Transforming growth factor-beta 2: cDNA cloning and sequence analysis

TGFβ1 protein trap AVID200 beneficially affects hematopoiesis and bone marrow fibrosis in myelofibrosis

Myelofibrosis (MF) is a progressive chronic myeloproliferative neoplasm characterized by hyperactivation of JAK/STAT signaling and dysregulation of the transcription factor GATA1 in megakaryocytes (MKs). TGF-β plays a pivotal role in the pathobiology of MF by promoting BM fibrosis and collagen deposition and by enhancing the dormancy of normal hematopoietic stem cells (HSCs). In this study, we show that MF-MKs elaborated significantly greater levels of TGF-β1 than TGF-β2 and TGF-β3 to a varying degree, and we evaluated the ability of AVID200, a potent TGF-β1/TGF-β3 protein trap, to block the excessive TGF-β signaling. Treatment of human mesenchymal stromal cells with AVID200 significantly reduced their proliferation, decreased phosphorylation of SMAD2, and interfered with the ability of TGF-β1 to induce collagen expression. Moreover, treatment of MF mononuclear cells with AVID200 led to increased numbers of progenitor cells (PCs) with WT JAK2 rather than mutated JAK2V617F. This effect of AVID200 on MF PCs was attributed to its ability to block TGF-β1–induced p57^Kip2 expression and SMAD2 activation, thereby allowing normal rather than MF PCs to preferentially proliferate and form hematopoietic colonies. To assess the in vivo effects of AVID200, Gata1^lo mice, a murine model of MF, were treated with AVID200, resulting in the reduction in BM fibrosis and an increase in BM cellularity. AVID200 treatment also increased the frequency and numbers of murine progenitor cells as well as short-term and long-term HSCs. Collectively, these data provide the rationale for TGF-β1 blockade, with AVID200 as a therapeutic strategy for patients with MF.

Absence of Expression of c-sis and Transforming Growth Factor-β mRNA in Malignant Fibrous Histiocytoma

Total RNA was extracted from five malignant fibrous histiocytomas and two benign fibrohistiocytic lesions and assayed for mRNA expressions for transforming growth factor beta (TGF-β) and c-sis by Northern blot analysis. Production of both of these has been associated with cells of monocyte-macrophage lineage, and these factors have been shown to be important in physiologic mesenchymal cell proliferation. No mRNA expression of either TGF-β or c-sis was identified in any of the fibrohistiocytic tumor samples. The lack of expression of TGF-β and c-sis may be consistent with a nonhistiocytic origin of malignant fibrous histiocytoma, or may reflect transformation- associated loss of the normal molecular mechanisms of mesenchymal proliferation. The absence of c-sis mRNA expression can be reconciled with the prior immunohisto chemical demonstration of platelet-derived growth factor in tumor cells of malignant fibrous histiocytoma. Int J Surg Pathol(2):117-122, 1993

Development and characterization of human monoclonal antibodies that neutralize multiple TGFβ isoforms

Transforming growth factor (TGF)β levels are elevated in, and drive the progression of, numerous disease states such as advanced metastatic cancer and systemic and ocular fibrosis. There are 3 main isoforms, TGFβ1, 2, and 3. As multiple TGFβ isoforms are involved in disease processes, maximal therapeutic efficacy may require neutralization of 2 or more of the TGFβ isoforms. Fully human antibody phage display libraries were used to discover a number of antibodies that bind and neutralize various combinations of TGFβ1, 2 or 3. The primary panning did not yield any uniformly potent pan-isoform neutralizing antibodies; therefore, an antibody that displayed potent TGFβ 1, 2 inhibition, but more modest affinity versus TGFβ3, was affinity matured by shuffling with a light chain sub-library and further screening. This process yielded a high affinity pan-isoform neutralizing clone. Antibodies were analyzed and compared by binding affinity, as well as receptor and epitope competition by surface plasmon resonance methods. The antibodies were also shown to neutralize TGFβ effects in vitro in 3 assays: 1) interleukin (IL)-4 induced HT-2 cell proliferation; 2) TGFβ-mediated IL-11 release by A549 cells; and 3) decreasing SMAD2 phosphorylation in Detroit 562 cells. The antibodies’ potency in these in vitro assays correlated well with their isoform-specific affinities. Furthermore, the ability of the affinity-matured clone to decrease tumor burden in a Detroit 562 xenograft study was superior to that of the parent clone. This affinity-matured antibody acts as a very potent inhibitor of all 3 main isoforms of TGFβ and may have utility for therapeutic intervention in human disease.

Tgf-β1 expression as a biomarker of poor prognosis in prostate cancer

OBJECTIVE

To evaluate the correlation between transforming growth factor beta (TGF-β1) expression and prognosis in prostate cancer.

PATIENTS AND METHODS

TGF-β1 expression levels were analyzed using the quantitative real-time polymerase chain reaction to amplify RNA that had been isolated from fresh-frozen malignant and benign tissue specimens collected from 89 patients who had clinically localized prostate cancer and had been treated with radical prostatectomy. The control group consisted of li patients with benign prostate hyperplasia. The expression levels of TGF-β1 were compared between the groups in terms of Gleason scores, pathological staging, and prostate-specific antigen serum levels.

RESULTS

In the majority of the tumor samples, TGF-β1 was underexpressed 67.0% of PCa patients. The same expression pattern was identified in benign tissues of patients with prostate cancer. Although most cases exhibited underexpression of TGF-β1, a higher expression level was found in patients with Gleason scores ≥ 7 when compared to patients with Gleason scores < 7(p = 0.002). Among the 26 cases of TGF-β1 overexpression, 92.3% had poor prognostic features.

CONCLUSIONS

TGF-β1 was underexpressed in prostate cancers; however, higher expression was observed in tumors with higher Gleason scores, which suggests that TGF-β1 expression may be a useful prognostic marker for prostate cancer. Further studies of clinical specimens are needed to clarify the role of TGF-β1 in prostate carcinogenesis.

Tgf-β1 expression as a biomarker of poor prognosis in prostate cancer

OBJECTIVE

To evaluate the correlation between transforming growth factor beta (TGF-β1) expression and prognosis in prostate cancer.

PATIENTS AND METHODS

TGF-β1 expression levels were analyzed using the quantitative real-time polymerase chain reaction to amplify RNA that had been isolated from fresh-frozen malignant and benign tissue specimens collected from 89 patients who had clinically localized prostate cancer and had been treated with radical prostatectomy. The control group consisted of li patients with benign prostate hyperplasia. The expression levels of TGF-β1 were compared between the groups in terms of Gleason scores, pathological staging, and prostate-specific antigen serum levels.

RESULTS

In the majority of the tumor samples, TGF-β1 was underexpressed 67.0% of PCa patients. The same expression pattern was identified in benign tissues of patients with prostate cancer. Although most cases exhibited underexpression of TGF-β1, a higher expression level was found in patients with Gleason scores ≥ 7 when compared to patients with Gleason scores < 7(p = 0.002). Among the 26 cases of TGF-β1 overexpression, 92.3% had poor prognostic features.

CONCLUSIONS

TGF-β1 was underexpressed in prostate cancers; however, higher expression was observed in tumors with higher Gleason scores, which suggests that TGF-β1 expression may be a useful prognostic marker for prostate cancer. Further studies of clinical specimens are needed to clarify the role of TGF-β1 in prostate carcinogenesis.

Distribution of mRNAs encoding transforming growth factors-beta1, -2, and -3 in the intact rat brain and after experimentally induced focal ischemia

Transforming growth factors-beta1 (TGF-beta1), -2, and -3 form a small group of related proteins involved in the regulation of proliferation, differentiation, and survival of various cell types. Recently, TGF-betas were also demonstrated to be neuroprotective. In the present study, we investigated their distribution in the rat brain as well as their expression following middle cerebral artery occlusion. Probes were produced for all types of TGF-betas, and in situ hybridization was performed. We demonstrated high TGF-beta1 expression in cerebral cortex, hippocampus, central amygdaloid nucleus, medial preoptic area, hypothalamic paraventricular nucleus, substantia nigra, brainstem reticular formation and motoneurons, and area postrema. In contrast, TGF-beta2 was abundantly expressed in deep cortical layers, dentate gyrus, midline thalamic nuclei, posterior hypothalamic area and mamillary body, superior olive, areas of monoaminergic neurons, spinal trigeminal nucleus, dorsal vagal complex, cerebellum, and choroid plexus, and a high level of TGF-beta3 mRNA was found in cerebral cortex, hippocampus, basal amygdaloid nuclei, lateral septal nucleus, several thalamic nuclei, arcuate and supramamillary nuclei, superior colliculus, superior olive, brainstem reticular formation and motoneurons, area postrema, and inferior olive. Focal brain ischemia induced TGF-betas with markedly different expression patterns. TGF-beta1 was induced in the penumbral region of cortex and striatum, whereas TGF-beta2 and -beta3 were induced in different layers of the ipsilateral cortex. The expression of the subtypes of TGF-betas in different brain regions suggests that they are involved in the regulation of different neurons and bind to different latent TGF-beta binding proteins. Furthermore, they might have subtype-specific functions following ischemic attack.

