12th Congress of the European Hematology ... - Haematologica

survival of five years. This dismal prognosis is mostly due to resistance
of MM to conventional therapies. Therefore, some of the attention has
been redirected toward studying the role of bone marrow microenvironment
in MM progression in order to find new ways to inhibit tumor
growth by blocking interaction between tumor cells and their microenvironment.
The important role of endothelium, osteoclasts and
osteoblasts in MM progression has been documented. Aims. In this study
we assessed the influence of myeloma-derived microvesicles (MMV) on
human mesenchymal stem cells (MSC) by stimulating them with MMV.
We compared also the gene expression profile in bone marrow stromal
cells (MSC) from four healthy subjects (hMSC) and from six MM
patients (mMSC). Methods. MMV were isolated from MM cell lines
supernatants. Expression level of mRNA for genes involved in angiogenesis,
invasion and MSC proliferation and osteoblastic differentiation
were evaluated using real-time RT-PCR. Results. hMSC were exposed to
30 mg/mL of MMV for 8 and 24 hours and changes in gene expression
were quantified. We noticed increased level of IL8 expression: 4.5 fold
after 8 hours and 2 fold after 24 hours stimulation. Upregulation of
MMP9 level was seen at 8 and 24 hours. HGF expression was decreased
by approximately 2 folds at both 8 and 24 hours. 8 - hour exposure to
MMV resulted in downregulation of RUNX2, collagen1 and osteocalcin
mRNA by 1.5, 3 and 2 folds, respectively. After 24 hours, level of RUNX2
and collagen1 remained constant and level of osteocalcin decreased to
3.5 folds. When we analyzed gene expression in mMSC in comparison
to hMSC we observed increased level of IL8 by 14 folds, VEGF and
MMP9 by 3 folds, and decreased level of HGF by 2 folds. Difference in
osteogenic genes expression in mMSC were also observed. RUNX2, collagen1
and osteocalcin were downegulated by 6, 11 and 5 folds respectively.
Conclusions. Our study showed that MMV can induce expression
of angiogenic and invasion genes and reduce expression of osteoblastic
genes in MSC. This suggests presence of pro-tumorigenic activators and
osteogenic inhibitors in MMV. Currently the biochemical composition
of MMV is being assessed. We also noticed that MSC isolated from MM
patients have skewed expression of several pro-tumorigenic and
osteogenic genes in comparison to healthy controls.
1006
DIFFERENTIAL EXPRESSION OF CD13 IN BONE MARROW COMPARTMENTS OF CD34 +
CELLS BETWEEN DIFFERENT GROUPS OF PATIENTS WITH MYELODYSPLASTIC
SYNDROMES
S. Matarraz, 1 A. Lopez, 1 C. Salvador, 2 N. Fernandez-Mosteirin, 2
M. Giralt, 2 A. Orfao1 1 Centro de Investigación del Cáncer, SALAMANCA, Spain; 2 Hematology ServiceMiguel
Servet Hospital, ZARAGOZA, Spain
Background. Aminopeptidase N (APN)/CD13 is a transmembrane protease
present in a wide variety of human tissues and cell types (endothelial,
epithelial, fibroblasts, leukocyte). This molecule is involved in extracellular
proteolysis, regulation of chemokine and cytokine activity, and
several other different cellular functions such us growth, secretion of
angiogenic molecules, motility and apoptosis. Expression of CD13 has
been shown to be deregulated in inflammatory as well as neoplastic diseases.
CD13 is overexpressed in acute and chronic myeloid leukemias
while information about its expression in myelodysplastic syndromes
(MDS) patients is currently limited. Objective. In the present study we
analyzed the expression of CD13 in normal myeloid CD34 + BM precursors
as well as in CD34 + cells from BM of patients with MDS in order to
evaluate the frequency of altered CD13 expression and its relationship
with the World Health Organization (WHO) and International Prognostic
Scoring System (IPSS) categories of MDS. Patient and methods. A total
of 73 BM samples corresponding to 23 healthy individuals (control
group), and 50 patients with newly diagnosed MDS were analyzed.
Patients were classified according to the WHO and IPSS criteria into:
refractory anemia (RA) (n=11), refractory cytopenia with multilineage
dysplasia (RCMD) (n=9), RA with excess of blasts (RAEB)-1 (n=13),
RAEB-2 (n=10), unclassifiable MDS (UNC) (n=2) and
myelodysplastic/myeloproliferative disorder (MDS/MPD) (n=5). Low
risk (LR) (n=12), intermediate risk (INT)-1 (n=14), INT-2 (n=9), and high
risk (HIGH) (n=4); in 11 cases karyotypic information was not available.
Among CD34 + BM cells three major cells subsets were identified: the
more immature CD34 + precursors (PRin), CD34 + /cyMPO + cells already
committed to neutrophil lineage (PRneu) and B-cell precursors. Expression
of CD13 was analyzed by flow cytometry in the former two compartments
of CD34 + precursors in terms of both percentage of CD13 +
cells and the amount of expression/cell of this protein. Results. As compared
to NBM, MDS patients showed overall increased percentages of
CD13 + /CD34 + cells associated with higher amounts of CD13 expression
12 th Congress of the European Hematology Association
in both the PRim and PRneu CD34 + cell subsets. Such increased CD13
expression was specifically observed for those groups of cases with a
poor outcome such as AREB-2 and HIGH risk MDS patients (p