Simpson Golabi Behmel syndrome: progress toward understanding the molecular basis for overgrowth, malformation, and cancer predisposition

Hereditary Conditions Associated with Elevated Cancer Risk in Childhood

Received January, 31, 2023 Revised March, 16, 2023 Accepted March, 18, 2023 Widespread use of the next-generation sequencing (NGS) technologies revealed that a significant percentage of tumors in children develop as a part of monogenic hereditary diseases. Predisposition to the development of pediatric neoplasms is characteristic of a wide range of conditions including hereditary tumor syndromes, primary immunodeficiencies, RASopathies, and phakomatoses. The mechanisms of tumor molecular pathogenesis are diverse and include disturbances in signaling cascades, defects in DNA repair, chromatin remodeling, and microRNA processing. Timely diagnosis of tumor-associated syndromes is important for the proper choice of cancer treatment, genetic counseling of families, and development of the surveillance programs. The review describes the spectrum of neoplasms characteristic of the most common syndromes and molecular pathogenesis of these diseases.

Stages of preadipocyte differentiation: biomarkers and pathways for extracellular structural remodeling

BACKGROUND

This study utilized bioinformatics to analyze the underlying biological mechanisms involved in adipogenic differentiation, synthesis of the extracellular matrix (ECM), and angiogenesis during preadipocyte differentiation in human Simpson-Golabi-Behmel syndrome at different time points and identify targets that can potentially improve fat graft survival.

RESULTS

We analyzed two expression profiles from the Gene Expression Omnibus and identified differentially expressed genes (DEGs) at six different time points after the initiation of preadipocyte differentiation. Related pathways were identified using Gene Ontology/Kyoto Encyclopedia of Genes and Genomes analyses and Gene Set Enrichment Analysis (GSEA). We further constructed a protein-protein interaction (PPI) network and its central genes. The results showed that upregulated DEGs were involved in cell differentiation, lipid metabolism, and other cellular activities, while downregulated DEGs were associated with angiogenesis and development, ECM tissue synthesis, and intercellular and intertissue adhesion. GSEA provided a more comprehensive basis, including participation in and positive regulation of key pathways of cell metabolic differentiation, such as the "peroxisome proliferator-activated receptor signaling pathway" and the "adenylate-activated protein kinase signaling pathway," a key pathway that negatively regulates pro-angiogenic development, ECM synthesis, and adhesion.

CONCLUSIONS

We identified the top 20 hub genes in the PPI network, including genes involved in cell differentiation, ECM synthesis, and angiogenesis development, providing potential targets to improve the long-term survival rate of fat grafts. Additionally, we identified drugs that may interact with these targets to potentially improve fat graft survival.

Heparan Sulfate Proteoglycans Biosynthesis and Post Synthesis Mechanisms Combine Few Enzymes and Few Core Proteins to Generate Extensive Structural and Functional Diversity

Glycosylation is a common and widespread post-translational modification that affects a large majority of proteins. Of these, a small minority, about 20, are specifically modified by the addition of heparan sulfate, a linear polysaccharide from the glycosaminoglycan family. The resulting molecules, heparan sulfate proteoglycans, nevertheless play a fundamental role in most biological functions by interacting with a myriad of proteins. This large functional repertoire stems from the ubiquitous presence of these molecules within the tissue and a tremendous structural variety of the heparan sulfate chains, generated through both biosynthesis and post synthesis mechanisms. The present review focusses on how proteoglycans are “gagosylated” and acquire structural complexity through the concerted action of Golgi-localized biosynthesis enzymes and extracellular modifying enzymes. It examines, in particular, the possibility that these enzymes form complexes of different modes of organization, leading to the synthesis of various oligosaccharide sequences.

Glypican-3 expression in malignant small round cell tumors

Malignant small round cell tumors usually progress rapidly and show resistance to chemotherapy, and it is often difficult to make a definitive diagnosis based on their histological morphology. Glypican-3 (GPC3) is a highly tumor-specific antigen, and the overexpression of GPC3 was reported in many pediatric and adult malignancies. In the present study, we investigated the GPC3 expression in pediatric malignant small round cell tumors to assess its role in the differential diagnosis of the tumors. Immunohistochemistry was performed to assess the expression of GPC3 in samples from 84 rhabdomyosarcomas (RMSs; 44 alveolar and 40 embryonal RMSs), 62 Ewing sarcomas (EWSs), 35 neuroblastomas (NBs) and two desmoplastic small round cell tumors (DSRCTs). We performed a reverse transcription-quantitative polymerase chain reaction for GPC3 to determine the GPC3 mRNA expression in samples from 66 frozen tumors (23 RMSs, 28 EWSs and 15 NBs). The serum expression levels of GPC3 were analyzed in pre-operative blood samples from two RMS and eight NB patients. In total, 25% (21/84) of the RMSs and 3% (1/35) of the NBs exhibited a focal expression of GPC3, whereas, the other specimens showed no GPC3 expression. The GPC3 mRNA expression level of the RMSs with positive GPC3 expression (n=6) was significantly higher compared with the RMSs without such expression (n=17). A total of two cases of NB showed high serum levels of GPC3, but neither tumor showed immunoreactivity for GPC3. The immunohistochemical overexpression of GPC3 may be a candidate ancillary parameter in the differential diagnosis of RMS from EWS and DSRCT.

