Restriction landmark genome scanning for aberrant methylation in primary refractory and relapsed acute myeloid leukemia;: involvement of the WIT-1 gene

There is substantial evidence to suggest that aberrant DNA methylation in the regulatory regions of expressed genes may play a role in hematologic malignancy, In the current report, the Restriction Landmark Genomic Scanning (RLGS) method was used to detect aberrant DNA methylation (M) in acute myeloid leukemia (AML), RLGS-M profiles were initially performed using DNA from diagnostic, remission, and relapse samples from a patient with AML, Rp18, one of the eight spots found that was absent in the relapse sample, was cloned. Sequence analysis showed that the spot represented a portion of the WIT-1 gene on human chromosome 11p13, Rp18 was missing in the relapse sample due to a distinct DNA methylation pattern of the WIT-I gene. Twenty-seven AML patients that entered CR after therapy (i.e., chemosensitive) were studied and only 10 (37%) of the diagnostic bone marrow (BM) samples showed methylation of WIT-I, However, seven of eight (87.5%) diagnostic BM samples from primary refractory AML (chemosensitive) showed methylation of WIT-I. The incidence of WIT-I methylation in primary refractory AML was significantly higher than that noted in chemosensitive AML (P=0.018), Together, these results indicate that RLGS-M can be used to find novel epigenetic alterations in human cancer that are undetectable by standard methods, In addition, these results underline the potential importance of WIT-I methylation in chemoresistant AML.