WT1 RNA Expression in Different Cell Lineages in Normal and Leukemic Bone Marrow
Daphne C Ang, Fei Yang, Chenxue Qu, Ginny Lanier, Guang Fan, Richard Press. Oregon Health and Science University, Portland, OR
Background: The WT1 gene is over-expressed in the bone marrow and peripheral blood of patients with acute myeloid leukemia (AML) and high expression levels are prognostic of poor outcomes. WT1 has been previously shown to be expressed in normal CD34+ bone marrow cells, but at a level about 100 to 1000 times lower than in leukemic cells. However, WT1 expression in other cell lineages including PMN's, lymphocytes, and monocytes (in normal and leukemic samples) is unknown.
Design: Bone marrows (BM) from 8 normal, 13 AML (including 1 acute promyelocytic leukemia (APL)), 4 acute lymphoblastic leukemia (ALL) patients; and peripheral blood (PB) samples from 9 AML (including 3 AMML and 3 M5) patients were fluorescence-activated cell sorting (FACS)-sorted into 4 lineages: CD34+ blasts, CD14+/CD64+ monocytes (MONO), CD45+ lymphocytes (LYMPH), and neutrophils (PMN) sorted by characteristic side and forward scatter. FACS-sorted samples were examined for WT1 expression levels by quantitative reverse trascriptase-polymerase chain reaction (normalized to the ABL reference gene).
Results: The WT1 expression level of normal and ALL patients was significantly lower (2-3 logs lower) across all cell lineages as compared to AML patients (p=.02). Among AML samples, WT1 was highly expressed, not only in the blast population but also in the PMNs and to a lesser degree in the monocytes.
|NORMAL||AML (BM)||AML (PB)||ALL|