Selective variegated methylation of the p15/INK4B CpG island is a high frequency event in acute myeloid leukemia (AML)
AuthorDodge, Jonathan Eldon
AdvisorFutscher, Bernard W.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractWe attempted to define target genes that were inactivated in acute myeloid leukemia (AML) by DNA methylation. We hypothesized that hypermethylation of 51 CpG islands is associated with transcriptional silencing of the corresponding gene and participates in either the emergence of drug resistance or the conversion of normal cells to cancer cells. To test this hypothesis the DNA methylation status of the 5' CpG islands of dCK containing 49 CpGs, p15 containing 80 CpGs, and p16 containing 53 CpGs was determined by sodium bisulfite sequencing of normal human peripheral blood lymphocytes (PBL) and bone marrow (NBM), human leukemia cell lines, and cytosine-arabinoside (ara-C)-resistant adult acute myeloid leukemia (AML) patients. In PBL and NBM dCK, p15, and p16 were all unmethylated. dCK was unmethylated in the paired ara-C-sensitive (/S) ara-C-resistant (/R) leukemia cell lines HL60/S & /R and K562/S & /R, and in the 8 AML patients analyzed. p16 was unmethylated in KG-l and KG-1a and both had detectable p16 mRNA and protein. None of the 8 AML patients had aberrant methylation of p16. For p15, a variegated pattern of aberrant methylation was found in KG-1, and complete methylation of p15 was found in KG-1a. The variegated pattern of p15 methylation seen in KG-1 and the complete methylation seen in KG-1a were both associated with no detectable p15 mRNA or protein. p15 was aberrantly methylated in 6 of the 8 AML patients, 5 had a variegated pattern of methylation, and 1 showed complete methylation. We next introduced ectopic p15 and p16 into the p15 and p16 negative human T-cell lymphocytic leukemia cell line Jurkat. The p15 positive clones grew at a slower rate than the parent cell or p16 positive clones as measured by growth in liquid culture and MTS assay. cDNA microarray expression analysis differentiated p15 and p16 positive subclones from the parent cell line but not from each other. This suggests that despite the selective methylation of p15 but not p16 in AML, p15 and p16 are functionally similar.
Degree ProgramGraduate College
Pharmacology and Toxicology