Action, localization and structure-function relationship of growth factors and their receptors in the prostate

Whereas the direct action of sex steroids, namely of androgens, on prostate cell division was questioned as early as in the 1970s, and remains so, the interest in prostatic growth factors (GFs) is rather recent but has expanded tremendously in the last five years. This lag period can be partly explained by the fact that, at the time, androgen receptors had just been discovered, and newly developed hormonal regimens or strategies to treat patients with prostate carcinoma (PCa) or epithelioma had generated great enthusiasm and hopes in the medical and scientific community. Another point to consider was the difficulty in maintaining prostate tissues in organ cultures and the relative novelty of culturing prostate epithelial cells in monolayers. Failures of sex steroids to elicit a direct positive response on prostate cell divisionin vitro, as seenin vivo, were interpreted as resulting from inappropriate models or culture conditions. However, the increasing number of reports confirming the lack of mitogenic activity of sex steroidsin vitro, coupled with the powerful mitogenic activity of GFs displayed in other systems, the discovery of GF receptors (GF-Rs), and the elucidation of their signalling pathways showing sex steroid receptors as potential substrates of GF-activated protein kinases gradually led to an increased interest in the putative role of GFs in prostate physiopathology. Of utmost importance was the recognition that hormone refractiveness was responsible for PCa progression, and for the poor outcome of patients with advanced disease under endocrine therapies. This problem remains a major issue and it raises several key questions that need to be solved at the fundamental and clinical levels.

Relative Quantitation of Protein–Protein Interaction Strength Within the Yeast Two-Hybrid System via Fluorescenceβ-Galactosidase Activity Detection in a High-Throughput and Low-Cost Manner

The yeast two-hybrid (Y2H) method is capable of delivering vast amounts of interacting positive yeast colonies from a single library screen, particularly if a multifunctional protein is used as bait. However, the selection of definitive colonies for further molecular analysis is limited by both technical practicality and high costs. Here we demonstrate a cost-effective and simple method for the rapid selection and ranking of those Y2H-positive interaction clones that are suitable for further analysis. We performed a Y2H screen for the identification of human transforming growth factor beta2- interacting proteins in a human skin keratinocyte library. The identified clones were ranked by the amount of beta-galactosidase enzyme produced, as well as by the interaction strength of the positive colonies. The combination of high-throughput microplate fluorescence readers and specific fluorescence assays can be utilized for relative quantitation of protein-protein interaction strength of Y2H-positive colonies in crude yeast-cell lysates. We demonstrate here that the high sensitivity of the fluorescence approach can bypass cumbersome conventional methods of cell lysis used in beta-galactosidase assays, and still deliver accurate values for analysis of protein interaction data. Finally, we also achieved a better understanding of general aspects of beta-galactosidase measurements in the Y2H system, such as protein normalization, the influence of yeast culture incubation time on optimal beta-galactosidase detection, and the linearity of beta-galactosidase detection in crude cell lysates.

Genetic effects of anorganic bovine bone (Bio-Oss®) on osteoblast-like MG63 cells

Bio-Oss (Geistlich, Wolhusen, Switzerland) is composed by anorganic bovine bone and is widely used in several bone regeneration procedures in oral surgery. How this biomaterial alters osteoblast gene expression to promote bone formation is poorly understood. We therefore attempted to address this question by using microarray techniques to identify genes that are differentially regulated in osteoblasts exposed to Bio-Oss. By using DNA microarrays containing 20,000 genes, we identified in osteoblast-like cells line (MG-63) cultured with Bio-Oss several genes which expression was significantly up- and down-regulated. The differentially expressed genes cover a broad range of functional activities: (a) signaling transduction, (b) transcription, (c) cell cycle regulation, (d) vesicular transport, (e) apoptosis, and (f) immunity. These results could explain the reported bioaffinity of Bio-Oss to host animals, its biological affinity to osteogenic cells and its capability to stimulate osteoblastic differentiation. The data reported are, to our knowledge, the first genetic portrait of Bio-Oss effects. They can be relevant to our improved understanding of the molecular mechanism underlying bone regenerative procedures and as a model for comparing other materials with similar clinical effects.

The role of Smad signaling in hematopoiesis

The TGF-beta family of ligands, including TGF-beta, bone morphogenetic protein (BMP) and activin, signal through Smad pathways to regulate the fate of hematopoietic progenitor and stem cells during development and postnatally. BMP regulates hematopoietic stem cell (HSC) specification during development, while TGF-beta1, 2 and 3 are not essential for the generation of HSCs. BMP4 can increase proliferation of human hematopoietic progenitors, while TGF-beta acts as a negative regulator of hematopoietic progenitor and stem cells in vitro. In contrast, TGF-beta signaling deficiency in vivo does not affect proliferation of HSCs and does not affect lineage choice either. Therefore, the outcome of Smad signaling is very context dependent in hematopoiesis and regulation of hematopoietic stem and progenitor cells is more complicated in the bone marrow microenvironment in vivo than is seen in liquid cultures ex vivo. Smad signaling regulates hematopoiesis by crosstalk with other regulatory signals and future research will define in more detail how the various pathways interact and how the knowledge obtained can be used to develop advanced cell therapies.

TGF-beta induces Foxp3 + T-regulatory cells from CD4 + CD25 - precursors

CD4 + CD25 + regulatory T cells (Tregs) are potent suppressors, playing important roles in autoimmunity and transplantation tolerance. Understanding the signals necessary for the generation and expansion of Tregs is important for clinical cellular therapy, but only limited progress has been made. Recent reports suggest a role for TGF-beta in the generation of Tregs from CD4 + CD25 - precursors, but the mechanism remains unknown. Here, we demonstrate that TGF-beta2 triggers Foxp3 expression in CD4 + CD25 - precursors, and these Foxp3 + cells act like conventional Tregs. The generation of Foxp3 + Tregs requires stimulation of the T-cell receptor, the IL-2R and the TGF-beta receptor. More importantly, strong costimulation through CD28 prevents Foxp3 expression and suppressive function in an IL-4-dependent manner. Furthermore, TGF-beta-driven Tregs inhibit innate inflammatory responses to syngeneic transplanted pancreatic islets and enhance islet transplant survival. Thus, TGF-beta is a key regulator of the signaling pathways that initiate and maintain Foxp3 expression and suppressive function in CD4 + CD25 - precursors. TGF-beta and signaling through TGF-beta receptor, CD28 costimulation and IL-4 may be key components for the manipulation of Treg. The de novo generation of Foxp3 + cells from CD4 + cells has the potential to be used for treatment of autoimmune diseases and induction of transplant tolerance.

Cytokines in juvenile dermatomyositis pathophysiology: potential and challenge

PURPOSE OF REVIEW

Cytokines are criticalmediators of the immune response. This review focuses on cytokine-specific information from children with juvenile dermatomyositis, and includes pertinent data from adults with polymyositis and dermatomyositis.

RECENT FINDINGS

Much of the new data concern the role of possible antigens and the definition of genetic control of the immune response in juvenile dermatomyositis. Gene expression profile data of DQA1*0501 (present in 85% of patients) compared with age-matched control subjects show that the initial immune response is an interferon-alpha/beta-induced cascade with secondary stimulation of interferon-gamma. Specific epitopes of group A beta-hemolytic streptococcal M protein, with sequence homology for myosin, elicit both cell-mediated cytotoxicity and tumor necrosis factor-alpha production when incubated with mononuclear cells from children with active juvenile dermatomyositis. Tumor necrosis factor-alpha synthesis is increased in juvenile dermatomyositis patients with the tumor necrosis factor-alpha-308A allele, and is associated with increased thrombospondin-1 (an antiangiogenic agent) production and small vessel occlusion in untreated juvenile dermatomyositis. Studies in adults with polymyositis and dermatomyositis implicate interleukin-1alpha, transforming growth factor-beta, and endothelial cell perturbation early in the disease course. Cultured myoblasts were found to produce interleukin-15, which impacts local T-cell activation and proliferation.

