Activation Of Fibroblast Growth Factor Receptor Research Articles

Low-Dose Infigratinib Increases Bone Growth And Corrects Growth Plate Abnormalities In An Achondroplasia Mouse Model.

Achondroplasia, the most common form of disproportionate short stature, is caused by gain-of-function point mutations in fibroblast growth factor receptor 3 (FGFR3). Abnormally elevated activation of FGFR3 modulates chondrocyte proliferation and differentiation via multiple signaling pathways, such as the MAPK pathway. Using a mouse model mimicking achondroplasia (Fgfr3Y367C/+), we have previously shown that daily treatment with infigratinib (BGJ398), a selective and orally bioavailable FGFR1-3 inhibitor, at a dose of 2 mg/kg, significantly increased bone growth. In this study, we investigated the activity of infigratinib administered at substantially lower doses (0.2 and 0.5 mg/kg, given once daily) and using an intermittent dosing regimen (1 mg/kg every 3 days). Following a 15-day treatment period, these low dosages were sufficient to observe significant improvement of clinical hallmarks of achondroplasia such as growth of the axial and appendicular skeleton and skull development. Immunohistological labeling demonstrated the positive impact of infigratinib on chondrocyte differentiation in the cartilage growth plate and the cartilage end plate of the vertebrae. Macroscopic and microcomputed analyses showed enlargement of the foramen magnum area at the skull base, thus improving foramen magnum stenosis, a well-recognized complication in achondroplasia. No changes in FGF23 or phosphorus levels were observed, indicating that the treatment did not modify phosphate homeostasis. This proof-of-concept study demonstrates that infigratinib administered at low doses has the potential to be a safe and effective therapeutic option for children with achondroplasia.

Abstract A165: FGFR alterations in pediatric cancers: Opportunity for targeted therapy

Abstract Introduction: The Fibroblast Growth Factor Receptor (FGFR) family consists of four members, FGFR1–4, and is involved in regulating cell proliferation, survival, and differentiation. FGFR alterations, such as fusions, mutations and amplification, have been found in multiple adult cancers, for which several FGFR inhibitors are in clinical development. Although cancer is a leading cause of death in children, the understanding of genetic causes of pediatric cancers is urgently lacking and the progress in developing targeted therapy in children significantly lags that in adults. This study aimed to uncover the FGFR alterations in pediatric cancers and provide preclinical rationale for FGFR inhibitors as potential therapy in children with cancer.  Methods: The prevalence of FGFR alterations in pediatric cancers such as neuroblastoma (NB) , gliomas and sarcomas was calculated based on systematic queries of multiple cancer databases that house real-world molecular profiling data. A pan-FGFR inhibitor, BGJ398, was used as a tool compound for FGFR inhibition. Effect of BGJ398 on cell proliferation was tested by Incucyte in a panel of 12 NB cell lines. Cell migration, survival and signaling pathway modulation were carried out in a subset of NB lines. Results: The overall rates of genomic alterations (fusions, mutations and amplification) of FGFR1, 2, 3 and 4 in pediatric cancers are 0.5%, 0.1%, 1.1% and 0.8%, respectively, with pediatric gliomas exhibiting higher rates in all subtypes. Although FGFR genomic alterations are rare (<0.1%) in neuroblastoma and rhabdoid sarcoma, overexpression of FGFR1-4 is observed in subsets of these tumors. In pediatric glioma, FGFR1, 2, 3 and 4 alterations are found in 1%, 1.6%, 2.1% and 0.9% tumor samples, respectively, and the mutation profile substantially differs from that of adult glioma. Dose-dependent inhibition of cell proliferation and migration, as well as induction of cell death, were achieved with BGJ398 treatment in a panel of NB cells, accompanied by inhibition of MAPK pathway and induction of apoptosis. Conclusions: Adult and pediatric cancers share common mechanisms of FGFR activation, but differ in overall alteration rates and in relative abundance of specific aberrations. Preliminary preclinical data indicates the therapeutic potential of FGFR inhibitors in the treatment of certain pediatric cancers. Citation Format: Ivan Li, Yuchen Huo, Gary Li, Peter Zage. FGFR alterations in pediatric cancers: Opportunity for targeted therapy [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A165.

Oncostatin M enhances osteoprotegerin synthesis but reduces macrophage colony‑stimulating factor synthesis in bFGF‑stimulated osteoblast‑like cells.

