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A Westerveld

Publications and source records attributed to A Westerveld.

At least 19 recordsLinked to original sources
PubMed1996

Allelic loss of chromosome 1p as a predictor of unfavorable outcome in patients with neuroblastoma.

BACKGROUND: Neuroblastoma is a childhood tumor derived from cells of the neural crest, with a widely variable outcome. Differences in the behavior and prognosis of the tumor suggest that neuroblastoma can be divided into several biologic subgroups. We evaluated the most frequent genetic abnormalities in neuroblastoma to determine their prognostic value. METHODS: We used Southern blot analysis to study the allelic loss of chromosomes 1p, 4p, 11q, and 14q, the duplication of chromosome 17q, and the amplification of the N-myc oncogene in 89 neuroblastomas. We also determined the nuclear DNA content of the tumor cells. RESULTS: Allelic loss of chromosome 1p, N-myc amplification, and extra copies of chromosome 17q were significantly associated with unfavorable outcome. In a multivariate analysis, loss of chromosome 1p was the most powerful prognostic factor. It provided strong prognostic information when it was included in multivariate models containing the prognostic factors of age and stage or serum ferritin level and stage. Among the patients with stage I, II, or IVS disease, the mean (+/- SD) three-year event-free survival was 100 percent in those without allelic loss of chromosome 1p and 34 +/- 15 percent in those with such loss; the rates of three-year event-free survival among the patients with stage III and stage IV disease were 53 +/- 10 percent and 0 percent, respectively. CONCLUSIONS: The loss of chromosome 1p is a strong prognostic factor in patients with neuroblastoma, independently of age and stage. It reliably identifies patients at high risk in stages I, II, and IVS, which are otherwise clinically favorable. More intensive therapy may be considered in these patients. Patients in stages III and IV with allelic loss of chromosome 1p have a very poor outlook, whereas those without such loss are at moderate risk.

Blotting, Southern↗
PubMed1995

Deletion mapping in neuroblastoma cell lines suggests two distinct tumor suppressor genes in the 1p35-36 region, only one of which is associated with N-myc amplification.

Neuroblastoma is characterized by deletions of the short arm of chromosome 1 (1p) and amplification of the N-myc oncogene. We have made somatic cell hybrids of two human neuroblastoma cell lines, one with and one without N-myc expression and amplification. The expression of the amplified N-myc gene is completely switched off in the hybrids. This suggests that N-myc expression results from loss of a repressor function. As N-myc amplification is associated with loss of heterozygosity (LOH) of 1p36, we analysed 1p deletions in 16 neuroblastoma cell lines. The seven cell lines without N-myc amplification have no deletions or relatively small deletions, with an SRO on 1p36.23-33. This suggests that a tumor suppressor gene maps in this region. All nine cell lines with N-myc amplification have larger deletions, with an SRO from 1p35-36.1 to the telomere. This suggests that a second tumor suppressor gene which is associated with N-myc amplification maps more proximally. Fine mapping of 1p36 deletions in the two cell lines of the fusion experiment suggests that the distal locus is not a repressor of N-myc expression, but the more proximal locus could be a candidate for this function.

Blotting, Northern↗
PubMed1995

Molecular analysis of genetic changes in ependymomas.

Ependymomas are glial cell-derived tumors. They are, in contrast to other gliomas (astrocytomas, oligodendrogliomas, and oligoastrocytomas), ill-defined with respect to the genes and chromosomal segments important in their tumorigenesis. In this study, we extensively screened 17 ependymomas for genetic changes characteristic of other gliomas. Allelic loss was detected on chromosome arm 22q in three tumors; on chromosome 10 in two tumors; on chromosome arm 17p in two tumors; and on chromosome arms 6q, 9p, 13q, and 19q, each in one tumor. No allelic losses were found on chromosome arms 1p and 16q. None of the tumors had EGFR gene amplification. In each case, the chromosomal segment affected by the deletion included the region known to harbor a tumor suppressor gene important in glioma tumorigenesis. We conclude that ependymomas resemble the other glial neoplasms with respect to type and location of the chromosomal changes involved. Given the relatively infrequent occurrence of these genetic changes, ependymomas should be considered genetically as low-grade gliomas.

