INHIBITION OF CXCR4 BY THE HIGH AFFINITY ANTAGONIST BL-8040 IN AML DOWNREGULATES BCL-2 THROUGH REGULATION OF MIR-15A/16-1 EXPRESSION
(Abstract release date: 05/19/16)
EHA Library. Abraham M. 06/09/16; 132430; E881
Dr. Michal Abraham
Contributions
Contributions
Abstract
Abstract: E881
Type: Eposter Presentation
Background
Acute Myeloid Leukemia (AML) is a heterogeneous group of diseases characterized by uncontrolled proliferation and survival of hematopoietic stem and progenitor cells. The chemokine CXCL12 and its receptor CXCR4 are key players in the retention of AML blasts in the protective bone marrow (BM) microenvironment. The CXCL12/CXCR4 axis is also critical for the survival and maintenance of AML blasts in their stemness state. CXCR4 overexpression is associated with poor prognosis in AML patients. Signaling activated through CXCR4 was shown to be detrimental by increasing survival of tumor cells and promoting resistance to therapy.
Aims
We have studied the effect of the CXCR4-antagonist, BL-8040 on the survival of human AML blasts and investigated the molecular mechanism by which inhibition of CXCR4 signaling leads to leukemia cell death.
Methods
Human AML cell line and human primary AML samples were used for in vitro studies. The in-vivo effect of BL-8040 was tested using MV4-11, U-937, THP-1 and human primary AML cells engrafted in NOD scid gamma (NSG) mice.
Results
We found that the human AML cells MV4-11, THP-1, U-937, and human primary AML cells express high levels of CXCR4. The CXCR4 antagonist, BL-8040 was found to induce apoptosis of the tested AML cells in-vitro and in-vivo. Survival of tested AML cells was found to be dependent on BCL-2 as demonstrated by the ability of the BCL-2 inhibitor, ABT-199 to induce dose dependent apoptosis in vitro. Interestingly, treatment of AML cells with BL-8040 reduced the expression of BCL-2 together with inhibition of the ERK signaling pathway. BL-8040 dependent reduction in BCL-2 expression was associated with increased expression of miR-15a/16-1. In addition to BCL-2, increased expression of miR-15a/16-1 reduced the expression of MCL-1 and cyclin D, its other target genes. Interestingly, these effects were not observed following stimulation with the CXCR4 antagonist, AMD3100. In support of these results overexpression of miR-15a/16-1 in AML cells was shown to induce their apoptosis.In the MV4-11 in-vivo AML model, when BL-8040 was administrated for 7 constitutive days we observed decreased number of AML cells accompanied with apoptosis in BM, Spleen and blood. Following one or two injections of BL-8040 apoptosis of AML blasts was observed together with upregulation of miR-15a/16-1 and decrease of BCL-2, only in the spleen. Importantly, Human AML cells engrafted to the spleen expressed lower levels of BCL-2 as compared to AML cells in the BM suggesting that the BM required prolonged inhibition in order to overcome the high levels of BCL-2 in this microenvironment.
Conclusion
Our results demonstrate that CXCR4 signaling regulates the expression of miR-15a/16-1 and their target genes BCL-2, MCL-1 and cyclin-D1. Furthermore, these results indicate that the CXCR4 antagonist, BL-8040 may tip the balance toward cell death by down- regulating survival signals through miR-15a/16-1 pathway and inhibition of the ERK signaling cascade in AML cells.
Session topic: E-poster
Keyword(s): AML, BCL2, CXCR4
Type: Eposter Presentation
Background
Acute Myeloid Leukemia (AML) is a heterogeneous group of diseases characterized by uncontrolled proliferation and survival of hematopoietic stem and progenitor cells. The chemokine CXCL12 and its receptor CXCR4 are key players in the retention of AML blasts in the protective bone marrow (BM) microenvironment. The CXCL12/CXCR4 axis is also critical for the survival and maintenance of AML blasts in their stemness state. CXCR4 overexpression is associated with poor prognosis in AML patients. Signaling activated through CXCR4 was shown to be detrimental by increasing survival of tumor cells and promoting resistance to therapy.
Aims
We have studied the effect of the CXCR4-antagonist, BL-8040 on the survival of human AML blasts and investigated the molecular mechanism by which inhibition of CXCR4 signaling leads to leukemia cell death.