Bone remodeling is tightly controlled by various factors, including hormones, autacoids and cytokines. Among them, oncostatin M (OSM) is a multifunctional cytokine produced by osteal macrophages, which serves as an essential modulator of bone remodeling. Macrophage colony-stimulating factor (M-CSF) and osteoprotegerin are secreted by osteoblasts, and also have pivotal roles in the regulation of the bone remodeling process. The binding of basic fibroblast growth factor (bFGF), a key regulator of bone remodeling, to the corresponding receptor [fibroblast growth factor receptor (FGFR)] triggers the dimerization and activation of FGFRs, which causes the phosphorylation of FGFR substrates and subsequent activation of downstream effectors, including mitogen-activated protein kinases (MAPKs), via Grb2. bFGF can activate MAPKs, resulting in the synthesis of osteoprotegerin and vascular endothelial growth factor in osteoblast-like MC3T3-E1 cells. In the present study, the effects of OSM on bFGF-induced osteoblast activation were investigated in the synthesis of osteoprotegerin and M-CSF in osteoblasts. The release of osteoprotegerin and M-CSF were analyzed using ELISA. The mRNA expression levels of osteoprotegerin and M-CSF were analyzed using reverse transcription-quantitative PCR. Phosphorylation of p38 MAPK, stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) and p44/p42 MAPK was assessed using western blotting. OSM enhanced bFGF-induced osteoprotegerin release and bFGF-stimulated mRNA expression of osteoprotegerin. By contrast, OSM suppressed the bFGF-induced release of M-CSF and bFGF-stimulated mRNA expression of M-CSF. SB203580, a p38 MAPK inhibitor, and SP600125, a SAPK/JNK inhibitor, suppressed the bFGF-stimulated M-CSF release, whereas PD98059, an upstream kinase inhibitor of p44/p42 MAPK, failed to suppress the M-CSF release stimulated by bFGF. Furthermore, OSM enhanced the bFGF-induced phosphorylation of p38 MAPK, but attenuated the bFGF-stimulated phosphorylation of SAPK/JNK. By contrast, OSM had little effect on the bFGF-induced phosphorylation of p44/p42 MAPK. SB203580 markedly reduced the amplification of bFGF-stimulated osteoprotegerin release enhanced by OSM. These results strongly suggested that OSM may possess divergent effects on bFGF-induced osteoblast activation, upregulation of p38 MAPK and downregulation of SAPK/JNK, leading to the amplification of osteoprotegerin synthesis and the attenuation of M-CSF synthesis.

Cell-based screen identifies porphyrins as FGFR3 activity inhibitors with therapeutic potential for achondroplasia and cancer.

Overactive fibroblast growth factor receptor 3 (FGFR3) signaling drives pathogenesis in a variety of cancers and a spectrum of short-limbed bone dysplasias, including the most common form of human dwarfism, achondroplasia (ACH). Targeting FGFR3 activity holds great promise as a therapeutic approach for treatment of these diseases. Here, we established a receptor/adaptor translocation assay system that can specifically monitor FGFR3 activation, and we applied it to identify FGFR3 modulators from complex natural mixtures. An FGFR3-suppressing plant extract of Amaranthus viridis was identified from the screen, and 2 bioactive porphyrins, pheophorbide a (Pa) and pyropheophorbide a, were sequentially isolated from the extract and functionally characterized. Further analysis showed that Pa reduced excessive FGFR3 signaling by decreasing its half-life in FGFR3-overactivated multiple myeloma cells and chondrocytes. In an ex vivo culture system, Pa alleviated defective long bone growth in humanized ACH mice (FGFR3ACH mice). Overall, our study presents an approach to discovery and validation of plant extracts or drug candidates that target FGFR3 activation. The compounds identified by this approach may have applications as therapeutics for FGFR3-associated cancers and skeletal dysplasias.

The Comparison of Commercial Serum-Free Media for Hanwoo Satellite Cell Proliferation and the Role of Fibroblast Growth Factor 2.

Fetal bovine serum (FBS), which contains various nutrients, comprises 20% of the growth medium for cell-cultivated meat. However, ethical, cost, and scientific issues, necesitates identification of alternatives. In this study, we investigated commercially manufactured serum-free media capable of culturing Hanwoo satellite cells (HWSCs) to identify constituent proliferation enhancing factors. Six different serum-free media were selected, and the HWSC proliferation rates in these serum-free media were compared with that of control medium supplemented with 20% FBS. Among the six media, cell proliferation rates were higher only in StemFlexTM Medium (SF) and Mesenchymal Stem Cell Growth Medium DXF (MS) than in the control medium. SF and MS contain high fibroblast growth factor 2 (FGF2) concentrations, and we found upregulated FGF2 protein expression in cells cultured in SF or MS. Activation of the fibroblast growth factor receptor 1 (FGFR1)-mediated signaling pathway and stimulation of muscle satellite cell proliferation-related factors were confirmed by the presence of related biomarkers (FGFR1, FRS2, Raf1, ERK, p38, Pax7, and MyoD) as indicated by quantitative polymerase chain reaction, western blotting, and immunocytochemistry. Moreover, PD173074, an FGFR1 inhibitor suppressed cell proliferation in SF and MS and downregulated related biomarkers (FGFR1, FRS2, Raf1, and ERK). The promotion of cell proliferation in SF and MS was therefore attributed to FGF2, which indicates that FGFR1 activation in muscle satellite cells may be a target for improving the efficiency of cell-cultivated meat production.

