European Human Genetics Conference 2007 June 16 – 19, 2007 ...

Cancer genetics
P0587. Differential expressed genes in favourable versus
unfavourable neuroblastoma tumors
F. E. Abel, A. Wilzen, T. Martinsson;
Biomedicine, Goteborg, Sweden.
Neuroblastoma (NB), a childhood tumor originating from neural crest
cells in the sympathetic nervous system, has a complex biological heterogeneity
depending on clinical stage and age at diagnosis. In order
to screen for genes involved in tumour development, a global micro
array expression analysis was performed on six NB tumours (three
favourable and three unfavourable). Data indicated that the expression
levels of several important players in the noradrenalin biosynthesis
pathway were significantly lower in unfavourable NB tumours
compared to favourable. The 95 most significant genes with a fold
change above 2.0 between groups were picked out for verification
with real-time PCR (with TaqMan Low Density Array cards, Applied
Biosystems) on tumours included in the micro array study. Thirteen
additional tumours were also analyzed by real-time PCR in order
to explore if the expression pattern is applicable to a larger group.
The preliminary results show that transcripts encoded by solute carrier
family 6 (SLC6A2), transcription factor AP-2 beta (TFAP2B), and
chromosome 5 open reading frame 13 (C5ORF13) all show a distinct
down-regulated pattern in unfavourable tumours versus favourable.
The protein encoded by SLC6A2 is an important mediator in the noradrenalin
biosynthesis pathway. Both TFAP2B and C5ORF13 (also
known as P311) are known to induce the expression levels of cellcycle
regulator P21. Also, TFAP2B has been shown to regulate expression
of genes required for development of tissues of ectodermal
origin, such as neural crest. These findings insist us to further explore
these genes and their involvement in neuroblastoma development
and progression.
P0588. Screening 80 unrelated neurofibromatosis type 1
patients for deletions of the NF1 gene.
O. Drozd 1,2 , O. Babenko 1,2 , M. Nemtsova 1,2 , D. Zaletayev 1,2 ;
1 Research Center for Medical Genetics, Moscow, Russian Federation, 2 I.M.
Sechenov Moscow Medical Academy, Moscow, Russian Federation.
Neurofibromatosis type I (NF1) is a common autosomal dominant
disorder affecting 1/3,500 individuals. The major diagnostic features
include café-au-lait spots, neurofibromas, axillary/inguinal freckling,
and Lisch nodules. Various constitutional mutations of the NF1 gene
have been found in NF1 patients. However, no clear genotype-phenotype
correlation has been established so far, except for patients with
deletions of the entire NF1 gene who have a more severe phenotype,
including facial abnormalities, mental retardation, developmental delay,
early development of numerous cutaneous neurofibromas, and
plexiform neurofibromas. We have developed the panel of intragenic
microsatellite markers (D17S1307, D17S1849, TAGA/TAGGint27a,
ACint27b and GTint38) for detection of NF1 region gross deletions
and indirect NF1 DNA-diagnostics. Moreover, we used 3 polymorphisms
(702A>G, 1528-29delT and 5546-19T>A) for the definition of
NF1 locus heterozygosity. A total of 80 unrelated patients who met the
diagnostic criteria for NF1 were included in our study. In five patients
all markers were homozygous and one patient had a deletion (TAGA/
TAGGint27a, GTint38). Parents DNA was accessible only for three of
five potential carriers of deletions. Among the latter, two of three had
no severe phenotype characteristic for loss of the entire NF1 gene.
Based on the heterozygosity of each marker, the probability of random
homozygosity of eight markers in one individual could be calculated
as 0.00027. It is possible to explain such contradiction by the presence
of a small number of allelic variants of marker D17S1307 and
prevalence of one allelic variant (52 %) of marker D17S1849.
P0589. Expression analysis and investigation of single
nucleotide polymorphisms in putative NF1 modifying genes
M. Wuepping, B. Bartelt-Kirbach, D. Kaufmann;
Institute of Human Genetics, Ulm, Germany.
Neurofibromatosis type 1 (NF1) is one of the most common autosomal
dominantly inherited tumor diseases. Several symptoms of NF1 as the
dermal neurofibromas show a high interfamilial variability in classical
NF1. In the familial spinal neurofibromatosis, a very rare variant of
NF1, the number and onset of neurofibromas is obviously decreased.
