AGONISTIC TARGETING OF TLR1/TLR2 FORCES ACUTE MYELOID LEUKEMIA CELLS INTO DIFFERENTIATION
(Abstract release date: 05/19/16)
EHA Library. Eriksson M. 06/12/16; 135299; S805
Ms. Mia Eriksson
Contributions
Contributions
Abstract
Abstract: S805
Type: Oral Presentation
Presentation during EHA21: On Sunday, June 12, 2016 from 08:30 - 08:45
Location: Hall A3
Background
Acute myeloid leukemia (AML) is a fatal disease that is characterized by a rapid expansion of myeloid leukemic blasts with impaired differentiation that accumulate in the bone marrow. Because the prognosis for AML is poor and the treatment for most AML subgroups has remained similar for almost four decades, demand is strong for new types of therapies in this disorder. It is thought that one of the major obstacles in successfully treating AML is to efficiently target the AML cells with leukemia-initiating capacity, which often evade standard chemotherapy treatments, leading to disease relapse.
Aims
The aim of this project has been to characterize Toll-like receptor 1 (TLR1) as a therapeutic target on primitive AML cells.
Methods
A murine AML model driven by retroviral MLL-AF9 fusion expression was used for the mouse studies. Flow cytometry was used to measure Tlr1 expression, for cell cycle analysis, and to measure activated AKT and NFκB. For studies of human AML, MLL-AF9 transformed cord blood cells were used, and also AML patient samples. Global gene expression profiling was performed using RNA-sequencing.
Results
In search for candidate therapeutic cell surface targets in AML, we here identified TLR1 as upregulated in primitive AML cells relative to corresponding normal bone marrow cells. Stimulating primitive leukemic cells with Pam3CSK4, a Tlr1/Tlr2 agonist, resulted in an increase in actively cycling cells and cell expansion. Morphologic analysis and enhanced CD11b expression indicated rapid myeloid differentiation of the cells. Moreover, Pam3CSK4 strongly suppressed their leukemia-initiating capacity as assessed in ex vivo treatment experiments followed by transplantations into sublethally irradiated recipient mice. In contrast, ex vivo Pam3CSK4-stimulation of normal hematopoietic stem and progenitor cells only mildly suppressed their long-term repopulating ability in competitive transplants. In human leukemia, Pam3CSK4-stimulation of MLL-AF9-transformed cord blood cells pushed them into differentiation and eradicated their colony-forming capacity accompanied by AKT and NFκB activation. In AML patient samples, Pam3CSK4 caused cell differentiation, evidenced by morphological changes consistent with macrophage outgrowth and an increase in CD15-expressing cells, whereas minor effects were observed in normal bone marrow cells. The Pam3CSK4-induced differentiation showed strong correlated (r=0.98) with the level of TLR1 expression in AML CD34+CD38- cells. Hence, our data suggest that AML patients with high TLR1 expression would be more susceptible to treatments targeting TLR1.
Conclusion
In summary, these findings demonstrate that TLR1 is upregulated in primitive AML cells and that agonistic targeting of the TLR1/TLR2 complex forces AML cells into differentiation, revealing a new putative strategy for therapeutically differentiating AML cells.
Session topic: AML Biology - Novel targeted therapies
Type: Oral Presentation
Presentation during EHA21: On Sunday, June 12, 2016 from 08:30 - 08:45
Location: Hall A3
Background
Acute myeloid leukemia (AML) is a fatal disease that is characterized by a rapid expansion of myeloid leukemic blasts with impaired differentiation that accumulate in the bone marrow. Because the prognosis for AML is poor and the treatment for most AML subgroups has remained similar for almost four decades, demand is strong for new types of therapies in this disorder. It is thought that one of the major obstacles in successfully treating AML is to efficiently target the AML cells with leukemia-initiating capacity, which often evade standard chemotherapy treatments, leading to disease relapse.
Aims
The aim of this project has been to characterize Toll-like receptor 1 (TLR1) as a therapeutic target on primitive AML cells.