SUMMARY

The limited data suggest that a possible viral/microbial antigen may elicit an interferon-alpha/beta-induced response, and that antigenic epitopes may be shared. Increased synthesis of tumor necrosis factor-alpha, more common in juvenile dermatomyositis with the tumor necrosis factor-alpha-308A polymorphism, may augment this response and is associated with a wide range of pathologic consequences, as well as disease chronicity and calcifications. The muscle fibers themselves can regulate local inflammation by production of tumor necrosis factor-alpha, interleukin-15 and interleukin-1alpha, and transforming growth factor-beta.

TGF-betas and their roles in the regulation of neuron survival

Transforming growth factor-betas (TGF-betas) are a still growing superfamily of cytokines with widespread distribution and diverse biological functions. They fall into several subfamilies including the TGF-betas 1, 2, and 3, the bone morphogenetic proteins (BMPs), the growth/differentiation factors (GDFs), activins and inhibins, and the members of the glial cell line-derived neurotrophic factor family. Following a brief description of their general roles and signaling in development, maintenance of homeostasis, and disease, we shall focus on their distribution in the CNS and their involvement in regulating neuron survival and death.

In vitro chondrogenesis of human bone marrow-derived mesenchymal progenitor cells in monolayer culture: activation by transfection with TGF-beta2

Bone marrow-derived mesenchymal progenitor cells are capable of chondrogenesis, making them a possible source of cells for cartilage tissue engineering. Because of this, we studied the effect of human transforming growth factor beta2 (TGF-beta2) on mesenchymal progenitor cell chondrogenesis in monolayer culture using gene transfection technology. A recombinant pcDNA3.1(+)/TGF-beta2 construct containing a full-length TGF-beta2 from a human placental cDNA library was created through gene cloning and DNA recombination. The construct was then lipofected into mesenchymal progenitor cells isolated from human bone marrow. RT-PCR, Western blotting, and immunohistochemistry analyses were performed to identify the expression of TGF-beta2 and cartilage-associated genes and proteins. The results showed that TGF-beta2 was expressed throughout the culture period. The transfected progenitor cells expressed and produced collagen type II and aggrecan 48 h after transfection, and the expression and synthesis were upregulated after 4 weeks. In contrast, the tested genes and proteins were not detected in non-transfected cells. This shows that transfection of pcDNA3.1(+)/TGF-beta2 into mesenchymal progenitor cells is able to provide transient and persistent expression of cartilage-specific genes and proteins, and suggests that the differentiation of human marrow-derived mesenchymal progenitor cells into chondrocytes in monolayer culture is feasible and may be induced by TGF-beta2.

Molecular cytogenetic aberrations in CD30+ anaplastic large cell lymphoma cell lines

Anaplastic large cell lymphomas (ALCL) in children represent a heterogeneous group of neoplasms with regard to the cell lineages involved. The chromosomal 5q35 breakpoint (bp) and the expression of the NPM/ALK fusion gene are the most remarkable molecular cytogenetic features of these malignancies. To identify new locations of ALCL-related oncogenes, comparative genomic hybridization (CGH) was applied to three ALCL cell lines (SU-DHL-1, Karpas 299, and DEL) exhibiting the 5q35 bp and expressing the NPM/ALK transcript. The CGH profiles were compared with those obtained with DNA from U937, HL-60 cells, and altered lymph nodes from two children with ALCL. Significant DNA copy number gains and/or losses were observed on several chromosomes in all ALCL cell lines. Distinct amplicons were detected on 1q21 approximately q44 (DEL), 7q12 (SU-DHL-1), and 1q12 approximately q22 (Karpas 299) regions. The NPM/ALK fusion gene was confirmed by fluorescence in situ hybridization (FISH) analysis in more than 80% of interphase nuclei and metaphase spreads. Enhanced expression of TGF-beta2 and c-MET candidate genes located at the amplified regions was revealed in DEL and SU-DHL1 cell lines by Northern blot analysis. These findings delineate chromosomal imbalances in ALCL-derived cell lines in parallel with high level of amplification covering target DNA sequences, which could play a role in ALCL pathogenesis.

Steady state levels of transforming growth factor-beta1 and -beta2 mRNA and protein expression are elevated in colonic tumors in vivo irrespective of dietary lipids intervention

Colonic tumors of human origin produce abundant transforming growth factor (TGF)-beta suggesting that TGF-beta is critical to their growth. Dietary lipids regulate a number of growth factors including TGF-beta. Whether elevated TGF-beta levels are consistently expressed in colonic tumors irrespective of the environmental milieu in an in vivo model is not known and forms the main objective of the present study. Male F344 rats were injected with azoxymethane, 10 weeks later, rats bearing preneoplastic lesions were fed a low fat (5% corn oil) diet and 3 high fat (5% corn oil with 18% corn oil, fish oil or beef tallow) diets for 16 weeks. Colonic tumors and mucosae were processed and assessed for TGF-beta status. TGF-beta1 and -beta2 mRNA levels were upregulated in colonic tumors more than in mucosae of all diet groups. Dietary lipids modulated TGF-beta mRNA in both tumors and mucosae, high corn and fish oil diets upregulated TGF-beta1 significantly more than the low fat corn oil or high fat beef tallow diets. Immunohistochemical assessments of tissues with different biological features revealed that TGF-beta1 and -beta2 were elevated in tumors and in selected microscopic preneoplastic lesions compared to normal mucosae. This is the first in vivo study, documenting that developing colonic tumors acquire upregulated TGF-beta phenotype even in the presence of lipid environments capable of differentially regulating TGF-beta in normal mucosae. Elevated expression of TGF-beta in a selected subset of microscopic preneoplastic lesions suggests that TGF-beta plays an important role on both early and late stages of colon carcinogenesis.

Transforming growth factor-beta: a promising target for anti-stenosis therapy

Transforming growth factor-beta (TGF-beta) is the general name for a family of cytokines which have widespread effects on many aspects of growth and development. The TGF-beta isoforms are produced by most cell types and exert a wide range of effects in a context-dependent autocrine, paracrine or endocrine fashion via interactions with distinct receptors on the cell surface. TGF-beta is involved in the wound healing process and, thus plays a significant role in the formation of a restenotic lesion after percutaneous transluminal coronary angioplasty (PTCA) or stenting. Perhaps because of its wide-ranging effects, TGF-beta is usually released from cells in a latent form, and its activation and signaling are complex. Manipulation of the TGF-beta1, TGF-beta2, and TGF-beta3 isoforms by inhibiting their expression, activation, or signaling reduces scarring and fibrosis in animal models. However, to date, few have reached clinical trial. This review summarizes current knowledge on the activation and signaling of TGF-beta, and focuses on the anti-TGF-beta strategies which may lead to clinical applications in the prevention of restenosis following PTCA or stenting.

Transcriptional regulation of the transforming growth factor-beta2 gene in glioblastoma cells

The expression of transforming growth factor-beta2 (TGF-beta2) appears to play a strong role in the establishment and progression of glial tumors. In particular, elevated expression of TGF-beta2 appears to be responsible for the impaired cell-mediated immunity often observed in patients with a glioblastoma. This study examined the regulation of the TGF-beta2 at the transcriptional level in the U87MG glioblastoma cell line. We demonstrate that a cAMP response element/activating transcription factor (CRE/ATF) site and an E-box motif located just upstream of the transcription start site are essential for the transcription of the TGF-beta2 gene in U87MG cells. Gel mobility analysis determined that activating transcription factor-1, and possibly cAMP-responsive element binding protein, binds to the CRE/ATF site, and upsteam stimulatory factor (USF) 1 and USF2 bind to the E-box motif. Interestingly, expression of a dominant negative USF protein down-regulates TGF-beta2 activity by 80-95% in glioblastoma cells. We conclude that the binding of transcription factors, in particular the USF proteins, to the TGF-beta2 promoter is essential for its expression and possibly its up-regulation in glioblastomas.

