T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive leukemia of immature T-cell progenitors that has a peak incidence in older children and young adults. Although the use of intensified chemotherapy regimens has improved outcomes, T-ALL remains fatal in 20% of children and 50-70% of adults. Our recent work, together with that of Dario Campana's group at St. Jude, has demonstrated that differentiation arrest at the earliest stages of T-cell development predicts a very high risk of treatment failure n T-ALL. These cases are associated with a gene expression signature implicating upregulation of the PI3K-AKT pathway, whereas PTEN deletions also predict treatment failure. Thus, T-ALL treatment failure is associated with AKT pathway activation and with MYC overexpression, a feature common to most cases of T-ALL. We have now shown that MYC and AKT pathway activation both repress mitochondrial apoptosis in a conditional zebrafish model of T-ALL Thus, our central hypothesis is that an apoptotic blockade downstream of MYC and AKT mediates treatment resistance in high-risk T-ALL. However, the mechanisms through which MYC and AKT activation repress mitochondrial apoptosis remain undefined.
In Aim 1, we will exploit the zebrafish model system to test the degree to which repression of BIM underlies apoptosis resistance in high-risk T-ALL with MYC and AKT activation.
In Aim 2, we will combine biochemical analyses with therapeutic studies in high-risk human T-ALLs grown in immunodeficient mice to identify and overcome mechanisms of apoptosis resistance in high-risk human T-ALL. The successful completion of the work proposed here is expected to lead to the identification of mechanisms of resistance to chemotherapy-induced apoptosis in T-ALL cells, as well as to development of therapeutic strategies to overcome these. Given that most patients with high-risk T-ALL cannot be cured with current treatment regimens, the development of novel effective therapies for high-risk T-ALL is expected to represent a major therapeutic advance for these patients.

Public Health Relevance

Despite improvements, current therapy for T-cell acute lymphoblastic leukemia (T-ALL) continues to fail in 20% of children and more than 50% of adults, and these patients have a poor prognosis. High-risk human T-ALL is associated with activation of the AKT and MYC pathways, and we have shown that these pathways block cell death in zebrafish T-ALL cells, implicating these pathways in resistance to chemotherapy-induced cell death. Here, we propose to combine studies in human and zebrafish T-ALL to identify the mechanism underlying this blockade of cell death, and to test therapeutic strategies to overcome this blockade and induce cell death in high-risk T-ALL cells.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21CA167124-01
Application #
8288545
Study Section
Special Emphasis Panel (ZRG1-OBT-A (55))
Program Officer
Wali, Anil
Project Start
2012-06-01
Project End
2014-05-31
Budget Start
2012-06-01
Budget End
2013-05-31
Support Year
1
Fiscal Year
2012
Total Cost
$189,225
Indirect Cost
$80,475
Name
Children's Hospital Boston
Department
Type
DUNS #
076593722
City
Boston
State
MA
Country
United States
Zip Code
02115
Ariƫs, Ingrid M; Bodaar, Kimberly; Karim, Salmaan A et al. (2018) PRC2 loss induces chemoresistance by repressing apoptosis in T cell acute lymphoblastic leukemia. J Exp Med 215:3094-3114
Mansour, Marc R; He, Shuning; Li, Zhaodong et al. (2018) JDP2: An oncogenic bZIP transcription factor in T cell acute lymphoblastic leukemia. J Exp Med 215:1929-1945
Gutierrez, Alejandro; Feng, Hui; Stevenson, Kristen et al. (2014) Loss of function tp53 mutations do not accelerate the onset of myc-induced T-cell acute lymphoblastic leukaemia in the zebrafish. Br J Haematol 166:84-90
Mansour, Marc R; Abraham, Brian J; Anders, Lars et al. (2014) Oncogene regulation. An oncogenic super-enhancer formed through somatic mutation of a noncoding intergenic element. Science 346:1373-7
Chonghaile, Triona Ni; Roderick, Justine E; Glenfield, Cian et al. (2014) Maturation stage of T-cell acute lymphoblastic leukemia determines BCL-2 versus BCL-XL dependence and sensitivity to ABT-199. Cancer Discov 4:1074-87
Reynolds, C; Roderick, J E; LaBelle, J L et al. (2014) Repression of BIM mediates survival signaling by MYC and AKT in high-risk T-cell acute lymphoblastic leukemia. Leukemia 28:1819-27
Zuurbier, Linda; Gutierrez, Alejandro; Mullighan, Charles G et al. (2014) Immature MEF2C-dysregulated T-cell leukemia patients have an early T-cell precursor acute lymphoblastic leukemia gene signature and typically have non-rearranged T-cell receptors. Haematologica 99:94-102