The frequency of therapy-related acute myeloid leukemia (t-AML) continues to increase as the cure ratesfor a wide-variety of cancers improves. Unfortunately, t-AML is a highly aggressive disease and is rarelycurable, with median overall survival rates using current therapies of less than 10%. Detailed cytogeneticand molecular studies of t-AML, in part supported by this program project grant, have provided importantinsights into the underlying molecular pathogenesis of this disease including the loss of the long arm ortotal loss of chromosomes 5 [-5/del(5q)] and/or 7 [-7/del(7q)] in the majority of patients, and the frequentmutation of AML1/RUNX1, FLT3, MLL, NRAS, cKIT, and p53. However, the full complement ofcooperating lesions responsible for the development of t-AML remains to be defined. It is our belief thatdefining at a molecular level the total complement of alterations that contribute to the development of t-AML will not only enhance our ability to accurately diagnosis this disease, but should also help to definethe molecular 'Achilles heels' against which targeted therapy can be developed. The long-term goal ofthis project is to identify the complement of genetic alterations that occur in t-AML. This objective will bepursued through two specific aims: (1) To identify somatically acquired genetic copy number alterations t-AML and to elucidate their mechanistic contribution to cellular transformation; and (2) To identifysomatically acquired sequence mutations in a selected subset of cancer related genes. The latter willinclude known cancer genes and genes identified as either having copy number alterations or alteredexpression profiles.
These specific aims will be pursued using a combination of high resolution genomewidecopy number analysis and targeted resequencing on a cohort of over 200 t-AML samples obtainedthrough the Patient Access, Data Management, Statistical Analysis, and Tissue Culture Core (Core A).Copy number analysis will be performed using Affymetrix Genome-Wide human SNP Array 6.0, whichprovides a resolution of <5 kb. Importantly, matched germ line samples are either available or will begenerated by expansion of BM stromal fibroblasts or reactive T-cells for every patient, allowing us todefinitively determine if an identified copy number change is somatically acquired. Gene mutations thatare identified as the targets of recurrent copy number alterations will be confirmed using FISH or genomicquantitative PCR, and will be sequenced to identify the presence of any point mutations. The identifiedgenes will then be directly assessed for their contribution to cellular transformation by evaluating theireffect on normal hematopoietic stem cell growth and differentiation, and on their ability to cooperate withknown oncogenic lesions to induce leukemia.
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