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IL1RAP POTENTIATES MULTIPLE ONCOGENIC SIGNALING PATHWAYS IN AML
Author(s): ,
Kelly Mitchell
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Laura Barreyro
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Tihomira I. Todorova
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Samuel J. Taylor
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Iléana Antony-Debré
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Swathi-Rao Narayanagari
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Luis A. Carvajal
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Joana Leite
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Zubair Piperdi
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Gopichand Pendurti
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Ioannis Mantzaris
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Elisabeth Paietta
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Amit Verma
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
,
Kira Gritsman
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
Ulrich Steidl
Affiliations:
Albert Einstein College of Medicine–Montefiore Medical Center,Bronx,United States
(Abstract release date: 05/17/18) EHA Library. Mitchell K. 06/16/18; 214602; S814
Kelly Mitchell
Kelly Mitchell
Contributions
Abstract

Abstract: S814

Type: Oral Presentation

Presentation during EHA23: On Saturday, June 16, 2018 from 11:30 - 11:45

Location: Room A4

Background
Our group and others previously identified the surface molecule Interleukin 1 receptor accessory protein (IL1RAP) as one of the most significantly upregulated genes in hematopoietic stem and progenitor cells (HSPC) from AML patients and found that its overexpression is correlated with a poor prognosis. IL1RAP is emerging as a novel target for immunotherapy in AML and other myeloid malignancies, however, the cell-intrinsic functions and mechanism of action of IL1RAP in AML cells are largely unknown.

Aims
To investigate therapeutic targeting and the functional and mechanistic role of IL1RAP in AML.

Methods
We used complementary approaches to target IL1RAP (genetic knockout, RNA-interference, and antibody targeting), and measured the functional effects (cell growth, apoptosis, differentiation) of IL1RAP targeting in vitro in AML cell lines, AML patient samples (including leukemic stem cell-enriched populations), and healthy HSPC, and in vivo in AML xenograft models. We generated retrovirally induced leukemias in the wt vs. Il1rap-/- setting and performed competitive transplants of wt vs. Il1rap-/- normal bone marrow cells. Using western blotting, phospho-flow cytometry, EdU incorporation, co-immunoprecipitation and flow cytometric-based Förster resonance energy transfer (FRET), we assessed the molecular effects of IL1RAP targeting and the cellular role of IL1RAP.

Results
We found that IL1RAP targeting inhibited AML growth and viability and promoted differentiation in a cell-intrinsic manner and in the absence of immune effector cells, but did not have inhibitory effects on healthy HSPC. In vivo, IL1RAP targeting inhibited AML xenografts, and Il1rap knockout decreased leukemic stem cell function in an MLL-AF9 AML mouse model. Meanwhile, Il1rap knockout did not perturb healthy stem cell function in competitive transplantation experiments. In exploring the cell-intrinsic molecular bases for these effects, we unexpectedly found that IL1RAP is a promiscuous co-receptor in AML and its function is not restricted to its canonical role in the IL-1 receptor pathway. Specifically, studies by co-immunoprecipitation, FRET, and biochemical assays revealed that IL1RAP physically interacts with and mediates signaling and pro-proliferative effects through FLT3 and c-KIT, two receptor tyrosine kinases with known key roles in AML pathogenesis. Consistent with these mechanistic findings, we found differential sensitivity to IL1RAP targeting of FLT3-mutant and FLT3-wildtype AML cells, a finding with important implications for currently ongoing immunotherapeutic and precision oncology approaches targeting IL1RAP.

Conclusion
Our study reveals novel functional and mechanistic cell-intrinsic roles of IL1RAP in AML, and provides important insight for currently ongoing and future therapeutic strategies targeting IL1RAP.

Session topic: 3. Acute myeloid leukemia - Biology & Translational Research

Keyword(s): Acute Myeloid Leukemia, Leukemic Stem Cell, Signaling, Targeted therapy

Abstract: S814

Type: Oral Presentation

Presentation during EHA23: On Saturday, June 16, 2018 from 11:30 - 11:45

Location: Room A4

Background
Our group and others previously identified the surface molecule Interleukin 1 receptor accessory protein (IL1RAP) as one of the most significantly upregulated genes in hematopoietic stem and progenitor cells (HSPC) from AML patients and found that its overexpression is correlated with a poor prognosis. IL1RAP is emerging as a novel target for immunotherapy in AML and other myeloid malignancies, however, the cell-intrinsic functions and mechanism of action of IL1RAP in AML cells are largely unknown.

Aims
To investigate therapeutic targeting and the functional and mechanistic role of IL1RAP in AML.

Methods
We used complementary approaches to target IL1RAP (genetic knockout, RNA-interference, and antibody targeting), and measured the functional effects (cell growth, apoptosis, differentiation) of IL1RAP targeting in vitro in AML cell lines, AML patient samples (including leukemic stem cell-enriched populations), and healthy HSPC, and in vivo in AML xenograft models. We generated retrovirally induced leukemias in the wt vs. Il1rap-/- setting and performed competitive transplants of wt vs. Il1rap-/- normal bone marrow cells. Using western blotting, phospho-flow cytometry, EdU incorporation, co-immunoprecipitation and flow cytometric-based Förster resonance energy transfer (FRET), we assessed the molecular effects of IL1RAP targeting and the cellular role of IL1RAP.

Results
We found that IL1RAP targeting inhibited AML growth and viability and promoted differentiation in a cell-intrinsic manner and in the absence of immune effector cells, but did not have inhibitory effects on healthy HSPC. In vivo, IL1RAP targeting inhibited AML xenografts, and Il1rap knockout decreased leukemic stem cell function in an MLL-AF9 AML mouse model. Meanwhile, Il1rap knockout did not perturb healthy stem cell function in competitive transplantation experiments. In exploring the cell-intrinsic molecular bases for these effects, we unexpectedly found that IL1RAP is a promiscuous co-receptor in AML and its function is not restricted to its canonical role in the IL-1 receptor pathway. Specifically, studies by co-immunoprecipitation, FRET, and biochemical assays revealed that IL1RAP physically interacts with and mediates signaling and pro-proliferative effects through FLT3 and c-KIT, two receptor tyrosine kinases with known key roles in AML pathogenesis. Consistent with these mechanistic findings, we found differential sensitivity to IL1RAP targeting of FLT3-mutant and FLT3-wildtype AML cells, a finding with important implications for currently ongoing immunotherapeutic and precision oncology approaches targeting IL1RAP.

Conclusion
Our study reveals novel functional and mechanistic cell-intrinsic roles of IL1RAP in AML, and provides important insight for currently ongoing and future therapeutic strategies targeting IL1RAP.

Session topic: 3. Acute myeloid leukemia - Biology & Translational Research

Keyword(s): Acute Myeloid Leukemia, Leukemic Stem Cell, Signaling, Targeted therapy

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