Related Experiment Video
Updated: Jul 24, 2026
Flow Cytometry to Estimate Leukemia Stem Cells in Primary Acute Myeloid Leukemia and in Patient-derived-xenografts, at Diagnosis and Follow Up
Published on: March 26, 2018
Functional G-CSF pathways in t(8;21) leukemic cells allow for differentiation induction and degradation of AML1-ETO
N Da Silva1, S Meyer-Monard, M L Menot
1Laboratoire de Biologie Cellulaire Hématopoïétique (LBCH), INSERM E 00-03, et EA 316 Université Paris 7, Hôpital Saint-Louis, 1 Avenue Claude Vellefaux, 75754 Paris Cedex 10, France. lbch@chu.stlouis.fr
Introduction:
Efficacy of differentiating agents requires that their specific cellular targets are still expressed and functional in the leukemic cells. One hypothesis to target sensitive cells is to select leukemic clones which harbor disrupted transcription factors. CBFalpha and CBFbeta are core-binding proteins which have been identified as transcription regulators of hematopoietic genes and shown to be altered in numerous leukemias. In M2 AML, the t(8;21) translocation, CBFalpha (AML1) is altered and produced as the AML1-ETO fusion protein. The fusion protein blocks transcription and differentiation mediated by G-CSF. Interestingly, AML1-ETO leukemic cell lines are sensitive to numerous cytokines in vitro and can be induced to differentiate in the presence of G-CSF and PMA.
Materials And Methods:
As in the APL differentiation model, primary culture provides a useful tool for therapeutic screening of differentiation inducers, we analysed the in vitro sensitivity of 10 fresh M2 AML t(8;21) leukemic samples to G-CSF and the functionality of G-CSF intracellular pathways. In vitro data were compared with in vivo data from four patients treated with rhG-CSF at the dosage of 5 microg/kg/day i.v. for two to three weeks before the initiation of AML induction chemotherapy and immunophenotypic analysis performed weekly to monitor in vivo differentiation.
Results:
In vitro, an increase in CD34+ cells expressing differentiation antigens (CD11b, CD13 or CD15) was noted along with a decrease of immature CD34+/differentiation antigen negative cells. After two weeks of a daily rhG-CSF administration in vivo, a significant, albeit transient, decrease of blast count was achieved, concomitant with an increase in differentiated leukemic cells suggesting that in vivo differentiation occurs. Fresh t(8;21) leukemic cells possess functional G-CSF signaling pathways as normal activity and kinetics of STAT1 and STAT3 binding was observed. Furthermore, differentiation induction leads to a subsequent degradation of the AML1-ETO oncoprotein.
Conclusion:
The data presented here supports the claim that G-CSF can induce in vitro and in vivo differentiation of M2 AML t(8;21) cells.
Insights
Granulocyte-colony stimulating factor (G-CSF) effectively induces differentiation in M2 acute myeloid leukemia (AML) cells with the t(8;21) translocation, both in vitro and in vivo. This G-CSF treatment also leads to the degradation of the AML1-ETO oncoprotein.
Area of Science:
- Hematology
- Molecular Biology
- Oncology
Background:
- Efficacy of differentiation therapy in leukemia depends on target gene expression in leukemic cells.
- Altered transcription factors, such as CBFalpha (AML1) in M2 AML with t(8;21) translocation, can lead to the AML1-ETO fusion protein, inhibiting differentiation.
- AML1-ETO leukemic cell lines show sensitivity to cytokines like G-CSF and PMA for differentiation induction.
Purpose of the Study:
- To investigate the in vitro and in vivo sensitivity of M2 AML t(8;21) cells to G-CSF.
- To analyze the functionality of G-CSF intracellular pathways in these leukemic cells.
- To compare in vitro differentiation responses with in vivo outcomes in patients treated with rhG-CSF.
Main Methods:
- Primary culture of 10 fresh M2 AML t(8;21) leukemic samples for in vitro G-CSF sensitivity testing.
- Analysis of G-CSF intracellular pathway functionality (STAT1 and STAT3 binding).
- In vivo study of 4 patients treated with rhG-CSF before chemotherapy, with weekly immunophenotypic analysis.
Main Results:
- In vitro, G-CSF increased differentiation antigens on CD34+ cells and decreased immature cells.
- In vivo, rhG-CSF administration resulted in a transient decrease in blast count and an increase in differentiated leukemic cells.
- Functional G-CSF signaling pathways (STAT1/STAT3 binding) were observed, and differentiation induction led to AML1-ETO oncoprotein degradation.
Conclusions:
- G-CSF demonstrates the ability to induce differentiation in M2 AML t(8;21) cells both in vitro and in vivo.
- The findings support G-CSF as a potential therapeutic agent for this specific subtype of AML.
- Functional G-CSF signaling and subsequent oncoprotein degradation highlight a mechanism for therapeutic intervention.