Embryonic cranial cartilage defects in the Fgfr3Y367C /+ mouse model of achondroplasia.

Achondroplasia, the most common chondrodysplasia in humans, is caused by one of two gain of function mutations localized in the transmembrane domain of fibroblast growth factor receptor 3 (FGFR3) leading to constitutive activation of FGFR3 and subsequent growth plate cartilage and bone defects. Phenotypic features of achondroplasia include macrocephaly with frontal bossing, midface hypoplasia, disproportionate shortening of the extremities, brachydactyly with trident configuration of the hand, and bowed legs. The condition is defined primarily on postnatal effects on bone and cartilage, and embryonic development of tissues in affected individuals is not well studied. Using the Fgfr3Y367C/+ mouse model of achondroplasia, we investigated the developing chondrocranium and Meckel's cartilage (MC) at embryonic days (E)14.5 and E16.5. Sparse hand annotations of chondrocranial and MC cartilages visualized in phosphotungstic acid enhanced three-dimensional (3D) micro-computed tomography (microCT) images were used to train our automatic deep learning-based 3D segmentation model and produce 3D isosurfaces of the chondrocranium and MC. Using 3D coordinates of landmarks measured on the 3D isosurfaces, we quantified differences in the chondrocranium and MC of Fgfr3Y367C/+ mice relative to those of their unaffected littermates. Statistically significant differences in morphology and growth of the chondrocranium and MC were found, indicating direct effects of this Fgfr3 mutation on embryonic cranial and pharyngeal cartilages, which in turn can secondarily affect cranial dermal bone development. Our results support the suggestion that early therapeutic intervention during cartilage formation may lessen the effects of this condition.

Knockdown of PTK7 Reduces the Oncogenic Potential of Breast Cancer Cells by Impeding Receptor Tyrosine Kinase Signaling.

Protein tyrosine kinase 7 (PTK7), a catalytically defective receptor tyrosine kinase (RTK), is often upregulated in various cancers. This study aimed to validate PTK7 as a target for breast cancer (BC) and investigate its oncogenic signaling mechanism. BC tissue analysis showed significantly elevated PTK7 mRNA levels, especially in refractory triple-negative breast cancer (TNBC) tissues, compared with normal controls. Similarly, BC cell lines exhibited increased PTK7 expression. Knockdown of PTK7 inhibited the proliferation of T-47D and MCF-7 hormone-receptor-positive BC cell-lines and of HCC1187, MDA-MB-231, MDA-MB-436, and MDA-MB-453 TNBC cells. PTK7 knockdown also inhibited the adhesion, migration, and invasion of MDA-MB-231, MDA-MB-436, and MDA-MB-453 cells, and reduced the phosphorylation levels of crucial oncogenic regulators including extracellular signal-regulated kinase (ERK), Akt, and focal adhesion kinase (FAK). Furthermore, PTK7 interacts with fibroblast growth factor receptor 1 (FGFR1) and epidermal growth factor receptor (EGFR) expressed in MDA-MB-231 cells. Knockdown of PTK7 decreased the growth-factor-induced phosphorylation of FGFR1 and EGFR in MDA-MB-231 cells, indicating its association with RTK activation. In conclusion, PTK7 plays a significant role in oncogenic signal transduction by enhancing FGFR1 and EGFR activation, influencing BC tumorigenesis and metastasis. Hence, PTK7 represents a potential candidate for targeted BC therapy, including TNBC.

Hypochondroplasia gain-of-function mutation in FGFR3 causes defective bone mineralization in mice.

Hypochondroplasia (HCH) is a mild dwarfism caused by missense mutations in fibroblast growth factor receptor 3 (FGFR3), with the majority of cases resulting from a heterozygous p.Asn540Lys gain-of-function mutation. Here, we report the generation and characterization of the first mouse model (Fgfr3Asn534Lys/+) of HCH to our knowledge. Fgfr3Asn534Lys/+ mice exhibited progressive dwarfism and impairment of the synchondroses of the cranial base, resulting in defective formation of the foramen magnum. The appendicular and axial skeletons were both severely affected and we demonstrated an important role of FGFR3 in regulation of cortical and trabecular bone structure. Trabecular bone mineral density (BMD) of long bones and vertebral bodies was decreased, but cortical BMD increased with age in both tibiae and femurs. These results demonstrate that bones in Fgfr3Asn534Lys/+ mice, due to FGFR3 activation, exhibit some characteristics of osteoporosis. The present findings emphasize the detrimental effect of gain-of-function mutations in the Fgfr3 gene on long bone modeling during both developmental and aging processes, with potential implications for the management of elderly patients with hypochondroplasia and osteoporosis.

