Although considerable progress has been made in understanding the genetic causes of acute myeloid leukemia (AML), the mainstay of chemotherapy, cytarabine in combination with anthracyclines, have been in use for more than 40 years. Despite their clinical utility, the drugs suffer from considerable toxicity and the long-term results are disappointing: the five-year survival rate for AML patients is less than 20%. The focus of this work is on developing better therapy for the approximately 50% of acute myeloid leukemia (AML) cases that over express the homeobox transcription factor HOXA9, along with the HOX cofactor MEIS1. HOXA9/MEIS1 deregulation has been shown to be pivotal for leukemogenesis as well as an important independent marker for adverse prognosis. Our goal is to better define mechanisms of HOX deregulation in leukemia in order to identify critical interactions or enzymatic activities that could be targeted therapeutically. AML cases with deregulation of these targets are strongly associated with rearrangement of the mixed lineage leukemia gene MLL, a histone H3 lysine 4 specific methyltransferase (involved in approximately 10% of all AML cases), mutation of nucleophosmin (NPM1), resulting in its re-localization to the cytoplasm (NPMc+)(approximately 35% of AML cases) or overexpression of CDX2, which occurs in as many as 90% of normal karyotype AML cases. The most common MLL rearrangements are balanced translocations that fuse MLL to one of a number of nuclear translocation factors. In other cases, MLL is fused to translocation partners that dimerize the truncated MLL molecule. Finally, partial tandem duplication of MLL (MLL-PTD), as a result of duplication of sequences encoding the amino terminal MLL, also deregulate HOX gene expression. AML cases with NPMc+ almost never have MLL rearrangements, but share similar expression profiles as MLL rearranged cases as well as strong cooperativity with FLT3 mutations suggesting these cases share final common pathways for HOX deregulation. We discovered that MLL is recruited to HOX loci through interaction with the polymerase associated factor complex, PAFc, where it regulates HOX gene expression through its histone H3 lysine 4 methyltransferase activity. In addition, we and others have found that common MLL fusion proteins recruit the histone H3 lysine 79 methyltransferase DOT1L to target loci and that this recruitment, along with wild type MLL, are all required for transformation. The experiments in this proposal will lay the groundwork for therapeutic targeting of the MLL-PAF axis or DOT1L in leukemias with varying mechanisms of transformation.)

Public Health Relevance

Therapy for acute myeloid leukemia (AML) is associated with considerable toxicity and the long-term results are disappointing: the five-year survival rate for AML patients is less than 20%. This work focuses on developing better therapy for AML by specifically targeting mechanisms that regulate genes required for the survival of AML cells. The experiments outline will identify what AML subtypes are likely to respond to these novel therapies and which therapeutic targets hold the greatest promise for further therapeutic development.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
7R01CA151425-05
Application #
9057741
Study Section
Cancer Molecular Pathobiology Study Section (CAMP)
Program Officer
Mufson, R Allan
Project Start
2015-04-22
Project End
2016-07-31
Budget Start
2015-06-26
Budget End
2015-07-31
Support Year
5
Fiscal Year
2014
Total Cost
$163,784
Indirect Cost
$58,457
Name
Indiana University-Purdue University at Indianapolis
Department
Pathology
Type
Schools of Medicine
DUNS #
603007902
City
Indianapolis
State
IN
Country
United States
Zip Code
46202
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Collins, Cailin T; Hess, Jay L (2016) Deregulation of the HOXA9/MEIS1 axis in acute leukemia. Curr Opin Hematol 23:354-61
Zhou, Bo; Wang, Jingya; Lee, Shirley Y et al. (2016) PRDM16 Suppresses MLL1r Leukemia via Intrinsic Histone Methyltransferase Activity. Mol Cell :
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Collins, Cailin; Wang, Jingya; Miao, Hongzhi et al. (2014) C/EBP? is an essential collaborator in Hoxa9/Meis1-mediated leukemogenesis. Proc Natl Acad Sci U S A 111:9899-904
Shen, Chenxi; Jo, Stephanie Y; Liao, Chenzhong et al. (2013) Targeting recruitment of disruptor of telomeric silencing 1-like (DOT1L): characterizing the interactions between DOT1L and mixed lineage leukemia (MLL) fusion proteins. J Biol Chem 288:30585-96

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