Schwannoma-derived Growth Factor Research Articles

AREG (amphiregulin (schwannoma-derived growth factor))

Review on AREG (amphiregulin (schwannoma-derived growth factor)), with data on DNA, on the protein encoded, and where the gene is implicated.

IGFBP-rP1, a potential molecule associated with colon cancer differentiation

BackgroundIn our previous studies, we have demonstrated that insulin-like growth factor binding protein-related protein1 (IGFBP-rP1) played its potential tumor suppressor role in colon cancer cells through apoptosis and senescence induction. In this study, we will further uncover the role of IGFBP-rP1 in colon cancer differentiation and a possible mechanism by revealing responsible genes.ResultsIn normal colon epithelium, immunohistochemistry staining detected a gradient IGFBP-rP1 expression along the axis of the crypt. IGFBP-rP1 strongly expressed in the differentiated cells at the surface of the colon epithelium, while weakly expressed at the crypt base. In colon cancer tissues, the expression of IGFBP-rP1 correlated positively with the differentiation status. IGFBP-rP1 strongly expressed in low grade colorectal carcinoma and weakly expressed in high grade colorectal carcinoma. In vitro, transfection of PcDNA3.1(IGFBP-rP1) into RKO, SW620 and CW2 cells induced a more pronounced anterior-posterior polarity morphology, accompanied by upregulation with alkaline phosphatase (AKP) activity. Upregulation of carcino-embryonic antigen (CEA) was also observed in SW620 and CW2 transfectants. The addition of IGFBP-rP1 protein into the medium could mimic most but not all effects of IGFBP-rP1 cDNA transfection. Seventy-eight reproducibly differentially expressed genes were detected in PcDNA3.1(IGFBP-rP1)-RKO transfectants, using Affymetrix 133 plus 2.0 expression chip platform. Directed Acyclic Graph (DAG) of the enriched GO categories demonstrated that differential expression of the enzyme regulator activity genes together with cytoskeleton and actin binding genes were significant. IGFBP-rP1 could upreguate Transgelin (TAGLN), downregulate SRY (sex determining region Y)-box 9(campomelic dysplasia, autosomal sex-reversal) (SOX9), insulin receptor substrate 1(IRS1), cyclin-dependent kinase inhibitor 2B (p15, inhibits CDK4) (CDKN2B), amphiregulin(schwannoma-derived growth factor) (AREG) and immediate early response 5-like(IER5L) in RKO, SW620 and CW2 colon cancer cells, verified by Real time Reverse Transcription Polymerase Chain Reaction (rtRT-PCR). During sodium butyrate-induced Caco2 cell differentiation, IGFBP-rP1 was upregulated and the expression showed significant correlation with the AKP activity. The downregulation of IRS1 and SOX9 were also induced by sodium butyrate.ConclusionIGFBP-rP1 was a potential key molecule associated with colon cancer differentiation. Downregulation of IRS1 and SOX9 may the possible key downstream genes involved in the process.

Biological actions of the epidermal growth factors-like domain peptides of mouse schwannoma-derived growth factor and human amphiregulin.

Several members of the epidermal growth factor (EGF) family of growth factors that contain EGF-like units at their carboxy portion have been isolated and characterized. Schwannoma-derived growth factor (SDGF) and amphiregulin (AR) are members of this family. SDGF has high sequence homology to AR, and is known to be not only a potent mitogen for astrocytes and fibroblasts but also a neurotrophic factor. We previously confirmed that the synthetic EGF-like peptides SDGF(38-80) and AR(44-84), corresponding to the EGF-like domain of mouse SDGF and human AR, respectively, formed similar disulfide bond patterns to that of EGF. In the present study, we further investigated the biological actions of these two EGF-like peptides on several cultured cell lines. We found that SDGF(38-80) and AR(44-84) have weak mitogenic activity in NIH/3T3 cells and weak binding affinity to the EGF receptor on the surface of A431 cells compared with EGF. However, SDGF(38-80) and EGF induced short neurite outgrowth in PC12 h cells, a subclone of PC12 cells, at 100 nM. In addition, a significant increase in acetylcholinesterase (AChE) activity induced by SDGF(38-80) was observed at a concentration similar range to that of EGF, which is known as a differentiation marker of these cells. The effect of AR(44-84) in PC12 h cells was weaker than those of SDGF(38-80) and EGF, but the AChE activity was significantly increased by the addition of 100 nM AR(44-84), which did not stimulate NIH/3T3 cell growth. These results also suggest that SDGF(38-80) and AR(44-84) may be effective for neuronal differentiation rather than proliferation.

