Proteolysis-inducing factor (PIF), a novel cachectic factor, is detectable in the urine of cancer patients experiencing weight loss. We report the expression of PIF in gastrointestinal cancers, and a correlation between PIF expression in tumours, its detection in urine and weight-loss. These data provide the first direct evidence that tumours are the source of PIF in humans. © 2001 Cancer Research Campaign http://www.bjcancer.com

Germ line insertion of a human endogenous retroviruslike element (HERV-E.PTN) into the growth factor pleiotrophin (PTN) gene generated a phylogenetically new promoter driving the expression of functional HERV-PTN fusion transcripts. Here we show by in situ hybridization, that HERV-PTN fusion transcripts are expressed in malignant trophoblasts (i.e. choriocarcinoma) and in the proliferative and in the invasive trophoblasts of gestational trophoblastic tissue. Additionally, a 1.9 kb fragment of the HERV-derived PTN promoter was analysed which has strong activity when transiently transfected into choriocarcinoma JEG-3 cells in contrast to HeLa cells. Deletion of the retrovirallyderived promoter portion abolished its activity and an enhancer (+443 to +486) was identi®ed in this region. Electrophoretic mobility shift and supershift experiments identi®ed a Sp1 binding site in this enhancer and site speci®c mutation of this site abolished its activity in choriocarcinoma cells. Sp1 overexpression in Drosophila SL2 cells showed that the enhancer activity is mediated via Sp1 binding in vivo. Furthermore, mutation of the Sp1 binding site reduced the activity of a promoter test fragment in choriocarcinoma cells by 80%. Our result shows that a retroviral Sp1 binding site in the PTN promoter is important for the expression of growth factor pleiotrophin in human choriocarcinoma cells.

The initiation of premalignant lesions is associated with subtle cellular and gene expression changes. Here we describe a severe combined immunodeficiency mouse xenograft model with human adult skin and compare chemical carcinogenesis and wound healing. We focus on a secreted binding protein for fibroblast growth factors (FGF-BP) that enhances the activity of locally stored FGFs and is expressed at high levels in human epithelial cancers. Carcinogen treatment of murine skin induced papilloma within 6 weeks, whereas the human skin grafts displayed no obvious macroscopic alterations. Microscopic studies of the human skin, however, showed p53-positive keratinocytes in the epidermis, increased angiogenesis in the dermis of the treated skin, enhanced proliferation of keratinocytes in the basal layer, and an increase of FGF-BP protein and mRNA expression. In contrast, after surgical wounding of human skin grafts or of mouse skin, FGF-BP expression was upregulated within a few hours and returned to control levels after 2 days with wound closure. Enhanced motility of cultured keratinocytes and dermal fibroblasts by FGF-BP supports a role in wound healing. We conclude that adult human skin xenografts can be used to identify early molecular events during malignant transformation as well as transient changes during wound healing.

The fibroblast growth factor binding protein (FGF-BP; GenBank accession no. NP_005121) is a secreted protein that mobilizes FGFs from the extracellular matrix, protects them from degradation, and enhances their biological activity. Several previous studies reported that FGF-BP is an early response gene upregulated during tissue repair processes including wound healing and atherogenesis. In this study we analyzed whether FGF-BP expression was impacted by spinal cord injury and could have an effect on neuronal cell viability. Immunohistochemical and in situ hybridization studies revealed a dramatic upregulation of FGF-BP protein and mRNA levels following unilateral hemisection and contusion injury of adult rat spinal cord. In spinal cord sections of laminectomized rats, increased FGF-BP expression was observed in the fibers and cell bodies ipsilateral to the lesion site but was absent in the uninjured spinal cord tissue contralateral to the lesion. Increased expression of FGF-BP was observed at all postinjury time points, examined with peak levels occurring at day 4, a time when injury-induced increased levels of FGF2 have also been reported to be maximal. Moreover, using PC12 cells as a neuronal model, we observed that exogenous FGF-BP increased the capacity of FGF2 to stimulate neurite outgrowth and to increase cell survival. At the molecular level, FGF-BP enhanced FGF2-induced protein tyrosine phosphorylation and AKT/PKB activation. Collectively, these results suggest that FGF-BP is an early response gene after spinal cord injury and that its upregulation in regenerating spinal cord tissue may provide a molecular mechanism for enhancing the initial FGF2-mediated neurotrophic effects occurring after such tissue damage.

Fibroblast growth factors (FGFs) have been implicated in a variety of physiologic and pathologic processes from embryonic development to tumor growth and angiogenesis. FGFs are immobilized in the extracellular matrix of different tissues and require release from this storage site to trigger a response. Secreted FGF-binding proteins (FGF-BPs) can release immobilized FGFs, enhance the activity of locally stored FGFs and can thus serve as an angiogenic switch molecule in cancer. Here, we report on the effect of human FGF-BP transgene expression in chicken embryos. To establish the transgenic model, plasmid-based reporter vectors expressing luciferase, b-galactosidase or green fluorescent protein were introduced through different routes into 4-to 5-day-old embryos grown outside their egg shell on top of the yolk sac. This allows for easy manipulation and continuous observation of phenotypic effects. Expression of human FGF-BP induced dose-dependent vascular permeability, hemorrhage and embryonic lethality. Light and electron microscopic studies indicate that this hemorrhage results from compromised microvascular structure. An FGF-1 expression vector with an added secretory signal mimicked this vascular leakiness phenotype whereas wild-type FGF-1 required coexpression of a threshold amount of FGF-BP. This model is a powerful tool for real-time monitoring of the effects of transient transgene expression during embryogenesis.