FGFs, their receptors, and human limb malformations: clinical and molecular correlations

Midface hypoplasia in syndromic craniosynostosis: predicting craniofacial growth via a novel regression model from anatomical morphometric analysis

Midface hypoplasia in syndromic craniosynostosis (SC) may lead to serious respiratory issues. The aim of this study was to analyse the morphometric correlation between midface and cranial base parameters in paediatric SC patients in order to formulate predictive regression models. The computed tomography scans of 18 SC patients and 20 control were imported into Materialise Mimics Medical version 21.0 software for the measurement of multiple craniofacial landmarks and correlation analysis. The results showed a strong correlation of anterior cranial base (SN), posterior cranial base (SBa), and total cranial base (NBa) (r = 0.935) to maxilla length and width (ZMR-ZML) (r = 0.864). The model of NBa = - 1.554 + 1.021(SN) + 0.753(SBa) with R2 = 0.875 is proposed to demonstrate the development of the cranial base that causes a certain degree of midface hypoplasia in SC patients. The formula is supported using a prediction model of ZMR-ZML = 5.762 + 0.920(NBa), with R2 = 0.746. The mean absolute difference and standard deviation between the predicted and true NBa and ZMR-ZML were 2.08 ± 1.50 mm and 3.11 ± 2.32 mm, respectively. The skeletal growth estimation models provide valuable foundation for further analysis and potential clinical application.

Revealing the pharmacological effects of Remodelin against osteosarcoma based on network pharmacology, acRIP-seq and experimental validation

Osteosarcoma (OS) is the most common primary malignant tumor of bone. Remodelin, an inhibitor of the N (4)-Acetylcytidine (ac4C) acetylation modifying enzyme N-acetyltransferase 10 (NAT10), has been shown to have therapeutic effects on cancer in several studies, and our previous studies have confirmed the inhibitory effect of Remodelin on OS cells, however, the mechanism of action has not yet been elucidated. We used network pharmacological analysis to quantify the therapeutic targets of Remodelin against OS. acRIP-seq and RNA-seq were performed to investigate the inhibitory activity of Remodelin on acetylation and its effect on the transcriptome after intervening in OS cells U2OS with Remodelin in vitro. Key target genes were deduced based on their pharmacological properties, combined with network pharmacology results and sequencing results. Finally, the deduced target genes were validated with vitro experiments. Network pharmacological analysis showed that 2291 OS-related target genes and 369 Remodelin-related target genes were obtained, and 116 overlapping genes were identified as Remodelin targets for OS treatment. Sequencing results showed that a total of 13,736 statistically significant ac4C modification peaks were detected by acRIP-seq, including 6938 hypoacetylation modifications and 6798 hyperacetylation modifications. A total of 2350 statistically significant mRNAs were detected by RNA-seq, of which 830 were up-regulated and 1520 were down-regulated. Association analyses identified a total of 382 genes that were Hypoacetylated-down, consistent with inhibition of mRNA acetylation and expression by Remodelin. Five genes, CASP3, ESR2, FGFR2, IGF1 and MAPK1, were identified as key therapeutic targets of Remodelin against OS. Finally, in vitro experiments, CCK-8 and qRT-PCR demonstrated that Remodelin indeed inhibited the proliferation of OS cells and reduced the expression of three genes: ESR2, IGF1, and MAPK1. In conclusion, ESR2, IGF1 and MAPK1 were identified as key therapeutic targets of Remodelin against OS. This reveals the target of Remodelin's pharmacological action on OS and provides new ideas for the treatment of OS.

Integrated DNA Copy Number and Expression Profiling Identifies IGF1R as a Prognostic Biomarker in Pediatric Osteosarcoma

Osteosarcoma is a primary malignant bone tumor arising from bone-forming mesenchymal cells in children and adolescents. Despite efforts to understand the biology of the disease and identify novel therapeutics, the survival of osteosarcoma patients remains dismal. We have concurrently profiled the copy number and gene expression of 226 osteosarcoma samples as part of the Strategic Partnering to Evaluate Cancer Signatures (SPECS) initiative. Our results demonstrate the heterogeneous landscape of osteosarcoma in younger populations by showing the presence of genome-wide copy number abnormalities occurring both recurrently among samples and in a high frequency. Insulin growth factor receptor 1 (IGF1R) is a receptor tyrosine kinase which binds IGF1 and IGF2 to activate downstream pathways involved in cell apoptosis and proliferation. We identify prevalent amplification of IGF1R corresponding with increased gene expression in patients with poor survival outcomes. Our results substantiate previously tenuously associated copy number abnormalities identified in smaller datasets (13q34+, 20p13+, 4q35-, 20q13.33-), and indicate the significance of high fibroblast growth factor receptor 2 (FGFR2) expression in distinguishing patients with poor prognosis. FGFR2 is involved in cellular proliferation processes such as division, growth and angiogenesis. In summary, our findings demonstrate the prognostic significance of several genes associated with osteosarcoma pathogenesis.

Exokine and the Youth-Boosting Treatment Based on One's Own Serum: Wheat and Chaff

Within the field of skin rejuvenation, clinicians have broadened the application of proven therapies toward antiaging medicine. Specifically, both platelet-rich plasma (PRP) and autologous-conditioned serum (ACS) have received great consideration among experts for novel indications. While the medical research focused on ACS is strengthened in their evidence and supported by promising outcomes, much more debates exist regarding the efficacy of PRP. Despite limited supporting literature to date, physicians and surgeons should be encouraged to explore the use of these approaches and in shedding further light on their potential benefits by contributing new evidence from basic and clinical scientific investigation.