TGFbeta2 activation status during cardiac morphogenesis

Transforming growth factor beta (TGFbeta) is secreted as a biologically inactive complex by many cell types in vitro, but little is known of TGFbeta's activation status in vivo. This study examined the in vivo expression of active and total (active + acid-activatable) TGFbeta2 in embryonic chicken hearts during cardiac morphogenesis (Hamburger-Hamilton stage 10-24). The concentration of TGFbeta2 was measured by an enzyme-linked immunoassay that recognized active TGFbeta2. Whole heart homogenates were either left untreated to measure active TGFbeta2 or treated with acid before assay to measure total (active + acid-activatable) TGFbeta2. Total TGFbeta2 concentration increased more than 16-fold between stage 10/11 and stage 24. Active TGFbeta2 concentration was highest at stage 14/15, but overall remained relatively constant varying at most by 2.8-fold. When expressed relative to total TGFbeta2, the amount of active TGFbeta2 progressively declined from 70% in stage 10/11 hearts to 7% in stage 24 hearts. The distribution of active and total TGFbeta2 was examined by immunostaining with an antibody against active TGFbeta2. Before immunostaining, sections were either treated with acid or left untreated to determine the distribution of total and active TGFbeta2, respectively. Active TGFbeta2 immunostaining was first detected in the endothelium, myocardium, and cardiac jelly of stage 14 hearts. Acid treatment had no effect on the distribution or intensity of immunostaining at this stage. Faint, active TGFbeta2 immunostaining was restricted to the ventricular myocardium in stage 18 hearts. Acid treatment resulted in a marked increase in staining intensity in the ventricle, but no staining was observed in the atrium or outflow tract. In stage 24 hearts, faint active TGFbeta2 staining was detected in the ventricle before acid treatment. After acid treatment, patches of intense punctate stain were found in all regions of the embryonic heart. Increases in TGFbeta2 concentration and immunostaining intensity after acidification suggest that a significant amount of TGFbeta2 is in the latent form. Stage-dependent differences in activation status suggest that activation may be a developmentally regulated process in the chick heart and support the notion that activation is an important step in regulating TGFbeta actions in vivo.

Analysis of TGF-beta type I receptor for mutations and polymorphisms in head and neck cancers

Transforming growth factor-beta receptor (TbetaR)-dependent signals are critical for cell growth and differentiation and are often disrupted during tumorigenesis. The entire coding region of TbetaR-I and flanking intron sequences from 30 head and neck carcinomas were examined for alterations using "Cold" SSCP and direct sequencing. No somatic point mutations were found in the TbetaR-I gene. In contrast, 14 polymorphic sequence changes were detected in TbetaR-I in 13 (43%) of the samples, including eight (27%) nucleotide alterations identified as polymorphisms in an exon-1 (GCG)(9) microsatellite repeat, a previously reported tumor susceptibility allele. A nine base pair deletion was found in 23% of the samples including five heterozygous and two homozygous deletions as well as single homozygous 12bp deletion. Additionally, six heterozygous polymorphisms in intronic sequences were determined, including one heterozygous C/A genotype at the +82 nucleotide position of the intron-5 intervening sequence (IVS), and five heterozygous G/A genotypes within intron-7 at the +24 nucleotide position. Exon-1 polymorphisms in the (GCG)(9) microsatellite region of the TbetaR-I gene and their association with head/neck cancers, suggest that development of these cancers may be a direct consequence of loss of responsiveness to TGF-beta mediated growth inhibition.

TGF-beta isoform and receptor expression in giant cell tumor and giant cell lesions of bone

The authors examined the distribution of tumor growth factor-beta (TGF-beta) isoforms and receptors in 35 giant cell tumor (GCT) of bone in comparison with a group of benign giant cell-containing lesions of bone, including 5 aneurysmal bone cysts, 2 cases of brown tumor of hyperparathyroidism, 3 nonossifying fibromas, and 7 cases of giant cell reparative granuloma. The results of immunohistochemical analysis of GCT showed a complete absence of TGF-beta1 expression in both mononuclear tumor cells and giant cells. Only reactive bone present within the tumor showed an intense immunoreactivity. Transforming growth factor-beta2 and TGF-beta3 were detected in the majority of cases (97.1% and 82.8%, respectively), whereas TGF-beta receptor type I (TGF-beta RI) and type II (TGF-beta RII) were diffusely expressed in all cases. Reverse transcription-polymerase chain reaction (RT-PCR) analysis performed on 10 GCTs with specific oligonucleotide primers demonstrated the presence of mRNA transcripts for TGF-beta1, 2, 3, and for TGF-beta RI and RII. Quantitative measurements of TGF-beta1 in conditioned media from primary cultures of GCT showed undetectable or very low amounts of the cytokine (0-23 pg/mL). The results of immunohistochemical analysis showed that all giant cell-containing lesions of bone were at least focally positive for the 3 isoform of TGF-beta, with positivity present both in osteoclast-like giant cells and mononuclear cells, and diffusely positive for TGF-beta RI and RII. Reverse transcription-polymerase chain reaction analysis conducted on samples from 3 nonossifying fibromas and 1 giant cell reparative granuloma confirmed the expression of the corresponding mRNA. In conclusion, according to the current data, GCT of bone can be distinguished from other giant cell-containing lesions of bone on the basis of the absence of TGF-beta1 expression at the protein level, which appears to be the result of posttranslational regulation processes.

Nonandrogenic mediators of prostatic growth

Prostate growth and development are primarily under the control of androgens; however, other factors can also influence prostatic growth through alternative pathways. This article discusses some of the major nonandrogenic mediators of prostate growth. Information on the pathways by which these factors exert their effects is also reviewed.

Evidence that furin is an authentic transforming growth factor-beta1-converting enzyme

Transforming growth factor (TGF)-beta1 plays an essential role in cell growth and differentiation. It is also considered as a gatekeeper of immune homeostasis with gene disruption leading to autoimmune and inflammatory diseases. TGF-beta1 is produced as an inactive precursor polypeptide that can be efficiently secreted but correct proteolytic cleavage is an essential step for its activation. Assessment of the cleavage site has revealed a unique R-H-R-R sequence reminiscent of proprotein convertase (PC) recognition motifs and has previously demonstrated that this PC-like cleavage site is correctly cleaved by furin, a member of the PC family. Here we report that among PC members, furin more closely satisfies the requirements needed to fulfill the role of a genuine TGF-beta1 convertase. Even though six members of the PC family have the ability to cleave TGF-beta1, ectopic expression of alpha(1)-antitrypsin Portland (alpha(1)-AT-PDX), a potent furin inhibitor, blocked 80% of TGF-beta1 processing mediated by endogenous enzymes as demonstrated in an in vitro digestion assay. Genetic complementation of a furin-deficient LoVo cell line with the wild-type gene restores the production of mature and bioactivable TGF-beta1. Moreover, both furin and TGF-beta are coordinately expressed and regulated in vitro and in vivo in the hematopoietic and immune system, an important tissue target. These results demonstrate for the first time that furin is an authentic and adaptive TGF-beta1-converting enzyme whereas other members of the PC family might substitute or supplement furin activity. Our study advances our comprehension of the complexity of the TGF-beta system and should facilitate the development of therapeutically useful TGF-beta inhibitors.

The transforming growth factor-betas: structure, signaling, and roles in nervous system development and functions

Transforming growth factor-betas (TGF-betas) are among the most widespread and versatile cytokines. Here, we first provide a brief overview of their molecular biology, biochemistry, and signaling. We then review distribution and functions of the three mammalian TGF-beta isoforms, beta1, beta2, and beta3, and their receptors in the developing and adult nervous system. Roles of TGF-betas in the regulation of radial glia, astroglia, oligodendroglia, and microglia are addressed. Finally, we review the current state of knowledge concerning the roles of TGF-betas in controlling neuronal performances, including the regulation of proliferation of neuronal precursors, survival/death decisions, and neuronal differentiation.

Transforming growth factor-beta2 mediates mesenchymal-epithelial interactions of testicular somatic cells

Transforming growth factor-beta2 (TGFbeta2) is an important mediator of growth and differentiation. We here describe for the first time the complete sequence of the TGFbeta2 complementary DNA derived from peritubular myoid cells of the rat testis. The size of the rat TGFbeta2 complementary DNA was 1245 bp, and the deduced protein sequence contained 414 amino acids. Sequence comparison with the human and mouse amino acid sequences demonstrated 96.4% and 97.9% sequence identities, respectively. To elucidate the functional role of TGFbeta2 in testicular somatic cells, we studied its secretion in vitro in monocultures and cocultures of mesenchymal peritubular and epithelial Sertoli cells. The highest amounts of TGFbeta2 protein were secreted in the cocultures and by peritubular cells, whereas Sertoli cells secreted only minor amounts. Stimulation experiments with FSH revealed a reduced secretion of TGFbeta2 in cocultures, probably mediated by a paracrine interaction of the FSH-responsive Sertoli cells. In contrast, TGFbeta2 secretion by peritubular cells was increased after stimulation with glucocorticoids and after addition of recombinant TGFbeta2, indicating an autoregulation of TGFbeta2. Furthermore, application of recombinant TGFbeta2 to cocultures resulted in an enhanced aggregation and cell clustering of Sertoli cells, pointing to an important role of TGFbeta2 in the paracrine interaction of peritubular and Sertoli cells of the developing rat testis.

