, including the codon for the initiator methionine. Analysis of the 5' flanking sequence excluded the presence of a hydrophobic signal peptide in the translated sequence. It may therefore be concluded that parathymosin, like prothymosin alpha, is synthesized without formation of a large precursor polypeptide. Comparison of the deduced amino acid sequence with the known primary structure of rat and bovine parathymosins shows that the primary structure of parathymosin is highly conserved among these species.

Prothymosin alpha and parathymosin: mRNA and polypeptide levels in rodent tissues

Blot hybridization analyses have established the presence of mRNAs for prothymosin alpha (ProT alpha) and for parathymosin (ParaT) in rat and mouse lung, liver, kidney, and brain, confirming the biosynthesis of these peptides in nonlymphoid tissues. In these tissues the levels of mRNAs paralleled the content of the polypeptides, determined with specific radioimmunoassays. The mRNA levels also confirmed the reciprocal relation between the two polypeptides; ProT alpha and its mRNA were found in highest concentrations in spleen and thymus, followed by lung, kidney, and brain, with lowest concentrations in liver. On the other hand, liver contained highest concentrations of ParaT and the mRNA for ParaT, with lowest levels present in spleen and thymus. In comparison to tissues from young (6-8 week) mice, older (18 month) mice contained lower concentrations (20-40%) of both polypeptides, with qualitatively similar decreases in mRNA content.

Induction of interleukin-1 receptors on chondrocytes by fibroblast growth factor: a possible mechanism for modulation of interleukin-1 activity

Interleukin-1 is a polypeptide factor with profound effects on several cell types, such as chondrocytes, fibroblasts, and T-cells. The ability of interleukin-1 to induce the synthesis of matrix-degradative enzymes, as well as prostaglandin E2, suggests a pivotal role for this mediator in chronic inflammation. Previous studies have shown that the effect of human monocyte interleukin-1 on the synthesis of collagenase and neutral proteases by chondrocytes was enhanced by basic fibroblast growth factor. Using recombinant human interleukin-1B, we have examined whether the potentiation of interleukin-1 effects by fibroblast growth factor is related to changes in the number or affinity of interleukin-1 receptors. Our studies confirm that rabbit articular chondrocytes in culture contain a single class of high-affinity receptors for interleukin-1 with a Ka of 0.9-1.1 x 10(-13) M-1. While the untreated chondrocytes contain approximately 1,620 receptors per cell, fibroblast growth factor-treated cells exhibit a higher number of receptors (approximately 2,960 per cell) with no apparent change in the affinity. The increase in receptor number can be abolished by inhibitors of lysosomal function, indicating a requirement for intracellular processing of the fibroblast growth factor. Our results suggest that the potentiation of interleukin-1 catabolic effects by fibroblast growth factor may be related to its ability to induce additional interleukin-1 receptors on the chondrocyte cell surface.

AIDS-Kaposi's sarcoma-derived cells express cytokines with autocrine and paracrine growth effects

When grown in vitro, cells from Kaposi's sarcoma lesions of AIDS patients (AIDS-KS cells) constitutively release several growth promoting activities. When inoculated into nude mice, the AIDS-KS cells induce a KS-like lesion of mouse origin. Here it is shown that the AIDS-KS cells express messenger RNA for a complex mixture of cytokines that correlate with several of the biological activities of these cells. Basic fibroblast growth factor, which is a potent angiogenic factor, and interleukin-1 messenger RNAs are expressed at very high levels and seem to account for a large proportion of the activities, since their corresponding proteins are released in biologically active form into the culture media where they induce autocrine and paracrine growth effects.