Heparin-binding epidermal growth factor-like growth factor stimulates mitogenic signaling and is highly expressed in human malignant gliomas.

We previously reported that schwannoma-derived growth factor (SDGF), a member of heparin-binding epidermal growth factor (EGF) family, participates in autocrine pathways and promotes rat glioma cell growth. To investigate the potential role of similar molecules in human gliomas, we examined 7 human glioma cell lines and 11 glioblastoma specimens for expression of the human homologue of SDGF, amphiregulin (AR), as well as heparin-binding EGF-like growth factor (HB-EGF). Northern blot analysis revealed that only one cell line and no tumor specimens expressed AR mRNA. In contrast, HB-EGF mRNA was expressed in all human glioma cell lines and its level of expression was two- to five-fold higher than that of control brain tissues in 8 of 11 glioblastoma cases. Immunohistochemistry demonstrated that membrane-anchored HB-EGF (proHB-EGF) and EGFR were co-expressed in 44% of 34 human malignant gliomas. Introduction of exogenous HB-EGF (10 ng/ml) increased human glioma cell proliferation, and anti-HB-EGF blocking antibodies reduced the growth of glioma cells by 30-40%, confirming the presence of an autocrine loop. When added to the medium, transforming growth factor-alpha, basic fibroblast growth factor, or HB-EGF rapidly induced HB-EGF mRNA expression. These results indicate that HB-EGF and proHB-EGF contribute to the growth of human malignant glioma cells, most likely through autocrine and juxtacrine mechanisms.

Specific Inhibition of Hair Follicle Formation by Epidermal Growth Factor in an Organ Culture of Developing Mouse Skin

Embryonic mouse skin undergoes a drastic morphological change from 13 to 16 gestational days, i.e., formation of rudiments of hair follicles and stratification and cornification of interfollicular epidermis. To investigate underlying molecular mechanisms of the morphogenesis, we established an organ culture system that allows skin tissues isolated from 12.5- or 13.5-days postcoitus embryos to develop in a manner that is histologically and temporally similar to the processin vivo.Expression of differentiation markers of epidermal keratinocytes including cholesterol sulfotransferase and cytokeratin K1 was induced in culture, as it occurs alsoin vivo.The morphogenic process was observed by time-lapse videomicrography. In this culture system, epidermal growth factor (EGF) and transforming growth factor α specifically and completely inhibited the hair follicle formation with marginal effects on interfollicular epidermis. The inhibitory action by EGF was reversible and stage specific, i.e., at an early stage of the development of hair rudiments. Among known ligands to the EGF receptor, Schwannoma-derived growth factor and heparin-binding EGF were expressed inin vivoepidermis during the period of the initial formation of hair follicles. EGF receptor is expressed in epidermis throughout the developing period examined. Using an adenovirus vector, we demonstrated that the lacZ gene was transduced into the epidermal and dermal cell layers without appreciable toxicity. These results indicate that the present culture system provides a unique opportunity to investigate molecular mechanisms of skin morphogenesis including the role of EGF signaling under defined experimental conditions.

