Analysis of the NF2 gene in oligodendrogliomas and ependymomas

doi:10.1016/S0165-4608(01)00591-X

Cancer Genetics and Cytogenetics

Volume 134, Issue 1, 1 April 2002, Pages 1-5

https://doi.org/10.1016/S0165-4608(01)00591-X Get rights and content

Abstract

Allelic losses of chromosome 22 are commonly found in ependymomas and oligodendrogliomas, suggesting that at least one tumor suppressor gene on chromosome 22 must be inactivated during the multistep process of tumorigenesis in these glial tumors. The neurofibromatosis 2 gene (NF2) located at 22q12, is a candidate tumor suppressor gene potentially involved in the pathogenesis of gliomas. Because there have been only a few studies of the NF2 gene in glial tumors other than astrocytoma, we screened the entire 17 NF2 exons for mutations in a series of 47 nonastrocytic tumors, including 40 oligodendrogliomas and 7 ependymomas. Only one mutation was detected, a 59-base pair insertion in exon 3 from a spinal anaplastic ependymoma. These results concur with previous findings proposing preferential inactivation of the NF2 gene in a subgroup of ependymomas, and suggest that the NF2 gene is not the target of chromosome 22 aberrations in oligodendrogliomas.

Introduction

Recurrent loss of chromosome 22 detected by both loss of heterozygosity (LOH) and/or cytogenetic analyses is a characteristic feature of glial tumors, including ependymomas, tumors with a major oligodendroglial component, and astrocytic neoplasms, as well as glioblastoma multiforme 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19; the location of at least one tumor suppressor gene (TSG) on chromosome 22q, nonrandomly involved in the development of malignant gliomas, has thus been proposed. Available data on the precise location of these glioma-associated TSG on 22q suggest several regions as candidate sites 20, 21, 22, 23, 24, 25, and efforts to identify the target TSG are being made. The neurofibromatosis type 2 (NF2) gene maps to 22q12 and represents a candidate for a glioma suppressor gene, since NF2 patients show a high incidence of gliomas, especially ependymomas and other intracranial tumors, primarily meningiomas and vestibular schwannomas [26].

Mutation analysis of the NF2 gene has shown the almost complete absence of alterations in astrocytic tumors, as the study of approximately 200 samples only revealed sequence variations in two grade II astrocytomas 21, 22, 27, 28, 29. The first was a transition at codon 463 (GAG to AAG) of exon 13, resulting in substitution of Glu>Lys, which was also present in the constitutional DNA of the patient with no evidence of NF2 disease [21]. The second was a single nucleotide polymorphism at codon 371 of exon 4 (AAC to AAT), with no change of Asn 371 [28]. In contrast, only 21 oligodendroglial tumors have been subject to NF2 gene mutation detection 21, 22, 29, and no alterations have been found. Regarding ependymomas, approximately 100 samples (62 of them from one laboratory) have been searched for mutations in the NF2 gene 27, 29, 30, 31, 32; 12 cases carried sequence changes, all corresponding to tumors with an intramedullar spinal location and no evidence of NF2 disease. This suggests that a subgroup of ependymomas would be associated with inactivation of the NF2 gene [32].

The interest of these findings in ependymomas and the scanty data available on oligodendrogliomas prompted us to perform a mutational analysis of the entire coding region of the NF2 gene in a series of seven ependymomas and 40 oligodendrogliomas, to determine whether the NF2 gene participates in molecular development of these glioma subtypes.

Section snippets

Tissue samples and DNA preparation

Fresh tumor tissues and blood samples were obtained from 47 patients, including four with grade II ependymomas, three anaplastic grade III ependymomas (two of them were recurrent tumors with no previous therapy), 22 grade II oligodendrogliomas, 12 grade III anaplastic oligodendrogliomas, and six grade II–III mixed oligo-astrocytomas. Tumors were diagnosed according to the World Health Organization (WHO) guidelines [33], and the tumor cell content was estimated by histologic examination to be

Results

The SSCP screening of all 17 exons of the NF2 gene, including the splice sites, showed an aberrant migration pattern in exon 3 of an ependymoma, whereas no mobility shifts were detected in any oligodendroglioma or in the remaining six ependymomas. Sequence analysis of the ependymoma bearing SSCP variation revealed a 59-base pair insertion at nucleotide 349 of exon 3 (Fig. 1). This insertion in codon 117 is a duplication of nucleotides 291–349, and shifts the reading frame, creating a stop codon

Discussion

Although loss of chromosome 22 has been found to characterize all major histological subtypes of glial tumors 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, the molecular significance in each group may be distinct. On the basis of partial 22q deletions in astrocytic neoplasms, we previously proposed the region distal to marker D22S80 at 22q13 as a critical domain at which a glioma-related TSG should be located [20], thus excluding the NF2 gene region. In fact, we have

Addendum

Lamszus et al. (Int J Cancer 2001;91:803–808) reported on NF2 gene mutations in six intramedullary spinal ependymomas [43].