Role of colony-stimulating factors in the biology of acute myelogenous leukemia

A high proportion of acute myeloid leukemias (AML) recently investigated for their capacity to synthesize biologically active bioregulatory molecules was found to accumulate messenger (m) RNA and to produce membrane-bound or -secreted forms of stimulating factors for granulocyte, macrophage and mixed granulocyte-macrophage colony growth. Blast cells have also been found to secrete interleukin 1, tumor necrosis factor-alpha, interleukin 6, and to express receptors for various growth factors as well. However, growth factors like interleukin 2 and interleukin 3 have not been identified as AML products, and several other factors including interleukin 4, interleukin 5, etc. need further evaluation. Responsiveness of clonogenic leukemic cells to exogenous growth-promoting factors in vitro suggests a possible role of these biomolecules in the course of these disorders. Important evidence for the crucial role of growth factors, at least in some subtypes of AML, has been provided by demonstrating constitutive growth factor production by leukemic cells and their autonomous in vitro growth which is dependent on autocrine secretion of a specific growth factor. The concert of mechanisms providing stimulatory and inhibitory signals for hematopoiesis, which is adapted to the various physiological requirements of the organism, may have multiple defects in AML. This leads to successive steps of malfunctioning of cells, which finally express a fully malignant phenotype. In addition, these derangements also lead to defects in accessory cells on the level of mediator communication. However, there is evidence for autonomous growth promotion of AML blast by constitutive production of growth factors active in an autocrine fashion (GM-CSF, G-CSF, interleukin 6) and by recruitment of accessory cells to increase CSF supply (GM-CSF, G-CSF) via molecules such as interleukin 1 and TNF-alpha in a paracrine fashion. Molecular analysis of transformed hematopoietic cells has revealed changes of the genome, e.g., insertion of viral genetic information or cytogenetic fractures at DNA sites controlling growth factor gene activation. These events appear to be crucial in the induction of uncontrolled growth factor expression promoting oncogenic transformation of hematopoietic progenitor cells.

Localization of basic fibroblast growth factor to the developing capillaries of the bovine retina

The basic fibroblast growth factor (FGF) is a potent mitogen that has vascular endothelium as one of its principle target cells. Recent work has provided both the complete amino acid sequence of basic FGF and the nucleotide sequence of the genes for both human and bovine basic FGF. Although capillary endothelial cells have been shown to produce basic FGF in vitro and to deposit basic FGF in their extracellular matrix in vitro as well, no direct evidence yet exists for the distribution of basic FGF in vivo. Antipeptide antibodies were prepared against a 15-amino-acid sequence from the amino terminus of basic FGF in order to avoid cross-reactivity with acidic FGF, a protein with 55% overall homology to basic FGF. After affinity purification, these antisera were used to localize the basic fibroblast growth factor in the fetal and adult bovine retina. Immunoreactive material was found in capillaries of the inner nuclear layer, a capillary network undergoing development during the third trimester in the fetal bovine eye. Although the resolution of the technique does not permit a unique assignment of cellular localization, the presence of stain immediately adjacent to the lumen of capillaries suggests that capillary endothelial cells may produce the basic fibroblast growth factor in vivo during vascular development.

The structure and function of the int-2 oncogene

The classification of int-2 as a growth factor is based primarily on the similarities between the predicted amino acid sequence and that of basic fibroblast growth factor (bFGF), as well as other members of this expanding family of related proteins. In this review, we summarise the background to the identification of int-2 as a proto-oncogene in virally induced mouse mammary tumours and describe key features of the structure and expression of both the mouse and human homologues. The normal sites of int-2 expression include specific embryonic cell types suggesting multiple inductive or morphogenetic roles. Recent progress in the characterisation of the int-2 product will be discussed in relation to the similarities and differences between int-2 and other FGFs.

High affinity binding sites for basic fibroblast growth factor in rat hepatic plasma membranes

The binding of [125I]-recombinant basic FGF (rec bFGF) to rat hepatic plasma membranes was investigated. [125I] rec bFGF bound to an apparent single class of high affinity binding sites (KD = 69 pM; Bmax = 9.61 fmoles/mg proteins). The absence of low affinity sites was confirmed by the inability of sulphated polysaccharides and heparinase to interfere with FGF binding. A good correlation existed between the ability of bovine pituitary-derived bFGF, rec bFGF and bovine brain-derived aFGF to displace [125I]rec bFGF from these binding sites and their in vitro potency on bovine aortic endothelial cell proliferation.