1527-P: Anorexia Induced by the Central Action of Fibroblast Growth Factor 1 (FGF1) Is Dependent on Reduced GABA Receptor Activation

Previously, we reported that in multiple rodent models of type 2 diabetes, remission of hyperglycemia lasting for weeks can be induced by a single intracerebroventricular (icv) injection of FGF1. This effect is accompanied by a potent but transient anorexic response that is sufficiently robust as to hinder efforts to translate these findings towards the clinic. To understand the mechanism underlying FGF1-induced anorexia, we considered 1) our recent finding that icv FGF1 induces acute and sustained inhibition of hypothalamic AgRP neurons, and 2) prior work showing that parabrachial nucleus that express calcitonin gene-related peptide (PBNCGRP neurons) are both highly anorexigenic and tonically inhibited by GABAergic projections from AgRP neurons. We therefore hypothesized that FGF1-induced anorexia involves activation PBNCGRPneurons arising from reduced GABAergic input. Consistent with this hypothesis, we report that PBNCGRPneurons are robustly activated following icv FGF1 injection (based on c-Fos staining) via a mechanism that appears to be indirect, since the c-Fos induction is not associated with FGF receptor (FGFR) activation (detected by pERK staining in the PBN). We next asked whether the anorexic response to icv FGF1 administration can be blunted by systemic administration of a GABAA receptor agonist. Consistent with this hypothesis, we found that continuous subcutaneous infusion of the GABAA receptor agonist Bretazenil blunts the anorexic response to icv FGF1 injection by ~50% at a dose that has no effect intake in control mice. Similarly, the effect of FGF1 to induce c-Fos in the PBN was largely blocked by Bretazenil, and our preliminary findings indicate that CGRP neurons are among those in which this effect occurred. Together, these data suggest that FGF1-induced anorexia results from reduced GABAergic inhibition of PBNCGRP neurons. Disclosure J.M.Scarlett: None. K.M.Alonge: None. B.N.Phan: None. G.J.Morton: Research Support; Novo Nordisk A/S. M.W.Schwartz: Consultant; NodThera, Research Support; Novo Nordisk A/S. Funding U.S. Department of Defense (PRMRP W81XWH-21-1-0635); National Institutes of Health (DK083042)

Sustained remission of type 2 diabetes in rodents by centrally administered fibroblast growth factor 4

Type 2 diabetes (T2D) is a major health and economic burden worldwide. Despite the availability of multiple drugs for short-term management, sustained remission of T2D is currently not achievable pharmacologically. Intracerebroventricular administration of fibroblast growth factor 1 (icvFGF1) induces sustained remission in T2D rodents, propelling intense research efforts to understand its mechanism of action. Whether other FGFs possess similar therapeutic benefits is currently unknown. Here, we show that icvFGF4 also elicits a sustained antidiabetic effect in both male db/db mice and diet-induced obese mice by activating FGF receptor 1 (FGFR1) expressed in glucose-sensing neurons within the mediobasal hypothalamus. Specifically, FGF4 excites glucose-excited (GE) neurons while inhibiting glucose-inhibited (GI) neurons. Moreover, icvFGF4 restores the percentage of GI neurons in db/db mice. Importantly, intranasal delivery of FGF4 alleviates hyperglycemia in db/db mice, paving the way for non-invasive therapy. We conclude that icvFGF4 holds significant therapeutic potential for achieving sustained remission of T2D.

The Roles of Fibroblast Growth Factor Receptor 3 (FGFR3) in the Spectrum of Skeletal Dysplasia

