Roberta Cinti

Tumor Origin of Endothelial Cells in Human Neuroblastoma

PURPOSE Malignant cells are genetically unstable and prone to develop chemotherapy resistance, whereas tumor vasculature is usually of host origin and genetically stable. Tumor endothelial microvessels attract interest as therapeutic targets, but their genetic instability would curtail such approach. Here, we have investigated the tumor origin of endothelial microvessels in human neuroblastoma (NB). MATERIALS AND METHODS Paraffin-embedded tissue sections from 10 MYCN-amplified tumors (six stage 4, three stage 3, and one stage 1) were studied. Endothelial cells (ECs) were detected by immunofluorescent staining for CD31 or CD105, and MYCN amplification was detected using fluorescence in situ hybridization (FISH). In xenografts of the HTLA-230 human NB cell line, human ECs were detected by CD31 staining, mouse ECs were detected by CD34 staining, and MYCN amplification and murine DNA were detected using FISH. RESULTS MYCN-amplified ECs formed approximately 70% of tumor endothelial microvessels in two stage 4 tumors and 20% in one stage 3 tumor. Similar results were obtained after EC labeling with CD31 or CD105. Staining for alpha-smooth muscle actin in combination with MYCN FISH demonstrated that tumor-derived ECs were coated with pericytes. These vessels were functional because they contained RBCs. Approximately 70% of endothelial vessels from HTLA-230 xenografts stained for human CD31, but not murine CD34, and displayed MYCN amplification, thus proving their tumor origin. CONCLUSION NB-associated endothelial microvessels can originate from tumor cells, and this finding challenges the tenet that tumor vasculature is genetically stable. The possibility that NB-derived ECs are chemotherapy resistant warrants further investigation.

Genetic Mapping to 10q23.3-q24.2, in a Large Italian Pedigree, of a New Syndrome Showing Bilateral Cataracts, Gastroesophageal Reflux, and Spastic Paraparesis with Amyotrophy

We have recently observed a large pedigree with a new rare autosomal dominant spastic paraparesis. In three subsequent generations, 13 affected individuals presented with bilateral cataracts, gastroesophageal reflux with persistent vomiting, and spastic paraparesis with amyotrophy. Bilateral cataracts occurred in all affected individuals, with the exception of one patient who presented with a chorioretinal dystrophy, whereas clinical signs of spastic paraparesis showed a variable expressivity. Using a genomewide mapping approach, we mapped the disorder to the long arm of chromosome 10 on band q23.3-q24.2, in a 12-cM chromosomal region where additional neurologic disorders have been localized. The spectrum of phenotypic manifestations in this family is reminiscent of a smaller pedigree, reported recently, confirming the possibility of a new syndrome. Finally, the anticipation of symptoms suggests that an unstable trinucleotide repeat may be responsible for the condition.

Molecular cloning and mapping of a human cDNA (PA2G4) that encodes a protein highly homologous to the mouse cell cycle protein P38-2G4

We have identified a novel human gene with strong homology to the mouse Pa2g4 cell cycle gene. This novel gene (called PA2G4) belongs to a gene family with members in several chromosome regions: 3q24-q25, 6q22, 9q21, 12q13, 18q12, 20p12 and Xq25. A composite cDNA of 1697 nucleotides was isolated. The sequence of this cDNA predicts a protein of 394 amino acids. The deduced amino acid sequence of this human protein shows very strong homology to the mouse protein p38-2G4. The cDNA analyzed probably corresponds to a functional copy found at 12q13.

Characterization of a murine gene homologous to the bovine CaCC chloride channel.

The bovine CaCC protein is a putative Ca2+-dependent Cl- channel of airway epithelial cells. Therefore, CaCC proteins could contribute to transepithelial Cl- transport and accordingly modify the phenotype of cystic fibrosis (CF) patients. We have identified a murine EST containing a full-length cDNA coding for a 902-amino-acid protein highly homologous to bovine CaCC. The murine gene (mCaCC) maps to chromosome 3 at the H2-H3 band and is expressed, as indicated by Northern blot analysis, in mouse skin and kidney but not in brain, heart, lung or testis. RT-PCR indicates a low expression in tracheal epithelial cells. Heterologous expression of mCaCC in Xenopus oocytes elicits membrane currents that are anion-selective and inhibited by DIDS and by niflumic acid, a blocker of the endogenous chloride current in oocytes. The identification of genes belonging to the CaCC family will help to evaluate their role as ion channels or channel regulators and their actual contribution to epithelial chloride transport.

Molecular characterisation of a supernumerary ring chromosome in a patient with VATER association

Editor—Supernumerary marker chromosomes are rare with an incidence of 0.3-1.5/1000 newborns. Most carriers have a normal phenotype but in 15% of non-satellited marker cases mental retardation and minor anomalies have been reported.1 The origin of several supernumerary ring marker chromosomes has been identified by fluorescence in situ hybridisation (FISH).2 The VATER association is characterised by non-random occurrence of Vertebral anomalies, Anal atresia, Tracheo-oesophageal fistula with Esophageal atresia, Radial limb dysplasia, and Renal defects.3 The acronym VACTERL is used in cases with additional Cardiac and Limb malformations.4 VACTERL with hydrocephalus is thought to be an autosomal recessive disorder distinct from the VATER association.5 Other defects that occur less frequently have been also described.6 A defect in blastogenesis was suggested as a possible aetiology of this malformation spectrum. Martinez-Frias et al 7proposed that combinations of anomalies of blastogenetic origin, such as VATER/VACTERL, should be considered and called “polytopic field defects” instead of the generic term “association”. The knowledge that maternal intake of some teratogens, such as oestroprogestins8 or methimazole,9 may be associated with VATER/VACTERL in the newborn, probably affecting blastogenesis, and familial occurrence of VASTER/VACTERL10 11 suggest heterogeneity in the pathogenesis of the association, although it appears that the underlying causative event takes place at a very early stage of embryonic development. Only one chromosome abnormality has been described in VATER association, a patient with an interstitial 6q deletion,12while an additional case of VATER with 9qh+ has been reported.13 We report here an additional patient with malformations characteristic of VATER association and mosaicism for a small supernumerary ring chromosome derived from the pericentromeric region of chromosome 12. The proband was the term product of an uneventful pregnancy, requiring elective caesarean section because of uterine inertia. Birth weight …

