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 t he regulatory regions of expressed genes may play a role in hematologic mal ignancy, In the current report, the Restriction Landmark Genomic Scanning ( RLGS) method was used to detect aberrant DNA methylation (M) in acute myelo id leukemia (AML), RLGS-M profiles were initially performed using DNA from diagnostic, remission, and relapse samples from a patient with AML, Rp18, o ne of the eight spots found that was absent in the relapse sample, was clon ed. 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 d ue to a distinct DNA methylation pattern of the WIT-I gene. Twenty-seven AM L patients that entered CR after therapy (i.e., chemosensitive) were studie d and only 10 (37%) of the diagnostic bone marrow (BM) samples showed methy lation of WIT-I, However, seven of eight (87.5%) diagnostic BM samples from primary refractory AML (chemosensitive) showed methylation of WIT-I. The i ncidence of WIT-I methylation in primary refractory AML was significantly h igher than that noted in chemosensitive AML (P=0.018), Together, these resu lts indicate that RLGS-M can be used to find novel epigenetic alterations i n human cancer that are undetectable by standard methods, In addition, thes e results underline the potential importance of WIT-I methylation in chemor esistant AML.