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

Methods. Several read-out systems were used in this study including RT-
PCR, flow cytometry, Western blotting and phosphorylation assay.
Results. Ror-1 was expressed at the gene and protein levels in leukemic
B cells of all B-CLL patients (n=100). Ror1 was not expressed in leukocytes
from healthy individuals, enriched B cells, T cells, and granulocytes
but weakly in normal tonsil B cells. A strong activation signal
(PMA/Ionomycin) induced expression of Ror1 in normal lymphocytes.
Five different variants of the Ror1 protein were identified, ranging from
68 to 105 kDa (68, 85, 96, 102, and 105). The 102 and 105 kDa isoforms
may represent the native Ror-1 molecules and were differentially
expressed in progressive and non-progressive disease. The 68, 85, and 96
kDa isoforms were auto-phosphorylated but not the 102 and 105 kDa
variants. Conclusions. The ectopic expression of auto-phosphorylated
Ror1 in CLL, indicate a potential role of this RTK in the pathobiology of
B-CLL.
0513
GENE EXPRESSION COMPARISON BETWEEN B CELLS EXPRESSING HIGH AND LOW
LEVEL OF ZAP-70 MRNA REVEALS DISTINCT PROFILES, POTENTIAL THERAPEUTIC
TARGETS AND NEW PROGNOSTIC FACTORS FOR CHRONIC LYMPHOCYTIC LEUKEMIA
B. Stamatopoulos, C. Equeter, B. Haibe-Kains, A. Soree, C. Sotiriou,
D. Bron, P. Martiat, L. Lagneaux
Bordet Institute, BRUSSELS, Belgium
Background. Chronic Lymphocytic Leukemia (CLL) is a heterogeneous
disease characterized by a highly variable clinical course based on the
IgVH mutational status currently considered as one of the powerful prognosis
factors. Because of the complexity of this analysis, several surrogate
genes of this mutational status have been found in the recent years,
among them Zap-70 seems to be a reliable prognostic factor. Methods.
We compared three predictive markers (Zap-70, lipoprotein lipase and
CD38 expression) in term of treatment-free (TFS) and overall (OS) survival
and finally Zap-70 (zeta-associated protein 70) was chosen because
of its strong association with the IgVH status and high prognostic values.
We developed a quantitative real time PCR to measure Zap-70
mRNA expression in a cohort of 100 patients and to classify patients
with high and low Zap-70 expression. Gene expression profiles of high
(Zap-70high , n=7) and low (Zap-70low , n=7) mRNA expression were then
compared using Affymetrix U133 plus 2.0 genechips representing more
than 47000 transcripts. Results. Among genes differently expressed
(p