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Elevated levels of basic fibroblast growth factor in megakaryocytes and platelets from patients with idiopathic
M C Martyré1, M C Le Bousse-Kerdiles, N Romquin
1Unité 365 INSERM, Institut Curie, Section de Recherche, Paris, France.
Abstract:
Idiopathic myelofibrosis, or agnogenic myeloid metaplasia, is a chronic myeloproliferative disorder characterized by clonal expansion and marrow fibrosis. Although marrow fibrosis appears to be a reactive process, it substantially contributes to impaired haemopoiesis. During the last few years the implication of megakaryocyte-derived growth factors in its pathogenesis has been documented. We previously reported increased expression of TGF-beta in patients with idiopathic myelofibrosis. In the present study we show that circulating megakaryocytic cells from such patients expressed high levels of basic fibroblast growth factor (bFGF). An increased expression of bFGF was also detected in patients' platelets. Under culture conditions, bFGF present in megakaryocytic cells was not exported into the medium. consistent with the fact that bFGF is devoid of a secretion peptide signal. Interestingly, this lack of bFGF secretion was observed in all patients but one, who was in an accelerated phase of the disease and presented an important percentage of circulating megakaryoblasts.
Insights
Idiopathic myelofibrosis involves marrow fibrosis and impaired blood cell production. This study found increased basic fibroblast growth factor (bFGF) in circulating cells and platelets of patients, suggesting its role in the disease.
Area of Science:
- Hematology
- Oncology
- Molecular Biology
Background:
- Idiopathic myelofibrosis is a chronic myeloproliferative disorder.
- Marrow fibrosis impairs blood cell production (hemopoiesis).
- Megakaryocyte-derived growth factors are implicated in its pathogenesis.
Purpose of the Study:
- To investigate the role of basic fibroblast growth factor (bFGF) in idiopathic myelofibrosis.
- To examine bFGF expression in circulating cells and platelets of patients.
Main Methods:
- Analysis of circulating megakaryocytic cells and platelets from patients.
- Assessment of bFGF expression levels.
- Evaluation of bFGF secretion under culture conditions.
Main Results:
- Patients with idiopathic myelofibrosis showed high levels of bFGF in circulating megakaryocytic cells.
- Increased bFGF expression was also found in patients' platelets.
- bFGF was not secreted into the medium from megakaryocytic cells, except in one patient with accelerated disease.
Conclusions:
- Elevated bFGF in circulating cells and platelets may contribute to idiopathic myelofibrosis pathogenesis.
- The lack of bFGF secretion suggests intracellular mechanisms may be involved.
- Further research is needed to clarify the specific role of bFGF in this condition.