Molecular Detection of Minimal Residual Disease in Acute Leukemia by Novel DNA Methylation Biomarkers.
Jamie Wang, Dali Zheng, Michael Wang. University of Missouri School of Medicine, Columbia
Background: Acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) are the most common hematopoietic malignancies in children and adults, respectively. After initial induction of chemotherapy, a significant number of patients with clinical remission still harbor residual leukemic cells. The presence of the minimal residual disease (MRD, less than 5% leukemia cells) is related to relapse, resulting in a worse prognosis. Current methods for MRD detection include PCR for genetic alterations and multiparameter flow cytometry (MFC) for aberrant antigen expression. In this study, we utilized specific epigenetic DNA methylation as a biomarker to detect MRD.
Design: Genomic DNA was extracted from 3 ALL and 2 AML cell lines, 26 ALL and 35 AML patients, and 10 non-tumor patients' bone marrow samples. Multiple sequential bone marrow and blood samples were also obtained from 3 AML and 2 ALL patients. After DNA digested with four methylation sensitive enzymes (MSE) Aci II, Hpa II, HinP1, and BstU I, the selected CpG island regions of PCDHGA12, RIBP9, SLC26A4, HOXD9, HOXA6 genes and a non-CpG region of the β-actin gene (as internal control) were amplified by a SYBR Green-based real-time PCR. Sss I methylase-treated normal human blood cell DNA was used as a positive control.
Results: Aberrant DNA methylation was detected in both ALL and AML cell lines and patients' samples, but not in non-tumor bone marrow samples (0/10). However, the pattern of DNA methylation in ALL and AML is quite different. All 5 genes (PCDHGA12, RIBP9, SLC26A4, HOXD9, HOXA6) were consistently methylated in 1/3 of ALL patients, only 1 gene (PCDHGA12) was methylated in 1/3 of AML patients. Using PCDHGA12 methylation as a biomarker, MRD was detectible in both ALL and AML patients.
Conclusions: DNA methylation patterns in ALL and AML are unique. PCDHGA12 methylation can be used as a biomarker to detect MRD. This new epigenetic approach may be used as a complimentary clinical test for MRD detection and patient follow-up in addition to classical genetic and immunophenotypic assays.
Tuesday, March 1, 2011 1:00 PM
Poster Session IV # 174, Tuesday Afternoon