Methods
Human AML cell line and human primary AML samples were used for in vitro studies. The in-vivo effect of BL-8040 was tested using MV4-11, U-937, THP-1 and human primary AML cells engrafted in NOD scid gamma (NSG) mice.
Results
We found that the human AML cells MV4-11, THP-1, U-937, and human primary AML cells express high levels of CXCR4. The CXCR4 antagonist, BL-8040 was found to induce apoptosis of the tested AML cells in-vitro and in-vivo. Survival of tested AML cells was found to be dependent on BCL-2 as demonstrated by the ability of the BCL-2 inhibitor, ABT-199 to induce dose dependent apoptosis in vitro. Interestingly, treatment of AML cells with BL-8040 reduced the expression of BCL-2 together with inhibition of the ERK signaling pathway. BL-8040 dependent reduction in BCL-2 expression was associated with increased expression of miR-15a/16-1. In addition to BCL-2, increased expression of miR-15a/16-1 reduced the expression of MCL-1 and cyclin D, its other target genes. Interestingly, these effects were not observed following stimulation with the CXCR4 antagonist, AMD3100. In support of these results overexpression of miR-15a/16-1 in AML cells was shown to induce their apoptosis.In the MV4-11 in-vivo AML model, when BL-8040 was administrated for 7 constitutive days we observed decreased number of AML cells accompanied with apoptosis in BM, Spleen and blood. Following one or two injections of BL-8040 apoptosis of AML blasts was observed together with upregulation of miR-15a/16-1 and decrease of BCL-2, only in the spleen. Importantly, Human AML cells engrafted to the spleen expressed lower levels of BCL-2 as compared to AML cells in the BM suggesting that the BM required prolonged inhibition in order to overcome the high levels of BCL-2 in this microenvironment.
Conclusion
Our results demonstrate that CXCR4 signaling regulates the expression of miR-15a/16-1 and their target genes BCL-2, MCL-1 and cyclin-D1. Furthermore, these results indicate that the CXCR4 antagonist, BL-8040 may tip the balance toward cell death by down- regulating survival signals through miR-15a/16-1 pathway and inhibition of the ERK signaling cascade in AML cells.
Session topic: E-poster
Keyword(s): AML, BCL2, CXCR4
Abstract: E881
Type: Eposter Presentation
Background
Acute Myeloid Leukemia (AML) is a heterogeneous group of diseases characterized by uncontrolled proliferation and survival of hematopoietic stem and progenitor cells. The chemokine CXCL12 and its receptor CXCR4 are key players in the retention of AML blasts in the protective bone marrow (BM) microenvironment. The CXCL12/CXCR4 axis is also critical for the survival and maintenance of AML blasts in their stemness state. CXCR4 overexpression is associated with poor prognosis in AML patients. Signaling activated through CXCR4 was shown to be detrimental by increasing survival of tumor cells and promoting resistance to therapy.
Aims
We have studied the effect of the CXCR4-antagonist, BL-8040 on the survival of human AML blasts and investigated the molecular mechanism by which inhibition of CXCR4 signaling leads to leukemia cell death.
Methods
Human AML cell line and human primary AML samples were used for in vitro studies. The in-vivo effect of BL-8040 was tested using MV4-11, U-937, THP-1 and human primary AML cells engrafted in NOD scid gamma (NSG) mice.
Results
We found that the human AML cells MV4-11, THP-1, U-937, and human primary AML cells express high levels of CXCR4. The CXCR4 antagonist, BL-8040 was found to induce apoptosis of the tested AML cells in-vitro and in-vivo. Survival of tested AML cells was found to be dependent on BCL-2 as demonstrated by the ability of the BCL-2 inhibitor, ABT-199 to induce dose dependent apoptosis in vitro. Interestingly, treatment of AML cells with BL-8040 reduced the expression of BCL-2 together with inhibition of the ERK signaling pathway. BL-8040 dependent reduction in BCL-2 expression was associated with increased expression of miR-15a/16-1. In addition to BCL-2, increased expression of miR-15a/16-1 reduced the expression of MCL-1 and cyclin D, its other target genes. Interestingly, these effects were not observed following stimulation with the CXCR4 antagonist, AMD3100. In support of these results overexpression of miR-15a/16-1 in AML cells was shown to induce their apoptosis.In the MV4-11 in-vivo AML model, when BL-8040 was administrated for 7 constitutive days we observed decreased number of AML cells accompanied with apoptosis in BM, Spleen and blood. Following one or two injections of BL-8040 apoptosis of AML blasts was observed together with upregulation of miR-15a/16-1 and decrease of BCL-2, only in the spleen. Importantly, Human AML cells engrafted to the spleen expressed lower levels of BCL-2 as compared to AML cells in the BM suggesting that the BM required prolonged inhibition in order to overcome the high levels of BCL-2 in this microenvironment.