Adolescent↗
PubMed1995

Balanced translocation in a neuroblastoma patient disrupts a cluster of small nuclear RNA U1 and tRNA genes in chromosomal band 1p36.

Chromosomal band 1p36 probably harbours several neuroblastoma suppressor genes. A neuroblastoma patient has been described with a constitutional balanced translocation, t(1;17)(p36;q12-21). Cytogenetically, no loss of chromosomal material was visible. The 1p36 translocation breakpoint could therefore have inactivated one allele of a tumour suppressor gene, thus predisposing the patient to develop neuroblastoma. We localized this breakpoint by pulsed field gel electrophoresis, analysis of yeast artificial chromosomes, and fluorescence in situ hybridization. Here we report that the breakpoint is within a large cluster of small nuclear RNA U1 (RNU1) and some tRNA genes (TRE, TRN) on chromosomal band 1p36. The size of this cluster is over two megabases and it contains many other locally repeated sequences. Polyadenylated transcripts were identified for some of these sequences. In addition, the cluster is the target for integration of an adenovirus 5/SV40 hybrid virus. The translocation breakpoint maps distal of this viral integration site and proximal of marker PND.

Animals↗
PubMed1995

Maintenance of vascular endothelial cell-specific properties after immortalization with an amphotrophic replication-deficient retrovirus containing human papilloma virus 16 E6/E7 DNA.

Primary human vascular endothelial cells were immortalized by the integration of a single DNA copy of an amphotrophic, replication-deficient retrovirus containing the E6/E7 genes of human papilloma virus. To date, the resulting cell lines, designated EC-RF7 and EC-RF24, have been cultured for more than 1 year. The cell lines have retained a diploid karyotype, display no abnormalities, and are able to grow in a polar mode. Analysis of the EC-RF cell lines by indirect immunofluorescence, using an extensive panel of monoclonal antibodies, showed expression of endothelial cell-specific soluble (von Willebrand factor) and surface-bound antigens (endoglin, PCAM-1) indistinguishable from that of primary cells. In addition, the expression of the markers CD9, 13, 14, 29, 36, 40, 51, and 55 that are not restricted to endothelial cells was also similar for the immortalized and the primary endothelial cells. Immortalization did not alter the expression of the surface adhesion molecules E-selectin, VCAM-1, and ICAM-1 nor transmigration of neutrophils. The regulation of extracellular proteolytic activity by EC-RF24 was established by measuring both the induction of functional tissue factor (promotion of Factor Xa generation) and the functional deposition of plasminogen activator inhibitor 1 in the subendothelial matrix (SDS-resistant complex formation with thrombin). Finally, the biosynthesis of the endothelial cell-specific von Willebrand factor was studied in detail in the EC-RF24 cell line and the results were compared with those of primary endothelial cells.

Antigens, CD↗
PubMed1995

Family with neurofibromatosis type 2 and autosomal dominant hearing loss: identification of carriers of the mutated NF2 gene.

A family is presented in which neurofibromatosis type 2 (NF2) and autosomal dominant hearing loss segregate in an apparently independent way. The presence of the latter condition caused anxiety in all family members at risk for NF2 in whom hearing loss became apparent. Previously, we identified a G-->A transition in the donor splice site of exon 5 of the NF2 gene in a family member with proven NF2. As expected, the mutation was present in two other family members who fulfilled the diagnostic criteria for NF2. Four out of five family members at risk for NF2 developed hearing loss. Two of these had the G-->A transition. The mutation was absent in the two other individuals with hearing loss and in the fifth family member without hearing loss or other clinical symptoms. In this family, the identification of the underlying NF2 gene mutation excluded NF2 as the cause of hearing loss in two potential carriers of the mutated gene. On the other hand, it enabled the identification of two carriers of the NF2 gene mutation who did not fulfill the diagnostic criteria for NF2. They will have to be monitored very carefully for the development of NF2-associated tumors. The consistent association within this family of a relatively mild clinical phenotype with the NF2 mutation, supports earlier suggestions that intrafamilial variability is small in NF2.

