Session: 617. Acute Myeloid Leukemia: Biology, Cytogenetics, and Molecular Markers in Diagnosis and Prognosis: Poster I
Hematology Disease Topics & Pathways:
Biological Processes, DNA damage, Clinically relevant
Method: One hundred twenty mice were randomized into four groups: PBS+sham IR (control), LDA+sham IR, PBS+IR and LDA+IR. Prior to sham or 3 Gy of IR, CBA/Ca mice were injected with either PBS or LDA intraperitoneally at the dose of 0.4mg/kg for 3 days. At 7, 30 and 180 days after radiation, bone marrow cells were collected from femurs and fixed with Carnoy's Fixative. To assess the effect of LDA on PU.1 gene deletion, fluorescence in-situ hybridization (FISH) assay was performed. An ATTO550 labeled PU.1 probe was designed and used to detect deletions that occur in 2qE1 and involve the PU.1 gene locus, as well as two 6-FAM labeled probes for centromere and telomere respectively. Four to five hundred cells were analyzed for each mouse. Statistical significance was determined from a two-way analysis of variance in log units using SAS Version 9.4.
Result: We successfully established the FISH assay that can specifically detect the PU.1 gene not only in metaphase cells but also in interphase cells. As shown in the figure, mice in the LDA+IR group have significantly fewer bone marrow cells exhibiting PU.1 gene deletion compared with PBS+IR group at all three time points examined (Day 7: 2±1.2% vs 3.7±2.6%, P=0.047; Day 30: 1.9±1.1% vs 3.2±1.9%, P=0.040; Day 180: 2.8±1.0% vs 5.6±3.5%, P=0.014). LDA treatment alone has a negligible effect on PU.1 loss as compared to the control group.
Conclusion: Our result suggests that LDA pretreatment protects genomic integrity following IR treatment in-vivo. As the development of rAML is a multi-step process, the impact of LDA pretreatment on the actual incidence of secondary malignancy needs further validation in animal models. The genome-protective effect of LDA that we have revealed supports its potential use as a strategy to reduce the development of radiation-induced secondary malignances such as MDS and AML.
Disclosures: Ha: Protectum Oncology: Current Employment, Current equity holder in private company.
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