2008 Barcelona - European Society of Human Genetics

Cancer genetics
MGMT has been associated with a better response to TMZ-chemotherapy
. We were also able to show that TMZ increases the median
survival time of patients with tumors harbouring deletions on 9p within
the region for p15 and p16 .
The aim of our current study was to investigate the methylation status
of p15, p16, 14 ARF and MGMT and correlate these results with the clinical
data .
DNA was isolated from fresh frozen GBM biopsies (n=27) and modified
by sodium bisulfite. Promotor methylation of p15, p16, p14 ARF
and MGMT was analyzed by MS-PCR . Only patients with a KPS >70,
radiation and TMZ-chemotherapy after radical tumor resection were
included .
We observed promotor hypermethylation of MGMT in 56%, and of
p15 in 37% of the tumors, whereas hypermethylation of p16 and p14 arf
were rare .
Interestingly, hypermethylation of p15 emerged as a significant predictor
of a shorter overall survival (16,9 vs . 23,8 months, P=0,025; Logrank
test), whereas MGMT hypermethylation had no effect on median
overall survival (22,5 vs . 22,1 months, P=0,49; Log-rank test) . In the
presence of other clinically relevant factors (age, KPS, sex, MGMT),
p15 hypermethylation remains the only significant predictor (P=0,021;
Cox regression) .
Although these results need to be confirmed in larger series, our retrospective
study suggests that p15 hypermethylation can act as an
additional prognostic factor for survival in glioblastomas .
P04.150
Genetic basis in Gorlin syndrome
N. Alonso 1,2 , S. Ciria 1,2 , J. Mendioroz 3 , M. L. Martinez-Frías 3 , P. Unamuno 4 , R.
González-Sarmiento 1,2 ;
1 Unidad de Medicina Molecular-Departamento de Medicina. Universidad de
Salamanca, Salamanca, Spain, 2 Centro de Investigación del Cáncer, Salamanca,
Spain, 3 CIAC. Instituto de Salud Carlos III, Madrid, Spain, 4 Servicio de
Dermatología. Hospital Universitario de Salamanca, Salamanca, Spain.
Gorlin syndrome is an autosomal dominant disorder characterized by
multiple developmental abnormalities and predisposition to suffer tumours
. SHH receptor gene Patched1 has been directly related to Gorlin
syndrome . It represses Smoothened, which tranduces SHH signal
to activate transcription factor GLI family .
We have analyzed PTCH1 gene in 64 unrelated patients with Gorlin
syndrome, using PCR, heteroduplex and automatic sequencing . We
found 25 different mutations, 10 of them are reported for the first time:
IVS2(-2)delAGTTGGAGGACGAGTA; IVS5(-56) T>G; IVS6(+1)G>A;
IVS11(+20)delGAG; g .417insA; g .726delCA; g .1421insG; p .W851X;
p .P1050P and g .2517delC . We also searched for PTCH in 38 patients
by MLPA. We found 9 patients with amplifications and 3 cases with
deletions . Moreover, in cases without abnormalities in the PTCH1 locus,
we have analyzed new candidate genes in the SHH pathway:
We found 3 mutations (p .H262H; p .R509W; p .R531C) in GLI1 gene .
The 2 missense mutations have been secreened in 200 healthy controls
. R509W was found in one healtht subject, while R531C was not .
GLI2 analysis showed new intronic and silent mutations . We found 3
new missense mutations in CDON gene (p .I75V; p .E162K; p .A686V)
and 2 new missense changes in BOC gene (p .E915H and p .Q959K) .
All of them have been screened in 50 healthy controls resulting as
polymorphisms . Suppressor of Fused, EGFR and KCTD11 genes do
not present pathogenic mutations in patients with Gorlin syndrome .In
conclusion, 20 .3% of patients with Gorlin syndrome present mutations
in PTCH1 gene . We also conclude R531C mutation in GLI1 seems to
be pathogenic and responsible for Gorlin syndrome .
P04.151
Glutathione s-transferase (Gstm1) polymorphism in serbian
head and neck tumour patients
J. M. Milasin, B. Ilic, D. Jelovac, M. Pesic, A. Boro, V. Konstatinovic, M. Vukadinovic;
School of Dentistry, Belgrade, Serbia.
