Konference: 2006 48th ASH Annual Meeting - účast ČR
Kategorie: Maligní lymfomy a leukémie
Téma: Publikace ve sborníku
Číslo abstraktu: 4931
Autoři: Mgr. Jitka Chumchalová, Ph.D.; Dana Klimešová; Ing. Viera Kuhrová; Mgr. Hana Skuhrová Francová; MUDr. Yvona Brychtová, Ph.D.; prof. MUDr. Michael Doubek, Ph.D.; Ing. Dana Dvořáková, CSc.; prof. MUDr. Jiří Mayer, CSc.
Background: Chronic lymphocytic leukemia
(CLL) is the most common form of adult leukemia in the world. CLL
is currently an incurable disease, characterized by the gradual
accumulation of mature B-lymphocytes arrested in the G0 phase of
the cell cycle. STAT (signal transducers and activators of
transcription) proteins are involved in normal cellular events,
such as differentiation, proliferation, cell survival, apoptosis
and hematopoiesis. STAT proteins are constitutively activated in
hematopoetic cells transformed by oncogenic tyrosine kinases and
also in a variety of leukemias and lymphomas. The tyrosine
phosphorylation of the STATs allows formation of dimmers,
translocation to the nucleus and bindind of specific DNA sequences
in the promoters of target genes, leading to activation of
transcription. Serine phosphorylation is not sufficient to activate
the STAT, providing a degree of modulation of the gene activation
induced by the tyrosine phosphorylation. Serine phosphorylation of
STAT1 and STAT3 has been described in untreated B-CLL cells, but no
constitutive tyrosine phosphorylation has been detected in B-CLL
cells. Aims: Aim of our study was to examine defects in STAT1 and
STAT3 pathways in our CLL patients.
Methods: We analyzed defects in STAT1 and STAT3 pathways after stimulation of cells with 10 ng/ml IFNgama and 5000 IU/ml IFNalfa in 42 primary cultures derived from CLL patients. STAT1 and STAT3 inducibilities of their activated phospho-isoforms were detected by Western-blotting analysis using specific polyclonal and monoclonal antibodies.
Results: Constitutive phosphorylation of STAT1 and STAT3 proteins was detected in majority of patients (STAT1 PS727 95.2%, STAT3 PS727 90,6 %, STAT1 PY701 85,7% and STAT3 PY705 79,4%). The IFNalfa was shown to be a more effective inductor in comparison with IFNgama. The inducibility after IFNalfa with constitutive activation of both STAT proteins on serine and tyrosine was the most frequently detected. Inducibility after IFNalfa with constitutive activation at STAT1 PY701 was found in 61,9 % of samples, with 21,4% having the inducibility after both IFNs. Inducibility after IFNalfa at STAT3 PY705 was detected in 88,2% of cases, with 70,6% having a constitutive activation and 20,5% having not. Inducibility after IFNalfa with constitutive activation at both serine residues is the most commonly observed pattern (STAT1 PS727 40.5%, STAT3 PS727 70,6 %). A high proportion of patients had constitutive activation with no inducibility at serine (STAT1 PS727 47,6%, STAT3 PS727 28,1 %) compared to that at tyrozine (STAT1 PY701 19%, STAT3 PY705 2,9). The inducibility after IFN did not exceed 10 % in all cases.
Conclusions: Our results show constitutive phosphorylation of STAT1 and STAT3 proteins on both serine and tyrosine residues in most of our CLL patients. More effective inductor is the IFNalfa. Approximately a half of patients have defect of inducibility in serine phosphorylation of STAT1 protein.
Supported by grant NR8443-3/2005 provided by IGA of the Ministry of Health of the Czech Republic. E-mail: jitusak@sci.muni.cz.
Methods: We analyzed defects in STAT1 and STAT3 pathways after stimulation of cells with 10 ng/ml IFNgama and 5000 IU/ml IFNalfa in 42 primary cultures derived from CLL patients. STAT1 and STAT3 inducibilities of their activated phospho-isoforms were detected by Western-blotting analysis using specific polyclonal and monoclonal antibodies.
Results: Constitutive phosphorylation of STAT1 and STAT3 proteins was detected in majority of patients (STAT1 PS727 95.2%, STAT3 PS727 90,6 %, STAT1 PY701 85,7% and STAT3 PY705 79,4%). The IFNalfa was shown to be a more effective inductor in comparison with IFNgama. The inducibility after IFNalfa with constitutive activation of both STAT proteins on serine and tyrosine was the most frequently detected. Inducibility after IFNalfa with constitutive activation at STAT1 PY701 was found in 61,9 % of samples, with 21,4% having the inducibility after both IFNs. Inducibility after IFNalfa at STAT3 PY705 was detected in 88,2% of cases, with 70,6% having a constitutive activation and 20,5% having not. Inducibility after IFNalfa with constitutive activation at both serine residues is the most commonly observed pattern (STAT1 PS727 40.5%, STAT3 PS727 70,6 %). A high proportion of patients had constitutive activation with no inducibility at serine (STAT1 PS727 47,6%, STAT3 PS727 28,1 %) compared to that at tyrozine (STAT1 PY701 19%, STAT3 PY705 2,9). The inducibility after IFN did not exceed 10 % in all cases.
Conclusions: Our results show constitutive phosphorylation of STAT1 and STAT3 proteins on both serine and tyrosine residues in most of our CLL patients. More effective inductor is the IFNalfa. Approximately a half of patients have defect of inducibility in serine phosphorylation of STAT1 protein.
Supported by grant NR8443-3/2005 provided by IGA of the Ministry of Health of the Czech Republic. E-mail: jitusak@sci.muni.cz.
Datum přednesení příspěvku: 11. 12. 2006