Correlation of thrombospondin-1 and transforming growth factor-beta expression with malignancy of glioma

The expression of thrombospondin-1 (TSP-1) and its role in gliomas have not been well examined. In the present study TSP-1 expression in a panel of malignant glioma cell lines and the expression of TSP-1 and transforming growth factor (TGF-beta) proteins in low-grade and malignant glioma tissues were investigated. Reverse transcription-polymerase chain reaction analysis showed that nine of nine malignant glioma cell lines expressed TSP-1 mRNA, and seven of nine glioma lines expressed TSP-2 mRNA. Production and secretion of TSP-1 were examined in the T98G glioblastoma cell line by western blot analysis. Total TSP-1 protein content in the supernatant was 10 times higher than that in the cell lysate. Secretion of TSP-1 was examined in these glioma cell lines by western blot analysis. All glioma lines secreted significant levels of TSP-1. Bioassay showed that all tumor lines had the capacity to activate latent TGF-beta. Localization of TSP-1, TGF-beta1, -beta2, and -beta3 was examined immunohistochemically in surgically resected glioma tissues, including 11 glioblastomas, six anaplastic astrocytomas, and eight astrocytomas. Most glioblastomas expressed high levels of both TSP-1 and TGF-beta. Anaplastic astrocytomas expressed moderate levels of TSP-1 and TGF-beta. Most malignant gliomas expressed various levels of TGF-beta1, -beta2, and -beta3. The expression of both proteins, however, was weak in low-grade gliomas. Normal brain tissues around the tumors were negatively or very weakly positively stained for TSP-1 and TGF-beta. These results indicate that most malignant glioma cells express TSP-1 in vitro and in vivo, and the expression of TSP-1 and TGF-beta in vivo correlates with the histologic malignancy of glioma. Overexpression of both TSP-1 and TGF-beta may increase the biologic malignancy of malignant gliomas, through generating the active form of TGF-beta in tumor tissues.

Age-related effects of TGF-beta on proteoglycan synthesis in equine articular cartilage

The synthesis of proteoglycans was measured in normal equine articular cartilage of ages 9 months to 20 years and the effect of TGF-beta1 on this activity was investigated. The rate of incorporation of [(35)S]Na(2)SO(4) decreased with age as did the responsiveness of the tissue to the growth factor. The enhanced synthesis of proteoglycan induced at all ages by TGF-beta1 was down-regulated by IL-1 beta and retinoic acid. The expression of mRNA for TGF-beta1, 2, and 3 was also measured, and although the level of TGF-beta1 was highest at all ages, the expression of each growth factor decreased with age.

Bladder acellular matrix graft in rats: its neurophysiologic properties and mRNA expression of growth factors TGF-alpha and TGF-beta

To assess the neurophysiologic properties and molecular mechanisms of the bladder acellular matrix graft (BAMG), we performed cystometric and neurophysiologic studies in male Sprague-Dawley rats (n = 46) at varying intervals. The animals were assigned to 3 groups: 1) normal, 2) partial cystectomy (>50%), and 3) partial cystectomy (>50%) and grafting with a BAMG of equal size. Additionally, matrix-grafted and host bladders were processed for analysis of mRNA expression of transforming growth factor (TGF)-alpha, TGF-beta1, TGF-beta2, and TGF-beta3 by reverse transcriptase polymerase chain reaction. Matrix-grafted bladders showed a significantly higher bladder capacity at 3 and 6 weeks and 4 months than those with partial cystectomy alone, and a significantly higher bladder capacity at 4 months than in normal controls (P < or = 0.01). Residual urine volume was significantly increased at 4 months. Electrostimulation of the pelvic nerve provoked generalized bladder contractions, a response that was reduced by atropine and hexamethonium. Variable induction of TGF-alpha, TGF-beta1, TGF-beta2, and TGF-beta3 gene transcription was evident in the BAMG, with prominent mRNA expression of TGF-alpha and TGF-beta1 6 months after surgery. These cystometric results and detrusor responses to stimulation provide further evidence that graft components do not interfere with host components. Matrix-grafted rat bladders generate, although not increased over time, adequate intravesical pressure responses to produce sustained voiding. Gene expression of different growth factors may be significant in understanding their role in the development and differentiation of the BAMG for partial bladder replacement.

Retinoic acid resistance at late stages of human papillomavirus type 16-mediated transformation of human keratinocytes arises despite intact retinoid signaling and is due to a loss of sensitivity to transforming growth factor-beta

In our in vitro model of human cell carcinogenesis, normal human foreskin keratinocytes (HKc) transfected with human papillomavirus type 16 DNA (HKc/HPV16) progress toward malignancy through several phenotypically defined and reproducible "steps" that include immortalization, growth factor independence (HKc/GFI), differentiation resistance (HKc/DR), and ultimately malignant conversion. While HKc/HPV16 are very sensitive to growth inhibition by all-trans-retinoic acid (RA) at early passages, they lose their sensitivity to RA during progression in culture. However, gel mobility shift assays using the retinoid response elements DR1 and DR5 showed no changes in binding activity of nuclear extracts obtained from HKc/HPV16 at different stages of in vitro progression. Similarly, Western blot analyses for retinoic acid receptor gamma-1 and the retinoid X receptors failed to reveal any decreases in the levels of these retinoid receptors throughout progression. In addition, luciferase activity driven by the SV40 promoter with a DR5 enhancer element was activated following RA treatment of HKc/DR that were resistant to growth inhibition by RA. Since RA induces transforming growth factor-beta2 (TGF-beta2) in normal HKc and HKc/HPV16, we investigated whether this response changed during progression. Again, RA induced TGF-beta2 mRNA in early and late passage HKc/HPV16, HKc/GFI, and HKc/DR approximately to the same extent, confirming that the RA signaling pathways remained intact during in vitro progression despite the fact that the cells become resistant to growth inhibition by RA. We then investigated the sensitivity of HKc/HPV16 to growth inhibition by TGF-beta. While early passage HKc/HPV16 were as sensitive as normal HKc to growth inhibition by TGF-beta1 and TGF-beta2, the cells became increasingly resistant to both TGF-beta isotypes during in vitro progression. In addition, while both RA and TGF-beta produced a decrease in the levels of mRNA for the HPV16 oncogenes E6 and E7 in early passage HKc/HPV16, this effect was also lost at later stages of progression. Finally, blocking anti-TGF-beta antibodies partially prevented RA inhibition of growth and E6/E7 expression in early passage HKc/HPV16. Taken together, these data strongly suggest that inhibition of growth and HPV16 early gene expression in HKc/HPV16 by RA is mediated by TGF-beta and that a loss of RA sensitivity is linked to TGF-beta resistance rather than alterations in RA signaling.

Autocrine regulation of TGF beta expression in adult cardiomyocytes

As shown before, TGF beta acts in an autocrine manner on the induction of hypertrophic responsiveness to beta-adrenoceptor stimulation in cultured ventricular cardiomyocytes of adult rat. We now investigated how TGF beta expression and activation is regulated in these cultures and how beta-adrenoceptor stimulation influences TGF beta -mRNA expression. It was found that freshly isolated cardiomyocytes secrete latent TGF beta in the culture medium. Supplementation of the cultures with 20% FCS resulted in activation of the secreted TGF beta to 4.1+/-0.2 ng/ml active TGF beta after 6 days. Presence of the protease inhibitor aprotinin (50 microg/ml) reduced TGF beta activity by 44+/-5% (n=5, P<0.05). In cultures supplemented with 5% FCS, TGF beta was not activated. Active TGF beta downregulated its mRNA-expression: after 6 days TGF beta(1)-mRNA was reduced to 55.1+/-11.0%, TGF beta(2)-mRNA to 30.1+/-16.5%, and TGF beta(3)-mRNA to 0.3+/-0.4% in 20% FCS-cultures as compared to their expression in freshly isolated cells (n=4, P<0.05). TGF beta-mRNA expression did not change in cultures without active TGF beta. Isoprenaline (1 microm) increased TGF beta(1)-mRNA only in cultures which had been pre-exposed to active TGF beta. This effect was also seen when hearts from normal mice were compared with hearts from transgenic mice overexpressing TGF beta(1): only in hearts from transgenic animals perfusion with isoprenaline increased TGF beta(1)-mRNA. In conclusion, isolated cardiomyocytes release latent TGF beta, which is activated by external proteases. Active TGF beta downregulates its own mRNA expression. Preexposure to TGF beta is necessary for a beta-adrenoceptor-mediated increase in TGF beta(1)-mRNA in cardiomyocytes.

