HIF-2? IS A TUMOUR SUPPRESSOR IN AML
(Abstract release date: 05/21/15)
EHA Library. Vukovic M. 06/12/15; 103055; S120
Disclosure(s): University of EdinburghMRC Centre for Regenerative Medicine
Milica Vukovic
Contributions
Contributions
Abstract
Abstract: S120
Type: Oral Presentation + travel grant
Presentation during EHA20: From 12.06.2015 12:30 to 12.06.2015 12:45
Location: Room C2
Background
Normal and malignant haematopoiesis occur under hypoxic conditions. Hif-1α and Hif-2α regulate gene expression to facilitate adaptation to low oxygen tension. Several studies investigated the role of Hif-1α and Hif-2α in acute myeloid leukaemia (AML). These studies used shRNA knockdown in human AML samples to show that HIF-1α and HIF-2α knockdown compromised the ability of AML samples to reconstitute AML upon transplantation into recipient mice, suggesting that HIF-1 and HIF-2 are potential therapeutic targets for AML. However, a recent study demonstrated that conditional genetic deletion of Hif-1α did not compromise the development and maintenance of mouse leukaemic stem cells (LSCs) and on the contrary, accelerated the development of AML, indicating that Hif-1α is a tumour suppressor in AML. To date, the effect of conditional deletion of Hif-2α has not been examined in AML.
Aims
To investigate the requirement of Hif-2α in the development and maintenance of AML leukaemic stem cells.
Methods
We generated Hif-2αfl/fl;Vav-iCre mice that lack Hif-2α specifically within the hematopoietic system. We retrovirally co-transduced BM c-Kit+ cells with oncogenes Meis1a and Hoxa9 and serially re-plated them to establish pre-leukaemic stem cells (pre-LSCs). Retrovirally transduced cells were subjected to in vitro assays in normoxia and hypoxia or transplanted into lethally irradiated primary recipients, and subsequently into secondary recipients. We next generated Mll-AF9KI/+; Hif-2αfl/fl;Vav-iCre mice and controls and transplanted Lin-Sca-1+c-Kit+(LSK) cells from these mice into primary recipients, and Lin-Sca-1-c-Kit+(LK) cells into secondary recipients.
Results
Hif-2α-deficient and control cells displayed similar re-plating capacity and generated comparable numbers of colonies, but had increased proliferative capacity. Thus, Hif-2α is not required for in vitro transformation and generation of pre-LSCs but suppresses their proliferation. Transplantation of pre-LSCs to primary recipients demonstrated that a smaller proportion of recipients of Hif-2α-deficient pre-LSCs remained leukaemia-free, and therefore succumbed to AML faster than recipients of control pre-LSCs. However, secondary recipients of both Hif-2α-deficient and control LSCs generated aggressive AML with similar latency. In concordance with these data, recipients of Mll-AF9KI/+; Hif-2αfl/fl;Vav-iCre succumbed to AML faster compared to recipients of control LSK cells, whereas, secondary recipients of both genotypes generated AML with similar latency.
Summary
Deletion of Hif-2α in pre-LSCs accelerates development of LSCs and shortens AML latency induced by Mll-AF9 and its downstream effectors Meis1 and Hoxa9. Surprisingly, established LSCs lacking Hif-2α efficiently propagate aggressive AML. We conclude that while Hif-2α suppresses the development of AML, it is not required for LSC maintenance. Therefore, HIF-2 is unlikely to be a broad therapeutic target in AML and the benefit of HIF inhibition should be carefully re-examined in all subsets of AML.
Session topic: Molecular pathogenesis of AML
Type: Oral Presentation + travel grant
Presentation during EHA20: From 12.06.2015 12:30 to 12.06.2015 12:45
Location: Room C2
Background
Normal and malignant haematopoiesis occur under hypoxic conditions. Hif-1α and Hif-2α regulate gene expression to facilitate adaptation to low oxygen tension. Several studies investigated the role of Hif-1α and Hif-2α in acute myeloid leukaemia (AML). These studies used shRNA knockdown in human AML samples to show that HIF-1α and HIF-2α knockdown compromised the ability of AML samples to reconstitute AML upon transplantation into recipient mice, suggesting that HIF-1 and HIF-2 are potential therapeutic targets for AML. However, a recent study demonstrated that conditional genetic deletion of Hif-1α did not compromise the development and maintenance of mouse leukaemic stem cells (LSCs) and on the contrary, accelerated the development of AML, indicating that Hif-1α is a tumour suppressor in AML. To date, the effect of conditional deletion of Hif-2α has not been examined in AML.
