The potential for chemical mixtures from the environment to enable the cancer hallmark of sustained proliferative signalling.

The aim of this work is to review current knowledge relating the established cancer hallmark, sustained cell proliferation to the existence of chemicals present as low dose mixtures in the environment. Normal cell proliferation is under tight control, i.e. cells respond to a signal to proliferate, and although most cells continue to proliferate into adult life, the multiplication ceases once the stimulatory signal disappears or if the cells are exposed to growth inhibitory signals. Under such circumstances, normal cells remain quiescent until they are stimulated to resume further proliferation. In contrast, tumour cells are unable to halt proliferation, either when subjected to growth inhibitory signals or in the absence of growth stimulatory signals. Environmental chemicals with carcinogenic potential may cause sustained cell proliferation by interfering with some cell proliferation control mechanisms committing cells to an indefinite proliferative span.

Insulin-like growth factor 2 in development and disease: a mini-review.

BACKGROUND: Insulin-like growth factor 2 (IGF2) is a protein hormone known to regulate cell proliferation, growth, migration, differentiation and survival. The gene is parentally imprinted in the sense that transcripts are almost exclusively derived from the paternal allele. Loss of imprinting of the IGF2 gene is a recurrent observation in growth disorders that combine overgrowth with a variety of malignant tumours. Moreover, IGF2 has been proposed to play a role in the development of a variety of seemingly unrelated cancers that play an important role in geriatric medicine, e.g., breast cancer, colon cancer and lung cancer. Finally, IGF2 has been implicated in cardiovascular disease, since, for example, IGF2 has been shown to influence the size of atherosclerotic lesions. OBJECTIVE: To summarize current knowledge about IGF2, its interactions with binding proteins and receptors and connections with key diseases. METHODS: The contents of this paper were based on reviews of existing literature within the field. RESULTS: There is a substantial amount of research linking IGF2 to growth disorders, cancer and to a much lesser degree cardiovascular disease. Some of the studies on IGF2 and tumour growth have yielded conflicting results, for instance regarding its effect on apoptosis. CONCLUSION: Today, our knowledge on how IGF2 is composed and interacts with receptors has come a long way. However, there is comparatively little information on how IGF2 affects tumour growth and cardiovascular diseases such as atherosclerosis. Thus, further research will be needed to elucidate the impact of IGF2 on key diseases.

Effects of fibroblast growth factors 19 and 20 on cell multiplication and locomotion in a human embryonal carcinoma cell line (Tera-2) in vitro.

BACKGROUND: The effects of two recently discovered heparin binding growth factors, FGF-19 and FGF-20, on the human embryonal carcinoma derived cell line Tera 2 were examined. MATERIALS AND METHODS: Cell numbers, as well as cell migration were examined at the clonal level by light microscopy. RESULTS: FGF-19, as well as FGF-20 promoted Tera 2 cell multiplication. Whereas FGF-20 promoted cell multiplication at low doses, FGF-19 was required at high doses to achieve a comparable effect. Moreover, FGF-19 did not significantly stimulate cell locomotion, while FGF-20 promoted cell motility at high doses. CONCLUSION: FGF-19 and FGF-20 qualitatively exert different effects on cell survival and cell locomotion.

Pathbase: a database of mutant mouse pathology.

Pathbase is a database that stores images of the abnormal histology associated with spontaneous and induced mutations of both embryonic and adult mice including those produced by transgenesis, targeted mutagenesis and chemical mutagenesis. Images of normal mouse histology and strain-dependent background lesions are also available. The database and the images are publicly accessible (http://www.pathbase.net) and linked by anatomical site, gene and other identifiers to relevant databases; there are also facilities for public comment and record annotation. The database is structured around a novel ontology of mouse disorders (MPATH) and provides high-resolution downloadable images of normal and diseased tissues that are searchable through orthogonal ontologies for pathology, developmental stage, anatomy and gene attributes (GO terms), together with controlled vocabularies for type of genetic manipulation or mutation, genotype and free text annotation for mouse strain and additional attributes. The database is actively curated and data records assessed by pathologists in the Pathbase Consortium before publication. The database interface is designed to have optimal browser and platform compatibility and to interact directly with other web-based mouse genetic resources.