Neonatal estrogen exposure alters the transforming growth factor-beta signaling system in the developing rat prostate and blocks the transient p21(cip1/waf1) expression associated with epithelial differentiation

Exposure of male rats to estrogens during the neonatal period retards prostate branching morphogenesis, blocks epithelial differentiation, and predisposes the adult prostate to hyperplasia and dysplasia. The mechanism of neonatal estrogenization is not well understood. The present study evaluated transforming growth factor-beta (TGFbeta) in the neonatally estrogenized ventral prostate to determine whether this paracrine/autocrine factor may in part mediate the effects ofestrogen on the developing prostate gland. Immunocytochemistry using antibodies against active TGFbeta1 and its latency-associated peptide localized this molecule to the periductal smooth muscle cells in the developing prostate. Although neonatal estrogenization increased the accumulation of total and active TGFbeta1 in the smooth muscle layer as early as day 6 of life, it was physically separated from the epithelial ducts by a proliferating layer of fibroblasts surrounding the basement membrane. RT-PCR demonstrated that alterations in TGFbeta1 levels were not due to alterations in TGFbeta1 transcription. TGFbeta2 and TGFbeta3 were primarily immunolocalized to differentiating epithelial cells in developing prostates, and this was markedly dampened between days 10-30 after neonatal estrogen exposure. Immunocytochemistry for TGFbeta signaling components revealed that neonatal estrogenization transiently reduced TGFbeta type I receptor levels in the prostate epithelium, but not in stroma, between days 6-15, whereas there was no effect on TGFbeta type II receptor. Levels of the intracellular signal Smad2 (52 kDa) were detected in epithelial cells but were not altered after estrogenization. To analyze the functional status of the TGFbeta signaling pathway, immunocytochemistry was performed for p21(cip-1/waf-1), a cyclin-dependent kinase inhibitor that is inducible by TGFbeta1 in the prostate. Transient nuclear localization of p21(cip-1/waf-1) was normally observed in epithelial cells between days 6-15 and was associated with entry of cells into a terminal differentiation pathway. Neonatal estrogenization prevented this transient expression of p21(cip-1/waf-1). The present findings demonstrate that the TGFbeta signaling system is perturbed at several levels in the estrogenized prostate, which may in part account for the epithelial cell differentiation blockade as well as the proliferation of periductal fibroblasts in this model.

Transforming growth factor-beta in benign and malignant prostate

BACKGROUND

The present review summarizes the cellular action of TGF-beta in benign and malignant growth of the prostate.

METHODS

TGF-beta is a pleiotropic growth factor. It plays an important role in the regulation of growth and differentiation in many cells. In benign prostatic epithelia, its action is mediated through a paracrine mechanism. It inhibits proliferation and induces apoptosis in prostatic epithelia. It provides a mechanism to maintain epithelial homeostasis in the prostate. In prostatic stroma, its continual action leads to smooth muscle differentiation. This effect of TGF-beta may regulate the development of prostatic smooth muscle nodules in benign prostatic hyperplasia.

RESULTS

As prostatic epithelial cells undergo malignant transformation, two major events occur regarding TGF-beta action. These include the loss of expression of functional TGF-beta receptors and overproduction of TGF-beta in malignant cells. The loss of expression of functional TGF-beta receptors provides a growth advantage to cancer cells over their benign counterparts. The overproduction of TGF-beta by cancer cells has a multitude of adverse consequences. TGF-beta can promote extracellular matrix production, induce angiogenesis, and inhibit host immune function. The biological consequence of these activities is an enhanced tumorigenicity in prostate cancer. Results of our recent studies with a rat prostate cancer model suggest that the immunosuppressive effect of TGF-beta seems to be the primary cause of tumor progression. This is because, if these cancer cells were engineered to reduce the production of TGF-beta, tumor growth was inhibited in syngeneic hosts but not in immune compromised hosts.

CONCLUSIONS

Our future research should take advantage of this knowledge to devise therapeutic strategies aimed at eradicating prostate cancer.

Suppression of transforming growth factor-beta isoforms, TGF-beta receptor type II, and myofibroblast differentiation in cultured human corneal and limbal fibroblasts by amniotic membrane matrix

Down-regulation of the transforming growth factor-beta (TGF-beta) signaling system is a strategy for preventing scarring during wound healing. Human corneal and limbal fibroblasts were cultured on the stromal matrix side of preserved human amniotic membrane. The levels of TGF-beta1, beta2, and beta3 and TGF-beta type II receptor transcripts and TGF-beta1 and beta2 proteins were suppressed as early as 8 hr and more dramatically at 24 hr after contact with an amniotic membrane. This suppressive effect was accompanied by down-regulation of alpha-smooth muscle actin, EDA spliced form of fibronectin, and integrin alpha5. It persisted even when challenged by 10 ng/ml TGF-beta1. In contrast with their counterparts grown on plastic or in collagen gel, such suppression in amniotic membrane cultures remained complete after 1 week of culturing. Cells cultured on amniotic membrane showed significantly reduced [3H]-thymidine incorporation compared to cells cultured on plastic and displayed no DNA fragmentation. These results reveal a novel mechanism by which the TGF-beta signaling system, DNA synthesis, and subsequent myofibroblast differentiation can be suppressed by an amnionic membrane matrix. This action explains in part the antiscarring results of amniotic membrane transplantation used for ocular surface reconstruction, a surgical technique applicable to other subspecialties. It may also explain in part why fetal wound healing is scarless.

Bone morphogenetic protein 2 exerts diverse effects on cell growth in vitro and is expressed in human pancreatic cancer in vivo

BACKGROUND & AIMS

Bone morphogenetic proteins (BMPs) belong to the transforming growth factor beta superfamily of signaling molecules. We characterized the expression of BMP-2 and its receptors in human pancreatic tissues and pancreatic cancer cell lines and examined the effects of BMP-2 on mitogenesis.

METHODS

Expression of BMP-2 and its receptors was determined by Northern blot analysis using specific complementary DNA probes. Distribution of BMP-2 in pancreatic cancers was examined by immunohistochemistry and in situ hybridization. Effects of BMP-2 on mitogenesis were assessed by monitoring cell proliferation and activation of mitogen-activated protein kinase (MAPK).

RESULTS

Compared with the normal pancreas, pancreatic cancers showed a 12.5-fold (P < 0.01), 2-fold (P < 0.01), and 8-fold (P < 0.01) increase of BMP-2, BMP receptor (R)-IA, and BMPR-II messenger RNA levels, respectively. By immunohistochemistry and in situ hybridization, BMP-2 was expressed in the cancer cells within the tumor mass. There was a significant correlation between the presence of BMP-2 immunostaining in the tumors and shorter postoperative survival. Pancreatic cancer cell lines expressed variable levels of messenger RNA encoding BMP-2 and its receptors. BMP-2 stimulated the growth of two pancreatic cancer cell lines (ASPC-1 and CAPAN-1). This mitogenic effect was associated with MAPK activation and blocked by the MAPK inhibitor PD98059 in CAPAN-1 but not in ASPC-1 cells. In both cell lines, expression of wild-type Smad4 abolished the BMP-2-mediated growth stimulation. BMP-2 inhibited the growth of COLO-357 cells, an effect that was blocked by expressing a dominant negative Smad4. BMP-2 had no effect in three cell lines that underexpressed either the BMP receptors or Smad1.

CONCLUSIONS

These findings indicate that BMP-2 has the capacity to act as a mitogen when Smad4 is mutated and suggest that it might play a role in the pathobiology of human pancreatic cancer.

