2009 Vienna - European Society of Human Genetics
2009 Vienna - European Society of Human Genetics
2009 Vienna - European Society of Human Genetics
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Cancer genetics<br />
P06.177<br />
somatically acquired JAK mutations in adult acute<br />
lymphoblastic leukemia<br />
E. Flex 1 , V. Petrangeli 1 , L. Stella 2 , S. Chiaretti 3 , T. Hornakova 4 , L. Knoops 4 , F.<br />
Paoloni 3 , V. Cordeddu 1 , M. Sanchez 1 , G. Cazzaniga 5 , A. Tornesello 6 , M. Vignetti<br />
3 , J. Renauld 4 , A. Biondi 5 , S. N. Constantinescu 4 , R. Foà 3 , M. Tartaglia 1 ;<br />
1 Istituto Superiore di Sanità, Rome, Italy, 2 Università “Tor Vergata”, Rome, Italy,<br />
3 Università “La Sapienza”, Rome, Italy, 4 Université catholique de Louvain, Bruxelles,<br />
Belgium, 5 Università di Milano Bicocca, Monza, Italy, 6 Università Cattolica<br />
del Sacro Cuore, Rome, Italy.<br />
Aberrant signal transduction contributes substantially to leukemogenesis.<br />
Here, we report that somatic mutations in the Janus kinase 1<br />
(JAK1) gene, which encodes a cytoplasmic tyrosine kinase that noncovalently<br />
associates with a variety <strong>of</strong> cytokine receptors and plays<br />
a nonredundant role in lymphoid cell precursor proliferation, survival<br />
and differentiation, occur in individuals with acute lymphoblastic leukemia<br />
(ALL). JAK1 mutations were more prevalent among adult subjects<br />
with T-cell precursor ALL, where they accounted for 18% <strong>of</strong> cases,<br />
and were associated with advanced age at diagnosis, poor response<br />
to therapy and overall prognosis. All mutations were missense, some<br />
predicted to destabilize interdomain interactions controlling the activity<br />
<strong>of</strong> the kinase. Three mutations that were studied promoted JAK1 gain<br />
<strong>of</strong> function, and conferred interleukin 3-independent growth in Ba/F3<br />
cells and/or interleukin 9-independent resistance to dexamethasoneinduced<br />
apoptosis in T cell lymphoma BW5147 cells. Such effects<br />
were associated with variably enhanced activation <strong>of</strong> multiple downstream<br />
signaling pathways. Leukemic cells with mutated JAK1 alleles<br />
shared a gene expression signature characterized by transcriptional<br />
upregulation <strong>of</strong> genes positively controlled by JAK signaling. Our findings<br />
implicate dysregulated JAK1 function in ALL, particularly <strong>of</strong> T-cell<br />
origin, and point to this kinase as a target for the development <strong>of</strong> novel<br />
anti-leukemic drugs.<br />
P06.178<br />
study <strong>of</strong> the effect <strong>of</strong> mRP1 gene polymorphisms on its mRNA<br />
expression in acute leukemic patients<br />
S. Rezvani, F. Mahjubi, M. Montazeri;<br />
National Institute <strong>of</strong> Genetic Engineering&Biotechnology(NIGEB), Tehran, Islamic<br />
Republic <strong>of</strong> Iran.<br />
One <strong>of</strong> the major problems in treating cancer cells is that they can<br />
acquire drug resistance (so called Multidrug Resistance: MDR). There<br />
are several mechanisms responsible for MDR. One <strong>of</strong> the most important<br />
is the overexpression <strong>of</strong> ABC transporter genes. One <strong>of</strong> the most<br />
extensively studied genes involved in MDR is multidrug resistance protein<br />
1 (MRP1). We have shown that the overexpression <strong>of</strong> this gene is<br />
associated with the MDR in Iranian leukemic patients. However, MRP1<br />
gene amplification could not be identified in any <strong>of</strong> those patients. Another<br />
mechanism is the influence <strong>of</strong> the MRP1 gene polymorphisms on<br />