The JNK interacting protein JIP-1 and insulin like growth factor II genes are co-expressed in human embryonic tumours.

JNK interacting protein 1 (JIP-1) is a pivotal scaffolding protein in the JNK signalling pathway. It is believed to play a role in the mediation of mitogenic messages from the plasma membrane to the cell interior. Recent evidence suggests that the JIP-1 gene is co-regulated with the insulin like growth factor II (IGF II) gene, thereby contributing to the growth-promoting effects of this potent growth factor. In this study, fourteen embryonic tumours were examined for the expression of JIP-1 and IGF II. It was found that, irrespective of histological type and expression level, the two genes showed a high degree of co-variation in the sense that high IGF II expression was followed by high expression of JIP-1. This finding further supports the notion that JIP-1 and IGF II act in concert to enhance cell proliferation.

Spider silk proteins--mechanical property and gene sequence.

Spiders spin up to seven different types of silk and each type possesses different mechanical properties. The reports on base sequences of spider silk protein genes have gained importance as the mechanical properties of silk fibers have been revealed. This review aims to link recent molecular data, often translated into amino acid sequences and predicted three dimensional structural motifs, to known mechanical properties.

Effects of fibroblast growth factor 8, fibroblast growth factor 9 and keratinocyte growth factor on multiplication and locomotion in human teratocarcinoma cells in vitro.

BACKGROUND: The effects of three members of the heparin binding growth factor family, FGF-8, FGF-9 and KGF, on the human embryonal carcinoma-derived cells line tera 2 were examined. MATERIALS AND METHODS: Cell numbers as well as cell migration was examined at clonal level by microscopy. RESULTS: It was found that each of these factors promoted Tera 2 cell multiplication, albeit with different efficacy. Whereas a dramatic effect on cell numbers was observed after the addition of 1-10 micrograms FGF-9/ml, a lesser effect could be achieved by FGF-8 or KGF. In contrast, KGF expressed the most potent effect on cell locomotion at a higher concentration (100 micrograms/ml). Even though high concentrations of FGF-8 and FGF-9 did stimulate cell locomotion, this effect was substantially smaller than that of KGF. CONCLUSION: All three FGFs exert a dual effect on Tera 2 cell survival and locomotion.

Expression of JNK interacting protein JIP-1 is down-regulated in liver from mouse embryos with a disrupted insulin-like growth factor II gene.

JNK interacting Protein 1 (JIP-1) is a pivotal scaffolding protein in the JNK signalling pathway. Its expression pattern in murine tissue indicates that JIP-1 has a role in the regulation of different cellular events. By examining the JIP-1 expression in transgenic mice that were heterozygous for a functional insulin-like growth factor II (igf-2) gene, it was possible to show that an abrogated igf-2 expression was followed by a decreased transcription of the JIP-1 gene. This pattern was consistent through different litters, which suggests that the up- or down-regulation of JIP-1 may well be part of the intracellular mediation of IGF II induced messages.

Pathbase: a new reference resource and database for laboratory mouse pathology.

Pathbase (http://www.pathbase.net) is a web accessible database of histopathological images of laboratory mice, developed as a resource for the coding and archiving of data derived from the analysis of mutant or genetically engineered mice and their background strains. The metadata for the images, which allows retrieval and interoperability with other databases, is derived from a series of orthogonal ontologies and controlled vocabularies. One of these controlled vocabularies, MPATH, was developed by the Pathbase Consortium as a formal description of the content of mouse histopathological images. The database currently has over 1000 images on-line with 2000 more under curation and presents a paradigm for the development of future databases dedicated to aspects of experimental biology.

The WT1 gene--its role in tumourigenesis and prospects for immunotherapeutic advances.

