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A Westerveld

Publications and source records attributed to A Westerveld.

At least 37 records · Page 2Linked to original sources
PubMed1997

Assessment of chromosomal gains and losses in oral squamous cell carcinoma by comparative genomic hybridisation.

Cytogenetic studies have demonstrated that oral squamous cell carcinomas (OSCCs) are usually characterised by complex karyotypes with many marker chromosomes. We analysed the genetic changes of six OSCC cell cultures by comparative genomic hybridisation (CGH). The CGH technique provides information on chromosomal gains and losses of the whole tumour genome in a single experiment and can therefore identify regions that harbour putative tumour suppressor genes (in the case of loss of chromosomal material) or oncogenes (in the case of gain or amplification of chromosomal material). Recurrent losses were detected at chromosome arms Xp and 3p (four cases). Gains consistently occurred at chromosome arms 8q and 9q (four cases) and at 1q, 3q, 5p, 7p, and 9p (three cases). The same six tumour cultures have previously been analysed by classical karyotyping. An important discrepancy between the two techniques was the number of losses detected: 55 with karyotyping versus 26 with CGH. On the basis of the cytogenetic complexity of these tumours and on FISH experiments that confirmed the CGH results, we conclude that genetic changes, particularly losses, can be more reliably detected by CGH analysis.

Carcinoma, Squamous Cell↗
PubMed1997

The human Achaete-Scute homologue 2 (ASCL2,HASH2) maps to chromosome 11p15.5, close to IGF2 and is expressed in extravillus trophoblasts.

Here we describe the cloning of the human Achaete Scute Homologue 2 (HASH2) gene, officially designated ASCL2 (Achaete Scute complex like 2), a homologue of the Drosophila Achaete and Scute genes. In mouse, this gene is imprinted and maps to chromosome 7. We mapped the human homologue close to IGF2 and H19 at 11p15.5, the human region syntenic with mouse chromosome 7, indicating that this imprinted region is highly conserved in mouse and man. HASH2 is expressed in the extravillus trophoblasts of the developing placenta only. The lack of HASH2 expression in non-malignant hydatidiform (androgenetic) moles indicates that HASH2 is also imprinted in man.

Amino Acid Sequence↗
PubMed1997

Comparative genomic hybridization analysis of Wilms tumors.

In this study we have applied the technique of comparative genomic hybridization (CGH) to a large series of sporadic Wilms tumors, including six samples of the associated nephroblastomatosis. The data obtained were compared with the findings of molecular studies carried out on the same material. The aims of the study were (1) to characterize the range of genetic variation in sporadic Wilms tumor and nephroblastomatosis, (2) to determine whether changes could be found that have not been detected by commonly used techniques, and (3) to compare the sensitivity of CGH with that of conventional molecular analysis. The chromosomes that showed gains and losses by CGH were similar to those previously found in molecular and cytogenetic studies, however loss of 4q was a new event identified in 2 out of 46 tumors. We did not detect amplified genetic material. Comparison of the data from the nephroblastomatosis and tumor samples from the same patient showed that loss of 7p may be associated with malignant transformation, and that losses in 1p, 11p, 4q and gains in 1q and 12q can be early events; whilst loss in 9p and gain of 8, 10q and 18 are possible secondary changes in tumor development. The combined CGH and molecular techniques used demonstrated involvement of two specific 1p regions in the etiology of Wilms tumor.

Chromosome Aberrations↗
PubMed1997

Some patients with intracranial aneurysms have a reduced type III/type I collagen ratio. A case-control study.

