2008 Barcelona - European Society of Human Genetics

Cancer genetics
such gene polymorphisms in predicting the occurrence of OSCC in
Europeans .
Methods: 330 Greeks and Germans were studied, consisting of 162
OSCC cases and 168 healthy controls of comparable age, gender, and
ethnicity . A series of multivariate logistic regression models, adjusted
for age and gender, was constructed in order to assess the contribution
of homozygous or heterozygous variant polymorphic genotypes
upon overall, early and advanced stages of OSCC development . The
studied polymorphisms included IL1b(+3953C/T), IL-4(-590C/T), IL-
6(-174G/C), IL-8(-251A/T), IL-10(-1082A/G), TNF-α(-308G/A) and
TNF-β(+252G/A), MMP-1(-1607 1G/2G), MMP-3(-1171 5A/6A), MMP-
9(-1562C/T), TIMP-2(-418C/G), VEGF(+936C/T), GPI-α(+807C/T),
PAI-1(4G/5G), ACE(intron 16D/I) and TAFI(+325C/T) .
Results: The contribution of TNF-α and IL-6 polymorphisms was consistent
and robust in almost all models constructed . Furthermore, when
the mode of inheritance of each variant allele was taken into account in
a multivariate logistic regression model, five polymorphisms emerged
as primary predictors for all OSCC stages: TIMP-2(OR=26 .33;
95%CI=12.39-55.95), TNF-α(OR=15.27; 95%CI=7.30-31.96), IL-
6(OR=8 .33; 95%CI=3 .95-17 .58), IL-8(OR=3 .54; 95%CI=1 .69-7 .43)
and IL-10(OR=2 .65; 95%CI=1 .28-5 .46) .
Conclusions: The highly significant contribution of 5 out of 16 studied
factors in the occurrence of OSCC was revealed . Based on these
findings and previous reports, possible interactions of the implicated
factors leading to OSCC development, as well as an algorithm of risk
estimation will be discussed .
P04.176
P53 and bcl-2 in the pathogenesis of oral squamous cell
carcinoma
B. Popovic 1 , I. Novakovic 2 , B. Jekic 2 , D. Jelovac 1 , B. Ilic 1 , V. Konstantinovic 1 , J.
Milasin 1 ;
1 School of Dentistry, Belgrade, Serbia, 2 School of Medicine, Belgrade, Serbia.
The imbalance between the rate of cell proliferation and apoptosis in
tumour tissue is due to numerous genetic and epigenetic factors . Two
of the most important cancer genes, contributing to pathogenesis of
oral squamous cell carcinoma (OSCC) are p53 and bcl-2 . Mutated
p53 gene is associated with the inability of the cell to repair DNA lesions
or to induce apoptosis . Consequently, increased expression of
the antiapoptotic marker bcl-2 in tumour cells is expected . Based on
this regulation pathway, in the present study we analyzed the association
between the presence of mutated p53 gene and expression
of bcl-2 protein . Mutational analysis of exons 5-8 of p53 was done
by SSCP followed by sequencing . Expression of bcl-2 was analyzed
by immunohistochemistry . According to results of mutational and immunohistochemical
analyses, performed on 28 specimens of OSCCs,
60% of samples showed simultaneously the presence of mutated p53
gene and expressed bcl-2 oncoprotein . Independently of p53 status,
the expression of bcl-2 was detected in 68% cases . Both analyzed
markers showed an increased rate of mutation/expression in tumors
of higher clinical stages .
The positive association between changes in p53 and bcl-2, point
at deep deregulation of apoptosis which is in agreement with the increased
proliferative potential of OSCCs .
Routine analysis of these markers in tumour samples obtained after
surgery might be valuable in the assessment of tumour aggressiveness
.
P04.177
intratumoral patterns of clonal evolution in Ductal Pancreatic
Adenocarcinoma by multicolour interphase fluorescence in situ
hibridization (iFisH).
M. L. Gutiérrez1 , L. Muñoz-Bellvis2 , J. M. Sayagues1 , O. Bengoechea3 , M. M.
Abad3 , A. Orfao1 ;
1Servicio General de Citometría, Centro de Investigación del Cáncer, Universidad
de Salamanca, Salamanca, Spain, 2Unidad de Cirugía Hepática,
Biliar y Pancreática, Hospital Universitario de Salamanca, Salamanca, Spain,
3Departmento de Anatomía Patológica, Hospital Universitario de Salamanca,
Salamanca, Spain.