Increased expression of Schwannoma-derived growth factor (SDGF) mRNA in rat tumor cells: Involvement of SDGF in the growth promotion of rat gliomas

Schwannoma-derived growth factor (SDGF) is a member of the epidermal growth factor (EGF) family, having mitogenic activity on rat astrocytes, fibroblasts and Schwann cells. The SDGF gene is significantly expressed in the newborn rat lung and in the adult rat sciatic nerve. However, except for one rat schwannoma cell line, from which SDGF and its cDNA were isolated, nothing is known about SDGF expression in established tumor cell lines. We examined the expression level of the SDGF gene in a variety of rat tumor cell lines by Northern blotting and found that it was increased in 11 of 25 established lines. The most abundant SDGF mRNA, which was about 50-fold higher than in the newborn rat lung, was expressed in rat liver adenoma dRLa74 cells. In rat glioma cell lines, such as C6, 9L and T9, and in the rat hepatoma dRLh84 and H411E cells, the SDGF expression level was about 10-fold higher than in the newborn rat lung. In 8 of 13 cell lines expressing SDGF mRNA, the EGF receptor (EGFR) gene, the product of which is regarded as a functional receptor of SDGF, was co-expressed. In addition, transfected gene-dependent anti-sense SDGF RNA expression under the control of the human metallothionein promoter significantly suppressed the in vitro growth as well as in vivo tumorigenicity of 9L glioma cells. Our results suggest that SDGF acts as an autocrine growth factor in the development and growth of rat tumors such as gliomas.

Chemical synthesis and biological activities of the EGF‐like domain of mouse schwannoma‐derived growth factor (SDGF)

Schwannoma-derived growth factor (SDGF), an epidermal growth factor (EGF) family peptide recently discovered, has an EGF-like domain in the carboxyl terminal portion. In this study, we synthesized mSDGF(38-80) corresponding to the EGF-like domain of mouse SDGF by means of stepwise solid-phase method using Fmoc chemistry in order to evaluate the biological function of the EGF-like domain in SDGF. The linear peptide of mSDGF(38-80) was folded by direct oxidation with reduced and oxidized glutathione to form intramolecular disulfide bridges in synthetic peptide. On the biological activity, we examined mitogenic activity induced by mSDGF(38-80) in NIH/3T3 fibroblast cells and interaction with EGF receptor in A431 cells. In the results, mSDGF(38-80) was confirmed to form three disulfide linkages that were similar in pattern to EGF by amino acid and sequence analysis of fragments obtained after thermolytic digestion. However, mSDGF(38-80) possessed weak mitogenic activity in NIH/3T3 cells and weak binding affinity for the EGF receptor in A431 cells compared with those of human EGF. These results suggest that the EGF-like domain of SDGF may have little effect upon mitogenic activity and the EGF receptor binding of SDGF.

Schwannoma-derived growth factor interacts with the epidermal growth factor receptor.

Schwannoma-derived growth factor (SDGF) is a potent mitogen and neuronal differentiation factor. Because of its relationship to epidermal growth factor (EGF) and the heregulins, it was asked if SDGF interacts with the EGF receptor or HER2/neu. SDGF binds to and causes the phosphorylation on tyrosine of the EGF receptor but not HER2/neu.

Nuclear/growth factors

The now classical model for cell-cell communication espouses that information travels between cells in the form of molecules that bind specific cell-surface receptors and trigger signal-transducing mechanisms that eventually lead to transcriptional modifications. Here we gather the available information suggesting that some growth factors may also act by interfering directly with gene transcription, following their internalization and nuclear translocation. Among these factors are bona fide growth factors such as Fibroblast Growth Factor-1 and -2 and Schwannoma Derived Growth Factor, for which internalization and nuclear translocation have been demonstrated. Conversely, we propose that some isoforms of nuclear factors of the homeoprotein family could pass from cell to cell. The implications of the model are presented in the context of the specificity of cellular interactions.

Internalization of macromolecules by live cells

The membrane of eukaryotic cells represents a barrier normally impermeable to non-lipophilic substances. In consequence, internalization of extracellular compounds requires the presence of specific channels, or of specialized endocytic mechanisms. Recently, several groups have reported that some growth factors and transcription factors can be internalized by cells in culture and addressed to the cytoplasmic and nuclear compartments. In the latter case, they have been shown to interfere directly with gene transcription. Among these factors are fibroblast growth factor-1 and -2 (FGF-1 and FGF-2), schwannoma-derived growth factor (SDGF), Tat protein and homeodomain or homeodomain containing polypeptides. In the present paper, we present the available data concerning these unconventional uptake mechanisms and speculate on their potential interest to target macromolec-ular structures into live cells.