Normal human colonic subepithelial myofibroblasts enhance epithelial migration (restitution) via TGF-beta3

After injury and loss of epithelial cells, intestinal barrier function is reestablished by migration of viable epithelial cells from the wound edge (restitution). Myofibroblasts are located close to the basal surface of epithelial cells. This study aimed to investigate the role of human colonic subepithelial myofibroblasts in epithelial restitution. Primary cultures of subepithelial myofibroblasts were established. Monolayers of the epithelial cell lines IEC-6 and T84 were "wounded" in a standard manner to create an in vitro model of restitution. Migration of epithelial cells across the wound edge was assessed following culture in myofibroblast-conditioned medium. Myofibroblast expression of transforming growth factor (TGF)-beta isoforms was examined using RT-PCR, and TGF-beta isoform bioactivity was assessed using Mv 1 Lu bioassay. Myofibroblast-conditioned medium, via a TGF-beta-dependent pathway, significantly enhanced migration of epithelial cells across the wound edge and significantly inhibited cell proliferation in wounded monolayers. Messenger RNA for TGF-beta1, -beta2, and -beta3 was detected in the myofibroblasts, and Mv 1 Lu bioassay showed the presence of predominantly bioactive TGF-beta3. This study shows that human colonic subepithelial myofibroblasts secrete predominantly bioactive TGF-beta3 and enhance restitution in wounded epithelial monolayers via a TGF-beta-dependent pathway.

Reversal of tamoxifen resistance of human breast carcinomas in vivo by neutralizing antibodies to transforming growth factor-beta

BACKGROUND

Overexpression of transforming growth factor (TGF)-beta has been reported in human breast carcinomas resistant to antiestrogen tamoxifen, but the role of TGF-beta in this resistant phenotype is unclear. We investigated whether inhibition of TGF-beta2, which is overexpressed in LCC2 tamoxifen-resistant human breast cancer cells, could modify antiestrogen resistance.

METHODS

TGF-beta2 expression was evaluated in LCC2 cells and tamoxifen-sensitive LCC1 cells by northern blot analysis. Secreted TGF-beta activity was quantified by use of an 125I-TGF-beta competitive radioreceptor assay. Sensitivity to tamoxifen was measured in a soft agarose colony-forming assay and in a xenograft model in nude and beige/nude mice. Natural killer (NK) cell cytotoxicity was measured by 51Cr release from LCC1 and LCC2 cell targets coincubated with human peripheral blood mononuclear cells. Decrease in TGF-beta2 expression in LCC2 cells was achieved by treatment with antisense oligodeoxynucleotides and confirmed by TGF-beta2 immunoblot analysis.

RESULTS AND CONCLUSIONS

The proliferative response of LCC2 cells to tamoxifen in vitro was not altered by TGF-beta neutralizing antibodies. However, established LCC2 tumors in nude mice treated with tamoxifen plus TGF-beta antibodies failed to grow, whereas tumors treated with tamoxifen plus a control antibody continued to proliferate. This reversal of tamoxifen resistance by TGF-beta antibodies did not occur in beige/nude mice, which lack NK-cell function, suggesting that immune mechanisms may be involved in the antitumor effects of tamoxifen. Antisense TGF-beta2 oligodeoxynucleotides enhanced the NK sensitivity of LCC2 cells in the presence of tamoxifen. Finally, LCC1 tumors were markedly more sensitive to tamoxifen in NK-active than in NK-deficient mice.

IMPLICATIONS

These data suggest that host NK function mediates, in part, the antitumor effect of tamoxifen and that TGF-beta2 may abrogate this mechanism, thus contributing to tamoxifen resistance.

Cord blood-derived human cultured mast cells produce transforming growth factor beta1

BACKGROUND

Mast cells frequently accumulate at the site of fibrosis and their contribution has been suspected in the pathogenesis of fibrotic conditions. However, it still remains unknown whether human mast cells synthesize transforming growth factor beta1 (TGF-beta1).

OBJECTIVE

We have investigated whether cord blood-derived human cultured mast cells express messenger RNA (mRNA) for TGF-beta and produce bioactive TGF-beta1.

METHODS

Mast cells were obtained by culturing mononuclear cells from cord blood in the presence of stem cell factor and interleukin-6. Expression of mRNA for TGF-beta1 was examined by the method of reverse transcriptase-polymerase chain reaction (RT-PCR). Immunocytochemical staining for TGF-beta and growth-inhibitory assay using Mv1Lu cells were also performed.

RESULTS

The cultured human mast cells constitutively expressed mRNA for TGF-beta1. With calcium ionophore A23187, the intensity of the PCR-amplified band for TGF-beta1 was not increased. Immunocytochemical staining showed that the cultured mast cells were positive for both latency-associated peptide and activated forms of TGF-beta. Bioassay with Mv1Lu cells and R 4-2 mutant cells showed that mast-cell conditioned medium had a bioactivity of TGF-beta1.

CONCLUSION

Cord blood-derived human cultured mast cells constitutively express mRNA for TGF-beta1 and produce functional TGF-beta1. Because TGF-beta1 has been shown to be highly fibrogenic, these results may highlight a novel role for human mast cells in tissue fibrosis.

DAN is a secreted glycoprotein related to Xenopus cerberus

We report that DAN, a potential cell cycle regulator and tumour suppressor, is a secreted glycoprotein related to Xenopus cerberus. DAN, cerberus, its mouse relative Cer-1/cer-l/Cerberus-like/Cerr1, and the recently described factor DRM/Gremlin, appear to be members of the cystine knot superfamily, which includes TGFbetas and BMPs. Like cerberus and mCer-1, DAN-induced cement glands as well as markers of anterior neural tissue and endoderm in Xenopus animal cap assays, features of BMP signalling blockade. During mouse embryogenesis, Dan was expressed from E8.5 in cranial mesenchyme and somites, then later in limb and facial mesenchyme. The pattern in somites was highly dynamic, with transcripts initially localized to the caudal half of the nascent epithelial somite, then, after maturation, to sclerotomal cells adjacent to the neural tube. Dan was also expressed in the developing myotome. The expression domains include sites in which BMP inhibition is known to be important for development. Thus, DAN appears to be a secreted factor belonging to the cystine knot superfamily, and one of a growing number of antagonists acting to modulate BMP signalling during development.

Down-regulation of transforming growth factor-beta and interleukin-10 secretion from malignant glioma cells by cytokines and anticancer drugs

The effect of treatment with interleukin-1 beta (IL-1 beta), interferon-gamma (IFN-gamma), vincristine, and etoposide was evaluated on the secretion of transforming growth factor-beta (TGF-beta) and IL-10 and the expression of major histocompatibility complex (MHC) class I, intercellular adhesion molecule-1 (ICAM-1), and CD80 molecules by malignant glioma cells. Five malignant glioma cell lines were treated with IL-1 beta, IFN-gamma, and/or anticancer agents (vincristine and etoposide). Combined treatment with IL-1 beta and IFN-gamma caused greater inhibition of TGF-beta secretion compared to treatment with IFN-gamma, and almost the same levels of inhibition as treatment with vincristine and etoposide. The greatest inhibition of TGF-beta secretion was achieved by treatment with all agents. Low levels of IL-10 secretion were determined in two out of five malignant glioma cell lines. This IL-10 secretion was inhibited by treatment with IL-1 beta, IFN-gamma, vincristine, and/or etoposide. Treatment with both cytokines and anticancer agents increased the expression of MHC class I and ICAM-1 in all tumor cell lines. The mean increase of expression of MHC class I was 50% and that of ICAM-1 was 12-fold. No tumor cell lines expressed CD80 molecules on the cell surface, and no treatment caused CD80 expression. These results suggest that TGF-beta and IL-10 secretion by malignant glioma cells can be suppressed by treatment with a combination of IL-1 beta, IFN-gamma, vincristine, and etoposide, and the treatment up-regulates MHC class I and ICAM-1 expression on tumor cells. These results have implications for immunotherapy and chemotherapy in patients with malignant tumors.

Expression of eukaryotic proteins in soluble form in Escherichia coli

At the optimum temperature for its growth (37 degrees C), Escherichia coli tends to accumulate heterologous proteins in insoluble form. Fusion protein technology has been used to increase the solubility of overexpressed proteins in this organism, but with variable degrees of success. Fusion to a mutant form of DsbA (DsbAmut) confers higher levels of solubility to heterologous proteins in a reproducible way, even when E. coli is grown at 37 degrees C. We have shown this to be true with a diverse sample of eukaryotic proteins: IGF-I, IGFBP-3, 3C proteinase, TGF beta-2, sTGF beta-RII, BDNF, GDNF, mEGFBP, leptin, and GFP. In addition, we have investigated the effects of charge average and proline content on the solubility of DsbAmut fusions. Coexpression of a protein prolyl isomerase [cyclophilin (L-)] and modification of selected asparagine residues to aspartic acid appear to have beneficial effects on the accumulation of soluble heterologous proteins.