Adult↗
PubMed1995

Evidence for two tumour suppressor loci on chromosomal bands 1p35-36 involved in neuroblastoma: one probably imprinted, another associated with N-myc amplification.

Previous reports on possible genomic imprinting of the neuroblastoma tumour suppressor gene on chromosome 1p36 have been conflicting. Here we report on the parental origin of 1p36 alleles lost in 47 neuroblastomas and on a detailed Southern blot analysis of the extent of the 1p deletions in 38 cases. The results are remarkably different for tumours with and without N-myc amplification. In the N-myc single copy tumours we show that the lost 1p36 alleles are of preferential maternal origin (16 of 17 cases) and that the commonly deleted region maps to 1p36.2-3. In contrast, all N-myc amplified neuroblastomas have larger 1p deletions, extending from the telomere to at least 1p35-36.1. These deletions are of random parental origin (18 of 30 maternal LOH). This strongly suggests that different suppressor genes on 1p are inactivated in these two types of neuroblastoma. Deletion of a more proximal suppressor gene is associated with N-myc amplification, while a distal, probably imprinted, suppressor can be deleted in N-myc single copy cases.

Chromosome Deletion↗
PubMed1995

Physical mapping of 3 candidate tumor suppressor genes relative to Beckwith-Wiedemann syndrome associated chromosomal breakpoints at 11p15.3.

A physical map encompassing the 3 Mb region containing the breakpoints of two Beckwith-Wiedemann Syndrome patients at chromosome band 11p15.3 is presented. The candidate tumor suppressor genes WEE1, ST5, and rhombotin, are positioned on this map relative to these Beckwith-Wiedemann syndrome translocation and inversion breakpoints.

Beckwith-Wiedemann Syndrome↗
PubMed1994

Amplification of the anonymous marker D17S67 in malignant astrocytomas.

Loss of heterozygosity (LOH) for chromosome arms 9p, 10p, 10q, and 17p and amplification of the epidermal growth factor receptor (EGFR) gene have been identified as frequent genetic changes in malignant astrocytomas. We have found amplification of the anonymous marker D17S67 on chromosome arm 17p in 10% (3 of 30 cases) of astrocytomas of the highest malignancy grade. The tumors with D17S67 amplification displayed other genetic changes on chromosome 17, including additional amplifications and deletions. All three patients with D17S67 amplification developed severe brain edema and died within 1 month after operation.

Aged↗
PubMed1994

Analysis of mutations in the SCH gene in schwannomas.

Schwannomas are benign tumors of cranial, spinal, and other nerve sheaths that develop sporadically or are inherited as part of neurofibromatosis type 2 (NF2). The NF2 gene (SCH) on chromosome 22 has recently been identified and shown to be inactivated by mutation and allele loss in some schwannomas. However, only limited regions in the SCH coding region were examined for mutations. We have extended these studies by screening virtually all coding sequences of the SCH gene (95% coverage) and adjacent splice site sequences for the presence of mutations in 48 schwannomas. All tumors (34 vestibular schwannomas and 14 schwannomas of other locations) were additionally characterized for allele loss on chromosome 22. By PCR-DGGE screening of the 16 known exons of the SCH gene, 22 mutations were found. Most of these give rise to a premature stop codon and are expected to result in the synthesis of a truncated gene product (schwannomin). Although there was no apparent hotspot for mutations, 16 of the 22 mutations occurred in the first eight exons or adjacent splice site sequences of the SCH gene. In several vestibular as well as other schwannomas loss of one SCH allele and mutational inactivation of the second allele were identified in the same tumor. Our data indicate that the SCH gene is implicated in the development of schwannomas of all locations in the nervous system.

Alleles↗
PubMed1994

Assignment of a gene for autosomal recessive retinitis pigmentosa (RP12) to chromosome 1q31-q32.1 in an inbred and genetically heterogeneous disease population.