A reduced production of type III collagen has been reported in previous studies to be associated with intracranial aneurysms. The purpose of this prospective case-control study was to assess the possible role of a reduced type III collagen production as a risk factor for having an intracranial aneurysm. The study group consisted of 41 consecutively admitted patients with intracranial aneurysms. Intracranial aneurysms were demonstrated by intraarterial digital subtraction cerebral angiography or during operation. The control group consisted of 41 healthy volunteers matched for age and sex. Fibroblasts were cultured from skin biopsies from patients and control subjects, and the type III/type I collagen ratios were determined. The type III/type I collagen ratios in the controls ranged from 5.5 to 19.8%, with a median ratio of 10%, and none had a ratio below 5.5%. The type III/type I collagen ratios in patients ranged from 1.1 to 25.1%, with a median ratio of 10.5%, and eight patients (19.5%) had a low (< 5.5%) ratio (p = 0.005, Fisher's exact test). Our findings support the hypothesis that a reduced production of type III collagen may contribute to the formation of intracranial aneurysms in some patients.

Adult↗
PubMed1997

Malignant astrocytoma-derived region of common amplification in chromosomal band 17p12 is frequently amplified in high-grade osteosarcomas.

Recently, we reported a new amplification event that involves marker D17S67 in 17p12 in three malignant astrocytomas of patients with a very short survival. The amplified region may contain an oncogene implicated in astrocytoma tumorigenesis. To determine the extent of the amplified regions, we constructed a yeast artificial chromosome contig spanning the D17S67 region and tested the amplification status of markers that map to the contig. We determined a commonly amplified region between markers D17S1311 and D17S1875 with a maximal length of 1,630 kb. By using marker 745R, from within the commonly amplified region, we screened 60 high-grade astrocytomas but could not detect additional tumors with the amplification event. This suggests that the incidence of the amplification event in high-grade astrocytoma is low (5%). It has recently been shown by comparative genomic hybridization that amplification of 17p11-p12 is a frequent event in high-grade osteosarcomas, occurring in 20-30% of cases. Since the commonly amplified region is within 17p12, we tested 745R in 20 osteosarcomas, including 6 lung metastases, and detected amplification in 9 cases (45%). Marker 745R was found to be amplified in 4 of the 6 lung metastases (66%). From this frequent involvement and the association with clinically aggressive astrocytomas we conclude that for both tumor types presence of the amplification event seems to correlate with aggressive clinical behaviour.

Astrocytoma↗
PubMed1997

Fine mapping of a region of common deletion on chromosome arm 10p in human glioma.

Allelic loss on chromosome 10 is a frequent event in high grade gliomas. Earlier studies have shown that in most cases a complete copy of chromosome 10 is lost in the tumor. To define more accurately and specifically the region of common deletion on chromosome arm 10p, we have screened a large series of gliomas for allelic losses that exclusively affect this part of the chromosome. Allelic loss profiles were determined for 127 gliomas, including 118 astrocytomas of various malignancy grades. Seventeen tumors displayed loss of part of chromosome 10. In three of these, only chromosome arm 10p sequences were lost. The interval between loci D10S559 and D10S435 in 10p15, with a length of approximately 800 kilobase pairs, was commonly deleted in the latter tumors, suggesting that this region may harbor a tumor suppressor gene important in glioma tumorigenesis. Comparison of the allelic loss profiles in the low and high grade astrocytomas revealed that astrocytoma progression is associated with increased loss of chromosome 10 sequences.

Astrocytoma↗
PubMed1996

Lack of class I HLA expression in neuroblastoma is associated with high N-myc expression and hypomethylation due to loss of the MEMO-1 locus.

Class I HLA expression is low in neuroblastoma tumours and cell lines. We have recently mapped a modifier of methylation for HLA-C (MEMO-1) to chromosomal bands 1p35-36.1, a region deleted in many neuroblastomas. Hypomethylation of HLA-C is strongly correlated with allelic loss of the MEMO-1 locus. Here, we show that loss of MEMO-1 is associated with hypomethylation of both the 5' and 3' regions of class I HLA loci. We next investigated the relationship between methylation and expression of class I HLA in 28 cell lines of neuroectodermal tumours. Cell lines with hypermethylated HLA-C and HLA-A loci have relatively high expression, while most cell lines with hypomethylated loci have no or a reduced expression. It was reported earlier that high expression of c- or N-myc can suppress class I HLA expression. Remarkably, also N-myc amplification in neuroblastomas is associated with allelic loss of 1p35-36. Therefore, we have analysed the relationships between allelic loss of the MEMO-1 locus, class I HLA methylation and expression, and N-myc amplification and expression. This study shows a tight inter-relationship between these phenomena. Our data suggest a model in which hypomethylation of class I HLA due to loss of the MEMO-1 locus and high N-myc expression could collaborate in the down-regulation of class I HLA expression.