Determination of transforming growth factor-beta 2 (TGF-beta 2) in bovine colostrum samples

Transforming growth factor-beta 2 (TGF-beta 2) is the major TGF-beta form in bovine colostrum. A colostrum pool of the five first milkings was made to validate an ELISA specific for human TGF-beta 2 for measure TGF-beta 2 concentration in bovine colostrum samples. According to this test > 90% of total TGF-beta 2 (74.5 +/- 4.4 ng/ml) in colostrum pool was in a latent form that could be activated by acetic acid treatment, whereas the concentration of the active form was only 4.19 +/- 0.27 ng/ml. Activated colostrum samples of the first milkings of five cows contained 150-1150 ng TGF-beta 2/ml and its concentration declined in correlation (r = 0.86) with total protein concentration to 12-71 ng/ml by the fifth milkings. Most of the TGF-beta 2 (94%) was found in the whey fraction of colostrum. The ELISA results were also compared with a TGF-beta 2 bioassay, the fibroblasts migration assay. This assay detected 9.8 +/- 1.0 ng/ml and 4.4 +/- 0.7 ng/ml in the activated and non-activated samples of colostrum pool respectively.

Transforming growth factor-beta response and expression in junctional and oral gingival epithelial cells

The junctional (JE) and oral gingival (OGE) epithelium show distinct morphological phenotypes and express different cell surface and keratin markers. Transforming growth factor-beta (TGF-beta) has been shown to stimulate extracellular matrix formation and inhibit proteolytic matrix degradation in periodontal wound healing. To elucidate potential roles of TGF-beta in gingival epithelial regeneration and reattachment, the present study examined the effects of TGF-beta on JE and OGE cell growth and determined the patterns of expression of mRNAs for the TGF-beta isotypes beta 1, beta 2 and beta 3 and TGF-beta receptor types I, II and III. Primary cell cultures were initiated from JE and OGE and the cell phenotypes confirmed using monoclonal antibodies to specific keratins. TGF-beta induced a significant growth inhibition in OGE cells derived from 6 different patients with a mean inhibition of 46% and a range of 16-70% (p = 0.031). Although responses varied between patients, in general maximum inhibition occurred at 10 ng/ml TGF-beta. JE cells from 5 patients showed no significant growth inhibition by TGF-beta (p = 0.125). Greater expression of TGF-beta 2 and receptor type I mRNA was found in OGE than JE cells and thus appeared to be associated with differentiating epithelial cells. JE cells expressed more TGF-beta type II receptor specific mRNA than did OGE cells, but TGF-beta 1 mRNA expression was similar in JE and OGE cells. JE or OGE cultures derived from 2 of 3 patients showed expression of mRNA for the TGF-beta type III receptor. TGF-beta 3 mRNA was not detected in any of the JE or OGE samples examined. The greater sensitivity of OGE than JE to the growth inhibiting effects of TGF-beta correlated with higher expression of receptor type I mRNA which, together with the type II receptor, is required for sensitivity to growth inhibition by TGF-beta. The results suggest that, in addition to structural differences, the development of functional differences in the responses of JE and OGE to TGF-beta may be associated with the formation of JE from OGE cells and the reformation of attachment after periodontal surgery.

1 alpha,25-Dihydroxyvitamin D3 increases transforming growth factor and transforming growth factor receptor type I and II synthesis in human bone cells

To determine whether the inhibition of human osteoblast growth mediated by 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)D3) occurs as a result of changes in transforming growth factor (TGF) and TGF receptor synthesis, we examined the effects of 1 alpha,25(OH)2D3 on the synthesis of TGF beta and TGF-beta receptors. Treatment with 1 alpha,25(OH)2D3, but not vehicle, increased TGF-beta 2 concentrations in human osteoblast cell supernantants in a dose- and time-dependent manner. The increase in TGF-beta 2 concentrations was associated with an inhibition of osteoblast cell growth; antibodies directed against transforming growth factor beta partially blocked the inhibition of cellular growth mediated by 1 alpha,25-(OH)2D3 TGF-beta 2 gene transcription and TGF-beta 2 mRNA concentrations were increased in 1 alpha,25(OH)D3 but not in vehicle-treated cells. 1 alpha,25(OH)2D3 increased TGF-beta type I and type II receptor mRNA levels in osteoblasts. Increased expression of TGF-beta 2 and TGF-beta receptors by 1 alpha,25(OH)2D3 might account for the inhibition of human osteoblast growth seen following 1 alpha,25(OH)2D3 treatment.

Immunohistochemical localization of TGF beta 1, TGF beta 2, and TGF beta 3 in normal and malignant human prostate

BACKGROUND

Prostate cancer eventually becomes androgen-independent, suggesting that growth factors such as TGF beta 1-3 may potentially contribute to prostate neoplasia. The pattern and level of TGF beta 1-3 protein expression in normal and malignant human prostate are unknown.

METHODS

An immunohistochemical study was undertaken to analyze TGF beta 1, TGF beta 2, and TGF beta 3 protein in malignant and adjacent normal prostates from 25 patients who had clinically localized prostate cancer.

RESULTS

Normal prostate exhibited similar TGF beta 1 immunostaining in stromal and epithelial cells, whereas TGF beta 2 and TGF beta 3 protein staining was greater in the epithelial relative to the stromal compartments. In malignancy, prostate epithelial cells had higher TGF beta 1 and TGF beta 2 immunostaining than either the surrounding stromal cells or their normal prostatic epithelial counterparts. Although TGF beta 3 staining intensity was similar for both malignant and normal prostate epithelial cells, the pattern of staining switched from uniform apical to diffuse protein staining in malignant prostate glands.

CONCLUSIONS

Prostate cancer was associated with alterations of TGF beta 1, TGF beta 2, and TGF beta 3 expression by prostatic epithelial cells which may play a role in prostatic carcinogenesis.

Transforming growth factor-beta protects human hNT cells from degeneration induced by beta-amyloid peptide: involvement of the TGF-beta type II receptor

Post-mitotic, human neurons (hNT cells) which have a phenotype similar to that of terminally differentiated neurons of the central nervous system were generated by treating the NT2/D1 human teratocarcinoma cell line with retinoic acid. Treatment of both hNT and NT2/D1 cells with 10(-5) M beta-amyloid peptide fragment 25-35 (A beta P) for 24 h resulted in a decrease in cell viability as determined by MTT incorporation and Trypan blue exclusion, and also induced an apoptotic morphology in hNT cells. Pre-treatment of cells for 24 h with 10 ng/ml TGF-beta 1 or 2 before addition of A beta P reduced the apoptotic morphology of hNT cells and increased cell viability in hNT cells, but not in NT2/D1 cells. Results of RT-PCR, immunohistochemistry and analysis of receptor cross-linking of [125I]TGF-beta 1 to the cell membrane, all showed that the TGF-beta type II receptor is expressed by hNT cells, but not NT2/D1 cells. These results suggest that TGF-beta can protect human, terminally differentiated, TGF-beta type II receptor-positive neurons from A beta P toxicity. We propose that the increased expression of TGF-beta in brains of patients with Alzheimer's disease may offer some degree of neuroprotection if neurons also express a functional TGF-beta type II receptor.

Expression and regulation of transforming growth factor beta1 mRNA and protein in rat fetal testis in vitro

The expression and secretion of Transforming Growth Factor beta1 (TGFbeta1) by cultured testes of day 20.5 rat fetuses were investigated. The testes were found to express two TGFbeta1 mRNA transcripts of 2.5 and 1.8 kb. By using mink lung epithelial cell bioassay based on the measurement of the inhibition of tritiated thymidine incorporation in response to TGFbeta1 immunoreactive material, the fetal testes were shown to secrete TGFbeta1 protein in organ culture. This secretion was positively regulated by dibutyryl cyclic AMP or by LH and FSH together, but not by LH alone and very slightly by FSH alone, which suggests interactions between Leydig and Sertoli cells for the control of TGFbeta1 production. These regulations probably take place at a posttranscriptional step since no concomitant increase of TGFbeta1 mRNA levels was observed. Such a positive regulation of TGFbeta1 secretion by gonadotropins could be a characteristic of the rat fetal testis.