Chronic myelogenous leukemia (CML) results from hematopoietic stem cell (HSC) transformation by the BCR- ABL oncogenic tyrosine kinase. Tyrosine kinase inhibitors (TKI) are highly effective in inducing remission and prolonging survival in CML patients, but do not eliminate primitive, quiescent leukemia stem cells (LSC) responsible for leukemia propagation and regeneration. As a result most patients experience rapid leukemia relapse after TKI discontinuation. However, a subset of patients achieving prolonged, deep remission can successfully discontinue TKI treatment without leukemia recurrence. Our research focuses on understanding mechanisms of LSC resistance to TKI, and development of strategies to target LSC and their microenvironment to prevent leukemia recurrence and enhance treatment free remission (TFR). We now understand that patients achieving TFR continue to harbor small numbers of BCR-ABL+ LSC, suggesting that microenvironmental or immune factor may regulate LSC potential to regenerate leukemia. The bone marrow (BM) microenvironment, which includes diverse hematopoietic and non-hematopoietic cells, plays a critical role in HSC regulation. In contrast, microenvironmental regulation of LSC growth is not well understood. Here we propose to characterize critical niche regulatory mechanisms for maintenance of LSC, and that may contribute to leukemia recurrence after stopping TKI treatment. We have shown that CML development leads to increased levels of several key inflammatory cytokines in the BM, which can provide a selective growth advantage to CML LSC. Our preliminary studies suggest that inflammatory signaling can modify CML BM MSC, resulting in enhanced support for CML LSC, and reduced support of normal HSC.
In Aim 1, we will explore the role of TNFa in mediating alterations in BM MSC, resulting in increased expression of the inflammatory chemokine CXCL1 and enhanced signaling through CXCR2 receptor, in LSC maintenance and leukemia regeneration after TKI treatment. Multipotent mesenchymal stromal cells (MSC), identified on the basis of expression of LepR, nestin or Prx1, represent specialized BM niches that maintain normal HSC. Our preliminary studies show that CXCL12 deletion from Prx1+MSC leads to loss of LSC quiescence and enhanced sensitivity to TKI treatment.
In Aim 2, we will investigate mechanisms of regulation of LSC cycling and treatment resistance by CXCL12-expressing BM MSC niches, focusing on regulation of EZH2 activity in LSC. We will also study the interaction between CXCL12 and inflammatory signaling in modifying MSC niche function. These studies will be conducted using murine models and primary human CML cells. Better understanding of mechanisms underlying microenvironmental regulation of malignant stem cells will help guide development of novel strategies to enhance TFR in CML patients. We further expect that the results of the proposed research will have broader implication towards other leukemias and solid tumors.

Public Health Relevance

Current leukemia treatments are effective in achieving remission, but fail to eliminate small populations of leukemia stem cells that are sustained by the bone marrow microenvironment, and ultimately cause relapse. The proposed research is aimed at achieving improved understanding of the interactions between leukemia stem cells and bone marrow microenvironment cells to develop new treatments that can better target leukemia stem cells, and increase possibilities of cure of leukemia.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA172447-07
Application #
9951003
Study Section
Tumor Microenvironment Study Section (TME)
Program Officer
Klauzinska, Malgorzata
Project Start
2013-07-01
Project End
2024-05-31
Budget Start
2020-06-01
Budget End
2021-05-31
Support Year
7
Fiscal Year
2020
Total Cost
Indirect Cost
Name
University of Alabama Birmingham
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
063690705
City
Birmingham
State
AL
Country
United States
Zip Code
35294
Zhang, Bin; Nguyen, Le Xuan Truong; Li, Ling et al. (2018) Bone marrow niche trafficking of miR-126 controls the self-renewal of leukemia stem cells in chronic myelogenous leukemia. Nat Med 24:450-462
Bhatia, Ravi (2017) Novel approaches to therapy in CML. Hematology Am Soc Hematol Educ Program 2017:115-120
Mesa, Ruben A; Jamieson, Catriona; Bhatia, Ravi et al. (2017) NCCN Guidelines Insights: Myeloproliferative Neoplasms, Version 2.2018. J Natl Compr Canc Netw 15:1193-1207
Agarwal, Puneet; Zhang, Bin; Ho, Yinwei et al. (2017) Enhanced targeting of CML stem and progenitor cells by inhibition of porcupine acyltransferase in combination with TKI. Blood 129:1008-1020
Zhang, Bin; Chu, Su; Agarwal, Puneet et al. (2016) Inhibition of interleukin-1 signaling enhances elimination of tyrosine kinase inhibitor-treated CML stem cells. Blood 128:2671-2682
Irvine, David A; Zhang, Bin; Kinstrie, Ross et al. (2016) Deregulated hedgehog pathway signaling is inhibited by the smoothened antagonist LDE225 (Sonidegib) in chronic phase chronic myeloid leukaemia. Sci Rep 6:25476
Zhang, Bin; Li, Ling; Ho, Yinwei et al. (2016) Heterogeneity of leukemia-initiating capacity of chronic myelogenous leukemia stem cells. J Clin Invest 126:975-91
Bowers, Marisa; Zhang, Bin; Ho, Yinwei et al. (2015) Osteoblast ablation reduces normal long-term hematopoietic stem cell self-renewal but accelerates leukemia development. Blood 125:2678-88
Ă…gerstam, Helena; Karlsson, Christine; Hansen, Nils et al. (2015) Antibodies targeting human IL1RAP (IL1R3) show therapeutic effects in xenograft models of acute myeloid leukemia. Proc Natl Acad Sci U S A 112:10786-91
Agarwal, Puneet; Bhatia, Ravi (2015) Influence of Bone Marrow Microenvironment on Leukemic Stem Cells: Breaking Up an Intimate Relationship. Adv Cancer Res 127:227-52

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