An endothelial cell growth factor from the mouse neuroblastoma cell line NB41

A growth factor that stimulates the proliferation of endothelial cells from human umbilical vein but is not mitogenic for fibroblastic cells is present in medium conditioned by the mouse neuroblastoma cell line NB41. In a partially purified preparation, factor activity coeluted from a reverse-phase high-pressure liquid chromatography (HPLC) column with a reduced protein of about 24 kd. Activity recovered following electrophoresis of HPLC fractions corresponded to protein of 43-51 kd in the absence of reducing agent and to protein of 23-29 kd after reduction. Antiserum raised against a peptide corresponding to the putative N-terminal amino acid sequence of the 24-kd protein reacted with the 24-kd protein and with a protein of about 47 kd in the nonreduced preparation. After N-glycanase treatment, the immunoreactive 24-kd protein had a mobility corresponding to 19 kd. We infer that the native NB41 factor is a glycosylated dimer whose biochemical and biological properties distinguish if from other endothelial cell growth factors.

The fibroblast growth factor family: structural and biological properties

This article summarizes the structural and biological properties of the family of fibroblast growth factors (FGF). Basic FGF (bFGF) and acidic FGF (aFGF) are the best characterized members of this family. bFGF and aFGF are potent modulators of cell proliferation, motility and differentiation. They are also potent angiogenesis factors in vivo. Some of the important biological characteristics of bFGF and aFGF discussed in the review include the affinity of bFGF and aFGF for heparin, their lack of secretion in culture and their association with extracellular matrix. Recently, several oncogenes, 40-50% homologous in sequence to bFGF and aFGF have been identified. These include int-2, hst, K-fgf and FGF-5. The structural and biological properties of these FGF-related oncogenes are also discussed.

Fibroblast growth factor and the control of pituitary and gonad development and function

Evidence from in vitro studies support the concept that growth factors could be involved in the development, maturation and function of endocrine organs. Included among the growth factors which are known to influence endocrine cell proliferation and differentiation is the fibroblast growth factor (FGF), which controls the proliferation, differentiation, and other functions of mesodermal- and neuroectodermal-derived cells. Its modulator, transforming growth factor beta (TGF beta), which determines the positive or negative direction of the effects of FGF, may play a role as well. In this review, we present a speculative view of how FGF in the pituitary gland, and both FGF and TGF beta in the gonads could influence the development and function of these organs through regulating mechanisms involving paracrine and autocrine control of cell proliferation and differentiation.

Human hemopoietic growth factors

Hematopoiesis is regulated by a complex network of soluble stimulators and inhibitors, as well as by cellular interactions in the bone marrow microenvironment. Progress in molecular biology and protein biochemistry has provided a number of hemopoietic growth factors that are now available in large quantities for in vitro and in vivo studies. Several of them seem to hold great promise for patients suffering from insufficient hematopoiesis of various causes. This review focuses on new developments in the understanding of hemopoietic growth factors activity, and on recent clinical data.

Effects of acidic and basic fibroblast growth factors on osteoblastic cells

Acidic (a) and basic (b) fibroblast growth factors (FGFs) are two related mitogenic and angiogenic factors. They are multifunctional in that they can affect proliferation and induce or delay differentiation. Both aFGF and bFGF were shown to stimulate proliferation of calvaria cells in situ as well as osteoblast-enriched calvaria-derived cells. bFGF was also found to suppress the expression of alkaline phosphatase, parathyroid hormone stimulatable adenylate cyclase, osteocalcin, and type I collagen in the osteoblastic ROS 17/2.8 cells. To explore a possible role for guanine nucleotide binding proteins we assessed the effects of pertussis toxin (PT) on FGF action. PT had opposite effects to those of bFGF on all parameters examined.