The fibroblast growth factor receptor 3 (FGFR3) gene mutations were identified to be involved in the pathogenesis of most chondropathies. The FGFR3 gene encodes the FGFR3 receptor and is involved in the regulation of bone growth by limiting the ossification of long bones. Mutations of the FGFR3 gene result in abnormal cell proliferation and improper cartilage development. We aim to provide an overview of the roles of FGFR3 in skeletal dysplasia by highlighting the pathogenesis, clinical variants of skeletal dysplasia, diagnosis, and their management.
 Achondroplasia is the most common form of chondropathies, occurring in approximately 1 in 20,000-30,000 live births, and it is the most common form of genetic dwarfism. In over 80% of cases of achondroplasia, the mutation is sporadic, and only 20% are inherited autosomal dominant. Achondroplasia results from a point mutation in the gene encoding the transmembrane portion of FGFR3. Two viable base substitutions are identified in achondroplasia, including a point mutation of guanine substituted for adenine (c.1138G>A); this is identified in approximately 98% of the affected individuals, and transversion of guanine to cytosine (c.1138G>C).
 Hypochondroplasia is a milder form of chondropathies with an incidence between 1 in 33,000 and 1 in 47,000 live births. Missense mutations of FGFR3 (p.Asn540Lys) are isolated in tyrosine kinase domain I occurring in approximately 60% of cases, and missense mutation of FGFR3 (p.Lys650Asn) identified in the tyrosine kinase domain II of FGFR3. Thanatophoric dysplasia is the most lethal form of chondropathies, with neonatal fetal death secondary to pulmonary hypoplasia. In thanatophoric dysplasia, there is Lys650Met substitution in FGFR3 (Type I) with impairment of endochondral bone growth and a pathogenic variant of p.Lys650Glu substitution in FGFR3 (Type II). In addition, specific amino acid substitution in the FGFR3 gene (G380R) was identified to be associated with severe achondroplasia with developmental delay and acanthosis nigricans (SADDAN).
 The diagnosis of achondroplasias is routinely made from clinical presentations and radiological findings. FGFR3 molecular genetic testing is performed in children with atypical presentations. In addition, a pre-implantation genetic diagnosis should be available for parents pursuing in-vitro fertilization and embryo implantation procedures. Management of chondropathies includes symptomatic treatment with drugs, surgical intervention, and lifelong follow-up care. Different pharmacological options have been used, including those that directly block FGFR3 activation or regulate signalling pathways controlling chondrocyte proliferation and differentiation.

Activated FGFR3 suppresses bone regeneration and bone mineralization in an ovariectomized mouse model

BackgroundPostmenopausal osteoporosis is a widespread health concern due to its prevalence among older adults and an associated high risk of fracture. The downregulation of bone regeneration delays fracture healing. Activated fibroblast growth factor receptor 3 (FGFR3) accelerates bone regeneration at juvenile age and downregulates bone mineralization at all ages. However, the impact of FGFR3 signaling on bone regeneration and bone mineralization post-menopause is still unknown. This study aimed to evaluate the impact of FGFR3 signaling on bone regeneration and bone mineralization during menopause by developing a distraction osteogenesis (DO) mouse model after ovariectomy (OVX) using transgenic mice with activated FGFR3 driven by Col2a1 promoter (Fgfr3 mice).MethodsThe OVX or sham operations were performed in 8-week-old female Fgfr3 and wild-type mice. After 8 weeks of OVX surgery, DO surgery in the lower limb was performed. The 5-day-latency period followed by performing distraction for 9 days. Bone mineral density (BMD) and bone regeneration was assessed by micro-computed tomography (micro-CT) scan and soft X-ray. Bone volume in the distraction area was also evaluated by histological analysis after 7 days at the end of distraction. Osteogenic differentiation and mineralization of bone marrow-derived mesenchymal stem cells (BMSCs) derived from each mouse after 8 weeks of the OVX or sham operations were also evaluated with and without an inhibitor for FGFR3 signaling (meclozine).ResultsBMD decreased after OVX in both groups, and it further deteriorated in Fgfr3 mice. Poor callus formation after DO was also observed in both groups with OVX, and the amount of regenerated bone was further decreased in Fgfr3 mice. Similarly, histological analysis revealed that Fgfr3 OVX mice showed lower bone volume. Osteogenic differentiation and mineralization of BMSCs were also deteriorated in Fgfr3 OVX mice. An inhibitor for FGFR3 signaling dramatically reversed the inhibitory effect of OVX and FGFR3 signaling on BMSC mineralization.ConclusionUpregulated FGFR3 decreased newly regenerated bone after DO and BMD in OVX mice. FGFR3 signaling can be a potential therapeutic target in patients with postmenopausal osteoporosis.

Direct and indirect effects of fibroblast growth factor 23 on the heart.

Fibroblast growth factor (FGF)23 is a bone-derived phosphotropic hormone that regulates phosphate and mineral homeostasis. Recent studies have provided evidence that a high plasma concentration of FGF23 is associated with cardiac disease, including left ventricular hypertrophy (LVH), heart failure, atrial fibrillation, and cardiac death. Experimental studies have shown that FGF23 activates fibroblast growth factor receptor 4 (FGFR4)/phospholipase Cγ/calcineurin/nuclear factor of activated T-cells signaling in cardiomyocytes and induces cardiac hypertrophy in rodents. Activation of FGFR4 by FGF23 normally requires the co-receptor α-klotho, and klotho-independent signaling occurs only under conditions characterized by extremely high FGF23 concentrations. Recent studies have demonstrated that FGF23 activates the renin-angiotensin-aldosterone system (RAAS) and induces LVH, at least in part as a result of lower vitamin D activation. Moreover, crosstalk between FGF23 and RAAS results in the induction of cardiac hypertrophy and fibrosis. In this review, we summarize the results of studies regarding the relationships between FGF23 and cardiac events, and describe the potential direct and indirect mechanisms whereby FGF23 induces LVH.