Tall Stature: A Challenge for Clinicians

Clinicians generally use the term "tall stature" to define a height more than two standard deviations above the mean for age and sex. In most cases, these subjects present with familial tall stature or a constitutional advance of growth which is diagnosed by excluding the other conditions associated with overgrowth. Nevertheless, it is necessary to be able to identify situations in which tall stature or an accelerated growth rate indicate an underlying disorder. A careful physical evaluation allows the classification of tall patients into two groups: those with a normal appearance and those with an abnormal appearance including disproportion or dysmorphism. In the first case, the growth rate has to be evaluated and, if it is normal for age and sex, the subjects may be considered as having familial tall stature or constitutional advance of growth or they may be obese, while if the growth rate is increased, pubertal status and thyroid function should be evaluated. In turn, tall subjects having an abnormal appearance can be divided into proportionate and disproportionate syndromic patients. Before initiating further investigations, the clinician needs to perform both a careful physical examination and growth evaluation. To exclude pathological conditions, the cause of tall stature needs to be considered, although most children are healthy and generally do not require treatment to inhibit growth progression. In particular cases, familial tall stature subject can be treated by inducing puberty early and leading to a complete fusion of the epiphyses, so final height is reached. This review aims to provide proposals about the management of tall children.

Identification of Glypican-3 as a potential metastasis suppressor gene in gastric cancer

Gastric cancer is a prevalent tumor that is usually detected at an advanced metastatic stage. Currently, standard therapies are mostly ineffective. Here, we report that Glypican-3 (GPC3) is absent in invasive tumors and metastatic lymph nodes, in particular in aggressive and highly disseminated signet ring cell carcinomas. We demonstrate that loss of GPC3 correlates with poor overall survival in patients. Moreover, we show that absence of GPC3 causes up-regulation of MAPK/FoxM1 signaling and that blockade of this pathway alters cellular invasion. An inverse correlation between GPC3 and FoxM1 is also shown in patient samples. These data identify GPC3 as a potential metastasis suppressor gene and suggest its value as a prognostic marker in gastric cancer. Development of therapies targeting signaling downstream of GPC3 are warranted.

Tall stature: a difficult diagnosis?

Referral for an assessment of tall stature is less common than for short stature. Tall stature is defined as a height more than two standard deviations above the mean for age. The majority of subjects with tall stature show a familial tall stature or a constitutional advance of growth (CAG), which is a diagnosis of exclusion. After a careful physical evaluation, tall subjects may be divided into two groups: tall subjects with normal appearance and tall subjects with abnormal appearance. In the case of normal appearance, the paediatric endocrinologist will have to evaluate the growth rate. If it is normal for age and sex, the subject may be classified as having familial tall stature, CAG or obese subject, while if the growth rate is increased it is essential to evaluate pubertal status and thyroid status. Tall subjects with abnormal appearance and dysmorphisms can be classified into those with proportionate and disproportionate syndromes.

A careful physical examination and an evaluation of growth pattern are required before starting further investigations. Physicians should always search for a pathological cause of tall stature, although the majority of children are healthy and they generally do not need treatment to cease growth progression.

The most accepted and effective treatment for an excessive height prediction is inducing puberty early and leading to a complete fusion of the epiphyses and achievement of final height, using testosterone in males and oestrogens in females. Alternatively, the most common surgical procedure for reducing growth is bilateral percutaneous epiphysiodesis of the distal femur and proximal tibia and fibula.

This review aims to provide up-to-date information and suggestions about the diagnosis and management of children with tall stature.

SGBS cells as a model of human adipocyte browning: A comprehensive comparative study with primary human white subcutaneous adipocytes

The Simpson Golabi Behmel Syndrome (SGBS) pre-adipocyte cell strain is widely considered to be a representative in vitro model of human white pre-adipocytes. A recent study suggested that SGBS adipocytes exhibit an unexpected transient brown phenotype. Here, we comprehensively examined key differences between SGBS adipocytes and primary human white subcutaneous (PHWSC) adipocytes. RNA-Seq analysis revealed that extracellular matrix (ECM)-receptor interaction and metabolic pathways were the top two KEGG pathways significantly enriched in SGBS adipocytes, which included positively enriched mitochondrial respiration and oxidation pathways. Compared to PHWSC adipocytes, SGBS adipocytes showed not only greater induction of adipogenic gene expression during differentiation but also increased levels of UCP1 mRNA and protein expression. Functionally, SGBS adipocytes displayed higher ISO-induced basal leak respiration and overall oxygen consumption rate, along with increased triglyceride accumulation and insulin-stimulated glucose uptake. In conclusion, we confirmed that SGBS adipocytes, which are considered of white adipose tissue origin can shift towards a brown/beige adipocyte phenotype. These differences indicate SGBS cells may help to identify mechanisms leading to browning, and inform our understanding for the use of SGBS vis-à-vis primary human subcutaneous adipocytes as a human white adipocyte model, guiding the selection of appropriate cell models in future metabolic research.

Biology and function of glypican-3 as a candidate for early cancerous transformation of hepatocytes in hepatocellular carcinoma (Review)

Glypican-3 (GPC-3), a transmembrane heparan sulfate proteoglycan (HSPG), has recently been investigated as a player in tissue-dependent cellular signaling, specifically as a regulator of growth. Noteworthy, the regulatory protein has been implicated in both stimulatory and inhibitory pathways involving cell growth. Initially, GPC-3 was thought to act as a cell cycle regulator, as a loss-of-function mutation in the gene caused a hyper-proliferative state known as Simpson-Golabi-Behmel (SGB) overgrowth syndrome. Additionally, certain cancer types have displayed a downregulation of GPC-3 expression. More recently, the protein has been evaluated as a useful marker for hepatocellular carcinoma (HCC) due to its increased expression in the liver during times of growth. In contrast, the GPC-3 marker is not detectable in normal adult liver. Immunotherapy that targets GPC-3 and its affiliated proteins is under investigation as these new biomarkers may hold potential for the detection and treatment of HCC and other diseases in which GPC-3 may be overexpressed. Studies have reported that an overexpression of GPC-3 in HCC predicts a poorer prognosis. This prognostic value further pushes the question regarding GPC-3's role in the regulation and progression of HCC. This review will summarize the current knowledge regarding the clinical aspects of GPC-3, while also synthesizing the current literature with the aim to better understand this molecule's biological interactions at a molecular level, not only in the liver, but in the rest of the body as well. Due to the existing gap in the literature surrounding GPC-3, we believe further investigation of function, structure and domains, cellular localization, and other subfields is warranted to evaluate the protein as a whole, as well as its part in the study of HCC.

