Blocks Fibroblast Growth Factor Research Articles

Thyroid Hormones Regulate Goblet Cell Differentiation and Fgf19-Fgfr4 Signaling.

Hypothyroidism is a common pathological condition characterized by insufficient activity of the thyroid hormones (THs), thyroxine (T4), and 3,5,3'-triiodothyronine (T3), in the whole body or in specific tissues. Hypothyroidism is associated with inadequate development of the intestine as well as gastrointestinal diseases. We used a zebrafish model of hypothyroidism to identify and characterize TH-modulated genes and cellular pathways controlling intestine development. In the intestine of hypothyroid juveniles and adults, the number of mucus-secreting goblet cells was reduced, and this phenotype could be rescued by T3 treatment. Transcriptome profiling revealed dozens of differentially expressed genes in the intestine of hypothyroid adults compared to controls. Notably, the expression of genes encoding to Fgf19 and its receptor Fgfr4 was markedly increased in the intestine of hypothyroid adults, and treatment with T3 normalized it. Blocking fibroblast growth factor (FGF) signaling, using an inducible dominant-negative Fgfr transgenic line, rescued the number of goblet cells in hypothyroid adults. These results show that THs inhibit the Fgf19-Fgfr4 signaling pathway, which is associated with inhibition of goblet cell differentiation in hypothyroidism. Both the TH and Fgf19-Fgfr4 signaling pathways can be pharmaceutical targets for the treatment of TH-related gastrointestinal diseases.

A novel monovalent FGFR1 antagonist: Preclinical safety profiles in rodents and non-human primates

Blocking Fibroblast Growth Factor Receptor 1 (FGFR1) is an attractive therapeutic option for treatment of cancer subtypes with amplification and over-expression of FGFR1. Selective targeting of FGFR1 can be achieved using an antibody-based approach, as small molecule inhibitors may not discriminate between FGFR1, 2, 3 and 4 due to their highly homologous kinase domain. However, development of classical bivalent FGFR1 directed antibodies has failed due to non-tolerated body weight decreases in preclinical species. M6123 is a novel IgG-like monovalent FGFR1 specific binder with enhanced Antibody-Dependent Cellular Cytotoxicity (ADCC) effector function and inhibits tumor growth significantly in FGFR1-dependent human xenograft models without reduced body weight in tumor-bearing mice. Toxicology studies reported here characterized the safety profile of M6123 in mouse, rat, and monkey. There were significant differences among animal species under similar M6123 exposure levels. Rats showed metastatic mineralization with an imbalance in serum phosphate at low doses, while mineralization was not found in mice or monkeys, even though hyperphosphatemia was detected in mice. Subtle differences in calcium/phosphate homoeostasis feedback loops may trigger the susceptibility to mineralization among animal species; nevertheless, the exact mechanism remains unknown. Monkeys showed marked, but reversible, decreases in peripheral blood NK cells and neutrophils. The latter was associated with considerably increased neutrophilic infiltrates in the liver sinusoids and red pulp of the spleen. These effects in monkeys are likely related to the enhanced ADCC activity of M6123. Overall, M6123 showed a superior safety profile in animals compared to bivalent FGFR1 antagonists or pan-FGFR inhibitors.

Anti-Proliferative Role of the Tyrosine Kinase Inhibitors TKI-258 on Oral Squamous Cell Carcinoma In Vitro.

Identification of the antitumor role of tyrosine kinase inhibitors, such as TKI-258, may lead to novel therapeutics for Oral Squamous Cell Carcinoma (OSCC), which has high mortality rates. TKI-258 blocks Fibroblast Growth Factor Receptors (FGFRs), Platelet-Derived Growth Factor Receptors (PDGFRs), and Endothelial Growth Factor Receptor (VEGFRs). This study aimed to evaluate the effect of TKI-258 treatment on cell proliferation in SCC-4 cells of OSCC. BrdU and KI-67 assays were performed by using SCC-4 cells. Control was compared to 1, 5 and 10μM TKI-258 treatment. Control vehicle was compared to: 60μM LY294002 (LY), 2μM Wortmannin (WTN) and LY+WNT. Moreover, TKI 5μM treatment was compared to: TKI 5μM+LY; TKI 5 μM+WTN; TKI 5μM+LY+WTN. After 6h of treatments, immunofluorescence stained BrdU and KI-67 positive cells. Morphometry of proliferative cells was analyzed considering significance of p<0.05. BrdU and KI-67 assays results were similar for all experiments. TKI-258 treatment leads to an important reduction in proliferation rate in SCC-4 cells in a concentration dependent manner. As expected, there was a significant reduction in the percentage of proliferative cells that had PI3K inhibited. When compared with TKI 5 treatment, proliferating cells were significantly lower with simultaneous PI3K inhibition. This study demonstrated that TKI-258 plays an anti-proliferative role on SCC-4 cells of OSCC. It could be interesting to block multiples pathways such as FGFRs, PDGFRs and VEGFRs. Therefore, TKI-258 is a promising option for novel therapeutics for OSCC, especially if associated with PI3K inhibition.