Conclusion
Our results demonstrate that CXCR4 signaling regulates the expression of miR-15a/16-1 and their target genes BCL-2, MCL-1 and cyclin-D1. Furthermore, these results indicate that the CXCR4 antagonist, BL-8040 may tip the balance toward cell death by down- regulating survival signals through miR-15a/16-1 pathway and inhibition of the ERK signaling cascade in AML cells.
Session topic: E-poster
Keyword(s): AML, BCL2, CXCR4
Type: Eposter Presentation
Background
Acute Myeloid Leukemia (AML) is a heterogeneous group of diseases characterized by uncontrolled proliferation and survival of hematopoietic stem and progenitor cells. The chemokine CXCL12 and its receptor CXCR4 are key players in the retention of AML blasts in the protective bone marrow (BM) microenvironment. The CXCL12/CXCR4 axis is also critical for the survival and maintenance of AML blasts in their stemness state. CXCR4 overexpression is associated with poor prognosis in AML patients. Signaling activated through CXCR4 was shown to be detrimental by increasing survival of tumor cells and promoting resistance to therapy.
Aims
We have studied the effect of the CXCR4-antagonist, BL-8040 on the survival of human AML blasts and investigated the molecular mechanism by which inhibition of CXCR4 signaling leads to leukemia cell death.
Methods
Human AML cell line and human primary AML samples were used for in vitro studies. The in-vivo effect of BL-8040 was tested using MV4-11, U-937, THP-1 and human primary AML cells engrafted in NOD scid gamma (NSG) mice.
Results
We found that the human AML cells MV4-11, THP-1, U-937, and human primary AML cells express high levels of CXCR4. The CXCR4 antagonist, BL-8040 was found to induce apoptosis of the tested AML cells in-vitro and in-vivo. Survival of tested AML cells was found to be dependent on BCL-2 as demonstrated by the ability of the BCL-2 inhibitor, ABT-199 to induce dose dependent apoptosis in vitro. Interestingly, treatment of AML cells with BL-8040 reduced the expression of BCL-2 together with inhibition of the ERK signaling pathway. BL-8040 dependent reduction in BCL-2 expression was associated with increased expression of miR-15a/16-1. In addition to BCL-2, increased expression of miR-15a/16-1 reduced the expression of MCL-1 and cyclin D, its other target genes. Interestingly, these effects were not observed following stimulation with the CXCR4 antagonist, AMD3100. In support of these results overexpression of miR-15a/16-1 in AML cells was shown to induce their apoptosis.In the MV4-11 in-vivo AML model, when BL-8040 was administrated for 7 constitutive days we observed decreased number of AML cells accompanied with apoptosis in BM, Spleen and blood. Following one or two injections of BL-8040 apoptosis of AML blasts was observed together with upregulation of miR-15a/16-1 and decrease of BCL-2, only in the spleen. Importantly, Human AML cells engrafted to the spleen expressed lower levels of BCL-2 as compared to AML cells in the BM suggesting that the BM required prolonged inhibition in order to overcome the high levels of BCL-2 in this microenvironment.
Conclusion
Our results demonstrate that CXCR4 signaling regulates the expression of miR-15a/16-1 and their target genes BCL-2, MCL-1 and cyclin-D1. Furthermore, these results indicate that the CXCR4 antagonist, BL-8040 may tip the balance toward cell death by down- regulating survival signals through miR-15a/16-1 pathway and inhibition of the ERK signaling cascade in AML cells.
Session topic: E-poster
Keyword(s): AML, BCL2, CXCR4
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