Linkage analysis was carried out in a large family segregating for autosomal recessive retinitis pigmentosa (arRP), originating from a genetically isolated population in The Netherlands. Within the family, clinical heterogeneity was observed, with a major section of the family segregating arRP with characteristic para-arteriolar preservation of the retinal pigment epithelium (PPRPE). In the remainder of the ar-RP-patients no PPRPE was found. Initially, all branches of the family were analyzed jointly, and linkage was found between the marker F13B, located on 1q31-q32.1, and RP12 (zmax = 4.99 at 8% recombination). Analysis of linkage heterogeneity between five branches of the family yielded significant evidence for nonallelic genetic heterogeneity within this family, coinciding with the observed clinical differences. Multipoint analysis, carried out in the branches that showed linkage, favored the locus order 1cen-D1S158-(F13B, RP12)-D1S53-1qter (zmax = 9.17). The finding of a single founder allele associated with the disease phenotype supports this localization. This study reveals that even in a large family, apparently segregating for a single disease entity, genetic heterogeneity can be detected and resolved successfully.

Adult↗
PubMed1994

Allele loss on chromosomes 10 and 17p and epidermal growth factor receptor gene amplification in human malignant astrocytoma related to prognosis.

Patients with high-grade astrocytomas have a poor prognosis. However, considerable variation exists within this group of patients with respect to post-operative survival. In order to determine whether genetic alterations might be of help in subdividing this group, we used allele loss on chromosomes 10 and 17p and epidermal growth factor receptor (EGFR) gene amplification in the tumours as genetic parameters and determined their prognostic value. A series of 47 malignant (grade III and grade IV) tumours were genetically characterised, and four types of tumours were found. Type 1 tumours had loss of heterozygosity on chromosome arm 17p (LOH 17p) as the sole genetic alteration. Patients with this type of tumour were relatively young (mean age 39 years) and had a median survival period of 17 months. Type 2 tumours displayed only allele loss on chromosome 10 (LOH 10), type 3 tumours had LOH 10 + LOH 17p and type 4 tumours contained LOH 10 + EGFR gene amplification. Patients with types 2, 3 and 4 tumours were older (mean ages 59, 65 and 54 years respectively) and had a shorter survival (median duration 6, 3 and 2 months respectively) than type 1 patients. Multivariate analysis indicated that the genetic subdivision was a significant prognostic variable. In this study, age proved to be of minor importance with regard to survival. Our study revealed a predominance of frontally located tumours in patients with type 1 tumours, i.e. with LOH 17p only.

Adult↗
PubMed1994

A multimegabase cluster of snRNA and tRNA genes on chromosome 1p36 harbours an adenovirus/SV40 hybrid virus integration site.

Adenovirus type 12 (Ad12) induces gaps at chromosomal bands 1p36, 1q21, 1q42-43 and 17q21 after infection of human embryonic kidney cells. Three of these bands harbour small nuclear RNA genes or pseudogenes, but the study of a possible relationship has been hampered by the lytic character of adenovirus infection. A non-lytic Ad5/SV40 hybrid virus preferentially integrates at 1p36 and the integration site has been cloned. Chromosomal band 1p36 encodes genes for small nuclear RNA U1 (RNU-1) and for the tRNAs of glutamic acid (TRE) and asparagine (TRN). Each of these genes is encoded by 15-30 copies. We studied the organization of these genes and of the viral integration site by pulsed field gel electrophoresis (PFGE) and analysis of yeast artificial chromosomes (YACs). We show that RNU-1, TRE and TRN genes are scattered over a region of probably more than 2 Mb with intergenic distances of up to 125 kb. The Ad5/SV40 integration site maps to identical chromosomal NotI fragments as RNU-1 and TRE. Fine mapping of a YAC shows that the integration site is within 40-70 kb of genes for RNU-1, TRN and TRE.

Adenoviruses, Human↗
PubMed1994

Recurrent 1;17 translocations in human neuroblastoma reveal nonhomologous mitotic recombination during the S/G2 phase as a novel mechanism for loss of heterozygosity.