FGFR2 accommodates osteogenic cell fate determination in human mesenchymal stem cells

The multilineage differentiation potential of human mesenchymal stem cells (hMSCs) underpins their clinical utility for tissue regeneration. Control of such cell-fate decisions is tightly regulated by different growth factors/cytokines and their cognate receptors. Fibroblast growth factors (FGFs) are among such factors critical for osteogenesis. However, how FGF receptors (FGFRs) help to orchestrate osteogenic progression remains to be fully elucidated. Here, we studied the protein levels of FGFRs during osteogenesis in human adult bone marrow-derived MSCs and discovered a positive correlation between FGFR2 expression and alkaline phosphatase (ALP) activity, an early marker of osteogenesis. Through RNA interference studies, we confirmed the role of FGFR2 in promoting the osteogenic differentiation of hMSCs. Knockdown of FGFR2 resulted in downregulation of pro-osteogenic genes and upregulation of pro-adipogenic genes and adipogenic commitment. Moreover, under osteogenic induction, FGFR2 knockdown resulted in upregulation of Enhancer of Zeste Homolog 2 (EZH2), an epigenetic enzyme that regulates MSC lineage commitment and suppresses osteogenesis. Lastly, we show that serial-passaged hMSCs have reduced FGFR2 expression and impaired osteogenic potential. Our study suggests that FGFR2 is critical for mediating osteogenic fate by regulating the balance of osteo-adipogenic lineage commitment. Therefore, examining FGFR2 levels during serial-passaging of hMSCs may prove useful for monitoring their multipotency.

FGFR signaling and endocrine resistance in breast cancer: Challenges for the clinical development of FGFR inhibitors

Fibroblast growth factors (FGFs) and their receptors (FGFRs) have been extensively investigated in solid malignancies, representing an attractive therapeutic target. In breast cancer, especially in estrogen receptor positive (ER+) subtype, FGFR signaling aberrations have been reported to contribute to proliferation, dedifferentiation, metastasis and drug resistance. However, clinical trials evaluating the use of FGFR inhibitors in breast cancer have had disappointing results. The different biological properties of distinct FGFR alterations and lack of established patient selection criteria, in addition to the early use of non-selective inhibitors, are possible reasons of this failure. Herein, we review the current knowledge regarding the role of FGFR signaling in endocrine resistance in breast cancer. We will also summarize the results from the clinical development of FGFR inhibitors in breast cancer, discussing future challenges to identify the correct cohorts of patients to enroll in trials testing FGFR inhibitors.

TCF12 haploinsufficiency causes autosomal dominant Kallmann syndrome and reveals network-level interactions between causal loci

Dysfunction of the gonadotropin-releasing hormone (GnRH) axis causes a range of reproductive phenotypes resulting from defects in the specification, migration and/or function of GnRH neurons. To identify additional molecular components of this system, we initiated a systematic genetic interrogation of families with isolated GnRH deficiency (IGD). Here, we report 13 families (12 autosomal dominant and one autosomal recessive) with an anosmic form of IGD (Kallmann syndrome) with loss-of-function mutations in TCF12, a locus also known to cause syndromic and non-syndromic craniosynostosis. We show that loss of tcf12 in zebrafish larvae perturbs GnRH neuronal patterning with concomitant attenuation of the orthologous expression of tcf3a/b, encoding a binding partner of TCF12, and stub1, a gene that is both mutated in other syndromic forms of IGD and maps to a TCF12 affinity network. Finally, we report that restored STUB1 mRNA rescues loss of tcf12 in vivo. Our data extend the mutational landscape of IGD, highlight the genetic links between craniofacial patterning and GnRH dysfunction and begin to assemble the functional network that regulates the development of the GnRH axis.

Cell death in the developing vertebrate limb: A locally regulated mechanism contributing to musculoskeletal tissue morphogenesis and differentiation

Our aim is to critically review current knowledge of the function and regulation of cell death in the developing limb. We provide a detailed, but short, overview of the areas of cell death observed in the developing limb, establishing their function in morphogenesis and structural development of limb tissues. We will examine the functions of this process in the formation and growth of the limb primordia, formation of cartilaginous skeleton, formation of synovial joints, and establishment of muscle bellies, tendons, and entheses. We will analyze the plasticity of the cell death program by focusing on the developmental potential of progenitors prior to death. Considering the prolonged plasticity of progenitors to escape from the death process, we will discuss a new biological perspective that explains cell death: this process, rather than secondary to a specific genetic program, is a consequence of the tissue building strategy employed by the embryo based on the formation of scaffolds that disintegrate once their associated neighboring structures differentiate.

We examine the functions of cell death in the formation and growth of the limb primordia.

We analyze the plasticity of the cell death program by focusing on the developmental potential of progenitors prior to death.

Considering the prolonged plasticity of progenitors to escape from the death process and the absence of defined genetic program in their regulation we propose that cell death is a consequence of the tissue building strategy employed by the embryo regulated by epigenetic factors .

Bone Marrow Multipotent Mesenchymal Stromal Cells in Patients with Diffuse Large B-Cell Lymphoma

In diffuse large B-cell lymphoma, bone marrow involvement is rarely diagnosed. We compared the properties of bone marrow stromal progenitor cells and the concentration of fibroblast CFU in patients with diffuse large B-cell lymphoma without bone marrow involvement and in healthy donors. It was found that the properties of multipotent mesenchymal stromal cells in patients in the debut of the disease differed considerably from those in healthy donors. In particular, the total cell production in patients was significantly higher than in donors. In multipotent mesenchymal stromal cells of patients, some cell parameters were changes; the mean fluorescence intensity of the adhesion molecule ICAM1 on the cell surface was increased. The mean fluorescence intensity of mesenchymal stromal cell markers (HLA-ABC, CD73 and CD90) was significantly elevated. The relative expression of BMP4, MMP2, FGFR1, and ICAM1 genes in mesenchymal stromal cell was reduced, while the expression of FGFR2 gene was enhanced. Despite the absence of proven involvement of the bone marrow, the properties of mesenchymal stromal cells, the components in the stromal microenvironment niche regulating hemopoiesis are altered in patients with diffuse large B-cell lymphoma.