Adoptive immunotherapy using T lymphocytes redirected to glypican-3 for the treatment of lung squamous cell carcinoma

There are unmet medical needs for patients with lung squamous cell carcinoma (LSCC). Therefore, in this study, we explored the antitumor potential of third-generation glypican 3 (GPC3)-redirected chimeric antigen receptor (CAR)-engineered T lymphocytes (CARgpc3 T cells) in tumor models of LSCC. First, we demonstrated by immunohistochemistry (IHC) that GPC3 was expressed in 66.3% of LSCC samples and in 3.3% of lung adenocarcinoma (LAD) samples but not in normal lung tissues. In the presence of GPC3-positive LSCC cells, CARgpc3 T cells were highly activated and increased in number. CARgpc3 T cells could specifically lyse GPC3-positive LSCC cells in vitro. In two established LSCC xenograft models, CARgpc3 T cells could almost completely eliminate the growth of GPC3-positive cells. Additionally, the CARgpc3 T cells were able to persist in vivo and efficiently infiltrate the cancerous tissues. Taken together, these findings indicate that CARgpc3 T cells might be a novel potential therapeutic agent for the treatment of patients with LSCC.

Whole exome sequencing and array-based molecular karyotyping as aids to prenatal diagnosis in fetuses with suspected Simpson-Golabi-Behmel syndrome

OBJECTIVE

Simpson-Golabi-Behmel (SGBS) syndrome type 1 and type 2 represent rare X-linked prenatal overgrowth disorders. The aim of our study is to describe the prenatal sonographic features as well as the genetic work-up.

METHOD

Retrospective analysis of four cases with a pre- or postnatal diagnosis of SGBS in a single tertiary referral center within a period of 4 years.

RESULTS

In the study period, four male fetuses with SGBS were detected. The final diagnosis was made prenatally in three cases. In all cases the second trimester anomaly scan revealed left sided congenital diaphragmatic hernia (CDH) with additional anomalies; three fetuses with SGBS type 1 showed fetal overgrowth. In two of these, whole exome sequencing showed a possible frameshift mutation and a point mutation in the gene GPC3, respectively. In the third case, multiplex ligation-dependent probe amplification (MLPA) revealed a hemizygous duplication of exon 3-7 in the gene GPC3. In the fourth case, SGBS type 2 was confirmed by array comparative genomic hybridization (CGH) of amniotic fluid cells showing a deletion of the gene OFD1.

CONCLUSION

We could demonstrate, that in the presence of a CDH, syndromes of the fetus can be increasingly differentiated by detailed sonography followed by a selective and graded molecular diagnostic using microarray techniques and whole exome sequencing. © 2016 John Wiley & Sons, Ltd.

Expression of Glypican-4 in the brains of epileptic patients and epileptic animals and its effects on epileptic seizures

Glypican-4 (Gpc4) has been found to play an important role in enhancing miniature excitatory postsynaptic currents (mEPSCs). But, the relationship between Gpc4 and epilepsy is still a mystery. In this study, we investigated the expression patterns of Gpc4 in patients with epilepsy and in a pilocarpine-induced rat model of epilepsy. We also determined if altered Gpc4 expression resulted in increased susceptibility to seizures. Western blotting and immunofluorescent methods were utilized. Gpc4 was significantly increased in patients and epileptic rats induced by pilocarpine injection. According to behavioral studies, downregulation of Gpc4 by Gpc4 siRNA decreased spontaneous seizure frequency, while upregulation of Gpc4 by recombinant Gpc4 overexpression led to a converse result. These findings support the hypothesis that increased expression of Gpc4 in the brain is associated with epileptic seizures.

Synchronous Hepatoblastoma, Neuroblastoma, and Cutaneous Capillary Hemangiomas: A Case Report

Multiple synchronous tumors presenting in infancy raise concern for inherited or sporadic cancer predisposition syndromes, which include Beckwith-Wiedemann syndrome, familial adenomatous polyposis syndrome, and Li-Fraumeni syndrome. We report a case of a 7-month-old previously healthy male born following an in vitro fertilization-assisted twin pregnancy who presented with new-onset refractory shock, severe acidosis, and rapid decline over several hours. An autopsy revealed a ruptured liver involved by hepatoblastoma, an adrenal gland involved by neuroblastoma, and multiple cutaneous capillary hemangiomas. Standard genetic testing demonstrated that both twins were Gaucher disease (GD) carriers without evidence of other known cancer predisposition syndromes. This report describes a unique association of multiple synchronous tumors, which underscores the utility and importance of the pediatric autopsy. Moreover, given that the reported child was a GD carrier, the possibility the tumors were the result of a GD-mediated cancer-associated phenotype or an unrecognized sporadic clinical syndrome remains an unanswered, but intriguing, question worthy of further investigation.