Methods
A murine AML model driven by retroviral MLL-AF9 fusion expression was used for the mouse studies. Flow cytometry was used to measure Tlr1 expression, for cell cycle analysis, and to measure activated AKT and NFκB. For studies of human AML, MLL-AF9 transformed cord blood cells were used, and also AML patient samples. Global gene expression profiling was performed using RNA-sequencing.
Results
In search for candidate therapeutic cell surface targets in AML, we here identified TLR1 as upregulated in primitive AML cells relative to corresponding normal bone marrow cells. Stimulating primitive leukemic cells with Pam3CSK4, a Tlr1/Tlr2 agonist, resulted in an increase in actively cycling cells and cell expansion. Morphologic analysis and enhanced CD11b expression indicated rapid myeloid differentiation of the cells. Moreover, Pam3CSK4 strongly suppressed their leukemia-initiating capacity as assessed in ex vivo treatment experiments followed by transplantations into sublethally irradiated recipient mice. In contrast, ex vivo Pam3CSK4-stimulation of normal hematopoietic stem and progenitor cells only mildly suppressed their long-term repopulating ability in competitive transplants. In human leukemia, Pam3CSK4-stimulation of MLL-AF9-transformed cord blood cells pushed them into differentiation and eradicated their colony-forming capacity accompanied by AKT and NFκB activation. In AML patient samples, Pam3CSK4 caused cell differentiation, evidenced by morphological changes consistent with macrophage outgrowth and an increase in CD15-expressing cells, whereas minor effects were observed in normal bone marrow cells. The Pam3CSK4-induced differentiation showed strong correlated (r=0.98) with the level of TLR1 expression in AML CD34+CD38- cells. Hence, our data suggest that AML patients with high TLR1 expression would be more susceptible to treatments targeting TLR1.
Conclusion
In summary, these findings demonstrate that TLR1 is upregulated in primitive AML cells and that agonistic targeting of the TLR1/TLR2 complex forces AML cells into differentiation, revealing a new putative strategy for therapeutically differentiating AML cells.
Session topic: AML Biology - Novel targeted therapies
Abstract: S805
Type: Oral Presentation
Presentation during EHA21: On Sunday, June 12, 2016 from 08:30 - 08:45
Location: Hall A3
Background
Acute myeloid leukemia (AML) is a fatal disease that is characterized by a rapid expansion of myeloid leukemic blasts with impaired differentiation that accumulate in the bone marrow. Because the prognosis for AML is poor and the treatment for most AML subgroups has remained similar for almost four decades, demand is strong for new types of therapies in this disorder. It is thought that one of the major obstacles in successfully treating AML is to efficiently target the AML cells with leukemia-initiating capacity, which often evade standard chemotherapy treatments, leading to disease relapse.
Aims
The aim of this project has been to characterize Toll-like receptor 1 (TLR1) as a therapeutic target on primitive AML cells.
Methods
A murine AML model driven by retroviral MLL-AF9 fusion expression was used for the mouse studies. Flow cytometry was used to measure Tlr1 expression, for cell cycle analysis, and to measure activated AKT and NFκB. For studies of human AML, MLL-AF9 transformed cord blood cells were used, and also AML patient samples. Global gene expression profiling was performed using RNA-sequencing.