On the other hand, patients with microdeletions spanning the NF1 and
several contiguous genes have an earlier onset and a higher number
of dermal neurofibromas as classical NF1 patients. To explain this
variability the existence of NF1 modifying genes in this region has
been proposed. Our expression studies in dermal neurofibromas revealed
four putative NF1 modifying genes: CENTA2, UTP6, C17orf79
and RAB11FIP4. We investigated the expression level and SNP variability
of these genes in more detail. First results will be presented.
P0590. Disruptive mitochondrial DNA mutations in complex I
subunits are markers of oncocytic phenotype in thyroid tumors
G. Gasparre 1 , A. Porcelli 2 , E. Bonora 1 , L. Pennisi 1 , M. Toller 3 , L. Iommarini 4 , A.
Ghelli 2 , C. M. Betts 5 , V. Carelli 4 , M. Rugolo 2 , G. Tallini 6 , G. Romeo 1 ;
1 Unità di Genetica Medica, Policlinico Universitario S. Orsola-Malpighi, Bologna,
Italy, 2 Dipartimento di Biologia Evoluzionistica Sperimentale, University of
Bologna, Bologna, Italy, 3 Dipartimento di Patologia e Medicina Sperimentale
e Clinica (DPMSC) and Centro Interdipartimentale di Medicina Rigenerativa
(CIME), University of Udine, Udine, Italy, 4 Dipartimento di Scienze Neurologiche,
University of Bologna, Bologna, Italy, 5 Dipartimento di Patologia Sperimentale,
University of Bologna, Bologna, Italy, 6 Dipartimento di Anatomia
Patologica, Ospedale Bellaria, Bologna, Italy.
Oncocytic tumors are lesions composed of cells characterized by mitochondrial
hyperplasia particularly common in the thyroid gland. Because
of their distinctive features they represent a good model to study
the role of mitochondria in tumorigenesis. We recently demonstrated
the association between two pathogenic mitochondrial mutations and
a defective biochemical phenotype in a cell line model of oncocytoma.
To understand whether specific mitochondrial DNA (mtDNA) mutations
are associated with the oncocytic phenotype we sequenced
the entire mtDNA in 45 oncocytic thyroid tumors (HCTs), 5 oncocytic
breast tumors and 52 control cases (21 non-oncocytic thyroid tumors,
15 breast carcinomas and 16 gliomas) utilizing a recently developed
technology (Applera). Thirteen oncocytic lesions (26%) presented disruptive
mutations (nonsense or frameshift), whereas only 2 samples
presented such mutations in the non-oncocytic control group (3.8%).
In one case with multiple thyroid nodules analyzed separately a disruptive
mutation was found in the only nodule with oncocytic features.
In one of the 5 oncocytic breast tumors a disruptive mutation was
identified. All disruptive mutations were found in complex I subunit
genes and the association between these mutations and the oncocytic
phenotype was statistically significant (p=0.001). To study the
pathogenicity of these mitochondrial mutations, primary cultures from
oncocytic tumors and corresponding normal tissues were established.
Molecular and biochemical analysis and electron microscopy showed
that primary cultures derived from tumors bearing disruptive mutations
failed to maintain the mutations and the oncocytic phenotype.
We conclude that disruptive mutations in complex I subunits are markers
of thyroid oncocytic tumors.
P0591. P53, H-ras, c-myc, c-erbB2 and bcl2 analysis in oral
squamous cell carcinomas
J. Milasin 1 , B. Popovic 1 , B. Jekic 2 , G. Tredici 3 , I. Novakovic 2 , V. Lekovic 1 ;
1 School of Dentistry, Belgrade, Serbia, 2 School of Medicine, Belgrade, Serbia,
3 Department of Neurosciences, University Milano, Milano-Bicocca, Italy.
A comprehensive study of molecular changes during oral carcinogenesis
has been performed on 60 specimens of squamous cell carcinoma
(OSCCs). P53 and H-ras have been subjected to mutational
analysis by SSCP followed by sequencing. C-myc and c-erbB2 have
been tested for amplification using differential PCR and bcl2 gene expression
has been determined by immunohistochemistry.
Mutations in one or more exons of the p53 gene have been found in
60 % of cases. H-ras codons 12/13 mutations have been detected in
22% of cases, while c-myc and c-erbB2 amplification has been recorded
in 35% and 32% of specimens, respectively. Bcl2 expression
has been registered in 68% of OSCCs.
We confirmed a positive association between the presence of p53
mutations and bcl2 expression, as well as a significant correlation
between c-erbB2 amplification and bcl2 expression. No statistically
significant correlation was found between molecular and histopathological
changes (p53 mutations showed a borderline correlation with
histological grades).
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