Differential regulation of a fibroblast growth factor-binding protein by receptor-selective analogs of retinoic acid

Expression of cellular retinoic acid-binding protein-I (CRABP-I) in the cerebrospinal fluid of adult onset moyamoya disease and its association with clinical presentation and postoperative haemodynamic change

OBJECTIVE

The elevation of cellular retinoic acid-binding protein-I (CRABP-I) has been suggested as a candidate in the pathogenesis of paediatric moyamoya disease (MMD). However, few studies have addressed CRABP-I in adult onset MMD. The aim of this study was to examine the expression of CRABP-I in the cerebrospinal fluid (CSF) of adult onset MMD, and to evaluate its association with clinical presentation and postoperative haemodynamic change.

METHODS

This study examined the CSF from 103 patients: bilateral MMD, n=58 (56.3%); unilateral MMD, n=19 (18.4%); atherosclerotic cerebrovascular disease (ACVD), n=21 (20.4%); and control group, n=5 (4.9%). The intensity of CRABP-I was confirmed by western blotting and expressed as the median (25th-75th percentile). The differences in CRABP-I expression according to disease entity (unilateral MMD vs bilateral MMD vs ACVD), initial presenting symptoms (haemorrhage vs ischaemia) and postoperative haemodynamic change (vascular reserve in single photon emission CT and basal collateral vessels in digital subtraction angiography) were analysed.

RESULTS

CRABP-I intensities in bilateral MMD (1.45(0.86-2.52)) were significantly higher than in unilateral MMD (0.91(0.78-1.20)) (p=0.044) or ACVD (0.85(0.66-1.11)) (p=0.004). No significant differences were noted based on the initial presenting symptoms (p=0.687). CRABP-I was not associated with improvement in vascular reserve (p=0.327), but with decrease in basal collateral vessels (p=0.023) postoperatively.

CONCLUSIONS

Higher CRABP-I in the CSF can be associated with typical bilateral MMD pathogenesis in adults. Additionally, postoperative basal collateral change may be related to the degree of CRABP-I expression.

Anti-tumor effects of fibroblast growth factor-binding protein (FGF-BP) knockdown in colon carcinoma

Background

Fibroblast growth factors FGF-1 and FGF-2 are often upregulated in tumors, but tightly bound to heparan sulphate proteoglycans of the extracellular matrix (ECM). One mechanism of their bioactivation relies on the FGF-binding protein (FGF-BP) which, upon reversible binding to FGF-1 or -2, leads to their release from the ECM. FGF-BP increases tumorigenicity and is highly expressed in tumors like colon carcinoma. In this paper, we analyse cellular and molecular consequences of RNAi-mediated FGF-BP knockdown in colon carcinoma, and explore the therapeutic effects of the nanoparticle-mediated delivery of small interfering RNAs (siRNAs) for FGF-BP targeting.

Results

Employing stable RNAi cells, we establish a dose-dependence of cell proliferation on FGF-BP expression levels. Decreased proliferation is mirrored by alterations in cell cycle distribution and upregulation of p21, which is relevant for mediating FGF-BP effects. While inhibition of proliferation is mainly associated with reduced Akt and increased GSK3β activation, antibody array-based analyses also reveal other alterations in MAPK signalling. Additionally, we demonstrate induction of apoptosis, mediated through caspase-3/7 activation, and alterations in redox status upon FGF-BP knockdown. These effects are based on the upregulation of Bad, Bax and HIF-1α, and the downregulation of catalase. In a therapeutic FGF-BP knockdown approach based on RNAi, we employ polymer-based nanoparticles for the in vivo delivery of siRNAs into established wildtype colon carcinoma xenografts. We show that the systemic treatment of mice leads to the inhibition of tumor growth based on FGF-BP knockdown.

Conclusions

FGF-BP is integrated in a complex network of cytoprotective effects, and represents a promising therapeutic target for RNAi-based knockdown approaches.

Retinoic acid inhibits angiogenesis and tumor growth of thyroid cancer cells

The anti-proliferative effect of retinoic acid (RA) has been documented for various tumors. Some 40% of patients with advanced and poorly differentiated thyroid cancer have been shown to respond to RA with increased uptake of radioiodine. It has been suggested that these effects may be caused by redifferentiation. Presently, little is known about the effects of RA on tumor angiogenesis, a prerequisite for growth and metastatic spread. The aim of the current study was to determine, whether tumor-induced angiogenesis of thyroid cancer is affected by RA. In vitro, the effect of 0.1/10 microM 13-cis RA on tumor cell number (MTT assay) and secretion of VEGF (ELISA) was analyzed in three thyroid cancer cell lines (FTC 236, C634 and XTC), as well as in endothelial cells (HUVEC) over several passages. In vivo, tumor growth, VEGF-expression and microvessel density (VSD) of RA treated thyroid cancer cells after xenotransplantation to nude mice was evaluated by morphometric analysis. In vitro, thyroid cancer cell lines responded to RA with reduced proliferation, ranging from 26 to 34% after 2 weeks of treatment and with up to 80% reduced secretion of VEGF. In vivo, tumor volumes of animals receiving RA were reduced by 33% (FTC 236), 27% (C643) and 6% (XTC), respectively. VSD of experimental tumors was diminished in the FTC 236 (25%) and the C643 cell line (15%), and almost unchanged in XTC tumors (7%). In vivo, VEGF-expression and apoptosis were not significantly affected by RA. In vitro, proliferation of HUVEC was inhibited by conditioned medium of C643 cells pretreated with RA (0.1/10 microM), as well as by administration of RA (0.1/10 microM). This study confirms thyroid tumor cell growth to be inhibited by RA. It demonstrates a decrease of in vitro VEGF accumulation and reduction of VSD in experimental undifferentiated thyroid carcinoma, suggesting that reduced angiogenesis may be an important mechanism responsible for the therapeutic effect of RA in thyroid cancer. Moreover, a direct anti-proliferative effect of RA on human endothelial cells is suggested.