Characterization of a bovine acidic FGF cDNA clone and its expression in brain and retina

A cDNA encoding the acidic eye-derived growth factor (EDGF II) similar to the acidic fibroblast growth factor (aFGF), a potent cell mitogen, has been isolated from a bovine retinal cDNA library. The cDNA, 4.1 kb in size, has a sequence coding for the 155 amino acids of bovine aFGF, and shows similarity with human aFGF (87% identity). The coding sequence is flanked by a 5'-untranslated region of 0.8 kb and a 3'-untranslated end of 3.0 kb. Northern blot analysis of bovine brain and retina poly(A+) RNAs showed the existence of four aFGF mRNA species. Two of these species are 9.9 and 6.0 kb in size, not abundant and could represent premessengers. The other two species, 4.2 and 2.5 kb, are abundant.

Two homologous oncogenes, HST1 and INT2, are closely located in human genome

Pulsed field gel electrophoresis and Southern blot analysis showed that the human oncogenes, HST1 and INT2, which code for proteins homologous to fibroblast growth factors, are less than 45 kb apart on the long arm of chromosome 11. Moreover, analysis of two overlapping cosmid clones, one containing INT2 and the other HST1 sequences, showed that HST1 is located about 35 kb downstream of INT2 in the same transcriptional orientation. The observed close proximity of the INT2 and HST1 genes may provide important insight on the origin and regulation of expression of these related genes.

Fibroblast (heparin-binding) growing factors in neuronal development and repair

Nearly thirty growth and trophic factors that have been purified from mammalian tissues in the last 15 yr have been found to share chemical identity. The results of their chemical purification and molecular cloning show that they are two distinct polypeptides (Mr 17,400 and 18,400), each of which gives rise to families of smaller size peptides. These peptides share a common affinity for heparin. In view of this property, a common nomenclature for the two principle peptide growth factors (heparin-binding growth factor classes 1 and 2; HBGF-1 and -2) has been proposed. However, the names acidic and basic Fibroblast Growth Factors (aFGF,bFGF), which were applied to them originally to describe their mitogenic activity, are more commonly in use and will therefore be adopted in this review. Brain tissue is one of the richest sources of FGFs. It has been used as a starting point for their chemical purification and to prepare genomic libraries for molecular cloning of the aFGF and bFGF genes. There is increasing evidence that these growth factors, expressed in neurons and glia throughout the mammalian nervous system, are implicated in neuronal cell proliferation, differentiation, and histogenesis. FGFs have a strong affinity not only for heparin, but also for the related heparan sulphate proteoglycans that are abundant in neural tissues. This fact provides a clue to the importance of tissue-associated proteoglycans in mediating the release, sequestration, and activation of FGFs and the modulation of their receptor binding and bioactivity. The relevance of FGFs to neural development and their mechanisms of action in neurons will be considered in light of the existing literature describing their biological properties and activity in mesodermal cell types. Evidence is reviewed showing that FGFs have in vivo biological activity, ameliorating the degeneration of central and peripheral neurons after axotomy. The presence and implications of high levels of FGFs in adult mammalian brain provides a direction for future research into neural regeneration. The bioactivity of FGFs in neural tissue may not depend on the regulation of their expression per se, but on the subregional modification of their interaction with proteoglycans.

