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

Cancer genetics
cinoma (ESCC), which it is predominant cancer in esophagus, is very
high in northern Iran. The incidence pattern of esophageal cancer is
different among Iranian population and up to 171/100,000. So, identification
of p53 gene mutations and polymorphisms is very important
to find the major causes of this type of cancer in Iran. Several studies
were described the polymorphism in intron 3 of the p53 gene (16bp
intron 3 insertions) and susceptibility to several types of cancer and
diseases. This type of polymorphism can change the expression of
p53 gene.
In this investigation, we assessed allele frequency of p53 polymorphism
in intron 3 among Iranian ESCC patients and healthy controls.
The p53 genotypes were determined by direct DNA sequencing analysis
in healthy controls and patients. Among the ESCC patients subjects,
the 16bp intron 3 polymorphism for p53 gene were significantly
higher than healthy controls. Our finding suggested that p53 genotype
may play an important role in developing esophageal tumor among
ESCC patients. It is suggested that protein expression of the p53 gene
can be investigate among Iranian ESCC patients in the future.
P0597. Epigenetic regulation of shc1 protein expression, and
genetic variation within the SHC1 gene in breast carcinomas.
K. Duda, L. Hansen;
University of Aarhus, Aarhus, Denmark.
The SHC1 gene encodes three isoforms: p66shc, p52shc and p46shc.
Both p52/46shc activate the mitogen activated protein kinase pathway
(MAPK), in contrary to p66shc which downregulates MAPK. Moreover
p66shc plays an important role in apoptosis and response to oxidative
stress by transferring signal from p53. Despite that p66shc and p52/
46shc are involved in different cell functions, they all play an important
role in tumorigenesis.
Western blot analysis of cytosol fractions from breast tumours revealed
that p66shc protein expression is decreased for most of the samples.
Sequencing of bisulphite treated DNA from the same patients showed
that the level of methylation inside the p66shc promoter region correlates
with protein expression. Additionally, samples which did not fit
properly to this thesis underwent mutation analysis. Exon 1 and the
promoter region of SHC1 were sequenced in 20 breast tumours, but
no common mutation was found. There was discovered mutation within
the Sp1 binding site for one of the samples, but a single nucleotide
change did not affect expression of p66shc. Moreover, SNP analysis
was performed, comprising four known and two new polymorphisms
within the common part for all 3 SHC1 isoforms. 200 DNA breast cancer
samples and 252 DNA samples from healthy individuals serving as
controls were analyzed. Two independent haplotypes were identified
based on the SNP genotypes. Despite the presence of two rare polymorphisms,
one of the discovered haplotypes may have a protective
effect against breast cancer. The genotype was twice as frequent in
the control population as in the tumour samples.
P0598. p73 regulates PTEN genic expression
C. Puppin 1 , F. Frasca 2 , V. Vella 2 , L. Messina 2 , R. Vigneri 2 , G. Damante 1 ;
1 Dipartimento di Scienze e Tecnologie Biomediche, Università di Udine, Udine,
Italy, 2 Endocrinologia, Dipartimento di Medicina Interna e di Medicina Specialistica,
Università di Catania, Catania, Italy.
p73 belongs to a family of p53-related nuclear transcription factors that
includes p53, p73 and p63. Differentially from p53, p73 is expressed
as two NH2-terminally distinct isoforms, due to a second downstream
promoter: transcriptionally active (TAp73) and transcriptionally inactive
(ΔNp73) forms. The ΔNp73 isoforms can act as dominant negative
inhibitors of the TA isoforms and p53, so TA and ΔN show pro- and antiapoptotic
properties, respectively. Moreover additional complessity is
generated at the COOH terminus because p73 undergoes multiple
COOH-terminal splicing (α being full-length isoforms). PTEN is a dualspecificity
phosphatase and has a tumor suppressor function. This
study investigates the regulation of PTEN expression by p73 in thyroid
cells because in thyroid carcinomas both decrease of PTEN expression
and increase of p73 expression have been previously shown. Stable
thyroid cell line was generated expressing inducible p73 isoforms,
these cells showed incremented PTEN protein upon over expression
of TAp73α and β; instead cell line expressing ΔNp73α showed decremented
PTEN protein. Cell transfection studies indicated that TAp73α
and TAp73β can activate PTEN promoter, instead ΔNp73α inhibits it,
in a p53 independent way. Moreover the ΔNp73α inhibitory action is
prevalent on TAp73α and TAp73β activatory actions. This evidence
supposes that in thyroid cancers, in which there are a high ΔNp73α
expression respect to the normal thyroid tissue, ΔNp73α could reduce
PTEN expression even in presence of the others activating isoforms.