Generalized overgrowth syndromes with prenatal onset

Children with generalized overgrowth syndromes are large at birth, or have excessive postnatal growth. Many of these syndromes are associated with an increase in neoplasia. Consideration of the possibility of overgrowth syndrome in a pediatric patient who presents with increased growth parameters, variable malformations and neurodevelopmental phenotype, and distinctive features, is important for medical management, reproductive counseling, and tumor surveillance for some of the disorders. This review describes the clinical features and surveillance recommendations for the common generalized overgrowth syndromes the pediatrician may encounter. It also provides a glimpse into advances of recent years in understanding the molecular mechanisms responsible for the disrupted growth regulation in these disorders.

A matrix metalloproteinase mediates long-distance attenuation of stem cell proliferation

Long-range signaling by Wingless in the Drosophila ovary requires the glypican Dally-like and is antagonized by Dally-like cleavage by the extracellular metalloproteinase Mmp2.

Ligand-based signaling can potentiate communication between neighboring cells and between cells separated by large distances. In the Drosophila melanogaster ovary, Wingless (Wg) promotes proliferation of follicle stem cells located ∼50 µm or five cell diameters away from the Wg source. How Wg traverses this distance is unclear. We find that this long-range signaling requires Division abnormally delayed (Dally)-like (Dlp), a glypican known to extend the range of Wg ligand in the wing disc by binding Wg. Dlp-mediated spreading of Wg to follicle stem cells is opposed by the extracellular protease Mmp2, which cleaved Dlp in cell culture, triggering its relocalization such that Dlp no longer contacted Wg protein. Mmp2-deficient ovaries displayed increased Wg distribution, activity, and stem cell proliferation. Mmp2 protein is expressed in the same cells that produce Wg; thus, niche cells produce both a long-range stem cell proliferation factor and a negative regulator of its spreading. This system could allow for spatial control of Wg signaling to targets at different distances from the source.

Efficacy of neoadjuvant therapy and surgical rescue for locally advanced hepatoblastomas: 10 year single-center experience and literature review

AIM: To report our experience with long-term outcomes after multimodal management therapy.

METHODS: An observational retrospective study was performed containing seven patients with hepatoblastoma (Hbl) treated in our institution, a tertiary referral center, from 2003 to 2011. Demographic, preoperative, surgical, and outcome variables were collected. A survival analysis and a review of the current literature related to combination neoadjuvant chemotherapy and surgical resection on Hbl were performed.

RESULTS: The median age at surgery was 14.4 mo, with a male to female ratio of 4:3. Pretext staging at diagnosis was as follows: stage I, 4 cases; stage II, 2 patients; and stage III, 1 case. Mean pretreatment tumor volume was 735 cm³. Five out of seven patients received neoadjuvant chemotherapy according to SIOPEL-3 or SIOPEL-6 protocols. Tumor volume and alpha-fetoprotein levels significantly dropped after neoadjuvant therapy. Surgical procedures performed included hemihepatectomies, segmentectomies and atypical resection. All patients received chemotherapy after surgery. Median postoperative hospital stay was 8 d. All patients were alive and disease-free after a median follow-up period of 23 mo. With regards to the literature review, seventeen articles were found that were related to our search.

CONCLUSION: Our series shows how multimodal management of Hbl, exhaustive control and a meticulous surgical approach leads to almost 100% complete resection with optimal postoperative results.

Heparan sulfate deficiency disrupts developmental angiogenesis and causes congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common birth malformation with a heterogeneous etiology. In this study, we report that ablation of the heparan sulfate biosynthetic enzyme NDST1 in murine endothelium (Ndst1ECKO mice) disrupted vascular development in the diaphragm, which led to hypoxia as well as subsequent diaphragm hypoplasia and CDH. Intriguingly, the phenotypes displayed in Ndst1ECKO mice resembled the developmental defects observed in slit homolog 3 (Slit3) knockout mice. Furthermore, introduction of a heterozygous mutation in roundabout homolog 4 (Robo4), the gene encoding the cognate receptor of SLIT3, aggravated the defect in vascular development in the diaphragm and CDH. NDST1 deficiency diminished SLIT3, but not ROBO4, binding to endothelial heparan sulfate and attenuated EC migration and in vivo neovascularization normally elicited by SLIT3-ROBO4 signaling. Together, these data suggest that heparan sulfate presentation of SLIT3 to ROBO4 facilitates initiation of this signaling cascade. Thus, our results demonstrate that loss of NDST1 causes defective diaphragm vascular development and CDH and that heparan sulfate facilitates angiogenic SLIT3-ROBO4 signaling during vascular development.

Frequency of WT1 and 11p15 constitutional aberrations and phenotypic correlation in childhood Wilms tumour patients

INTRODUCTION

In 9-17% of Wilms tumour patients a predisposing syndrome is present, in particular WT1-associated syndromes and overgrowth syndromes. Constitutional WT1 mutations or epigenetic changes on chromosome 11p15 have also been described in Wilms tumour patients without phenotypic abnormalities. Thus, the absence of phenotypic abnormalities does not exclude the presence of a genetic predisposition, suggesting that more Wilms tumour patients may have a constitutional abnormality. Therefore, we investigated the frequency of constitutional aberrations in combination with phenotype.

PATIENTS & METHODS

Clinical genetic assessment, as well as molecular analysis of WT1 and locus 11p15 was offered to a single-centre cohort of 109 childhood Wilms tumour patients.

RESULTS

Twelve patients (11%) had a WT1 aberration and eight patients (8%) had an 11p15 aberration. Of the 12 patients with a WT1 aberration, four had WAGR syndrome (Wilms tumor, aniridia, genitourinary malformations and mental retardation), one had Denys-Drash syndrome, four had genitourinary anomalies without other syndromic features and three had bilateral disease with stromal-predominant histology at young age without congenital anomalies. Of the eight patients with an 11p15 aberration, four had Beckwith-Wiedemann syndrome (BWS), two had minor features of BWS and two had no stigmata of BWS or hemihypertrophy.