Receptor Tyrosine Kinase-Targeted Cancer Therapy

In the past two decades, several molecular targeted inhibitors have been developed and evaluated clinically to improve the survival of patients with cancer. Molecular targeted inhibitors inhibit the activities of pathogenic tyrosine kinases. Particularly, aberrant receptor tyrosine kinase (RTK) activation is a potential therapeutic target. An increased understanding of genetics, cellular biology and structural biology has led to the development of numerous important therapeutics. Pathogenic RTK mutations, deletions, translocations and amplification/over-expressions have been identified and are currently being examined for their roles in cancers. Therapies targeting RTKs are categorized as small-molecule inhibitors and monoclonal antibodies. Studies are underway to explore abnormalities in 20 types of RTK subfamilies in patients with cancer or other diseases. In this review, we describe representative RTKs important for developing cancer therapeutics and predicting or evaluated resistance mechanisms.

Runx2 is required for the proliferation of osteoblast progenitors and induces proliferation by regulating Fgfr2 and Fgfr3

Runx2 and Sp7 are essential transcription factors for osteoblast differentiation. However, the molecular mechanisms responsible for the proliferation of osteoblast progenitors remain unclear. The early onset of Runx2 expression caused limb defects through the Fgfr1–3 regulation by Runx2. To investigate the physiological role of Runx2 in the regulation of Fgfr1–3, we compared osteoblast progenitors in Sp7^−/− and Runx2^−/− mice. Osteoblast progenitors accumulated and actively proliferated in calvariae and mandibles of Sp7^−/− but not of Runx2^−/− mice, and the number of osteoblast progenitors and their proliferation were dependent on the gene dosage of Runx2 in Sp7^−/− background. The expression of Fgfr2 and Fgfr3, which were responsible for the proliferation of osteoblast progenitors, was severely reduced in Runx2^−/− but not in Sp7^−/− calvariae. Runx2 directly regulated Fgfr2 and Fgfr3, increased the proliferation of osteoblast progenitors, and augmented the FGF2-induced proliferation. The proliferation of Sp7^−/− osteoblast progenitors was enhanced and strongly augmented by FGF2, and Runx2 knockdown reduced the FGF2-induced proliferation. Fgfr inhibitor AZD4547 abrogated all of the enhanced proliferation. These results indicate that Runx2 is required for the proliferation of osteoblast progenitors and induces proliferation, at least partly, by regulating Fgfr2 and Fgfr3 expression.

Developmental and Evolutionary Significance of the Zygomatic Bone

The zygomatic bone is derived evolutionarily from the orbital series. In most modern mammals the zygomatic bone forms a large part of the face and usually serves as a bridge that connects the facial skeleton to the neurocranium. Our aim is to provide information on the contribution of the zygomatic bone to variation in midfacial protrusion using three samples; humans, domesticated dogs, and monkeys. In each case, variation in midface protrusion is a heritable trait produced by one of three classes of transmission: localized dysmorphology associated with single gene dysfunction, selective breeding, or long‐term evolution from a common ancestor. We hypothesize that the shape of the zygomatic bone reflects its role in stabilizing the connection between facial skeleton and neurocranium and consequently, changes in facial protrusion are more strongly reflected by the maxilla and premaxilla. Our geometric morphometric analyses support our hypothesis suggesting that the shape of the zygomatic bone has less to do with facial protrusion. By morphometrically dissecting the zygomatic bone we have determined a degree of modularity among parts of the midfacial skeleton suggesting that these components have the ability to vary independently and thus can evolve differentially. From these purely morphometric data, we propose that the neural crest cells that are fated to contribute to the zygomatic bone experience developmental cues that distinguish them from the maxilla and premaxilla. The spatiotemporal and molecular identity of the cues that impart zygoma progenitors with their identity remains an open question that will require alternative data sets. Anat Rec, 299:1616–1630, 2016. © 2016 The Authors The Anatomical Record Published by Wiley Periodicals, Inc.

Bone marker gene expression in calvarial bones: different bone microenvironments

Background

In calvarial mice, mesenchymal stem cells (MSCs) differentiate into osteoprogenitor cells and then differentiate into osteoblasts that differentiate into osteocytes, which become embedded within the bone matrix. In this case, the cells participating in bone formation include MSCs, osteoprogenitor cells, osteoblasts and osteocytes. The calvariae of C57BL/KaLwRijHsD mice consist of the following five bones: two frontal bones, two parietal bones and one interparietal bone. This study aimed to analyse some bone marker genes and bone related genes to determine whether these calvarial bones have different bone microenvironments.

Methods

C57BL/KaLwRijHsD calvariae were carefully excised from five male mice that were 4–6 weeks of age. Frontal, parietal, and interparietal bones were dissected to determine the bone microenvironment in calvariae. Haematoxylin and eosin staining was used to determine the morphology of different calvarial bones under microscopy. TaqMan was used to analyse the relative expression of Runx2, OC, OSX, RANK, RANKL, OPG, N-cadherin, E-cadherin, FGF2 and FGFR1 genes in different parts of the calvariae.

Results

Histological analysis demonstrated different bone marrow (BM) areas between the different parts of the calvariae. The data show that parietal bones have the smallest BM area compared to frontal and interparietal bones. TaqMan data show a significant increase in the expression level of Runx2, OC, OSX, RANKL, OPG, FGF2 and FGFR1 genes in the parietal bones compared with the frontal and interparietal bones of calvariae.

Conclusion

This study provides evidence that different calvarial bones, frontal, parietal and interparietal, contain different bone microenvironments.

Advances and challenges in targeting FGFR signalling in cancer

Fibroblast growth factors (FGFs) and their receptors (FGFRs) regulate numerous cellular processes. Deregulation of FGFR signalling is observed in a subset of many cancers, making activated FGFRs a highly promising potential therapeutic target supported by multiple preclinical studies. However, early-phase clinical trials have produced mixed results with FGFR-targeted cancer therapies, revealing substantial complexity to targeting aberrant FGFR signalling. In this Review, we discuss the increasing understanding of the differences between diverse mechanisms of oncogenic activation of FGFR, and the factors that determine response and resistance to FGFR targeting.