The Wilms Tumour 1 (WT1) gene is a complex gene which was originally linked to suppression of cancer in kidneys. Studies of WT1-knockout mice confirmed the important role of WT1 in the pathogenesis of Wilms' tumour, a tumour which accounts for 95% of all childhood renal tumours. In such cases, the WT1 gene acts as a tumour-suppressor gene. Subsequent research has shown that the WT1 gene in many other cases acts as an oncogene, most prominently in leukaemia and lung cancer (even though these cancer forms can emerge as a result of many other aetiological factors). Since WT1 acts as an oncogene in many different organs, it is of great importance to evaluate how and when the WT1 gene and protein act. This information can then be used to develop immunotherapy to stabilize and treat different malignant diseases. Both phase I and phase II studies have been carried out on candidate vaccines with varying but overall promising results. The immune response does not always correlate with the clinical response, however, and the efficacy of the treatment is often limited. Further development is, therefore, needed to understand how vaccines can be improved, so that they, can hopefully fulfil a clinical role in the future.

The RECK gene and biological malignancy--its significance in angiogenesis and inhibition of matrix metalloproteinases.

The RECK (reversion-inducing cysteine-rich protein with Kazal motifs) gene is a relatively newly discovered gene with important implications in cancer biology. RECK is normally expressed in all cells of the body and has an important role in the balance between destructive and constructive features of the extracellular matrix (ECM). The RECK protein is a membrane-bound glycoprotein that inhibits matrix metalloproteinases with the function of breaking-down the ECM. There is a significant correlation between RECK gene expression and the formation of new vessels, presumably via the mediation of vascular endothelial growth factor (VEGF), which is an important and powerful inducer of angiogenesis. Research has shown that down-regulation of RECK is caused by the rat sarcoma oncogene (RAS), which is also a common cause of tumor development in the early stages. For a tumor to progress and gain characteristics that classifies it as malignant, the degradation of the ECM and mobilization of new blood vessels are essential functions. If the tumor is inhibited with respect to these functions, it will cease to grow. RECK is, therefore, a potential tumor inhibitor but also a prognostic marker available at early clinical stages.

Review: The effect of insulin-like growth factor II in the regulation of tumour cell growth in vitro and tumourigenesis in vivo.

Insulin-like growth factor II (IGF-II) is a protein hormone that has been shown to exert several biological functions in mammals. IGF-II is produced mainly by the liver and to be systemically released to affect both the liver, in an autocrine and paracrine manner, as well as other tissues, through endocrine signaling. Nevertheless, it is also produced locally in various other tissues acting via autocrine and paracrine signalling. Research over the last decades has suggested that IGF-II also has a stimulatory effect on tumour cell growth but there are some notable exceptions to this rule. This conflicting view may have several explanations and hence current research has focused on gaining further insight into the transcriptional regulation and the metabolic pathways of IGF-II, which is hoped will result in greater understanding of the role of IGF-II in tumour development and new cancer therapies. This article aims at reviewing some of the key findings on how IGF-II affects tumour cells in vitro, as well as in vivo.

Effects of insulin-like growth factor binding protein 7 on apoptosis in human teratocarcinoma cells in vitro.

Human teratocarcinoma cells (Tera-2) deprived of serum undergo programmed cell death which can be counteracted by simultaneous addition of IGF-II. This protective effect of IGF-II was specific in the sense that addition of IGF-binding protein 7 (IGFBP-7) resulted in an increased apoptotic rate almost comparable to that of the classical IGFBPs. Autoradiographic analysis of incorporated tritiated thymidine indicated that the proportion of S-phase cells was comparable, irrespective of total cell numbers. This further suggests that IGF-II rescues cells from apoptosis and that IGFBP-7 is a specific antagonist.

The expression of the insulin-like growth factor II, JIP-1 and WT1 genes in porcine nephroblastoma.

c-Jun N-terminal kinase (JNK)-interacting protein 1 (JIP-1) is an important scaffolding protein in the JNK signalling pathway. It is also believed to play a role in the mediation of mitogenic messages from the plasma membrane to the cell interior. Previous studies have suggested that the JIP gene is co-regulated with the insulin-like growth factor II (IGF-II) gene, thereby contributing to the growth stimulatory effects of this potent growth factor. The striking co-expression of these two genes has been found in murine foetuses as well as in primary human embryonic tumours. When six primary Wilms tumours (nephroblastomas) from pig were examined, the two genes showed a high degree of co-variation in the sense that high or low expression of IGF-II and high or low expression of JIP-1 ocurred together. By contrast the expression of a third Wilms tumour-related gene, WT1, was completely uncorrelated to the expression of IGF-II and JIP. In this respect, porcine nephroblastomas resemble human Wilms tumours. This further suggests that JIP-1 may play a role in the regulation of IGF-II-driven tumour cell proliferation.