P0599. Searching for polymorphisms in paclitaxel elimination
pathway influencing drug efficacy and toxicity
S. Leskelä1 , C. Jara2 , J. García-Donás2 , R. Villafañe2 , J. Sánchez-Torres2 ,
C. Montero-Conde1 , I. Landa1 , E. López-Jiménez1 , R. Letón1 , A. Cascón1 , M.
Robledo1 , C. Rodríguez-Antona1 ;
1 2 Spanish National Cancer Research Centre, Madrid, Spain, Unidad de Oncología
Médica, Fundación Hospital Alcorcón, Madrid, Spain.
Paclitaxel is an anti-cancer drug widely used in the treatment of a
variety of solid tumors, including breast, ovarian and lung. There is
a large interindividual variation in the efficacy and adverse effects of
this drug, mainly hematologic toxicity and neurotoxicity. It has been
proposed that polymorphisms in genes encoding drug-metabolizing
enzymes and drug transporters might contribute to the differences
in paclitaxel outcome. Thus, the aim of this work is to identify SNPs
involved in paclitaxel elimination that could influence its efficacy and
toxicity. Paclitaxel elimination is mediated by hepatic metabolism and
biliar excretion: the uptake of paclitaxel into the hepatocytes is mediated
by the organic anion transporting polypeptide (OATP)1B3, in
the liver cytochrome P450 2C8 (CYP2C8) and CYP3A4/5 hydroxylate
paclitaxel and the P-glycoprotein mediates biliar excretion. Thus, we
selected variants in these genes and genotyped them in more than
80 oncology patients treated with paclitaxel: four CYP2C8 SNPs from
which two are in the coding region; one CYP3A5 SNP causing alternative
splicing; one CYP3A4 promoter SNP influencing transcription; two
coding OATP1B3 SNPs and three MDR1 SNPs previously associated
with altered activity. Neurotoxicity was evaluated in the patients and
the influence of clinical variables, such as total paclitaxel dose, time
to neurotoxicity and time to recovery were taken into account in the
study. Then, the genotypes were compared to the clinical data of the
patients, in order to assess their effect. In conclusion, the identification
of genetic variants involved in paclitaxel elimination could be useful to
predict drug effects.
P0600. Molecular genetic analysis of pheochromocytomas and
paraganglioma in Czech patients
Z. Musil 1 , A. Krepelova 1 , J. Widimsky 2 , T. Zelinka 2 , M. Kohoutova 1 ;
1 Institute of Biology and Medical Genetics of the First Faculty of Medicine,
Prague, Czech Republic, 2 Third Medical Department - Clinical Department of
Endocrinology and Metabolism of the First Faculty of Medicine, Prague, Czech
Republic.
The pheochromocytoma is tumor arising in adrenal or extra-adrenal
sites and occurs as a sporadic form or, less frequently, in familial setting
as a part of inherited syndromes. Paraganglioma of the head and
neck occurs mostly sporadically and also in syndromic or nonsyndromic
familial settings. To date four susceptibility genes for pheochromocytoma
have been reported that included RET proto-oncogene, VHL tumor
suppressor gene and recently identified genes SDHB and SDHD
for succinate dehydrogenase subunit B and D respectively. Mutations
in these genes can predispose one to pheochromocytoma and paraganglioma.
All established genes were analyzed to investigate possible genetic
cause of pheochromocytoma and paraganglioma in the population of
Czech patients. Among 100 patients we have found several previously
described mutations or polymorphisms. Besides that one novel mutation
was found in the SDHB gene in a child patient. We conclude that a
large part of diseases could be be due to mutations in an unidentified
gene(s).
Supported by the grant project MŠMT ČR MSM0021620808
P0601. Methylation-associated PHOX2B gene silencing in human
neuroblastoma
L. de Pontual1 , D. Trochet1 , F. Bourdeaut2 , S. Thomas1 , H. Etchevers1 , A.
Chrompret3 , D. Valteau3 , L. Brugière3 , A. Munnich1 , O. Delattre2 , S. Lyonnet1 , I.
Janouex-Lerosey2 , J. Amiel1 ;
1 2 3 Département de Génétique, Paris, France, Institut Curie, Paris, France, Institut
Gustave Roussy, Paris, France.
Neuroblastoma (NB), an embryonic tumour originating from neural
crest cells, is one of the most common solid tumours in childhood.
1