Aims
To investigate the requirement of Hif-2α in the development and maintenance of AML leukaemic stem cells.
Methods
We generated Hif-2αfl/fl;Vav-iCre mice that lack Hif-2α specifically within the hematopoietic system. We retrovirally co-transduced BM c-Kit+ cells with oncogenes Meis1a and Hoxa9 and serially re-plated them to establish pre-leukaemic stem cells (pre-LSCs). Retrovirally transduced cells were subjected to in vitro assays in normoxia and hypoxia or transplanted into lethally irradiated primary recipients, and subsequently into secondary recipients. We next generated Mll-AF9KI/+; Hif-2αfl/fl;Vav-iCre mice and controls and transplanted Lin-Sca-1+c-Kit+(LSK) cells from these mice into primary recipients, and Lin-Sca-1-c-Kit+(LK) cells into secondary recipients.
Results
Hif-2α-deficient and control cells displayed similar re-plating capacity and generated comparable numbers of colonies, but had increased proliferative capacity. Thus, Hif-2α is not required for in vitro transformation and generation of pre-LSCs but suppresses their proliferation. Transplantation of pre-LSCs to primary recipients demonstrated that a smaller proportion of recipients of Hif-2α-deficient pre-LSCs remained leukaemia-free, and therefore succumbed to AML faster than recipients of control pre-LSCs. However, secondary recipients of both Hif-2α-deficient and control LSCs generated aggressive AML with similar latency. In concordance with these data, recipients of Mll-AF9KI/+; Hif-2αfl/fl;Vav-iCre succumbed to AML faster compared to recipients of control LSK cells, whereas, secondary recipients of both genotypes generated AML with similar latency.
Summary
Deletion of Hif-2α in pre-LSCs accelerates development of LSCs and shortens AML latency induced by Mll-AF9 and its downstream effectors Meis1 and Hoxa9. Surprisingly, established LSCs lacking Hif-2α efficiently propagate aggressive AML. We conclude that while Hif-2α suppresses the development of AML, it is not required for LSC maintenance. Therefore, HIF-2 is unlikely to be a broad therapeutic target in AML and the benefit of HIF inhibition should be carefully re-examined in all subsets of AML.
Session topic: Molecular pathogenesis of AML
Abstract: S120
Type: Oral Presentation + travel grant
Presentation during EHA20: From 12.06.2015 12:30 to 12.06.2015 12:45
Location: Room C2
Background
Normal and malignant haematopoiesis occur under hypoxic conditions. Hif-1α and Hif-2α regulate gene expression to facilitate adaptation to low oxygen tension. Several studies investigated the role of Hif-1α and Hif-2α in acute myeloid leukaemia (AML). These studies used shRNA knockdown in human AML samples to show that HIF-1α and HIF-2α knockdown compromised the ability of AML samples to reconstitute AML upon transplantation into recipient mice, suggesting that HIF-1 and HIF-2 are potential therapeutic targets for AML. However, a recent study demonstrated that conditional genetic deletion of Hif-1α did not compromise the development and maintenance of mouse leukaemic stem cells (LSCs) and on the contrary, accelerated the development of AML, indicating that Hif-1α is a tumour suppressor in AML. To date, the effect of conditional deletion of Hif-2α has not been examined in AML.
Aims
To investigate the requirement of Hif-2α in the development and maintenance of AML leukaemic stem cells.
Methods
We generated Hif-2αfl/fl;Vav-iCre mice that lack Hif-2α specifically within the hematopoietic system. We retrovirally co-transduced BM c-Kit+ cells with oncogenes Meis1a and Hoxa9 and serially re-plated them to establish pre-leukaemic stem cells (pre-LSCs). Retrovirally transduced cells were subjected to in vitro assays in normoxia and hypoxia or transplanted into lethally irradiated primary recipients, and subsequently into secondary recipients. We next generated Mll-AF9KI/+; Hif-2αfl/fl;Vav-iCre mice and controls and transplanted Lin-Sca-1+c-Kit+(LSK) cells from these mice into primary recipients, and Lin-Sca-1-c-Kit+(LK) cells into secondary recipients.