The two domain hypothesis of limb prepattern and its relevance to congenital limb anomalies

Functional annotation of mutations that cause human limb anomalies is enabled by basic developmental studies. In this study, we focus on the prepatterning stage of limb development and discuss a recent model that proposes anterior and posterior domains of the early limb bud generate two halves of the future skeleton. By comparing phenotypes in humans with those in model organisms, we evaluate whether this prepatterning concept helps to annotate human disease alleles. WIREs Dev Biol 2017, 6:e270. doi: 10.1002/wdev.270 For further resources related to this article, please visit the WIREs website.

Mutation c.943G>T (p.Ala315Ser) in FGFR2 Causing a Mild Phenotype of Crouzon Craniofacial Dysostosis in a Three-Generation Family

Crouzon syndrome craniofacial dysostosis type I [OMIM 123500] is caused by mutations in the gene encoding fibroblast growth factor receptor-2 (FGFR2). An overlapping phenotype with Muenke and Crouzon syndrome with acanthosis nigricans (FGFR3 mutations) is known. The clinical diagnosis can be corroborated by molecular studies in about 80-90% of the cases. No clear genotype/phenotype correlation has been identified yet. Here, we describe a second family with a mild phenotype in which the FGFR2 mutation c.943G>T leading to the amino acid substitution p.Ala315Ser was detected. Five affected family members showed craniofacial dysostosis without overt craniosynostosis. They all had midface hypoplasia. Crouzonoid appearance with mild protrusion of bulbi was only apparent in our index patient as well as obstructive sleep apnea episodes leading to reduced oxygen saturation; therefore, surgical intervention was suggested. One other affected family member additionally had iris coloboma.

BMPs are direct triggers of interdigital programmed cell death

During vertebrate embryogenesis the interdigital mesenchyme is removed by programmed cell death (PCD), except in species with webbed limbs. Although bone morphogenetic proteins (BMPs) have long been known to be players in this process, it is unclear if they play a direct role in the interdigital mesenchyme or if they only act indirectly, by affecting fibroblast growth factor (FGF) signaling. A series of genetic studies have shown that BMPs act indirectly by regulating the withdrawal of FGF activity from the apical ectodermal ridge (AER); this FGF activity acts as a cell survival factor for the underlying mesenchyme. Other studies using exogenous factors to inhibit BMP activity in explanted mouse limbs suggest that BMPs do not act directly in the mesenchyme. To address the question of whether BMPs act directly, we used an interdigit-specific Cre line to inactivate several genes that encode components of the BMP signaling pathway, without perturbing the normal downregulation of AER-FGF activity. Of three Bmps expressed in the interdigital mesenchyme, Bmp7 is necessary for PCD, but Bmp2 and Bmp4 both have redundant roles, with Bmp2 being the more prominent player. Removing BMP signals to the interdigit by deleting the receptor gene, Bmpr1a, causes a loss of PCD and syndactyly, thereby unequivocally proving that BMPs are direct triggers of PCD in this tissue. We present a model in which two events must occur for normal interdigital PCD: the presence of a BMP death trigger and the absence of an FGF survival activity. We demonstrate that neither event is required for formation of the interdigital vasculature, which is necessary for PCD. However, both events converge on the production of reactive oxygen species that activate PCD.

Positional plasticity in regenerating Amybstoma mexicanum limbs is associated with cell proliferation and pathways of cellular differentiation

Background

The endogenous ability to dedifferentiate, re-pattern, and re-differentiate adult cells to repair or replace damaged or missing structures is exclusive to only a few tetrapod species. The Mexican axolotl is one example of these species, having the capacity to regenerate multiple adult structures including their limbs by generating a group of progenitor cells, known as the blastema, which acquire pattern and differentiate into the missing tissues. The formation of a limb regenerate is dependent on cells in the connective tissues that retain memory of their original position in the limb, and use this information to generate the pattern of the missing structure. Observations from recent and historic studies suggest that blastema cells vary in their potential to pattern distal structures during the regeneration process; some cells are plastic and can be reprogrammed to obtain new positional information while others are stable. Our previous studies showed that positional information has temporal and spatial components of variation; early bud (EB) and apical late bud (LB) blastema cells are plastic while basal-LB cells are stable. To identify the potential cellular and molecular basis of this variation, we compared these three cell populations using histological and transcriptional approaches.

Results

Histologically, the basal-LB sample showed greater tissue organization than the EB and apical-LB samples. We also observed that cell proliferation was more abundant in EB and apical-LB tissue when compared to basal-LB and mature stump tissue. Lastly, we found that genes associated with cellular differentiation were expressed more highly in the basal-LB samples.

Conclusions

Our results characterize histological and transcriptional differences between EB and apical-LB tissue compared to basal-LB tissue. Combined with our results from a previous study, we hypothesize that the stability of positional information is associated with tissue organization, cell proliferation, and pathways of cellular differentiation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12861-015-0095-4) contains supplementary material, which is available to authorized users.

FGF signalling restricts haematopoietic stem cell specification via modulation of the BMP pathway

Haematopoietic stem cells (HSCs) are produced during embryogenesis from the floor of the dorsal aorta. The localization of HSCs is dependent on the presence of instructive signals on the ventral side of the vessel. The nature of the extrinsic molecular signals that control the aortic haematopoietic niche is currently poorly understood. Here we demonstrate a novel requirement for FGF signalling in the specification of aortic haemogenic endothelium. Our results demonstrate that FGF signalling normally acts to repress BMP activity in the subaortic mesenchyme through transcriptional inhibition of bmp4, as well as through activation of two BMP antagonists, noggin2 and gremlin1a. Taken together, these findings demonstrate a key role for FGF signalling in establishment of the developmental HSC niche via its regulation of BMP activity in the subaortic mesenchyme. These results should help inform strategies to recapitulate the development of HSCs in vitro from pluripotent precursors.

