PML-RARalpha and AML1-ETO translocations are rarely associated with methylation of the RARbeta2 promoter.
The acute promyelocytic leukemia-specific PML-RARalpha fusion protein is a dominant-negative transcriptional repressor of retinoic acid receptor (RAR) target genes, which recruits HDAC and corepressor proteins and inhibits coactivators. Another oncogenic transcription factor, AML1-ETO, was proposed to cause an HDAC-dependent repression of RAR target genes. The RAR target RARbeta2 gene has been reported to be frequently silenced by hypermethylation in many types of cancer cells. We examined the methylation status of the RARbeta2 and asked if demethylation could reverse ATRA resistance in ATRA-resistant PML-RARalpha and AML1-ETO-positive cells. PML-RARalpha positive NB4 and its ATRA-resistant subvariant MR2 and AML1-ETO expressing Kasumi-1 cells had heterozygous methylation of RARbeta2. Although DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine partially reversed RARbeta2 CpG methylation in these cells, it did not significantly enhance ATRA-induced RARbeta2 mRNA expression and induction of maturation. However, the histone acetylase inhibitor SAHA combined with ATRA significantly reactivated RARbeta2 mRNA both in NB4 and MR2 cells with degradation of PML-RARalpha, which was associated with maturation. In contrast, SAHA did not affect AML1-ETO levels and failed to induce RARbeta2 expression and maturation in Kasumi-1 cells. In primary AML samples, RARbeta2 expression was uniformly low; however, no specific correlation was observed between the methylation of the RARbeta2 gene and expression of the fusion proteins, PML-RARalpha, and AML1-ETO. These results demonstrate that oncogenic PML-RARalpha and AML1-ETO translocations are rarely associated with RARbeta2 promoter methylation in primary AML samples.
Tabe
Yoko
Y
Section of Molecular Hematology and Therapy, Department of Blood and Marrow Transplantation, The University of Texas M D Anderson Cancer Center, 1400 Holcombe Boulevard, Unit 448, Houston, TX 77030, USA.
Konopleva
Marina
M
Kondo
Yutaka
Y
Contractor
Rooha
R
Jin
Linhua
L
Ruvolo
Vivian
V
Tsutsumi-Ishii
Yuko
Y
Miyake
Kazunori
K
Miyake
Noriko
N
Ohsaka
Akimichi
A
Nagaoka
Isao
I
Issa
Jean-Pierre J
JP
Andreeff
Michael
M
D000970:Antineoplastic Agents / Q000494:pharmacology; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D050676:Core Binding Factor Alpha 2 Subunit / Q000096:biosynthesis* / Q000235:genetics; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D018922:HL-60 Cells; D006655:Histone Deacetylases / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D020014:K562 Cells; D015473:Leukemia, Promyelocytic, Acute / Q000235:genetics / Q000378:metabolism*; D015514:Oncogene Proteins, Fusion / Q000096:biosynthesis* / Q000235:genetics; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D000075142:RUNX1 Translocation Partner 1 Protein; D018168:Receptors, Retinoic Acid / Q000096:biosynthesis* / Q000235:genetics; D014178:Translocation, Genetic / Q000187:drug effects / Q000235:genetics; D014212:Tretinoin / Q000494:pharmacology; D020298:U937 Cells
C107844:AML1-ETO fusion protein, human; D000970:Antineoplastic Agents; D050676:Core Binding Factor Alpha 2 Subunit; D015514:Oncogene Proteins, Fusion; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D000075142:RUNX1 Translocation Partner 1 Protein; D018168:Receptors, Retinoic Acid; C093476:promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein; C082925:retinoic acid receptor beta; D014212:Tretinoin; D000077209:Decitabine; D004248:DNA (Cytosine-5-)-Methyltransferases; D006655:Histone Deacetylases; D001374:Azacitidine