The fibroblast growth factor-binding protein FGF-BP

Fibroblast growth factors (FGFs) are important regulators of cell migration, proliferation and differentiation, e.g., during embryogenesis and wound healing, and under several pathological conditions including tumor growth and tumor angiogenesis. Since heparin-binding FGFs are tightly bound to heparansulfate proteoglycans, and therefore, trapped in the extracellular matrix, their release through the action of an FGF-binding protein (FGF-BP) is one of the critical steps in FGF bioactivation. FGF-BP expression is highly tissue specific and strictly regulated through different promoter elements. Besides its role in embryogenesis and wound healing, FGF-BP is upregulated in several tumors and it is associated especially with early stages of tumor formation, where angiogenesis plays a critical role. Concomitantly, in several mouse tumor models, targeting of FGF-BP by ribozymes or RNA interference (RNAi) abolishes or reduces tumor growth and tumor angiogenesis. This indicates that FGF-BP can be rate-limiting for tumor growth and serves as an angiogenic switch molecule, and that it represents an increasingly promising target molecule in anti-tumor therapy.

Transforming growth factor-beta1 signaling participates in the physiological and pathological regulation of mouse inner ear development by all-trans retinoic acid

BACKGROUND

Retinoic acid (RA) is a vitamin A derivative that participates in patterning and regulation of inner ear development. Either excess RA or RA deficiency during a critical stage of inner ear development can produce teratogenic effects. Previous studies have shown that in utero exposure of the developing mouse inner ear to a high dose of all-trans RA (atRA) results in severe malformations of the inner ear that are associated with diminished levels of endogenous transforming growth factor-beta1 (TGF-beta(1)) protein.

METHODS

In this study, the effects of a teratogenic level of atRA on levels and patterns of expression of TGFbeta receptor II (TGFbetaRII) and Smad2, a downstream component of the TGFbeta signal transduction pathway, are investigated in the developing mouse inner ear. The expression pattern of endogenous RA receptor alpha (RARalpha) and the ability of an RARalpha(1)-specific antisense oligonucleotide (AS) to modulate otic capsule chondrogenesis are demonstrated in the inner ear and in culture.

RESULTS

Endogenous TGFbetaRII and Smad2 are downregulated in the inner ear following in utero atRA treatment. In addition, a reduction in endogenous TGFbeta(1) and a marked suppression of chondrogenesis occur in RARalpha(1) AS-treated cultures in comparison to untreated or oligonucleotide-treated control cultures. This chondrogenic suppression can be partially overcome by supplementation of RARalpha(1) AS-treated cultures with exogenous TGFbeta(1) protein.

CONCLUSIONS

Our findings support a role for TGFbeta in the physiological and pathological effects of RA on inner ear development.

Vascular leakage in chick embryos after expression of a secreted binding protein for fibroblast growth factors

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, beta-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.

Elevation of CRABP-I in the cerebrospinal fluid of patients with Moyamoya disease

BACKGROUND AND PURPOSE

The etiology of moyamoya disease (MMD) remains obscure. This study was undertaken to identify specific proteins associated with the pathogenesis of MMD.

METHODS

We studied cerebrospinal fluid (CSF) from 20 patients with angiographically confirmed MMD (4 boys and 16 girls; age range, 3 to 13 years; mean, 7.5 years) and 4 control patients with cerebral palsy who underwent selective dorsal rhizotomy (2 boys and 2 girls; age range, 5 to 10 years; mean, 7.3 years). CSF proteins were analyzed by 2-dimensional polyacrylamide gel electrophoresis, and protein identification was performed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presence of specific CSF protein in patients with MMD was confirmed by Western blotting. In addition, cerebral CSF was also tested in 7 patients who had other brain diseases but no MMD (2 boys and 5 girls; age range, 1 to 12 years; mean, 6.9 years).

RESULTS

We identified 1 polypeptide spot (Mr of 13 to 15 kDa and isoelectric point of 5 to 5.5) that was differentially expressed in the CSF samples of MMD patients (mean optical density intensity, 0.36+/-0.24; range, 0.05 to 0.92) and control spinal CSF samples (mean, 0.03+/-0.04; range, 0 to 0.08; P=0.002). This polypeptide was identified as cellular retinoic acid-binding protein (CRABP)-I. High levels of expression of CRABP-I in the CSF from 17 MMD children were confirmed by Western blotting.

CONCLUSIONS

The analysis of the CSF of MMD patients reveals high CRABP-I expression. The present study suggests that the elevation of CRABP-I in CSF may be a candidate for pathogenesis of MMD.

Isotretinoin treatment of acne in a patient with Apert syndrome

Apert syndrome is an autosomal dominant disease caused by mutations in fibroblast growth factor receptor (FGFR-2) and characterized by premature fusion of the cranial sutures and early epiphyseal closure. The development of widespread, severe, pustular acne around puberty is a characteristic feature in these patients. The FGFR-2 mutation of Apert syndrome has been described in localized nevoid acne lesions, which have been attributed to somatic mosaicism. Isotretinoin has been reported to be useful in controlling this acne. We report the successful treatment of acne with isotretinoin in a teenager with Apert syndrome and review the pathophysiology of acne in this syndrome.