Production of growth factors related to fibroblast growth factor and platelet-derived growth factor by human embryonal carcinoma cells

Previous studies have demonstrated that mouse embryonal carcinoma (EC) cells produce at least two growth factors: one related to platelet-derived growth factor (PDGF) and another related to basic fibroblast growth factor (FGFb). Since human EC cell lines are being used with increased frequency, the current study examined whether human EC cells produce growth factors, in particular those produced by mouse EC cells. In this study, it was determined that the human EC cell line NT2/D1 produces a heat-labile heparin-binding growth factor that behaves like FGF in a bioassay. Three additional criteria suggest that this factor is closely related or identical to FGFb. The factor from NT2/D1 EC cells, bovine FGFb and FGFb produced by the human hepatoma cell line SK-HEP-1 elute from heparin at similar salt concentrations. The factor produced by NT2/D1 EC cells exhibits a thermal stability curve that is nearly identical to those for bovine FGFb and FGFb from SK-HEP-1 cells. Lastly, NT2/D1 and SK-HEP-1 cells express transcripts of the same size that hybridize with a cDNA probe for human FGFb. In the course of these studies it was determined that NT2/D1 EC cells also express several transcripts that hybridize with a cDNA probe for the human PDGF A-chain. Thus, our findings suggest that the pattern of growth factor production by human and mouse EC cells is evolutionarily conserved.

Tandem linkage of human CSF-1 receptor (c-fms) and PDGF receptor genes

A 5' untranslated exon of the human CSF-1 receptor gene (c-fms) is separated by a 26 kb intron from the 32 kb receptor coding sequences. Nucleotide sequence analysis of cloned genomic DNA revealed that the 3' end of the PDGF receptor gene is located less than 0.5 kb upstream from this exon. Similarities in chromosomal localization, organization, and encoded amino acid sequences suggest that the genes encoding the CSF-1 and PDGF receptors arose through duplication. The as yet unidentified c-fms promoter/enhancer sequences may be confined to the nucleotides separating the two genes or could potentially lie within the PDGF receptor gene itself.

Acidic fibroblast growth factor stimulates adrenal chromaffin cells to proliferate and to extend neurites, but is not a long-term survival factor

Acidic fibroblast growth factor (aFGF) is a heparin-binding polypeptide that is a mitogen for endothelial cells and glial cells, as well as a differentiation factor for PC12 cells and certain neurons. We show here that aFGF is as potent as nerve growth factor (NGF) in stimulating both neuritic outgrowth and proliferation in adrenal chromaffin cells from young rats, but it fails to support long-term survival. Heparin strongly potentiates aFGF-dependent neuritic outgrowth but not aFGF-dependent proliferation. As is the case with NGF, phorbol myristate acetate depresses aFGF-induced cell division and increases the outgrowth of neurites. On the other hand, dexamethasone antagonizes neuritic outgrowth elicited by both NGF and aFGF but inhibits only proliferation induced by NGF. The effects of basic FGF (bFGF) are similar but not identical to those of aFGF. Thus the regulatory pathways controlled by aFGF, bFGF, and NGF are partially distinct.

Kaposi's sarcoma cells: long-term culture with growth factor from retrovirus-infected CD4+ T cells

Studies of the biology and pathogenesis of Kaposi's sarcoma (KS) have been hampered by the inability to maintain long-term cultures of KS cells in vitro. In this study AIDS-KS-derived cells with characteristic spindle-like morphology were cultured with a growth factor (or factors) released by CD4+ T lymphocytes infected with human T-lymphotropic virus type I or II (HTLV-I or HTLV-II) or with human immunodeficiency virus type 1 or 2 (HIV-1 or HIV-2). Medium conditioned by HTLV-II-infected, transformed lines of T cells (HTLV-II CM) contained large amounts of this growth activity and also supported the temporary growth of normal vascular endothelial cells, but not fibroblasts. Interleukin-1 and tumor necrosis factor-alpha stimulated the growth of the KS-derived cells, but the growth was only transient and these could be distinguished from that in HTLV-II CM. Other known endothelial cell growth promoting factors, such as acidic and basic fibroblast growth factors and epidermal growth factor, did not support the long-term growth of the AIDS-KS cells. The factor released by CD4+ T cells infected with human retroviruses should prove useful in studies of the pathogenesis of KS.