The phenotype of a 45,X male with a Y/18 translocation

In this report, we describe a male infant with a 45, X karyotype; the entire short arm and the centromere of the Y chromosome were translocated onto the short arm of chromosome 18, resulting in an unbalanced dicentric chromosome. Breakpoints were identified by in situ fluorescence hybridization (FISH) on the proximal Yq11 and 18p11.2. Both Y and 18 centromeric alphoid sequences were identified on the derived 18 chromosome. Clinical features were compatible with 18p‐ syndrome and no Turner stigmata were present in our propositus. Short stature was likely to be related to the deletion of 18p and/or Yq, where a gene involved in stature determination has been located proximal to a gene involved in spermatogenesis (AZF).

HOX11L1, a gene involved in peripheral nervous system development, maps to human chromosome 2p13.1 →p12 and mouse chromosome 6C3-D1

HOX11L1 is a homeobox gene involved in peripheral nervous system development as confirmed by knockout mice exhibiting megacolon with enteric ganglia, a phenotype associated in human with Intestinal Neuronal Dysplasia (IND). Using FISH and radiation hybrids we have localized HOX11L1 to human chromosome 2p13.1→p12, in a 14-cR interval between WI-5987 (D2S2088) and GCT1B4 (D2S2497), and confirmed the synteny between mouse 6C3–D1 and human 2p13.1→p12 chromosomes by mapping an EST cDNA clone corresponding to mouse HOX11L1 (Tlx2).

High-resolution mapping of the X-linked lymphoproliferative syndrome region by FISH on combed DNA

X-linked lymphoproliferative syndrome is an inherited immunodeficiency for which the responsible gene is currently unknown. Several megabase-sized deleted regions mapping to Xq25 have been identified in XLP patients, and more recently a 130-kb deletion has been reported (Lamartine et al., 1996; Lanyi et al., 1996). To establish a physical map of this deleted region and to identify the XLP gene, two cosmid contigs were established (Lamartine et al., 1996). However, the physical map of this region is still uncompleted and controversial and three points remain unsolved: (1) the centromeric-telomeric orientation of the whole region, (2) the relative orientation of the two contigs, and (3) the size of the gap between the two contigs. To provide a definitive answer to these questions, high-resolution mapping by fluorescence in situ hybridization on combed DNA and molecular approaches were combined to establish the physical map of the XLP region over 600 kb. Our results identified a gap of 150 kb between the two contigs, established the relative orientation of one contig to the other, and determine the centromeric-telomeric orientation of the whole region. Our results show that the order of the marker over this region is: cen...1D10T7–DF83–DXS982...tel.

Chromosomal imbalances in pediatric Burkitt-like lymphoma and review of the literature in relation to other germinal center derived B-cell tumors

This study reports on the cytogenetic features of a novel case of pediatric Burkitt-like lymphoma (BLL), that adds to the three published. Four groups of cytogenetic abnormalities were detected in the present case: (1) imbalances shared by most germinal center (GC) derived B-cell tumors including BLL (+1q, −6q, −8p, +8q24 and +11); (2) imbalances already reported in adult but not in pediatric BLL cases and shared with most GC B-cell tumors (+7, −9p, −9q, +12q, −13q, +17, +19, −3 and −4); (3) imbalances already reported in pediatric but not in adult BLL cases and shared with some GC B-cell tumors (−2q); and (4) imbalances never described before in pediatric or adult BLL, but present in different GC B-cell tumors (−6p, −1p and −18q). In view of the paucity of pediatric BLL cases published, this report adds novel, relevant information on the molecular cytogenetic features of this rare tumor.

Assignment of mouse Gfra1, the homologue of a new human HSCR candidate gene, to the telomeric region of mouse Chromosome 19

Glial cell line-derived neurotrophic factor (Gdnf) and its alpha receptor (Gfra1) interact with the Ret receptor triggering its tyrosine kinase activity. As Gdnf and Ret have been linked to the development of Hirschsprung disease (HSCR), it seems likely that Gfra1 could also be a susceptibility gene for HSCR. A further HSCR candidate gene is represented by the human homologue of the Dom (Dominant megacolon) mouse mutation, mapped to Chr 15, for which the gene has not yet been identified. In order to test if Gfra1 could be the Dom gene or if it represents a new possible HSCR locus we have undertaken the mapping of the mouse Gfra1. Using specific PCR primers on a somatic cell hybrid mapping panel and fluorescence in situ hybridization with an expressed sequence tag (EST) cDNA clone corresponding to the mouse Gfra1, we mapped the gene to mouse chromosome 19D2-D3, a region with known homology with human chromosome 10q24-->q26.