MAPK inhibition and growth hormone: a promising therapy in XLH.

X-linked hypophosphatemia (XLH) leads to growth retardation and bone deformities, which are not fully avoided by conventional treatment with phosphate and vitamin D analogs. Pediatric patients have been treated with growth hormone (GH), and recent findings suggest that blocking fibroblast growth factor 23 actions may be the most effective therapy, but its effects on growth are not known. We here report the effect of MAPK inhibition alone or associated with GH on growth and growth plate and bone structure of young Hyp (the XLH animal model) mice. Untreated Hyp mice were severely growth retarded and had marked alterations in both growth plate structure and dynamics as well as defective bone mineralization. GH accelerated growth and improved mineralization and the cortical bone, but it failed in normalizing growth plate and trabecular bone structures. MAPK inhibition improved growth and rickets and, notably, almost normalized the growth plate organization. The administration of a MAPK pathway inhibitor plus GH was the most beneficial treatment because of the positive synergistic effect on growth plate and bone structures. Thus, the growth-promoting effect of GH is likely linked to increased risk of bone deformities, whereas the association of GH and MAPK inhibition emerges as a promising new therapy for children with XLH.-Fuente, R., Gil-Peña, H., Claramunt-Taberner, D., Hernández-Frías, O., Fernández-Iglesias, Á., Alonso-Durán, L., Rodríguez-Rubio, E., Hermida-Prado, F., Anes-González, G., Rubio-Aliaga, I., Wagner, C., Santos, F. MAPK inhibition and growth hormone: a promising therapy in XLH.

Melanoma Cell Adhesion and Migration Is Modulated by the Uronyl 2-O Sulfotransferase.

Although the vast majority of melanomas are characterized by a high metastatic potential, if detected early, melanoma can have a good prognostic outcome. However, once metastasised, the prognosis is bleak. We showed previously that uronyl-2-O sulfotransferase (Ust) and 2-O sulfation of chondroitin/dermatan sulfate (CS/DS) are involved in cell migration. To demonstrate an impact of 2-O sulfation in metastasis we knocked-down Ust in mouse melanoma cells. This significantly reduced the amount of Ust protein and enzyme activity. Furthermore, in vitro cell motility and adhesion were significantly reduced correlating with the decrease of cellular Ust protein. Single cell migration of B16VshUst(16) cells showed a decreased cell movement phenotype. The adhesion of B16V cells to fibronectin depended on α5β1 but not αvβ3 integrin. Inhibition of glycosaminoglycan sulfation or blocking fibroblast growth factor receptor (FgfR) reduced α5 integrin in B16V cell lines. Interestingly, FgfR1 expression and activation was reduced in Ust knock-down cells. In vivo, pulmonary metastasis of B16VshUst cells was prevented due to a reduction of α5 integrin. As a proof of concept UST knock-down in human melanoma cells also showed a reduction in ITGa5 and adhesion. This is the first study showing that Ust, and consequently 2-O sulfation of the low affinity receptor for FgfR CS/DS, reduces Itga5 and leads to an impaired adhesion and migration of melanoma cells.

SCN5A variant that blocks fibroblast growth factor homologous factor regulation causes human arrhythmia

Nav channels are essential for metazoan membrane depolarization, and Nav channel dysfunction is directly linked with epilepsy, ataxia, pain, arrhythmia, myotonia, and irritable bowel syndrome. Human Nav channelopathies are primarily caused by variants that directly affect Nav channel permeability or gating. However, a new class of human Nav channelopathies has emerged based on channel variants that alter regulation by intracellular signaling or cytoskeletal proteins. Fibroblast growth factor homologous factors (FHFs) are a family of intracellular signaling proteins linked with Nav channel regulation in neurons and myocytes. However, to date, there is surprisingly little evidence linking Nav channel gene variants with FHFs and human disease. Here, we provide, to our knowledge, the first evidence that mutations in SCN5A (encodes primary cardiac Nav channel Nav1.5) that alter FHF binding result in human cardiovascular disease. We describe a five*generation kindred with a history of atrial and ventricular arrhythmias, cardiac arrest, and sudden cardiac death. Affected family members harbor a novel SCN5A variant resulting in p.H1849R. p.H1849R is localized in the central binding core on Nav1.5 for FHFs. Consistent with these data, Nav1.5 p.H1849R affected interaction with FHFs. Further, electrophysiological analysis identified Nav1.5 p.H1849R as a gain-of-function for INa by altering steady-state inactivation and slowing the rate of Nav1.5 inactivation. In line with these data and consistent with human cardiac phenotypes, myocytes expressing Nav1.5 p.H1849R displayed prolonged action potential duration and arrhythmogenic afterdepolarizations. Together, these findings identify a previously unexplored mechanism for human Nav channelopathy based on altered Nav1.5 association with FHF proteins.

