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Spi-1 transgenic mice develop a clonal erythroleukemia which does not depend on p53 mutation
S Barnache1, F Wendling, C Lacombe
1INSERM U248, Institut Curie, Paris, France.
Oncogene
|July 14, 1998
Summary
Spi-1 overexpression blocks erythroblast differentiation independently of p53. However, Friend acute erythroleukemia development involves two steps, with p53 alterations cooperating with Spi-1 in later stages.
Area of Science:
- Oncology
- Molecular Biology
- Hematology
Background:
- Friend acute erythroleukemia involves Spi-1 activation and p53 inactivation.
- Understanding the roles of Spi-1 and p53 in erythroblast transformation is crucial.
Purpose of the Study:
- To investigate the contribution of Spi-1 and p53 alterations in erythroblast differentiation and proliferation deregulation.
- To dissect the stepwise development of erythroleukemia in spi-1 transgenic mice.
Main Methods:
- Generation of spi-1 transgenic mice.
- Analysis of proerythroblast differentiation, proliferation, and tumorigenicity.
- Provirus tagging to identify clonal evolution.
- p53 mutation analysis in primary tissues and cell lines.
Main Results:
- Spi-1 overexpression blocks proerythroblast differentiation independently of p53.
- Erythroleukemia develops in two steps: an early erythropoietin-dependent phase (HS1) and a later erythropoietin-independent, tumorigenic phase (HS2).
- p53 mutations were observed in cultured HS1 cells and in HS2 primary tissues, but not required for erythropoietin independence.
Conclusions:
- Spi-1 overexpression is sufficient to block erythroblast differentiation.
- p53 alterations are not necessary for initiating erythropoietin independence or tumorigenicity in spi-1 transgenic erythroblasts.
- Cooperation between Spi-1 and other oncogenes, potentially including mutated p53, drives the progression to fully malignant erythroleukemia.