Results
In search for candidate therapeutic cell surface targets in AML, we here identified TLR1 as upregulated in primitive AML cells relative to corresponding normal bone marrow cells. Stimulating primitive leukemic cells with Pam3CSK4, a Tlr1/Tlr2 agonist, resulted in an increase in actively cycling cells and cell expansion. Morphologic analysis and enhanced CD11b expression indicated rapid myeloid differentiation of the cells. Moreover, Pam3CSK4 strongly suppressed their leukemia-initiating capacity as assessed in ex vivo treatment experiments followed by transplantations into sublethally irradiated recipient mice. In contrast, ex vivo Pam3CSK4-stimulation of normal hematopoietic stem and progenitor cells only mildly suppressed their long-term repopulating ability in competitive transplants. In human leukemia, Pam3CSK4-stimulation of MLL-AF9-transformed cord blood cells pushed them into differentiation and eradicated their colony-forming capacity accompanied by AKT and NFκB activation. In AML patient samples, Pam3CSK4 caused cell differentiation, evidenced by morphological changes consistent with macrophage outgrowth and an increase in CD15-expressing cells, whereas minor effects were observed in normal bone marrow cells. The Pam3CSK4-induced differentiation showed strong correlated (r=0.98) with the level of TLR1 expression in AML CD34+CD38- cells. Hence, our data suggest that AML patients with high TLR1 expression would be more susceptible to treatments targeting TLR1.
Conclusion
In summary, these findings demonstrate that TLR1 is upregulated in primitive AML cells and that agonistic targeting of the TLR1/TLR2 complex forces AML cells into differentiation, revealing a new putative strategy for therapeutically differentiating AML cells.
Session topic: AML Biology - Novel targeted therapies
Type: Oral Presentation
Presentation during EHA21: On Sunday, June 12, 2016 from 08:30 - 08:45
Location: Hall A3
Background
Acute myeloid leukemia (AML) is a fatal disease that is characterized by a rapid expansion of myeloid leukemic blasts with impaired differentiation that accumulate in the bone marrow. Because the prognosis for AML is poor and the treatment for most AML subgroups has remained similar for almost four decades, demand is strong for new types of therapies in this disorder. It is thought that one of the major obstacles in successfully treating AML is to efficiently target the AML cells with leukemia-initiating capacity, which often evade standard chemotherapy treatments, leading to disease relapse.
Aims
The aim of this project has been to characterize Toll-like receptor 1 (TLR1) as a therapeutic target on primitive AML cells.
Methods
A murine AML model driven by retroviral MLL-AF9 fusion expression was used for the mouse studies. Flow cytometry was used to measure Tlr1 expression, for cell cycle analysis, and to measure activated AKT and NFκB. For studies of human AML, MLL-AF9 transformed cord blood cells were used, and also AML patient samples. Global gene expression profiling was performed using RNA-sequencing.
Results
In search for candidate therapeutic cell surface targets in AML, we here identified TLR1 as upregulated in primitive AML cells relative to corresponding normal bone marrow cells. Stimulating primitive leukemic cells with Pam3CSK4, a Tlr1/Tlr2 agonist, resulted in an increase in actively cycling cells and cell expansion. Morphologic analysis and enhanced CD11b expression indicated rapid myeloid differentiation of the cells. Moreover, Pam3CSK4 strongly suppressed their leukemia-initiating capacity as assessed in ex vivo treatment experiments followed by transplantations into sublethally irradiated recipient mice. In contrast, ex vivo Pam3CSK4-stimulation of normal hematopoietic stem and progenitor cells only mildly suppressed their long-term repopulating ability in competitive transplants. In human leukemia, Pam3CSK4-stimulation of MLL-AF9-transformed cord blood cells pushed them into differentiation and eradicated their colony-forming capacity accompanied by AKT and NFκB activation. In AML patient samples, Pam3CSK4 caused cell differentiation, evidenced by morphological changes consistent with macrophage outgrowth and an increase in CD15-expressing cells, whereas minor effects were observed in normal bone marrow cells. The Pam3CSK4-induced differentiation showed strong correlated (r=0.98) with the level of TLR1 expression in AML CD34+CD38- cells. Hence, our data suggest that AML patients with high TLR1 expression would be more susceptible to treatments targeting TLR1.
Conclusion
In summary, these findings demonstrate that TLR1 is upregulated in primitive AML cells and that agonistic targeting of the TLR1/TLR2 complex forces AML cells into differentiation, revealing a new putative strategy for therapeutically differentiating AML cells.
Session topic: AML Biology - Novel targeted therapies
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