Molecular basis of cranial suture biology and disease: Osteoblastic and osteoclastic perspectives

The normal growth and development of the skull is a tightly regulated process that occurs along the osteogenic interfaces of the cranial sutures. Here, the borders of the calvarial bones and neighboring tissues above and below, function as a complex. Through coordinated remodeling efforts of bone deposition and resorption, the cranial sutures maintain a state of patency from infancy through early adulthood as the skull continues to grow and accommodate the developing brain's demands for expansion. However, when this delicate balance is disturbed, a number of pathologic conditions ensue; and if left uncorrected, may result in visual and neurocognitive impairments. A prime example includes craniosynostosis, or premature fusion of one or more cranial and/or facial suture(s). At the present time, the only therapeutic measure for craniosynostosis is surgical correction by cranial vault reconstruction. However, elegant studies performed over the past decade have identified several genes critical for the maintenance of suture patency and induction of suture fusion. Such deeper understandings of the pathogenesis and molecular mechanisms that regulate suture biology may provide necessary insights toward the development of non-surgical therapeutic alternatives for patients with cranial suture defects. In this review, we discuss the intricate cellular and molecular interplay that exists within the suture among its three major components: dura mater, osteoblastic related molecular pathways and osteoclastic related molecular pathways.

Quantification of facial skeletal shape variation in fibroblast growth factor receptor-related craniosynostosis syndromes

BACKGROUND

fibroblast growth factor receptor (FGFR) -related craniosynostosis syndromes are caused by many different mutations within FGFR-1, 2, 3, and certain FGFR mutations are associated with more than one clinical syndrome. These syndromes share coronal craniosynostosis and characteristic facial skeletal features, although Apert syndrome (AS) is characterized by a more dysmorphic facial skeleton relative to Crouzon (CS), Muenke (MS), or Pfeiffer syndromes.

METHODS

Here we perform a detailed three-dimensional evaluation of facial skeletal shape in a retrospective sample of cases clinically and/or genetically diagnosed as AS, CS, MS, and Pfeiffer syndrome to quantify variation in facial dysmorphology, precisely identify specific facial features pertaining to these four syndromes, and further elucidate what knowledge of the causative FGFR mutation brings to our understanding of these syndromes.

RESULTS

Our results confirm a strong correspondence between genotype and facial phenotype for AS and MS with severity of facial dysmorphology diminishing from Apert FGFR2(S252W) to Apert FGFR2(P253R) to MS. We show that AS facial shape variation is increased relative to CS, although CS has been shown to be caused by numerous distinct mutations within FGFRs and reduced dosage in ERF.

CONCLUSION

Our quantitative analysis of facial phenotypes demonstrate subtle variation within and among craniosynostosis syndromes that might, with further research, provide information about the impact of the mutation on facial skeletal and nonskeletal development. We suggest that precise studies of the phenotypic consequences of genetic mutations at many levels of analysis should accompany next-generation genetic research and that these approaches should proceed cooperatively.

Targeting molecular pathways in endometrial cancer: a focus on the FGFR pathway

In the majority of cases, endometrial cancer is localized and highly curable through surgery and adjuvant radiotherapy. However, for patients with advanced or metastatic disease, prognosis is poor. Systemic treatments such as cytotoxic chemotherapy or hormonal therapy can cause significant toxicities including chemotherapy-related gastrointestinal, neurologic, and immunosuppressive toxicities and hormone-related hypertension, increased blood sugar, thrombosis, and pulmonary emboli. In addition, these therapies rarely lead to sustained disease control. Novel therapies with greater efficacy and reduced toxicity are needed. Recent progress in the identification of genetic abnormalities in cell signaling proteins has spurred the development of targeted agents for the treatment of patients with endometrial cancer. The fibroblast growth factor receptor (FGFR) pathway is one of several signaling pathways that have been implicated in the pathogenesis and progression of endometrial cancer. The activity of novel FGFR-targeted agents in preclinical endometrial cancer models and clinical trials will be reviewed.

FGFR signalling in women's cancers

FGFs, in a complex with their receptors (FGFRs) and heparan sulfate (HS), are responsible for a range of cellular functions, from embryogenesis to metabolism. Both germ line and somatic FGFR mutations are known to play a role in a range of diseases, most notably craniosynestosis dysplasias, dwarfism and cancer. Because of the ability of FGFR signalling to induce cell proliferation, migration and survival, FGFRs are readily co-opted by cancer cells. Mutations in, and amplifications of, these receptors are found in a range of cancers with some of the most striking clinical findings relating to their contribution to pathogenesis and progression of female cancers. Here, we outline the molecular mechanisms of FGFR signalling and discuss the role of this pathway in women's cancers, focusing on breast, endometrial, ovarian and cervical carcinomas, and their associated preclinical and clinical data. We also address the rationale for therapeutic intervention and the need for FGFR-targeted therapy to selectively target cancer cells in view of the fundamental roles of FGF signalling in normal physiology.

Blockade of nonhormonal fibroblast growth factors by FP-1039 inhibits growth of multiple types of cancer

The fibroblast growth factor (FGF) pathway promotes tumor growth and angiogenesis in many solid tumors. Although there has long been interest in FGF pathway inhibitors, development has been complicated: An effective FGF inhibitor must block the activity of multiple mitogenic FGF ligands but must spare the metabolic hormone FGFs (FGF-19, FGF-21, and FGF-23) to avoid unacceptable toxicity. To achieve these design requirements, we engineered a soluble FGF receptor 1 Fc fusion protein, FP-1039. FP-1039 binds tightly to all of the mitogenic FGF ligands, inhibits FGF-stimulated cell proliferation in vitro, blocks FGF- and vascular endothelial growth factor (VEGF)-induced angiogenesis in vivo, and inhibits in vivo growth of a broad range of tumor types. FP-1039 antitumor response is positively correlated with RNA levels of FGF2, FGF18, FGFR1c, FGFR3c, and ETV4; models with genetic aberrations in the FGF pathway, including FGFR1-amplified lung cancer and FGFR2-mutated endometrial cancer, are particularly sensitive to FP-1039-mediated tumor inhibition. FP-1039 does not appreciably bind the hormonal FGFs, because these ligands require a cell surface co-receptor, klotho or β-klotho, for high-affinity binding and signaling. Serum calcium and phosphate levels, which are regulated by FGF-23, are not altered by administration of FP-1039. By selectively blocking nonhormonal FGFs, FP-1039 treatment confers antitumor efficacy without the toxicities associated with other FGF pathway inhibitors.

