2008 Barcelona - European Society of Human Genetics

Cancer genetics
P04.050
chromosomal aberrations in Breast cancer patients in
tamilnadu Region
R. Sangeetha, V. Balachandar, B. LakshmanKumar, K. Suresh, K. Sasikala;
Human Genetics Laboratory, School of Life Sciences, Bharathiar University,
Coimbatore, India.
Breast cancer is the most common cancer in women and accounts for
between 18-25% of all female malignancies world-wide . In India, the
incidence of breast cancer is increasing, with an estimated 80,000 new
cases diagnosed annually . The frequency of chromosome instability
in peripheral blood lymphocytes is relevant biomarker for cancer risk
in humans. So, the present investigation aimed to find out the major
chromosomal alteration in breast cancer patients in Tamilnadu region
by using the conventional karyotyping method . In the present study 63
experimental subjects were selected on the basis of CA15 .3 marker
which is the most widely used serum biochemical tumor marker in
breast cancer and equal number of controls were selected and confirmed
by CA53 level. The work was carried out in accordance with the
ethical standards laid down in the 1964 Declaration of Helsinki . After
signing a consent form, both cases (experimentals and controls) provided
a blood sample (5 ml) to establish the 72hrs cell cultures .
In the present study deletion and translocation were frequently observed
in chromosome 1, 11 and 17 . (46, XX, del (1p - ); 46, XX, del
(11q - ); 46, XX, del (17q - ) . 46, XX, t (1q +; 16q - ) ; 46, XX, t (11q +; 7p - ) ; 46,
XX, t (17q +; 4q - )) .
In the near future, we can look forward to the identification of novel
breast cancer predisposing genes due to rapid advancement of gene
discovery technologies. The Identification and functional characterization
of such genes will have a significant impact on breast cancer
research and early detection .
P04.051
characterization of novel large genomic rearrangements in the
BRCA / genes of Spanish families with breast/ovarian cancer
S. Palanca 1 , E. Esteban 1 , I. de Juan 1 , E. Barragán 1 , S. Oltra 2 , I. Chirivella 3 , Á.
Segura 4 , C. Guillén 5 , E. Martínez 6 , P. Bolufer 1 ;
1 Lab. Biología Molecular. Hospital U. La Fe, Valencia, Spain, 2 Unidad de Genética.
Hospital U. La Fe, Valencia, Spain, 3 UCGC Hospital Clínico Universitario,
Valencia, Spain, 4 UCGC Hospital U. La Fe, Valencia, Spain, 5 UCGC Hospital
General de Elche, Alicante, Spain, 6 UCGC Consorcio Hospital Provincial, Castellón,
Spain.
Background: Mutations in BRCA1/2 genes affecting a small number
of nucleotides are the responsible for the majority (90%) of hereditary
breast and/or ovarian cancers (HBOC) . However, there is an increasing
evidence of the contribution of large genomic rearrangements
(LGRs) of BRCA1/2 genes to HBOC .
The purpose of this study is to characterize the novel LGRs identified
in BRCA1/2 genes and determine its prevalence in families studied
in Program of Genetic Counselling on Cancer of the Valencian Community
(Spain) .
Method: We used the multiplex ligation-dependent probe amplification
(MLPA) to screen for LGRs in 255 unrelated index patients with familial
breast and/or ovarian cancer negative for BRCA1/2 mutations . Characterization
of the LGRs was carried out by performing long-range
PCR followed by sequencing .
Results: Nine different LGRs were identified in once index patients out
of the 225 (4 .3%), seven in BRCA1 and two in BRCA2 . Five BRCA1
LGRs have been already reported (1A/1B and 2 deletion; 5 to 7 deletion;
8 to 13 deletion, exon 20 deletion and amplification of exon 20)
and also four novel LGRs were found . Characterization of the novel
mutations revealed the presence of deletions that encompass exons 3
to 5 of BRCA1, partial deletion of exon 21 of BRCA1, deletion of exons
22 to 24 of BRCA2 and deletion of exon 2 of BRCA2 gene .
Conclusions: These findings contribute to broaden the spectrum of
LGRs described in the BRCA1/2 genes . Additionally, our data emphasize
the relevance of LGRs in the mutational study of BRCA1/2 genes
of high-risk families .