Involvement of Hedgehog and FGF signalling in the lamprey telencephalon: evolution of regionalization and dorsoventral patterning of the vertebrate forebrain

Dorsoventral (DV) specification is a crucial step for the development of the vertebrate telencephalon. Clarifying the origin of this mechanism will lead to a better understanding of vertebrate central nervous system (CNS) evolution. Based on the lamprey, a sister group of the gnathostomes (jawed vertebrates), we identified three lamprey Hedgehog (Hh) homologues, which are thought to play central signalling roles in telencephalon patterning. However, unlike in gnathostomes, none of these genes, nor Lhx6/7/8, a marker for the migrating interneuron subtype, was expressed in the ventral telencephalon, consistent with the reported absence of the medial ganglionic eminence (MGE) in this animal. Homologues of Gsh2, Isl1/2 and Sp8, which are involved in the patterning of the lateral ganglionic eminence (LGE) of gnathostomes, were expressed in the lamprey subpallium, as in gnathostomes. Hh signalling is necessary for induction of the subpallium identity in the gnathostome telencephalon. When Hh signalling was inhibited, the ventral identity was disrupted in the lamprey, suggesting that prechordal mesoderm-derived Hh signalling might be involved in the DV patterning of the telencephalon. By blocking fibroblast growth factor (FGF) signalling, the ventral telencephalon was suppressed in the lamprey, as in gnathostomes. We conclude that Hh- and FGF-dependent DV patterning, together with the resultant LGE identity, are likely to have been established in a common ancestor before the divergence of cyclostomes and gnathostomes. Later, gnathostomes would have acquired a novel Hh expression domain corresponding to the MGE, leading to the obtainment of cortical interneurons.

Adenovirus-mediated expression of dominant negative fibroblast growth factor (FGF) receptor 1 in thyroid cells blocks FGF effects and reduces goitrogenesis in mice.

Levels of fibroblast growth factor 2 (FGF-2) and its receptor, FGFR1, are elevated in goiter, but whether this is a direct effect of TSH is unknown. We have determined the regulation of FGF-2 and FGFR1 synthesis by TSH in a rat thyroid cell line (FRTL5) and have used a replication-defective adenovirus (RAd) expressing dominant negative FGFR1 (RAdDN-FGFR1) to examine the role of FGFR signaling in vitro and in goiter induced in mice. TSH induced FGF-2 and increased the expression of FGFR1 in FRTL5 cells. Infection of TSH-stimulated FRTL5 cells with RAdDN-FGFR1 inhibited growth and prevented FGF-2-mediated inhibition of (125)I uptake. Similar effects were found in primary cultures of human thyroid follicular cells. For in vivo experiments, male BALB/c mice were injected systemically with RAdDN-FGFR1 or RAd encoding green fluorescent protein, and goiter was simultaneously induced. Mouse thyroid follicles were shown to be transduced with RAd encoding green fluorescent protein. Circulating TSH was elevated comparably in the two groups. In the RAdDN-FGFR1-injected animals, goiter induced over 14 d was significantly smaller, and the vascular volume increase seen in goiter was also diminished. We conclude that the FGF axis is important in thyroid growth and that RAdDN-FGFR1 effectively blocks FGF actions, offering a means to control goitrogenesis.

The SH2-containing protein-tyrosine phosphatase SH-PTP2 is required upstream of MAP kinase for early xenopus development

SH-PTP2, the vertebrate homolog of Drosophila corkscrew, associates with several activated growth factor receptors, but its biological function is unknown. We assayed the effects of injection of wild-type and mutant SH-PTP2 RNAs on Xenopus embryogenesis. An internal phosphatase domain deletion (ΔP) acts as a dominant negative mutant, causing severe posterior truncations. This phenotype is rescued by SH-PTP2, but not by the closely related SH-PTP1. In ectodermal explants, ΔP blocks fibroblast growth factor (FGF)- and activin-mediated induction of mesoderm and FGF-induced mitogen-activated protein (MAP) kinase activation. Our results indicate that SH-PTP2 is required for early vertebrate development, acting as a positive component in FGF signaling downstream of the FGF receptor and upstream of MAP kinase.