Expression of JNK-interacting protein JIP-1 and insulin-like growth factor II in Wilms tumour cell lines and primary Wilms tumours.

JNK-interacting protein 1 (JIP-1) is an important scaffolding protein in the JNK signalling pathway. It is also believed to play a role in the mediation of mitogenic messages from the plasma membrane to the cell interior. Previous studies suggest that the JIP-gene is co-regulated with the insulin-like growth factor II (IGF II) gene, thereby contributing to the growth stimulatory effects of this potent growth factor. The striking coexpression of these two genes was found in murine fetuses as well as in primary human embryonic tumours. When six primary Wilms tumours were examined, the two genes showed a high degree of co-variation in the sense that high expression of IGF II was followed by high expression of JIP-1 and vice versa. However, when the human Wilms tumour cell line WCCS-1 was examined, a very modest intrinsic expression of IGF II was accompanied by a moderate expression of JIP-1. When exogenous IGF II was added, which has previously been shown to induce apoptosis in this cell line, the JIP-1 expression increased. These data suggest that JIP-1 has a more complex role in the regulation of proliferation as well as programmed cell death.

Macroscopic fibers self-assembled from recombinant miniature spider silk proteins.

Strength, elasticity, and biocompatibility make spider silk an attractive resource for the production of artificial biomaterials. Spider silk proteins, spidroins, contain hundreds of repeated poly alanine/glycine-rich blocks and are difficult to produce recombinantly in soluble form. Most previous attempts to produce artificial spider silk fibers have included solubilization steps in nonphysiological solvents. It is here demonstrated that a miniature spidroin from a protein in dragline silk of Euprosthenops australis can be produced in a soluble form in Escherichia coli when fused to a highly soluble protein partner. Although this miniature spidroin contains only four poly alanine/glycine-rich blocks followed by a C-terminal non-repetitive domain, meter-long fibers are spontaneously formed after proteolytic release of the fusion partner. The structure of the fibers is similar to that of dragline silks, and although self-assembled from recombinant proteins they are as strong as fibers spun from redissolved silk. Moreover, the fibers appear to be biocompatible because human tissue culture cells can grow on and attach to the fibers. These findings enable controlled production of high-performance biofibers at large scale under physiological conditions.

N-terminal nonrepetitive domain common to dragline, flagelliform, and cylindriform spider silk proteins.

Spider silk has been extensively studied for its outstanding mechanical properties. Partial intermediate and C-terminal sequences of different spider silk proteins have been determined, and during the past decade also N-terminal domains have been characterized. However, only some of these N-terminal domains have been reported to contain signal peptides, leaving the mechanism whereby they enter the secretory pathway open to speculation. Here we present the sequence of a 394-residue N-terminal region of the Euprosthenops australis major ampullate spidroin 1 (MaSp1). A close comparison with published sequences from other species revealed the presence of N-terminal signal peptides followed by an approximately 130-residue nonrepetitive domain. From secondary structure predictions, helical wheel analysis, and circular dichroism spectroscopy this domain is concluded to contain five alpha-helices and is a conserved constituent of hitherto analyzed dragline, flagelliform, and cylindriform spider silk proteins.

Transient Expression of a Major Ampullate Spidroin 1 Gene Fragment from Euprosthenops sp. in Mammalian Cells.

Spider silk possesses extraordinary and unsurpassed mechanical properties and several attempts have been made to artificially produce spider silk in order to manufacture strong and light engineering composites. In the field of oncology, recombinant spider silk has the potential to be used as a biomaterial for bone replacement after tumour surgery. In this study, a 636-base pair gene fragment, coding for a part of major ampullate spidroin 1 from the African spider, Euprosthenops sp., was cloned into the expression vector pSecTag2/Hygro A, designed for the production of protein in mammalian cells. COS-1 cells were subsequently transfected with the recombinant plasmids and transient expression of low amounts of the corresponding silk protein fragment was obtained. The expressed fragment contained repetitive sequences associated with intrinsic biomechanical properties and has potential as a starting material for designed biopolymers.