P04.052
UNc5 genes and breast cancer: a mutation screening and LOH
analysis
E. Bonora 1 , C. Evangelisti 1 , I. Kurelac 1 , M. Vargiolu 1 , D. Fusco 1 , A. Bernet 2 , P.
Mehlen 3 , G. Romeo 1 ;
1 Unit of Medical Genetics, Bologna, Italy, 2 CNRS UMR 5238 Laboratoire Apoptose,
Cancer et Développement, Centre Léon Bérard,, Lyon, France, 3 CNRS
UMR 5238 Laboratoire Apoptose, Cancer et Développement, Centre Léon
Bérard, Lyon, France.
Dependence Receptors (DR) display the common feature of inducing
two completely opposite intracellular signals: in the presence of
the ligand, they transduce a positive survival signal, whilst in its absence,
they induce apoptosis . The three mammalian receptors named
UNC5A, UNC5B, and UNC5C in human, belong to the family of the
netrin-1 receptors, act as mediators of netrin-1 chemorepulsive effect
during neural development, but also work as dependence receptors .
Expression of human genes is down-regulated in multiple cancers including
colorectal and breast cancers . In colorectal tumors, this downregulation
is associated with loss of heterozygosity (LOH) . In order to
verify the possible LOH in breast cancer, a panel of 57 breast tumors
were analysed for these genes using intragenic microsatellite markers,
but no LOH was detected . Since mutations impairing mRNA or
protein levels would not have been detected by LOH analysis only,
a mutation screening of PCR amplified exons is currently ongoing. In
UNC5B a new variant was identified in exon 10, T1909C, which results
in a silent substitution in the protein but by in silico analysis affects an
exon splicing enhancer (ESE), which could modify mRNA processing .
The change is now tested in a panel of 100 controls . Depending on the
results obtained, the variant will be further investigated using a splicing
assay with a synthetic minigene. The analysis is still ongoing and final
results will be presented .
P04.053
misbehaviour of Xist RNA in breast cancer cells
S. M. Tabano 1 , L. Monti 1 , M. Recalcati 2 , M. Gariboldi 3 , F. R. Grati 4 , P. Finelli 2,5 , P.
Radice 3,6,6 , M. Miozzo 1 , S. M. Sirchia 1 ;
1 Genetica Medica, Dip. di Medicina, Chirurgia e Odontoiatria, Università di
Milano, Milan, Italy, 2 Laboratorio di Citogenetica Medica e Genetica Molecolare,
Istituto Auxologico Italiano, Milan, Italy, 3 Istituto FIRC di Oncologia Molecolare
(IFOM), Milan, Italy, 4 Citogenetica e Biologia Molecolare, Laboratorio Toma,
Busto Arsizio, Italy, 5 Dipartimento di Biologia e Genetica per le Scienze Mediche,
Università di Milano, Milano, Italy, 6 Dip. di Oncologia Sperimentale, Istituto
Nazionale Tumori, Milano, Italy.
Recently, a strong open debate has been dragging on about the role of
the BRCA1 in the XCI (X chromosome inactivation) process and about
the meaning of the “Disappearing Barr Body” observed in breast and
ovarian cancer. A definitive answer about the hypothetical function of
BRCA1 in the correct localization of XIST RNA on the inactive X chromosome
(Xi) hasn’t been found yet, while it’s known that in breast cancer,
especially with basal like phenotype, can be frequently observed
X chromosome anomalies, mainly Xi loss associated to replication of
the active X chromosome (Xa) .
We investigated some aspects to further sound out the supposed link
between BRCA1 and XIST expression/localization . In addition, we tested
the possibility of XIST RNA to associate with a different target than
Xi, in presence of anomalous XCI status, a common feature of breast
carcinomas . The study was performed on tumor cell lines and breast
carcinomas by a combined genetics and epigenetics approach .
We drown the following conclusions: i) high levels of XIST RNA were
observed as a marker of BRCA1-associate BLC; ii) BRCA1 was involved
in regulation of XIST expression on the Xa, but we confirmed
the absence of a link between BRCA1 and XIST nuclear distribution;
finally, we surprisingly surveyed in breast cancer cells the ability of
XIST RNA to decorate an active X chromosome, demonstrating that
the presence of focal XIST staining in the nucleus does not prove the
existence of an inactive X chromosome .
P04.054
Genetic peculiarities of families with inherited bilateral breast
cancer
N. I. Pospekhova 1 , L. N. Lubchenko 2 , A. N. Loginova 1 , E. V. Poddubskaya 2 , R.
F. Garkavtseva 2 , A. V. Karpukhin 1 ;
1 Research Centre For Medical Genetics, Moskow, Russian Federation, 2 Cancer
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