Molecular and Immunohistochemical assessment of Fibroblast Growth Factor Receptor 3 (FGFR3) gene as a survival time predictor in bladder cancer patients

BACKGROUND: Mutation signatures contributing to the tumorigenesis of bladder cancer (BC) are complex and heterogeneous, resulting in unpredictable progression, recurrence, and time survival. Clinically, useful prognostic and predictive biomarkers for both disease recurrence and surveillance are therefore needed. Activating fibroblast growth factor receptor 3 (FGFR3) mutations are regarded as early drivers in the molecular pathogenesis of BC. AIM: The aim of the present study is to evaluate the frequency and distribution pattern of FGFR3 mutation in urine sediments of BC patients in relation to its immunohistochemical (IHC) and molecular expression and to determine the prognostic and predictive value of FGFR3 relative to BC. PATIENTS AND METHODS: One hundred and sixty patients with diagnosed BC and 80 healthy controls were recruited. Urine samples were  collected from all participants. DNA was extracted and FGFR3 mutations were examined in exons 7, 10, and 15 by polymerase chain reaction. IHC for FGFR3 expression and fluorescence in situ hybridization technique for assessment of gene amplification was also applied in tissue sections. RESULTS: Ninety-eight (61.3%) patients were mutant in exon 7, 82 (51.3%) were mutant in exon 10, while only 14 (8.8%) were mutant in exon 15. Univariate logistic regression analysis revealed that mutations in the three exons of FGFR3 were statistically associated with BC and could be used as predictor and/or prognostic parameters for BC. Receiver operating characteristic analysis showed that the mutation of exons 7 and 10 could be used as diagnostic biomarkers for BC. Our findings confirm that FGFR3 mutations are associated with tumors of low grade and stage. The prevalence of mutations was significantly associated with recurrence and survival time of patients for all exons. Kaplan–Meier analysis revealed a significant association between mutant patients in exon 10 and survival time. Our findings suggest that estimation of FGFR3 expression and gene amplification could serve as a prognostic indicator in the follow-up of BC patients. It could also be utilized for molecular targeted therapy in BC. CONCLUSION: Our data confirmed the feasibility of FGFR3 mutation detection in urine sediment. FGFR3 genetic mutations are independent prognostic factors for tumor recurrence and the genetic alternation of FGFR3 could be used for prediction of survival time of BC patients.

Paricalcitol Improved Cardiac Hypertrophy and Fibrosis through Upregulation of Fibroblast Growth Factor-23 and Downregulation of Transforming Growth Factor-beta in a Rat Model of Isoproterenol-Induced Cardiomyopathy

Acute cardiomyopathy is a significant global health concern and one of the leading causes of death in developed countries. Prior studies have shown an association between acute cardiomyopathy and low vitamin D levels. Although paricalcitol, a vitamin D receptor (VDR) activator, has demonstrated clinical benefits in patients with advanced kidney disease, its effect on cardiac remodeling in cardiomyopathy is unknown. This study aimed to investigate the relative effects of paricalcitol on cardiomyopathy in rats. Wistar–Kyoto rats were administered vehicle (sham control group) or isoproterenol to induce cardiomyopathy. Rats administered isoproterenol were subsequently treated with paricalcitol (experimental group) or vehicle (isoproterenol group). Picrosirius red and immunofluorescence staining were used to analyze cardiac fibrosis and hypertrophy. Immunohistochemistry staining was used to confirm the molecular mechanisms involved in isoproterenol-induced cardiomyopathy in rats. Injection of paricalcitol could reduce collagen and transforming growth factor-beta 1 (TGF-β1) levels while activating fibroblast growth factor receptor 1 (FGFR1) and fibroblast growth factor-23 (FGF23) without the help of Klotho, thereby reducing myocardial hypertrophy and fibrosis. As a VDR activator, paricalcitol reduces isoproterenol-induced cardiac fibrosis and hypertrophy by reducing the expression of TGF-β1 and enhancing the expression of VDR, FGFR1, and FGF23.

Meclozine ameliorates bone mineralization and growth plate structure in a mouse model of X‑linked hypophosphatemia.