Neuroblastomas often show loss of heterozygosity of the chromosomal region 1p36 (LOH 1p), probably reflecting loss of a tumor-suppressor gene. Here we describe three neuroblastoma tumors and two cell lines in which LOH 1p results from an unbalanced translocation between the p arm of chromosome 1 and the q arm of chromosome 17. Southern blot and cytogenetic analyses show that in all cases the chromosome 17 homologue from which the 1;17 translocation was derived is still present and intact. This suggests a model in which a translocation between the short arm of chromosome 1 and the long arm of chromosome 17 takes place in the S/G2 phase of the cell cycle and results in LOH 1p. Nonhomologous mitotic recombination in the S/G2 phase is a novel mechanism of LOH.

Alleles↗
PubMed1993

Regional fine mapping of the beta crystallin genes on chromosome 22 excludes these genes as physically linked markers for neurofibromatosis type 2.

Neurofibromatosis type 2 (NF2) is a rare autosomal dominant disease, characterized by the development of bilateral vestibular schwannomas. The NF2 gene has been assigned to chromosome 22. Cataract and other eye abnormalities are frequently seen in NF2 patients. The specific association of eye abnormalities and NF2 might be caused by a genetic change on chromosome 22 that affects both the NF2 gene and a physically linked crystallin gene. In order to test this hypothesis, we regionally localized the known crystallin genes (i.e. CRYBB2, CRYBB2P1, CRYBB3, and CRYBA4) on chromosome 22. Crystallin gene-specific probes were hybridized to an extended panel of human x rodent somatic cell hybrids containing various portions of chromosome 22. It was found that all crystallin genes map to a very small region on chromosome 22 that is physically separate from the NF2 gene region by at least 160 kb of DNA. In addition, we found that the beta B crystallin genes (CRYBB2, CRYBB2P1, and CRYBB3) are clustered on a 300 kb SacII fragment and that the beta A4 crystallin gene (CRYBA4) is not part of this cluster. We conclude that the ocular manifestations in many NF2 patients are probably not the primary consequence of rearrangements on chromosome 22 that involve both the NF2 gene and a nearby beta crystallin gene.

Animals↗
PubMed1993

High-resolution chromosomal localization of the human calcitonin/CGRP/IAPP gene family members.

We report the high-resolution localization of the human calcitonin/CGRP genes, CALCA, CALCB, and the pseudogene CALCP, to a 220-kb SacII fragment on chromosome 11p15.2-p15.1, using prometaphase fluorescence in situ hybridization (FISH), two-color interphase FISH, and pulsed-field gel electrophoresis analysis. The related islet amyloid polypeptide (IAPP) gene was assigned to human chromosome 12p12.3-p12.1. The results support an evolutionary relationship between the calcitonin/CGRP genes and the IAPP gene and between parts of human chromosomes 11 and 12.

Amyloid↗
PubMed1993

In situ glucose-6-phosphate dehydrogenase activity during development of pre-implantation mouse embryos.

Glucose-6-phosphate dehydrogenase activity was analysed cytophotometrically in oocytes and pre-implantation embryos of mice. A bimodal distribution pattern was not found. Therefore, female and male embryos could not be discriminated on the basis of linkage of the enzyme with the X-chromosome during the pre-implantation period. The dehydrogenase activity in ovulated eggs and pre-implantation embryos up to the 8-cell stage was 65% of that present in follicular oocytes. In morulae and blastulae, the activity was further decreased to a level that was only 10-20% of the activity present in oocytes. The dramatic decrease in dehydrogenase activity could not be explained by modulation of the enzyme molecules, because KM values did not vary strongly. It is unlikely that the abundant activity of glucose-6-phosphate dehydrogenase in oocytes is due to high activity of the pentose phosphate pathway because of the low activity of 6-phosphogluconate dehydrogenase, the next step in this pathway. It is concluded that high activity of glucose-6-phosphate dehydrogenase in oocytes is needed for keeping oocytes viable, and for generation of NADPH which is important for the fertilization process.

Animals↗