2008 Barcelona - European Society of Human Genetics

Cancer genetics
genesis and cancer progression . Mutations in TP53 are considered to
represent the most common genetic alteration and occur in about 50%
of human cancers . These mutations may damage the normal function
of p53 as a transcription factor and the induction of repair or apoptosis
may be diminished . Consequently, genetic alterations may accumulate
in the cell .
Evidences from previous studies imply that there is a clear correlation
between mutational status of TP53 and expression of gens down the
p53-signaling pathway .
We examined the impact of mutations in DNA binding domain of p53
on expression of genes involved in cell cycle arrest, particularly CDK4
and its inhibitor CDKN2 .
This study included bioptic samples from 80 breast and colon cancer
affected subjects with different malignancy grades .
To test hypothesis that mutation in TP53 can influence expression of
CDK4 and CDKN2, TP53 has been subjected to mutational analysis
by RFLP followed by sequencing .
Expression of genes involved in cell cycle arrest was measured using
SYBR-green based real-time PCR .
Mutations in TP53 were detected in 8% of the examined cases .
We compared expressions of CDK4 and CDKN2 in the samples that
harbor a mutation to those without mutations .
Pathohistological findings obtained from clinic were correlated with
molecular alterations .
P04.203
Association study of codon 10 polymorphism of the
Transforming growth factor-beta 1 (TGF-β1) gene with prostate
cancer and hyperplasia
M. Omrani, S. Bazargani, S. Salari, B. Farshid;
Uromieh Medical Science University, Uromieh, Islamic Republic of Iran.
Introduction: Transforming growth factor-beta 1 (TGF-β1) has a multifactorial
role in the development of cancer . Genetic polymorphisms
in codons 10 of the TGF-β1 gene have been shown to be associated
with the production of high or low TGF-β1 levels. The role of this polymorphism
in development of prostate cancer and hyperplasia was investigated
.
Material and Methods:Using ASO-PCR method, association between
the T (Leu) to C (Pro) polymorphism at codon10 of the TGF-ß1 gene
(TGFB1) and the risk of PCa or BPH in 100 controls were determined
.
Results: Significant differences in the CC versus TT genotype distribution
between PCa patients and male controls (P = 0 .009), and between
BPH patients and male controls (P = 0 .005) were noticed . Males with
the TT genotype had a 1.67-fold increased risk of PCa [95% confidence
interval (95% CI) = 1 .49-1 .87, P = 0 .009] and TC /TT genotype,
1.14-fold increased risk of PCa [95% confidence interval (95% CI) =
1 .02-1 .26, P = 0 .047] and a 1 .54-fold increased risk of BPH with the
TT genotype (95% CI = 0 .98-1 .14, P = 0 .005) and 1 .06-fold increased
risk of BPH with the TT/TC genotype (95% CI = 0 .98-1 .14, P = 0 .061)
compared with those with the CC genotype respectively .
Conclusion: Based on our findings, it was possible to conclude that the
codon10 polymorphism in TGFB1 may have a significant influence on
the development of PCa and BPH and the T allele of TGFB1gene has
the dominant effect on development of PCa and BPH .
P04.204
subtle microsatellite instability in pediatric gliomas as an
indicator of type 1 turcot syndrome
L. Giunti 1 , V. Cetica 2 , U. Ricci 1 , S. Giglio 3 , I. Sardi 2 , M. Paglierani 4 , A. Buccoliero
4 , L. Genitori 5 , M. Genuardi 3,1,4 ;
1 Medical Genetics Unit, Meyer Children’s University Hospital, Florence, Italy,
2 Department of Pediatrics, University of Florence, Florence, Italy, 3 Medical
Genetics Unit, Department of Clinical Pathophysiology, Florence, Italy, 4 Department
of Biomedicine, Careggi University Hospital, Florence, Italy, 5 Neurosurgery
Unit, Meyer Children’s University Hospital, Florence, Italy.
Type 1 Turcot syndrome (TS1) is characterized by the association of
early-onset glial and colorectal tumors and is caused by mutations of
the mismatch repair genes . To determine the role of genetic predisposition
in glial tumor development, we investigated the frequency of
microsatellite instability (MSI) in a series of 38 pediatric gliomas using
a panel of 5 quasimonomorphic mononucleotide markers . A pattern of
“subtle” MSI for most tested markers was observed in 2 glioblastomas .