Acknowledgements

Support for this work was provided by grants 00/0331 and 01/0279 from FIS, Ministerio de Sanidad, Spain. M.E.A. is supported by a fellowship from the Comunidad de Madrid.

References (43)

J.A Rey et al.
Chromosomal patterns in human malignant astrocytomas
Cancer Genet Cytogenet
(1987)
J.A Rey et al.
Chromosomal composition of a series of 22 human low-grade gliomas
Cancer Genet Cytogenet
(1987)
R.B Jenkins et al.
A cytogenetic study of 53 gliomas
Cancer Genet Cytogenet
(1989)
G Thiel et al.
Karyotypes in 90 human gliomas
Cancer Genet Cytogenet
(1992)
C.A Griffin et al.
Chromosome abnormalities in low-grade central nervous system tumors
Cancer Genet Cytogenet
(1992)
E Pruchon et al.
A cytogenetic study of 19 recurrent gliomas
Cancer Genet Cytogenet
(1994)
K Yamada et al.
Chromosome studies in 70 brain tumors with special attention to sex chromosome loss and single autosomal trisomy
Cancer Genet Cytogenet
(1994)
S Weremowicz et al.
Cytogenetic evidence for a chromosome 22 tumor suppressor gene in ependymoma
Cancer Genet Cytogenet
(1992)
S.R Rogatto et al.
Chromosomes in the genesis and progression of ependymomas
Cancer Genet Cytogenet
(1993)
C Wernicke et al.
Involvement of chromosome 22 in ependymomas
Cancer Genet Cytogenet
(1995)

J.R Sawyer et al.

Chromosome aberrations in four ependymomas

Cancer Genet Cytogenet

(1994)

J.P Park et al.

Constitutional de novo t(1;22) (p22;q11.2) and ependymoma

Cancer Genet Cytogenet

(1996)

A.M Vagner-Capodano et al.

Cytogenetic study of 33 ependymomas

Cancer Genet Cytogenet

(1999)

Y Hirose et al.

Chromosomal abnormalities subdivide ependymal tumors into clinically relevant groups

Am J Pathol

(2001)

D Watkins et al.

Loss of heterozygosity on chromosome 22 in human gliomas does not inactivate the neurofibromatosis type 2 gene

Cancer Genet Cytogenet

(1996)

C Ebert et al.

Molecular genetic analysis of ependymal tumors. NF2 mutations and chromosome 22q loss occur preferentially in intramedullary spinal ependymomas

Am J Pathol

(1999)

S.H Bigner et al.

Molecular genetic aspects of oligodendrogliomas including analysis by comparative genomic hybridization

Am J Pathol

(1999)

S.H Bigner et al.

Specific chromosomal abnormalities in malignant human gliomas

Cancer Res

(1988)

D.T Ransom et al.

Cytogenetic and loss of heterozygosity studies in ependymomas, pilocytic astrocytomas, and oligodendrogliomas

Genes Chromosomes Cancer

(1992)

D.T Ransom et al.

Correlation of cytogenetic analysis and loss of heterozygosity studies in human diffuse astrocytomas and mixed oligoastrocytomas

Genes Chromosomes Cancer

(1992)

E.K Biljsma et al.

Molecular analysis of genetic changes in ependymomas

Genes Chromosomes Cancer

(1995)

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Lead articleAnalysis of the NF2 gene in oligodendrogliomas and ependymomas

Abstract

Introduction

Section snippets

Tissue samples and DNA preparation

Results

Discussion

Addendum

Acknowledgements

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Cancer Genet Cytogenet

Am J Pathol

Cancer Genet Cytogenet

Am J Pathol

Am J Pathol

Specific chromosomal abnormalities in malignant human gliomas

Cancer Res

Cytogenetic and loss of heterozygosity studies in ependymomas, pilocytic astrocytomas, and oligodendrogliomas

Genes Chromosomes Cancer

Correlation of cytogenetic analysis and loss of heterozygosity studies in human diffuse astrocytomas and mixed oligoastrocytomas

Genes Chromosomes Cancer

Molecular analysis of genetic changes in ependymomas

Genes Chromosomes Cancer

Lead article
Analysis of the NF2 gene in oligodendrogliomas and ependymomas