Introduction . Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease
with an almost uniform 5-year mortality rates . Understanding the
molecular mechanisms involved in tumor development and progression
are a prerequisite to improve early diagnosis and therapy . How-
ever no study has been reported so far in which the clonal evolution
of tumor cells has been systematically analyzed at the intratumoral
cell level .
Materials and methods . Chromosomal abnormalities for 46 chromosomal
regions distributed across the most frequently altered chromosomes
were studied in 29 PDAC patients using multicolor interphase
FISH techniques .
Results . All cases displayed numerical/structural abnormalities for at
least one of the 24 chromosomes analyzed . Chromosome 17 was the
most frequently altered (27/29 cases), followed by chromosomes 18
(23/29), 8 and 9 (24/29), and chromosome Y (17/21); in contrast, chromosome
22 was the less frequently altered . Of note, monosomy 9/9p-
was positively associated with 17p and 18q deletions . Overall, only
3 (7%) of the 29 cases analyzed had a single tumor cell clone while
most cases (93%) displayed two or more clones . The most frequent
ancestral tumor cell clones were characterized by deletion of 9p, 17p,
18q and Y nulisomy .
Conclusions . Our results show that, as in other tumors, progression
of PDAC is a multi-step process in which neoplastic cells develop genome-wide
instability evidenced at the intratumoral cell level leading
to the emergence of multiple clonal populations with different chromosome
abnormalities within the same tumor . This study also provides
evidence about different patterns of intratumoral clonal evolution which
had not been previously reported .
P04.178
Genetic variation and haplotype structures of the gene encoding
human thymidylate synthase, a pharmacogenetic marker in
fluoropyrimidine-treated cancer patients
M. Baiget, L. Paré, E. del Rio, P. Gallano, E. Tizzano, J. Salazar;
Genetics. Hospital Sant Pau, Barcelona, Spain.
Thymidylate synthase (TS) activity is an important determinant of response
to chemotherapy with fluoropyrimidine prodrugs and its expression
is largely determined by polymorphic features in the 5’ UTR region
of the TS gene that can modify the number of the functional USF protein
binding sites . DNA was extracted from peripheral blood from 587
caucasian cancer patients . Genotyping was performed by PCR amplification
of the repeat region followed by automated sequencing
Results:
# Functional
USF
binding sites
1
Genotypes*
Colorectal cancer
N (%)
Breast cancer
N (%)
2RGC/2RCC 0 (0 .0) 1 (0 .6)
2RCC/3RGCC 3 (0 .7)) 0 (0 .0)
2RGC/2RGC 75 (17 .8) 40 (24,1)
3RGCC/3RGCC 44 (10 .6) 13 (7,8)
2RGC/3RGCC 103 (24 .5) 45 (27,1)
2
2RCC/3RGGC
2RGC/
3RGCC+ins6pb
2 (0 .5)
4 (1 .0)
0 (0 .0)
1 (0 .6)
3RGCC/
3RGCC+ins6bp
3 (0,7) 2 (1 .2)
3RGGC/3RGCC 75 (17 .8) 25 (15 .1)
2RGC/3RGGC 73 (17 .3) 27 (16 .3)
3
2RGc+ins4bp/
3RGGC
1 (0 .2) 0 (0 .0)
3RGGC/
3RGCC+ins6bp
3 (0 .7) 0 (0 .0)
3RGGC/3RGGC 32 (7 .6) 12 (7 .2)
4
2RGG/3RGGC
2RGC/4RGGGC
1 (0 .2)
1 (0 .2)
0 (0 .0)
0 (0 .0)
3RGGC/4RGGCC 1 (0 .2) 0 (0 .0)
Total N: 421 Total N: 166
In bold: novel allele. *According to Lincz et al. Int. J. Cancer 2007; 120:1930-34.
We define the genotypes of the 5’UTR region of the TS gene in a large cohort of caucasian
cancer patients and we determine the number of functional USF binding sites
that can be used as a pharmacogenetic marker in patients treated with fluoropyrimidines.
The recently described 2RCC allele was also found in 6 patients, in all cases in
heterozygous form. We identify a novel allele containing a 4bp insertion (cgcc) in the
inverted repeat sequence located 2bp prior to the ATG start codon.
Grant support: Fondo de Iinvestigaciones Sanitarias (FIS 05-1218). CIBERER, Barcelona
Spain.