Increased basic fibroblast growth factor (bFGF) immunoreactivity at the site of focal brain wounds

Basic fibroblast growth factor (bFGF) is a polypeptide found within the CNS with potent effects on the survival and proliferation of CNS glia and endothelial cells, and on the survival and outgrowth of CNS neurons. Immunohistochemical methods were used to examine relative changes in the levels and distribution of bFGF following focal brain injury. Two monospecific antisera to bFGF were used to immunostain intact mature rat brain, and brain in which a focal mechanical lesion had been made in the dorsolateral cerebral cortex one week previously. In the intact brain, staining was localized primarily in neuronal cell bodies, especially in limbic structures. In injured brain, a marked increase of bFGF immunoreactivity was found at the borders of lesions, localized to the dense accumulation of cells, many of which resembled 'reactive' astroglia. Such increases in local bFGF concentrations may contribute to the cascade of cellular changes--including glial and capillary proliferation, and neural sprouting--that follows focal brain injury.

Site-directed neovessel formation in vivo

Angiogenesis is an important component of organogenesis and wound repair and occurs during the pathology of oncogenesis, atherogenesis, and other disease processes. Thus, it is important to understand the physiological mechanisms that control neovascularization, especially with methods that permit the molecular dissection of the phenomenon in vivo. Heparin-binding growth factor-1 was shown to bind to collagen type I and type IV. When complexed with gelatin, heparin-binding growth factor-1 can induce neovascularization at polypeptide concentrations that are consistent with the biological activity of the mitogen in vitro. The adsorption strategy induces rapid blood vessel formation at and between organ- and tissue-specific sites and permits recovery of the site-specific implant for examination and manipulation by molecular methods.

Production and utilization of growth factors related to fibroblast growth factor by embryonal carcinoma cells and their differentiated cells

Previous studies have established that embryonal carcinoma (EC) cells produce several different growth factors, but express few, if any, receptors for epidermal growth factor, platelet-derived growth factor, or transforming growth factor type-beta. In this study, the production and utilization of fibroblast growth factor (FGF) by EC cells and their differentiated cells were investigated. We have determined that EC cells produce a heat-labile, heparin-binding factor that competes with FGF for binding to membrane receptors and appears to be immunologically related to FGF. The same or a similar factor is produced by three different EC cell lines, including a multipotent human EC cell line. However, production of this factor is apparently reduced when each EC cell line differentiates. Unlike the parental EC cells, the differentiated cells respond to FGF by growth stimulation and the growth responses to FGF correlate with increased binding of FGF. Although the binding data indicate that both the EC cells and their differentiated cells exhibit high affinity receptors for FGF, the differentiated cells express these receptors at levels approximately 10-fold higher. These findings suggest that the FGF-related growth factor could influence the growth of EC cells or their differentiated cells.

Growth control of A431 cells in protein-free medium: secretory products do not affect cell growth

A431 cells grew at similar rates in protein-free Coon's modified Ham's F12 medium (PF-C-F12) with and without added bovine calf serum. The cells secreted a heparin-binding growth factor and a type-beta transforming growth factor, but their growth in PF-C-F12 was not affected by these factors, or by DNA synthesis factor from Rhodamine fibrosarcoma, basic fibroblast growth factor, insulin, human transferrin, bovine serum albumin, and their combinations. Growth of A431 cells in PF-C-F12 was not density dependent and was not affected by either addition of conditioned medium or replacement of conditioned medium by fresh medium. These results indicate that A431 cells have an intracellular mechanism for autonomous growth, and that their growth is not affected by factors that they secrete or by exogenous growth factors.