Biomarkers in bladder cancer: translational and clinical implications

Bladder cancer is associated with high recurrence and mortality rates. These tumors show vast heterogeneity reflected by diverse morphologic manifestations and various molecular alterations associated with these disease phenotypes. Biomarkers that prospectively evaluate disease aggressiveness, progression risk, probability of recurrence and overall prognosis would improve patient care. Integration of molecular markers with conventional pathologic staging of bladder cancers may refine clinical decision making for the selection of adjuvant and salvage therapy. In the past decade, numerous bladder cancer biomarkers have been identified, including various tumor suppressor genes, oncogenes, growth factors, growth factor receptors, hormone receptors, proliferation and apoptosis markers, cell adhesion molecules, stromal factors, and oncoproteins. Recognition of two distinct pathways for urothelial carcinogenesis represents a major advance in the understanding and management of this disease. Nomograms for combining results from multiple biomarkers have been proposed to increase the accuracy of clinical predictions. The scope of this review is to summarize the major biomarker findings that may have translational and clinical implications.

Prenatal ultrasound and molecular diagnosis elucidate the prognosis of Pfeiffer syndrome1)

Background: Pfeiffer syndrome (PS) is one of several related craniosynostosis and occurs in 1 out of every 100,000 births. The diagnosis has historically been based on the clinical neonatal findings of bilateral coronal craniosynostosis, midface hypoplasia, with broad thumbs and great toes.

Case: A craniosynostosis suggestive of PS was identified on prenatal ultrasound at 34+3 weeks gestation by findings of polyhydramnios, a cloverleaf skull, ventriculomegaly, hypertelorism, marked orbital proptosis, short limbs, broad digits, and an abnormality of the spine. Prenatal molecular testing of the FGFR genes revealed an exon 10, p.Y340C mutation in the FGFR2 gene.

Conclusion: PS can now be diagnosed prenatally. In our case, the specific mutation was associated with an especially severe phenotype. The ultrasonographic findings in conjunction with the molecular diagnosis allowed us to better inform the patient and medical staff about the diagnosis and prognosis.

Whole exome sequencing of adenoid cystic carcinoma

Adenoid cystic carcinoma (ACC) is a rare malignancy that can occur in multiple organ sites and is primarily found in the salivary gland. While the identification of recurrent fusions of the MYB-NFIB genes have begun to shed light on the molecular underpinnings, little else is known about the molecular genetics of this frequently fatal cancer. We have undertaken exome sequencing in a series of 24 ACC to further delineate the genetics of the disease. We identified multiple mutated genes that, combined, implicate chromatin deregulation in half of cases. Further, mutations were identified in known cancer genes, including PIK3CA, ATM, CDKN2A, SF3B1, SUFU, TSC1, and CYLD. Mutations in NOTCH1/2 were identified in 3 cases, and we identify the negative NOTCH signaling regulator, SPEN, as a new cancer gene in ACC with mutations in 5 cases. Finally, the identification of 3 likely activating mutations in the tyrosine kinase receptor FGFR2, analogous to those reported in ovarian and endometrial carcinoma, point to potential therapeutic avenues for a subset of cases.

Molecular mechanisms of fibroblast growth factor signaling in physiology and pathology

Fibroblast growth factors (FGFs) signal in a paracrine or endocrine fashion to mediate a myriad of biological activities, ranging from issuing developmental cues, maintaining tissue homeostasis, and regulating metabolic processes. FGFs carry out their diverse functions by binding and dimerizing FGF receptors (FGFRs) in a heparan sulfate (HS) cofactor- or Klotho coreceptor-assisted manner. The accumulated wealth of structural and biophysical data in the past decade has transformed our understanding of the mechanism of FGF signaling in human health and development, and has provided novel concepts in receptor tyrosine kinase (RTK) signaling. Among these contributions are the elucidation of HS-assisted receptor dimerization, delineation of the molecular determinants of ligand-receptor specificity, tyrosine kinase regulation, receptor cis-autoinhibition, and tyrosine trans-autophosphorylation. These structural studies have also revealed how disease-associated mutations highjack the physiological mechanisms of FGFR regulation to contribute to human diseases. In this paper, we will discuss the structurally and biophysically derived mechanisms of FGF signaling, and how the insights gained may guide the development of therapies for treatment of a diverse array of human diseases.

Protein tyrosine phosphatase variants in human hereditary disorders and disease susceptibilities

Reversible tyrosine phosphorylation of proteins is a key regulatory mechanism to steer normal development and physiological functioning of multicellular organisms. Phosphotyrosine dephosphorylation is exerted by members of the super-family of protein tyrosine phosphatase (PTP) enzymes and many play such essential roles that a wide variety of hereditary disorders and disease susceptibilities in man are caused by PTP alleles. More than two decades of PTP research has resulted in a collection of PTP genetic variants with corresponding consequences at the molecular, cellular and physiological level. Here we present a comprehensive overview of these PTP gene variants that have been linked to disease states in man. Although the findings have direct bearing for disease diagnostics and for research on disease etiology, more work is necessary to translate this into therapies that alleviate the burden of these hereditary disorders and disease susceptibilities in man.

The Current and Future Therapies for Human Osteosarcoma

Osteosarcoma (OS) is the most common non-hematologic malignant tumor of bone in adults and children. As sarcomas are more common in adolescents and young adults than most other forms of cancer, there are a significant number of years of life lost secondary to these malignancies. OS is associated with a poor prognosis secondary to a high grade at presentation, resistance to chemotherapy and a propensity to metastasize to the lungs. Current OS management involves both chemotherapy and surgery. The incorporation of cytotoxic chemotherapy into therapeutic regimens escalated cure rates from <20% to current levels of 65-75%. Furthermore, limb-salvage surgery is now offered to the majority of OS patients. Despite advances in chemotherapy and surgical techniques over the past three decades, there has been stagnation in patient survival outcome improvement, especially in patients with metastatic OS. Thus, there is a critical need to identify novel and directed therapy for OS. Several Phase I trials for sarcoma therapies currently ongoing or recently completed have shown objective responses in OS. Novel drug delivery mechanisms are currently under phase II and III clinical trials. Furthermore, there is an abundance of preclinical research which holds great promise in the development of future OS-directed therapeutics. Our continuously improving knowledge of the molecular and cell-signaling pathways involved in OS will translate into more effective therapies for OS and ultimately improved patient survival. The present review will provide an overview of current therapies, ongoing clinical trials and therapeutic targets under investigation for OS.