X-linked hypophosphatemic rickets (XLH) is characterized by hypo-mineralization of the bone due to hypophosphatemia. XLH is caused by abnormally high levels of fibroblast growth factor 23, which trigger renal phosphate wasting. Activated fibroblast growth factor receptor 3 (FGFR3) signaling is considered to be involved in XLH pathology. Our previous study revealed that meclozine attenuated FGFR3 signaling and promoted longitudinal bone growth in an achondroplasia mouse model. The present study aimed to examine whether meclozine affected the bone phenotype in a mouse model of XLH [X-linked hypophosphatemic (Hyp) mice]. Meclozine was administered orally to 7-day-old Hyp mice for 10 days, after which the mice were subjected to blood sampling and histological analyses of the first coccygeal vertebra, femur and tibia. Villanueva Goldner staining was used to assess bone mineralization, hematoxylin and eosin staining was used to determine the growth plate structure and tartrate-resistant acid phosphatase staining was used to measure osteoclast activity. The osteoid volume/bone volume of cortical bone was lower in meclozine-treated Hyp mice compared with untreated Hyp mice. Meclozine treatment improved the abnormally thick hypertrophic zone of the growth plate and ameliorated the downregulation of osteoclast surface/bone surface in Hyp mice. However, meclozine had only a marginal effect on mineralization in the trabecular bone and on calcium and phosphate plasma levels. A 10-day-tratment with meclozine partially ameliorated bone mineralization in Hyp mice; hence, meclozine could alleviate XLH symptoms.

Abstract 13932: Association of Heparin Exposure With 5-year Mortality and Heart Failure in Patients With End-Stage Kidney Disease on Hemodialysis

Introduction: Fibroblast growth factor (FGF) 23 is strongly upregulated in end-stage renal disease (ESRD) on dialysis and induces left ventricular hypertrophy (LVH) through activation of cardiac FGF receptor 4. Recent experimental animal data suggest that heparin acts as a co-receptor for FGF23, promoting binding to cardiac cells and LVH. Hypothesis We hypothesized that mortality and HF risk would be higher among patients with ESRD on hemodialysis who are regularly exposed to heparin during dialysis sessions. Methods: Using data from the TriNetX Research Network, we identified patients with ESRD (ICD-10 code N18.6) who received dialysis services (Z49.X) or were dependent on dialysis (Z99.2), for ≥5 instances 1 month apart, during years 2011-2017. Patients were stratified by heparin exposure during dialysis (≥5 instances vs. no exposure). Patients on peritoneal dialysis were excluded. We examined 5-year mortality and HF risk, after matching for demographics, background conditions, laboratory values, and vital signs at baseline. We used Kaplan-Meier estimates for incidence and Cox proportional hazards models for hazard ratios. Results: We matched 2131 patients who were exposed to heparin (≥5 instances) during dialysis and 2131 who were not. The two cohorts were balanced for characteristics, as evident from standardize mean differences <0.1, Table 1. Kaplan-Meier mortality at 5 years was 44.4% in the heparin-exposed cohort vs. 31.4% in the non-exposed cohort (HR 1.39, 95%CI 1.24-1.55; P<0.001). Incidence of HF at 5 years was also higher with heparin exposure: 44.3% vs. 34.0% in the non-exposed cohort (HR 1.35, 95% CI 1.17-1.5; P<0.001). Conclusion In this comparative retrospective study of propensity score matched patients with ESRD on dialysis, regular exposure to heparin was associated with higher mortality and HF risk at 5 years. Despite the shortcomings of a retrospective study, these hypothesis-generating findings merit investigation in prospective studies.

AZD4547 and the Alleviation of Hepatoma Cell Sorafenib Resistance via the Promotion of Autophagy.

This study is part of a larger research effort to explore the molecular mechanism of hepatocellular carcinoma, reduce drug resistance and seek new targets. The objective of this study is to investigate the effect and mechanism of fibroblast growth factor receptor inhibitor AZD4547 on Sorafenib-resistant hepatoma cells. First, we constructed a Sorafenib-resistant hepatoma cell line Huh7R. Different groups of Huh7R cells were treated with Sorafenib, AZD4547, Sorafenib combined with AZD4547, and normal saline. The cell viability was detected by Cell Counting Kit-8. Then Fibroblast growth factor receptor and Toll-like receptor 4 were detected by Western blot, as well as the LC3 II/I, Beclin1, and P62. In addition, we used the autophagy inhibitor 3-methyladenine to identify the mechanism of AZD4547 combined with Sorafenib for inducing Sorafenib-resistant hepatoma cell death. We find that AZD4547 combined with Sorafenib significantly inhibited the viability of Sorafenib-resistant hepatoma cell Huh7R. As for its mechanism, AZD4547 was able to inhibit fibroblast growth factor receptor activity, promote autophagy and regulate immunity. AZD4547 increased LC3 II/I, Beclin1, and Toll-like receptor 4 proteins, and decreased P62 protein level in Huh7R cells significantly when given in combination with sorafenib. Furthermore, 3-methyladenine inhibited autophagy and reversed the killing effect of the combination of AZD4547 and Sorafenib on Huh7R cells. The inhibition of fibroblast growth factor receptor activity by AZD4547 can significantly enhance autophagy and immune response, as well as promote the death of Sorafenib-resistant hepatoma cells.