Differential expression of mRNA coding for heparin-binding growth factor type 2 in human cells

The proliferation of normal human fibroblasts, keratinocytes, and melanocytes in vitro can be controlled by purified polypeptide growth factors and serum. We have studied the cellular expression of the heparin-binding growth factor type 2/basic fibroblast growth factor (HBGF-2/bFGF) gene to determine whether these cell types synthesize mRNA for this mitogen. Our results indicate that normal human fibroblasts synthesize four distinct mRNAs of 7.0, 3.7, 2.2, and 1.5 kilobases, which hybridize to a specific HBGF-2/bFGF cDNA probe. In fibroblasts, the level of all four of these transcripts increases dramatically (more than tenfold) within 4 hours of treatment of quiescent cells with fresh fetal bovine serum. Of the purified growth factors tested, transforming growth factor type-beta also increased HBGF-2/bFGF mRNA abundance, but not to the levels attained by serum treatment. Treatment of fibroblasts with cycloheximide before and during serum treatment blocked the ability of serum to induce the expression of the HBGF-2/bFGF gene. The gene is expressed at low levels in human fibroblasts rapidly growing in serum-free medium and at higher levels in cells rapidly growing in serum-containing medium. In contrast to fibroblasts, mRNA coding for HBGF-2/bFGF is undetectable in proliferating normal human keratinocytes, melanocytes, or mammary epithelial cells. Because keratinocytes and melanocytes proliferate in response to purified HBGF-2/bFGF, our results suggest that HBGF-2/bFGF may mediate the proliferation of epidermal cells through paracrine mechanisms involving stromal fibroblasts. Moreover, we have shown that a human squamous cell carcinoma cell line (SCC-25) expresses mRNA coding for HBGF-2/bFGF, suggesting that the gene may become activated in some carcinomas.

The human FGF-5 oncogene encodes a novel protein related to fibroblast growth factors

We previously described the isolation of a human oncogene which had acquired transforming potential by a DNA rearrangement accompanying transfection of NIH 3T3 cells with human tumor DNA (X. Zhan, A. Culpepper, M. Reddy, J. Loveless, and M. Goldfarb, Oncogene 1:369-376, 1987). We now term this oncogene the FGF-5 gene, since it specifies the fifth documented protein related to fibroblast growth factors (FGFs. Two regions of the FGF-5 sequence, containing 122 of its 267 amino acid residues, were 40 to 50% homologous to the sequences of acidic and basic FGFs as well as to the sequences of the FGF-related oncoproteins int-2 and hst/KS3. The FGF-5 gene bears the three exon structures typical for members of this family. FGF-5 was found to be expressed in the neonatal brain and in 3 of the 13 human tumor cell lines examined. Several experiments strongly suggested that FGF-5 is a growth factor with properties common to those of acidic and basic FGFs. The rearrangement which activated the FGF-5 gene during DNA transfection had juxtaposed a retrovirus transcriptional enhancer just upstream from the native promoter of the gene.

Elevation of acidic fibroblast growth factor mRNA in lesioned rat brain

A 40-base oligodeoxynucleotide probe is described which has been prepared corresponding to the amino acid sequence 9-22 of acidic fibroblast growth factor. Following electrophoretic separation of rat brain mRNA under denaturing conditions the probe hybridizes to a major polyadenylated mRNA species of approximately 4.8 kb. This mRNA is the same size as that reported for acidic fibroblast growth factor mRNA. The relative abundance of the hybridizing 4.8 kb mRNA species increases in rat brain 3 days after cortical lesion indicating increased expression of the gene for acidic fibroblast growth factor.