Fibroblast growth factor 10 in human ovaries

The expression of fibroblast growth factor 10 (FGF-10) has not been studied in human ovarian cortical follicles. The aim of the present study was to investigate the expression of FGF-10 in preantral follicles from fetuses, girls and women. Ovarian samples were obtained from 14 human fetuses at 21-33 gestational weeks and from 35 girls and women aged 5-39 years. The specimens were prepared for detection of the FGF-10 protein by immunohistochemistry. Reverse-transcription PCR was applied to ovarian extracts to identify FGF-10 mRNA transcripts. In fetal tissue, the FGF-10 protein was detected in oocytes in 50% of the samples and in granulosa cells in 30%. In ovarian tissue from girls and women, the FGF-10 protein was detected in oocytes and granulosa cells in all samples. FGF-10 mRNA transcripts were present in all adult and fetal samples tested. The identification of FGF-10 at both the protein and mRNA levels suggests that FGF-10 may contribute to human preantral follicle development.

Paternal age effect mutations and selfish spermatogonial selection: causes and consequences for human disease

Advanced paternal age has been associated with an increased risk for spontaneous congenital disorders and common complex diseases (such as some cancers, schizophrenia, and autism), but the mechanisms that mediate this effect have been poorly understood. A small group of disorders, including Apert syndrome (caused by FGFR2 mutations), achondroplasia, and thanatophoric dysplasia (FGFR3), and Costello syndrome (HRAS), which we collectively term "paternal age effect" (PAE) disorders, provides a good model to study the biological and molecular basis of this phenomenon. Recent evidence from direct quantification of PAE mutations in sperm and testes suggests that the common factor in the paternal age effect lies in the dysregulation of spermatogonial cell behavior, an effect mediated molecularly through the growth factor receptor-RAS signal transduction pathway. The data show that PAE mutations, although arising rarely, are positively selected and expand clonally in normal testes through a process akin to oncogenesis. This clonal expansion, which is likely to take place in the testes of all men, leads to the relative enrichment of mutant sperm over time-explaining the observed paternal age effect associated with these disorders-and in rare cases to the formation of testicular tumors. As regulation of RAS and other mediators of cellular proliferation and survival is important in many different biological contexts, for example during tumorigenesis, organ homeostasis and neurogenesis, the consequences of selfish mutations that hijack this process within the testis are likely to extend far beyond congenital skeletal disorders to include complex diseases, such as neurocognitive disorders and cancer predisposition.

A deletion of FGFR2 creating a chimeric IIIb/IIIc exon in a child with Apert syndrome

Background

Signalling by fibroblast growth factor receptor type 2 (FGFR2) normally involves a tissue-specific alternative splice choice between two exons (IIIb and IIIc), which generates two receptor isoforms (FGFR2b and FGFR2c respectively) with differing repertoires of FGF-binding specificity. Here we describe a unique chimeric IIIb/c exon in a patient with Apert syndrome, generated by a non-allelic homologous recombination event.

Case Presentation

We present a child with Apert syndrome in whom routine genetic testing had excluded the FGFR2 missense mutations commonly associated with this disorder. The patient was found to harbour a heterozygous 1372 bp deletion between FGFR2 exons IIIb and IIIc, apparently originating from recombination between 13 bp of identical DNA sequence present in both exons. The rearrangement was not present in the unaffected parents.

Conclusions

Based on the known pathogenesis of Apert syndrome, the chimeric FGFR2 protein is predicted to act in a dominant gain-of-function manner. This is likely to result from its expression in mesenchymal tissues, where retention of most of the residues essential for FGFR2b binding activity would result in autocrine activation. This report adds to the repertoire of rare cases of Apert syndrome for which a pathogenesis based on atypical FGFR2 rearrangements can be demonstrated.

Pictorial essay: The many faces of craniosynostosis

Craniosynostosis is a common condition in the pediatric age group, which may either be isolated or may present as part of a craniofacial syndrome. This pictorial review illustrates the underlying mechanisms and pathophysiology of craniosynostosis, the various types of craniosynostoses, common craniofacial syndromes and the role of imaging in their diagnosis and management.

Signaling networks in RUNX2-dependent bone development

RUNX2 is an essential transcription factor for osteoblast differentiation and chondrocyte maturation. SP7, another transcription factor, is required for osteoblast differentiation. Major signaling pathways, including FGF, Wnt, and IHH, also play important roles in skeletal development. RUNX2 regulates Sp7 expression at an early stage of osteoblast differentiation. FGF2 upregulates Runx2 expression and activates RUNX2, and gain-of-function mutations of FGFRs cause craniosynostosis and limb defect with upregulation of Runx2 expression. Wnt signaling upregulates Runx2 expression and activates RUNX2, and RUNX2 induces Tcf7 expression. IHH is required for Runx2 expression in osteoprogenitor cells during endochondral bone development, and RUNX2 directly regulates Ihh expression in chondrocytes. Thus, RUNX2 regulates osteoblast differentiation and chondrocyte maturation through the network with SP7 and with FGF, Wnt, and IHH signaling pathways during skeletal development.

Defective osteogenic differentiation in the development of osteosarcoma

Osteosarcoma (OS) is associated with poor prognosis due to its high incidence of metastasis and chemoresistance. It often arises in areas of rapid bone growth in long bones during the adolescent growth spurt. Although certain genetic conditions and alterations increase the risk of developing OS, the molecular pathogenesis is poorly understood. Recently, defects in differentiation have been linked to cancers, as they are associated with high cell proliferation. Treatments overcoming these defects enable terminal differentiation and subsequent tumor inhibition. OS development may be associated with defects in osteogenic differentiation. While early regulators of osteogenesis are unable to bypass these defects, late osteogenic regulators, including Runx2 and Osterix, are able to overcome some of the defects and inhibit tumor propagation through promoting osteogenic differentiation. Further understanding of the relationship between defects in osteogenic differentiation and tumor development holds tremendous potential in treating OS.

