Mutations in the E-domain of RAR portion of the PML/RAR chimeric gene may confer clinical resistance to all-trans retinoic acid in acute promyelocytic leukemia.
The binding of all-trans retinoic acid (ATRA) to the ligand-binding region in the E-domain of retinoic acid receptor-alpha modifies the transcriptional activity of RARalpha protein. ATRA probably induces differentiation of acute promyelocytic leukemia (APL) cells by binding to the E-domain of the RARalpha portion (RARalpha /E-domain) of PML/RARalpha chimeric protein. Therefore, molecular alteration in the RARalpha /E-domain of the chimeric gene is one mechanism by which patients with APL may acquire resistance to ATRA therapy. In this study using reverse transcription-polymerase chain reaction and single-strand conformation polymorphism, DNA segments amplified from the RARalpha /E-domain in fresh APL cells of 23 APL patients (8 males and 15 females from 4 to 76 years of age) were screened for mutations. Of those patients, 3 patients (1 with de novo and 2 with relapse) had clinical resistance to ATRA therapy. We found mutations in the RARalpha /E-domain of PML/RARalpha chimeric gene exclusively in the 2 patients who exhibited ATRA-resistance at relapse, whereas the mutations were not detected at their initial onset. Interestingly, these patients received a prolonged or intermittent administration of ATRA before relapse with ATRA-resistance. The mutations lead to the change of amino acid in the ligand-binding region of RARalpha /E-domain, Arg272Gln, or Met297Leu according to the amino acid sequence of RARalpha, respectively. Further study demonstrated that the in vitro ligand-dependent transcriptional activity of the mutant PML/RARalpha protein was significantly decreased as compared with that of wild-type PML/RARalpha. These findings suggest that mutations in the RARalpha /E-domain of the PML/RARalpha chimeric gene may confer clinical resistance to ATRA therapy in patients with APL.
Imaizumi
M
M
Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan. mimaizuma@ped.med.tohoku.ac.jp
Suzuki
H
H
Yoshinari
M
M
Sato
A
A
Saito
T
T
Sugawara
A
A
Tsuchiya
S
S
Hatae
Y
Y
Fujimoto
T
T
Kakizuka
A
A
Konno
T
T
Iinuma
K
K
D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics*; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D018168:Receptors, Retinoic Acid / Q000235:genetics; D000072482:Retinoic Acid Receptor alpha; D014212:Tretinoin / Q000494:pharmacology* / Q000627:therapeutic use
D000970:Antineoplastic Agents; D009363:Neoplasm Proteins; D015514:Oncogene Proteins, Fusion; C000607071:RARA protein, human; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; C093476:promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein; D014212:Tretinoin