CONCLUSION

Constitutional WT1 or 11p15 aberrations are frequent in Wilms tumour patients and careful clinical assessment can identify the majority of these patients. Therefore, we would recommend offering clinical genetic counselling to all Wilms tumour patients, as well as molecular analysis to patients with clinical signs of a syndrome or with features that may indicate a constitutional WT1 or 11p15 aberration.

Sostdc1 defines the size and number of skin appendage placodes

Mammary glands and hair follicles develop as ectodermal organs sharing common features during embryonic morphogenesis. The molecular signals controlling the initiation and patterning of skin appendages involve the bone morphogenetic proteins and Wnt family members, which are commonly thought to serve as inhibitory and activating cues, respectively. Here, we have examined the role of the Bmp and Wnt pathway modulator Sostdc1 in mammary gland, and hair and vibrissa follicle development using Sostdc1-null mice. Contrary to previous speculations, loss of Sostdc1 did not affect pelage hair cycling. Instead, we found that Sostdc1 limits the number of developing vibrissae and other muzzle hair follicles, and the size of primary hair placodes. Sostdc1 controls also the size and shape of mammary buds. Furthermore, Sostdc1 is essential for suppression of hair follicle fate in the normally hairless nipple epidermis, but its loss also promotes the appearance of supernumerary nipple-like protrusions. Our data suggest that functions of Sostdc1 can be largely attributed to its ability to attenuate Wnt/β-catenin signaling.

Heparin-like heparan sulfate from rabbit cartilage

Glycosaminoglycans were extracted from both young rabbit growth plate (GRP) and articular (ART) cartilage tissues and enzymatically treated to selectively eliminate chondroitin sulfates and hyaluronic acid. The procedure avoided any fractionation step that could enrich the extract with over- or under-sulfated species. Isolated heparan sulfate (HS) was characterized by mono- and bidimensional nuclear magnetic resonance (NMR) spectroscopy to quantify their specific structural features and/or by mass spectrometry to establish the disaccharide composition. Both GRP and ART HSs, despite differing in their yield (GRP at least 100 times greater than ART), exhibited a surprisingly high degree of sulfation. Quantitative two-dimensional heteronuclear single-quantum coherence-NMR analysis of GRP HS revealed unusually high N-sulfated glucosamine and 2-O-sulfated iduronic acid contents, similar to heparin. The unique pentasaccharide sequence of the binding site for antithrombin was also detected in a significant amount. High-performance liquid chromatography mass spectrometry analysis of the enzymatic digests with a cocktail of heparin lyases of both cartilaginous HSs confirmed the NMR results. As well as the discovery of an unusual HS structure in the two different types of rabbit cartilage, the feasibility of the analytical method adopted here has been demonstrated within this study. Such a method can be used to isolate and analyze HS from both normal and pathologic tissues. Characterization of healthy and pathological HS structures will contribute to improve the understanding of diseases related to malfunctions of HS biosynthesis and/or metabolism.

Array comparative genomic hybridization analysis in patients with anophthalmia, microphthalmia, and coloboma

PURPOSE

The goal of our study was to determine whether genomic copy number abnormalities (deletions and duplications) affecting genes involved in eye development contributed to the etiology of anophthalmia, microphthalmia, and coloboma.

METHODS

The affected individuals were evaluated for the presence of deletions and duplications in genomic DNA by a very high-resolution array comparative genomic hybridization.

RESULTS

Array analysis of 32 patients detected one case with a deletion encompassing the renal-coloboma syndrome associated gene PAX2. Nonpolymorphic copy number changes were also observed at several candidate chromosomal regions, including 6p12.3, 8q23.1q23.2, 13q31.3, 15q11.2q13.1, 16p13.13, and 20q13.13.

CONCLUSIONS

This study identified the first patient with the typical phenotype of the renal-coloboma syndrome caused by a submicroscopic deletion of the coding region of the PAX2 gene. The finding suggests that PAX2 deletion testing should be performed in addition to gene sequencing as a part of molecular evaluation for the renal-coloboma syndrome. Array comparative genomic hybridization testing of 32 affected individuals showed that genomic deletions and duplications are not a common cause of nonsyndromic anophthalmia, microphthalmia, or coloboma but undoubtedly contribute to the etiology of these eye anomalies. Therefore, array comparative genomic hybridization testing represents an important and valuable addition to candidate gene sequencing in research and diagnostics of ocular birth defects.

Extracellular matrix and heart development

The extracellular matrix (ECM) of the developing heart contains numerous molecules that form a dynamic environment that plays an active and crucial role in the regulation of cellular events. ECM molecules found in the heart include hyaluronan, fibronectin, fibrillin, proteoglycans, and collagens. Tight regulation of the spatiotemporal expression, and the proteolytic processing of ECM components by proteases including members of the ADAMTS family, is essential for normal cardiac development. Perturbation of the expression of genes involved in matrix composition and remodeling can interfere with a myriad of events involved in the formation of the four-chambered heart and result in prenatal lethality or cardiac malformations as seen in humans with congenital heart disease. In this review, we summarize what is known about the specific importance of some of the components of the ECM in relation to the cardiovascular development.

