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Novel mutation in the PML/RARα chimeric gene exhibits dramatically decreased ligand-binding activity and confers acquired resistance to retinoic acid in acute promyelocytic leukemia
All- trans retinoic acid (RA) resistance in acute promyelocytic leukemia (APL) has been a serious clinical problem in differentiation-inducing therapy. However, the mechanisms underlying acquired RA resistance in APL patients are not well understood. We recently established a spontaneous RA-resistan...
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Published in: | Experimental hematology 2001-07, Vol.29 (7), p.864-872 |
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Main Authors: | , , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | All-
trans retinoic acid (RA) resistance in acute promyelocytic leukemia (APL) has been a serious clinical problem in differentiation-inducing therapy. However, the mechanisms underlying acquired RA resistance in APL patients are not well understood.
We recently established a spontaneous RA-resistant APL cell line (UF-1) from a patient and used this cell line as an excellent in vitro model for RA-resistant clinical situations. We investigated the structural and functional abnormalities of chimeric PML/RARα gene in UF-1 cells and preserved materials from the original patient.
A novel point mutation was detected in the ligand-binding (E) domain of the RARα portion of the PML/RARα gene in UF-1 cells. This mutation resulted in amino acid substitution of Arg611 (
C
GG) for Trp611 (
T
GG) in the short-form PML/RARα protein, which corresponded to Arg276 in wild-type RARα. Importantly, the same mutation was also detected in the preserved materials from the original patient. COS-1 cells were transiently transfected with cDNA encoding wild-type and mutant PML/RARα constructed by site-directed mutagenesis and performed RA-binding assay. Interestingly, RA-binding activity was dramatically decreased in the mutant PML/RARα compared with that of the wild-type chimeric protein, suggesting that this single amino acid substitution is critical for RA binding.
These results strongly suggest that a novel point mutation in the ligand-binding domain of the RARα portion (Arg611) of the chimeric PML/RARα gene decreased sensitivity to all-
trans RA. We conclude that acquisition of the PML/RARα mutation is one possible mechanism for development of RA resistance in patients with APL in vivo. |
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ISSN: | 0301-472X 1873-2399 |
DOI: | 10.1016/S0301-472X(01)00651-8 |