Clinical applications of heparin-binding growth factors

The family of HBGFs represents one of the most important families of mediators yet described, capable of inducing mesenchymal cell proliferation and differentiation, tissue regeneration, morphogenesis, and neovascularization, and it is clear their clinical potential is enormous. While some obvious applications of HBGFs, such as in wound healing and seeding of vascular prostheses, are already being examined in detail, the realization of their full clinical potential will require the co-ordinated efforts of many laboratories in a wide spectrum of fields. A better understanding is needed of the pathophysiological roles of HBGFs in vivo. For example, if abnormal expression of HBGFs is the cause of certain pathologies characterized by abnormal vascularization, the clinical potential of HBGF antagonists as inhibitors of angiogenesis will be considerable. A better understanding is also needed of the relationship between HBGF structure and function, susceptibility to proteolysis, in-vivo stability, and synergism with other biological response modifiers. In addition, many clinical applications will be limited by our ability to target HBGFs to selected sites in the body, while others will be limited by undesirable side-effects. Indeed, the minimization of such side-effects may rapidly become a central issue in the in-vivo use of HBGFs. For example, the presence of HBGFs in ocular tissues, their role in phototransduction, their ability to induce neovascularization, and the clear link between abnormal ocular neovascularization and blindness, suggest that the eye may be an organ particularly sensitive to local changes in HBGF levels. Finally, HBGFs will almost certainly have extremely potent immunoregulatory effects. Nevertheless, the application of HBGFs in a variety of clinical situations should lead to many innovative therapeutic advances.

Human HST1 (HSTF1) gene maps to chromosome band 11q13 and coamplifies with the INT2 gene in human cancer

The human HST1 gene, previously designated the hst gene, and now assigned the name HSTF1 for heparin-binding secretory transforming factor in human gene nomenclature, was originally identified as a transforming gene in DNAs from human stomach cancers by transfection assay with mouse NIH 3T3 cells. The amino acid sequence of the product deduced from DNA sequences of the HST1 cDNA and genomic clones had approximately 40% homology to human basic and acidic fibroblast growth factors and mouse Int-2-encoded protein. We have mapped the human HST1 gene to chromosome 11 at band q13.3 by Southern blot hybridization analysis of a panel of human and mouse somatic cell hybrids and in situ hybridization with an HST1 cDNA probe. The HST1 gene was found to be amplified in DNAs obtained from a stomach cancer and a vulvar carcinoma cell line, A431. In all of these samples of DNA, the INT2 gene, previously mapped to human chromosome 11q13, was also amplified to the same degree as the HST1 gene.

Inversion of chromosome 5 long arm in region of cell growth gene cluster in hematologic disorders

Inversions of the long (q) arm of chromosome #5 are reported in five cases with hematologic disorders. Inversion of 5q with breakpoints in bands 5q13 and 5q33 was found in two cases with lymphoid malignancy and in two cases of myeloid hematologic malignancy. Because an inversion of 5q with breakpoints in 5q22 and 5q33 was also found in a case with myeloproliferative syndrome, the common denominator in these five cases was band 5q33. An extraordinary cluster of genes affecting cell growth and differentiation is present on 5q and may be altered by the chromosome rearrangement of 5q in hematologic disorders.

Endothelial cell-astrocyte interactions. A cellular model of the blood-brain barrier

Microvascular endothelial cells in the brain have a number of special properties that underlie formation of the blood-brain barrier (BBB) and contribute to control of the neuronal microenvironment. Evidence from transplantation experiments indicates that signals arising within brain rather than a programmed commitment of the endothelial cells are responsible for the expression of blood-brain barrier properties. The close anatomic relationship between brain endothelial cells and the foot processes of astrocytes suggests a role for astrocytes as a source of the differentiation signals. It is now possible to isolate and separately culture populations of brain-derived endothelial cells and astrocytes. When the two cell types are grown together, a characteristic morphologic organization occurs that is associated with induction of enzymes and tight junctions similar to those found in vivo. Endothelial cells and astrocytes in culture differ in their production of and response to specific polypeptide growth factors. These findings provide the basis for a model of endothelial cell-astrocyte interaction that may explain several aspects of BBB behavior.

Chromosomal localization of the human interleukin 1 alpha (IL-1 alpha) gene

The human interleukin 1 alpha gene was assigned to chromosome 2 using Southern transfer analysis of human-rodent somatic cell hybrid DNAs. The gene was regionally localized to 2q12-21 using in situ hybridization to metaphase chromosomes. These results indicate that the IL-1 alpha gene maps to the same general region on the long arm of chromosome 2 as the IL-1 beta gene, which has been previously assigned.