Results
Hif-2α-deficient and control cells displayed similar re-plating capacity and generated comparable numbers of colonies, but had increased proliferative capacity. Thus, Hif-2α is not required for in vitro transformation and generation of pre-LSCs but suppresses their proliferation. Transplantation of pre-LSCs to primary recipients demonstrated that a smaller proportion of recipients of Hif-2α-deficient pre-LSCs remained leukaemia-free, and therefore succumbed to AML faster than recipients of control pre-LSCs. However, secondary recipients of both Hif-2α-deficient and control LSCs generated aggressive AML with similar latency. In concordance with these data, recipients of Mll-AF9KI/+; Hif-2αfl/fl;Vav-iCre succumbed to AML faster compared to recipients of control LSK cells, whereas, secondary recipients of both genotypes generated AML with similar latency.
Summary
Deletion of Hif-2α in pre-LSCs accelerates development of LSCs and shortens AML latency induced by Mll-AF9 and its downstream effectors Meis1 and Hoxa9. Surprisingly, established LSCs lacking Hif-2α efficiently propagate aggressive AML. We conclude that while Hif-2α suppresses the development of AML, it is not required for LSC maintenance. Therefore, HIF-2 is unlikely to be a broad therapeutic target in AML and the benefit of HIF inhibition should be carefully re-examined in all subsets of AML.
Session topic: Molecular pathogenesis of AML
Type: Oral Presentation + travel grant
Presentation during EHA20: From 12.06.2015 12:30 to 12.06.2015 12:45
Location: Room C2
Background
Normal and malignant haematopoiesis occur under hypoxic conditions. Hif-1α and Hif-2α regulate gene expression to facilitate adaptation to low oxygen tension. Several studies investigated the role of Hif-1α and Hif-2α in acute myeloid leukaemia (AML). These studies used shRNA knockdown in human AML samples to show that HIF-1α and HIF-2α knockdown compromised the ability of AML samples to reconstitute AML upon transplantation into recipient mice, suggesting that HIF-1 and HIF-2 are potential therapeutic targets for AML. However, a recent study demonstrated that conditional genetic deletion of Hif-1α did not compromise the development and maintenance of mouse leukaemic stem cells (LSCs) and on the contrary, accelerated the development of AML, indicating that Hif-1α is a tumour suppressor in AML. To date, the effect of conditional deletion of Hif-2α has not been examined in AML.
Aims
To investigate the requirement of Hif-2α in the development and maintenance of AML leukaemic stem cells.
Methods
We generated Hif-2αfl/fl;Vav-iCre mice that lack Hif-2α specifically within the hematopoietic system. We retrovirally co-transduced BM c-Kit+ cells with oncogenes Meis1a and Hoxa9 and serially re-plated them to establish pre-leukaemic stem cells (pre-LSCs). Retrovirally transduced cells were subjected to in vitro assays in normoxia and hypoxia or transplanted into lethally irradiated primary recipients, and subsequently into secondary recipients. We next generated Mll-AF9KI/+; Hif-2αfl/fl;Vav-iCre mice and controls and transplanted Lin-Sca-1+c-Kit+(LSK) cells from these mice into primary recipients, and Lin-Sca-1-c-Kit+(LK) cells into secondary recipients.
Results
Hif-2α-deficient and control cells displayed similar re-plating capacity and generated comparable numbers of colonies, but had increased proliferative capacity. Thus, Hif-2α is not required for in vitro transformation and generation of pre-LSCs but suppresses their proliferation. Transplantation of pre-LSCs to primary recipients demonstrated that a smaller proportion of recipients of Hif-2α-deficient pre-LSCs remained leukaemia-free, and therefore succumbed to AML faster than recipients of control pre-LSCs. However, secondary recipients of both Hif-2α-deficient and control LSCs generated aggressive AML with similar latency. In concordance with these data, recipients of Mll-AF9KI/+; Hif-2αfl/fl;Vav-iCre succumbed to AML faster compared to recipients of control LSK cells, whereas, secondary recipients of both genotypes generated AML with similar latency.
Summary
Deletion of Hif-2α in pre-LSCs accelerates development of LSCs and shortens AML latency induced by Mll-AF9 and its downstream effectors Meis1 and Hoxa9. Surprisingly, established LSCs lacking Hif-2α efficiently propagate aggressive AML. We conclude that while Hif-2α suppresses the development of AML, it is not required for LSC maintenance. Therefore, HIF-2 is unlikely to be a broad therapeutic target in AML and the benefit of HIF inhibition should be carefully re-examined in all subsets of AML.
Session topic: Molecular pathogenesis of AML
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