In both cases family history was indicative of TS1, as confirmed by the
detection of mutations in the PMS2 and MLH1 genes . In one case,
instability was revealed in diluted DNA samples . Comparison of the
MSI patterns in normal (leukocyte and intestinal mucosa) and tumor
(glioblastoma and colorectal cancer) samples from one TS1 family
revealed that allelic size shifts were smaller in gliomas . Our results
indicate that MSI analysis is an important tool to identify TS1-related
pediatric gliomas, and that the pattern of microsatellite alterations in
gliomas is less pronounced compared to colorectal cancer
P04.205
Analysis of the molecular genetic changes in uveal melanoma
I. K. Manokhina 1 , N. V. Sklyarova 2 , S. V. Saakyan 2 , D. V. Zaletaev 1 ;
1 Laboratory of human molecular genetics, Institute of Molecular Medicine, I.M.
Sechenov Moscow Medical Academy, Moscow, Russian Federation, 2 Ophthalmo-oncology
and radiology department, Helmholts Moscow Research Institute
of Eye Diseases, Moscow, Russian Federation.
Uveal melanoma (UM) is the most common primary cancer of the eye
and has a strong predilection for hematogenous metastasis, particularly
to the liver. Investigation of the specific genetic mechanisms responsible
for the malignant behavior of UM could play an important role for
the development of new approaches to UM diagnosis and treatment .
We investigated 105 UM for allelic losses at chromosomal regions 3p,
3q, 1p, 9p23, 10q23, 13q14, close or within some tumor suppressor
genes (VHL, FHIT, RASSF1A, CDKN2A, PTEN, RB1) . Moreover, we
investigated the methylation status of the promoter regions of these
genes .
45 UM (43%) had LOH at all informative loci of chromosome 3, indicating
of monosomy 3 . Methylation analysis discovered frequent methylation
of RASSF1A (24 patients, 23%), located at 3p21 .3 and inactivated
in a large number of human cancers . Important to notice, methylation
of RASSF1A was found predominantly in UM without monosomy 3 (20
patients). These findings could reinforce the role of RASSF1A in the
pathogenesis of UM .
LOH at 1p was found in 28 samples mainly at all informative loci (5 MS
markers, 1p31 .3 to 1p36 .3) without any relation to the monosomy 3 .
Five samples had partial allelic losses at 1p31 .3 or 1p36 .3 . 1p contains
wide range of TSGs, and for the moment we could not identify those
who might be candidate genes for the UM .Additionally, we conclude
that inactivation of the regulation pathway CDKN2A→RB1 with promoter
methylation or LOH is not the major mechanism of the pathogenesis
in UM unlike cutaneous melanoma .
P04.206
VANGL1 effects cell invasion rather than cell motility
O. Cetin 1 , A. Toylu 2 , N. Atabey 2 , Z. Sercan 2 , M. Sakizli 2 ;
1 Pamukkale University, School of Medicine, Department of Medical Biology,
Denizli, Turkey, 2 Dokuz Eylul University, School of Medicine, Department of
Medical Biology and Genetics, Izmir, Turkey.
Van Gogh like 1 (Vangl1) is a transmembrane protein on Wnt planar cell
polarity pathway . It has an important role in planar cell polarity and convergent
extension in embryonic development . In adults, it is expressed
specifically in testis and ovaries as well as in brain and prostate.VANGL1
expression has been shown in several human cancer cell lines including
hepatocellular carcinoma (HCC) . Our aim in this study was to investigate
the changes in the behaviour of the HCC cells whose VANGL1 gene was
silenced by siRNA .
VANGL1 expression in HCC cell lines was shown by RT-PCR and real
time PCR. The siRNA template which will transcribe the specific hairpin
siRNA for VANGL1 gene was designed following the determination of the
target sequence . The siRNA template was ligated to a siRNA expression
vector and HepG2 cells were transfected . The colonies expressing the
siRNA were detected by RT-PCR, quantitative RT-PCR and Western blotting
. Motility and invasion of the cells were assessed by Boyden chamber
assay while cell cycle analysis was performed by flow cytometry.
The motility of the cells was not effected with gene silencing while there
was a three fold decrease in the invasion potential of the cells expressing
the siRNA. The proliferation assay revealed no significant difference
between the transfected cells and parental cells with regard to S phase
cell ratio .
In conclusion, VANGL1 gene has an effect on cell invasion rather than
cell motility . Further investigations are needed to understand the mechanisms
of this effect .