Fine-tuning of cell signaling by glypicans

Signaling peptides of the extracellular environment regulate cell biological processes underlying embryonic development, tissue homeostasis, and pathophysiology. The heparan sulphate proteoglycans, glypicans, have evolved as essential modulators of key regulatory proteins such as Wnt, Bmp, Fgf, and Shh. By acting on signal spreading and receptor activation, glypicans can control signal read-out and fate in targeted cells. Genetic and embryological studies have highlighted that glypicans act in a temporal and spatially regulated manner to modulate distinct cellular events. However, alterations of glypican function underlie human congenital malformations and cancer. Recent reports are starting to reveal their mechanism of action and how they can ensure tight modulation of cell signaling.

Inherited cancer syndromes in children and young adults

Geneticists estimate that 5% to 10% of all cancers diagnosed in the pediatric age range occur in children born with a genetic mutation that directly increases their lifetime risk for neoplasia. However, despite the fact that only a fraction of cancers in children occur as a result of an identified inherited predisposition, characterizing genetic mutations responsible for increased cancer risk in such syndromes has resulted in a profound understanding of relevant molecular pathways involved in carcinogenesis and/or resistance to neoplasia. Importantly, because most cancer predisposition syndromes result in an increased risk of a small number of defined malignancies, personalized prophylactic surveillance and preventive measures can be implemented in affected patients. Lastly, many of the same genetic targets identified from cancer-prone families are mechanistically involved in the majority of sporadic cancers in adults and children, thereby underscoring the clinical relevance of knowledge gained from these defined syndromes and introducing novel therapeutic opportunities to the broader oncologic community. This review highlights the clinical and genetic features of many of the known constitutional genetic syndromes that predispose to malignancy in children and young adults.

A microarray analysis of the XX Wnt4 mutant gonad targeted at the identification of genes involved in testis vascular differentiation

One of the earliest morphological changes during testicular differentiation is the establishment of an XY specific vasculature. The testis vascular system is derived from mesonephric endothelial cells that migrate into the gonad. In the XX gonad, mesonephric cell migration and testis vascular development are inhibited by WNT4 signaling. In Wnt4 mutant XX gonads, endothelial cells migrate from the mesonephros and form a male-like coelomic vessel. Interestingly, this process occurs in the absence of other obvious features of testis differentiation, suggesting that Wnt4 specifically inhibits XY vascular development. Consequently, the XX Wnt4 mutant mice presented an opportunity to focus a gene expression screen on the processes of mesonephric cell migration and testicular vascular development. We compared differences in gene expression between XY Wnt4+/+ and XX Wnt4+/+ gonads and between XX Wnt4-/- and XX Wnt4+/+ gonads to identify sets of genes similarly upregulated in wildtype XY gonads and XX mutant gonads or upregulated in XX gonads as compared to XY gonads and XX mutant gonads. We show that several genes identified in the first set are expressed in vascular domains, and have predicted functions related to cell migration or vascular development. However, the expression patterns and known functions of other genes are not consistent with roles in these processes. This screen has identified candidates for regulation of sex specific vascular development, and has implicated a role for WNT4 signaling in the development of Sertoli and germ cell lineages not immediately obvious from previous phenotypic analyses.

[Multicystic dysplastic kidney disease: update and information for parents at the time of prenatal diagnosis]

Multicystic kidney disease (MCKD) is the most common form of Congenital Abnormality of Kidney and Urinary Tract (CAKUT). This anomaly of renal development is characterized by unilateral enlarged cystic formations and fibrous dysplastic parenchyma. The long-term prognosis is usually good; however because of reduced nephron mass, an early prevention of cardiovascular risk and nephrotoxicity is recommended. A lifelong follow-up of blood pressure, serum creatinine and microalbuminuria seems logical as well as in other patients with a single kidney. MCKD is usually diagnosed during pregnancy so that parents often question about long-term prognosis and follow-up. Therefore, we propose an information sheet for parents.

Human SGBS cells - a unique tool for studies of human fat cell biology

The human Simpson-Golabi-Behmel syndrome (SGBS) preadipocyte cell strain provides a unique and useful tool for studies of human adipocyte biology. The cells originate from an adipose tissue specimen of a patient with SGBS. They are neither transformed nor immortalized, and provide an almost unlimited source due to their ability to proliferate for up to 50 generations with retained capacity for adipogenic differentiation. So far, the cells have been used for a number of studies on adipose differentiation, adipocyte glucose uptake, lipolysis, apoptosis, regulation of expression of adipokines, and protein translocation. The cells are efficiently differentiated in the presence of PPARgammaagonists and in the absence of serum and albumin. SGBS adipocytes respond to insulin stimulation by increasing glucose uptake several-fold (EC50 approximately 100 pmol/l), and by very effectively inhibiting (IC50 approximately 10 pmol/l) catecholamine-stimulated lipolysis.

Expression of glypican 3 in hepatoblastoma: an immunohistochemical study of 65 cases

Glypican 3 is a heparin sulfate proteoglycan bound to the cell surface that is theorized to participate in cell signaling, resulting in embryonic cell growth and differentiation. The GPC3 gene is mutated in Simpson-Golabi-Behmel syndrome, whose features include numerous developmental abnormalities, tissue overgrowth, and an increased risk for embryonal malignancies, including hepatoblastoma. GPC3 has been detected in hepatic stem cells and was recently identified as one of the most overexpressed genes in hepatoblastoma by microarray analysis. The purpose of this study was to analyze the expression of GPC3 in a large series of hepatoblastoma using immunohistochemistry to assess its use as a diagnostic marker. The GPC3 immunoreactivity was semiquantitatively evaluated in 65 cases of hepatoblastoma. In addition, histologic patterns in each tumor were individually assessed for immunoreactivity. All 65 hepatoblastomas had cytoplasmic immunoreactivity for GPC3 with greater than 90% of cases showing strong, diffuse positivity. There was no reactivity in benign liver tissue. Fetal, embryonal, and small cell undifferentiated patterns were diffusely positive in almost all cases, whereas mesenchymal and teratoid patterns were nearly all negative. The high GPC3 expression consistently demonstrated in this study suggests that GPC3 may play a role in the tumorigenesis of hepatoblastoma.

