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ZAP-70 Tyrosine Kinase Is Constitutively Expressed and Phosphorylated in B-lineage Acute Lymphoblastic Leukemia Cells

ZAP-70 Tyrosine Kinase Is Constitutively Expressed and Phosphorylated in B-lineage Acute Lymphoblastic Leukemia Cells

Nicolas Guillaume, Céline Alleaume, Délicia Munfus, Jean-Claude Capiod, Gilles Touati, Brigitte Pautard, Bernard Desablens, Jean-Jacques Lefrère, Fabrice Gouilleux, Kaiss Lassoued, Valérie Gouilleux-Gruart

Haematologica. 2005 Jul;90(7):899-905.

PMID: 15996927

Abstract:

Background and objectives:
Zeta-associated protein 70 (ZAP-70), a member of the Syk family of protein tyrosine kinases, is normally expressed in T and NK cells. While little is known about ZAP-70 expression in normal human B cells, it has been reported that ZAP-70 is expressed in a subset of patients with chronic lymphocytic leukemia (CLL) with a poor prognosis. In this study, we examined the expression and phosphorylation status of ZAP-70 in B-lineage acute lymphoblastic leukemia (Blin-ALL).
Design and methods:
First, ZAP-70 protein expression was assessed by Western blotting and flow cytometry and ZAP-70 mRNA transcripts were analyzed by reverse transcription polymerase chain reaction (RT-PCR) on human precursor B cell lines. Experiments were then carried out on cells obtained from 18 patients with Blin-ALL and from normal human bone marrow.
Results:
ZAP-70 was constitutively expressed and phosphorylated on tyr319 in human precursor Blin-ALL cell lines as well as in primary B leukemic cells from all examined Blin-ALL patients with pro-B, pre-B and B phenotypes, but not in malignant myeloid cells. Importantly, analysis of normal human bone marrow revealed expression of ZAP-70 transcripts only in the CD34+ cell fraction (either CD19-CD10- or CD19+CD10+) but not in the CD34- cell fraction (CD19+sIgM- pre-B cells or CD19+sIgM+ immature B cells).
Interpretation and conclusions:
ZAP-70 was found to be expressed in the CD34+ normal bone marrow compartment including earlier B-cell progenitors, but not in CD34- pre-B and immature B cells. By contrast, ZAP-70 was consistently expressed and phosphorylated in Blin-ALL cells. Further studies are required to determine whether ZAP-70 may play a pathophysiological role in Blin-ALL.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
IAR42411991	ZAP-70 Tyrosine Kinase human			Price

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