the expression level <strong>of</strong> the gene.<br />
We aimed to investigate the possible association between the expression<br />
level <strong>of</strong> MRP1 and occurrence <strong>of</strong> MDR in leukemic patients. Furthermore,<br />
we wished to test the hypothesis that MRP1 polymorphisms<br />
would be predictive <strong>of</strong> MDR in patients with acute leukemia. mRNA<br />
level <strong>of</strong> MRP1 was determined in 111 patients with acute leukemia<br />
(including 52 patients with AML and 59 patients with ALL) by quantitative<br />
real time RT-PCR and compared to the type <strong>of</strong> response to<br />
chemotherapy.<br />
We typed G816A,T825C,G2168A,C2217T,G2268A,G1299T,G-260C,<br />
A-275G MRP1 polymorphisms in those patients classified either drugresistant.<br />
We found that high expression <strong>of</strong> MRP1 was associated with<br />
MDR phenotype in both AML and ALL patients. There was no effect <strong>of</strong><br />
a particular genotype on the expression level <strong>of</strong> the MRP1 gene. This<br />
could show the lack <strong>of</strong> dependency <strong>of</strong> any <strong>of</strong> these genotypes on the<br />
chemosensivity in this group <strong>of</strong> patients.<br />
P06.179<br />
Expression analysis <strong>of</strong> the mitogenic growth factor receptors<br />
in childhood acute myeloid leukemia; increased Expression <strong>of</strong><br />
Vascular Endothelial Growth Factor Receptor-1 and the Loss <strong>of</strong><br />
Estrogen Receptor beta<br />
F. Atalar 1 , T. A. Tekiner 2 , S. Anak 3 , U. Ozbek 4 ;<br />
1 Istanbul University, Istanbul Medical Faculty, Child Health Institute, Pediatric<br />
Endocrinology Department, Istanbul, Turkey, 2 Istanbul Technical University,<br />
Molecular Biology and <strong>Genetics</strong> Department, Istanbul, Turkey, 3 Istanbul University,<br />
Istanbul Medical Faculty, Department <strong>of</strong> Pediatric Hematology and Oncology,<br />
Istanbul, Turkey, 4 Istanbul University, Institute <strong>of</strong> Experimental Medical<br />
Research (DETAE), <strong>Genetics</strong> Department, Istanbul, Turkey.<br />
Constitutive PI3K/Akt/mTOR signaling is upregulated by the activating<br />
mutations <strong>of</strong> receptor tyrosine kinases, autocrine/paracrine secretion<br />
<strong>of</strong> growth factors and estrogens triggering the binding <strong>of</strong> ERα to<br />
PI3K and ERβ to AKT.Mutational analysis <strong>of</strong> FLT3 together with the<br />
expression analysis <strong>of</strong> VEGF receptors, estrogen receptors and IGF<br />
system were performed in pediatric AML (pAML) patients and controls,<br />
CD33+ cells isolated from healthy bone marrows.FLT3/ITD and FLT3/<br />
D835 mutations have been identified in 12% and 2 % <strong>of</strong> 50 pAML<br />
patients respectively.Flt-1 and KDR expression were determined to be<br />
significantly higher in pAML patients.ERα expression was observed in<br />
54.5% <strong>of</strong> the patients where diminished ERβ expression was determined.The<br />
results <strong>of</strong> the IGF system genes expression studies indicated<br />
higher IGF-1 expression(16.3 fold), and significantly lower IGF-2<br />
and IGF-1R expressions in pAML patients.IGFBP-rP1 expression was<br />
10.48 fold lower in pAML patients.Expression studies <strong>of</strong> initiator caspases,<br />
caspase8 and caspase9 revealed low level <strong>of</strong> caspase9 and<br />
increased level <strong>of</strong> caspase8(13.6 fold) expression in pAML patients.<br />
IGFBP-rP1 and caspase8 expressions were also evaluated by western<br />