Single gene disorders associated with congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common birth defect with a high pre- and postnatal mortality. Although the majority of diaphragmatic hernias occur as isolated malformations, additional major and minor anomalies are common and are present in more than 40% of patients. There are compelling data for the importance of genetic factors in the etiology of CDH, but the pathogenesis and the causative genes for CDH in humans remain elusive. There are more than 70 syndromes in which diaphragmatic hernias have been described, and several of these syndromes are single gene disorders for which the gene is known. One method for identifying the causative genes in isolated CDH is to study syndromes with known genes in which CDH is a recognized feature, with the rationale that those genes have a role in diaphragm development. This review discusses the syndromes that are most commonly associated with CDH, with greater attention towards syndromes in which the causative genes have been identified, including Simpson-Golabi-Behmel syndrome, Denys-Drash syndrome, spondylocostal dysostosis, craniofrontonasal syndrome, Cornelia de Lange syndrome and Marfan syndrome.

Glypican LON-2 is a conserved negative regulator of BMP-like signaling in Caenorhabditis elegans

Bone morphogenetic protein (BMP) pathways are required for a wide variety of developmental and homeostatic decisions, and mutations in signaling components are associated with several diseases. An important aspect of BMP control is the extracellular regulation of these pathways. We show that LON-2 negatively regulates a BMP-like signaling pathway that controls body length in C. elegans. lon-2 acts genetically upstream of the BMP-like gene dbl-1, and loss of lon-2 function results in animals that are longer than normal. LON-2 is a conserved member of the glypican family of heparan sulfate proteoglycans, a family with several members known to regulate growth-factor signaling in many organisms. LON-2 is functionally conserved because the Drosophila glypican gene dally rescues the lon-2(lf) body-size defect. We show that the LON-2 protein binds BMP2 in vitro, and a mutant variation of LON-2 found in lon-2(e2140) animals diminishes this interaction. We propose that LON-2 binding to DBL-1 negatively regulates this pathway in C. elegans by attenuating ligand-receptor interactions. This is the first report of a glypican directly interacting with a growth-factor pathway in C. elegans and provides a mechanistic model for glypican regulation of growth-factor pathways.

Allogeneic transplantation and the risk for transmission of genetic disease: the heritable cancer disorders

With the development of new approaches to transplantation therapy, such as those building upon the potential found in stem cells, it is vital to pursue a clear understanding of transplantation risks. Allogeneic transplantation presents risk for the transmission of disease of various types, including genetic disease. Predisposition to develop cancer is a feature of numerous genetic disorders, and it may be transmissible by transplantation. Some genetic disorders predisposing to cancer are remarkably common, either worldwide or in specific populations, and they could pose significant risk. Hence, to reduce risk to recipients, there is reason to exclude from donation those potential donors (including embryos) harboring certain germ-line mutations. However, the frequent absence of readily identifiable features might confound the effort to exclude those who harbor mutation. Thus, it is also important to consider the magnitude of risk that they represent. For some disorders, life-threatening cancer is highly likely to develop in those individuals born with germ-line mutation, but whether recipients would face the same risk from transplanted mutation is not always evident. Given the diversity of pathways that lead to cancer, there may be diverse factors that impact the likelihood for cancer to develop in the recipient, with some factors decreasing and others increasing the risk. One factor of special concern is the possibility that manipulation of donor cells, prior to transplantation, might introduce additional genetic or epigenetic abnormality, thereby increasing the risk.

Molecular genetics of congenital diaphragmatic defects

Congenital diaphragmatic hernia (CDH) is a severe birth defect that is accompanied by malformations of the lung, heart, testis, and other organs. Patients with CDH may have any combination of these extradiaphragmatic defects, suggesting that CDH is often a manifestation of a global embryopathy. This review highlights recent advances in human and mouse genetics that have led to the identification of genes involved in CDH. These include genes for transcription factors, molecules involved in cell migration, and extracellular matrix components. The expression patterns of these genes in the developing embryo suggest that mesenchymal cell function is compromised in the diaphragm and other affected organs in patients with CDH. We discuss potential mechanisms underlying the seemingly random combination of diaphragmatic, pulmonary, cardiovascular, and gonadal defects in these patients.

Glypicans are differentially expressed during patterning and neurogenesis of early mouse brain

Glypicans are essential modulators of cell signalling during embryogenesis. Little is known about their functions in brain development. We show here that mouse glypicans (gpc-1 to gpc-6) are differentially expressed in embryonic brains during key morphogenetic events. In gastrulating embryos, gpc-4 is the only glypican expressed in anterior visceral endoderm. During neural tube closure, gpc-4 transcripts are restricted to the anterior neural ridge and telencephalon. At this stage, gpc-1 expression shifts from trunk and head mesenchyme to neural tube. Gpc-3 mRNA appears across the ventral neural tube, then in the lamina terminalis and hypothalamus. Gpc-2 and gpc-6 transcripts are in all brain compartments. Gpc-5 is found in ventral brains as neurogenesis starts. Onset of neurogenesis also coincides with differential expression of glypican genes either in neural progenitors or in differentiating neurons. The novel expression sites of glypicans shown here contribute to the identification of signalling molecules involved in brain patterning.