Schwannoma-derived growth factor must be transported into the nucleus to exert its mitogenic activity.

Schwannoma-derived growth factor (SDGF) is a mitogen and neurotrophic protein which belongs to the epidermal growth factor (EGF) family. There are two basic amino acid clusters in the SDGF molecule which are homologous to the nuclear targeting signal of the simian virus 40-encoded large tumor antigen. Mutational analysis of these clusters showed that they function as nuclear targeting signals, and a gel retardation assay showed that SDGF binds to A+T-rich DNA sequences. Both the wild-type SDGF and a mutant defective in the nuclear targeting signals activate the immediate early genes NGFI-A and c-fos. The wild-type SDGF is a mitogen for Swiss mouse 3T3 fibroblasts, but the mutant defective in the nuclear targeting signals is not mitogenic. Moreover, wild-type SDGF potentiates [3H]thymidine incorporation in NIH mouse 3T3 cells bearing an EGF receptor defective in the kinase domain, whereas the mutant SDGF does not stimulate DNA synthesis. These results suggest that transport into the nucleus is required for SDGF to induce a mitogenic response.

Androgen-responsive expression and mitogenic activity of schwannoma-derived growth factor on an androgen-dependent Shionogi mouse mammary carcinoma cell line

We report here, using the androgen-dependent SC2G cell line derived from Shionogi mouse mammary carcinoma SC115, that cDNA encoding mouse homologue of the rat schwannoma-derived growth factor (SDGF) was isolated and its protein product was identified to be an autocrine growth factor which is expressed in response to androgen in this hormone-dependent cell line. The androgen-independent SC1G cells derived from SC115 were shown to express SDGF even in the absence of androgen, while Northern analysis probed with mouse mammary tumor virus (MMTV) DNA showed that the androgen inducible transcriptional machinery remains functional in this hormone independent cell line.

Schwannoma-derived growth factor promotes the neuronal differentiation and survival of PC12 cells.

Schwannoma-derived growth factor (SDGF) was initially isolated from schwannoma cells as a mitogen for glial cells and fibroblasts. The present data show that SDGF causes the morphological and molecular differentiation of rat PC12 cells in a manner similar to, but distinguishable from nerve growth factor (NGF). It also promotes PC12 survival in serum-free conditions. SDGF induced changes include neurite outgrowth and the induction of the mRNAs for GAP-43 and transin, proteins which are highly expressed in axons. In addition, both SDGF and NGF induce the transcription factor, NGFI-A. The time course of the response to SDGF is similar to that for NGF. Gap-43 mRNA induction by both SDGF and NGF is inhibited by dexamethasone, but dexamethasone has no effect on NGFI-A mRNA synthesis. These observations show that SDGF has a differentiation and survival promoting effect on PC12 cells in addition to its mitogenic activity on glial cells and fibroblasts.

Structure, expression and function of a schwannoma-derived growth factor

During the development of the nervous system, cells require growth factors that regulate their division and survival. To identify new growth factors, serum-free growth-conditioned media from many clonal cell lines were screened for the presence of mitogens for central nervous system glial cells. A cell line secreting a potent glial mitogen was established from a tumour (or 'schwannoma') derived from the sheath of the sciatic nerve. The cells of the tumour, named JS1 cells, were adapted to clonal culture and identified as Schwann cells. Schwann cells secrete an autocrine mitogen and human schwannoma extracts have mitogenic activity on glial cells. Until now, neither mitogen has been purified. Here we report the purification and characterization of a mitogenic molecule, designated schwannoma-derived growth factor (SDGF), from the growth-conditioned medium of the JS1 Schwann cell line. SDGF belongs to the epidermal growth factor family, and is an autocrine growth factor as well as a mitogen for astrocytes, Schwann cells and fibroblasts.