Susceptibility to head and neck tumours in a particular individual may
depend in part on the metabolic balance between Phase 1 enzymes,
such as cytochromes P450 (CYPs), and Phase II enzymes, such as
glutathione S-transferases (GSTs). Impaired detoxification of carcinogens
found in tobacco smoke appears to increase the risk for tobacco
associated cancers . Glutathione S-transferases (GSTs) are involved in
the metabolism of a wide range of carcinogenic chemicals . In humans,
cytosol GSTs are divided into several classes, and polymorphisms
of these enzymes are associated with variations in enzyme activity
which in turn may affect the concentration of activated carcinogenic
chemicals in the body . We have investigated the association between
the polymorphism in one of the cytosolic GSTs gene (GSTM1) and
susceptibility to oral squamous cell carcinoma (OSCC) and basal cell
carcinoma (BCC) of the skin . For that purpose 45 SCC, 42 BCC and
40 control specimens have been subjected to PCR analysis of the
GSTM1 gene . The frequency of GSTM null homozygous genotype
was as follows: 48% in BCCs, 44% in SCCs and 20% in controls . The
deletion of the GSTM1 gene was more frequent in SCC, than is controls
(p=0 .017) and the same was true for BCCs (p=0 .016) .
Although cytosolic glutathione S-transferase (GST) enzymes occupy
a key position in biological detoxification processes, GSTM1-1 gene
is deleted in a high percentage of the healthy human population, with
major ethnic differences. We found a significant difference in genotype
frequencies between the two tumour groups and healthy controls .
P04.152
molecular Assessment of chimersim after Allogeneic
Hematopoietic cell transplantation: clinical utility in monitoring
cell lineage engraftment
R. Domiati-Saad;
Baylor Univeristy Medical Center, Dallas, TX, United States.
Allogeneic hematopoietic cell transplantation (HCT) is a treatment option
for a variety of hematopoietic malignancies as well as nonmaligant
diseases . Monitoring of chimerism by molecular techniques has been
widely utilized in the routine clinical setting . Chimerism analysis is usually
performed on DNA extracted from unfractionated blood or bone
marrow samples. Analysis of lineage-specific leukocytes might be useful
in predicting the clinical outcome and might play a critical role in
the management of HCT patient. We have used an Analyte Specific
Reagent on a Beckman capillary electrophoresis platform to assess
the dynamics of chimerism within the individual leukocytes subsets
in 83 hematopoietic cell transplant patients after myeloablative and
nonmyeloablative regimens . Magnetic anti-CD3, anti-CD15 and anti-
CD19 beads were used to capture T cells, myeloid cells and B cells,
respectively, from peripheral blood and bone marrow samples prior to
isolation of DNA . Twelve different polymorphic short tandem repeats
(STR) loci were amplified in a single multiplex reaction. Chimerism
analysis performed on specific cellular lineages was most useful in
early detection of relapse than unfractionated whole blood analysis
due the increased sensitivity in the enriched cell subpopulations . Determination
of the level of donor T cells appears to be critical for successful
engraftment and could predict graft rejection .
P04.153
Hepatoblastoma: in vivo and in vitro models for the analysis of
Wnt/β-catenin and IGFs pathways
M. Salvatore1 , A. Antoccia2 , G. Azzalin3 , R. Devito4 , A. Di Masi2 , C. La Rocca5 ,
S. Lorenzetti5 , G. Macino3 , A. Magrelli3 , A. Mantovani5 , F. Maranghi5 , C. Tanzarella2
, S. Tait5 , R. Tassinari5 , F. Tosto1 , M. Viganotti1 , D. Taruscio1 ;
1Istituto Superiore di Sanità, Dept. of Cell Biology and Neuroscience, Rome,
Italy, 2University “Roma Tre”, Rome, Italy, 3University “Sapienza”, Rome, Italy,
4 5 Bambino Gesù Hospital, Rome, Italy, Istituto Superiore di Sanità, Dept. of
Food Safety and Veterinary Public Health, Rome, Italy.
Hepatoblastoma (HB) is the most important paediatric liver cancer (1%
in children aged 6mo-3yr) . HB is a multi-factorial condition including
both genetic and environmental factors .
Environmental factors may contribute to HB pathogenesis; exposure
to phthalates (i .e, diethyl-2-hexyl-phthalate-DEHP), present in PVCbased
devices, are suggested as a risk factor in the highly susceptible
subpopulation of premature and low-birth weight newborns . DEHP interacts
with nuclear receptors, thus interfering with a number of signalling
pathways .
To investigate the role of phthalate exposure, animal and cell line studies
are in progress to characterize the effects of DEHP, in comparison
with benzofuran, a HB inducer in aged mice . Furthermore, histological
and immuno-histochemical valuation will be performed on frozen and
paraffin-embedded human tissues from HB patients. To elucidate molecular
mechanism(s) of HB pathogenesis we will focus on i) the role of
Wnt/β-catenin and IGF pathways, and ii) its possible early diagnostic