Cell Fusion↗
PubMed1996

Mutational analysis of the human nucleotide excision repair gene ERCC1.

The human DNA repair protein ERCC1 resides in a complex together with the ERCC4, ERCC11 and XP-F correcting activities, thought to perform the 5' strand incision during nucleotide excision repair (NER). Its yeast counterpart, RAD1-RAD10, has an additional engagement in a mitotic recombination pathway, probably required for repair of DNA cross-links. Mutational analysis revealed that the poorly conserved N-terminal 91 amino acids of ERCC1 are dispensable for both repair functions, in contrast to a deletion of only four residues from the C-terminus. A database search revealed a strongly conserved motif in this C-terminus sharing sequence homology with many DNA break processing proteins, indicating that this part is primarily required for the presumed structure-specific endonuclease activity of ERCC1. Most missense mutations in the central region give rise to an unstable protein (complex). Accordingly, we found that free ERCC1 is very rapidly degraded, suggesting that protein-protein interactions provide stability. Survival experiments show that the removal of cross-links requires less ERCC1 than UV repair. This suggests that the ERCC1-dependent step in cross-link repair occurs outside the context of NER and provides an explanation for the phenotype of the human repair syndrome xeroderma pigmentosum group F.

Amino Acid Sequence↗
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↗
PubMed1996

Positional cloning of genes involved in the Beckwith-Wiedemann syndrome, hemihypertrophy, and associated childhood tumors.

The Beckwith-Wiedemann syndrome (BWS) is an overgrowth malformation syndrome that occurs with an incidence of 1:13,700 births. There is a striking incidence of childhood tumors found in BWS patients. Various lines of investigation have localized "imprinted" genes involved in BWS and associated childhood tumors to 11p15. High resolution mapping of 8 rare balanced chromosomal BWS rearrangements enabled us to identify three distinct regions on chromosome 11p15 that might harbor genes involved in the above-mentioned disorders. These results suggest genetic heterogeneity that correlates with the clinical heterogeneity seen in the patients studied. Expressed candidate gene sequences from these regions have been cloned and partly sequenced. These transcripts are either disrupted by or are at least within a few kb of these BWS chromosome breakpoints. So far, zinc-finger sequences and one Kruppel-associated box (KRAB) domain were found in independent candidate genes which are compatible with a regulating function of growth promoting genes. The abundance of expression of these genes varies from low abundant in all adult and fetal tissues tested to detectable on Northern blots of adult tissues. In addition to our 11p15 studies we have analyzed additional chromosome regions, in particular 1p. Cytogenetic, loss of heterozygosity (LOH) and comparative genomic hybridization (CGH) studies have identified 1p35 as a region of interest. A positional cloning effort to identify a balanced 1p35 translocation found in a Wilms tumor has led to the isolation of a YAC, crossing this breakpoint.

Adult↗
PubMed1996

Centromeric breakage as a major cause of cytogenetic abnormalities in oral squamous cell carcinoma.

