Max
07-15-2002, 04:55 PM
Hypoxia Modifies Proliferation and Differentiation of CD34+ CML Cells
Vanessa Desplata, Jean-Luc Faucherb, François Xavier Mahona, Persio Dello Sbarbac, Vincent Pralorand, Zoran Ivanovicd
a Laboratoire de Greffe de Moelle, Université Bordeaux 2, Bordeaux, France;
b Laboratoire d'Hématologie, CHU de Limoges, Limoges, France;
c Dipartimento di Patologia e Oncologia Sperimentali, Universita di Firenze, Firenze, Italia;
d Laboratoire Universitaire d'Hématologie, Université Bordeaux 2, Bordeaux, France
Key Words: Hypoxia· CML cells· CD34+ cells· Differentiation· PAF-R
Correspondence: Zoran Ivanovic, Ph.D., Laboratoire Universitaire d'Hématologie, 146 rue Léo Saignat, 33076 Bordeaux cedex, France. Telephone: 33-05-5757-1611; Fax: 33-05-5651-4218; e-mail: Zoran.Ivanovic@hemato.u-bordeaux2.fr
We previously showed that hypoxia (1% O2) favors the self-renewal of murine and human normal hematopoietic stem cells. This study represents the first attempt to characterize the effects of hypoxia on the maintenance of chronic myeloid leukemia (CML) progenitors. CD34+ cells isolated from apheresis products of CML patients were incubated in hypoxia (1% O2) and normoxia (20% O2). After 8 days of culture, their proliferation, capacity for colony-forming-cell (CFC) generation in secondary cultures (pre-CFC), and phenotype (CD34 and platelet-activating factor receptor [PAF-R]) were compared with those of normal cells, and tyrosine phosphorylation in CML cells was measured. Hypoxia inhibits the proliferation of CD34+ cells and preserves the pre-CFC capacity and cell-surface CD34 expression of CML cells better than normoxia. The PAF-R expression, which was absent on freshly isolated cells, was detected at the cell surface in both populations after 8 days of culture, but with a lower percentage of positive cells in CML cell cultures. Incubation in hypoxia suppressed the PAF-R expression of normal cells and increased it in CML cells, resulting in a similar expression in the two populations. These effects could be linked to inhibition by hypoxia of the tyrosine hyperphosphorylation of cellular proteins, a major hallmark of CML cells.
Vanessa Desplata, Jean-Luc Faucherb, François Xavier Mahona, Persio Dello Sbarbac, Vincent Pralorand, Zoran Ivanovicd
a Laboratoire de Greffe de Moelle, Université Bordeaux 2, Bordeaux, France;
b Laboratoire d'Hématologie, CHU de Limoges, Limoges, France;
c Dipartimento di Patologia e Oncologia Sperimentali, Universita di Firenze, Firenze, Italia;
d Laboratoire Universitaire d'Hématologie, Université Bordeaux 2, Bordeaux, France
Key Words: Hypoxia· CML cells· CD34+ cells· Differentiation· PAF-R
Correspondence: Zoran Ivanovic, Ph.D., Laboratoire Universitaire d'Hématologie, 146 rue Léo Saignat, 33076 Bordeaux cedex, France. Telephone: 33-05-5757-1611; Fax: 33-05-5651-4218; e-mail: Zoran.Ivanovic@hemato.u-bordeaux2.fr
We previously showed that hypoxia (1% O2) favors the self-renewal of murine and human normal hematopoietic stem cells. This study represents the first attempt to characterize the effects of hypoxia on the maintenance of chronic myeloid leukemia (CML) progenitors. CD34+ cells isolated from apheresis products of CML patients were incubated in hypoxia (1% O2) and normoxia (20% O2). After 8 days of culture, their proliferation, capacity for colony-forming-cell (CFC) generation in secondary cultures (pre-CFC), and phenotype (CD34 and platelet-activating factor receptor [PAF-R]) were compared with those of normal cells, and tyrosine phosphorylation in CML cells was measured. Hypoxia inhibits the proliferation of CD34+ cells and preserves the pre-CFC capacity and cell-surface CD34 expression of CML cells better than normoxia. The PAF-R expression, which was absent on freshly isolated cells, was detected at the cell surface in both populations after 8 days of culture, but with a lower percentage of positive cells in CML cell cultures. Incubation in hypoxia suppressed the PAF-R expression of normal cells and increased it in CML cells, resulting in a similar expression in the two populations. These effects could be linked to inhibition by hypoxia of the tyrosine hyperphosphorylation of cellular proteins, a major hallmark of CML cells.