DNA methylation-independent loss of RARA gene expression in acute myeloid leukemia.
The retinoic acid receptor (RAR) alpha gene (RARA) encodes 2 major isoforms and mediates positive effects of all-trans retinoic acid (ATRA) on myelomonocytic differentiation. Expression of the ATRA-inducible (RARalpha2) isoform increases with myelomonocytic differentiation and appears to be down-regulated in many acute myeloid leukemia (AML) cell lines. Here, we demonstrate that relative to normal myeloid stem/progenitor cells, RARalpha2 expression is dramatically reduced in primary AML blasts. Expression of the RARalpha1 isoform is also significantly reduced in primary AML cells, but not in AML cell lines. Although the promoters directing expression of RARalpha1 and RARalpha2 are respectively unmethylated and methylated in AML cell lines, these regulatory regions are unmethylated in all the AML patient cell samples analyzed. Moreover, in primary AML cells, histones associated with the RARalpha2 promoter possessed diminished levels of H3 acetylation and lysine 4 methylation. These results underscore the complexities of the mechanisms responsible for deregulation of gene expression in AML and support the notion that diminished RARA expression contributes to leukemogenesis.
Glasow
Annegret
A
Section of Haemato-Oncology, Institute of Cancer Research, Sutton, United Kingdom.
Barrett
Angela
A
Petrie
Kevin
K
Gupta
Rajeev
R
Boix-Chornet
Manuel
M
Zhou
Da-Cheng
DC
Grimwade
David
D
Gallagher
Robert
R
von Lindern
Marieke
M
Waxman
Samuel
S
Enver
Tariq
T
Hildebrandt
Guido
G
Zelent
Arthur
A
D001854:Bone Marrow Cells / Q000187:drug effects / Q000473:pathology; D002454:Cell Differentiation / Q000187:drug effects; D019175:DNA Methylation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics* / Q000473:pathology; D011401:Promoter Regions, Genetic; D018168:Receptors, Retinoic Acid / Q000235:genetics*; D000072482:Retinoic Acid Receptor alpha; D014212:Tretinoin / Q000494:pharmacology
C000607071:RARA protein, human; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D014212:Tretinoin