Cytogenetic analysis of short-term explant tumor cultures derived from 11 human oral squamous cell carcinomas (nine from primary tumors and two from nude mouse xenograft cultures) revealed clonal chromosomal aberrations with multiple numerical and structural changes in all tumors. Recurrent breakpoints were located at chromosomal bands 1p13 (five tumors), 11q13 (four tumors), 3q27-29 (three tumors), and 12q13 (three tumors). Four tumors had a homogeneously staining region at band 11q13. Consistent chromosomal losses included 3p, 9p13-pter, and 18q22-qter, each occurring in eight tumors. Gain of material was observed for chromosome arms 3q, 5p, 7p, and 8q. As many as 134 of a total of 218 chromosomal breakpoints (61%) occurred in centromeric regions, often resulting in isochromosomes and unbalanced whole-arm translocations. Using fluorescence in situ hybridization with chromosome-specific centromeric alphoid repeat probes, two whole-arm translocations, der(Xq;11q) and a der(3q;11q), each from a different tumor, were shown to contain juxtaposed centromeric sequences of both participating chromosomes, strongly suggesting that the breakpoints were within the centromeres. We propose that centromeric breakage is an important mechanism for the generation of genetic imbalance in the development of oral squamous cell carcinoma.

Animals↗
PubMed1996

No mutations found by RET mutation scanning in sporadic and hereditary neuroblastoma.

Neuroblastoma occasionally occurs in diseases associated with abnormal neurocrest differentiation, e.g. Hirschsprung disease. Expression studies in developing mice suggest that the proto-oncogene RET plays a role in neurocrest differentiation. In humans expression of RET is limited to certain tumor types, including neuroblastoma, that derive from migrating neural crest cells. Mutations of RET are found associated with Hirschsprung disease. These data prompted us to investigate expression of RET and to search for gene mutations in neuroblastoma. Out of 16 neuroblastoma cell lines analyzed, 9 show clear expression of RET in a Northern blot analysis. In a single strandt conformation polymorphism (SSCP) analysis of all exons, no mutations were detected other than neutral polymorphisms. In a patient with neuroblastoma, from a family in which different neurocrestopathies, including neuroblastoma and Hirschsprung disease, had occurred, we also failed to detect RET mutations. Possibly, expression of RET in neuroblastoma merely reflects the differentiation status of the tumor cells. The absence of mutations suggests that RET does not play a crucial role in the tumorigenesis of neuroblastoma.

Drosophila Proteins↗
PubMed1996

Allelic loss of the short arm of chromosome 4 in neuroblastoma suggests a novel tumour suppressor gene locus.

Neuroblastoma is a childhood neural crest tumour, genetically characterized by frequent deletions of the short arm of chromosome 1 and amplification of N-myc. Here we report the first evidence for a neuroblastoma tumour suppressor locus on 4pter. Cytogenetically we demonstrated rearrangements of 4p in 7 out of 26 evaluable tumours (27%). Subsequent analysis of loss of heterozygosity (LOH) by Southern blotting revealed allelic loss of 4p in 16/82 (19.5%) informative neuroblastomas. Taken together cytogenetic and Southern blot analyses showed loss of 4p in 20/86 neuroblastomas analysed (23%). The common deleted region was bordered by the probe D4S123 and encompassed the distal 34 cM of 4p. We found no evidence for genomic imprinting of the 4p locus as the 4p alleles lost in the tumours were of random maternal and paternal origin. LOH4p was found at all disease stages and in every age group. Furthermore LOH4p was present both in cases with and without LOH1p and amplification of N-myc.

Alleles↗
PubMed1996

A human modifier of methylation for class I HLA genes (MEMO-1) maps to chromosomal bands 1p35-36.1.

Class I HLA genes are expressed in almost all tissues, but expression is low or undetectable in many neuroblastomas. We analysed class I HLA methylation in normal tissues and in 28 neuroectodermal tumour cell lines. HLA-C is hypermethylated in normal adult tissues and 13 cell lines, while 15 cell lines show the hypomethylated phenotype. Hypomethylation of HLA-C strongly correlates with hemizygous deletion of a 9 cM interval on 1p35-36.1, suggesting that this region encodes a modifier of methylation for HLA-C. To test whether hypomethylation of class I HLA genes results from loss of a modifier gene, we fused a hypomethylating neuroblastoma cell line with a hypermethylating cell line. Methylation of class I HLA genes was induced in the hybrids. Furthermore, methylation of HLA-C, -E and -A genes, which are encoded in a 1.4 Mb region on 6p21, is correlated in most cell lines. Our results suggest that 1p35-36.1 encodes a modifier of methylation for class I HLA genes, that is deleted in many neuroblastomas.