Fibroblast growth factor receptor 2 and its role in caudal appendage and craniosynostosis

Caudal appendage is a rare but reported finding seen in association with craniosynostosis. We report a newborn with caudal appendage secondary to sacrococcygeal eversion, a cloverleaf skull, choanal atresia, and a heterozygous mutation of Y375C in the juxtamembrane domain (exon 11) of fibroblast growth factor receptor 2 (FGFR2). Further support of this association are 22 other cases of craniosynostosis with caudal appendage or sacrococcygeal eversion in the literature. Of these, 19 had detectable mutations in FGFR2; 5, the same mutation; and 5, a similar substitution of cysteine for serine. We hypothesize that the association of craniosynostosis and caudal appendage is due to abnormal expression of FGFR2 in the tail bud of a developing embryo based on animal models. Our case and those reported in the literature suggest that in patients with caudal appendage and craniosynostosis, FGRF2 analysis should include regions outside the commonly tested exons 8 and 10, particularly the juxtamembrane domain.

FGF and ROR2 receptor tyrosine kinase signaling in human skeletal development

Skeletal malformations are among the most frequent developmental disturbances in humans. In the past years, progress has been made in unraveling the molecular mechanisms that govern skeletal development by the use of animal models as well as by the identification of numerous mutations that cause human skeletal syndromes. Receptor tyrosine kinases have critical roles in embryonic development. During formation of the skeletal system, the fibroblast growth factor receptor (FGFR) family plays major roles in the formation of cranial, axial, and appendicular bones. Another player of relevance to skeletal development is the unusual receptor tyrosine kinase ROR2, the function of which is as interesting as it is complex. In this chapter, we review the involvement of FGFR signaling in human skeletal disease and provide an update on the growing knowledge of ROR2.

Sculpturing digit shape by cell death

Physiological cell death is a key mechanism that ensures appropriate development and maintenance of tissues and organs in multicellular organisms. Most structures in the vertebrate embryo exhibit defined areas of cell death at precise stages of development. In this regard the areas of interdigital cell death during limb development provide a paradigmatic model of massive cell death with an evident morphogenetic role in digit morphogenesis. Physiological cell death has been proposed to occur by apoptosis, cellular phenomena genetically controlled to orchestrate cell suicide following two main pathways, cytochrome C liberation from the mitochondria or activation of death receptors. Such pathways converge in the activation of cysteine proteases known as caspases, which execute the cell death program, leading to typical morphologic changes within the cell, termed apoptosis. According to these findings it would be expected that caspases loss of function experiments could cause inhibition of interdigital cell death promoting syndactyly phenotypes. A syndactyly phenotype is characterized by absence of digit freeing during development that, when caused by absence of interdigital cell death, is accompanied by the persistence of an interdigital membrane. However this situation has not been reported in any of the KO mice or chicken loss of function experiments ever performed. Moreover histological analysis of dying cells within the interdigit reveals the synchronic occurrence of different types of cell death. All these findings are indicative of caspase alternative and/or complementary mechanisms responsible for physiological interdigital cell death. Characterization of alternative cell death pathways is required to explain vertebrate morphogenesis. Today there is great interest in cell death via autophagy, which could substitute or act synergistically to the apoptotic pathway. Here we discuss what is known about physiological cell death in the developing interdigital tissue of vertebrate embryos, paying special attention to the avian species.

Microarray analysis identifies distinct gene expression profiles associated with histological subtype in human osteosarcoma

Osteosarcoma is the most common primary malignant bone tumour. Currently osteosarcoma classification is based on histological appearance. It was the aim of this study to use a more systematic approach to osteosarcoma classification based on gene expression analysis and to identify subtype specific differentially expressed genes. We analysed the global gene expression profiles of ten osteosarcoma samples using Affymetrix U133A arrays (five osteoblastic and five non-osteoblastic osteosarcoma patients). Differential gene expression analysis yielded 75 genes up-regulated and 97 genes down-regulated in osteoblastic versus non-osteoblastic osteosarcoma samples, respectively. These included genes involved in cell growth, chemotherapy resistance, angiogenesis, steroid- and neuropeptide hormone receptor activity, acute-phase response and serotonin receptor activity and members of the Wnt/ß-catenin pathway and many others. Furthermore, we validated the highly differential expression of six genes including angiopoietin 1, IGFBP3, ferredoxin 1, BMP, decorin, and fibulin 1 in osteoblastic osteosarcoma relative to non-osteoblastic osteosarcoma. Our results show the utility of gene expression analysis to study osteosarcoma subtypes, and we identified several genes that may play a role as potential therapeutic targets in the future.

Closely spaced multiple mutations as potential signatures of transient hypermutability in human genes

Data from diverse organisms suggests that transient hypermutability is a general mutational mechanism with the potential to generate multiple synchronous mutations, a phenomenon probably best exemplified by closely spaced multiple mutations (CSMMs). Here we have attempted to extend the concept of transient hypermutability from somatic cells to the germline, using human inherited disease-causing multiple mutations as a model system. Employing stringent criteria for data inclusion, we have retrospectively identified numerous potential examples of pathogenic CSMMs that exhibit marked similarities to the CSMMs reported in other systems. These examples include (1) eight multiple mutations, each comprising three or more components within a sequence tract of <100 bp; (2) three possible instances of "mutation showers"; and (3) numerous highly informative "homocoordinate" mutations. Using the proportion of CpG substitution as a crude indicator of the relative likelihood of transient hypermutability, we present evidence to suggest that CSMMs comprising at least one pair of mutations separated by < or =100 bp may constitute signatures of transient hypermutability in human genes. Although this analysis extends the generality of the concept of transient hypermutability and provides new insights into what may be considered a novel mechanism of mutagenesis underlying human inherited disease, it has raised serious concerns regarding current practices in mutation screening.