blot analysis in pAML samples.Upregulation <strong>of</strong> PI3K/Akt pathway<br />
through altered expression levels <strong>of</strong> upstream mitogenic growth factors<br />
and their receptors were also confirmed by altered expression<br />
levels <strong>of</strong> Akt downstream genes; c-myc and cyclin D1 as a result <strong>of</strong><br />
GSK3ß phosphoinhibition in pAML patients.To our knowledge this is<br />
the first data representing the loss <strong>of</strong> ERβ gene expression in pediatric<br />
AML patients.Our study showed that IGF-1 and caspase8 could be<br />
potential antiapoptotic markers and IGFBP-rP1 a new tumor suppressor<br />
in pAML.<br />
P06.180<br />
study <strong>of</strong> suz12 gene expression in chronic myelogenous<br />
leukemia patient<br />
M. Ghalandary 1 , B. Hassannia 1 , M. Behmanesh 1 , M. T. Akbari 2 ;<br />
1 Department <strong>of</strong> <strong>Genetics</strong>, Faculty <strong>of</strong> Basic Science,Tarbiat Modares University,<br />
Tehran, Islamic Republic <strong>of</strong> Iran, 2 Department <strong>of</strong> Medical <strong>Genetics</strong>, Faculty <strong>of</strong><br />
Basic Science,Tarbiat Modares University, Tehran, Islamic Republic <strong>of</strong> Iran.<br />
Polycomb group proteins are transcriptional repressors that play a<br />
central role in the establishment and maintenance <strong>of</strong> gene expression<br />
patterns during development. Trimethylation <strong>of</strong> histone H3 on lysine<br />
27, mediated by a PcG protein complex consisting <strong>of</strong> Eed, Ezh2, and<br />
Suz12, is integral in differentiation, stem cell self-renewal, and tumorigenesis.<br />
Deregulated activity <strong>of</strong> the chromatin remodeling Polycomb<br />
Repressive Complex 2 (PRC2) has recently been shown to be a frequent<br />
event in human tumors. Recent study shows that loss <strong>of</strong> Suz12, a<br />
core component <strong>of</strong> Polycomb Repressive Complex 2 (PRC2), function<br />
enhances hematopoietic stem cell (HSC) activity. Their study suggests<br />
that PRC2 is required to maintain a specific gene expression pattern<br />
in hematopoiesis that is indispensable to normal stem cell function.<br />
Chronic myelogenous leukemia (CML) is a clonal myeloproliferative<br />
disorder <strong>of</strong> the hematopoeitic stem cell (HSC).<br />
In this study the expression level <strong>of</strong> Suz12 gene was compared between<br />
CML patiens and control group. In this report we will present the<br />
obtained results.<br />
P06.181<br />
Fluorescence in situ Hybridization Analysis <strong>of</strong> the htERc<br />
Region in Acute myeloid Leukemia Patients<br />
O. Ozer, T. Bulakbasi Balci, Z. Yilmaz, F. I. Sahin;<br />
Baskent University Faculty <strong>of</strong> Medicine Department <strong>of</strong> Medical <strong>Genetics</strong>, Ankara,<br />
Turkey.<br />
Telomerase is a ribonucleoprotein complex consisting <strong>of</strong> reverse<br />
transcriptase (hTERT), proteins (hTP1) and RNA template for telomeric<br />
DNA synthesis (hTERC). The telomerase RNA component<br />
(TERC) gene is located at 3q26. Increased TERC gene dosage has<br />
been detected frequently in a variety <strong>of</strong> human cancers, suggesting<br />
a growth advantage in cells with increased gene dosage. Amplification<br />
was shown by fluorescence in situ hybridization (FISH) in different<br />
cancers. It has been suggested that the activation <strong>of</strong> telomerase<br />
in leukemic cells may be connected with amplification <strong>of</strong> hTERT and<br />
hTERC genes. The aim <strong>of</strong> this study was to investigate whether there<br />
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