Alleles↗
PubMed1996

Fine mapping of the autosomal recessive retinitis pigmentosa locus (RP12) on chromosome 1q; exclusion of the phosducin gene (PDC).

In a previous study on a large pedigree from a genetically isolated population in the Netherlands, we localized a gene for autosomal recessive retinitis pigmentosa with paraarteriolar preservation of the retinal pigment epithelium (PPRPE) on the long arm of chromosome 1. In this study, we present an integrated genetic map of the target region. The resulting genetic order of the markers was used to construct haplotypes and to screen for key-recombinants in the pedigree. The obligate RP12 region was reduced from 16 cM to 5 cM between the markers D1S533 and CACNL1A3. The CACNL1A3 and phosducin (PDC) genes were placed outside the candidate gene region, thereby excluding the involvement of these genes in retinitis pigmentosa with PPRPE. Our data result in the following order of the markers and genes in the region 1q31 --> q32.1: cen-D1S158-(D1S238-D1S422)/PDC- D1S533-RP12/(F13B-D1S413)-CACNL1A3-DIS4 77-D1S306-D1S53-tel.

Base Sequence↗
PubMed1995

Multiple genetic loci within 11p15 defined by Beckwith-Wiedemann syndrome rearrangement breakpoints and subchromosomal transferable fragments.

Beckwith-Wiedemann syndrome (BWS) involves fetal overgrowth and predisposition to a wide variety of embryonal tumors of childhood. We have previously found that BWS is genetically linked to 11p15 and that this same band shows loss of heterozygosity in the types of tumors to which children with BWS are susceptible. However, 11p15 contains > 20 megabases, and therefore, the BWS and tumor suppressor genes could be distinct. To determine the precise physical relationship between these loci, we isolated yeast artificial chromosomes, and cosmid libraries from them, within the region of loss of heterozygosity in embryonal tumors. Five germ-line balanced chromosomal rearrangement breakpoint sites from BWS patients, as well as a balanced chromosomal translocation breakpoint from a rhabdoid tumor, were isolated within a 295- to 320-kb cluster defined by a complete cosmid contig crossing these breakpoints. This breakpoint cluster terminated approximately 100 kb centromeric to the imprinted gene IGF2 and 100 kb telomeric to p57KIP2, an inhibitor of cyclin-dependent kinases, and was located within subchromosomal transferable fragments that suppressed the growth of embryonal tumor cells in genetic complementation experiments. We have identified 11 transcribed sequences in this BWS/tumor suppressor coincident region, one of which corresponded to p57KIP2. However, three additional BWS breakpoints were > 4 megabases centromeric to the other five breakpoints and were excluded from the tumor suppressor region defined by subchromosomal transferable fragments. Thus, multiple genetic loci define BWS and tumor suppression on 11p15.

Base Sequence↗
PubMed1995

Assignment of the beta B1 crystallin gene (CRYBB1) to human chromosome 22 and mouse chromosome 5.

By using primers complementary to the rat beta B1 crystallin gene sequence, we amplified exons 5 and 6 of the orthologous human gene (CRYBB1). The amplified human segments displayed greater than 88% sequence homology to the corresponding rat and bovine sequences. CRYBB1 was assigned to the group 5 region in 22q11.2-q12.1 by hybridizing the exon 6 PCR product to somatic cell hybrids containing defined portions of human chromosome 22. The exon 5 and exon 6 PCR products of CRYBB1 were used to localize, by interspecific backcross mapping, the mouse gene (Crybb1) to the central portion of chromosome 5. Three other beta crystallin genes (beta B2(-1), beta B3, and beta A4) have previously been mapped to the same regions in human and mouse. We demonstrate that the beta B1 and beta A4 crystallin genes are very closely linked in the two species. These assignments complete the mapping and identification of the human and mouse homologues of the major beta crystallins genes that are expressed in the bovine lens.

Animals↗