A microarray analysis of the XX Wnt4 mutant gonad targeted at the identification of genes involved in testis vascular differentiation

One of the earliest morphological changes during testicular differentiation is the establishment of an XY specific vasculature. The testis vascular system is derived from mesonephric endothelial cells that migrate into the gonad. In the XX gonad, mesonephric cell migration and testis vascular development are inhibited by WNT4 signaling. In Wnt4 mutant XX gonads, endothelial cells migrate from the mesonephros and form a male-like coelomic vessel. Interestingly, this process occurs in the absence of other obvious features of testis differentiation, suggesting that Wnt4 specifically inhibits XY vascular development. Consequently, the XX Wnt4 mutant mice presented an opportunity to focus a gene expression screen on the processes of mesonephric cell migration and testicular vascular development. We compared differences in gene expression between XY Wnt4+/+ and XX Wnt4+/+ gonads and between XX Wnt4+/+ and XX Wnt4+/+ gonads to identify sets of genes similarly upregulated in wildtype XY gonads and XX mutant gonads or upregulated in XX gonads as compared to XY gonads and XX mutant gonads. We show that several genes identified in the first set are expressed in vascular domains, and have predicted functions related to cell migration or vascular development. However, the expression patterns and known functions of other genes are not consistent with roles in these processes. This screen has identified candidates for regulation of sex specific vascular development, and has implicated a role for WNT4 signaling in the development of Sertoli and germ cell lineages not immediately obvious from previous phenotypic analyses.

Follow-up and risk of tumors in overgrowth syndromes

A striking feature of the overgrowth syndromes (OGS) is the risk of cancer. In some OGS (Beckwith-Wiedemann, Perlman, Simpson-Golabi-Behmel syndromes and hemihypertrophy) tumors appeared mostly in the abdomen (more than 94% of tumors), are usually diagnosed before 10 years, and most of them are embryonal. Conversely, in other OGS, such as Sotos syndrome, the most frequent type is lympho-hematological tumors, about two-thirds are extra-abdominal and some of these tumors may appear after the second decade of life. Based on a previous literature review, a specific schedule protocol for tumor screening was suggested for many OGS. In this article we briefly review some aspects of the current knowledge of OGS and tumors, emphasizing the follow-up of these disorders.

Risk of tumorigenesis in overgrowth syndromes: a comprehensive review

Overgrowth syndromes (OGS) comprise a heterogeneous group of disorders in which the main characteristic is that either weight, height, or head circumference is 2-3 standard deviations (SD) above the mean for sex and age. A striking feature of OGS is the risk of neoplasms. Here, the relative frequency of specific tumors in each OGS, topographic location, and age of appearance is determined by reviewing published cases. In some OGS (Perlman, Beckwith-Wiedemann, and Simpson-Golabi-Behmel syndromes and hemihyperplasia) more than 94% of tumors appeared in the abdomen usually before 10 years of age, mainly embryonal in type. In Perlman syndrome, only Wilms tumor has been recorded, whereas in Sotos syndrome, lympho-hematologic tumors are most frequent. Based on literature review, a specific schedule protocol for tumor screening is suggested for each OGS. A schedule with different intervals and specific tests is proposed for a more rational cost/benefit program for these disorders.

The sweet and sour of cancer: glycans as novel therapeutic targets

A growing body of evidence supports crucial roles for glycans at various pathophysiological steps of tumour progression. Glycans regulate tumour proliferation, invasion, haematogenous metastasis and angiogenesis, and increased understanding of these roles sets the stage for developing pharmaceutical agents that target these molecules. Such novel agents might be used alone or in combination with operative and/or chemoradiation strategies for treating cancer.

Regulatory variation at glypican-3 underlies a major growth QTL in mice

The genetic basis of variation in complex traits remains poorly understood, and few genes underlying variation have been identified. Previous work identified a quantitative trait locus (QTL) responsible for much of the response to selection on growth in mice, effecting a change in body mass of approximately 20%. By fine-mapping, we have resolved the location of this QTL to a 660-kb region containing only two genes of known function, Gpc3 and Gpc4, and two other putative genes of unknown function. There are no non-synonymous polymorphisms in any of these genes, indicating that the QTL affects gene regulation. Mice carrying the high-growth QTL allele have approximately 15% lower Gpc3 mRNA expression in kidney and liver, whereas expression differences at Gpc4 are non-significant. Expression profiles of the two other genes within the region are inconsistent with a factor responsible for a general effect on growth. Polymorphisms in the 3′ untranslated region of Gpc3 are strong candidates for the causal sequence variation. Gpc3 loss-of-function mutations in humans and mice cause overgrowth and developmental abnormalities. However, no deleterious side-effects were detected in our mice, indicating that genes involved in Mendelian diseases also contribute to complex trait variation. Furthermore, these findings show that small changes in gene expression can have substantial phenotypic effects.

The genetic basis of variation in complex traits remains poorly understood. Here, a genetic variant is discovered that leads to increased body size in mice

Costello syndrome with pancreatic islet cell hyperplasia

A 3-month-old boy with Costello syndrome (CS) developed respiratory distress and fatal arrhythmias. An autopsy showed cardiac hypertrophy, mild coarctation of the aorta, and pancreatic islet cell hyperplasia. To our knowledge, this is the first report of a pancreatic abnormality in CS. Islet cell hyperplasia has also been observed in leprechaunism, Beckwith-Wiedemann (BWS), and Simpson-Golabi-Behmel syndromes. The syndromes are thought to involve abnormal insulin or insulin-like growth factor (IGF) pathways. Clinical similarities among these disorders and CS, together with the finding of islet cell hyperplasia, suggest that they may be related.