FGFR3 Mutational Activation Can Induce Luminal-like Papillary Bladder Tumor Formation and Favors a Male Sex Bias

BackgroundBladder cancer (BCa) is more common in men and presents differences in molecular subtypes based on sex. Fibroblast growth factor receptor 3 (FGFR3) mutations are enriched in the luminal papillary muscle-invasive BCa (MIBC) and non-MIBC subtypes. ObjectiveTo determine whether FGFR3 mutations initiate BCa and impact BCa male sex bias. Design, setting, and participantsWe developed a transgenic mouse model expressing the most frequent FGFR3 mutation, FGFR3-S249C, in urothelial cells. Bladder tumorigenesis was monitored in transgenic mice, with and without carcinogen exposure. Mouse and human BCa transcriptomic data were compared. InterventionMutant FGFR3 overexpression in mouse urothelium and siRNA knockdown in cell lines, and N-butyl-N(4-hydroxybutyl)-nitrosamine (BBN) exposure. Outcome measurements and statistical analysisImpact of transgene dosage on tumor frequency, synergy with BBN treatment, and FGFR3 pathway activation were analyzed. The sex-specific incidence of FGFR3-mutated tumors was evaluated in mice and humans. FGFR3 expression in FGFR3-S249C mouse urothelium and in various human epithelia was measured. Mutant FGFR3 regulation of androgen (AR) and estrogen (ESR1) receptor activity was evaluated, through target gene expression (regulon) and reporter assays. Results and limitationsFGFR3-S249C expression in mice induced low-grade papillary BCa resembling human luminal counterpart at histological, genomic, and transcriptomic levels, and promoted BBN-induced basal BCa formation. Mutant FGFR3 expression levels impacted tumor incidence in mice, and mutant FGFR3–driven human tumors were restricted to epithelia presenting high normal FGFR3 expression levels. BCa male sex bias, also found in our model, was even higher in human FGFR3-mutated tumors compared with wild-type tumors and was associated with higher AR and lower ESR1 regulon activity. Mutant FGFR3 expression inhibited both ESR1 and AR activity in mouse tumors and human cell lines, demonstrating causation only between FGFR3 activation and low ESR1 activity in tumors. ConclusionsMutant FGFR3 initiates luminal papillary BCa formation and favors BCa male sex bias, potentially through FGFR3-dependent ESR1 downregulation. Patients with premalignant lesions or early-stage BCa could thus potentially benefit from FGFR3 targeting. FGFR3 expression level in epithelia could account for FGFR3-driven carcinoma tissue specificity. Patient summaryBy developing a transgenic mouse model, we showed that gain-of-function mutations of FGFR3 receptor, among the most frequent genetic alterations in bladder cancer (BCa), initiate BCa formation. Our results could support noninvasive detection of FGFR3 mutations and FGFR3 targeting in early-stage bladder lesions.

Ang II (Angiotensin II)–Induced FGFR1 (Fibroblast Growth Factor Receptor 1) Activation in Tubular Epithelial Cells Promotes Hypertensive Kidney Fibrosis and Injury

Elevated Ang II (angiotensin II) level leads to a range of conditions, including hypertensive kidney disease. Recent evidences indicate that FGFR1 (fibroblast growth factor receptor 1) signaling may be involved in kidney injuries. In this study, we determined whether Ang II alters FGFR1 signaling to mediate renal dysfunction. Human archival kidney samples from patients with or without hypertension were examined. Multiple genetic and pharmacological approaches were used to investigate FGFR1-mediated signaling in tubular epithelial NRK-52E cells in response to Ang II stimulation. C57BL/6 mice were infused with Ang II for 28 days to develop hypertensive kidney disease. Mice were treated with either adeno-associated virus expressing FGFR1 shRNA or FGFR1 inhibitor AZD4547. Kidney specimens from subjects with hypertension and mice challenged with Ang II have increased FGFR1 activity in renal epithelial cells. Renal epithelial cells in culture initiate extracellular matrix programming in response to Ang II, through the activation of FGFR1, which is independent of both AT1R (angiotensin II receptor type 1) and AT2R (angiotensin II receptor type 2). The RNA sequencing analysis indicated that disrupting FGFR1 suppresses Ang II-induced fibrogenic responses in epithelial cells. Mechanistically, Ang II-activated FGFR1 leads to STAT3 (signal transducer and activator of transcription 3) activation, which is responsible for fibrogenic factor expression in kidneys. In the mouse model of hypertensive kidney disease, genetic knockdown of FGFR1 or pharmacological inhibition of its activity protected kidneys from dysfunction and fibrosis upon Ang II challenge. Our studies uncover a novel mechanism causing renal fibrosis in hypertension and indicate FGFR1 as a potential target to preserve renal function and integrity.