TY - JOUR
T1 - ABL1 methylation is a distinct molecular event associated with clonal evolution of chronic myeloid leukemia
AU - Asimakopoulos, Fotis A.
AU - Shteper, Pesach J.
AU - Krichevsky, Svetlana
AU - Fibach, Eitan
AU - Polliack, Aaron
AU - Rachmilewitz, Eliezer
AU - Ben-Neriah, Yinon
AU - Ben-Yehuda, Dina
PY - 1999/10/1
Y1 - 1999/10/1
N2 - Methylation of the proximal promoter of the ABL1 oncogene is a common epigenetic alteration associated with clinical progression of chronic myeloid leukemia (CML). In this study we queried whether both the Ph'-associated and normal ABL1 alleles undergo methylation; what may be the proportion of hematopoietic progenitors bearing methylated ABL1 promoters in chronic versus acute phase disease; whether methylation affects the promoter uniformly or in patches with discrete clinical relevance; and, finally, whether methylation of ABL1 reflects a generalized process or is gene-specific. To address these issues, we adapted the techniques of methylation-specific PCR and bisulfite- sequencing to study the regulatory regions of ABL1 and other genes with a role in DNA repair or genotoxic stress response. In cell lines established from CML blast crisis, which only carry a single ABL1 allele nested within the BCR-ABL fusion gene, ABL1 promoters were universally methylated. By contrast, in clinical samples from patients at advanced stages of disease, both methylated and unmethylated promoter alleles were detectable. To distinguish between allele-specific methylation and a mixed cell population pattern, we studied the methylation status of ABL1 in colonies derived from single hematopoietic progenitors. Our results showed that both methylated and unmethylated promoter alleles coexisted in the same colony. Furthermore, ABL 1 methylation was noted in the vast majority of colonies from blast crisis, but not chronic-phase CML. Both cell lines and clinical samples from acute- phase CML showed nearly uniform hypermethylation along the promoter region. Finally, we showed that ABL1 methylation does not reflect a generalized process and may be unique among DNA repair/genotoxic stress response genes. Our data suggest that specific methylation of the Ph'-associated ABL1 allele accompanies clonal evolution in CML.
AB - Methylation of the proximal promoter of the ABL1 oncogene is a common epigenetic alteration associated with clinical progression of chronic myeloid leukemia (CML). In this study we queried whether both the Ph'-associated and normal ABL1 alleles undergo methylation; what may be the proportion of hematopoietic progenitors bearing methylated ABL1 promoters in chronic versus acute phase disease; whether methylation affects the promoter uniformly or in patches with discrete clinical relevance; and, finally, whether methylation of ABL1 reflects a generalized process or is gene-specific. To address these issues, we adapted the techniques of methylation-specific PCR and bisulfite- sequencing to study the regulatory regions of ABL1 and other genes with a role in DNA repair or genotoxic stress response. In cell lines established from CML blast crisis, which only carry a single ABL1 allele nested within the BCR-ABL fusion gene, ABL1 promoters were universally methylated. By contrast, in clinical samples from patients at advanced stages of disease, both methylated and unmethylated promoter alleles were detectable. To distinguish between allele-specific methylation and a mixed cell population pattern, we studied the methylation status of ABL1 in colonies derived from single hematopoietic progenitors. Our results showed that both methylated and unmethylated promoter alleles coexisted in the same colony. Furthermore, ABL 1 methylation was noted in the vast majority of colonies from blast crisis, but not chronic-phase CML. Both cell lines and clinical samples from acute- phase CML showed nearly uniform hypermethylation along the promoter region. Finally, we showed that ABL1 methylation does not reflect a generalized process and may be unique among DNA repair/genotoxic stress response genes. Our data suggest that specific methylation of the Ph'-associated ABL1 allele accompanies clonal evolution in CML.
UR - http://www.scopus.com/inward/record.url?scp=0033214222&partnerID=8YFLogxK
U2 - 10.1182/blood.v94.7.2452.419k23_2452_2460
DO - 10.1182/blood.v94.7.2452.419k23_2452_2460
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C2 - 10498618
AN - SCOPUS:0033214222
SN - 0006-4971
VL - 94
SP - 2452
EP - 2460
JO - Blood
JF - Blood
IS - 7
ER -